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| Reply To: | TechNet E-Mail Forum. |
| Date: | Tue, 19 Feb 2002 19:17:44 +0800 |
| Content-Type: | text/plain |
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Hello eter,
Adhesive dispensing, chip placement, reflow(glue curing), manual insertion, then wave soldering are our normal processes. After reflow we sometimes find some mis-aligned chips or missing components. The area of glue in contact with the surface of the mis-aligned chip could be less than normal and the adhesion force is insufficient to protect the chip from dropping off during wave soldering. Therefore we want to use high temp solder to solder the mis-aligned chips prior to wave soldering. We know that we could detach the parts after reflow and hand solder the parts after the wave soldering but we think adding hi-temp solder is the simpliest way since there is no detachment process is involved.
Eric
----- Original Message -----
From: "Peter Barton" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, February 19, 2002 12:41 AM
Subject: Re: [TN] High temperature solder wire
> If you are going to the trouble to hand solder these parts on why not fit
> them after the wave solder process and just tack them on, applying a dab of
> rework flux first, then reflowing the solder that will be present on the
> pads? Saves the difficulty of using high temp solder pre-wave, and quite
> likely excessive solder on the joints post wave (the solder in your bath
> will wet to the high temp. joints already made). I have seen a similar
> problem when tack soldering large multi way connectors with high temp.
> solder pre-wave.
>
> Regards,
>
> Peter Barton
>
> ===== Original Message from [log in to unmask] (TechNet E-Mail Forum.) at
> 18/02/02 13:40
> >Hi all,
> >
> >We are currently using adhesive to glue chips on PCB and then run the board on reflow oven
> followed by wave soldering. After the reflow process we need to rework some
> chips occasionally due to chip miss-alignment or missing. To do the rework
> we have to remove the original glue, re-glue the chips and let the board go
> through the reflow process again. Now we want to eliminate this loop by
> using hi-temp solder wire (melting point 268-302 degree C) to solder the
> reworked chips without adhesive, then let the reworked board directly go to
> wave soldering with solder pot temperature around 245 degree C.
> >
> >Has anyone using this method seen problems?
> >
> >Eric
>
>
> -----------------------------------------------------------------------
> Peter Barton
>
> ACW Technology Ltd
> Dinas Isaf West
> Tonypandy
> Mid Glamorgan. CF40 1XX Wales
>
> Tel: 01443 425200 Fax: 01443 436882
>
> International Tel : +44 1443 425200 Fax : +44 1443 436882
>
> E-mail: [log in to unmask] Website/URL: www.acw.co.uk
>
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