Method of manufacturing touch sensors

Roll-to-roll processes for manufacturing touch sensors on a plastic base film are provided. The touch sensors can be deposited on the base film using various patterning techniques. One or more shorting bars can also be patterned onto the base film to couple together traces, such as drive lines, sense lines, conductive traces, and the like, of the touch sensor to prevent a potential difference from forming between traces due to static buildup during the manufacturing process. After the touch sensor is fully formed on the base film, the touch sensor can be removed from the base film using lithography or a physical cutting process. The removal process can separate the touch sensor from the one or more shorting bars, thereby uncoupling the traces of the touch sensor.

FIELD

This relates generally to touch sensors and, more specifically, to roll-to-roll processes for manufacturing touch sensors.

BACKGROUND

Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens, and the like. Touch sensitive devices, such as touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation. A touch sensitive device can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device, such as a liquid crystal display (LCD) or organic light emitting diode (OLED) display, that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. The touch sensitive device can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus, or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, the touch sensitive device can recognize a touch event and the position of the touch event on the touch sensor panel, and the computing system can then interpret the touch event in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch event.

Many processes have been developed to manufacture these touch sensors. For example, conventional roll-to-roll processes involve patterning electronic devices onto rolls of thin, flexible plastic or metal foil. These devices can then be removed from the roll using lithography or a physical cutting process. These roll-to-roll processes can reduce the amount of time and money required to manufacture touch sensors. However, when using roll-to-roll processes to manufacture a touch sensor onto a flexible plastic material, static electricity can build up, causing short periods of high current in the touch sensor circuitry when the static electricity is discharged. This can damage the conductive traces of the touch sensor, resulting in undesirable open circuits. Thus, improved plastic roll-to-roll processes are desired.

SUMMARY

This relates to roll-to-roll processes for manufacturing touch sensors on a plastic base film. The touch sensors can be deposited on the base film using various patterning techniques. One or more shorting bars can also be patterned onto the base film to couple together traces, such as drive lines, sense lines, conductive traces, and the like, of the touch sensor to prevent a potential difference from forming between traces due to static buildup during the manufacturing process. After the touch sensor is fully formed on the base film, the touch sensor can be removed from the base film using lithography or a physical cutting process. The removal process can separate the touch sensor from the one or more shorting bars, thereby uncoupling the traces of the touch sensor.

DETAILED DESCRIPTION

In the following description of the disclosure and examples, reference is made to the accompanying drawings in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be practiced and structural changes can be made without departing from the scope of the disclosure.

This relates to roll-to-roll processes for manufacturing touch sensors on a plastic base film. The touch sensors can be deposited on the base film using various patterning techniques. One or more shorting bars can also be patterned onto the base film to couple together traces, such as drive lines, sense lines, conductive traces, and the like, of the touch sensor to prevent or reduce the amount of potential difference between traces due to static buildup during the manufacturing process. After the touch sensor is fully formed on the base film, the touch sensor can be removed from the base film using lithography or a physical cutting process. The removal process can separate the touch sensor from the one or more shorting bars, thereby uncoupling the traces of the touch sensor.

FIG. 1illustrates touch sensor100that can be used to detect touch events on a touch sensitive device, such as a mobile phone, tablet, touchpad, portable computer, portable media player, or the like. Touch sensor100can include an array of touch regions or nodes105that can be formed at the crossing points between rows of drive lines101(D0-D3) and columns of sense lines103(S0-S4). Each touch region105can have an associated mutual capacitance Csig111formed between the crossing drive lines101and sense lines103when the drive lines are stimulated. The drive lines101can be stimulated by stimulation signals107provided by drive circuitry (not shown) and can include an alternating current (AC) waveform. The sense lines103can transmit touch signals109indicative of a touch at the touch sensor100to sense circuitry (not shown), which can include a sense amplifier for each sense line, or a fewer number of sense amplifiers that can be multiplexed to connect to a larger number of sense lines.

To sense a touch at the touch sensor100, drive lines101can be stimulated by the stimulation signals107to capacitively couple with the crossing sense lines103, thereby forming a capacitive path for coupling charge from the drive lines101to the sense lines103. The crossing sense lines103can output touch signals109, representing the coupled charge or current. When an object, such as a stylus, finger, etc., touches the touch sensor100, the object can cause the capacitance Csig111to reduce by an amount ΔCsig at the touch location. This capacitance change ΔCsig can be caused by charge or current from the stimulated drive line101being shunted through the touching object to ground rather than being coupled to the crossing sense line103at the touch location. The touch signals109representative of the capacitance change ΔCsig can be transmitted by the sense lines103to the sense circuitry for processing. The touch signals109can indicate the touch region where the touch occurred and the amount of touch that occurred at that touch region location.

