This is just an Excerpt from a larger document, click here to view the entire document. Summary and Conclusions

The EME-U series mold compound incorporated a red phosphorus flame retardant. Red phosphorus is very reactive, and when exposed to moisture and oxygen, it tends to oxidize and form phosphorus-containing ions and acids which are corrosive to electronics interconnects. To stabilize and insulate the red phosphorus, a coating was applied, which consisted of aluminum hydroxide and phenol resin. Before the launch of these mold compounds, some evaluation tests had been conducted and showed positive results. However, the testing may not have been adequate because failures still occurred in field use.

We identified the root cause of this problem as insufficient coating of the red phosphorus flame retardant particles. It was shown that the red phosphorus content was not completely contained in the particle coating. In addition, the coating can degrade due to the thermal decomposition of the aluminum hydroxide content during manufacture processes. The insufficient coating can lead to the formation of phosphoric ions and acids, which can serve as electrolyte and cause electrochemical migration of the lead material. The migrated lead material forms an unwanted conductive path and can cause a resistive short and leakage current failure.

Sumitomo Bakelite terminated the production of the EME-U series mold compound with red phosphorus flame retardant. The final shipment to Amkor Technology was scheduled in February 2002 [35]. Sumitomo Bakelite released a product change notice [36] in August 2001, which stated Sumitomo Bakelite would change away from the red phosphorus flame retardant.