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SMT electronics assembly manufacturing forum.


ENIG finishing

#1946

ENIG finishing | 11 February, 2000

We're considering an ENIG finish on some of our boards to resolve some coplanarity concerns with 20 mil pitch QFP100s.

I welcome any comments on the subject, especially regarding solderability and the variables of ENIG that affect it, but would particularly like to hear comments re: the following link:

http://www.automata.com/capblity/fab/immerau.htm

and the accuracy and/or reliability of the information it conveys.

Also, anyone have any suggestions on a better way to go than ENIG? Plating? OSP? We have shelf life concerns for the latter, but all info. is appreciated regardless. Thanks.

Steve

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JAX

#1947

Re: ENIG finishing | 14 February, 2000

Steve, I have just one question. Do you place any other QFP's that have 20mil pitch or less? Do you see the same problems? You might be able to solve the problem using other methods. If not, will the ENIG finish on the boards be a profitable move. If it is only happening on a specific part, you might get away with having the leads of the part coated (ex. palladium, ect... ) No need reducing the profit margin if you don't have to! Thats just my opinion, I could be wrong!

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#1948

Re: ENIG finishing | 14 February, 2000

Steve: Several points:

* I don't have any real problems with the paper that you referenced. The hair on the back of my neck did rise a bit when the paper touched-on the higher level of process control required for ENIG. * JAX makes a good point. There is no magic bullet out there. You pay for everything. HASL from the correct supplier can be wonderful. * Have you considered a fused HASL surface to get past your planarity issues? (I'd love to get that ol'fart Earl wound on that one, but alas ...) * SMTnet archive might be a good source for additional background

Good luck

Dave F

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#1949

Re: ENIG finishing | 15 February, 2000

Thanks for your responses, gentlemen.

I'm really just looking at options, and frankly, being a novice at this stuff I'm looking for the info. required to make a semi educated decision. You, kind sirs, are my educators. And that probably scares me less than it does you. ;-)

We don't use QFP 100's at this pitch anywhere else, so I don't have another reference point. We do install one other 20mil part on another board, an soic, but don't have these solderability issues. Frankly, coplanarity is just one possibility that we're looking at. Paste, print quality/stencil design, profile, pad layout, and lead finish are all being looked at, or have been. Thanks again.

Steve

P.S. Dave, what is a fused HASL finish? And should I sick moonman on you for that?

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#1950

Re: ENIG finishing | 16 February, 2000

Steve: Fused HASL is a routine HASL coating that has been reflowed, giving it a flatter, less domed surface.

Awww ol' Moonie always liked to set things like "fused HASL" straight, at least from the perspective of ...

Ta

Dave F

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