Liquid coverlays for flexible printed circuit boards

Patent metadata

Field	Value
Publication number	US-9670306-B2
Application number	US-201013256619-A
Country	US
Kind code	B2
Filing date	Mar 16, 2010
Priority date	Mar 16, 2009
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

The present invention relates to curable liquid coverlay compositions comprising polyamideimide resins for use in curable compositions for use as protective coverlay coatings for metal clad laminate materials in electronic components, such as flexible circuit boards. In particular, the invention relates to liquid coverlay compositions comprising polyamideimides having a terminal isocyanate group blocked by a thermally-dissociatable isocyanate-blocking group and the use of such compositions in preparation of flexible electronic components.

First claim

The invention claimed is:

1. A thermal-curing coverlay composition for a flexible printed circuit board substrate, comprising a polyamideimide having a terminal isocyanate group blocked by a thermally-dissociatable isocyanate-blocking group, and an aprotic solvent; wherein the molar ratio of diisocyanate to isocyanate-blocking agent is from 10:0.1 to 10:2.

2. The composition of claim 1 , wherein the polyamideimide having a terminal isocyanate group blocked by a thermally-dissociatable isocyanate-blocking group is the reaction product of (i) a polyamideimide having a terminal isocyanate group and (ii) an aliphatic amide.

3. The composition of claim 2 , wherein the aliphatic amide is a 5 to 8-membered lactam optionally substituted with one or more C 1 -C 4 alkyl groups.

4. The composition of claim 3 , wherein the 5 to 8-membered lactam is ∈-caprolactam.

5. The composition of claim 1 , wherein the polyamideimide having a terminal isocyanate group blocked by a thermally-dissociatable isocyanate-blocking group has the formula (I):
[BL]-C(O)-([A]-[B]) n —OH   (I)

wherein: ([A]-[B]) n is a polyamideimide unit in which n is at least 4; and [BL] is a thermally-dissociatable isocyanate-blocking group.

6. The composition of claim 5 , wherein [BL] is —N(R 1 )—C(O)R 2 , wherein either R 1 and R 2 are each independently selected from C 1 -C 6 alkyl; or R 1 , R 2 and the amide group to which they are attached together form a 5 to 8-membered lactam ring, optionally substituted with one or more C 1 -C 4 alkyl groups.

7. The composition of claim 6 , wherein R 1 , R 2 and the nitrogen atom and carbonyl group to which they are attached together forms a 5 to 8-membered lactam ring, optionally substituted with one or more methyl groups.

8. The composition of claim 1 , wherein the thermally-dissociatable isocyanate-blocking group dissociates at a temperature in the range of from 100° C. to 250° C.

9. The composition of claim 8 , wherein the thermally-dissociatable isocyanate-blocking group dissociates at a temperature in the range of from 140° C. to 200° C.

10. The composition of claim 1 , wherein the polyamideimide having a terminal isocyanate group is the reaction product of a diisocyanate and a carboxylic acid functional group-containing carboxylic acid anhydride.

11. The composition of claim 1 having a viscosity of less than 30 Pas at 25° C.

12. The composition of claim 11 having a viscosity of less than 20 Pas at 25° C.

Assignees

• Hall Stephen Anthony
• Davis Richard Charles
• Ford Simon Richard
• Klaus Matthias
• Ognibeni Karl-Heinz
• Sun Chemical Corp

Inventors

• Hall Stephen Anthony
• Davis Richard Charles
• Ford Simon Richard
• Klaus Matthias
• Ognibeni Karl-Heinz

Classifications

• C08G18/8074

  Lactams · CPC title

• C08G73/14

  Polyamide-imides · CPC title

• C08L63/00

  Compositions of epoxy resins; Compositions of derivatives of epoxy resins · CPC title

• H01B3/306

  Polyimides or polyesterimides · CPC title

• H05K3/287

  Photosensitive compositions · CPC title