电容式触摸感应面板PCB Layout指南

电容按键PCB layout规则一、 布局1、芯片的位置在PCB 板空间允许的情况下，应尽量将触摸芯片放置在触摸板的中间，使IC的每个感应通道的引脚到感应盘的距离差异最小。

2、稳压电路的放置稳压电路和滤波电路放在触摸板上，在VDD与VSS间并接退耦电容104，靠近IC 放置。

3、通道匹配电阻的放置Sensor通道增加300Ω-2K匹配电阻Rs，Rs靠近IC管脚放置。

4、Cs和Rmod靠近IC放置。

5、复位电路靠近IC放置。

6、按键感应盘（电容传感器）形状、大小和间隙根据手指触摸的习惯，按键盘一般选择圆形和方形。

以圆形为例，按键盘的大小建议在5mm-15mm之间。

按键间隙保持在3mm以上，滑条和滚轮可以缩小到0.5mm。

二、 走线1、遵循数模混合电路设计原则芯片内部集成了精密电容测量的模拟电路，因此进行PCB 设计时应该把它看成一个独立的模拟电路对待。

遵循通常的数模混合电路设计的基本原则。

2、双面板走线如果直接使用PCB板上的铜箔作触摸感应盘，应使用双面PCB板。

触摸芯片和感应盘到IC引脚的连线放在底层（BOTTOM），感应盘放在顶层（TOP）。

3、单面板走线如果采用单面PCB板，并用弹簧或其它导电物体做感应盘，感应盘到IC引脚的连线不走或少走跳线。

4、sensor走线感应盘到IC 的连线应尽量细，双面板采用8-15mil 的线宽，单面板板线宽15-20mil，sensor走线避开大电流和高频信号线，感应盘到触摸芯片的连线周围0.5mm不要走其他信号线。

各sensor走线间距保持在20mil以上，以免交互干扰。

sensor走线长度尽量短，最长不超过30cm。

5、电源走线触摸芯片最好用一根独立的走线从板子的供电点取电，不要和其他的电路（如LED回路）共用电源回路。

触摸IC的供电从滤波电路输入，保持VDD与VSS并行，输入路径短而粗（40mil左右）。

6、采用星形接地触摸芯片的地线不要和其他电路共用，应该单独连到板子电源输入的接地点，也就是通常说的采用“星形接地”。

电容式触摸按键布线分享1）:电容式触摸按键特点及应用与传统的机械按键相比，电容式触摸感应按键不仅美观时尚而且寿命长，功耗小，成本低，体积小，持久耐用。

它颠覆了传统意义上的机械按键控制，只要轻轻触碰，他就可以实现对按键的开关控制，量化调节甚至方向控制，现在电容式触摸感应按键已经广泛用于手机，DVD,电视，洗衣机等一系列消费类电子产品中！2）:电容式触摸按工作基本原理所谓感应式触摸按键，并不是要多大的力量去按，相反，力量大和小的效果是一样的，因为外层一般是一块硬邦邦的塑料壳。

具体就电容式而言，是利用人手接触改变电容大小来实现的，通俗点，你手触摸到哪个位置，那里的电容就会发生变化，检测电路就会检测到，并将由于电容改变而带来的模拟信号的改变转化为数字信号的变化，进行处理！3）: 电容式触摸按电容构成及判断PCB材料构成基本电容，PCB上大面积的焊盘（触摸按键）与附近的地构成的分布电容，由于人体电容的存在，当手指按上按键后，改变了分布电容的容量(原来的电容并上了人体电容)，通过对PAD构成的分布电容充放电或构成振荡电路，再检测充放电的时间，或者振荡频率，脉冲宽度等方式可以检测电容容量的变化，继而可判断按键是否被按下。

电容式触摸按键布板要求1）: PCB板的电容构成因素：PCB板中电容构成因素如右图：其中代表PCB板最终生成电容代表空气中的介质常数代表两板电介质常数代表两极板面面积代表两板距离2）: PCB板的布局电容式感应触摸按键实际只是PCB上的一小块覆铜焊盘，当没有手指触摸时，焊盘和低型号产生约5—10PF的电容值，我们称之为“基准电容”故为了PCB设计尽量达到这值，PCB需要进行更好设计！如下图：虽然触摸按键最终的效果可能与其他一些因素还有很多直接或间接的关系，但做为PCB的绘制人员，我们因该尽量保证我们所绘制的PCB效果达到最佳（及控制好触摸按键的中的基准电容值）PCB布板至关重要，因为PCB构成的电容容量极小,而且必须要尽量控制等效电容，不能过大，因为人体电容也是极小的（数pF），不同的人之间差异也比较大，而触摸按键的灵敏度就在于手指接触按键前后PAD电容量的差异，而且这么小的电容充放电极易受到干扰，所以布线的关键两点就是：1、控制电容量2、避免干扰影响电容容量的因素是极板的面积和极板间的介质材料，在实际应用中人体是不太可能直接接触PCB的，所以PCB与按键接触面必须有覆盖层，在触摸按键应中影响容量的因素有：1、 PAD的面积与铺地间的距离以及铺地的面积2、 PAD上的覆盖层的厚度和材质（介质）3、 PCB的厚度和材质对应的策略如下：1、 PAD的面积应尽量接近手指接触按键的有效面积。

