Manuel,
there are several things that seem anomalous:
1. Looks like Copper is exposed at the end of some leads. Gives the impression of poor lead finish.
2. The solder spheres are not fully melted at the outermost part of the solder pad. Due to short top temp zone exposure?
3. Some solder pads are not wetted 100% or have dewetted. Looks like bad finish.
4. The solder mask is very close to the solder pads. Maybe you get solder mask contaminations on the solder pads.
5. The leads seem to be lifted during the soldering process.
6. Youd can't see the whole solder joint. Is the innermost part of the solder joints as bad as the outermost ones?
7. The colour of the non-wetted ( or de-wetted )part of the solder pads tells me that the solder pad finish is bad.
I've never seen so many divergences at one and the same positions. A first look gives the impression that the solder paste was bad, that the lead finish was bad, that the solder pad finish was bad and that the soldering process was incorrect. Of course that's not a correct analysis. Question is which one is the bad guy. I suspect that not even the TN gurus can decide without knowing a little more. E.g. what soldering process was used? What solder paste? How do the other component's SJs look like? What's the size of the board? What mass? What pre-clean process? What stencil thickness? Etc.
If I do my best guessing, I vote for local poor solder pad finish. I will enjoy reading the correct analysis later from someone of the heavyweighters in the game...
/Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of stephengregory5849
Sent: måndag 26 oktober 2009 02:41
To: [log in to unmask]
Subject: Re: [TN] Questions
Hi Manuel,
I'm sorry I didn't get your pictures posted sooner, but I have them up now, and I'm posting everything to the TechNet for you. Your pictures are here:
http://stevezeva.homestead.com/1a.JPG
http://stevezeva.homestead.com/2a.JPG
http://stevezeva.homestead.com/3a.JPG
http://stevezeva.homestead.com/5a.JPG
I posted the pictures that looked the best to illustrate your problem, a couple of pictures were out of focus and it was hard to see the problem.
Were the IC's the only component that had this problem? That pretty much eliminates the solderpaste if it was. It makes it harder to figure out when you say that it was random and only on three boards. What was the lead finsh on the IC's? I've had a few problems with lead-free (tin) plating, but it's been with connectors.
Steve
----- Original Message -----
From: Manuel Castro
To: [log in to unmask] ; Werner Engelmaier
Sent: Friday, October 23, 2009 7:00 PM
Subject: Re: Questions
Steven,
Attached are the photos of the issues. We run this assembly through our SMT oven and got a few boards (3) with this phenomenon at some of the leads on this FPIC. The IC was the same part number but the location was random on all 3 boards. The chemistry utilize during this build was Lead Free NC.
How do I send the email to everyone at the TechNet forum?...
Thank you All...
Best regards,
Manuel Castro Jr.
Senior Process Engineering Manager
[log in to unmask]
Office: (408) 964-3044
Fax: (408) 964-3001
On Fri, Oct 23, 2009 at 1:14 PM, Werner Engelmaier <[log in to unmask]> wrote:
Hi Manuel,
Steven is the GOOD guy doing the posting on his website-he recently changed jobs, e-mails, etc.; so it might be best to ask him directly.
Werner
-----Original Message-----
From: Manuel Castro <[log in to unmask]>
To: [log in to unmask]
Sent: Fri, Oct 23, 2009 1:11 pm
Subject: Questions
Hi Werner,
I love to follow all TechNet forum but I still don't know where the picture get posted from everyone that has an issue. Can you kindly tell me what the link is. Do we need a password to access the pictures. Lastly, if I have an issue where do I post the picture to share with the team or whom do I sent it to?
Best regards,
Manuel Castro Jr.
Senior Process Engineering Manager
[log in to unmask]
Office: (408) 964-3044
Fax: (408) 964-3001
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