GA Tan...

A couple of questions....
Pitch and ball size of BGA
PCB pad size
PCB material and thickness
Underfill material
What solder and ball metalllury
Top and bottom heater temps
Time above 230C
Cooldown ramp rate
How was 16G force generated  and how was the coupon mounted to the generator


Paul

Paul Edwards
Surface Art Engineering

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tan Geok Ang
Sent: Wednesday, January 14, 2009 5:27 PM
To: [log in to unmask]
Subject: [TN] Possible cause on open

Hi Steve,

            Please help to download these pictures TechNet, thanks.







Hi All experts,

            Testing (combine test of 16G at 85 oC) was performed on
evaluation boards with under-filled BGAs. Open issue (cracks) was
detected only at some corners of the BGA (35x35mm with 1156 balls) after
the test. Lead-free process and PCB with ENIG surface finish. Peak
temperature is 248 oC with a 65 sec above 217 oC.

FYI, the service lab has not come out a report.

            What are the possible causes? (CET mismatches, Lead-free
alloy related, material, processes)



            Thank you in advance.



Regards

GA Tan




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