| 摘要 |
PROBLEM TO BE SOLVED: To propose a printed wiring board where bumps of low-fusion-point metal containing no lead can properly be formed. SOLUTION: A field via hole 162 is formed to a hollow depth of <=5μm, so the top surface of the field via hole 162 is nearly flat. Therefore, when opening parts 71a and 71b are filled with high-viscosity Sn/Ag paste 77, a void is prevented from being formed.
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