Mr. Ellis

Thanks for your reply,

1.      Yes, you are right, but we were doing this cleaning prior to wave
soldering without any problem but nowadays we experienced the rust problem
before and after wave solder even if we skip the cleaning prior to wave
solder.
2.      We don't make trimming after wave solder.

Regards,

Yousef
        -----Original Message-----
        From:   Brian Ellis [SMTP:[log in to unmask]]
        Sent:   Sun, April 30, 2000 5:45 PM
        To:     TechNet E-Mail Forum.; MOTLAQY
        Subject:        Re: [TN] Rust on lead cutting edge

        Yousef

        2 possibilities, both assuming the leads are a ferrous alloy and
that what you are
        seeing is really rust:
        1. The cut edge of the leads is not tinning during the soldering
because a) the lead
        alloy is not solderable (e.g. containing nickel) and/or the flux
used is insufficiently
        active.
        2. You are using a rotary trimming knife after soldering (many
systems in the past used
        solder-trim-solder)
        In both cases, you have a bare alloy exposed to the aqueous process,
with an active DI
        water followed by a slow drying process: rusting is therefore
inevitable until you
        manage to ensure that the cut ends are tinned correctly.

        This is a known problem.

        Brian

        MOTLAQY wrote:

        > Dears,
        >
        > Below is a short description of a problem we have faced recently
at our
        > plant with the Through/Hole assemblies.
        >
        > Problem: Unacceptable formation of rust (brown to red color) on
the CCA just
        > after cleaning (before and after wave solder)
        > Location: Exactly at the cutting edge of the T/H components leads
(most of
        > the T/H components)
        > Process used: Semi-Aqueous cleaning (Prozone wash 45?C,
Prozone/tap water
        > rinse 45?C, DI water rinse 50?C, then hot air forced drying 110?C)
        >
        > What could be the reasons for this problem and what do you
recommend to
        > solve it and to prevent re-occurrence.
        >
        > Your expected useful response is highly appreciated in advance.
        >
        > Best regards,
        >
        > Yousef Almotlaq
        > Manufacturing Engineer
        >
        > Advanced Electronics Company - Saudi Arabia
        >
        > Email [log in to unmask] <mailto:[log in to unmask]>
        > Tel  + 966 1 220 1350 X 3215
        > Fax + 966 1 220 1355
        >
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