Recyclable Circuit Assembly

• US 20130188323A1
• Filed: 01/25/2013
• Published: 07/25/2013
• Est. Priority Date: 01/25/2012
• Status: Active Grant

• Current Assignee: In2tec Limited, NPL Management Limited (Serco Group PLC), Gwent Electronic Materials Ltd. (Sun Chemical Corporation)
• Original Assignee: Gwent Electronic Materials Ltd. (Sun Chemical Corporation)
• Inventors: Hunt, Christopher, Lewison, John, Pittson, Robin
• Granted Patent: US 9,706,693 B2
• Time in Patent Office: Days
• US Class Current: 361/750
• CPC Class Codes: H05K 1/0277 Bendability or stretchability details H05K1/038, H05K3/4691 take precedence
• CPC Class Codes: H05K 1/181 associated with surface mounted components
• CPC Class Codes: H05K 13/00 Apparatus or processes specially adapted for manufacturing or adjusting assemblages of electric components
• CPC Class Codes: H05K 2201/2009 Reinforced areas, e.g. for a specific part of a flexible printed circuit
• CPC Class Codes: H05K 2203/0769 Dissolving insulating materials, e.g. coatings, not used for developing resist after exposure
• CPC Class Codes: H05K 2203/0776 Uses of liquids not otherwise provided for in H05K2203/0759 - H05K2203/0773
• CPC Class Codes: H05K 2203/088 Using a vapour or mist, e.g. cleaning using water vapor
• CPC Class Codes: H05K 2203/176 Removing, replacing or disconnecting component; Easily removable component thermal arrangements, e.g. to prevent overheating H05K1/0201
• CPC Class Codes: H05K 2203/178 Demolishing, e.g. recycling, reverse engineering, destroying for security purposes; Using biodegradable materials
• CPC Class Codes: H05K 3/0058 Laminating printed circuit boards onto other substrates, e.g. metallic substrates H05K1/0281 takes precedence
• CPC Class Codes: H05K 3/22 Secondary treatment of printed circuits H05K3/1283 takes precedence; embedding circuits in grooves by pressure H05K3/107
• CPC Class Codes: H05K 3/321 by conductive adhesives
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 156/1111 Using solvent during delaminating [e.g., water dissolving adhesive at bonding face during delamination, etc.]
• CPC Class Codes: Y10T 156/1153 Temperature change for delamination [e.g., heating during delaminating, etc.]

Abstract

An electronic circuit assembly comprises a substrate and circuit components attached to the substrate by means of an electrically conductive adhesive, wherein the adhesive is releasable under predetermined release conditions, whereby to enable the circuit components to be removed from the substrate for recovery or re-use.

Claims

1. Electronic circuit assembly comprising a substrate and circuit components attached to the substrate by means of an electrically conductive adhesive, wherein the adhesive is releasable under predetermined release conditions, whereby to enable the circuit components to be removed from the substrate for recovery or re-use.

2. Electronic circuit assembly as claimed in claim 1, wherein the circuit components are located on a first surface of the substrate, and are attached by means of the adhesive to electrical connections provided on the first surface of the substrate, and wherein the adhesive is arranged on the substrate in a circuit pattern whereby to make electrical connections between the circuit components.

3. Electronic circuit assembly as claimed in claim 1, wherein the substrate comprises one or more layers of conductive tracking provided on its surface, and the circuit components are secured by the adhesive to the conductive tracking to form an electrical circuit.

4. Electronic circuit assembly as claimed in claim 3, wherein the conductive tracking is formed from conductive ink.

5. Electronic circuit assembly as claimed in claim 1, wherein the substrate comprises a flexible substrate formed from, for example, polyimide, PEN or PET, and the flexible substrate comprises integrally formed electrical components, e.g. resistances, switches or connection points.

6. Electronic circuit assembly as claimed in claim 1, wherein the substrate comprises a flexible substrate to which the circuit components are secured by means of the electrically conductive adhesive, wherein the flexible substrate is secured to a rigid substrate formed from, for example, polyester, by means of a further releasable, preferably non-conductive, adhesive whereby to further enable the flexible substrate to be removed from the rigid substrate under predetermined release conditions.

7. Electronic circuit assembly as claimed in claim 6, wherein the release conditions of the conductive adhesive are the same as those of the further adhesive, whereby to enable simultaneous separation of the circuit components and the rigid substrate from the flexible substrate.

8. Electronic circuit assembly as claimed in claim 6, wherein the release conditions of the conductive adhesive are different from those of the further adhesive, whereby to enable separation of the circuit components and the rigid substrate from the flexible substrate to take place separately.

9. Electronic circuit assembly as claimed in claim 1, wherein the adhesive is selected such that the release conditions comprise heating and/or exposure to water or another solvent.

10. Electronic circuit assembly as claimed in claim 9, wherein the adhesive, e.g. polymer based thermoplastic adhesive and/or cross-link thermosetting cyclic amine adhesive, is selected such that the release conditions comprise heating to a temperature of 80-100°

C., or immersion of the assembly in a hot water bath.

16. Method of manufacturing an electronic circuit assembly as claimed in claim 1, comprising:

providing a substrate;

applying an electrically conductive adhesive to the substrate, for example by screen printing, stencil printing, bar coating, or other suitable dot dispense technique,

attaching circuit components to the adhesive; and

curing the adhesive,

wherein the adhesive is releasable under predetermined release conditions, whereby to enable the circuit components to be removed from the substrate for recovery or re-use.

11. Electronic circuit assembly comprising an electrical circuit integrally formed on a flexible substrate, the flexible substrate being attached to a rigid substrate by means of an adhesive, wherein the adhesive is releasable under predetermined release conditions, whereby to enable the electrical circuit to be removed from the rigid substrate for recovery or re-use.

12. Method of disassembling an electronic circuit assembly, the circuit assembly comprising a substrate and circuit components attached to the substrate by means of an electrically conductive adhesive, the adhesive being releasable under predetermined release conditions, whereby to enable the circuit components to be removed from the substrate for recovery or re-use, the method comprising exposing the assembly to the release conditions of the releasable adhesive, for example an elevated temperature and or a solvent not encountered during normal operation, and sweeping the circuit components from the substrate.

13. Method as claimed in claim 12, wherein the substrate of the circuit assembly comprises a flexible substrate to which the circuit components are secured by means of the electrically conductive adhesive, and the flexible substrate is secured to a rigid substrate by means of a further releasable, preferably non-conductive, adhesive whereby to further enable the flexible substrate to be removed from the rigid substrate under predetermined release conditions, and the method further comprises exposing the assembly to the release conditions of the further adhesive and separating the flexible substrate from the rigid substrate.

14. Method as claimed in claim 13, comprising peeling the flexible substrate from the rigid substrate with a sufficiently small radius of curvature to simultaneously cause the circuit components to be released from the flexible substrate.

15. Method as claimed in claim 12, comprising applying a jet of hot water or steam to the assembly to both heat the adhesive(s) to the required separation temperature and cause physical separation of the components from the substrate.