While the example shown inFIG. 1includes four drive lines101and five sense lines103, it should be appreciated that touch sensor100can include any number of drive lines101and any number of sense lines103to form the desired number and pattern of touch regions105. Additionally, while the drive lines101and sense lines103are shown inFIG. 1in a crossing configuration, it should be appreciated that other configurations are also possible to form the desired touch region pattern. WhileFIG. 1illustrates mutual capacitance touch sensing, other touch sensing technologies may also be used in conjunction with examples of the disclosure, such as self-capacitance touch sensing, resistive touch sensing, projection scan touch sensing, and the like. Furthermore, while various examples describe a sensed touch, it should be appreciated that the touch sensor100can also sense a hovering object and generate hover signals therefrom.

FIG. 2illustrates a top-view of exemplary touch sensor200that can be incorporated within a device, such as a touch sensitive phone, portable media player, tablet computer, or the like. For purposes of explanation, drive lines101and sense lines103(represented by the dashed lines) are shown in the viewable area201of touch sensor200. However, it should be appreciated that drive lines101and sense lines103can be made from transparent, or at least substantially transparent, materials, such as indium tin oxide (ITO), silicon oxide, other transparent oxides, or the like. As such, drive lines101and sense lines103may not be visible to the user.

Touch sensor200can include conductive traces203(represented by the solid lines) for coupling drive lines101and sense lines103to bond pads205. Bond pads205can be used to couple drive lines101and sense lines103to circuitry for driving drive lines101and circuitry for interpreting touch signals from sense lines103. In some examples, conductive traces203may be made from a non-transparent material, such as copper or other metals.

As discussed above, touch sensors, such as touch sensors100and200, and touch sensitive devices can be manufactured using roll-to-roll processes. However, when using these processes with plastic mother sheets or base films, static charge can build up between traces, such as drive lines101, sense lines103, and conductive traces203. If a sufficient amount of charge is generated, short periods of high current can occur in these traces. This can damage the conductive traces of the touch sensor, resulting in undesirable open circuits.

FIG. 3illustrates an exemplary roll-to-roll process300that can be used to manufacture touch sensors, such as touch sensors100and200, and other touch sensitive electronic devices. Process300can include the use of a shorting bar to couple together the traces of the touch sensors or touch sensitive devices during the manufacturing process, thereby preventing or reducing the potential difference between traces due to static buildup. Once the manufacturing process is complete, the shorting bar can be separated from the touch sensors or touch sensitive devices.

At block301of process300, a touch sensor or touch sensitive device can be formed on a base film. To illustrate,FIG. 4shows multiple touch sensors200formed on a sheet of base film401. In some examples, the sheet of base film401can include a flexible plastic material, such as cyclo olefin polymer (COP), and a touch sensor similar or identical to touch sensors100or200can be formed on the sheet of base film401using any known patterning technique, such as deposition or photolithography. As an example,FIGS. 5-12illustrate the formation of touch sensor200on a sheet of COP base film401at various stages of manufacture using an exemplary etching process.

Initially,FIG. 5illustrates an exemplary sheet of COP base film401having a hard-coat (HC) layer, index matching (IM) layer, indium tin oxide (ITO) layer503, and copper layer505. The HC layer and IM layer have been combined into a single HC and IM layer501for simplicity, but it should be appreciated that these layers can be separate layers. To form touch sensor200on the sheet of COP base film401, a layer of dry film resist (DFR)507can be laminated onto the copper layer505of the sheet of COP base film401, as shown inFIG. 6. Portions of the DFR layer507can then be etched away to define the conductive traces, drive lines, and sense lines of touch sensor200, as shown inFIG. 7. For example, portions of DFR layer507can be etched away to define drive lines101, sense lines103, and conductive traces203. Specifically, portions of DFR layer507above drive lines101, sense lines103, and conductive traces203can be left intact while the remaining portions of DFR layer507can be etched away. Using the remaining DFR layer507as a mask, portions of copper layer505and ITO layer503can be etched using an appropriate etchant, as shown inFIG. 8. The remaining DFR layer507can then be etched away, as shown inFIG. 9. A second DFR layer1007can then be deposited on portions of sheet401corresponding to the conductive traces of the device, as shown inFIG. 10. For example, a second DFR layer1007can be deposited onto conductive traces203of touch sensor200. Using the second DFR layer1007as a mask, portions of copper layer505can be etched away, as shown inFIG. 11. In the example where the second DFR layer1007is deposited onto conductive traces203of touch sensor200, the portions of copper layer505within viewable area201can be removed. The second DFR layer1007can then be etched away, leaving the drive lines, sense lines, and conductive traces of touch sensor200, as shown inFIG. 12. For example, using the example provided above, drive lines101formed of ITO, sense lines103formed of ITO, and conductive traces203formed of copper and ITO can be created using this exemplary etching process.

