Double-sided touch sensitive panel and flex circuit bonding

• US 20080158181A1
• Filed: 01/03/2007
• Published: 07/03/2008
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Hotelling, Steve Porter, Hamblin, Mark Arthur
• Granted Patent: US 8,026,903 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: H01H 2001/5816 Connections to flexible or curved printed circuit boards
• CPC Class Codes: H01R 12/62 connecting to rigid printed circuits or like structures
• CPC Class Codes: H01R 4/04 using electrically conductive adhesives
• CPC Class Codes: H01R 43/205 with a panel or printed circuit board
• CPC Class Codes: H05K 2203/0278 Flat pressure, e.g. for connecting terminals with anisotropic conductive adhesive
• CPC Class Codes: H05K 2203/1121 Cooling, e.g. specific areas of a PCB being cooled during reflow soldering details related to cooling of mounted components H05K1/0203
• CPC Class Codes: H05K 2203/1572 Processing both sides of a PCB by the same process; Providing a similar arrangement of components on both sides; Making interlayer connections from two sides
• CPC Class Codes: H05K 3/323 by applying an anisotropic conductive adhesive layer over an array of pads
• CPC Class Codes: H05K 3/361 Assembling flexible printed circuits with other printed circuits
• CPC Class Codes: Y10T 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A multi-touch sensor panel can be created using a substrate with column and row traces formed on either side. Metal traces running along the border of the substrate can be used to bring the row traces to the same edge as the column traces. A single flex circuit can be fabricated to connect to the rows and columns on directly opposing sides. Flex printed circuits can be bonded to directly opposing attachment areas of a substrate by cooling one side of the substrate while bonding the other. In addition, “coverlay” material extending over right-angled traces on the flex circuit ensure that those traces do not get shorted should conductive bonding material get squeezed out during bonding. Furthermore, a spacer is placed at the distal end of the flex circuit to apply even bonding pressure over the entire flex circuit attachment area during bonding.

Claims

1. A method for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

applying a bonding head to a first side of the substrate to create a first bond between a first flex circuit portion and conductors on a first attachment area of the first side, the bonding head applying heat and pressure directly to the first flex circuit portion; and

applying a cooling head to a second side of the substrate to maintain a previously formed second bond between a second flex circuit portion and conductors on a second attachment area of the second side;

wherein the first attachment area and the second attachment area are on directly opposing sides of the substrate.

2. The method of claim 1, wherein the applying of the bonding head and the cooling head occur at about the same time.

3. The method of claim 1, further comprising maintaining the previously formed second bond by drawing heat generated by the bonding head away from the second bond.

4. A method for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

forming a first attachment area on a first side of the substrate;

forming a second attachment area on a second side of the substrate, the first and second attachment areas directly opposing each other;

applying a bonding head to the first attachment area of the first side to create a first bond between a first flex circuit portion and the first attachment area of the first side, the bonding head applying heat and pressure directly to the first flex circuit portion; and

applying a cooling head to the second attachment area of the second side to maintain a previously formed second bond between a second flex circuit portion and the second attachment area of the second side.

5. The method of claim 4, wherein the applying of the bonding head and the cooling head occur at about the same time.

6. The method of claim 4, further comprising maintaining the previously formed second bond by drawing heat generated by the bonding head away from the second bond.

7. A method for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

applying a first bonding head to a first side of the substrate to create a first bond between a first flex circuit portion and conductors in a first area of a first attachment area of the first side, the first bonding head shaped for applying heat and pressure to the first area; and

applying a second bonding head to a second side of the substrate to create a second bond between a second flex circuit portion and conductors in a second area of a second attachment area of the second side, the second bonding head shaped for applying heat and pressure to the second area;

wherein the first attachment area and the second attachment area are on directly opposing sides of the substrate.

8. The method of claim 7, wherein the applying of the first bonding head and the second bonding head occur at about the same time.

