Homebrew PCBs

On Mon, 1 Aug 2016 06:50:27 +0200, you wrote:

>There you go again, poisoning the squirrels.
>
>I did something much like HASL when I still made boards, what you can
>do is you buy a can of plumbing solder paste (the solder bearing
>kind). This is tin only solder so you don't need to worry about the
>waste, and it's much cheaper than SMT solder paste for electronics.
>Then you dilute it to a consistency you can paint with a brush, just
>with water. Paint that on your board, heat with air gun to reflow. The
>excess on bare surfaces just washes off.
>This leaves a pock-marked matte surface, if you want it smooth and
>shiny you can wipe off the excess with a paper towel while still hot.
>Does the same as air leveling but much more practical at home.
>Mind to wash the flux off well, since it is not electronics flux. It
>is water soluble since it is designed for plumbing and hot water takes
>it right off.

I may try this, it seems lots better than immersion tin.  Right now,
I'm in a software phase of development, much cheaper than making
boards.  Some boards are at the production phase, so I've got a design
that works, I'll just possibly need more of them.

>
>I briefly considered building a roller tinning machine, basically two
>rollers between which the PCB is fed, with the lower out of metal and
>immersed in a solder bath at the bottom. The whole thing is heated and
>you just feed the board through. I was told it works fine but keeping
>the solder bath free of dross is a bit of a pain, requiring special
>flux. You can find pictures with google, they are used commercially.

Before I did something like that, (unlikely), I'd try to make a
etchant system with a pump for more even etching.  May end up with a
peristaltic pump and silicone tubing.
>
>That said, the vast majority of boards I simply coated in colophony
>resin (rosin) flux. This is so mild it doesn't cause corrosion, and
>with denatured alcohol (ethanol) it can be made into a nice laquer.
>Since it is a flux it is great to solder and protects the copper from
>oxidation for a long time. They even make a spray can so you don't
>need to mess with the sticky paintbrush.
>

Now that seems to be the simplest one, so that's on the list, too.

Thanks for the suggestions:

Harvey

>ST
>
>On Mon, Aug 1, 2016 at 6:06 AM, Harvey White madyn@...
>[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>> On Mon, 1 Aug 2016 05:45:53 +0200, you wrote:
>>
>>>RoHS allows 0.1% lead.
>>>
>>>I think this Liquid Tin is based on thiourea, something much, much worse
>>>than lead. Remember to wash your hands and wear a hardhat or something ;-).
>>
>> I think it is.  It comes with lots of warnings, most of which involve
>> the word "poison".
>>
>> I use gloves and tongs, and wash the boards thoroughly. Also, this is
>> done quite outside the house.
>>
>> Wonder if I could do something like HASL....
>>
>>
>> Harvey
>>