diy prototype printed circuit board (pcb) manufacture
In the prototype phase, I made the circuit board myself because it was too expensive to design the circuit board professionally at one time.
I made the board myself using these basic techniques and was able to save a lot of cost while finally getting good final results.
The first phase of manufacturing is to design the board layout using CAD software packages.
I chose to use Eagle CAD, which has a free version that fits my needs and is very popular in the manufacturer community, and I have used it in the past, so its operation and feature set is very smooth.
I created a schematic of the base circuit and then routed it to the board file.
The next stage of the design process is to convert the circuit diagram into a circuit board layout that can be transmitted to a copper-clad glass circuit board.
The software allows me to see which pins each part needs to be connected to, which makes it easier to ensure the correct electrical connection.
To simplify the manufacturing process, I always try to make the board single sided, however, since the switch is on top of the board and the Arduino is on the bottom, I need to weld on both sides.
I could have used the SMD round-through switch, but I already have a bunch of straight-through hole switches that I want to use.
After the computer design phase, the padding, Vias, and top layer are exported from Eagle for single panel for dual panel.
The artwork is then mirrored and printed on a transparent acetate sheet;
I printed two copies so 2 sheets can be layered on top to eliminate the water leakage that could happen due to uneven coverage of toner.
I got the acetate tablets from WHSmiths in the UK and you can also buy them online.
I then cut the photosensitive copper wrap plate into just a good size larger than the acetate artwork, and then after removing the black protective film on the board, paste it with tape onto the anti-photoresist side of the board.
It is important to do so in a dark room to prevent unnecessary exposure.
The plate is then placed in the UV exposure unit for about 15 minutes to make the area without traces or pads sensitive.
After exposure, the Development Board is required, which is done using a strongly alkaline solution such as 1% Diluted sodium hydroxide.
However, I \'d better use Seno developer, which I purchased in an application bottle similar to a shoe oil container with a sponge pad at the bottom of the bottle.
This makes the area of the development board easier in a more localized way, as I find that using sodium hydroxide solution results in uneven results.
After successful development of the circuit board, the traces and pads become green and can then be used as etching resistant etch.
The green part will remain on the copper, and no green part will be etched, leaving only the glass fiber board.
The etching process is fairly simple but involves some hazardous chemicals and needs to be handled with care.
I used the transparent PCB etching agent from Mega Electronics, a relatively safe etching agent, but a little longer and stronger than the conventional choice of Iron Chloride.
However, the toxicity of this cleaner is much smaller and will not stain the clothes.
It is a powder that needs to be mixed with hot water to make a solution for etching the PC board.
Once a solution is formed, the board can be submerged and etchant will start removing copper from the UN
The masked part of the board.
It usually takes about 30 minutes for a small PCB to completely remove unwanted copper, and I find rubbing the board with an old toothbrush helps to speed up processing.
The final stage is to complete the circuit board by removing the etching anti-etch with ethanol or nail polish remover, which will then expose shiny copper that can be directly welded or done with a solder mask.
I bought a tube of green UV curing solder mask relatively cheaply online.
This requires a process similar to the photo etching method to apply the mask to the board.
Another product that can be used is liquid tin, which is coated with a very thin layer of tin on copper marks and pads, helping the welding process and stopping the oxidation of copper sheets.