AN2869Application note Guidelines for designing touch sensing applications 1 IntroductionThis application note describes the layout and physical design guidelines used for touchsensing applications.Capacitive sensing interfaces are used in many applications, simple or more complex.These interfaces consist of sensing elements made from conductive elements, such ascopper, connected to the touch sensing controller device.The physical design of the printed circuit board is important and must comply with certaingeneral guidelines that are applicable to all types of applications.This document provides simple guidelines concerning three main layout aspects:1.printed circuit board (PCB),2. overlay materials,3. all another elements not related to PCB or touch sensing such as the chassis or LEDs.February 2009 Rev 11/16Contents AN2869Contents1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12PCB general guideline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.1Board area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2Ground plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3Driven shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.4Communication line isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.5Use of LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.6Voltage regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Electrode and element design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.1Surface capacitance buttons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.1.1Shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.1.2Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.1.3Button-button spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.1.4Button-ground clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.2Sliders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.2.1Slider size and layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103.2.2Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.2.3Diplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.3Wheel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.4Capacitive sensing traces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.4.1Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.4.2Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.4.3Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.4.4Placement by group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4Overlay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 6Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2/16AN2869PCB general guideline 3/162 PCB general guidelineWhen designing printed circuit boards (PCB) for a capacitive sensing application, it isimportant to take into account more than just the circuit that is involved directly with thesensing. The entire circuit affects the capacitance of the sensor elements and their traces.Most often, PCB elements have a negative effect on sensitivity. Hardware elements such ascapacitors, connectors, resistors, LEDs, etc. add parasitic capacitance to the connectedtouch sensing buttons. Traces, even those not involved with sensing, can couple withsensing elements and further decrease application performance.These reasons and many others explain why the entire board layout must be carefullyexamined and optimized when designing capacitive sensing applications.2.1 Board areaFor capacitive sensing, only the area covered by the sensing elements and by the trace areimportant. It is good practice to keep this area small by reducing the distance between thecontroller device and the sensors to a minimum. Centering the device among the sensorelements is one way to ensure an optimized board area.2.2 Ground planeIt is not recommended to run sensor tracks over any power plane.Ground or power floods below sensor tracks increase parasitic capacitance to the groundand reduce sensitivity.When a ground plane is placed under a sensor, the plane must use a criss-cross patternwith less than 40% copper (Figure 1) and placed on the furthest layer to help reduceparasitic capacitance to ground while maintaining a good shielding effect. See alsoSection 3.1.4: Button-ground clearance on page 9.In noisy environments, the most sensitive area may require a ground plane.PCB general guideline AN28694/16Keep any floating metal away from the sensor signals (Figure2) to prevent sensing field re-radiation and to reduce unwanted effects.2.3 DrivenshieldThe principle of a driven shield is to drive the shield with the same signal as the electrode.There are several advantages to using a driven shield instead of a grounded shield:●The parasitic capacitance between the electrode and the shield no longer needs to becharged. This cancels the effect on the sensibility.●The implementation is useful:–“LOAD” signal can be used by the RC software library for driving the shield– A dedicated pin can also be used to drive the shield, as seen in STM8T products●Driven shield is useful for certain applications where shielding may be required to:–Protect the touch electrodes from the noise source–Remove the touch sensibility from a cable or track which are placed between the electrode and the sensing device–Increase performance when a moving metal part is close to the sensing deviceAN2869PCB general guideline 5/162.4 Communication line isolationDo not run capacitive sensing traces close to high-frequency communication lines, such asan I²C or SPI master. The frequency in communication lines can impact the performance ofthe capacitive sensors.If it is necessary to cross communication lines with sensor pins, ensure the intersection isorthogonal, as shown in Figure 6 and Figure 5. Figure 5.Same-layer processing of sensing and communication linesControllerComControllerComCorrectIncorrectPCB general guideline AN28696/16An effective method for reducing the interaction between communication and sensor traces is to select pins mapped on the same side of the package for the touch sensing controller. Figure7 shows a device with a 32-pin QFN package using this type of isolation. Communication and addressing pins are assigned to one side, while sensing is achieved on the other.Figure 7.Port isolation for communication and sensor pins2.5 Use of LEDsLEDs are very often implemented near capacitive sensors buttons on application boards.These diodes are very useful to ensure that the button is correctly touched. When designingapplications boards with LEDs, the following considerations must be taken into account:●LEDs change capacitance when switched on and off●LED driver tracks can change impedance when switched on and off●LED load current can affect the power railIf the LEDs are close to the sensors and very often activated, it is recommended to bypassthe LED or its driver track with a capacitor (less than 1nF).Both sides of the LED must always follow the low impedance path to ground (or power).Otherwise, the LED should be bypassed by a capacitor to suppress the high impedance.The examples of bypass capacitors for the LED using a driver shown in Figure8 can also beapplied to transistors.AN2869PCB general guideline7/162.6 Voltage regulatorIt is strongly recommended to use a voltage regulator for the power supply of the device.The voltage regulator should be placed as far as possible from the sensor trace and thesensing device.The voltage regulator also acts as a filter against conductive noise coming from the powersupply.3 Electrode and element designThe goal of a good PCB layout is to minimize the effect of (non-sensing) elements that donot contain conductive materials, such as copper, that may affect the sensitivity of buttons,slider and touch pads.When designing the PCB, the following recommendations should be taken into account:●Run tracks to electrodes over short distances (less than 100mm if possible)●Use tracks as thin as allowed by the selected PCB technology●Keep the resistive load as close as possible to the controller●For touchkeys, space adjacent key tracks so that gap is at least twice the track widthSensing elementsThe goal of PCB layout should be to minimize the interactions between elements or, if theycannot be minimized, make them uniform for all capacitive elements.Although the touch sensing controller algorithms, used to acquire touchkey signals, take intoaccount that the capacitance of each array is different, it is a good practice to keep things asbalanced as possible.Traces belonging to the same pin group can be close together as shown in Figure9.The following sections describe the most obvious factors and provide guidelines fordesigning a good board layout.3.1 Surface capacitance buttonsA surface capacitance button consists of a single-ended copper electrode connected to thedevice. It does not have to be highly sensitive as it needs only to determine the presence orabsence of a finger.8/163.1.1 ShapeAll types of shapes can be used for capacitive touch sensing. Figure10 shows examples ofpossible shapes. Different shapes do not affect sensing characteristics, but concern boardesthetics only.3.1.2 SizeAll things being equal, larger buttons are typically better. Two buttons connected to thedevice with identical traces will have different sensitivities if they are different in size.A very small button have low surface area and therefore will have a lower touch capacitance(C T) and possibly a very poor sensitivity.Making buttons larger has not been shown to improve C T.However, increasing the button surface in order to be similar to the item to be sensed (finger,thumb, etc.) will increase the C T observed.For finger sensing, buttons with a diameter of at least 0.4 inches (10 mm) arerecommended. Smaller buttons can work, but performance is diminished.Large buttons are more sensitive, however the upper limit of the button size is set by theeffective area of the conductive object.3.1.3 Button-buttonspacingButtons can be adjacent without any problem but when the pitch is small and buttons arevery close together, there may be unwanted interaction between buttons.3.1.4 Button-groundclearanceWhen possible, the ground plane should be not placed on the same layer of the board as thesensing elements.Placing the ground too close to the sensing elements adds capacitance and affects themeasurements used to detect finger presence.9/163.2 SlidersA slider is a set of contiguous capacitive objects connected to the device placed in a singleline. Sliders are typically linear, running only along a single axis.It can be composed of a set of 5 or 8 elements, depending on the required size andresolution.Sliders use differential capacitance changes between adjacent capacitive elements todetermine the central (center of mass) position of a conductive object with greaterresolution.3.2.1 Slider size and layoutThere are various possible designs for sliders.The size and targeted application tend to dictate the slider layout.To ensure that a conductive object couples to more than one element, each element mustbe small enough so that the finger overlaps its outside edge. However, it must also be largeenough to function (sense) through the application overlay.For medium or large sliders, to create more overlap between slider elements, whichprovides better differential change between elements, a sawtooth pattern can be used.We also could use a set of 8 elements in order to have a better resolution.10/163.2.2 SpacingSpacing slider elements with regard to the surrounding ground plane is the same as forbuttons. A space of 0.020 inches (0.5 mm) between the slider element and the ground planereduces the fringe capacitance between the two enough so that its impact on sensing is low.3.2.3 DiplexingDiplexing elements normally provides a better resolution than with contiguous elements, butit is more sensitive to hand shadows.The advantage of diplexing instead of using contiguous element depends on the sliderapplication. Connecting two slider elements to a single pin increases the number of sliderelements that can be sensed by the device. An example of a diplexed slider is shown inFigure15. five is the minimum practical number of pins to use in a diplexed slider. Table1shows some basic diplexing tables.Figure15 represents also the data collected by the device relative to finger position. Thecapacitance of both elements connected to the pin increases. Though changes incapacitance are detected in more than one place, there is only one location (of the two) atwhich all the adjacent elements have a higher capacitance than the baseline.When a signal is detected on three consecutive channels, it means the finger is in that area.Table mon diplexing tablesSlider Diplexing table5 pins, 11 elements 1 2 3 4 5 1 3 5 2 4 18 pins, 17 elements 1 2 3 4 5 6 7 8 1 4 7 2 5 8 3 6 111/1612/163.3 Wheel Figure 16.Basic wheel example (8 electrodes)Same as for the slider, the wheel is a set of contiguous capacitive objects (placed in a circle)connected to the controller pins. It consists of a set of 5 or 8 elements that can be interlaced,like the slider, or directly connected.3.4 Capacitive sensing tracesTraces between the touch sensing controller and the sensors decrease the sensitivity of thesensors by increasing button capacitance and decreasing the signal. T race lengthdecreases sensitivity because it adds parallel capacitance to the sensing circuit that doesnot interact with the finger position, and therefore does not contribute to the signal. T racelength increases noise because the trace picks up noise from both in-circuit and externalnoise sources.3.4.1 LengthShortening trace lengths from the device to the sensor reduces the risk for other designelements to couple to sensing traces. It is best to design traces between the touch sensingcontroller and the sensors as short as possible.3.4.2 WidthTrace width adds to sensor capacitance by adding copper area to the system. It alsoincreases coupling with elements on other layers by way of the increased copper area. So,whenever possible, traces should be kept small and away from the ground.3.4.3 PlacementPlacement of capacitive sense traces must minimize interaction with other design elements,including other capacitive sense traces, whenever possible.Also, keeping traces on the side opposite of the user PCB decreases the impact of a fingeron the traces, ensuring that all capacitive changes on the sensor pin is from the finger's (orother conducting object's) interaction with the active sensing area, and not from interactionbetween the finger and the trace.3.4.4 Placement by groupEach pin on the touch sensing controller, which belongs to the same device port can bedriven together by the software library and are mapped in the same group by software.The trace of all pins in the same group can be close together with a minimum amount ofspace.12345678AN2869Overlay 13/164 OverlayIt is rare that a design gives the end user access directly to the PCB. Rather, there is usuallya material overlay across the surface of the PCB that protects the user from the circuit andthe circuit from the environment.PropertiesOverlays in touch sensing applications MUST NOT be conductive. Metals and otherconductive materials do not form the dielectric of the capacitor when placed between twoconductive plates, such as the finger and the sensor.The capacitance of a parallel plate capacitor is given in Equation 1.Equation 1The geometry of this simple system is captured in the ratio A /d . A is the area of theconductive plates, d is the distance between the plates, εR is the dielectric constant(permittivity) of the material between the sensors, and ε0 is the permittivity of free space.The geometry of the capacitive sensor is more complex than the parallel plate capacitor.The conductors in the sensor include the finger and PCB copper. In general, the geometryof this capacitive system is captured by the function f(A ,d ). Equation 2 states the relationbetween geometry, the dielectric constant, and the system capacitance.Equation 2Like the parallel plate capacitor, the capacitance of the sensor is directly proportional to εR .Different materialsTable 2 lists the dielectric constants of some common overlay materials. Materials with highdielectrics better propagate electrical fields, as with capacitive sensing applications.Table 2.Dielectric constants of common materialsMaterial εRAir 1.00059Glass 4 to 10Sapphire Glass 9 to 11Mica 4 to 8Nylon 3Plexiglass 3.4Polyethylene 2.2Polystyrene2.56C εR ε0A d---------------=C εR ε0f A d (,)=Overlay AN286914/16For a panel built from a stack of different materials, it is possible to have different sensitivities depending on the material of each layer.For instance, a stack of plastic + glue + PCB will have a better sensitivity than a stack of plastic + air + PCB.Air, with a dielectric of 1.0 is not well suited to capacitive sensing applications.This is why air gaps between sensors and the overlay material are not recommended. Eliminating air gaps is also a good practice from a mechanical point of view. ThicknessOverlay thickness is inversely proportional to sensitivity.Wheels and sliders require a good sensitivity, so the overlay thickness must be small (approx. 