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professional home brew pcb: creating a solder mask using uv curable paint

by:Tuowei     2019-09-04
I noticed that on ebay you can buy UV curing paint and make a welding mask on the pcb etched in your home, but the instructions that came with it are terrible.
On the description of the auction and the paper that eventually came with it, all it says is. -
Apply paint on PCB
Spread it on the PCB with a covered transparent mask film-
Exposure under ultraviolet light (or sun )
Minutes-
Washing off excess paint with gasoline or oil-based solvents sounds a bit sparse and inaccurate, so after some investigation and experiments I came up with this guide.
You need to do this :-
UV curing PCB ink-Ebay-
Foam brush or roller (
You will use less paint with foam brush)-Dollar shop-
Inket or laser rays-
Office supplies store
Inkjet or laser printerOld toothbrush-
Mineral radish-Hardware store-The Sun-
A piece of glass, you need to find your own position in direct sunlight, under the faint fluro bulb in the room.
First of all, squeeze out a little paint along the top edge of the PCB and scrape it off with a foam brush, just like you bought from a craft store or a dollar store, try to get even insurance.
You don\'t need too many things to cover, too many things will greatly increase the drying time.
Before you get an even light coating on the board, work the paint before and after. All your tracks should have a green one (
Or any color you are using)tinge to them.
Now leave the board in a dark place to dry for hours.
I put mine in a sealed carton to make sure it is not exposed.
You now need to print the welding mask that will cover the circuit board and protect the pads you wish to weld from hardening in the sun.
If you use Fritzing to design your PCB, then when you export it, it creates a PDF of the welding mask that you can also print.
If you print your mask using a laser printer, then make sure you use the highest quality possible so that it has the most toner on it, creating an effective block for UV rays from the sun.
Reduce the mask to the same size as the PCB.
Once your PCB is dry, it\'s time to put your mask on your board and rinse it down with a piece of glass.
This will avoid a shadow on the board to protect what you are not going to do.
Place in direct sunlight for about 30 minutes.
Now, the UV should have hardened all areas except the area protected by the mask, put it inside, remove the mask, and gently scrub the mat with a radish with a toothbrush.
Areas that are not exposed should be washed away.
Rinse the plate in the water to remove any excess radish.
It should be welded now.
Your pcb should now have a nice green soldering mask to protect your circuit. I found that I could also use a foam brush for some strokes, and it may be necessary to wear several coats in order to get a uniform covering.
I\'m not sure how this will affect UV exposure, though.
The ink I purchased has matte finish, which is good from a functional point of view, but to improve the appearance of the cardboard, it may be worth it to apply a transparent polyurethane after the welding is completed.
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