| 摘要 |
PROBLEM TO BE SOLVED: To improve the heat resistance property of a junction metal by using tin plating with copper ground as the junction metal of a via for electrically connecting a plurality of adjacent circuit boards and forming a tin/copper alloy for electrical connection. SOLUTION: A copper foil 102 is affixed to a polyimide film 101 as an insulation layer, a laser beam is applied from the reverse side of the film 101, and a blind via 103 where the surface copper foil 102 becomes a stopper is formed. A copper via 104 is formed so that a salient electrode can be formed by filling plating copper into the via 103. After that, a protective film 106 is affixed to the reverse side of the film 101, and a photolithographic process is made, thus allowing a resist 107 to remain at a required part. With the resist 107 as a mask, unwanted copper is eliminated by etching and a copper foil pattern 108 is formed, then a tin layer is laminated, and further an adhesive film 110 is affixed to the reverse side of the film 101 and is subjected to thermocompression bonding, thus forming a tin/copper alloy for electrical connection. |
