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June 2011

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Subject:
From:
"Stadem, Richard D." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D.
Date:
Thu, 2 Jun 2011 09:55:33 -0500
Content-Type:
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text/plain (157 lines)
Yes, in retrospect, I agree. You would need to have a print change for the part.
I was only looking at it from the assembly drawing standpoint.
I stand corrected. Gerald was right, the reballing would be a repair, if it was not done with specific documented instruction. I am so used to having the BGAs available in both Sn63 and SAC alloy part numbers, but not having one or the other immediately available.

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]] 
Sent: Thursday, June 02, 2011 9:33 AM
To: TechNet E-Mail Forum; Stadem, Richard D.
Subject: RE: [TN] Re-balling BGAs

Richard, I've got to disagree with your disagreement!

It is not rework because it is not in compliance with the BGA
component's print.  If I buy a Motorola BGA and replace the SAC balls
with Sn63 then there is no way Motorola will recognize it as their part,
it does not match their datasheet any longer since their data sheet says
SAC.

The way to make it drawing "legal" would be to create an intermediate
"altered item" drawing for a modified BGA, or else to have a drawing
note on the CCA drawing that says to modify the part.  Simply having a
drawing note that says the assembly is to be Sn63 only results in a
non-buildable drawing.  At least I wouldn't accept it.  

regards,
 - Graham

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Thursday, June 02, 2011 10:20 AM
To: [log in to unmask]
Subject: Re: [TN] Re-balling BGAs

I'm sorry, but I completely disagree with that logic. Rework is defined
as bringing a component or CCA into full compliance with print
requirements. If I have a BGA with SAC alloy balls, remove the SAC balls
and re-attach Sn63 balls and use that re-balled BGA on a CCA whose print
requires Sn63, then it is rework, not repair.

One does not need to follow the original manufacturing method. That is
completely irrelevant. 

You can rework a CCA (or a component) using hot gas, hot air, laser,
solder iron, selective solder, selective vapor phase soldering, and any
number of other methods.

By your definition, any touchup done with a solder iron on a board that
had been vapor-phase soldered would be considered a repair, and thus
would require approval by the customer. Do you do that?

-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]] 
Sent: Thursday, June 02, 2011 6:08 AM
To: Stadem, Richard D.
Subject: RE: Re-balling BGAs

June 2, 2011

Because re-balling is not the original manufacturing method used by the
part manufacturer and the difference between repair and rework is when
you follow the original manufacturing method (like replacement of a part
soldered on an assembly) it is considered a rework and not a repair.
However, if you are not following the original manufacturing method it
is considered a repair and therefore the process of re-balling is a
repair not a rework.

-----Original Message-----
From: Stadem, Richard D. [mailto:[log in to unmask]] 
Sent: Wednesday, June 01, 2011 5:43 PM
To: TechNet E-Mail Forum; Bogert, Gerald L (Contractor)
Subject: RE: Re-balling BGAs

Why would it be a repair? 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerald Bogert
Sent: Wednesday, June 01, 2011 2:22 PM
To: [log in to unmask]
Subject: [TN] Re-balling BGAs

June 1, 2011

 

Anyone have technical data to support (or not support) re-balling of
BGAs to change from SAC balls to Pb balls???

 

My understanding is that because of the extra heat cycle involved, BGA
manufacturers may not stand behind their part warranty if re-balling is
done.  I also seem to recall a technical poster or paper presented at
IPC several years ago which I believe indicated a reduction in
reliability of the part if it is re-balled.

 

Also seems to me that if one were to re-ball a BGA, this would be a
repair and not a reqork process and as such may require specific
customer approval.


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