| 摘要 |
PROBLEM TO BE SOLVED: To eliminate smear of a via hole which is formed on an electronic circuit board by laser work, by using a dry process. SOLUTION: Fluid C3 containing liquefied inert gas which is formed by liquefying inert gas is so sprayed under an actual atmospheric pressure P that at least a part of the inert gas is turned into solidified fine particles C4. The fine particles C4 are jetted against an electronic circuit board 1, on which a via hole 2 is formed by boring work with laser beam, and a smear 9 in the via hole 2 is removed. |
