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August 2000

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Subject:
From:
Ed Valentine <[log in to unmask]>
Reply To:
Ed Valentine <[log in to unmask]>
Date:
Tue, 29 Aug 2000 08:49:40 -0400
Content-Type:
text/plain
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text/plain (62 lines)
Bing - I'm not sure I fully understand what you are saying but let me
respond by saying that for large IC's (QFP's, BGA's, PLCC's, etc.) you can
get some unsoldered joints due to board warpage and poor lead coplanarity.
Among several causes, the most common board warpage problems I've seen
during reflow are usually due to uneven copper distribution in buried power
and ground planes of multilayer boards. Unfortunately, the drawing you said
you had attached to the email was not included on the TechNet distribution.

Ed Valentine
Electronics Manufacturing Solutions
8612 Mourning Dove Road, Raleigh, NC 27615
Phone: (919) 270-5145, Fax: (919) 847-9971
Email: [log in to unmask]
Website: http://www.ems-consulting.com

----- Original Message -----
From: "Milanie Racuya" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 28, 2000 9:33 PM
Subject: [TN] unsoldered joint


> Guys, good day
> I've got some queries regarding warpage of the PCBA after reflow which
> could cause unsoldered joint on one of the IC's. Almost 20% of the lower
> left corner of the board is removed and I think that the tension is not
> evenly distributed. Is this idea correct? Please see attached drawing
> for you guys to visualize what I'm trying to tell you.
>
> Thanks,
> Bing
>
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