Enhanced Polymer Passivation Layer for Wafer Level Chip Scale ...
Enhanced Polymer Passivation Layer for Wafer Level Chip Scale ...
Enhanced Polymer Passivation Layer for Wafer Level Chip Scale ...
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6. Post-UV exposure bake: This step was accomplished at 100 o C <strong>for</strong> 5min on a hotplate to<br />
cure and crosslink the material right after the exposure. Without this step, the resin will<br />
not cure all the way, which will lead to the bad development result. Since the photo<br />
initiator of the SolderBrace material is thermally unstable, the processing conditions are<br />
critical. There<strong>for</strong>e, a thermocouple was attached to the sample to make sure the hotplate<br />
was at the proper temperature. +/- 5 o C would not change the cure, but a 10-15 o C change<br />
might, and the drying procedure in particular is sensitive to large changes in temperature.<br />
Too hot and the film will have more internal stress and cracks while too cool and the film<br />
remains tacky.<br />
Figure 3.8 Pattern <strong>for</strong> SolderBrace coating<br />
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