Re: [TN] Delamination at Thermal Via area?Steve,
I was told that the vias are silver epoxy filled. It was bake at 125 degree C for 8hr before going through the reflow.
The same process is repeated on another piece without the component this morning. It was bake and after the first reflow cycle, the thermal via images can be seen. When it was put through another reflow cycle, the same defect can be seen on both sides of the board at that location.
Reading from the responses so far, can I conclude with the followings :
1. There is no need to have filled thermal via as long as there is a matrix of them provided.
2. If filled thermal via is used, the temp profile has to work out to take the filled material property into consideration.
3. While a large piece of thermal pad can be provided on the component side to provide close contact with the component for better heat dissipation, no thermal pad should be used on the bottom side of the board. This will provide an escape route for trapped air if any from the filled thermal via to outgass.
A BIG THANKS to all. I have learned from all of you.
Regards,
Wee Mei
----- Original Message -----
From: Stephen R Gregory
To: TechNet E-Mail Forum ; Wee Mei
Cc: [log in to unmask]
Sent: Wednesday, October 19, 2005 10:29 PM
Subject: Re: [TN] Delamination at Thermal Via area?
Hi Wee Mei!
I've got your pictures posted. Go to:
http://www.stevezeva.homestead.com/files/U2_top.JPG
http://www.stevezeva.homestead.com/files/U2_bottom.JPG
http://www.stevezeva.homestead.com/files/U2_delamination.JPG
Are the vias filled? Are you seeing this delamination on very many
PCB's? Are you seeing it only on the bottom of the PCB?
Kind regards,
-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
Wee Mei <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
10/19/2005 03:47 AM
Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Wee Mei <[log in to unmask]>
To: [log in to unmask]@SMTP@Exchange
cc: (bcc: Stephen R Gregory/LABARGE)
Subject: [TN] Delamination at Thermal Via area?
Hello,
Just asked Steve to download 3 pictures on the defects. Kindly take a look
at them and would appreciate some feedback on the possible root cause.
Steve : Thanks for the downloading.
Regards,
Wee Mei
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