1 mm).Buttons can support a more important overlay thickness (up to 5mm).Polyethylene Terephthalate (PET) 3.7FR4 (fiberglass + epoxy) 4.2PMMA (Poly methyl methacrylate) 2.6 to 4T ypical PSA (glue) 2.0 - 3.0 (approx.)Table 2.Dielectric constants of common materials (continued)MaterialεRAN2869Chassis 15/165 ChassisThe chassis of a touch sensing application affects the sensitivity of capacitive sensors byinteracting with the sensors and the traces between the controller and the sensors. A metalchassis can be a ground and will tend to make the application less sensitive.The three most common chassis design elements that impact touch sensing are metalsupport structures, communication wires, and the plating of the overlay material on thesensing PCB.Metal support structures must be kept away from sensing elements and traces wheneverpossible. Where support structures are necessary, non-metal structures are recommended.If metal is required for structure or decoration close to the sensor, it must be grounded.The chassis can be also connected to the driven shield if it is implemented.Communication cables must also be kept away from sensors and traces whenever possible.6 ConclusionThe layout and design of capacitive sensing boards usually present conflicts between allsignals present on the application. This document should be used as a general guideline forresolving all issues.In summary, the layout of a touch sensing application should reduce the ground to aminimum and use short wires kept clean and as far away as possible from other potentialinterference sources.7 Revision historyTable 3.Document revision history DateRevision Changes02-Feb-20091Initial release.AN286916/16Please Read Carefully:Information in this document is provided solely in connection with ST products. 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Computer Aided Design of Electrode Pattern in Capacitive Touch Panel s ¥: ¿T: ·E ¤ ~ ¤(Visual Basic for Application)µyUoiXMpuCuiNqeOWqAuhwqNiHteXq×CuiHYupq×Aqu×AiHuhta×q×CbqXAiHBDpqiHoqu×CApueX×X10.2TqeOCVBA Tq10.2AOPzjiHABniBqeBqCqu×OvTqeOIImAqGOvTqu×DAHhMOq×hqu×CPepper (1983)´Xq×hqu×ALoq×OhBsqCTalmage (1987)´XFtq×ALoqAh OPqHCDunthorn (1991)µoFbYhOPqCoXgmiHDhHq×hqCMAbpPoq×OOAHbFXpPRxAYusqeOyCPDA¡AGibson MTq×OVBA (Visual Basic for Application)µyoMpuAuNqoAKiHBtapXPoq×CouOwqAbWhwqnqXoCAAgXRCboputFAbiHhwqq×~HmXhqHXoCGiHhwqXATiHMwCpqGAiHwqCpqoCbuX12.2Tq×PMq×iCAA(Active Area)°PeA~iHwqnAA(Active Area)°aCquiHPmqCNqqVOVOYuqAPmqpCpuftoCGsX1.3%¡AqXu×TqeOCqu×1.77%¡C 10.21. ¥XFXpPRvCqu×qeODnAqGvTqCFMpuAuNqoAKiHBtapXPoq×CRGNAiHpuftt×q×C2. °puOwqAbWwqqXoCAAgXRCpiHtwqq×AYuFcq×CBpuXq×BiC3. ±qCPqXGiHDnWYmqAiHWWemqOArea)°aCquiHPmqCNqqVOVOYuqAPmqpCpuftCGsXqXu×10.2TqeOCqu×1.77%¡C AutoCADqUpuyA AsqeOyVBA (Visual Basic for Application)µyo12.2Tq×PMNmqAA(Active 1.3%¡ACOMPUTER AIDED DESIGN OF ELECTRODE PATTERN INCAPACITIVE TOUCH PANELStudent: Chung-Wen LaiAdvisor: Shih-Ming YangABSTRACTThis thesis aims at developing an efficient method for designing the electrode pattern in capacitive touch panel. The linearity of the electrical field on the capacitive touch panel is very important to the quality of the touch panel, and the distribution of silver electrodes on the panel is the key to improve the electric field.A parametric design tool is established under the Visual Basic for Application (VBA) program language. The dimensions of the silver electrode are parameterized in this parametric design tool. The electrode pattern can be established by defining these parameters. This tool not only can shorten the time of designing the electrode pattern, but also can adjust the geometry of silver electrodes easily. A 12.2 inch electrode pattern is designed by using this parametric design tool to prove the feasibility of this tool. Seven kinds of element geometry test can be used to adjust the layout of the silverelectrodes for good linearity. Finally, a 10.2 inch electrode pattern is fabricated and validated.iCONTENTSPage ABSTRACT (i)CONTENTS (ii)LIST OF TABLES (iii)LIST OF FIGURES (iv)Chapter 1 Introduction1.1 Motivation (1)1.2 Types of Touch Panels (1)1.3 Literature Review (4)1.4 Outline (7)Chapter 2 Parametric Design Tool of Electrode Pattern in Touch Panel2.1 CAD on Electrode Board (12)2.2 The Idea of Establishing Model (13)2.3 Drawing and Analyzing the 12.2 Inch Electrode Pattern (16)2.4 Conclusion (17)Chapter 3 Design and Analysis of Electrode Pattern on Capacitive Touch Panel3.1 Introduction (28)3.2 The Test of Element Geometry (28)3.3 Design an Electrode Pattern on 10.2 Inch Capacitive Touch Panel (35)3.4 Fabricating the 10.2 Inch Capacitive Touch Panel (39)3.5 Conclusion (40)Chapter 4 Summary and Conclusions References…..…………………………………………………………………….…62 ii LIST OF TABLESTable Page1.1 Comparison of Touch Panel (4)2.1 Element Geometry in Electrode Pattern Design (15)3.1 Single Element Test on Changing the Length (29)3.2 Integral Element Test on Changing the Length (29)3.3 Single Element Test on Changing the Width (31)3.4 Integral Element Test on Changing the Width (31)3.5 Single Element Test on Changin g the Position (32)3.6 Integral Element Test on Changing the Position (32)3.7 Single Element Test on Changing the Geometry (33)3.8 Integral Element Test on Changing the Geometry (33)3.9 Single Element Test on Changing the Distance between Two Elements (34)3.10 Integral Element Test on Changing the Distance between Two Elements (34)3.11 Single Element Test on Cutting the Element in Horizontal Direction (34)3.12 Integral Element Tes t on Cutting the Element in Horizontal Direction (34)3.13 Single Element Test on Cutting the Element in Vertical Direction (35)3.14 Integral Element Test on Cutting the Element in Vertical Direction (35)iiiLIST OF FIGURESFigure Page1.1 Th e structure and the work process of optic type touch panel (8)1.2 The structure and the work process of acoustic wave type touch panel (9)1.3 The structure and the work process of capacitive type touch panel (10)1.4 The structure a nd the work process of resistive type touch panel (11)2.1 The user interface of VBA (19)2.2 The work process of designing the electrode pattern (20)2.3 The first parametric dialogue box of electrode pattern design (21)2.4 The second parametric dialogue box of electrode pattern design (22)2.5 The third parametric dialogue box of electrode pattern design (23)2.6 The fourth parametric dialogue box of electrode pattern design (24)2.7 The analysis result of designed pattern in vertical direction (25)2.8 The analysis result of designed pattern in horizontal direction (25)2.9 The user interface of ANSYS (26)2.10 The geometry of U.S. patent (27)2.11 The analysis result of U.S. patent in horizontal direction (27)3.1 The method of measuring the voltage (42)3.2 (a) The length change (b) The width change (43)3.3 The first equipotential line and the interval between two equipotential lines (44)3.4 (a) The position change (b) The geometry change (c) The interval change (45)3.5 (a) The horizontal cut (b) The vertical cut (46)3.6 The g eometry of middle element (47)3.7 The initial electrode pattern (48)3.8 The horizontal electric field of the initial electrode pattern (49)iv3.9 The position of the ideal equipotential lines (50)3.10 The middle element and edge element adjustment (51)3.11 The element of the third part adjustment (52)3.12 The vertical electric field of the initial electrode pattern (53)3.13 The final electrode pattern (54)3.14 The horizontal electric field of the final electrode pattern (55)3.15 The process of fabricating the touch panel (56)3.16 The eGalax company controller (57)3.17 The 10.2 inch capacitive touch panel (58)3.18 The linearity test on the 10.2 inch capacitive touch panel (59)vChapter 1Introduction1.1 MotivationTouch panels are integrated directly onto the screen and they make products lighter and smaller with added portability and convenience. In addition, they can eliminate unskilled users’ fear of using computers. Application products of touch panel including PDA, mobile telephone, GPS navigate panel, e-book, ATM. The aim of this study is integrating with the design and the analysis on electrode pattern of capacitive touch panel. The linearity of the electric field is very important and the layout of silver electrodes influences the linearity of the touch panel directly. Many researches on improving the linearity of the touch panel are presented. However, spending the time on designing the electrode pattern in any size is a serious defect. Visual Basic for Application (VBA) program language is utilized to develop a parametric design tool. The dimensions of the silver electrode are parameterized and the electrode pattern can be established by defining these parameters. This parametric design tool and the function of changing the coordinates on an object in AutoCAD can be used to revise the electrode pattern when the analysis result is unsatisfied.The parametric dialogue box utilized in this tool can simplify the process of constructing the model. In addition, the test of element geometry can be used to adjust the geometry of the silver electrodes for good linearity. The user not only can have aninitial concept on designing the electrode pattern by these testing results but also can shorten the time of designing the electrode pattern.1.2 Types of Touch PanelsThe touch panel application can be divided from personal digital devices to popular facilities devices; mechanics and size of products used in different fields are not the same. 1And the technological principle of touch panel can be divided into following several kinds:(1) Optic type:The component device of optic type touch panel includes glass substrate; infrared light emitting diode (LED) and infrared ray receiver, an array of LED/receiver pairs are mounted on two opposite sides to create a grid of invisible infrared light. It is to utilize the principle of receiving the light source. Touch panel is covered with light source and receiver and made up matrix there. When a user touches the display resulting in obstructing one or more of the light beam, receivers from each axis will detect the absence of light and transmit signals that identify the X and Y coordinates to the computer as shown in Fig. 1.1. The advantage of the optic type touch panel is good dependability and transmittance. The optic type touch panel is applied on ATM, medical system, etc.(2) Acoustic wave type:Acoustic wave type touch panel is made of transmitting transducers, receiving transducers, reflectors, and a controller. Transmitting transducers are located along the horizontal and the vertical edges of a glass plate and receiving transducers are located at the opposite edges of the glass plate. The acoustic wave technology uses inaudible sound waves traveling over the surface of a glass panel. First, the electrical signal is conveyed from controller to the transmitting transducer, and the electrical signal will be transferred to acoustic wave, furthermore, it passes through the surface of glass plate to an array of reflectors directly. Reflectors on the opposite side gather and direct the waves to the receiving transducer, which reconverts them into an electrical signal. Finally, the signal will be transmitted back to the controller that saves the normal condition information. When a user touches the screen, the finger will absorb some acoustic waves, the wave form will be changed at this moment, and this reduced energy will be detected, then the X or Y coordinate location will be calculated as shown in Fig.1.2. The advantage of the acoustic 2wave type touch panel is good protection and higher dots per inch. It is applied for kiosk, and automatic ticket system.(3) Capacitive type:A glass substrate is plated a conductive layer and then an electrode pattern is made on it, finally, covering with a protective layer on the surface. The principle of capacitive touch panel is giving voltages on four corners of the screen to make a stable electric field, when a user touches the screen, transparent electrode and static electricity with the human body that produces the capacitance change, then according to the inducing current to measure its coordinates as shown in Fig. 1.3. Because it is only printed electrodes and transmitted the signals on one glass, so the transmittance of capacitive touch panel is over 90% better than resistive type touch panel. It is good at preventing the dust and the damage, furthermore it has fast response. It is applied for ATM, outdoor guide system, etc.