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December 2003

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Subject:
From:
Vladimir Igoshev <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 19 Dec 2003 10:23:08 -0500
Content-Type:
text/plain
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text/plain (103 lines)
Hello Seppo,

Underfill will definitely "save" you from having cracked joints (particularly due to drops), but it's a "painful" procedure.

Regards,

Vladimir

Vladimir Igoshev
Research in Motion

-----Original Message-----
From: Seppo Saario [mailto:[log in to unmask]]
Sent: Thursday, December 18, 2003 8:49 PM
To: [log in to unmask]
Subject: [TN] BGA Underfill comments/recommendations


Dear All,

I am doing some checking into the effectiveness of BGA underfill on mobile
handsets.
Typically handset boards have 3-4 BGA's (0.5 to 0.8mm pitch) and have seen
handsets with and without underfill.
PCB thickness is 0.8mm

Has anyone seen any studies, or have any comments on the reliability of BGA
joints wrt underfill.
Also, any comments on what typically recommended underfill compounds are is
also appreciated.

Thanks in advance! - and wishing you all a Merry Christmas and a Happy New
Year !.

--
Seppo Saario
Voxson Ltd., Core Technologies - Hardware
Design Engineer
Tel +61-7-3268-0745 ; Fax +61-7-3878-1370



-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Friday, 19 December 2003 10:20 AM
To: [log in to unmask]
Subject: Re: [TN] Need your opinion


I would agree with the shearing rather than routing of the edges.  With the
severe crazing that extends to the ball area, it is a realiability issue.
The cracking of the solder mask is a real concern and indication that the
edges are suspect.

Susan Mansilla
Robisan Lab

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