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July 2010

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Subject:
From:
Joyce Koo <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Joyce Koo <[log in to unmask]>
Date:
Tue, 20 Jul 2010 15:17:55 -0400
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Once the product and process are qualified, pass the reliability. You should not impost any more.  If the witness sample upon qual showed different solder joints height, you should be concerned.  Check the initial design and realiaibility qual document and on file report and do a assessment (it showed process has been changed, the re qual might be required). 
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----- Original Message -----
From: Hart, Dale L CTR USAF AFMC AFRL/RXSA [mailto:[log in to unmask]]
Sent: Tuesday, July 20, 2010 12:51 PM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [TN] solder joint height

Air Force often uses CCA's as circuit card assemblies, sorry for the confusion.  The type of components are surface mount resistors, capacitor and I believe a SOT with gull wing leads.

My problem is do I suggest their solder joint height isn't sufficient enough to ensure a reliable assembly on an aircraft.

 
dlh
 
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Tuesday, July 20, 2010 11:19 AM
To: [log in to unmask]
Subject: Re: [TN] solder joint height


 Hi Dale,
Do you mean CGA's [column grid arrays]? If not, what do you mean by cca?

 610, Class 3 or otherwise, only addresses quality, not reliability—for that you need to go to IPC-D-279.

While the absence of solder fillets can reduce fatigue life, the presence of fillets, 'robust' or otherwise, does not have any positive first-order impact. However, solder joint height does.


 You may be looking at IMC crystals.
Werner

 

-----Original Message-----
From: Hart, Dale L CTR USAF AFMC AFRL/RXSA <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, Jul 20, 2010 9:23 am
Subject: [TN] solder joint height


 



We have been doing a some analysis of cca's for the Air Force consisting of

SMT.  The visual inspection of the solder joints looks very good all

characteristics above the suggest minimum for class 3 of 610.  The solder

fillets in some instances could be characterized as being robust.  In

cross-sectional analysis however, the solder joint height of the components

electrical termination above the land has been perhaps 0.025 mm to the point

of needing a SEM to look at the land-solder-component lead interface.

Closer examination in these areas revealed small cracks in the grain

boundaries.  I used the term grain boundaries because the solder in these

areas do not resemble the colonies observed in the bulk solder of the

fillet.  In some of these instances the land is often deformed in the shape

of the component lead.  



 



Would these joints although stronger be more susceptible to fatigue or

overload failure?



What are the implications if these cca's are encapsulated?



What suggestions could be offered to the manufacturer?



 



 



Dale L. Hart



Universal Technology Corporation (UTC)



Failure Analysis



1270 North Fairfield Road



Dayton, Ohio  45432-2600



(937) 656-9165



Fax (937) 656-4600



Email:  <mailto:[log in to unmask]> [log in to unmask]



 





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