Homebrew PCBs

With all this talk of "proper" solder masks, I thought I'd ask about  
some more rough-and-ready options.

I've just successfully replaced the guts of my bike's tail light (with  
a PIC 12F6x and a lot of 0603 LEDs). Although it's sealed into a  
watertight box, I'm going to need to seal the copper against long term  
corrosion. It's a nice small board so I'm thinking of either painting  
it with urethane (e.g. varnish) or I thought it might be more durable  
but viable (given the smallness) to just paint it w/- araldite - a  
crude but effective "2-pack epoxy". That would write off a paintbrush,  
but be pretty tough.

The reason for painting is to avoid the LEDs, or I'd just dip it.

Anyone tried it? Am I crazy? etc?

PG

I don't know if you are crazy, but it sounds like a plan to me.  But why not just dip and coat the LEDs as well?  If the araldite is sufficiently transparent, I don't think it would change the light emission, and might toughen the surfaces exposed to the elements.

WOW!  A PIC controlled tail-light.  My bike is not so fully equipped :)
Donald.

----- Original Message -----
From: "Piers Goodhew" <piers@...>
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, September 7, 2009 7:35:07 PM GMT -05:00 US/Canada Eastern
Subject: [Homebrew_PCBs] Super QAD soldermask options

With all this talk of "proper" solder masks, I thought I'd ask about  
some more rough-and-ready options.

I've just successfully replaced the guts of my bike's tail light (with  
a PIC 12F6x and a lot of 0603 LEDs). Although it's sealed into a  
watertight box, I'm going to need to seal the copper against long term  
corrosion. It's a nice small board so I'm thinking of either painting  
it with urethane (e.g. varnish) or I thought it might be more durable  
but viable (given the smallness) to just paint it w/- araldite - a  
crude but effective "2-pack epoxy". That would write off a paintbrush,  
but be pretty tough.

The reason for painting is to avoid the LEDs, or I'd just dip it.

Anyone tried it? Am I crazy? etc?

PG

On 08/09/2009, at 9:49 AM, Donald H Locker wrote:

> I don't know if you are crazy, but it sounds like a plan to me. But  
> why not just dip and coat the LEDs as well? If the araldite is  
> sufficiently transparent, I don't think it would change the light  
> emission, and might toughen the surfaces exposed to the elements.

I reckon the araldite would cost you a few dB of refraction/ 
reflection. I guess I can easily test on one of the 5x0603 LED with  
header pin breadboard testers I made.

> WOW! A PIC controlled tail-light. My bike is not so fully equipped :)

I was a glazed-eyed teenager the last time somebody told me about RC  
networks, but I fooled with assembler for at least 15 years. It was a  
no brainer, those things are insane!

PG

On Tue, Sep 8, 2009 at 1:35 AM, Piers Goodhew<piers@...> wrote:
> With all this talk of "proper" solder masks, I thought I'd ask about
> some more rough-and-ready options.
>
> I've just successfully replaced the guts of my bike's tail light (with
> a PIC 12F6x and a lot of 0603 LEDs). Although it's sealed into a
> watertight box, I'm going to need to seal the copper against long term
> corrosion. It's a nice small board so I'm thinking of either painting
> it with urethane (e.g. varnish) or I thought it might be more durable
> but viable (given the smallness) to just paint it w/- araldite - a
> crude but effective "2-pack epoxy". That would write off a paintbrush,
> but be pretty tough.
>
> The reason for painting is to avoid the LEDs, or I'd just dip it.
>
> Anyone tried it? Am I crazy? etc?
>
> PG

Both will work.
(As in I have tried both, but only thin potting araldite not the thick glue).

There are also lotsa different spray cans with all sorts of conformal
coatings on the market.

I would avoid the LEDs.
Personally, If it was in a box, I'd either spray paint it with
sililicone conformal coating or dip it in a can of acrylic laquer. No
need to make it extra tough if it's in a box, unless you want to ride
that bike around the world. You'd never get through the araldite for
repairs or anything.

ST

I have used Clear Lacquer from spray can that you can get at most any Home Improvement Centers.

Ben