Browse Prior Art Database

Substituting FULLY CURED DIELECTRIC for PREPREG at the COMPOSITE Lamination Level

IP.com Disclosure Number: IPCOM000036775D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Bhatt, AC: AUTHOR [+4]

Abstract

Disclosed is a method of building internal plane printed circuit boards that eliminates up to 85% of the dimensional instability that happens in the composite lamination process.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 70% of the total text.

Page 1 of 2

Substituting FULLY CURED DIELECTRIC for PREPREG at the COMPOSITE Lamination Level

Disclosed is a method of building internal plane printed circuit boards that eliminates up to 85% of the dimensional instability that happens in the composite lamination process.

Manufacture of internal plane circuit boards (composites) begins with core blanks. They consist of dielectric encased between copper layers. Core blanks are circuitized in commonly known lithographic and copper etching or additive copper processes. Both provide desired circuitry.

Multi-layer composites are made using one or more of the circuitized cores. The cores are stacked with prepreg between them and also between them and external copper layers (Fig. 1). Prepreg is a partially cured (B-staged) glass- resin sheet that will become liquid and flow during the composite lamination process. A large part of the instability at this process is caused by the prepreg.

Substitution of fully cured dielectric layers in place of the composite prepreg (Fig. 2) eliminates up to 85% of the movement. The dielectric layers have an adhesive applied to bond them to adjacent cores and copper. Adhesive need not be restricted to the resin used in prepreg. Adhesive is normally in the range of
0.002 inch thick. This is governed by the need for fill in power and signal planes.

The end result is greatly improved laminate stability that provides better registration yields. It also gives more product design latitude.

An additional p...