Liquid-based pressure sensitive adhesive for grounding applications

• US 9,258,906 B2
• Filed: 04/15/2013
• Issued: 02/09/2016
• Est. Priority Date: 04/15/2013
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Krogdahl, James R., Pope, Benjamin J., Pyper, Dennis R., Merz, Nicholas G. L., Myers, Scott A.
• Primary Examiner(s): Chan, Sing P
• Application Number:
  US13/863,264
• Publication Number:
  US 20140308465A1
• Time in Patent Office: 1,030 Days
• Field of Search: 156/247, 156/272.2, 156/273.3, 156/274.8, 156/275.3, 156/275.5, 156/275.7, 156/307.1, 156/307.3, 156/307.5
• US Class Current: 1/1
• CPC Class Codes: C09J 2203/326 for bonding electronic components such as wafers, chips or semiconductors
• CPC Class Codes: C09J 2301/302 the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
• CPC Class Codes: C09J 2301/416 use of irradiation
• CPC Class Codes: C09J 5/00 Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers
• 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: H05K 3/386 by the use of an organic polymeric bonding layer, e.g. adhesive
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

An electronic device may be provided with electronic device structures such as housing structures, antenna structures, printed circuits, and structures associated with electrical components. The structures may be attached to each other using adhesive. A liquid pressure sensitive adhesive precursor material is deposited onto one or more surfaces of structures to be bonded. Light or heat can be applied to cure the liquid adhesive material and form pressure sensitive adhesive layers. During curing, chemical bonds are formed between the adhesive material and the structures. Assembly equipment may press the structures together to form pressure sensitive adhesive bonds that can be reworked without disturbing the chemically bonded portions of the adhesive material. The pressure sensitive adhesive may include conductive particles for forming conductive paths.

Claims

1. A method for assembling structures in an electronic device, comprising:

applying liquid pressure sensitive adhesive precursor material to a first structure in the electronic device;

curing the liquid pressure sensitive adhesive precursor material on the first structure to form a first pressure sensitive adhesive layer;

applying liquid pressure sensitive adhesive precursor material to a second structure in the electronic device;

curing the liquid pressure sensitive adhesive precursor material on the second structure to form a second pressure sensitive adhesive layer; and

pressing together the first and second pressure sensitive adhesive layers to attach the first and second structures.

2. The method defined in claim 1 wherein the first and second pressure sensitive adhesive layers comprise conductive pressure sensitive adhesive.

3. The method defined in claim 2 wherein the first structure comprises a metal electronic device housing and wherein curing the liquid pressure sensitive adhesive precursor comprises curing the liquid pressure sensitive adhesive precursor material on the metal electronic device housing.

4. The method defined in claim 1 wherein the first structure includes first metal traces, wherein the second structure includes second metal traces, and wherein pressing together the first and second pressure sensitive adhesive layers comprises forming a conductive pressure sensitive adhesive joint that shorts the first metal traces to the second metal traces.

5. The method defined in claim 1 wherein curing the liquid pressure sensitive adhesive precursor material comprises applying ultraviolet light to the liquid pressure sensitive adhesive precursor material.

6. The method defined in claim 1 wherein curing the liquid pressure sensitive adhesive precursor material comprises heating the liquid pressure sensitive adhesive precursor material to a temperature that is elevated above room temperature by at least 40°

C.

7. The method defined in claim 1 wherein pressing together the first and second pressure sensitive adhesive layers forms a pressure-sensitive-adhesive-to-pressure-sensitive adhesive interface, the method further comprising pulling apart the first and second pressure sensitive adhesive layers along the pressure-sensitive-adhesive-to-pressure-sensitive adhesive interface without removing the first pressure sensitive adhesive layer from the first structure and without removing the second pressure sensitive adhesive layer from the second structure.

8. The method defined in claim 1 wherein the first structure comprises a flexible printed circuit, wherein the second structure comprises a metal housing, wherein the first and second pressure sensitive adhesive layers comprise conductive pressure sensitive adhesive, and wherein pressing together the first and second pressure sensitive adhesive layers comprises forming a conductive pressure sensitive adhesive joint that shorts metal traces in the flexible printed circuit to the metal housing.

9. The method defined in claim 1 wherein curing the liquid pressure sensitive adhesive precursor material on the first structure comprises forming chemical bonds between the first pressure sensitive adhesive layer and the first structure and wherein curing the liquid pressure sensitive adhesive precursor material on the second structure comprises forming chemical bonds between the second pressure sensitive adhesive layer and the second structure.

10. A method, comprising:

depositing a conductive liquid pressure sensitive adhesive precursor material on a first conductive structure;

curing the deposited liquid pressure sensitive adhesive precursor material on the first conductive structure to form a conductive pressure sensitive adhesive layer that is chemically bonded to the first conductive structure; and

shorting a second conductive structure to the first conductive structure through the conductive pressure sensitive adhesive layer, wherein the second conductive structure comprises a ground structure and wherein shorting the second conductive structure to the first conductive structure comprises grounding the first conductive structure to the conductive ground structure through the conductive pressure sensitive adhesive layer.

11. The method defined in claim 10 wherein shorting the second conductive structure comprises pressing a metal trace on a flexible printed circuit against the conductive pressure sensitive adhesive layer.

12. The method defined in claim 11 wherein depositing the conductive liquid pressure sensitive adhesive comprises screen printing the conductive liquid pressure sensitive adhesive precursor material.

13. The method defined in claim 12 wherein the flexible printed circuit includes an antenna formed from metal structures that are at least partly covered with the deposited liquid pressure sensitive adhesive material and wherein curing the deposited liquid pressure sensitive adhesive precursor material comprises applying light to the deposited liquid pressure sensitive adhesive precursor material on the metal structures.

14. The method defined in claim 13 further comprising:

depositing conductive liquid pressure sensitive adhesive precursor material on the second conductive structure; and

curing the deposited liquid pressure sensitive adhesive precursor material on the second conductive structure to form a conductive pressure sensitive adhesive layer that is chemically bonded to the second conductive structure, wherein shorting the second conductive structure to the first conductive structure comprises grounding the first conductive structure to the conductive ground structure through the conductive pressure sensitive adhesive layers on the first and second conductive structures.