US 5,206,705 AGranted

Method of checking external shape of solder portion

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorNobufumi Tokura

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Abstract

The upper-limit height of a solder portion based on the thickness of a lead or a chip is set, and the maximum height of the solder portion measured with a laser beam is compared with the set upper-limit height, thereby to judge the acceptance or rejection of the shape of the solder portion. In addition, the lower-limit height of a solder portion based on the thickness of a lead or a chip is set, and the maximum height of the solder portion measured with a laser beam is compared with the set lower-limit height, thereby to judge the acceptance or rejection of the shape of the solder portion. Besides, the lower-limit wetting angle of a solder fillet is set, and the wetting angle of the solder fillet measured with a laser beam is compared with the set lower-limit wetting angle, thereby to judge the acceptance or rejection of the shape of the solder fillet.

Claims1

Dependent claims

A method of checking an external shape of a solder portion of a chip which includes a mold member, a lead and said solder portion, the solder portion bonding said chip to a circuit board, comprising the steps of:

(a) establishing a starting point at an upper surface of the mold member of said chip;
(b) sweepingly projecting a laser beam from said starting point to said solder portion;
(c) employing a position sensor to detect light reflected from said chip and said solder portion in order to measure an external shape of said chip and to detect a location of a reference part of the chip having a height at a predetermined ratio to a height of an upper surface of said molder member;
(d) establishing an offset position which is offset by a predetermined distance from said location of said reference part toward the solder portion;
and
(e) sweepingly projecting the laser beam from said offset position toward an outer end of said solder portion in order to measure an external shape of said solder portion.

3 more elements

Dependencies are inferred from the claim text.