Can't you use micro-XRF? flash is hard to x-section and detect even
using SEM (unless very good at polishing without smear)... jk
On Dec 29, 2007, at 6:15 PM, Hfjord wrote:
> 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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