| 摘要 |
PROBLEM TO BE SOLVED: To prevent air remaining in a non-through hole and through hole by submerging a substrate comprising non-through hole or/and through hole in a liquid where dissolved oxygen has been removed, and applying an ultrasonic wave vibration to the liquid before an aqueous process is performed. SOLUTION: A dissolved-oxygen-removed water 2 with dissolved oxygen amount 5 ppm or below which is heated to 30-50 deg.C is put in a dissolved oxygen processing bath 1. Every time a substrate 4 is processed, the dissolved oxygen in water is occasionally processed with a removing device 6. An ultrasonic wave generating device 3 is provided on the bottom of it which generates an ultrasonic wave of 30-40 kHz at output of 500-700 w for 3-10 minutes. Thus, no air remains in minute non-through hole or small-diameter through hole which are opened by laser machining or drilling in various aqueous process such as desmear process or plating process.
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