Claims
- 1. In a method of manufacturing a printed wiring boardbase material consisting essentially of a multiplicity of layers of woven cloth impregnated with a thermosetting polymeric resin varnish and optionally including one or more internal conductive pattern layers, the improvement for providing a base material matched to a copper deposition solution to be used in the manufacture of the printed wiring comprising:
- a. depositing a sample of said copper from the deposition solution, the sample having substantially uniform thickness, and being at least as thick as copper deposits to be used in the manufacture of the printed wiring board;
- b. preparing test specimens from the sample, marking a gauge length on the test specimen, placing the test specimen in a tensile testing machine, applying a strain at a uniform rate until the test specimen breaks, and determining the percent elongation of the specimen at fracture;
- c. determining the sum of the percent elongation at fracture and the coefficient of thermal expansion of copper from 30.degree. C. to 270.degree. C.;
- d. providing the thermosetting resin varnish with an inorganic filler in an amount which is sufficient to provide the base material with an average coefficient of thermal expansion along its Z-axis between 30.degree. C. and 270.degree. C. which is equal to or less than the sum of the percent elongation and the thermal expansion of copper;
- e. forming prepregs by impregnating the woven cloth with the varnish; and
- f. forming said base material by laminating the multiplicity of prepregs together.
- 2. A method according to claim 1 wherein the filler is present in an amount between 30 and 100 parts per hundred parts of the polymeric resin.
- 3. A method according to claim 1 wherein the filler is present in an amount sufficient to provide a surface area of filler in the base material between 150 and 500 sq. meters/100 grams of polymeric resin and filler.
- 4. A method of manufacturing a base material said base material being suitable for printed wiring board manufacture, the method comprising the steps of:
- providing a copper deposition solution and forming a sample copper deposit 35-50 micrometers thick from the solution;
- determining the percent elongation of the sample copper deposit and the average coefficient of thermal expansion from 30.degree. C. to 270.degree. C. of said copper;
- preparing a woven cloth impregnated with a thermosetting resin varnish, the varnish containing an inorganic filler which is present in an amount sufficient to provide the base material with said average coefficient of thermal expansion plus the maximum elongation at 270.degree. C. of said copper deposit; and
- laminating a multiplicity of layers of the impregnated cloth together to form said base material.
- 5. A method according to claim 4 wherein the filler is present in an amount between 30 and 100 parts per hundred parts of the polymeric resin.
- 6. A method according to claim 4 wherein the filler is present in an amount sufficient to provide a surface area of filler in the base material between 150 and 500 sq. meters/100 grams of polymeric resin and filler.
- 7. A method according to claim 5 where the filler is selected from the group consisting of calcium silicate, zirconium silicate and kaolin.
- 8. In a method of manufacturing a printed wiring board having at least one plated-through hole, the improvement comprising:
- a) determining the strain to the elastic limit of the copper to be deposited in the plated-through hole;
- b) providing a base material for the printed wiring board, the base material including a polymeric resin, a fibrous reinforcement, and a filler for the polymeric resin, the polymeric resin having a thermal expansion from 20.degree. C. to 300.degree. C. greater than the thermal expansion of said copper, the filler having a thermal expansion from 20.degree. C. to 300.degree. C. less than the thermal expansion of said copper, and the filler being present in an amount sufficient to reduce the thermal expansion of the base material in the direction of the cylindrical axis of the plated-through hole to less than the sum of the thermal expansion of said copper between 20.degree. C. and 300.degree. C. and strain of the copper deposit to the elastic limit; the printed wiring boards being resistant to failure by thermal stress and thermal cycling.
- 9. A method according to claim 8 wherein the filler is present in an amount between 25 and 100 parts per hundred parts of the polymeric resin.
- 10. A method according to claim 8 wherein the filler is present in an amount sufficient to provide a surface area of filler in the base material between 150 and 500 meters.sup.2 /100 grams of polymeric resin and filler.
- 11. A method according to claim 1 wherein the filler is present in an amount sufficient to provide the base material with an average coefficient of thermal expansion along its Z-axis from 30.degree. C. to 270.degree. C. less than 140.times.10.sup.-6 /.degree.C.
- 12. A method according to claim 4 wherein the filler is present in an amount sufficient to provide the base material with an average coefficient of thermal expansion along its Z-axis from 30.degree. C. to 270.degree. C. less than 140.times.10.sup.-6 /.degree.C.
- 13. A method according to claim 8 wherein the filler is present in an amount sufficient to provide the base material with an average coefficient of thermal expansion along its Z-axis from 30.degree. C. to 270.degree. C. less than 140.times.10.sup.-6 /.degree.C.
Parent Case Info
This application is a continuation-in-part of U.S. patent application Ser. No. 07/534,959 filed Jun. 8, 1990 now abandoned.
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Continuation in Parts (1)
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Number |
Date |
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Parent |
534959 |
Jun 1990 |
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