Homebrew PCBs

I read on the MG Chemical site that it's un-necessary to tin a PCB
if you use the photo-resist method.

Here's the link
It's #5 at the bottom of the web page
http://www.mgchemicals.com/techsupport/proto_pos-inst.html

What do you guys think?

On 23/09/2010 07:48, acidblue wrote:
> I read on the MG Chemical site that it's un-necessary to tin a PCB
> if you use the photo-resist method.
>
> Here's the link
> It's #5 at the bottom of the web page
> http://www.mgchemicals.com/techsupport/proto_pos-inst.html
>
> What do you guys think?


I don't bother tinning my boards even if I have cleaned the resist; the 
very thin film of resist that is left after cleaning it off prevents the 
copper from tarnishing, and doesn't impede soldering. As they say, it 
can be left on, and I sometimes do that if I don't have any fine-pitch 
devices. It's quite easy to solder through it.

Leon
-- 
Leon Heller
G1HSM

On Thu, 23 Sep 2010 06:48:34 -0000, you wrote:

>I read on the MG Chemical site that it's un-necessary to tin a PCB
>if you use the photo-resist method.
>
>Here's the link
>It's #5 at the bottom of the web page
>http://www.mgchemicals.com/techsupport/proto_pos-inst.html
>
>What do you guys think?
>

Might be true if you're using through hole stuff exclusively, and
large traces.

I'd still feel better using tinned boards if I were doing SMT stuff.

Since I don't do photoetch right now, I tin the boards anyway.

Harvey

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I just switched over to the photo-resist method, so far I love it.
Just wasn't getting consistent results with toner transfer, prolly due
to not using a laminator, also laminaotrs are not cheap.
I made my exposure unit for about $12.

So far I'm using thru hole components exclusively, and my traces are
.020-.025, might go as low as .015.

So I prolly don't need to tin my boards.
Now If I can just find a cheap source of presensitized boards everything
would be just great.
Checked ebay and there wasn't any that I could find.

Stephen Lane wrote:
    the reason you remove the Photoresist is for joint high reliability when you solder the photoresist which is a plastic polymer of some sort, it degenerates to various nasties which can cause corrosion later in time this is the same reason you should wash the left over flux off the board after you have finished soldering (its often hygroscopic & again will promote eventual corrosion of your joints) however if you coat your finished assembled board with a conformal coating washing the flux isn't so critical.

Regards
Stephen 

--- In Homebrew_PCBs@yahoogroups.com, "acidblue" <sunblaster5@...> wrote:

>
> I read on the MG Chemical site that it's un-necessary to tin a PCB
> if you use the photo-resist method.
> 
> Here's the link
> It's #5 at the bottom of the web page
> http://www.mgchemicals.com/techsupport/proto_pos-inst.html
> 
> What do you guys think?
>