Devices employing flexible substrates and method for making same

• US 4,191,800 A
• Filed: 07/26/1978
• Issued: 03/04/1980
• Est. Priority Date: 05/27/1976
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Holtzman, Kenneth A.
• Primary Examiner(s): Goolkasian, John T.
• Assistant Examiner(s): Gallagher, J. J.
• Application Number:
  US05/928,067
• Time in Patent Office: 587 Days
• Field of Search: 427/386, 156/313, 156/324, 156/309, 156/334, 156/330, 428/414-418, 428/901, 428/921, 428/251, 427/386, 264/236, 106/15 FP, 252/403, 252/405, 260/837 R, 260/248 NS, 260/47 EP, 260/47 EQ, 260/47 EC, 260/45.8 R, 260/45.8 NT, 528/103, 29/625, 174/68.5
• US Class Current: 442/233
• CPC Class Codes: B32B 15/14 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 15/20 comprising aluminium or copper B32B15/016 and B32B15/017 take precedence
• CPC Class Codes: B32B 2038/0076 Curing, vulcanising, cross-linking
• CPC Class Codes: B32B 2260/021 Fibrous or filamentary layer
• CPC Class Codes: B32B 2260/046 Synthetic resin
• CPC Class Codes: B32B 2262/0276 Polyester fibres
• CPC Class Codes: B32B 2262/101 Glass fibres
• CPC Class Codes: B32B 2457/00 Electrical equipment
• CPC Class Codes: H05K 1/0366 reinforced, e.g. by fibres, fabrics H05K1/036 takes precedence
• CPC Class Codes: H05K 1/0373 containing additives, e.g. fillers H05K1/036 takes precedence
• CPC Class Codes: H05K 2201/012 Flame-retardant; Preventing of inflammation
• CPC Class Codes: H05K 2201/0145 Polyester, e.g. polyethylene terephthalate [PET], polyethylene naphthalate [PEN]
• CPC Class Codes: H05K 2201/0278 Polymeric fibers
• CPC Class Codes: H05K 2203/122 Organic non-polymeric compounds, e.g. oil, wax or thiol
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 428/31518 Next to glass or quartz
• CPC Class Codes: Y10T 428/31522 Next to metal
• CPC Class Codes: Y10T 442/3423 Plural metallic films or foils or sheets
• CPC Class Codes: Y10T 442/656 Preformed metallic film or foil or sheet [film or foil or sheet had structural integrity prior to association with the nonwoven fabric]

Abstract

Processes and devices are described which employ flexible substrates made from cloth impregnated with a resin of a particular composition. The flexible substrate is made into double-clad printed wiring substrate for use in double-sided circuits. These substrates exhibit excellent dimensional stability during circuit fabrication and soldering as well as excellent flame retardance and electrical insulation resistance.

Claims

1. A process for the fabrication of electronic circuits with flexible substrates comprising the steps of

a. impregnating a cloth-mat material with an epoxy resin-hardener composition free from solvent,

b. adhering a copper sheet to both sides of the impregnated cloth-mat material to form a double-sided clad flexible substrate,

c. curing the double-sided clad flexible substrate by heating, characterized in that epoxy resin-hardener composition consists essentially of, in parts by weight,

View Dependent Claims (2, 3, 4, 5, 6, 7, 8)

2. The process of claim 1 in which the cure is carried out at a temperature between 165 and 170 degrees for a time between 44 and 52 hours.

3. The process of claim 1 in which the epoxy resin-hardener composition consists essentially of, in parts by weight,

4. The process of claim 1 in which the double-sided cladded flexible substrate is exposed to a temperature of from 70 to 90 degrees C. for 12 to 24 hours prior to curing.

5. The process of claim 1 in which the cloth-mat material is made of polyester.

6. The process of claim 1 in which the cloth-mat material is made of glass fibers.

7. The process of claim 1 in which the antioxidant is 3,5-Di-tert-butyl-4-hydroxyhydrocinnamic acid triester of 1,3,5-tris(2-hydroxyethyl)-s-triazino-2,4,6(1H,3H,5H)-trione.

8. An electronic device with flexible substrate produced according to the process of claim 1.