(4) Resistive type:It consists of a pair of ITO conductive layers, spacer dots, and an electrode layer. ITO glass is used to be a substrate covered with an ITO film above, and spreading spacer dots between the ITO glass and ITO film to prevent contact, afterwards printing the silver electrodes along the edge to provide a voltage. When using, a voltage is alternately applied to the horizontal and the vertical axes. When the upper layer is pressed and contacting with the upper conductive layer, that voltage is sensed and sent to a controller that contains an analog-to-digital converter. The voltage is converted to a digital X or Y to indicate the touch location as shown in Fig. 1.4. It is because that the resistive type touch panel is induced by pressure, so there is no limit about touching medium. Therefore, it is applied in the environment without the limitation of touching medium, for instance, supervisory control apparatus, PDA, and industry control, etc. The comparison 3of touch panels is shown in Table 1.1.Table 1.1 Comparison of Touch Panel. (From Ho, 2003)ResolutionOptical clarityTouch life Infrared Acoustic 1024×1024 About 1200/sq. in80~85% Millions 100% Many millionsAbout 1200/sq. in 100000/sq. in92% Many millions 75~85% Many millionsVery1.3 Literature ReviewThe touch panel appeared in 1974, but it came to maturity until that Siemens Corporation proposed Elographics soft glass sensors in 1977. The technologies of touch panel and products have been applied in our daily life more than ten years. Touchpanels were limited by the cost in early stages, so putting on the public machine platforms, and POS/POI (Point of Sales/Point of Information) is the main application. With the change of communication technology and the trend of lighter, smaller, shorter of information products in recent years, in addition, the computer operation system is transferred to GUI (Graphic User Interface) that prompts the computer system more user-friendly. And it is because that the mouse and the keyboard are too big to carry, so the touch panel becomes the standard equipment of portable products.Many researches showed the method to enhance the accuracy of determining the touching point. The way of improving the capacitive touch panel can be divided into reforming the controller and mending the electrode pattern to enhance the linearity of the electrical field. Many means have been done to enhance the precision of converting the 4current signal into the touching coordinate via improving the method of controlling the capacitive touch panel. Pepper (1981) proposed a general method for accurately determining the location or position of a source or sink of electric current on the surface of a resistance element or impedance layer. Touch panel embodiment determines the position of the user’s finger from currents caused by ambient electrical noise. Krein and Meadows (1988) presented a quasistatic electric field applied to a semiconducting coating on the capacitive touch panel surface. A touch draws current from the surface; this current can be used to compute position. If the computation is performed properly, the computed position is independent of touch current and panel coating resistivity. Jhang (2003) proposed a method of controlling the capacitive touch panel. After inputting the stable alternating voltage, the current obtained is amplified. The current difference before and after touching is converted to get the touching coordinate. The above study improves the controller of capacitive touch panel. However, the adjustment of determining the touch point by the controller is limited as the linearity of the electrical field is bad. So the key of enhancing the precision of determining the touching point is improving the electrode pattern. The different electrode patterns invented are described in the following articles.Pepper (1983) invented the edge terminations to provide linearization of the electric field. The edge terminations are constituted by a series of parallel ranks or rows of connective segments overlaid, inlaid or printed at each edge of the polygonal surface with the innermost row or rank being short straight segments and the length of each segment of the next innermost row, respectively, being longer. The central segment in each row or rank is electrically interconnected with the central segments in the other rows. Jheng (2002) proposed an improved touch panel by changing the layout of theresistance conductive lines. Several resistance conductive lines are set on the surface of the touch 5panel. The resistive lines in the one of the regions are smaller than others. It is because that to let the every region has same voltages. By this way, the touch panel can decide the touch point accurately. The concept of establishing the electrode pattern by a series of parallel ranks or rows of silver lines in above patents is utilized on a parametric design tool developed in this thesis. So a user can decide the number of parallel ranks or rows of silver lines. However, when the aspect ratio of the monitor is changed, the fixed electrode pattern in this patent can not support the touch panel for good linearity. Therefore, the parametric design tool can be used to construct any size electrode pattern. Bloom et al. (1986) presented an improved touch panel and a method that increasing the percentage of useful area of a touch-sensitive panel includes electrode elements in electrical communication with an electrically conductive layer of known spatial impedance characteristics. The touch panel structure incorporates improved electrode structure and electrode to impedance layer interfacing elements which impact a more linear mapping function within an expanded touch-sensitive region of the resistive layer. The touch panel can be utilized in a general touch-mapping system without resort to extensive mapping coordinate correction apparatus of earlier systems. Although the percentage of useful area of a touch panel is increased, the region set the silver lines is too large to a touch panel in the present day. And the linearity of the electrical field produced by the layout of an electrode pattern in this patent can’t achieve the demand at present. The area of setting the silver lines can be controlled in this design tool and the linearity can be adjusted by this tool as analysis result is unsatisfied.Gibson and Talmage (1987) showed a resistor electrode type touch sensor having enhanced area of linear response by reducing the bow in perimeters of the sensor and the method of accomplishing the same. Dunthorn (1991) reported a resistor type of gradient sheet for a touch sensor having reduced ripple and bow of equipotential lines along edges 6and in the corners of the sensor. T-shaped electrodes of a selected effective length and spacing are attached to the resistive surface, the length and spacing selected to substantially eliminate the bow of the equipotential fields. The above two works, although the electrode pattern is invented to improve the linearity, the time of adjusting the size of electrode pattern in any size is too long. The concept of revising the pattern can be obtained by the result of element geometry test in this thesis. So the time of establishing the electrode pattern can be reduced.Frey et al. (2003) showed the interest of using finite element simulations in association with partial discharge measurements to determine and localize the maximum field values. Myatt and Marston (1994) presented a coupled electromagnetic and nonlinear structural analysis of a 4.5 tesla superconducting MHD dipole magnet. From the above technical literature, they take a long time to construct the model in ANSYS. In this thesis, the platform of establishing the model is developed. The model is parameterized to shorten the time of constructing and the analysis process is simplified.1.4 OutlineThe motivation of this thesis is described in chapter 1. Then it is introduced with four kind principles of touch panel and there are many people improve the touch panel and create numerous new technologies are introduced in literature review. In chapter 2, it is explained that how to operate the VBA to develop the parametric design tool and the idea of wiring is also illustrated. Afterwards, the parametric design tool is utilized to draw a 12.2 inch electrode pattern. Then the feasibility of the design process is proved by importing the electrode pattern to ANSYS. In chapter 3, seven element geometry tests are used to let the users realize how to adjust the layout of electrode pattern and the 10.2 inch electrode pattern on capacitive touch panel is drawn and fabricated. Finally, there is a conclusion about whole thesis in chapter 4.7Edge of ActiveDisplay Area Opto-Matrix Frame Inside Bezel Grid of Infrared Light Inside and Outside Edges of Infrared TransparentFigure 1.1 The structure and the work process of optic type touch panel. (From ELO TouchSystem)8Transducers Transducers TransducersReflections on each axis divertThe ultrasonic burst across the touchscreenFigure 1.2 The structure and the work process of acoustic wave type touch panel. (From ELO TouchSystem)9Process andComponentsClearTek 3000 OvercoatFinishedSensor Product Electrode PatternConductive CoatingGlassConductive CoatingMinute amount of voltage applied toall corners of touch screenUniform electric fieldTouch draws current from eachcorner of electric field controllerMeasures the ratio of currents todetermine touch locationFigure 1.3 The structure and the work process of capacitive type touch panel. (From 3M TouchSystem)10ITO conductive layerSpacer dotITO conductive coatingGlass bottom circuit layer Top circuit layer Hard coat on surface A flexible hard-coated polyester filmis overlaid on a rigid glass layerFigure 1.4 The structure and the work process of resistive type touch panel.(From ELO TouchSystem)11Chapter 2A Parametric Design Tool of Electrode Pattern in Touch Panel2.1 CAD on Electrode BoardFrom the principle of the capacitive touch panel, the linearity of electric field is very important. The key of influencing the linearity of electric field is the layout of the electrode pattern. So analyzing the electrical field of the electrode layer is very important. In this thesis, Visual Basic for Application (VBA) program language is utilized that interface is shown in Fig. 2.1 in which AutoCAD is to develop a parametric design tool for designing electrode pattern fast, furthermore collocating with ANSYS is computer aided analysis software to analyze and simulate.As to VBA, it is an object-oriented programming environment and it supplies the function of developing that similar to Visual Basic language. In general, the main discrepancy between VB and VBA is executing in the same procedure space with AutoCAD, providing an intelligent AutoCAD and a speedy program design environment. In addition, VBA also can integrate other application programs, which have VBA ability. It means that AutoCAD can be an automation controller in other application programs, for instance, Microsoft Word or Excel. VBA will transmit the messages through the AutoCAD ActiveX Automation interface to the AutoCAD, and AutoCAD also permits VBA environment and AutoCAD can implement at the sametime. Therefore, the way of combination for AutoCAD, ActiveX Automation, and VBA supplies powerful interface, not only can control internal objects of AutoCAD but can transmit or get information between other application programs. There are four advantages for using VBA: 1. VBA is learned and used easily under the Visual Basic language environment, 2. VBA and AutoCAD are operated in the same procedure, it means that the programs can be executed very fast, 3. dialogue boxes are established fast and effectively, that let developer 12prototypes application programs and gets the response of design fast, and 4. projects can be independent or set in the drawings, this flexible selection supplies developers on sending to other application programs. To the general finite element analysis software, for instance, I-DEAS, PATRAN, NASTRAN, MARC, etc., the way to analyze is importing the entity's model directly and utilizes solution module to analyze, if the users are unsatisfied with the analysis result, and wants to revise the part of model, they must revise entity's model again, imports to the software and analyzes again, makes the process of analysis seems long.VBA is utilized to develop a set of parameter type design tool. The size of the silver lines is parameterized by this tool. So long as a user follows the dialogue box to design the pattern and then can execute analysis fast, shortening the time of construction the model in the analysis. The process of designing the electrode pattern is shown in Fig. 2.2. The electrode pattern is established by using a parametric tool under the AutoCAD design software. Then this electrode pattern model is exported in IGES (Initial Graphics Exchange Specification) file type and it is imported to the computer aided analysis software to read and establish the model. There are two methods for building analysis model in computer aided analysis software; here GUI (Graphic User Interface) is utilized to obtain various electrical field effects of electrode pattern and electrical field uniformity. The above-mentioned using parametric language designs electrode patterns include the width and the length of silver electrode, and geometry of electrode board. After supplying the power to a transparent electrode of touch panel, the electrical field uniformity of whole touch panel should be cared. If the linearity is not good, it will decrease the accuracy that controller determines the position. So analyzing electrical field linearity of whole electrode board is a key to estimate the quality of touch panels.2.2 The Idea of Establishing ModelIt is beginning to introduce the concept of this parametric design tool. 1/4 of the 13 electrode pattern is set up and then the whole panel is established by the way of reflection are initial thought. First, the frame size of the touch panel has to be confirmed. The method is deciding the length and the width of the frame of the touch panel.Afterward, defining the length and the width of AA district (active area) is the next step. The parametric dialogue box is illustrated in Fig. 2.3.The length and the width of the frame and AA district are parameterized. It lets users revise the size of the touch panel easily. And then a region set the silver electrodes is detected between the frame and AA district. This region can be subdivided into several small areas on this design idea. To clarity the description, the silver electrodes printed on ITO substrate are called the picture element and as long as it can be drawn under the AutoCAD software that can be joined and used. There are four kinds of elements supported to choose as shown in Table. 2.1. The picture element chosen will be put in each small area and the elements will be reproduced in 1/4 of the panel by the way of the reflection and then the elements in 1/4 of the panel are set to the whole panel in the same way.The reason of reflecting the elements in this way is simplifying the design complexity. Thus the layout of the electrode pattern is getting symmetrical. This way can improve the linearity of the touch panel after analyzing the electric field and achieve the final purpose of developing this parametric design tool. The four corners of the whole electrode pattern are applied voltages. So they must be designed separately. Because of considering the symmetrical relation, the edge elements on the corner are all the same. The geometry of the edge element is not important to affect the linearity of the electric field. So only the length and width of the edge element is defined. According to Gibson and Talmage (1987), non-uniformity electric field near the perimeter of the AA district is produced by the voltage drop. It means that the equipotential line near the edge would be a curve line. 14So the middle element is also designed separately to improve this defect as shown in Fig.2.4.。

