I checked the profile, it's OK, I don't burn the flux.
Didn't pass the glass plate, but I played a lot with the immersion of the
PCB, with no result.
I don't use any fixtures.
And one thing I forgot to mention is that we already soldered the previous
revision of the same assembly, with no problem at all.
Thanks,
Ioan
> -----Original Message-----
> From: Campbell, William (wcampbel) [SMTP:[log in to unmask]]
> Sent: Wednesday, April 04, 2001 3:57 PM
> To: [log in to unmask]
> Subject: Re: [TN] Random absence of soder joints
>
> Just a thought- Check your pcb temp just before wave. You may be cooking
> the flux off before it gets to wave, but most likely you're just not deep
> enough, esp with selective flow fixtures.
>
> -----Original Message-----
> From: Tempea, Ioan [mailto:[log in to unmask]]
> Sent: Wednesday, April 04, 2001 2:43 PM
> To: [log in to unmask]
> Subject: [TN] Random absence of soder joints
>
>
> Hi,
>
> some time ago, Mike Bailey brought up a situation of random non-wetting on
> the secondary side. Well, I run into a somewhat similar problem right now.
>
> After wave soldering, I see SMT passives that are on the solder side
> exhibiting either non-wetting at all, or one side soldered while the other
> one looks just like before the wave, no sign of wetting. Even on the pads
> without components, the situation is the same, some pads have absolutely
> no
> trace of solder, while the adjacent ones collect solder without any
> problem.
> Not related to shading, since bad spots are even far from any component.
> Not
> related to glue contamination either, since I have trouble even with pads
> without components.
>
> To make it even more complicated, there is no problem to hand solder the
> non-wetted pads, after the wave.
>
> I refreshed the flux, ran the assemblies on two totally different machines
> (different preheating, fluxing), with the same poor result.
>
> The process is:
> glue & insertion + reflow at 120C for the bottom side, only passives
> populated
> paste & insertion, reflow for the top
> wave with no-clean X33 flux from Multicore and regular eutectic solder
> board is HASL
>
> I know this is a mild flux, but it does a great job for us on much more
> demanding assemblies. I will try a stronger one, but cleanliness is a big
> issue.
>
> Now, I would like to know if Mike found something and if he could fix
> anything.
> Besides that, any hint that Technet could give would be largely
> appreciated.
>
> Thank you,
> Ioan
>
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