Encapsulated wire circuit board

• US 5,098,766 A
• Filed: 05/24/1991
• Issued: 03/24/1992
• Est. Priority Date: 03/03/1989
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Gelorme, Jeffrey D., Skarvinko, Eugene R.
• Primary Examiner(s): McCamish, Marion E.
• Assistant Examiner(s): KOECKERT JR, ARTHUR
• Application Number:
  US07/705,601
• Time in Patent Office: 305 Days
• Field of Search: 428/138, 428/209, 428/415, 428/416, 428/901
• US Class Current: 428/138
• CPC Class Codes: C08F 283/00 Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
• CPC Class Codes: C08G 59/08 from phenol-aldehyde condensates
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 2666/22 Macromolecular compounds not provided for in C08L2666/16 - C08L2666/20
• CPC Class Codes: C09J 163/10 Epoxy resins modified by unsaturated compounds
• CPC Class Codes: C09J 171/00 Adhesives based on polyethers obtained by reactions forming an ether link in the main chain based on polyacetals C09J159/00; based on epoxy resins C09J163/00; based on polythioether-ethers C09J181/02; based on polyethersulfones C09J181/06; Adhesives based on derivatives of such polymers
• CPC Class Codes: C09J 4/06 Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
• CPC Class Codes: H05K 2201/10287 Metal wires as connectors or conductors
• CPC Class Codes: H05K 3/103 by bonding or embedding conductive wires or strips
• CPC Class Codes: H05K 3/287 Photosensitive compositions
• CPC Class Codes: H05K 3/386 by the use of an organic polymeric bonding layer, e.g. adhesive
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 428/24331 including nonapertured component
• CPC Class Codes: Y10T 428/24917 including metal layer
• CPC Class Codes: Y10T 428/31518 Next to glass or quartz
• CPC Class Codes: Y10T 428/31522 Next to metal

Abstract

A circuit board with insulated wire thereon is encapsulated with a photocurable adhesive composition comprising a phenoxy resin; a reaction product of an unsaturated carboxylic acid and epoxidized non-linear novolak; reaction product of an unsaturated carboxylic acid and a tetrabrominated diglycidyl ether of a phenol; monohydroxy dipentaerythritol acrylate and/or pentaerythritol tetraacrylate; polyethylenically unsaturated compound; and photoinitiator, and optionally, hexamethylol melamine-formaldehyde; and/or a thixotropic agent.

Claims

1. An encapsulated wire circuit board comprising a rigid base plane;

a layer of glass epoxy prepreg covering said base plane;

a layer of photocured adhesive covering said epoxy prepreg, said adhesive comprising;

A) about 21% to about 32% phenoxy resin;

B) about 7.5% to about 17.5% by weight of reaction product of monoethylenically unsaturated carboxylic acid and an epoxy polymer being an epoxidized non-linear novolak having at least six terminal epoxy groups, wherein the relative amount of said acid to said epoxy polymer is sufficient to react stoichiometrically with about 80% to about 100% of the epoxide functionality of said epoxy polymer;

C) about 30% to about 36% by weight of reaction product of tetrabrominated diglycidyl ether of a phenol and monoethylenically unsaturated carboxylic acid, wherein the relative amount of said acid to said ether is sufficient to react stoichiometrically with about 80% to about 100% of the epoxide functionality of said epoxy polymer;

D) about 9% to about 19.5% by weight of monohydroxy-dipentaerythritol pentaacrylate, or pentaerythritol tetracrylate, or mixtures thereof;

E) about 3.5% to about 14% by weight of polyethylenically unsaturated compound selected from the group consisting of diacrylates of diols, dimethacrylates of diols, triacrylates of triols, trimethacrylates of triols, methylene bisacrylamide, methylene bismethacrylamide, divinyl succinate;

divinyl adipate;

divinyl phthalate, divinyl terephthalate, and the reaction product of sorbaldehyde reacted with hydroxy groups present on phenoxy polymer;

F) up to about 6.5% by weight of hexamethyoxymethyl melamine;

G) about 1% to about 6.5% by weight of photoinitiator; and

H) up to about 10% by weight of a thixotropic agent; and

insulated wires encapsulated in said adhesive.

2. The board of claim 1 wherein the amount of A) is about 26% to about 27% by weight;

B) is about 12% to about 13% by weight;

C) is about 30% to about 31% by weight;

D) is about 14% to about 15% by weight;

E) is about 8% to about 9% by weight;

F) is about 1% to about 2% by weight;

G) is about 1% to about 2% by weight; and

H) is about 4% to about 6% by weight.

3. The board of claim 1 wherein said epoxidized non-linear novolak has the average formula:

##STR8##

4. The board of claim 3 wherein said tetrabrominated diglycidyl ether is of bisphenol A and has an epoxy equivalent of about 200 to about 220;

D) is monohydroxy-dipentaerythritol dentaacrylate;

said polyethylenically unsaturated compound is trimethylol propane triacrylate;

said photoinitiator is 2,2-dimethoxy-2-phenyl acetophenone; and

said thixotropic agent is colloidal silica.

5. The board of claim 4 wherein the amount of A) is about 26% to about 27% by weight;

B) is about 12% to about 13% by weight;

C) is about 30% to about 31% by weight;

D) is about 14% to about 15% by weight;

E) is about 8% to about 9% by weight;

F) is about 1% to about 2% by weight;

G) is about 1% to about 2% by weight; and

H) is about 4% to about 6% by weight.

6. The board of claim 1 wherein said tetrabrominated diglycidyl ether is of bisphenol A and has an epoxy equivalent of about 200 to about 220.

7. The board of claim 1 wherein D) is monohydroxydipentaerythritol pentaacrylate.

8. The board of claim 1 wherein said polyethylenically unsaturated compound is trimethylolpropane triacrylate.

9. The board of claim 1 wherein said photoinitiator is 2,2-dimethoxy-2-phenyl acetophenol.

10. The board of claim 1 wherein said thixotropic agent is colloidal silica.

11. The board of claim 1 wherein said polyethylenically unsaturated compound is selected from the group consisting of ethylene diacrylate;

diethylene glycol diacrylate;

glycerol diacrylate;

glycerol triacrylate;

ethylene dimethacrylate;

1,3-propylene dimethacrylate;

1,2,4-butene triol trimethacrylate;

1,4-benzenediol dimethacrylate;

1,3-propane diol diacrylate;

1,6-hexane diol diacrylate;

the bis-acrylates and methacrylates of polyethylene glycols of molecular weight 200-500;

trimethylol propane triacrylate;

methylene bisacryl and bismethacrylamide;

divinyl succinate;

divinyl adipate;

divinyl phthalate, divinyl terephthalate, and the reaction product of sorbaldehyde with hydroxyl groups present on phenoxy polymer.