Capacitive Touch SensorDesign GuideOctober 16, 2008Copyright © 2007-2008 Yured International Co., Ltd.1YU-TECH-0002-012-1 (3) (3) (5) (9) (11) (11) (17) (20)Copyright © 2007-2008 Yured International Co., Ltd.2YU-TECH-0002-012-1Copyright © 2007-2008 Yured International Co., Ltd.3YU-TECH-0002-012-11.2.( ) 3M 468MP NITTO 500 818Copyright © 2007-2008 Yured International Co., Ltd.4YU-TECH-0002-012-13.4.Front PanelSensor PadSensor PadElectroplatingOrSpray PaintNothingCopyright © 2007-2008 Yured International Co., Ltd.5YU-TECH-0002-012-11. (FPC) ITO (Membrane)ITO ITO ( 10K )FPC ITO MEMBRANEPCBCopyright © 2007-2008 Yured International Co., Ltd.6YU-TECH-0002-012-12.ITO LCD ITO ( 10K )3. 1mm 8mm ( 8mm X 8mm )1mm 8mm X 8mm 2mm 10mm X 10mm 3mm 12mm X 12mm 4mm 15mm X 15mm 5mm18mm X 18mm( ) 196.85 mil (5mm)0.254mm(10mil)2mm 5mm2mmCopyright © 2007-2008 Yured International Co., Ltd.7YU-TECH-0002-012-14.5. 20mil (0.508mm) IC 20mil (0.508mm) 10mil (0.254mm) 78.74 mil (2mm)Copyright © 2007-2008 Yured International Co., Ltd.8YU-TECH-0002-012-16. IC 30cm20cm IC 7. LED( )Copyright © 2007-2008 Yured International Co., Ltd.9YU-TECH-0002-012-11.LCD ( ) 2mm2.RF 6mm ( )Copyright © 2007-2008 Yured International Co., Ltd.10YU-TECH-0002-012-13.( 10mm) ( )4.1 2mmIC IC IC1. IC2. 10M ±10%±10% (1uF) (22pF) ±20%3. ±500mV(VDD=5V) ±300mV(VDD=3V) ±100mV/1V(VDD)IC 2.5V4. 8MHz RC OSCI (C =22pF)RC OSCI IC ICCopyright © 2007-2008 Yured International Co., Ltd.11YU-TECH-0002-012-1Copyright © 2007-2008 Yured International Co., Ltd.12YU-TECH-0002-012-15.CHIP OP VDD VSS OP+R VDD VSS (R 47K 100K )6. Button (GPIO) 1 (Active-High) 0(Active-Low) Button 1 0 1 0 1 07. Open-Drain GPIO 0 (Vss) 1Wire AND ( )IC Open-Drain8. Toggle Toggle (ON)(OFF) ON 0 1 OFF 0 1 (Mode)OUTn ActiveINPn T TActiveT TCopyright © 2007-2008 Yured International Co., Ltd.13YU-TECH-0002-012-19. Inter-Lock Toggle Push-Pull Active-Low OUT1INP1 OUT2OUT3 OUT4 OUT3 OUT2 OUT410. (INP) 10M (GND) 10M22pF 256uS IC 30cm 20cmKEYINP10MCopyright © 2007-2008 Yured International Co., Ltd.14YU-TECH-0002-012-1Copyright © 2007-2008 Yured International Co., Ltd.15YU-TECH-0002-012-111. IC ( IC ) ICIC SLEEP VDD VSS HOST 0 IC HOST 1 IC IC 256mS 384mS SLEEP 1 ICCopyright © 2007-2008 Yured International Co., Ltd.16YU-TECH-0002-012-112. 6.5 ICTouch INPn OUTnActive Touch Active 13.(INP) 3.2IC 14. IC 16mS 24mS Active-LowPull-High Active-High Pull-Low15. MODE VSS(GND) R=47KC=0.001uF(102) C=0.01uF(103) IC OSCI 250KHz ( 50%)MODERCopyright © 2007-2008 Yured International Co., Ltd.17YU-TECH-0002-012-11.INP 10M OSCI RC Bypass IC IC ( ) 2. OSCI RC3.ITO ITO 10K4.IC ( ) 196.85 mil (5mm)Layer2Layer 1Layer 10.254mm(10mil)2mm 2mm5mm5mm5. 1mm 8mm ( 8mm X8mm)1mm8mm X 8mm2mm10mm X 10mm3mm12mm X 12mm4mm15mm X 15mm5mm18mm X 18mm( ) 196.85 mil (5mm)0.254mm(10mil)5mm 2mm5mm2mm 0.508mm(20mil)2mm5mm0.254mm(10mil)2mmCopyright © 2007-2008 Yured International Co., Ltd.18YU-TECH-0002-012-16. INP 10mil (0.254mm) IC 20mil (0.508mm)20mil (0.508mm) 78.74 mil (2mm) 196.85 mil (5mm) IC 30cm 20cmCopyright © 2007-2008 Yured International Co., Ltd.19YU-TECH-0002-012-1Copyright © 2007-2008 Yured International Co., Ltd.20YU-TECH-0002-012-1OSCI 8MHz VDD ±100mV/1V (VDD)。

