Steve will typically post a link to the specific pictures. To view his "wall of shame" go to http://www.stevezeva.homestead.com/
Blair
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Wednesday, April 25, 2007 4:24 PM
To: [log in to unmask]
Subject: Re: [TN] SV: [TN] Quadpack solder joint failures
Evamaria:
Steve Gregory usually post them on his webpage and let the forum know through an E-Mail with a link to the pictures.
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jones, Evamaria
Sent: Wednesday, April 25, 2007 4:19 PM
To: [log in to unmask]
Subject: Re: [TN] SV: [TN] Quadpack solder joint failures
Where is Steve's Center of Wicked Pictures?
Evamaria Jones
Quality Assurance Specialist
Electronic Manufacturing Skills Instructor General Dynamics Information Technology
(703) 874-6796 direct
(540) 522-8823 cell
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________________________________
From: TechNet on behalf of Hfjord
Sent: Wed 4/25/2007 1:18 PM
To: [log in to unmask]
Subject: [TN] SV: [TN] Quadpack solder joint failures
Hi Werner,
What I'm consternated by is the presence of Nickel where it's not expected to be. The Quad is soldered on ENIG with 60Sn. Typically, the solder flows a bit on outside of the board pads. The joints are strong.
The Quad is drowned with a 15 Tg coating. The coating fills the space around the leads, but does not fill the space between Quad and board. I have polished samples of the board from the backside until I can see the underside of the copper pads. On the photos, I can see the copper with its nickel all around. On outside of the nickel I can see the solder. So far it's normal. BUT, on the perimeter of the solder, I can see nickel again, as well as nickel traces in the solder. Thought at first, that it was smear, but whatever method we use, the result is the same. Normally, such a lot of nickel can't be dissolved that short solder time at that low temperature. The nickel along the perimeter is several micrometers thick. I have seen poor nickel plating lifted from Kovar and flow around as flakes in the solder, but never seen nickel leave copper that way.
The product is used all around, and works good, the solder joints being acceptable, but a few failures have been reported, i.e. one or two or three leads get solder joint cracks and electrical disrupts. Not many, but enough to make us suspicious. Randomly appearing, as it seems. No red thread. Various places, various operating time, various everything.
My guess was that we have to do with some metallurgical issue, like 'black' pads or any other of the frequently discussed topics in this forum, but the leads don't lift from the pad, instead the rupture is typically somewhere between the IMC region and the Quad's lead.
Before start digging, I would like to get an idea about the strange behaviour of the nickel.
First pic shows the pads from the underside Next two pics show nickel in the solder that flowed outside the pad. He who is wise will see.
If someone got an idea, it would be you, Werner (lot's of butter)
Inge
PS. Sending my three photos to Steve's Center of Wicked Pictures
-----Ursprungligt meddelande-----
Från: [log in to unmask] [mailto:[log in to unmask]]
Skickat: den 24 april 2007 23:38
Till: [log in to unmask]; [log in to unmask]
Ämne: Re: [TN] Quadpack solder joint failures
Hi Inge,
FEA is not the savior when the wrong material properties are input [Watch for my next column in GSMT&P on this subject].
But you are not giving us much to go on-is there in fact an "airgap between Quad and board" or is that filled (even partially) with the conformal coating given the robotic "drowning." An even lifting indicates a pretty uniform vertical displacement. Remember, this stuff, particularly in a confined space, is essentially non-compressible.
Werner
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