9. A method for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

forming a first attachment area on a first side of the substrate having conductors in a first area and forming a first flex circuit portion corresponding to the conductors on the first attachment area;

forming a second attachment area on a second side of the substrate having conductors in a second area and forming a second flex circuit portion corresponding to the conductors on the second attachment area, the first and second attachment areas directly opposing each other but the first and second areas on non-opposing sides;

shaping a first bonding head to apply heat and pressure to the first area;

shaping a second bonding head to apply heat and pressure to the second area;

applying the first bonding head to the first side of the substrate to create a first bond between the first flex circuit portion and the conductors in the first area on the first attachment area of the first side; and

applying the second bonding head to the second side of the substrate to create a second bond between the second flex circuit portion and the conductors in the second area on the second attachment area of the second side.

10. The method of claim 9, wherein the applying of the first bonding head and the second bonding head occur at about the same time.

11. A method for bonding a flex circuit to a substrate, the flex circuit having a ribbon area and an attachment area, the method comprising:

applying coverlay to cover traces on the ribbon area and angled traces on the attachment area;

forming a spacer at a distal end of the attachment area, the spacer and coverlay on non-opposing sides of the flex circuit; and

applying a bonding head to apply heat and pressure to the attachment area to bond the attachment area to the substrate.

12. The method of claim 11, further comprising bonding a portion of the coverlay extending over the angled traces on the attachment area to the substrate.

13. A method for bonding a flex circuit to a substrate, the flex circuit have a ribbon area and an attachment area, the method comprising:

sealing angled traces on the attachment area;

using a spacer at a distal end of the attachment area to force the distal end of the attachment area down to the substrate, the spacer and coverlay on non-opposing sides of the flex circuit; and

applying a bonding head to apply heat and pressure to the attachment area to bond the attachment area to the substrate.

14. A system for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

a bonding head for creating a first bond between a first flex circuit portion and conductors on a first attachment area of a first side of the substrate, the bonding head configured for applying heat and pressure directly to the first flex circuit portion; and

a cooling head configured in a directly opposing orientation as compared to the bonding head for maintaining a previously formed second bond between a second flex circuit portion and conductors on a second attachment area of a second side of the substrate;

wherein the first attachment area and the second attachment area are on directly opposing sides of the substrate.

15. The system of claim 14, the bonding head and the cooling head configured for applying pressure to the substrate at about the same time.

16. The system of claim 14, the cooling head configured for maintaining the previously formed second bond by drawing heat generated by the bonding head away from the second bond.

17. A system for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

a substrate having a first attachment area on a first side and a second attachment area on a second side, the first and second attachment areas directly opposing each other;

a bonding head for creating a first bond between a first flex circuit portion and the first attachment area of the first side, the bonding head applying heat and pressure directly to the first flex circuit portion; and

a cooling head for maintaining a previously formed second bond between a second flex circuit portion and the second attachment area of the second side.

18. The system of claim 17, the bonding head and the cooling head configured for applying pressure to the substrate at about the same time.

19. The system of claim 17, the cooling head configured for maintaining the previously formed second bond by drawing heat generated by the bonding head away from the second bond.

20. A system for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

a first bonding head for creating a first bond between a first flex circuit portion and conductors in a first area of a first attachment area of a first side of the substrate, the first bonding head shaped for applying heat and pressure to the first area; and

a second bonding for creating a second bond between a second flex circuit portion and conductors in a second area of a second attachment area of a second side of the substrate, the second bonding head shaped for applying heat and pressure to the second area;

wherein the first attachment area and the second attachment area are on directly opposing sides of the substrate.

21. The system of claim 20, the first bonding head and the second bonding head configured for applying pressure to the substrate at about the same time.

22. A system for bonding flex circuits to attachment areas on directly opposing sides of a substrate, comprising:

a substrate having a first attachment area on a first side and a second attachment area on a second side, the first attachment area having conductors in a first area and the second attachment area having conductors in a second area, the first and second attachment areas directly opposing each other but the first and second areas on non-opposing sides of the substrate;

a first flex circuit portion configured to correspond with the conductors on the first attachment area;

a second flex circuit portion configured to correspond with the conductors on the second attachment area;

a first bonding head shaped to apply heat and pressure to the first area to create a first bond between the first flex circuit portion and the conductors in the first area on the first attachment area of the first side; and

a second bonding head shaped to apply heat and pressure to the second area to create a second bond between the second flex circuit portion and the conductors in the second area on the second attachment area of the second side.

