During PCB fabrication, a Printed Circuit Board is etched using acid to remove all the unwanted copper from the laminate. A temporary mask is applied to protect all the parts of the laminate from acid. Remember that there may be risks in the PCB fabrication process because the materials used can be volatile or toxic. Properly dispose of chemicals by placing them in appropriate containers. Use all the protective equipment needed like gloves and masks, and also, familiarize yourself with all the tools and materials needed for PCB fabrication.
Most importantly though, you need to know the steps involved in the etching process by heart.
1.In doing PCB fabrication, be sure to work in a ventilated area before mixing the chemicals. Design a layout for the circuit board. Print the layout on specialty paperusing a laser printer. Some prefer to use glossy paper. Using glossy paper will make the toner adhere to the plate without using too much equipment. Keep the pages as flat as possible and try not to accidentally put oil on them so that a flawless product can be made.
2.Use a non-metal basin and check if the basin you will use can withstand the effect of the acid that will be used for etching. Carefully clean the residual dust from the substrate that you will be using. Use a soft sponge and a slightly damp paper towel.
3.Position the board on a flat surface and use a hot flat iron to make the print adhere to the board. Align the print properly to the board and as much as possible, do not allow it to move. Push the hot iron down for about 1-2 minutes. After that, move the iron around the board for about 4-5 minutes. Let it cool down before you move it about. Put the board in cold water and let it soak for 5-7 minutes. Peel the print off the board and if it still does not come off, let it soak for another 3 minutes.
4.Immerse the board in acid to clean the remaining copper. The usual recipe is two parts of hydrogen peroxide and one part hydrochloric acid. The acid should be mixed with water and not the other way around. After they are mixed, it can be very irritating to the skin and may produce harmful fumes. Mix just enough to submerge the circuit board. After the substrate has been submerged, the acid will react and the solution will get warmer. It will start to produce more fumes. Do this process for about 13-15 minutes. Stir the solution and check if it begins to take on a green tint. This means that the copper is beginning to clear up from the board.
5.If the copper is dissolved, wash the board with running water for about 1-2 minutes. Use a paper towel or dry rag to remove the water from the board. Remember to use gloves when handling the board.
6.When disposing the etching solution, dilute it first in water to make it less hazardous. Dispose it in the appropriate chemical waste facility. The etching solution is very harmful especially if flushed down the drain. It can kill marine organisms, even if only a very small amount is ingested. It can also damage pipes, and that is why it is necessary to take the precautions mentioned before.
7.To completely clean the board, mix rubbing alcohol and acetone at one is to one ratio. Use a paper towel to wipe the black print off the board. Revealed under it is the etched mark of the copper on your board.
Etching, and fabrication as a whole, is a complex procedure. So, never rush into things for the sake of quality and safety.
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