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" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]> 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 > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
