Quality Improvement by Vacuum Laminating of Complex Multilayer Boards

In the production of multilayer boards with 10 and more single layers it was found that air and gas, entrapped in the cured prepreg resin, caused unacceptable scrap. The amount of scrap was growing with increasing pattern density, scrap signifying each board with one air‐ or gas‐bubble ≥50µm in diameter in one of the different bonding areas. To improve the yield in this area, a laminating process under vacuum conditions was developed. The effect of the different process data on the quality will be shown. Besides the laminating process itself, the kind of vacuum seal is an important item. Laminating under vacuum conditions has led to much higher yields in the production of high density multilayer boards. The process is simple in application and the equipment expense is acceptable. Running costs for the process will be shown in detail.