How to make a PCB

From : http://hem.passagen.se/communication/pcb.html

This project will explain how you make your own PCB.
You will be amazed how easy it is and how good the result will be.
All you need is so get some basic stuff and time for experimenting.
All contribution to this page are most welcome!

Background
Many people ask me for PCB to my projects. I don't give out PCB because of two reasons.
1.) I reuse components and most likely you will find components but NOT with the same shape.
2.) Learn how to make PCB and you will be able to develop your own projects.
Some people like hole mounted components and some like surface mounted components.
Some day you want to stand on your own legs, so I will explain how easy it is to make your own boards.
right home in your kitchen.
Make sure your wife is out shopping or something..*smiling*

Measuring the components
I often reuse components I find in VCR, cordless phones and so. I use a measuring tool to measure the size of the components.
In the photo above I have found high precision crystal modules.

Design of the board layout using CAM350
There are many drawing program you can use for PCB and you can fin many free programs on the internet.
I have found a software called CAM350. It is not a complete development tool, it is just a basic drawing tool where you can draw lines, circles, square and make a component library yourself.

Download windows software cam350.zip (3.37Mb)
Click here to go to the software download page!

If you are rich you can buy advanced PCB software with autoroute and all ;-)
I like surface mounted components because they are smaller and you don't have to drill holes..lazy me!

Printing the negative plastic film

When the design is ready I just print it out on a laser printer.
I use transparent plastic film. The dark area will be cooper and the transparent area will be spacing. I always print out two films and tape them on top of each other.
In this way the dark area will be really black so no UV light can pass later.
You must be accurate when you place the two films on top of eachother. A small shift will give blurry lines of the board.
I place the films against a window, since a window is flat and you can see the light come through the films.

When It looks good I place tape at three sides to fix the two films together.

Glasses and weights

At the bottom I have a glass so the board will lay on a flat surface. (difficult to see)
You can use any ordinary glass. Enough UV will still pass through the glass.
Then comes the board. On to the board are the two films and finally on top of that I have placed another glass.

(Difficult to see in this figure, but there is two glasses and between them is the board and film.)

To the left and right you can find two weights. I have placed them there to press on the glasses so the film will be close to the board.

This is important because if you don't have glasses pressing the film, you can easy get a small space between the film and the board and that will make the lines blurry!

Preparing the UV lamp

The PCB I use have been pre-sprayed with a UV sensitive layer of color.
If you have difficult to find thoose PCB, you can find them at my component page.
Click here to go to my component page.
So where can you find UV light.
I went to a second hand store and found an old UV-light from the 70:th used for sun tanning.

This lamp gives UV-A, B,C and I think even some X-RAY....*smiling*
I am sure any UV lamp will do the job for you.

The photo show you how I have placed the lamp in my kitchen.
Under the lamp is the bottom glass I told you before.

The light is really strong and I recommend sunglasses because UV light can damage your eyes.

Exposing/developing the board

Here I have placed the board with the 2 glasses under the UV-lamp.
Areas of the PCB exposed to the UV light (through the film) are turned into a protective plastic film. I have experimented with different timing and I have noticed that 3-4 minutes will give good results.
If you overexpose the board, the light will penetrate the black area and give bad results.
Don't touch the board during the exposing.

After 3-4 minutes I turn off the UV-lamp and remove the board to let it cool down.
It needs to cool down because it is quit hot (30-40 degree Celcius) and if you put a hot board into the developing liquid (water solution of NaOH) the reaction will got to fast and you loose the lines.
So, let the board cool down (shake it) and then put into the developing liquid.

When you buy the NaOH powder, you can read the label how much mixing water you need.
If you think the developing reaction goes to slow (not at all) try to warm the solution just a little.
Also here you need to experiment a bit.
When I mix the NaOH I get about 2 litre. Then I use some "dummy" boards to test the solution.
When you test the "dummy" boards make sure you expose it to UV light as it would be a real board.
During the developing phase you will see the pattern from the films grow on the board.
For me the developing phase takes about 1-2 minute then I shower the board with fresh water to remove NaOH remains.

Etch the board

There are several different solution used for etching. I advice you to buy a etch kit with powder.
The etching process will be fastest when the solution is warm.
I put the board into a plastic jar filled with etch solution.
I then put the jar into a pan with water. I warm the pan on the stove until the water almost boils.
The heat will transfer into the jar and the etching process will work great.
I move (shake) the jar to speed up the etching time.

The etching time is about 5-10 minutes.

Finnished board

Here you can see the finished circuit boards with edges and lines sharp as razorblade.
All you need to do now is to clean the board with Acetone to remove the protective plastic film.

Final word
A good board will improve the quality of your projects,
Specially if you are into RF homebrewing.
Now you know how to make PCB of your own.
You need to buy some stuff, but I assure you the result will be great!
Click here to see photo and read how to solder SOIC and smd components.

Many people has written to me and asked about the UV lamp.
I advice you to go to a electronic shop and ask for UV light (tube) and they will help you.
This is what Rafael Santos from Portugal did and I want to show his great UV-box.

Rafael say "They told me that the lamp TL 05 is great to do PCB's ,
this lamp is used in stores to kill fly's, they go against the lamp and bzzz....."
Watch and enjoy...*smiling*
I think his work will inspire all of you to build your own UV box.