FIGS. 5-12show the patterning of both sides of the sheet of COP base film401. It should be appreciated that different components of the touch sensor can be patterned on each side of the sheet of COP base film401. For example, the drive lines and associated conductive traces can be patterned on the bottom of the sheet of COP base film401, while the sense lines and associated conductive traces can be patterned on the top of the sheet of COP base film401. One of ordinary skill in the art can arrange the components of the touch sensor based on its desired application.

Referring back to process300ofFIG. 3, after forming the touch sensor on the base film at block301, the process can proceed to block303. At block303, one or more bond pads can be formed on the base film. For example, bond pads similar or identical to bond pads205can be formed on a sheet of base film401such that they are coupled to conductive traces203as shown inFIG. 2. In some examples, the bond pads205can extend beyond an edge207of touch sensor200, as shown inFIG. 2. The bond pads can be formed using known patterning techniques, such as deposition or photolithography. In some examples, an etching process similar or identical to that described above with respect toFIGS. 5-12can be used. In yet other examples, the bond pads can be formed at the same time as the formation of the drive lines, sense lines, and conductive traces at block301. For instance, the DFR layer507can be deposited over an area of sheet401corresponding to drive lines101, sense lines103, conductive traces203, and bond pads205to prevent etching of the underlying portions of copper layer505and ITO layer503in these areas. After etching, the first DFR layer507can be removed. The second DFR layer1007can then be deposited over an area of sheet401corresponding conductive traces203and bond pads205to prevent etching of the underlying portions of copper layer505and ITO layer503in these areas, resulting in copper conductive traces203and bond pads205. Alternatively, the second DFR layer1007can be deposited over an area of sheet401corresponding to conductive traces203to prevent etching of the underlying portions of copper layer505and ITO layer503in these areas, resulting in copper conductive traces203and ITO bond pads205. The second DFR layer1007can then be removed.

Referring back to process300ofFIG. 3, after forming the bond pad on the base film at block303, the process can proceed to block305. At block305, one or more shorting bars can be formed on the base film. The shorting bars can include copper or ITO and can couple together contacts of the bond pads formed at block303. For example, bond pads205include contacts209corresponding to each coupled drive line101or sense line103. A shorting bar211can be formed on a sheet of base film401such that they couple together two or more contacts209of bond pads205, as shown inFIG. 2. While shorting bars211are shown coupling together all contacts209within their respective bond pads205, it should be appreciated that other configurations are possible. For example, a single shorting bar211can be used to couple together all contacts209of all bond pads205. In other examples, a first shorting bar211can be used to couple together all contacts209that are coupled to drive lines101and a second shorting bar211can be used to coupled together all contacts209that are coupled to sense lines103. In yet other examples, shorting bars211can couple together less than all contacts209within a single bond pad205.

The shorting bars can be formed using known patterning techniques, such as deposition or photolithography. In some examples, an etching process similar or identical to that described above with respect toFIGS. 5-12can be used. In yet other examples, the shorting bars can be formed at the same time as formation of the drive lines, sense lines, and conductive traces at block301and/or the formation of the bond pads at block303. For instance, the DFR layer507can be deposited over an area of sheet401corresponding to drive lines101, sense lines103, conductive traces203, bond pads205, and shorting bars211to prevent etching of the underlying portions of copper layer505and ITO layer503in these areas. After etching, the first DFR layer507can be removed. The second DFR layer1007can then be deposited over an area of sheet401corresponding conductive traces203, bond pads205, and shorting bars211to prevent etching of the underlying portions of copper layer505and ITO layer503in these areas, resulting in copper conductive traces203, bond pads205, and shorting bars211. Alternatively, the second DFR layer1007can be deposited over an area of sheet401corresponding to conductive traces203and bond pad205to prevent etching of the underlying portions of copper layer505and ITO layer503in these areas, resulting in copper conductive traces203, copper bond pads205, and ITO shorting bars211. The second DFR layer1007can then be removed.

