\0 TO: I4235700 IBMMAIL new address for ipc technet 25.6.96 CROMONT EXFR01 Christian Romont - Exacta France (SARL) FROM: DSTEWART EX2 D.Stewart - Product Development Manager. DATE: 10 September 1997 SUBJECT: BGA and ENAu REFERENCE: phosphorus content Does anyone have any data on the way in which the phosphorus content changes a) during the life of the nickel bath b) as the thickness of the electroless nickel increases ie. is there a gradient in the Phosphorus content from the copper to the gold interfaces. and is this the reason why too little nickel causes solderability problems? The question is asked in conjunction with failures in intermetallic phases when BGAs soldered to ENAu are subjected to vibration and drop testing. Thankyou Dougal Stewart Viasystems, Selkirk