Barbara,
Are you using tin lead solder to assemble the boards? That's what we use and shelf life, coplanarity, fine pitch (QFNs) led us to standardize on ENIG over IAg. Zero problems with our supplier (Bay Area Circuits) who subcontracts the ENIG plating. ENIG needs to be done by a contractor who does a large volume and knows how to keep the process in spec.
Bob Landman
H&L Instruments,LLC
Sent from my iPhone
On Jun 2, 2011, at 10:22 AM, Barbara Burcham <[log in to unmask]> wrote:
> Thanks everyone for you imput. What a great group of people!
>
> Richard,
> The application will be double sided, fine pitch array components, some
> through hole components and going into a shock environment.
> I will need to connect with the assemblers to check on flux and paste
> compounds. Does this information help? You make an excellent point. Must
> have the total picture. I do not know, yet, how long boards will sit on the
> shelf before moving into assembly, either. I do know that shelf life
> will also impact this decision.
> I do not think that I want to use tin...that hairy growth stuff.
> Barbara
>
>
>
> On Thu, Jun 2, 2011 at 8:01 AM, Stadem, Richard D. <[log in to unmask]>wrote:
>
>> Barbara,
>> What is the application, board type, component types, etc?
>> Immersion silver is my personal favorite, but that is completely
>> irrelevant.
>> You should choose a board finish dependent upon the application of the CCA,
>> whether it has fine-pitch array components, including CSPs, whether it is
>> double-sided with PTH parts or hand-soldered components, the environment the
>> CCA will be used in, the flux type to be used, the alloy that is required,
>> and several other factors that go into the decision. Without complete
>> knowledge of all these factors, it is hard for anyone to answer that
>> question. I can tell you that IAg beats ENIG in cost, but each finish has
>> strengths and weaknesses. Some definitely have more or less than others.
>>
>>
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Barbara Burcham
>> Sent: Wednesday, June 01, 2011 8:17 PM
>> To: [log in to unmask]
>> Subject: [TN] Best Board Finish - beyond gold
>>
>> Hey Y'all,
>> I am looking for a reliable bare board finish that beats the cost of gold.
>> What experience is out there?
>> What would you recommend?
>> Thanks,
>> Barbara Burcham
>> pcb Trace Design
>> [log in to unmask]
>>
>>
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