Granted, if I were to have a pc house fab the boards in quantity for commercial
use, I would have them SnPb electroplated and infrared reflowed. Still, most
hobbyists and experimenters aren't going to want to spend that much money on a
single or handful of boards. The link below shows some of the boards I have made
and the effects of no tin plating:
http://www.pic101.com/pcb
Every time I wash my car, it rains. :-(
Rick

Chris Loiacono wrote:

> > I've made thousands myself. Never tinned them, never will.
>  Yeah, but let's look at the real issues here:
>
> 1. tarnished/oxidized copper may get ugly, but eventually, the Copper Oxide
> layer will block the oxidation of the copper beneath the ugly surface.
> Tinning and otherwise plating of etched copper boards originally was done to
> preserve solderability. Boards that would sit in storage for any significant
> time after fab would have to be lightly etched or heavily fluxed before
> subsequent soldering. Strong fluxing became the method of choice, but since
> it was difficult to remove residual flux from these boards, more serious
> corrosion of joints sometimes occurred later on. I think it was US mil spec
> 454 that first required plating to prevent this. Since virtually every board
> house wanted their process lines to comply, it became standard procedure. It
> made no sense to skip such an inexpensive process for commercial boards.
>
> 2. If a board has been well-cleaned of flux residue and the solder joints
> are solid, there's not too much harm that can come from an oxidized surface
> layer, other than reduced cosmetic appeal.
>
> 3. The level of humidity and contamination in the local environment is
> directly proportional to the time it will take for the board to become fully
> ugly.
>
> 4. PCB Plating is a process that is notorious for being poorly controlled.
> Sometimes, a *fresh* copper board will solder better than a week-old plated
> board, so judgment is sometimes required.
>
> 5. Many fab-houses use only solder-tinning for prototype quantities. While
> this may not be a good long term prevention of all oxidation, boards done
> this way seem to solder easily for months afterward, even in very humid
> conditions.
>
> So, unless boards are going to be stored for a while between fab and
> assembly, plating or tinning is not as important as it may seem. If however
> you want your boards to shine and reflect all the effort you put into the
> design, plate or tin them. The best analogy I can come up with is this: Some
> people never wash and wax their cars. Some do. After considering the
> practical side of this issue, this is all that's left.......I think.....
>
> Personally, when I etch my own, I use a cold-plating chemical called ITP,
> from Kepro, which stands for 'Immersion Tin Plating'. CuTech makes this as
> ST225. It's cheap, re-useable, forgiving, and works great. It leaves a real
> tin plating about .2 mils thick.
>
> With board houses out there like Advanced Circuits, Inc. who do excellent
> proto's tinned, masked, and silked for $33, I just cant often justify
> rolling my own very often anymore....The last two jobs I sent them were back
> in 3 days, and were perfect.
>
> Chris
>
> --
> http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> email listserv@mitvma.mit.edu with SET PICList DIGEST in the body

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body