23. The system of claim 22, the first bonding head and the second bonding head configured for applying pressure to the substrate at about the same time.

24. A flex circuit for bonding to a substrate, comprising:

a ribbon area;

an attachment area connected to the ribbon area;

coverlay applied over traces on the ribbon area and angled traces on the attachment area;

a spacer formed at a distal end of the attachment area, the spacer and coverlay on non-opposing sides of the flex circuit and configured for enabling a bonding head to apply heat and pressure to the attachment area to bond the attachment area to the substrate.

25. The flex circuit of claim 24, a portion of the coverlay extending over the angled traces on the attachment area configured for bonding to the substrate.

26. The flex circuit of claim 24, further comprising a sensor panel bonded to the flex circuit, the sensor panel including the substrate.

27. The flex circuit of claim 26, further comprising a computing system that incorporates the sensor panel.

28. The flex circuit of claim 27, further comprising a mobile telephone that incorporates the computing system.

29. The flex circuit of claim 27, further comprising a digital audio player that incorporates the computing system.

30. A flex circuit for bonding to a substrate, comprising:

a ribbon area;

an attachment area connected to the ribbon area;

coverlay applied over traces on the ribbon area and angled traces on the attachment area;

a spacer formed at a distal end of the attachment area to force the distal end of the attachment area down to the substrate, the spacer and coverlay on non-opposing sides of the flex circuit and configured for enabling a bonding head to apply heat and pressure to the attachment area to bond the attachment area to the substrate.

31. The flex circuit of claim 30, further comprising a sensor panel bonded to the flex circuit, the sensor panel including the substrate.

32. The flex circuit of claim 31, further comprising a computing system that incorporates the sensor panel.

33. The flex circuit of claim 32, further comprising a mobile telephone that incorporates the computing system.

34. The flex circuit of claim 32, further comprising a digital audio player that incorporates the computing system.

35. A capacitive touch sensor panel, comprising:

a substrate formed from a dielectric material;

a first set of non-overlapping traces of conductive material formed on a first side of the substrate and arranged along a first dimension of a two-dimensional coordinate system; and

a second set of non-overlapping traces of the conductive material formed on a second side of the substrate and arranged along a second dimension of the two-dimensional coordinate system;

wherein sensors are formed at locations at which the first set of traces pass over the second set of traces while separated by the dielectric material of the substrate.

36. The capacitive touch sensor panel of claim 35, further comprising:

a first connector area on the first side at a first edge of the substrate, the first connector area having first conductors coupled to the first set of traces; and

a second connector area on the second side at the first edge of the substrate, the second connector area having second conductors coupled to the second set of traces.

37. The capacitive touch sensor panel of claim 36, wherein the first and second conductors are located on the first and second sides at locations within the first and second connector areas that are not directly opposing each other.

38. The capacitive touch sensor panel of claim 36, further comprising metal traces running along second and third edges of the substrate and connected to the second set of traces and the second conductors for routing the second set of traces to the second connector area, the second and third edges adjacent to the first edge of the substrate.

39. The capacitive touch sensor panel of claim 36, further including a flex circuit for connecting to the first and second connector areas on the substrate, the flex circuit comprising:

a first flex circuit portion for forming an electrical connection with the first conductors on the first connector area; and

a second flex circuit portion for forming an electrical connection with the second conductors on the second connector area.

40. The capacitive touch sensor panel of claim 39, the flex circuit further comprising a circuit area connected between the first flex circuit portion and the second flex circuit portion, the circuit area for supporting one or more circuits and making electrical connections with the first and second connector areas.

41. The capacitive touch sensor panel of claim 35, further comprising a computing system that incorporates the sensor panel.

42. The capacitive touch sensor panel of claim 41, further comprising a mobile telephone that incorporates the computing system.

43. The capacitive touch sensor panel of claim 41, further comprising a digital audio player that incorporates the computing system.

