Development of improved printed wiring board inner layer adhesion
Abstract
Polyimide multilayer printed wiring boards (MLPWB) offer much higher temperature resistance than epoxy MLPWB, however, their usage is limited due to inner layer delamination problems. This study has determined the primary cause of delamination as adhesive failure to inner layer copper surfaces. Copper surfaced treatments based on sodium chlorite when used with a ferric chloride/hydrochloric acid pre-etch were found to eliminate these delamination problems. A test specimen based on ASTM D2733 was developed for measuring the inner layer adhesion of MLPWB. Also evaluated was a floating roller technique for measuring the peel strength of copper foil. This technique gave consistent, low-chatter peel strength values. Analytical techniques were also developed for characterizing polyimide prepregs. In general, the polyimide prepregs are of high quality and excellent consistency. MLPWB's fabricated to those materials and processes optimized per this study exhibited excellent moisture and thermal resistances when tested per applicable military specifications.
- Publication:
-
Final Report
- Pub Date:
- June 1982
- Bibcode:
- 1982racy.rept.....B
- Keywords:
-
- Adhesion;
- Adhesives;
- Failure;
- Layers;
- Printed Circuits;
- Thermal Resistance;
- Applications Of Mathematics;
- Polyimide Resins;
- Reinforced Plastics;
- Shear Strength;
- Structural Analysis;
- Surface Properties;
- Electronics and Electrical Engineering