Hi Linda,
I was having some warpage issues at one point with some components during
SMT thermal profiling. I found this company very useful you might want to
give them a shot. The company name is "Sonoscan". What they do is what is
call imaged acoustically with C-SAM using the interface scan imaging
tehcnique. This will tell you wether the interior of the package is under
stress or has been damage during reflow temperatures.
http://www.sonoscan.com/
Best regards,
Manuel Castro Jr.
Senior Process Engineering Manager
[log in to unmask]
Office: (408) 964-3044
Fax: (408) 964-3001
On Tue, Oct 13, 2009 at 7:23 AM, Stadem, Richard D. <
[log in to unmask]> wrote:
> Hi, Linda
> I think what you may be seeing is more commonly called pad cratering, a
> common issue with lead-free soldering. This shows up mostly on BGAs with
> their relatively non-compliant connections, rather than gullwing leads.
> However, I have seen it happen on gullwing connectors, where the body of the
> connector is fastened to the PWB such that the compliant leads pull so hard
> as to lift the pads during reflow and cooldown. This can be confirmed using
> shadow moiré photography, where the image is strobed a number of times
> during the temperature cycle in order to show the physical movement that
> takes place.
> Rather than pursuing the visible confirmation of lead coplanarity during
> reflow using shadow moiré photography, you may be better off researching the
> cause/corrective actions of pad cratering.
> Simply search the archives of Technet or Google up the term "pad cratering"
> and you will get a wealth of information, causes, and corrective measures to
> eliminate the issue. It can be caused by a number of design and process
> factors working together.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Linda Langley
> Sent: Tuesday, October 13, 2009 9:02 AM
> To: [log in to unmask]
> Subject: [TN] Lifted Leads
>
> Linda
>
> I know that you are signed on TechNet
>
> Could you please post question to all experts for me:
>
> We are reflowing 50pins CF card SMT connector and having high rate of the
> lifted leads (they are gull wings leads). We measured leads co planarity
> using CMM before reflow and it seems that all leads are meeting the spec.
>
> My guess is that the component body is bowing during reflow process (we are
> dong Pb free reflow with the peak of 234°C) causing lifted leads.
>
> Somebody told me that there is a lab who can measure leads co planarity
> during reflow cycle. Is anybody aware of such as test?
>
> Thank you
>
>
>
> Can anyone share some information, any help will be greatly appreciated.
>
>
>
>
>
> Linda Langley CIT
>
> Training Specialist
>
> Jabil Circuit
>
> 248-292-6176
>
>
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