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May 2010

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From:
"Nowland, Russell Howard (Russell)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Nowland, Russell Howard (Russell) <[log in to unmask]>
Date:
Thu, 20 May 2010 08:17:28 -0500
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Angelo,

Ioan and Bev are correct in what they are telling you.  Just as an added note SMT components are supposed to be able to withstand a minimum of three reflows without degradation to the device.


Russell Nowland
Alcatel-Lucent
Advanced Manufacturing Engineer
Address: 14000 Quail Spring Parkway, Suite 300
Oklahoma City, OK 73134
email: [log in to unmask]
Desk: 405-302-1660
Cell: 405-203-0034
Fax: 405-302-1622
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Thursday, May 20, 2010 7:27 AM
To: [log in to unmask]
Subject: Re: [TN] Second Reflow

It should work if compliant with Bev's points, but remember: you cannot just pass them through the oven with the right profile, as the original flux is gone.

Spraying them with wave flux might or might not help, the best is using gel flux, the same as the one used in your solder paste. Long procedure, as you need to smear this gel all over.

So the question is: are the boards no-clean or washable? If no clean, the result will be messier than usual! And this will only fix the other poorly soldered components, the tombstoned parts are gone, you'll need to fix them one by one with the iron.

And the bigger question is: how can 50 boards be soldered without anybody realizing there was a problem? You should revise your first-off inspection procedure... and never run a line without inspectors at the end of the oven.

Good luck,

Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
E | [log in to unmask]
W | www.digico.cc

N'imprimer que si nécessaire - Print only if you must


----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Thu May 20 07:48:12 2010
Subject: [TN] Second Reflow

We had an order of 50 PCBs that after reflow, it was discovered that we had
tombstoning and quite a few components that didn't solder correctly. We have
traced it to the operator using an incorrect profile. I've been in the business
long enough to remember that you could run a board through the wavesolder
twice, without damaging it. Does the same apply to reflowing SMT? Can I re-
run the boards through the reflow oven again? We are a small ECM that has
been in business for 20+ years and we have never had this happen before, but
I am hoping someone can help me out.


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