介绍本应用指南旨在为，电容触摸感应设计所用的各种PCB(印刷电路板) (如FR4、柔性PCB 或ITO面板)的结构和布局提供设计布局指导。

在目前市场上可提供的PCB基材中，FR4是最常用的一种。

FR4是一种玻璃纤维增强型环氧树脂层压板，PCB可以是单层或多层。

在触摸模块的尺寸受限的情况下，使用单层PCB不是总能行得通的，通常使用两层或者多曾PCB。

我们将以最常用的两层PCB为例来介绍PCB布局指南。

PCB设计与布局在结构为两层的PCB中，触摸控制器和其他部件被布设在PCB的底层，传感器电极被布设在PCB的顶层。

图.1 基于两层板的电容式触摸模组的结构每个传感器通道所需的调谐匹配电容器可以直接布设在该传感器电极的底层。

需要指出的是，触摸控制器布设在底层，应该保证其对应的顶层没有布设有任何传感器电极。

顶层和底层的空白区域可填充网状接地铜箔。

图2.1两层PCB板的顶层图2.2两层PCB板的底层设计规则第1层(顶层)●传感器电极位于PCB的顶层(PCB的上端与覆层板固定在一起)。

为提高灵敏度，建议使用尺寸为10 x 10 毫米的感应电极。

可以使用更小尺寸的感应电极，但会降低灵敏度。

同时，建议感应电极的尺寸不超过15 x 15毫米。

如果感应电极超过这一尺寸，不但会降低灵敏度，而且会增加对噪声的易感性。

●空白区域可填充接地铜箔(迹线宽度为6 密耳，网格尺寸为30密耳)。

●顶层可用来布设普通信号迹线(不包括传感器信号迹线)。

应当尽可能多地把传感器信号迹线布设在底层。

●感应电极与接地铜箔的间距至少应为0.75毫米。

第2层(底层)●控制器和其它无源部件应该设计布局在底层。

●传感器信号迹线将被布设在底层。

不要把一个通道的传感器信号迹线布设在其他传感通道的感应电极的下面。

图.3 触摸极板下的传感器信号迹线走线方式●空白区域可填充接地铜箔(迹线宽度为6 密耳，网格尺寸为30密耳)。

●传感器信号迹线与接地铜箔的间距应当至少是传感器信号迹线宽度的两倍。

層專用）表示鉻版，Oc表示該層為oc層，且膜面向上,TP30327A為產品的型號，V0表示版本號表示該層為metal層，且膜面向下；此標識各層都需要，而且需位於成品功能區以外ITO測詴方塊金屬邊框5.3.15 保護藍膠絲印對位元標記：在ITO Glass切割之前要對圖案進行保護，即玻璃正反面絲印保護藍膠，則需要在ITO Glass的MT層上製作對位元標記以保證保護藍膠與玻璃的絲印位置，對位元標記設計尺寸如下圖所示：5.3.16 形版的命名方法：A〃鉻版：在該產品的型號前面加上圖形鉻版的代號護塗層：塗有明膠塗層以防止損傷感光乳劑層。

裡面可能包含無光澤詴劑。

光乳劑層：均勻地塗有鹵化銀的微小晶體，以明膠作為介質。

塗層：該層用於把感光乳劑層粘到膠片基上。

6.1 ITO Film結構Sensor具體設計ITO Film結構Sensor圖形設計包括AG，ITO和保護藍膠。

另外在圖紙設計時需結合客戶的要求和內部的工藝制程能力。

下面按照Atmel方案進行ITO圖形的設計6.1.1 ITO 設計Atmel方案，ITO圖形設計為條形，據圖如下左圖，ITO橫向為發射極，ITO圖形較寬；縱向為接受極，窄。

具體通道設計區尺寸以4.76mm為PIN距來計算，如上右圖所示。

测试块印刷对位标记印刷方向正膠設計圖紙背膠設計圖紙7.1.2 背膠設計ITO FILM sensor所用背膠為整面印刷，與sensor排版尺寸一致即所有圖案區域，如上圖背膠設計圖紙所示FPC熱壓位置正膠設計單模正膠設計7.2.1.2 電容玻璃正膠的設計電容玻璃為大片玻璃正面向下進行切割，則需要正面保護藍膠的設計滿足切割的工藝要求，在其進行切割時保證刀具周邊的平整，減少切割時崩邊、崩角的不良，降低微裂紋的深度，玻璃周邊需要設計絲印對位元標記，如下圖電容玻璃正膠設計7.2.2 背膠設計7.2.2.1 單模背膠的設計背膠設計要考慮玻璃切割時的公差及絲印公差，要求背膠尺寸比玻璃外形單邊縮小0.8mm,保證切割時不能切到藍7.2.2.2 電容玻璃背膠的設計電容玻璃切割時為背面向上，背膠只需要按照玻璃排膜方式將單模背膠按照陣列方式進行排列即可，如下圖所示：電容玻璃背膠設計圖紙設計8.1 FPC材料介紹22 FPC金手指長度需滿足以下條件：將FPC金手指處的對位標與PANEL ITO引腳處的對位標對齊熱壓後，FPC金手指頂端不能超過ITO 端，一般低於ITO引腳約0.1mm，且金手指下端不超過PAENL,鏤空板的金手指設計，參見下圖上對位標因鋼模偏位而被切掉和銅箔翹起等品質不良,在設計靠邊對位標時(L)(mm) 寬(W)(mm) 高(t)(mm)0.60±0.050.30±0.050.23±0.050.10±0.05確定FPC外形時盡可能考慮元件區域是否合適2.若整機結構允許，FPC遮罩角儘量避免180度彎折來壓合，直接搭接在sensor背面壓合，其設計尺寸與以上方案設計尺寸一致4. 製作LAYOUT圖(1) 導入FPC外形：將第 1 步做出來的 FPC 外形圖 DXF層屬性改為 ALL LAYER,並將線寬改為(2) 製作PCB元件封裝：依據 FPC 模切圖中的各介面尺寸，在2.互電容走線設計：互電容原理，sensor包括TX，RX，通過TX與RX間的耦合電容變化來確定是否有觸摸，對於走線，交叉，交叉越多，在走線上引起電容變化越大，影響效果。

使用使用说明说明说明 V1.0一、Touch TouchP P ad 表面表面贴贴附物附物(Cover)(Cover)(Cover)材质材质材质要求要求要求::目前一般贴附物分三种:a. Plastic Cover(塑料)b. Mylar Cover(亚克力)c. Glass Cover(玻璃)注意：1．最大限制:Sensor 贴附物不可以是金属和含有导电或弱导电物质(如:碳等)的材质; 2. TouchPad 与Cover 之间需紧密的接合，尽量不要有空隙，所以机构设计需考虑组装 方法.建议:将Sensor PCB 以胶直接贴附于Cover 下方，或可加上支撑架加以固定;二、Layout 注意事项注意事项:: 1. TouchPad 面积建议不小于25mm²(能穿透2mm 左右Cove),其感度与贴附物的材质,层数以及IC 的工作电压有关，材质越厚、层数越多,IC 工作电压越低，则感度越低,穿透 相同厚度要求的TouchPad 面积越大；如果Cover 厚度大于3mm,尽量把PAD 做大一点(大 于70 mm²).2. TouchPad 的形状如下均可:3. Touchpad 的下面尽量不要走线，特别是大电流电路和脉冲信号电路；4. Touchpad 的Trace 线宽: 6～10mil,建议尽量小;5. Touchpad 的Trace 之间的间距D: D>10mil(0.254)；6. Touchpad 以及Trace 与地之间的间距D: D>20mil(1.27mm)；7. 避免Touchpad 的Trace 与其它数字电路及大电流电路（LED 驱动电路）并行走线， 以免其相互干扰；8. Touchpad 的Trace 应尽量减少过孔； 9.走线图示如下:10. 铺地要求:正面: Trace:8mil,Gap:20mil(类似比例也可);背面: Trace:8mil,Gap:45mil(类似比例也可);11. TouchPad 的表面可以露铜或盖滤油,建议盖绿油,防止PAD 氧化.错误走线正确正确走线走线图形图形说明说明: 表示PCB 截面表示与PCB 截面垂直的走线表示与PCB 截面平行的走线TP 走线地线其他信号走线。

