Hello Howard,
Thanks for that feedback. We will look into it further based on your advice.
Unfortunately, this is more than just a soldering issue, as a section of the
tin plated part is compressed against a mating pcba, and we would like a
pure tin interface there.
Best Regards,
Randy Buchter
Product Design Manager
Ranoda Electronics
----- Original Message -----
From: "Howard A. Cyker" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, June 01, 2005 6:39 AM
Subject: Re: [LF] PN's changing - Matte Sn Changing Color
> Hi Randy,
>
> The discoloration you see is most likely caused by impurities (organic
> co-deposits) present in the matte-tin outer layer. Assuming you reflowed
> these parts above the 232 deg. C. melting point of tin, these co-deposits
> would migrate to the surface. You may find that this yellowish outer
> coating is easily removed either mechanically or chemically, and does not
> inhibit solderability. A cross-section comparison between a non-reflowed
> part and the reflowed part should reveal if this is your root cause.
> Tighter control over the tin plating process should prevent this issue.
>
> Good Luck,
>
> Howard A. Cyker
> Senior Manufacturing Engineer
> SynQor, Inc.
> E-mail: [log in to unmask]
>
>
> -----Original Message-----
> From: Leadfree [mailto:[log in to unmask]] On Behalf Of R Buchter
> Sent: Tuesday, May 31, 2005 5:24 PM
> To: [log in to unmask]
> Subject: Re: [LF] PN's changing
>
> Hello All,
>
> We have encountered a concern with a lead free stamped part. It is
> stainless
> steel base metal with 1.27micrometers minimum nickel underplate and 2.54
> micrometers minimum matte tin overplate. The plastic is LCP.
>
> After reflow, the matte tin has a yellowish color.
>
> What could this be and how can it be avoided? Is high solder temperature
> causing this? Does the stainless steel have something to do with it, as
> copper alloy contacts with similar platings do not appear to have this?
> Is
> the LCP a factor?
>
> Thanks in advance!
>
> Best Regards,
>
> Randy Buchter
> Product Design Manager
> Ranoda Electronics
>
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