How to DIY PCB and soldering

PCB also known as printed circuit board, is an important electronic component, it is the support of other electronic components, provider electrical connections for electronic components. Because it is made from printing technology, it is called "print" circuit board. We write this article to help electrical fans to DIY their own PCB, no need to always use breadboard to test their design or find PCB manufacturer for prototyping PCB.

Step 1. Print PCB design

Design the circuit to be placed onto the board using PCB design software. Plenty of Software you can use like Protel, OrCAD, PowerPCB, Cadence,Mentor Graphices etc.

Print the circuit design onto sheets of transparent ink-jet compatible paper. Set your printer for transparency printing, using the highest quality print settings. For monochrome printers, set the intensity and contrast settings as high as possible, in order to use as much black ink as the printer will allow during printing. Make sure that you print the design onto the slightly sticky side of the transparencies.

Trim the transparencies around the printed design and tape the transparencies to a thin glass panel like that found in a photo frame, using transparent tape.

Remove the protective paper cover from the photo PCB and place the PCB with the photo-resistant layer side to the transparency. The setup should be the glass piece, followed by the transparency, then PCB board, with the design centered on the board.

Step 2. Exposing PCB

Place the PCB into the fluorescent lamp, with the copper side of the board facing the fluorescent lamp.

I use simple fluorescent lamp. All fluorescent lamps have some UV specter. It is enough to expose the PCB. The exposure will transfer the circuit design to the copper surface, hardening the photo-resist layer in the needed design on the board.

Other method is use UV bulbs, The UV exposure unit can be purchased from most scientific supply stores, or be built using a UV lamp and an enclosed space. If using a DIY exposure method, you will have to experiment with exposure tiles to determine the best results.

Step 3. Prepare developer solution

Prepare the developer solution in a bowl large enough to hold the PCB board, following the solution manufacturer's instructions on mixing.

Step 4. Etching PCB

Remove the PCB board from the exposure unit and remove the glass and transparencies. Place the board into the developer and use a foam brush to remove the green photo resist layer from the board. The unhardened resist should come off quickly in one to two minutes. Be careful not to remove the hardened resist. Place the board in water to neutralize the developer.

Etching the circuit design into the board by removing all of the copper from the board, except that of your design. Remove the board from the solution and wash away the solution using running water.

I don’t use ferric chloride (it has orange color). I use Copper (II) sulfate + Salt + Water (it has green...blue color, it depend from concentration of copper).
The ferric chloride is difficult to clean up. Stains on the furniture remain forever. Copper (II) sulfate is less aggressive, but it clean up easier. For home prototyping, I think, Copper (II) sulfate is best choice.

Step 5. Drill holes in to PCB

Drill holes according to drill layer of PCB Design, don’t shake you hands too much, if you can find something to fix PCB, it is better. The holes can not be too small or too big, because drill bit at your hand is normal size.

Step 6. Solder Components by hand

First coat clean pads with solder flux, and then use the electric iron add to pads with a thin layer of solder, the components are placed up aligned diagonally fixed on the PADs. Final inspection, re-solder the too loose points. Electric iron soldering temperature should be moderate, generally around 400 degrees. Inspection Method: First of all visual, then check each for loose pins with a pointed thing, the last you can use multimeter measurements.