| 摘要 |
PURPOSE: To provide a brazing rejection covering by providing brazing rejection varnish on the entire surface of a printed circuit board, overlapping a positive photoresist on the entire surface, and performing selectively exposure and development in the range of through-hole and/or brazing pad. CONSTITUTION: After a brazing rejection varnish 5 has been provided for a printed circuit board with a conductor path 2, a through-hole 3, and a brazing pad 4 on an electrically insulated substrate 1, a positive photoresist is provided on an entire surface. Exposure is made by the scanning method using a laser and light is applied obliquely to a hole wall. A range 60 of a photoresist 6 being exposed is eliminated. After a development has been completed, the exposure range of the brazing rejection varnish 5 is peeled off. Then, the remaining photoresist 6 is eliminated, and then the remaining range of the brazing rejection varnish 5 is thermally cured. After that, the through-hole 3 and the brazing pad 4 are selectively covered with tin/lead alloy without problems in succession by a high-temperature tin-plating method. |
