Most encapsulation adhesives are highly filled systems. In underfill and epoxy molding compounds, large density differences exist between silica fillers, silver powder and resin matrix. Insufficient mixing easily causes local sedimentation or agglomeration. Trapped bubbles inside the adhesive layer will expand into voids after curing and reliability tests, directly lowering packaging yield. Such adhesives are usually processed in small batches with frequent formula changes, which places high requirements on small-volume equipment and process window confirmation. Batch consistency of adhesives becomes a prerequisite for packaging yield.

News released on the evening of October 21: BIWIN Storage plans to invest 4.5 billion yuan of self-raised funds in Phase III of its wafer-level advanced packaging and testing project, scheduled to start production in December 2029. Advanced packaging has become the second growth curve for its memory business. Driven by intensive capacity expansion in memory packaging, the consumption of underfill, epoxy molding compounds and other adhesives keeps rising with production line ramp-up. The same adhesive type needs stable supply for multiple machines while formulas are frequently switched. Packaging houses are paying closer attention to adhesive mixing and defoaming procedures.

Packaging material manufacturers and OSAT plants normally confirm defoaming windows with actual adhesives during material qualification, then transfer the verified process to pilot and mass-production machines. SIENOX engineers have recently received many inquiries from packaging material suppliers and OSAT factories, requesting parallel multi-formula verification on small-volume equipment.

The SIENOX MIX60 used for verification is a lab-scale model for formula evaluation with a 300ml processing capacity suitable for small-batch testing. It adopts a planetary revolution-and-rotation structure. Shear force from rotation plus mixing force from revolution quickly disperse highly filled adhesives and push bubbles to the surface. Bubbles are simultaneously removed under vacuum (-98KPa). The maximum speed reaches 2000rpm, and temperature control is available as a customized option. The small volume enables parallel comparison of multiple formulas, and verified parameters can be seamlessly transferred to pilot and mass-production equipment.

No residual bubbles are left in tested adhesives, with stable viscosity and performance across batches. Amid packaging capacity expansion, epoxy vacuum defoaming mixers for highly filled systems are being added to verification lists by more OSAT factories. The matching performance of silver paste defoaming machines for chip mounting is also gaining attention. The above content is compiled from public industry data; actual test results shall be subject to customer trials.