As an enthusiastic electronics hobby fan I was always fascinated by the fact that it is actually possible to make an almost professional looking Printed Circuit Board (PCB) at home.
My eager for producing my PCB's at home rather than using the good old wire-wrap prototyping method gets even stronger as the years goes by and the availability of through hole packages (for modern devices) is getting lower and lower. When thinking of a new design, one has much more devices to select if SMT technology is acceptable. That is a very strong motivation to learn about making your own SMT PCB at home.
Lets brake the previous sentence into smaller pieces now.
A finished design should look like a graphical representation of the traces that should reside on the finished board. The image must be mirrored because of the way we are going to use it later in the process. Now, Glossy paper is a general term for a more confusing definition like 'Some paper used by ink jet printers for photo printing'. Just in case you didn't know, Not all photo papers were born equal. Finding the right paper for this job may be tedious. The first paper I used could not be peeled off the PCB at the end of the process and I had to throw it away. The next paper I found was a hit. It peels easily and leaves a clean print of the traces over the bare copper. I will discuss this peeling issue later in the process. Remember that you may try few photo papers before you find the 'one'. Don't get give up right away. Luckily enough, there are special Toner Transfer Papers designed exactly for this purpose.
Now that we have a printed version of our PCB in hand, we would cut the paper to the outlines of our board and leave few more millimeters of paper on the edges of the board. This leftover outside the outlines of the board will be used later as a grip point for peeling the paper.
This is the part where get our hands dirty by doing some craft work.
A PCB starts as a laminate of a thin copper layer over a glass epoxy substrate (also called FR4 laminate). Laminates can be usually found where you'd buy your electronic components. There are two types of laminates for the home user. Single sided and Dual sided. usually 1mm to 2mm thick. Single sided means that there is copper only on one side of the laminate. Dual means there is copper on both sides of the laminate. This paper focuses on single sided PCB's so single sided laminate is good enough. Single sided circuits can be made of single or dual sided laminates because either way any unwanted copper is etched away.
Cutting the laminate to the circuit size is done in two phases. First, you mark the height of your circuit across the laminate using a sharp knife and a ruler. The deeper the marking the easiest it is going to be. After marking the line, you should align the straight line with an edge of a table and place a ruler above the laminate. Applying pressure on the laminate should brake it across the marking leaving a nice straight edge. Now, the width of the circuit should be marked and cut at the same way.
Now that we have the laminate cut to the size, we should prepare it for the toner transfer process. Using the finest sandpaper (wet paper) the copper should be sanded evenly until the copper is clean and shiny leaving microscopic scratches on the copper surface. These microscopic scratches are best as gripping points for the sticking of toner to the copper.
After sanding the copper it is important to wash the laminate with soap. Using kitchen dishes soap would be best. This washing is intended to remove any grease leftovers (fingerprints are greasy too). Grease leftovers would prevent proper sticking of the toner to the copper. Avoid touching the copper after washing it because it should be kept grease free (fingerprints are greasy). Finally the laminate should be dried using a paper towel.