44. A mobile telephone having a capacitive touch sensor panel, the capacitive touch sensor panel comprising:

a substrate formed from a dielectric material;

a first set of non-overlapping traces of conductive material formed on a first side of the substrate and arranged along a first dimension of a two-dimensional coordinate system; and

a second set of non-overlapping traces of the conductive material formed on a second side of the substrate and arranged along a second dimension of the two-dimensional coordinate system;

wherein sensors are formed at locations at which the first set of traces pass over the second set of traces while separated by the dielectric material of the substrate.

45. A digital audio player having a capacitive touch sensor panel, the capacitive touch sensor panel comprising:

a substrate formed from a dielectric material;

a first set of non-overlapping traces of conductive material formed on a first side of the substrate and arranged along a first dimension of a two-dimensional coordinate system; and

a second set of non-overlapping traces of the conductive material formed on a second side of the substrate and arranged along a second dimension of the two-dimensional coordinate system;

wherein sensors are formed at locations at which the first set of traces pass over the second set of traces while separated by the dielectric material of the substrate.

46. A method for forming a capacitive touch sensor panel, comprising:

forming and arranging a first set of non-overlapping traces of conductive material on a first side of a dielectric substrate along a first dimension of a two-dimensional coordinate system;

forming and arranging a second set of non-overlapping traces of the conductive material formed on a second side of the substrate along a second dimension of the two-dimensional coordinate system; and

forming sensors at locations at which the first set of traces pass over the second set of traces while separated by the dielectric material of the substrate.

47. The method of claim 46, further comprising:

reserving a first connector area on the first side at a first edge of the substrate, forming first conductors in the first connector area and connecting the first conductors to the first set of traces; and

reserving a second connector area on the second side at the first edge of the substrate, forming second conductors in the second connector area and connecting the second conductors to the second set of traces.

48. The method of claim 47, further comprising locating the first and second conductors on the first and second sides at locations within the first and second connector areas that are not directly opposing each other.

49. The method of claim 47, further comprising forming metal traces along second and third edges of the substrate and connecting the metal traces to the second set of traces and the second conductors for routing the second set of traces to the second connector area, the second and third edges adjacent to the first edge of the substrate.

50. The method of claim 47, further comprising:

connecting a first flex circuit portion of a flex circuit to the first conductors on the first connector area; and

connecting a second flex circuit portion of the flex circuit to the second conductors on the second connector area.

51. The method of claim 50, further comprising connecting a circuit area between the first flex circuit portion and the second flex circuit portion, the circuit area for supporting one or more circuits and making electrical connections with the first and second connector areas.

52. A method for fabricating a capacitive touch sensor panel, comprising:

supporting a dielectric substrate on one or more conveying members of fabrication machinery;

depositing a layer of conductive material on a first side of a dielectric substrate and etching the conductive material to form a first set of non-overlapping traces along a first dimension of a two-dimensional coordinate system;

depositing a protective coating of photoresist over the first set of traces on the first side of the substrate;

reversing an orientation of the substrate on the one or more conveying members of the fabrication machinery;

depositing a layer of conductive material on a second side of the dielectric substrate and etching the conductive material to form a second set of non-overlapping traces along a second dimension of the two-dimensional coordinate system; and

removing the photoresist on the first side of the substrate.

53. The method of claim 52, further comprising, prior to removing the photoresist on the first side of the substrate:

depositing a protective coating of photoresist over the second set of traces on the second side of the substrate while leaving edges of the second side of the substrate exposed;

depositing a metal layer over the exposed edges of the second side and etching the metal layer to form metal traces that connect to the second set of traces; and

removing the photoresist on the first and second sides of the substrate.

54. A method for fabricating a capacitive touch sensor panel, comprising:

sputtering conductive material on first and second sides of a dielectric substrate;

applying a temporary protective film over the conductive material sputtered onto the first side of the substrate;

supporting the dielectric substrate first side down on one or more conveying members of fabrication machinery;

depositing a protective coating of photoresist over the conductive material sputtered onto the second side of the substrate, and patterning the photoresist;

supporting the dielectric substrate second side down on the one or more conveying members of the fabrication machinery;

removing the temporary protective film from the first side of the substrate;

depositing a protective coating of photoresist over the conductive material sputtered onto the first side of the substrate, and patterning the photoresist;

etching the conductive material on the first and second sides of the substrate; and

stripping off the photoresist on the first and second sides of the substrate.