Dear Kevin,
If brass is wave soldered, the solder joint will be OK, but the zinc
from the alloy will dissolute in the solder and form strong oxide
skins on the solder wave. Therefore brass terminations should be
metallized for wave soldering purposes.
Regards,
Peer Langeveld
Consultant Soft Soldering Processes
5502 VH 8 The Netherlands
2006/8/18, Kevin Glidden <[log in to unmask]>:
> A metallurgist I am not....
>
> We have brass eyelets that we solder wires into. I am unable to obtain
> detailed information on the specific alloy, but the vendor told me it was
> 70% Copper, 30% Zinc. We are soldering using 63/37 solder and RMA flux.
> During soldering, the eyelet appears to change to copper in the non-soldered
> areas. A brief search of some Tech-Net archives has told me that the Zn
> will diffuse out and create solderability problems. But is the end result
> that the material appears to be copper as in my case?
>
> As a side note, I tried a water sol flux and observed the same condition. I
> then tried simply heating an eyelet with an iron - no flux or solder - and
> there was no change, so it appears to be flux related. I also cut a piece
> up to verify it is solid brass, not plated. We tried brushing the eyelet
> after soldering and it appears that you can restore the brass finish to some
> extend.
>
> Anyway, I have confirmed with the supplier these should have been hot solder
> dipped, and we have already ordered replacements. But I am now faced with a
> question I cannot answer - what is the reliability concern of this
> phenomenon, if any? These solder joints get conformal coated, and then the
> entire PCB is RTV'd into a case, so it is well sealed. Can I continue to
> use the existing stock, or is this a serious reliability issue?
>
> Thanks!
>
>
>
>
> Kevin Glidden
>
> Manufacturing Engineer
>
>
>
> Astronics Luminescent Systems Inc.
>
> 4 Lucent Drive
>
> Lebanon, NH 03766
>
>
>
> P: 603-643-7766 x3152
>
> F: 603-643-5947
>
>
>
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