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The problem of backside cracking encountered during 100% saw-through on Au-back wafers with small die sizes (15x15 to 30x30 mils) was addressed in this study. The dice from these wafers are intended for eutectic die attach. A designed experiment and statistical analysis showed that of the 8 factors studied, the type of blade used has the biggest effect on backside cracks. To eliminate the backside cracking issue, the interaction effect of blade type and cutting speed was
optimized. The backside cracks were successfully eliminated using the following combination of factors: a blade thickness of 0.8 to 1-mil, exposure of 25-30 mils, diamond grit size of 2-4 microns, and a cut speed of 40 mm/sec. The use of variable search and full factorial experimental designs led to immediate and effective resolution of the problem.
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