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The reduction in size and thickness of dice for new packages makes them susceptible to die cracking. In this study, TSSOP die cracking defects due to front-of-line processes were investigated. Three root causes were eventually identified: long blade exposure and expired uV wafer tape at wafer saw, and incorrect ejector needle diameter at die bond. Long blade exposure and expired uV wafer tapes can result in blade dents, which in turn can produce die cracking and backside chipping. On the other hand, the use of improper ejector needle tip diameter and excessive pick-up parameters can cause ejector needle marks on the die backside, which can aggravate into die cracks. To address these problems, the wafer blade exposure selection was improved, this time taking into account the wafer thickness. A switch from uV wafer tape to the standard wafer tape was also done, eliminating the tape expiration issue. The use of a less damaging needle tip diameter was likewise standardized (in this study, 100-micron tips became the standard), while the die pick-up parameters were optimized.
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