Referring back to process300ofFIG. 3, after forming the shorting bar on the base film at block305, the process can proceed to block307. At block307, the touch sensor can be removed from the base film. In some examples, the touch sensor can be removed from the base film using lithography or a physical cutting process, such as a die cutting or laser cutting. For example, touch sensors101can be separated from sheet401inFIG. 4by cutting along cut line403. In this way, cut line403can define the device area of touch sensor200. When removing the touch sensor from the base film at block307, the shorting bar and, in some examples, a portion of the bond pad may be separated from the touch sensor. For example, to remove touch sensor200from the sheet of base film401shown inFIG. 4, a cut can be made along cut line403, thereby separating touch sensor200from shorting bar211and a portion of bond pads205. In other examples, only shorting bars211may be separated from touch sensor200at block307. In either case, separation of shorting bar211from touch sensor200uncouples the contacts209that were previously coupled together by shorting bars211.

Coupling together contacts209of bond pads205using one or more shorting bars211advantageously prevents or reduces the amount of potential difference that can be generated between traces due to static buildup. Moreover, the shorting bars211provide an access point to quickly test touch sensors100or200during manufacture. For example, probes can be attached to shorting bars211coupled to the outer bond pads205of touch sensor200to measure the impedance of the aggregate of drive lines101and associated conductive traces203. If the impedance falls outside an expected range of values, it can quickly be determined if a defect has occurred in the drive lines101and associated conductive traces203. Similarly, the probes can be attached to the shorting bars211coupled to the inner bond pads205of touch sensor200to determine if a defect has occurred in the sense lines103and associated conductive traces203. It should be appreciated that other configurations of shorting bar211are possible and that these configurations can be designed to reduce a potential buildup between selected traces and to allow testing of groups of drive lines101and sense lines103.

One or more of the functions relating to the manufacturing of a touch sensitive device having a shorting bar can be performed by a system similar or identical to system1300shown inFIG. 13. System1300can include instructions stored in a non-transitory computer readable storage medium, such as memory1303or storage device1301, and executed by processor1305. The instructions can also be stored and/or transported within any non-transitory computer readable storage medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “non-transitory computer readable storage medium” can be any medium that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The non-transitory computer readable storage medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like.

System1300can further include manufacturing device1307coupled to processor1305. Manufacturing device1307can be operable to form a touch sensor or other electronic device on a base film and remove the touch sensor or electronic device from the base film, as discussed above with respect toFIG. 3. Processor1305can control manufacturing device1307and its components to generate a desired pattern of conductive traces, drive lines, sense lines, bond pads, and shorting bars in a manner similar or identical to that described above with respect to process300.

It is to be understood that the system is not limited to the components and configuration ofFIG. 13, but can include other or additional components in multiple configurations according to various examples. Additionally, the components of system1300can be included within a single device, or can be distributed between two manufacturing device1307, in some examples, processor1305can be located within manufacturing device1307.

FIG. 14illustrates an exemplary personal device1400, such as a tablet, that can include a touch sensor made using a shorting bar according to various examples.

FIG. 15illustrates another exemplary personal device1500, such as a mobile phone, that can include a touch sensor made using a shorting bar according to various examples.

FIG. 16illustrates an exemplary personal device1600, such as a laptop having a touchpad, that can include a touch sensor made using a shorting bar according to various examples.

FIG. 17illustrates another exemplary personal device1700, such as a touch pad, that can include a touch sensor made using a shorting bar according to various examples.

Therefore, according to the above, some examples of the disclosure are directed to a method comprising: forming a plurality of touch sensors on a sheet of base film, wherein each of the plurality of touch sensors comprises a bond pad; for each of the plurality of touch sensors, forming a shorting bar coupling together two or more contacts of the bond pad; and removing each of the plurality of touch sensors from the sheet of base film, wherein after removing, each touch sensor is separated from its corresponding shorting bar. Additionally or alternatively to one or more of the examples disclosed above, the sheet of base film can comprises cyclo olefin polymer. Additionally or alternatively to one or more of the examples disclosed above, removing each of the plurality of touch sensors from the sheet of base film can be performed using a die cut process. Additionally or alternatively to one or more of the examples disclosed above, removing each of the plurality of touch sensors from the sheet of base film can be performed using a laser cut process. Additionally or alternatively to one or more of the examples disclosed above, removing each of the plurality of touch sensors from the sheet of base film can be performed using lithography. Additionally or alternatively to one or more of the examples disclosed above, the bond pad for each of the plurality of touch sensors can extend beyond an edge of the corresponding touch sensor.

