| 摘要 |
PROBLEM TO BE SOLVED: To facilitate partial plating to a printed wiring board, on which an IC is mounted through facedown bonding. SOLUTION: On a printed wiring board 14 of a portable telephone set 11, CSP ICs are mounted, and a key matrix 50 of 4 rows by 3 columns is constituted for detecting on/off of an operation key with a contact part 18. By using wiring patterns 19a-19c and 20a-20d which constitute the key matrix 50, partial electroplating is performed, and the contact part 18 of 12 portions is subjected to nickel-gold plating.
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