| 摘要 |
PROBLEM TO BE SOLVED: To form a specified number of solder balls at the bottom of a board without solder balls falling off by forming a solder ball retaining hole in such a taper form that it tapers from the chip mounting face for mounting a semiconductor chip to the ball formation face for forming a solder ball. SOLUTION: A solder ball retaining hole 5 is made in roughly conical form which tapers from a ball formation face 4 to a chip mounting face 3, and a hole electrode 6 is made at the inside periphery. Moreover, a concentric land 15 for wiring is made at the opening 14 of a chip mounting face 3, while a land 16 for bait formation is made at the opening 9 of the ball formation face 4. When screen-printing solder in the opening 9 of the solder ball retaining hole 5, paste-form solder can insert into the interior along the tapered inside peripheral face of the solder ball retaining hole 5, and the inside can be filled with solder, whereby a solder ball 10 can be retained firmly in the opening 9. |
