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| Date: | Thu, 7 Oct 2010 14:59:13 +0000 |
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You would have to inspect a board right after it comes out of the placement machine to see if paste is pushed out or there is any smearing. Much of the small variances are gone after reflow. A second inspection after reflow would establish whether there is a problem or not. However if the setup of the bottom supports is not being done exactly the same way from one setup to another you could be looking at a marginal problem that was occurring that day but could be worse on other runs. A good process must be repeatable and that starts with setup.
In general the bottom supports should have been in place to prevent deflection and board bounce that can effect the alignment of other parts that were placed earlier in the placement sequence, especially MELF (round bodied parts), tall narrow SMT connectors.
John Goulet
Process/MFG Engineer
----- Original Message -----
From: "Dale L CTR USAF AFMC AFRL/RXSA Hart" <[log in to unmask]>
To: [log in to unmask]
Sent: Monday, October 4, 2010 2:26:04 PM
Subject: [TN] pick and place /board deflection
I was on the shop floor and noticed deflection in the 8x8 inch panel that
was being populated. Would the deflection in the middle of the panel cause
components to sit higher on the paste and thus have a slightly higher solder
joint height than components on boards along the rails? Thanks in
advance
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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