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

A fabrication process is proposed for thin-film multilayer substrates. The process involves the lamination of polyimide sheets with previously inspected wiring patterns. Several technical points were investigated during development. 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 for forming blind via holes with a high aspect ratio. These holes can be metallized successfully by electroless copper plating.<
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