ENIG Finish for BGA Designs

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We received bare PCB's that were supposed to have been finis... - Jul 23, 2004 by

Both imm silver and ENIG provide flat surfaces that are bett... - Jul 26, 2004 by davef

B. Hunter

#29632

ENIG Finish for BGA Designs | 23 July, 2004

We received bare PCB's that were supposed to have been finished with immersion silver because of BGA locations. The boards were finished in ENIG.

We are concerned over any reliabilty problems that might occur as a result of using ENIG at BGA locations. Any comments would be helpful.

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davef

#29655

ENIG Finish for BGA Designs | 26 July, 2004

Both imm silver and ENIG provide flat surfaces that are better for fine pitch placement and reflow than HASL.

We know of nothing that makes BGA locations different than other locations when using ENIG solderability protection. More broadly, the primary concern about ENIG reliability has to do with hyper-corrosion of the nickel surface, commonly referred to as "black pad", that makes the pads unsolderable. [Search the fine SMTnet Archives for background on black pad.]

If your supplier can convince you that these boards are solderable and that they have had no "black pad" problems in the past, then consider accepting the boards.

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