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Subject:
From:
Gabriela Bogdan <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gabriela Bogdan <[log in to unmask]>
Date:
Tue, 29 Jan 2008 19:49:02 +0200
Content-Type:
text/plain
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text/plain (308 lines)
No, I don't.
Circuits are "fresh".
Gaby
----- Original Message ----- 
From: "Reuven Rokah" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, January 29, 2008 10:53 AM
Subject: Re: [TN] Microvoids immersion silver


Hi Gaby,
May be you are baking the PCBs before the process?
If yes, what is the temp and time?

Oxidation can cause also opens and voids.

Best Regards
Reuven ROKAH
e mail: [log in to unmask]


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gabriela Bogdan
Sent: Tuesday, January 29, 2008 5:29 AM
To: [log in to unmask]
Subject: Re: [TN] Microvoids immersion silver

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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