Double-sided touch sensitive panel and flex circuit bonding

• US 7,999,795 B2
• Filed: 01/05/2011
• Issued: 08/16/2011
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hamblin, Mark Arthur, Hotelling, Steve Porter
• Primary Examiner(s): Wang; Quan-Zhen
• Assistant Examiner(s): Nguyen; Jennifer
• Application Number:
  US12/985,239
• Publication Number:
  US 20110094993A1
• Time in Patent Office: 223 Days
• Field of Search: 345173-179, 178 1801- 1806
• 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 fabricating a capacitive touch sensor panel, comprising:

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 with respect to 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.

2. The method of claim 1, 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.

4. The method of claim 1, wherein the depositing of the layer of the conductive material on the second side of the dielectric substrate and etching the conductive material to form the set of non-overlapping traces further comprises:

applying a first photoresist to an interior region of the second side while leaving edge regions exposed, depositing a metal layer, and stripping off the first photoresist to leave the metal in the edge regions;

depositing the layer of conductive material on the second side;

applying and patterning a second photoresist on the second side to form a mask for the set of non-overlapping traces; and

etching the layer of conductive material and metal layer to form the set of non-overlapping traces.

3. 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;

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

reversing an orientation of the substrate with respect to 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.