Field failures?

Maxim has reported potential degradation problems in ICs that have used a Japanese phosphorus-based moulding compound.

The Sumitomo EMExxxxU Series of phosphorus-based moulding compound was introduced to the industry in approximately 1996. Phosphorus particles were reportedly included as a flame retardant replacing Bromine and Antimony in response to popular political pressure to create a more ‘environmentally-friendly ‘ material for use in semiconductor products.

According to Maxim, the moulding compound was incorporated by subcontractor assemblers without full knowledge of the impact of the phosphorus material. The change appears to have created potential degradation in products manufactured industry-wide by subcontractor assemblers who used the Sumitomo EMExxxxU Series moulding compound.

The particular moulding compound has become associated with failures in products across the industry in which silver dendrite growth forms between adjacent pins and results in high resistance shorts between the pins. Unfortunately, millions of units were shipped by the industry containing the Sumitomo EMExxxxU Series moulding compound before the problem was identified.

Maxim stresses in the document that it is giving the advisement out of caution. Maxim has not been able to reproduce this failure mechanism and Maxim understands from Sumitomo that there has been no conclusive determination that the Sumitomo EMExxxxU Series moulding compound is the direct cause of this failure mechanism.

Circumstantial evidence, however, does suggest that there is a causal relationship, and that the change to a different moulding compound has avoided this failure mechanism. Upon learning of the silver dendrite failure mechanism, Maxim contacted its subcontractor assembler, Amkor Technology and Sumitomo Plastics America, the US representative of Sumitomo Bakelite, the manufacturer of the EMExxxxU Series moulding compound.

Maxim was advised that Sumitomo had already been working on changes to the moulding compound to correct this condition. Sumitomo then issued a Product Change Notification (PCN) to their direct customers, the subcontract assemblers. While the changes Sumitomo made to the moulding compound appear to have resolved the problem, Sumitomo apparently already had plans to stop manufacturing the moulding compound at the time Maxim learned of the silver dendrite failure mechanism.

Maxim was among the first companies in the industry to demand that subcontract assemblers stop using the Sumitomo EMExxxxU Series moulding compound in product assembly, even though there was no direct evidence of the causal relationship.

Maxim has identified one standard product that was assembled by subcontractors using the Sumitomo EMExxxxU Series moulding compound that has exhibited failures: The MAX2104 sold by LSI as the L64733.

Maxim manufactured the MAX2104 exclusively for LSI from November 1999 to July 2001. During this time, the product was co-branded as the LSI L64733. The MAX2104/L64733 product with date codes preceding 0145 contains the Sumitomo EMExxxxU Series moulding compound.

There have been no reported failures of MAX2104 product sold directly by Maxim. Between July and November 2001, MAX2104 product sold directly by Maxim (Date Codes 0126 to 0144) contained a phosphorous-based moulding compound that was modified by Sumitomo without Maxim ‘s knowledge.

This modified version appears to have reduced the potential for problems, as there have been no reported failures within this time period. MAX2104 product sold after November 21,2001, (Date Codes 0145 and later) was manufactured with non-phosphorus moulding compound and has had no reported failures.