Patent US2536304A successfully refreshed from Google Patents.
Patent US4690836A successfully refreshed from Google Patents.
US4690836A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of void-free prepreg sheets
Assignee: International Business Machines Corp
•
Filing: 1985-10-23
•
Granted: 1987-09-01
•
Expires: 2005-10-23
Abstract
Abstract A method is disclosed for the manufacture of void-free prepregs formed by the impregnation of a reinforcing cloth (e.g. glass fiber cloth) with a solution of a thermosetting resin (e.g. epoxy resin). In the method, the reinforcing cloth is first prewetted with a liquid medium containing a solvent for the resin which has a viscosity less than that of the solution of thermosetting resin. The prewetted cloth is impregnated with a solution of the resin and then heated to remove the solvent and cure the resin. The prepregs are used in the manufacture of printed circuit boards.
Inventors
- 👤 Thomas C. Clarke
- 👤 Neng H. Lu
- 👤 Yaffa Tomkiewicz
- 👤 Ho M. Tong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:14
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/24; C08J5/241; C08J5/244; C08J2363/00; H; H05; H05K; H05K1/00; H05K1/02; H05K1/03; H05K1/0313; H05K1/0353; H05K1/0366; H05K3/00; H05K3/02; H05K3/022
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
80 words
A method for reducing the void content in a prepreg sheet which is prepared by impregnating a reinforcing cloth with a solvent solution of a thermosetting resin, the method comprising first immersing the cloth in a liquid medium having a viscosity less than the solution of thermosetting resin, then immersing the prewetted cloth in a resin solvent solution to impregnate the cloth with said resin solvent solution and then heating the cloth to remove the solvent and cure the resin.
Claim 2
Independent Claim
80 words
A method for reducing the void content in a prepreg sheet which is prepared by impregnating a reinforcing cloth with a solvent solution of a thermosetting resin, the method comprising first immersing the cloth in a liquid medium having a viscosity less than the solution of thermosetting resin, then immersing the prewetted cloth in a resin solvent solution to impregnate the cloth with said resin solvent solution and then heating the cloth to remove the solvent and cure the resin.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein the thermosetting resin is an epoxy resin.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein the cloth is a glass fiber cloth.
Claim 5
Dependent Claim
16 words
The method of claim 1 wherein a curing catalyst is incorporated in the thermosetting resin solution.
Claim 6
Dependent Claim
30 words
The method of claim 4 wherein the cloth is prewetted with a liquid medium which is a solvent for the resin and which exhibits a high solubility for the catalyst.
Claim 7
Dependent Claim
11 words
The method of claim 2 wherein the solvent is N-methyl pyrrolidone.
Claim 8
Dependent Claim
13 words
The method of claim 2 wherein the solvent is ethylene glycol monomethyl ether.
References Cited (Backward Citations)
US3481763A
Cited
US4076869A
Cited
US3843386A
Cited
US3960803A
Cited
US4341821A
Cited
US4180608A
Cited
US4184004A
Cited
US4348248A
Cited
US4375498A
Cited
US4495017A
Cited
US4350602A
Cited
US4327143A
Cited
US4376804A
Cited
US4550128A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-31 | 1991-03-02 | 1991-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-31 | 1995-03-02 | 1995-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-31 | 1999-03-02 | 1999-09-01 | $7700.00 | Window Closed / Lapsed |