| 摘要 |
<p>PURPOSE:To make it possible to reduce the curl of polyimide film layer after etching by reducing roughness of copper foil on the varnish adhesion surface in flexible copper clad laminates of two layer type. CONSTITUTION:Copper foil having small roughness, approximately 35mum in thickness, is formed over a stainless steel plate, SUS 304 type, by depositing copper thereto by electric plating. Average surface roughness of the copper foil obtained is 0.2mum on the side of the plate of SU and 0.3mum on the opposite side thereof. Thereafter, polyamide acid varnish is applied to the copper foil to form a layer having a thickness of 25mum after being cured. After coating, the foil is dried in an oven at a temperature of 150 deg.C for 30 minutes and then cured in a nitrogen stream of 400 deg.C. The smaller the roughness of copper foil is, the more advantageous; however, with the roughness of copper foil surface in a range of 0.3-0.8mum, similar curl can be obtained.</p> |
