| 摘要 |
PROBLEM TO BE SOLVED: To provide a flexible circuit board device which prevents the migration from appearing in a solder resist lower portion. SOLUTION: An FPC 1 is composed of an insulation film 2 made of polyimide, etc. an adhesive layer 3 laid on the insulation film 2 surface, a plurality of wirings 4, 4 made from a cupper foil, etc., extending mutually in parallel on the adhesive layer 3 surface, an electroless tin plating layer 5 covering the outer surface of each wiring 4, and a solder resist 6 covering the outsides of the electroless tin plating layer 5 and the adhesive layer 3. The electroless tin plating layer 5 is set to a thickness d of about 0.1-0.2μm. This reduces the production quantity of residual ions (Cu<SP>2+</SP>) on the adhesive layer 3 beneath the solder resist 6. COPYRIGHT: (C)2006,JPO&NCIPI
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