[time-nuts] Remove Pictic boards from envelopes

[Alan Melia]

I have not been involved in this project but have had pcbs from eastern
sources supplied to RoHS. Some have come in with bare copper pads. I wonder
if the reason for this may be that their standard process was not "tinning",
but it was a a solder-flow stage, and they still have lead-tin solder baths.
So they avoid the one proces involving lead to produce an RoHS produce.
Other manufactures happily produce compliant tinned pcbs.

I found the use of a flux pen was adequate to ensure even lead-free manual
soldering even after the board had been in store for several months. Could
there maybe be a thin flux coating over the pads which is cause the
disquiet?

Alan G3NYK

----- Original Message ----- 
From: "Leigh L. Klotz, Jr WA5ZNU" <Leigh at WA5ZNU.org>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Tuesday, August 10, 2010 6:38 AM
Subject: Re: [time-nuts] Remove Pictic boards from envelopes


>   I tried water, then isopropyl, but what worked was a quick cleaning
> with a white eraser.
>
> Leigh/WA5ZNU
>
> On 08/06/2010 08:15 AM, Ed Palmer wrote:
> > You mean they are tinned?  I received my two boards a couple of days
> > ago.  I thought that they missed the tinning solution.  There's just
> > an occasional splash of bright tin here and there, particularly on the
> > back.  The rest looks like oxidized copper.  I haven't tried to solder
> > them yet.  Hope the rosin cuts through it.
> >
> > Ed
> >
> > Stanley Reynolds wrote:
> >> Please remove Pictic boards from envelopes when you receive them.
> >> Received a report that the tinning on the bottom of the board was
> >> discolored perhaps due to some contamination in the envelope. Will
> >> wrap boards in plastic wrap in the future.
> >>
> >> Stanley
>
>
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