| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for removing a connection defect due to the relation between diameters of a through-hole of a substrate and a solder ball with respect to a BGA package having the solder ball connected directly to the through-hole of the substrate. <P>SOLUTION: Denoting the diameter of the solder ball 20 as A and the diameter of the through-hole 18 as B, a relation of A/B<1.25 is satisfied and the force of the solder ball 20 to become spherical never exceeds the bonding force between the solder ball 20 and a wiring pattern 16. The relation of A/B<1.25 is determined through experiment as a condition wherein the ball does not fall. Consequently, the ball is prevented from falling to greatly lower the occurrence rate of a mounting defect. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