S-Touch电容式触摸控制器PCB布局指南
黄梓佑;崔景城;焦彤彤
【期刊名称】《电子产品世界》
【年(卷),期】2009(016)008
【摘要】本文旨在为S-TouchTM电容触摸感应设计所采用的各种PCB(印刷电路板)的结构和布局提供设计布局指导,包括触摸键,滑动条和旋转条.鉴于在多种应用中,两层PCB板被广泛采用,本文以两层PCB板为例,介绍PCB板的设计布局.【总页数】5页(P12-16)
【作者】黄梓佑;崔景城;焦彤彤
【作者单位】意法半导体亚太区;意法半导体大中国区;意法半导体大中国区
【正文语种】中文
【相关文献】
1.瘦身计划：减少微控制器使用的电容式触摸屏控制器案例分析 [J], Eric Siegel
2.Silicon Labs全新TouchXpress电容式触摸控制器在贸泽开售 [J],
3.电容式触摸控制器PCB布局 [J], 无
4.全新电容式触摸控制器系列 [J],
5.瑞萨电子超低功耗微控制器对带LED和LCD显示屏的电容式触摸按键应用进行优化 [J],
因版权原因，仅展示原文概要，查看原文内容请购买。

电容式触摸板布线及设计说明1、Sensor Pad形状可根据结构选择圆形、方形或三角形，实心（无须绿油）。

避免使用狭长型焊盘。

2、Sensor Pad大小根据结构选择合适大小，一般需满足成人手指接触面积相当，直径8~15mm为适。

通用型：0.5 inch*0.5 inch 方形3、Sensor Pad间距减小相邻Sensor Pad之间的干扰，其之间的距离不能太小，≧2.5mm4、覆盖层材料选择及注意点（硬件调试时需知）①由于不同材料的介电常数不同，对应的触摸灵敏度及精度都会有所不同，玻璃＞亚克力＞空气，确保Sensor Pad与覆盖层之间没有残留空气②覆盖层中不能含有电感性材料（如金属），其会吸收Sensor Pad产生的电力线，影响到感应灵敏度或直接失效。

【若更改电路参数增强灵敏度，同样会导致抗干扰性降低】5、布局布线①Pad走线：尽可能窄，7~10mil为适，且尽量避开地线及其余走线（特别是通信信号线I2C、SPI等，如若不能，则应垂直布线），减小寄生电容及串扰。

走线长度尽量短，≦35cm，以保证信号稳定。

相邻PAD走线也应尽量避开（满足3W原则）。

如若不能，可再两者之间添加地线隔离（或用最小线宽进行覆铜）。

②振荡RC、PAD附属RC都应靠近触摸IC，且其下方勿走高频走线。

③使用双面板时，尽量使PAD处于top层，其余布线走bottom层，且PAD下方勿走高频走线及其余PAD感应线。

④Top层可覆铜，其PAD与地线之间的距离要大，≧1.59mm。

6、元件材质选择（设计时应注意）振荡RC、PAD附属RC尽量选用温度系数较好的材质，如X7R、NPO等。

销售部2：TEL:130****8198，QQ:2881651176 投诉与建议:134****1600数据手册DATASHEETASC8022K(同步模式直接输出) ASC8022S(保持模式锁存输出) 2键触摸感应开关芯片IC(Rev:1.4)销售部2：TEL:130****8198，QQ:2881651176投诉与建议:134****1600一、产品概述ASC8022K、ASC8022S是为实现人体触摸界面而设计的一款电容式触摸控制ASIC芯片，可替代机械式轻触按键，实现防水防尘、密封隔离、坚固美观的操作界面。

支持2通道触摸输入和输出，具有低功耗、高抗干扰、宽工作电压范围、高穿透力的突出优势。

二、主要特性1、工作电压范围：2.4～5.5V。

2、待机功耗低, 待机电流：9uA@VDD=5V & CMOD=10nF；6.5uA@VDD=3V & CMOD=10nF。

3、按键响应时间：小于100ms。

4、上电0.5秒快速初始化。

环境自适应功能，可快速应对先上电后覆盖介质、触摸上电等应用场景。

5、HBM ESD：±5KV以上。

6、按键持续长按最长时间：16秒(±30%)7、采用电荷分享方式实现触摸，独立2通道触摸按键输入输出。

8、有效电平选择(AHLB)：可引脚配置高电平输出有效或低电平输出有效9、内置高精度LDO稳压源电路单元模块、上电复位(POR)、低压复位(LVR)、硬件去抖。

10、内置实时环境自适应算法，可随环境温度变化、触摸介质的环境变量调整参考值，确保按键判断正常工作。

11、内置高效数字滤波算法措施，抗电源纹波能力强，对电源纹波的干扰有很好的耐受能力，可抵抗＜0.5V的电源纹波。

可靠性高，不影响芯片正常工作，有效防止由外部噪声干扰导致的误动作。

12、抗大功率RF发射设备、对讲机干扰能力强，近距离、多角度干扰情况下触摸响应灵敏度及可靠性不受影响。

13、高灵敏度，用户可自行调节， CMOD脚的外接电容Cm为灵敏度调节电容，电容越大灵敏度越高。

S-TouchTM 电容式触摸控制器PCB布局指南介绍本应用指南旨在为S-TouchTM电容触摸感应设计所用的各种PCB(印刷电路板) (如FR4、柔性PCB 或 ITO面板)的结构和布局提供设计布局指导。

