Ed,
Do you use a "window pane" or similar stencil design to help give the flux a path from the thermal pad during the first reflow?
Also one of our paste products says it's rated for ramp to spike and ramp soak spike but only has low voiding when we soak. Only found this out by speaking to the Customer Technical Support Engineer.
Jerry Dengler
Production Manager
Pergamon Corporation
380 Crooked Lane, Unit# 3
King of Prussia, PA 19406-2567
U.S.A.
(610) 239-0721 Phone
(610) 239-0720 Fax
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ed Popielarski
Sent: Friday, May 08, 2015 2:23 PM
To: [log in to unmask]
Subject: Re: [TN] Dpak outgassing second pass
1. How much time between first and second reflow? Is there enough for the board to absorb moisture which causes the outgas?
Only an hour or two. Likely not re-absorption.
2. Could the outgas be from trapped flux? A longer TAL during first reflow may help if this is the case.
Absolutely. The first reflow has voiding in the thermal pad area due to flux in paste, I'm sure it remains resident and "erupts" during second reflow (side 2)
3. Can you lower the bottom side temperature during the second reflow? Since you have big heavy components on the top side probably not.
No, these are 8 layer 2oz. power assemblies and it needs all the heat we can muster for side 2 (top) with very heavy inductors.
Ed Popielarski
Engineering Manager
970 NE 21st Ct.
Oak Harbor, Wa. 98277
Ph: 360-675-1322
Fx: 206-624-0695
Cl: 949-581-6601
"It's one kind of victory to slay a beast, move a mountain, and cross a chasm, but it's another kind altogether to realize that the beast, the mountain, and the chasm were of your own design."
https://maps.google.com/maps/myplaces?hl=en&ll=48.315753,-122.643578&spn=0.011188,0.033023&ctz=420&t=m&z=16&iwloc=A
-----Original Message-----
From: Jerry Dengler [mailto:[log in to unmask]]
Sent: Friday, May 08, 2015 11:22 AM
To: TechNet E-Mail Forum; Ed Popielarski
Subject: RE: [TN] Dpak outgassing second pass
Hi Ed,
1. How much time between first and second reflow? Is there enough for the board to absorb moisture which causes the outgas?
2. Could the outgas be from trapped flux? A longer TAL during first reflow may help if this is the case.
3. Can you lower the bottom side temperature during the second reflow? Since you have big heavy components on the top side probably not.
Good luck,
Jerry Dengler
Production Manager
Pergamon Corporation
380 Crooked Lane, Unit# 3
King of Prussia, PA 19406-2567
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ed Popielarski
Sent: Friday, May 08, 2015 1:08 PM
To: [log in to unmask]
Subject: [TN] Dpak outgassing second pass
Greetings fellow Technoids,
An interesting debacle arose, and I'm unsure if there is a solution.
Dpak components on side 1 solder fine, <25% voids, 100% edge wetting.
On 2nd pass (top side, big heavy components) the Dpaks on side 1 outgas and exceed 25% (not a spec, just a target) but violate edge wetting (S/B 100%) as the outgas tends to blow out the edge somewhere.
Any suggestion on how to eliminate this phenomena? Parts cannot be relocated due to aerospace re-qual cost.
Thanks in advance!
Ed Popielarski
Engineering Manager
[cid:[log in to unmask]]
970 NE 21st Ct.
Oak Harbor, Wa. 98277
Ph: 360-675-1322
Fx: 206-624-0695
Cl: 949-581-6601
"It's one kind of victory to slay a beast, move a mountain, and cross a chasm, but it's another kind altogether to realize that the beast, the mountain, and the chasm were of your own design."
https://maps.google.com/maps/myplaces?hl=en&ll=48.315753,-122.643578&spn=0.011188,0.033023&ctz=420&t=m&z=16&iwloc=A
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