Ryuji Watanabe

Fabrication of thin-film multilayer substrate using copper clad polyimide sheets

A novel fabrication process is proposed for thin film multilayer substrates. The feature of the process involves the lamination of polyimide sheets with previously inspected wiring patterns. Several technical points were investigated during development of the process. Fairly large dimensional changes occur in the polyimide sheets in the copper etching and lamination steps. However, these changes can be restrained by fixing the sheets to rigid frames. Excimer laser ablation is a useful method to form blind via holes with a high aspect ratio. These holes can be metallized successfully by electroless copper plating. >

Thin film laminated multilayer wiring board for multichip modules

A high density multilayer wiring board was developed, using thin film laminating technology. The fundamental features of the fabrication process are laminating the high heat resistant polymer film with an adhesive layer, forming via holes by plasma etching and filling them up by electroless copper metallization. The heat resistant adhesive layer consists of polyimide as the matrix and bismaleimide as the melting constituent. Heat resistance of more than 10 min. at 330/spl deg/C can be achieved. The via holes of /spl phi/=25 /spl mu/m are formed by a conformal mask method using plasma etching. This paper describes the fundamental technologies for the fabrication process particularly focusing on electroless copper plating.