Some examples of the disclosure are directed to a method comprising: forming a touch sensor on a base film, the touch sensor defining a device area on the base film, wherein forming the touch sensor comprises: forming a plurality of sense lines on the base film; forming a plurality of drive lines on the base film; forming one or more bond pads on the base film; and forming a plurality of conductive traces that couple together the one or more bond pads with the plurality of sense lines and the plurality of drive lines; and forming one or more shorting bars coupled to the one or more bond pads, wherein the one or more shorting bars are formed outside the device area of the base film. Additionally or alternatively to one or more of the examples disclosed above, a portion of each of the one or more bond pads can be formed outside the device area of the base film. Additionally or alternatively to one or more of the examples disclosed above, the one or more bond pads can comprise a plurality of bond pads, the one or more shorting bars can comprise one shorting bar, and the one shorting bar can couple together all contacts of the plurality of bond pads. Additionally or alternatively to one or more of the examples disclosed above, the one or more bond pads can comprise a first bond pad coupled to the plurality of drive lines and a second bond pad coupled to the plurality of sense lines, and the one or more shorting bars can comprise a first shorting bar coupling together contacts of the first bond pad and a second shorting bar coupling together contacts of the second bond pad. Additionally or alternatively to one or more of the examples disclosed above, the one or more bond pads can comprise a first plurality of bond pads coupled to the plurality of drive lines and a second plurality of bond pads coupled to the plurality of sense lines, and the one or more shorting bars can comprise a first shorting bar coupling together contacts of the first plurality of bond pads and a second shorting bar coupling together contacts of the second plurality of bond pads.

Some examples of the disclosure are directed to a method for manufacturing a touch sensor, the method comprising: depositing a first mask layer on a base film, wherein the base film comprises a layer of indium tin oxide and a layer of copper; removing a portion of the first mask to define a plurality of drive lines, a plurality of sense lines, a plurality of bond pads, a plurality of conductive traces coupling together the plurality of sense lines and the plurality of drive lines with the plurality of bond pads, and one or more shorting bars coupled to the plurality of bond pads; etching, using the first mask layer, a first portion of the layer of copper and a first portion of the layer of indium tin oxide to form the plurality of drive lines, the plurality of sense lines, the plurality of bond pads, the plurality of conductive traces, and the one or more shorting bars; removing the first mask layer; depositing a second mask layer on the base film over the plurality of conductive traces, the plurality of bond pads, and the one or more shorting bars; etching, using the second mask, a second portion of the layer of copper located above the plurality of drive lines and the plurality of sense lines; removing the second mask layer; and removing the touch sensor from the base film, wherein after removing the touch sensor from the base film, the one or more shorting bars are separated from the touch sensor. Additionally or alternatively to one or more of the examples disclosed above, removing the touch sensor from the base film can comprise cutting the touch sensor along a line intersecting the plurality of bond pads. Additionally or alternatively to one or more of the examples disclosed above, the plurality of bond pads can comprise: a first bond pad coupled to a first end of the plurality of drive lines; a second bond pad coupled a second end of the plurality of drive lines; a third bond pad coupled to a first end of the plurality of sense lines; and a fourth bond pad coupled to a second end of the plurality of sense lines. Additionally or alternatively to one or more of the examples disclosed above, the one or more shorting bars can comprise: a first shorting bar coupled to the first bond pad; a second shorting bar coupled to the second bond pad; a third shorting bar coupled to the third bond pad; and a fourth shorting bar coupled to the fourth bond pad. Additionally or alternatively to one or more of the examples disclosed above, the method can further comprise, before removing the touch sensor from the base film: measuring an impedance of the plurality of drive lines using the first shorting bar and the second shorting bar; and measuring an impedance of the plurality of sense lines using the third shorting bar and the fourth shorting bar.

Some examples of the disclosure are directed to a touch sensor comprising: a plurality of sense lines; a plurality of drive lines; one or more bond pads; and a plurality of conductive traces that couple together the one or more bond pads with the plurality of sense lines and the plurality of drive lines, wherein the one or more bond pads extend to an edge of the touch sensor. Additionally or alternatively to one or more of the examples disclosed above, the one or more bond pads can comprise indium tin oxide. Additionally or alternatively to one or more of the examples disclosed above, the one or more bond pads can comprise copper. Additionally or alternatively to one or more of the examples disclosed above, the touch sensor can be incorporated within one of a phone, portable media player, tablet computing device, or touch pad. Additionally or alternatively to one or more of the examples disclosed above, the one or more bond pads can have been separated from a shorting bar.