在目前市场上可提供的PCB基材中，FR4是最常用的一种。

FR4是一种玻璃纤维增强型环氧树脂层压板，PCB可以是单层或多层。

在触摸模块的尺寸受限的情况下，使用单层PCB不是总能行得通的，通常使用四层或两层PCB。

我们将以最常用的两层PCB为例来介绍PCB布局指南。

PCB设计与布局在结构为两层的PCB中，S-TouchTM触摸控制器和其他部件被布设在PCB的底层，传感器电极被布设在PCB的顶层。

图.1 基于两层板的电容式触摸模组的结构每个传感器通道所需的调谐匹配电容器可以直接布设在该传感器电极的底层。

需要指出的是，S-TouchTM触摸控制器布设在底层，应该保证其对应的顶层没有布设有任何传感器电极。

顶层和底层的空白区域可填充网状接地铜箔。

图2.1 两层PCB板的顶层图 2.2 两层PCB板的底层设计规则第1层(顶层)● 传感器电极位于PCB的顶层(PCB的上端与覆层板固定在一起)。

为提高灵敏度，建议使用尺寸为10 x 10 毫米的感应电极。

可以使用更小尺寸的感应电极，但会降低灵敏度。

同时，建议感应电极的尺寸不超过 15 x 15毫米。

如果感应电极超过这一尺寸，不但会降低灵敏度，而且会增加对噪声的易感性。

● 空白区域可填充接地铜箔 (迹线宽度为6 密耳，网格尺寸为30密耳)。

● 顶层可用来布设普通信号迹线(不包括传感器信号迹线)。

应当尽可能多地把传感器信号迹线布设在底层。

● 感应电极与接地铜箔的间距至少应为0.75毫米。

第2层(底层)● S-TouchTM控制器和其它无源部件应该设计布局在底层。

● 传感器信号迹线将被布设在底层。

不要把一个通道的传感器信号迹线布设在其他传感通道的感应电极的下面。

图.3 触摸极板下的传感器信号迹线走线方式● 空白区域可填充接地铜箔 (迹线宽度为6 密耳，网格尺寸为30密耳)。

Application NoteTitle: Layout Guidelines of IT7250/ 7260Part No.: IT7250/7260 Chip Ver: BXDoc No.: ITAE-AN-09-1-09 Doc Ver: V1.0Date: June 25, 2010 Confidential Table of Contents1 IT7250/7260 FPC/PCB Layout Guidelines (2)1.1 Reference circuit (2)1.2 Layout guidelines (3)2 IT7250/IT7260 ITO Layout Guidelines (6)2.1 Cap. sensor traces and shield signal layout (6)2.2 IT7250/IT7260 Support Three Types of ITO sensors (8)2.3 ITO with button format (17)1. IT7250/7260 FPC/PCB Layout Guidelines1.1 Reference circuit(1) The reference circuit of IT7250 is shown in Figure1-1 and 1-2. And theIT7260’s components are the same with IT7250.Figure.1-1 IIC interfaceR1, R2, R3, and R4: are optional for host address settingIf host’s I2C bus has pull up resisters, R6 and R7 can be removed on FPCFig. 1-2 SPI Interface(2) The recommended component area of FPC is 9 X 9 mm for IT7250 and12 X 12 mm for IT7260.(3) If the FPC connector still have unused pins, it is recommended to addground pins to reduce grounding impedance.1.2 Layout guidelinesCapacitance sensor trace (CIN trace) width: 4 mils are recommended. The air gap between each CIN trace and signal which is connected to ITO sensor should be bigger than 4 mils if 4-mils width line is used for each trace.The FPC grounding impedance needs smaller than 3 ohm.The way via a hole is not recommended for capacitance sensor traces.If this way is required for PCB/FPC, please drill the hole nearIT7250/7260 and/or ITO connector; and the maximum number of via holes are 2.Analog ground could be a plane or wide trace line and is connected to digital ground plane by a 40-mil width short trace line. It should beseparated from FPC/PCB connector side’s digital ground, as shown in Figure 2.Fig. 2IIC signal trace layout should be separated farther apart from capacitance sensor traces to further decrease unknown noise coupling to ITO. A GND plane under IIC signals is recommended to get good IIC bus performance, as shown in Figure 3.The ITO shield pin should be connected to the IT7250/IT7260 shield pin, and the pin could not be connected to GND. Whole CINs (fromIT7250/7260) connected to ITO layout trace should be surrounded with shield plane to get good performance. The upper layer of the FPC is shield plane while the lower layer of it is capacitance sensor’s golden fingers which connect FPC to ITO in order to enhance the accuracy of the positionestimation, as shown in Figure 3.Fig. 3Thermal pad of IT7250/7260 is connected to GND plane, as shown in Figure 4.Fig. 4To improve the ESD capability, please implement the following design.More FPC space is required to add extra GND pad in order to contact that GND plane of FPC and the GND chassis of system module, as shown in Figure 5.Fig. 52. IT7250/IT7260 ITO Layout Guidelines2.1 Cap. sensor traces and shield signal layout(1) Shield Signal of IT7250/7260:To decrease the noise, it is recommended to add a trace line out of ITO’s Capacitance sensor signal area and connect it to IT7250/7260 Shield signal, as shown in Figure 6.Fig. 7-1 Fig. 7-2 (3)Cap. sensor trace with dummy line on ITO:Adding a dummy line as shown in Figure 8 can decrease noise and avoid the positioning errorFig. 82.2 IT7250/IT7260 support three types of ITO sensors (1) One layer without bridge: Right triangle set formatOne layer without bridge:The number of right triangle set in each bar should be 4(as shown in Figure 9-1) if the bar height is above 7mm. Otherwise, a bar with 3-set right triangle (as shown in Figure 9-2) is enoughFig. 9-1Fig. 9-2Height of bar:10mm of the maximum height is recommended for each bar. For the bar height above 7mm and below 10mm, 4 pairs of right triangle in each bar is recommended (Figure10-1). Otherwise, 3 pairs are for the heightbelow 7mm, as shown in Figure 10-2.Fig. 10-2Right triangle set format:The bar pattern is formatted by two symmetrical right triangle sets, as shown in Figure 11.Fig.11Gap between two bars:The gap between each bar should be as small as possible to increasethe touch sensing area, as shown in Figure 12Fig. 13Gap between two caps sensor traces:The gap shown in Figure 14 between each dummy line and the nearby traces should be as small as possible to enhance the positioningaccuracy of the border area.Fig. 15Gap between shielding signal and bar of board side:The gap shown in Figure 16 between shielding signal and the barshould be as close as possible to enhance the positioning accuracy of the border area.(2) One layer with bridge (SITO): Diamond formatOne-layer ITO:For the one-layer ITO sensor shown in Figure 18-1 and 18-2 with the diamond pattern, it is necessary to add bridges to x-axis or y-axis.Fig. 18-1Fig. 18-2 x-axis or y-axis ITO patternDiamond Size:To enhance the positioning accuracy, it is recommended to have the diamond width and height about 5mm to 6mm, as shown in Figure 19.Fig. 19(3) Two layers without bridge (DITO): Diamond formatTwo-Layer ITO:For the two-layer ITO sensor See Figure 20-1 and 20-2 with the diamond pattern, it is not necessary to add any bridges to x-axis or y-axis.Fig. 20-1Fig. 20-2 two-layer –x-axis or y-axis form.Diamond size:To enhance the positioning accuracy, it is recommended to have the diamond width and height about 5mm to 6mm, as shown in Figure 19.The common issue for two layer ITO layout and ITE’s solution:Since IT7250/60 detects the finger touch by sensing the capacitance difference between channels, sometimes the improper trace layout may cause ghost point. For example, once finger touches on Area-F where traces from A to B are covered (Figure 21). Line X since trace B gotCDC value and the line will be detected abnormally. That usuallyhappens on film sensor.Fig. 21There are some solutions to decrease this ghost point issue.(a) For two-layer sensor, please put Figure 22-1 layout on top layer andFigure 22-2 on bottom layer.Fig. 22-1 Fig.22-2(b) Insert shield signal trace line of IT7250/7260 between X-axis and Y-axis,as shown in Figure 23.Shield Signal of IT7250/7260Fig. 23(c) For FPC side, please put shield or GND plane on top layer andcapacitance sensor traces on bottom layer, then the finger cannot touch on capacitance sensor trace directly.2.3 ITO with button formatPlease check with Figure 24. There has a dummy Capacitance sensor trace line (blue line) be other buttons differential pair to enhance button detection.Fig. 24。

1.电源A.优先采用线性电源，因为开关电源有所产生的纹波对于触摸芯片来说影响比较大B.触摸IC的电源采用开关电源时，尽量控制纹波幅度和噪声。

在做电源变化时，如果纹波不好控制，可采用LDO经行转换C.触摸芯片的电源要与其他的电源分开，可采用星型接法，同时要进行滤波处理。

如果电源干扰的纹波比较大时可以采用如下的方式：2.感应按键A.材料根据应用场合可以选择PCB铜箔、金属片、平顶圆柱弹簧、导电棉、导电油墨、导电橡胶、导电玻璃的ITO层等但在安装时不管使用什么材料，按键感应盘必须紧密贴在面板上，中间不能有空气间隙。

B.形状：原则上可以做成任意形状，中间可留孔或镂空。

我们推荐做成边缘圆滑的形状，如圆形或六角形，可以避免尖端放电效应C.大小最小4mmX4mm,最大30mmX30mm，有的建议不要大于15mmX15mm，太大的话，外界的干扰相应的也会增加D.灵敏度一般的感应按键面积大小和灵敏度成正比。

一般来说，按键感应盘的直径要大于面板厚度的4倍，并且增大电极的尺寸，可以提高信噪比。

各个感应盘的形状、面积应该相同，以保证灵敏度一致。

灵敏度与外接CIN电容的大小成反比；与面板的厚度成反比；与按键感应盘的大小成正比。

CIN电容的选择：CIN电容可在0PF～50PF选择。

电容越小，灵敏度越高，但是抗干扰能力越差。

电容越大，灵敏度越低，但是抗干扰能力越强。

通常，我们推荐5PF～20PFE.按键的间距各个感应盘间的距离要尽可能的大一些（大于5mm），以减少它们形成的电场之间的相互干扰。

当用PCB铜箔做感应盘时，若感应盘间距离较近（5MM～10MM），感应盘周围必须用铺地隔离。

如图：各个按键距离比较远，周围空白的都用地线隔开了。

但注意地线要与按键保持一定的距离面板必须选用绝缘材料，可以是玻璃、聚苯乙烯、聚氯乙烯（pvc）、尼龙、树脂玻璃等。

在生产过程中，要保持面板的材质和厚度不变，面板的表面喷涂必须使用绝缘的油漆。

在电极不变的情况下，面板的厚度和材质决定灵敏度。

第三章LAYOUT 分析3.1 ITO及相关介绍3.1.1 什么是ITOITO 是Indium Tin Oxides的缩写，中文意为：氧化铟锡，是一种N型氧化物半导体。

ITO薄膜即铟锡氧化物半导体透明导电膜，是一种在均匀载体上通过特殊工艺生成的透明导电薄膜，主要的性能指标是电阻率和光透过率。

下面分别介绍一下其最常见的两种应用：3.1.2 ITO GLASSITO GLASS即ITO导电膜玻璃，是通过ITO导电膜玻璃生产线,在无尘的生产环境中,利用平面磁控技术,在超薄玻璃上溅射氧化铟锡导电薄膜镀层并经高温退火处理得到。

根据其特性可以有以下几种分类：①按阻抗分类分为高阻抗玻璃（方阻在150~500奥姆）、普通玻璃（方阻在60~150奥姆）、低玻璃（方阻小于60奥姆）。

高电阻玻璃一般用于静电防护、触控屏幕制作用；普通玻璃一般用于TN类液晶显示器和电子抗干扰；低电阻玻璃一般用于STN液晶显示器和透明线路板。

②按尺寸分类可以分为中大尺寸，中尺寸和小尺寸。

中大尺寸主要包括：10.1英寸，11,6英寸，12.1英寸，13.3英寸，14.1英寸和15.6 英寸；中尺寸主要包括：7英寸，9.7英寸；小尺寸主要包括：2.8英寸，3.2英寸，3.5英寸，3.8英寸，4.0英寸，4.3英寸，5英寸；③按厚度分类分为2.0mm、1.1mm、0.7mm、0.55mm、0.4mm、0.3mm等规格，厚度在0.5mm 以下的主要用于STN液晶显示器产品。

④按平整度分类分为抛光玻璃和普通玻璃。

⑤按强度分类分为普通玻璃和强化玻璃。

3.1.3 ITO FILMITO FILM 是指以均匀的硬化PET膜为载体，通过ITO导电膜玻璃生产线，在无尘的环境中，利用特殊的生产技术加工的得到的。

目前最常用到的PET膜叫做聚对苯二甲酸乙二醇酯，具有较宽的温度适用范围和良好的机械物理性能，可以在120°的高温下长期使用，具有良好的电绝缘性。