| 摘要 |
Solder paste is applied beforehand onto through-hole upper lands (or solder) of a printed circuit board and attachment is effected by inserting solder joined to the BGA-side pads into the holes of the through-hole upper lands; solder and solder paste are then melted by heating, causing them to flow into the through-holes and to wet and spread out upon the through-hole bottom face lands, thereby effecting a soldered joint with the BGA-side pads and through-hole upper lands securely attached, and forming solder fillets. In this way, the quality of the solder joints can be ascertained by an ordinary external inspection method.
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