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Date: | Thu, 12 Dec 96 07:42:27 cst |
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Hi Jauwhei Hong -
I can echo Jan's reply - we are soldering SOT's with a dual wave
system with only minor problems. Our flux is a low residue material
that could be used in a no-clean mode. It has been my experience that
the SOT's seem to be a bit less solderable than other components and
that your flux selection will have a big impact on your final solder
joint fillet. Try a couple of different fluxes and see if you get
different results. Good Luck.
Dave Hillman
Rockwell Collins
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______________________________ Reply Separator _________________________________
Subject: Re: (ASSEM) Wave soldering SOT-23
Author: [log in to unmask] at ccmgw1
Date: 12/12/96 5:12 AM
> Tom:
>
> If you are using no-clean flux to solder SOTs (or anything with tall,
> non-solderable body that will repel the wave from reaching the pad,
such as
> tantalum capacitors), dual wave would not work. This is because the
first
> wave (chip or turbulant wave) will kill the flux, resulting in the
poor
> solderability at the second wave (lambda wave). The way we do it
rather
> successfully is to elongate the pad size and solder them with a
vibrating
> wave (omega wave), which has much lower surface energy to reach any
shadowed
> pads. Good luck.
>
> Regards
> Jauwhei Hong
> [log in to unmask]
Jauwhei Hong,
We don't have any problems soldering SOT's with no-clean flux and
dual-wave (chip & lambda). We get fine results if we only use an angle
of 4 degrees, accurate dwell time for the specific pcb and a "perfect"
preheat profile. We also don't have to elongate the pad sizes, we use
the ordinary sizes the pick & place do.
i don't know, but are we different?
/Jan Merstrand
Operation Engineer
Ericsson Microwave Systems
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