Yes, I know, it is our preferred coating also, just had by bad luck two
batches from two different suppliers with excessive microvoids, that's what
made me start the discussion.
Thank you all,
Gaby
----- Original Message -----
From: "Lee parker" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, January 28, 2008 10:14 PM
Subject: Re: [TN] Microvoids immersion silver
> Gaby
>
> There is no reason to suspect that soldering issues of any kind will be
> aggravated by immersion silver provided the chemistry is up to par, the
> process is within the bath supplier's spec and there is an adequate
> quality control process in place. Immersion silver has been widely used by
> many OEMs with great success, AT&T, Andrew etc. Immersion sliver voids
> have been reported by some suppliers, but most of these issues were
> resolved by the MacDermid study, I imagine Danny Fritz can get you a copy
> of the paper. I installed this process in the AT&T Richmond Works in 95. I
> have not heard of any soldering issues that were not quickly resolved,
> certainly nothing on the order of black pad.
>
> I would certainly qualify any potential supplier to verify the process
> meets the vendor's spec and that a quality control plan is in place and on
> going. I would also monitor the quality of the silver coating (thickness
> measurements, cross sections and solderability assessments etc.) If the
> quality of the coating is robust over a extended period of time, I would
> then begin to expand the inspection interval.
>
> To insure a quality product from all stand points it is absolutely
> necessary to continuously monitor the supplier with on site visits whether
> the supplier is on shore or off shore. This of course is one of the
> disadvantages of off shore suppliers.
>
> Best regards
>
> Lee
>
> J. Lee Parker, Ph.D.
> JLP Consultants LLC
> 804 779 3389
>
>
> ----- Original Message -----
> From: "Gabriela Bogdan" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, January 28, 2008 1:30 PM
> Subject: Re: [TN] Microvoids immersion silver
>
>
>> Thank you all for your information.
>> Now, next:
>> Opens in BGA on Immersion silver.
>> MICROvoids detected by X-ray on : free pads, ordinary smt joints, BGA
>> solder
>> joints (ball to circuit pad location).
>> BGA rework?
>> BGA replacement?
>> SCRAP??????
>> I fear that the story begins to be similar to the black pad nightmare
>> with
>> immersion gold.....
>> Gaby
>> ----- Original Message -----
>> From: "Dennis Fritz" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Monday, January 28, 2008 8:17 PM
>> Subject: Re: [TN] Microvoids immersion silver
>>
>>
>> >I will try to answer each question as you ask them.
>> >
>> > In a message dated 1/28/2008 12:32:15 P.M. Eastern Standard Time,
>> > [log in to unmask] writes:
>> >
>> > Dear Netters,
>> > Is there a preferred process for immersion silver finish in order to
>> > minimize microvoids?
>> > Immersion silver vendors have a preferred way for fabricators to
>> > operate
>> > the
>> > immersion silver line to minimize/prevent microvoids. Please
>> > understand
>> > there are more effects than just the immersion silver bath itself.
>> >
>> >
>> > How do you choose the preferred immersion silver PCB supplier?
>> > Your board supplier is very interactive in the performance of immersion
>> > silver boards. The best plating solution, run poorly by a fabricator
>> > can
>> > give
>> > problems and vice versa. Obtain boards from more than one fabricator
>> > and
>> > from
>> > various bath suppliers. Probably, the bath vendor has an opinion,
>> > from
>> > process audits, how each fabricator is obeying the process information
>> > in
>> > the data
>> > sheets. See what works best with your solder paste and wave solder.
>> > Wetting balance, dip-and-look, solder spread are all tests that
>> > indicate
>> > good
>> > performance.
>> >
>> >
>> > Which test for bare boards could give the best information?
>> > IPC J-standard 003 for board solderability should be a guide for your
>> > operation. Do you use international IEC standards?
>> >
>> >
>> > Should I perform a print and reflow test for each batch, followed by
>> > x-ray?
>> > The print/reflow test is a good idea, with controlled conditions.
>> > However,
>> > I
>> > don't think you will see microvoids with X-ray. You probably need
>> > cross
>> > sectioning to see microvoids.
>> >
>> >
>> > Which tests are the suppliers performing?
>> > By suppliers, do you mean board fabricators or plating chemistry
>> > suppliers?
>> > This is not a one stop shop. The board shop should be running process
>> > controls on their microetch for roughness and silver immersion plating
>> > bath. The
>> > plating rate and final thickness are recommended by the bath supplier,
>> > and
>> > should be obeyed in fabrication. Both shop and supplier may be running
>> > assembly
>> > simulation and then cross sectioning to see if there are any
>> > microvoids.
>> >
>> >
>> > Thanks,
>> > Gaby
>> >
>> > Dennis Fritz
>> > MacDermid, Inc.
>> >
>> >
>> >
>> > **************Start the year off right. Easy ways to stay in shape.
>> > http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489
>> >
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