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May 1997

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Subject:
RE: PBGA warpage (assy)
From:
"Yuen, Mike" <[log in to unmask]>
Date:
Thu, 22 May 97 14:00:00 CDT
Content-Type:
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There are many reasons for both the board and the PBGA to warp during 
reflow, and some degree of warpage  in PBGA may not be avoidable. Typically, 
the differences in CTE of materials and cure shrinkage of the encapsulant 
are the main causes of package warpage. Please keep in mind that the 
following factors can have direct impact on the coplanarity of PBGA.  

     - PBGA substrate
          >Thickness
           >Material (BT/FR-4)
     - Encapsulation Material (Glob top vs Molded Top)
     - Thermal Profile during reflow
     - Si Die size  

Hope this helps,
Michael Yuen

 ----------
From: TechNet-request
To: technet
Subject: PBGA warpage (assy)
Date: Thursday, May 22, 1997 1:16PM

I recently had some PBGA's reflowed using a hot air rework
station. All of the PBGA's warped. What could be the cause of the
warpage?
Regards,

Geoff Horrocks
Manufacturing Technology Group

Fitel-PMX
24 Colonnade Road
Nepean, Ontario
K2E 7J6

Phone: 613-723-8939
Fax:   613-723-8349

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