Steve
If it's only the fillet that's blue, don't worry: it's only a light
oxidation of the alloy, probably due to a slightly higher-than-usual
temperature/time during drying. It is totally harmless and must NOT be
retouched. Do NOT be more royalist than the king!
What disturbs me more is that your solder mask appears blue to the left
of the fillet. Is this something that is purely optical in the photo or
is it real?
Brian
"Stephen R. Gregory" wrote:
>
> Hi ya'll!!
>
> It's picture time again. Just to let ya'll know, Driveway is discontinuing
> the free storage, sharing service that it once had, service will stop March
> 5th (that's what I've been using in the past).
>
> They offer to do the same service at another place: www.freedrive.com...the
> only problem is that for anyone to view a file that someone has, you have to
> sign-up as a user...maybe not a big deal, but I like to post a URL and let
> everyone see something without the sign-up hassles. So I found another
> free-drive place:
>
> http://www.xdrive.com
>
> You have 25-megs of space for free...
>
> So, go to: http://www.xdrive.com/share/983237599927EkdOzD4nV39P1mRq3zXk
>
> and look at this picture, it's called bluesolder.jpg. It is of a solder joint
> that our inspectors are calling "blue solder"...(in fact they have a PQI code
> for it, acronyms again, Process Quality Indicator) it does have a light
> "bluish" tint to it. What may appear in the photo as some sort of residue,
> doesn't seem to be, it doesn't clean off at all. I've tried taking an acid
> brush with alcohol and scrubbing the surface...it doesn't touch it, it's like
> it's something in the surface of the solder joint. I've done a omegameter
> check, and nothing comes up as being ionic...
>
> The board was wave soldered with a RMA flux, and cleaned with Kyzen Aquanox
> and deionized water at the recommended concentrations. From what I've
> gathered from people that have been here a lot longer than I have, they have
> seen this before...but nobody knows what causes it...in they past they have
> touched-up every single joint to get rid of this appearance, which to me is
> kinda' ridiculous. We waved three boards, and two of them have this
> condition, and one doesn't. They were all waved at the same time...
>
> The large grain structure that you may notice in the photo is because (I
> think) of the long cool-down time this assembly takes after wave...all the
> parts are ceramic, and there's some heavy metal planes in this board. It goes
> without saying that the wave profile I have to use to get good topside
> fillets is pretty hot compared to other boards (it's polyimide, so the fab
> can take the heat)...could that be something that is causing this appearance?
> But why two boards, and not all three?
>
> I have good wetting, and all other visual appearances look fine...it's just
> this "Blue Looking Solder"...any ideas? BTW, our customers source inspector
> accepted the boards, even after pointing this appearance out to her, but our
> QA wants it to look better when we ship it....YAAAAAAA!
>
> Thanks!!
>
> -Steve Gregory-
>
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