Nickel flash! You'd better tell us the whole story, e.g. post the datasheet
to Steve or give a link. Agree with George, make Xsection, takes half an
hour with fast acrylic, 600+2500 paper polish, dip a few seconds in an acid
solution, just for making a topographic contrast, put the sample in a SEM
with backscatter detector and see if the layers are thinner than let's say
2-3 micrometers (you can't do any precision measurements this way). If both
tin and nickel is thinner than that, I'd recommend pulling the emergency
brake and do what George recommended.
So....Christmas is over for many...I'm lucky to have a few days more as
free...ZZZZZZZZZZZZ
Inge
PS. Forgot to tell you, if you are not used to sample preparation: use a
whole bunch of resistors, not just one! There may be variations too....
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Wenger, George M.
Skickat: den 28 december 2007 19:05
Till: [log in to unmask]
Ämne: Re: [TN] Hand Soldering Matte Tin over Nickel Flash with SnPb Alloy
I think the first thing I would do is to determine what p
Chris,
I think the first thing I would do is to determine what part of the
component surface I was soldering to by running a trial and by doing
cross sections. The trial would be to solder side by side a component
that had formed leads and one that didn't have formed leads. I would
also cross section two other components (one with formed leads and one
without)before soldering to see if the soldering problem is due to the
fact that the forming process exposes nickel in the area that is being
soldered. I'd also do a third evaluation and us an XRF to measure the
thickness of the Sn and the Ni on the component leads both before and
after forming. It might just turn out that you're having solderability
issues because you're soldering to exposed Ni rather than matte Sn.
Regards,
George
George M. Wenger
Andrew Corporation Wireless Network Solutions
Senior Principal FMA / Reliability Engineer
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 [Office] (732) 309-8964 [Cell]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Schaefer
Sent: Friday, December 28, 2007 12:00 PM
To: [log in to unmask]
Subject: [TN] Hand Soldering Matte Tin over Nickel Flash with SnPb Alloy
Greetings All,
I have a PTH TK type resistor component that is formed to fit an SMT
geometry land pattern. The component is Pb Free component plated using
Matte Tin over Nickel Flash. Once the component is soldered it exhibits
non-
wetting/ poor wetting characteristics thus causing us to rework until we
have
achieved acceptable results. Of course this is not what I would like to
see
occur, but unfortunately at this time it is the process. The
installation process
is as follows:
- Part is formed using a lead forming tool
- Is tinned using 25% RMA for 3 seconds and let to dry (somewhat); then
soldered (SnPb tin/ lead alloy) for 3-4 seconds in a 600F bath
- It is soldered (SnPb tin/ lead alloy) to the cca using a 6ooF solder
iron tip for
2-3 seconds
- END...
Apparently this has been an issue for years, but just recently was
brought up
to our Engineering department. We tin the component to allow for
improved
wetting characteristics, but this does not provide much improvement. I
have
done some investigation on the internet looking for reports and tests
performed soldering Matte Tin over Nickel using standard Tin/ Lead
alloy, but
have found very little information regarding this. The component
manufacture
states our process as described to them 'should work without issue, but
this is
not the case.
So my questions are what are the issues related to soldering matte tin
over
nickel flash with tin/ lead alloy? What hand soldering parameters are
considered optimal/ ideal with a low-mass matte tin plated component
considering the information provided? Is it possible to get very similar
results
using this combination of metallurgies versus using tin/ lead plating
and solder
materials?
Any help would be appreciated.
Thank You,
Chris
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