Sheet material impregnated with a highly cross linked thermally stable epoxy composition

• US 4,452,847 A
• Filed: 11/17/1982
• Issued: 06/05/1984
• Est. Priority Date: 11/17/1982
• Status: Expired due to Term

• Current Assignee: Isola Laminate Systems Corp. (TPG Hattrick Holdco LLC)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Siemon, John T.
• Primary Examiner(s): Bell, James J.
• Application Number:
  US06/442,479
• Time in Patent Office: 566 Days
• Field of Search: 428/251, 428/268, 428/273, 428/413, 428/414, 428/415, 428/417, 428/901, 428/246, 428/920, 174/68.5, 361/414
• US Class Current: 442/149
• CPC Class Codes: B32B 15/14 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 2260/021 Fibrous or filamentary layer layers of natural mineral fibres or particles being impregnated in a plastic substance B32B19/02
• CPC Class Codes: B32B 2260/046 Synthetic resin
• CPC Class Codes: B32B 2307/3065 Flame resistant or retardant, fire resistant or retardant
• CPC Class Codes: B32B 2309/105 Thickness
• CPC Class Codes: B32B 2315/085 Glass fiber cloth or fabric
• CPC Class Codes: B32B 2457/08 PCBs, i.e. printed circuit boards
• CPC Class Codes: B32B 27/04 as impregnant, bonding, or embedding substance not used
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C08G 59/4021 Ureas; Thioureas; Guanidines; Dicyandiamides
• CPC Class Codes: C08G 59/686 containing nitrogen
• CPC Class Codes: C08J 2363/00 Characterised by the use of epoxy resins; Derivatives of epoxy resins
• CPC Class Codes: C08J 5/244 using glass fibres
• CPC Class Codes: C08J 5/249 characterised by the additives used in the prepolymer mixture
• CPC Class Codes: H05K 1/0326 containing O
• CPC Class Codes: H05K 3/4626 characterised by the insulating layers or materials H05K3/4688 takes precedence
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10S 428/92 Fire or heat protection feature
• CPC Class Codes: Y10T 428/31511 Of epoxy ether
• CPC Class Codes: Y10T 428/31518 Next to glass or quartz
• CPC Class Codes: Y10T 428/31525 : Next to glass or quartz
• CPC Class Codes: Y10T 442/2721 : Nitrogen containing
• CPC Class Codes: Y10T 442/2738 : Coating or impregnation intended to function as an adhesive to solid surfaces subsequently associated therewith
• CPC Class Codes: Y10T 442/3415 : Preformed metallic film or foil or sheet [film or foil or sheet had structural integrity prior to association with the woven fabric]

Abstract

An alkyl-di-substituted imidazole, is used as accelerator and co-curing agent in epoxy coating and impregnating resins useful in the manufacture of high temperature multi-layer laminates.

Claims

1. A "B"-staged adhesive resin impregnated material comprising glass fabric, the resin comprising:

(A) epoxy resin;

(B) curing agent selected from the group consisting of dicyandiamide, monomethylol dicyandiamide, and mixtures thereof; and

(C) accelerator, co-curing agent consisting of 2-alkyl, 4-methylimidazole having the structural formula;

##STR2## where the alkyl group R contains from 2 to 8 carbon atoms, where the weight ratio of (epoxy);

(curing agent);

(2-alkyl, 4-methylimidazole) is from about (100);

(2.0 to 2.5);

(0.5 to 1.0), said impregnated material characterized as having a Tg (DSC) value of over about 150°

C. upon complete cure.

2. The resin impregnated material of claim 1 being glass fabric;

and wherein the epoxy resin is a diglycidyl ether of bisphenol A, the impregnated material is characterized as being thermally stable, and having low expansion properties upon complete cure, and the resin has a fast, "B"-stage gel time.

3. The resin impregnated material of claim 1, also containing an effective amount of flame retardant and an effective amount of diluent for the flame retardant and the curing agent.

4. The resin impregnated material of claim 1, wherein the 2-alkyl, 4-methylimidazole is 2-ethyl, 4-methylimidazole.

5. A laminated multilayer printed circuit board comprising at least two circuit boards, each circuit board comprising at least one metal conductor sheet supported by a core laminate, with an adhesive separator disposed between at least two circuit boards in the multilayer board, the adhesive separator being the cured resin impregnated material of claim 1.

6. The multilayer printed circuit board of claim 5, wherein the metal conductor sheet is a patterned copper electrical circuit and the resin impregnated material in the adhesive separator is glass fabric.