02-08-2011, 03:43 PM
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Most electronic hobbyist did not know how to make printed circuit board for their small circuits. In this article I will tell you how to make a printed circuit board easily. For making printed circuit board (PCB) for small circuits you need clad board, ferric chloride (FeCl2), OHP marker pen, ect.
First of all prepare the layout of the circuit using any PCB schematic drawing software (e.g. - Dip Trace, Express PCB, Eagle, PSpice, ect). Print the layout on an ordinary paper.
After preparing the layout, cut the clad board according to the size of your layout. Transform the layout to the clad board. This can be done by several methods. One method is by drawing the circuit layout exactly on clad board using an OHP marker. This is the simplest method for small circuits. For this, draw the circuit layout on clad board using carbon paper and pencil. Draw the layout using an OHP marker above the sketch layout. Ensure that hole positions are at right positions.
Second method is by using an electric iron (toner transformation method). For this you need the mirror image of the circuit layout. Then print this mirror image using a laser printer (set the toner deposit to high i.e. Image will look dark). Place the image on the surface of clad board upside down. Heat the electric iron and place the iron on the paper having image which is now on the surface of the clad board. Keep the iron for some seconds. Do not heat excessively. Then the toners on the image get transferred to the clad board. After this put the clad board along with the sticky paper on hot water and kept for a long time. The paper becomes lousy. Now remove the paper from the clad board carefully. Do not remove the sticked toner. Now you will get the layout on the clad board. The next step is the process of removing copper which are not covered by the layout.
For etching process we need ferric chloride (Fe Cl2) solution. About 100 ml of tap water should be heated to 85 degree celcious and 30-50 grams of ferric chloride added to it. The mixture should be thoroughly stirred, and a few drops of hydrochloric acid (HCL) may be added optionally to speed up the process.
The board with its copper side facing upwards, should be placed in a flat bottomed plastic tray and the aqueous solution of ferric chloride poured in. The etching processes will take 25-60 minutes to complete, depending upon the size of the PCB. After etching the board should be clearly visible. If not allow it to stand in the solution for some more time. The paint (toner, OHP marking) should be removed with the help of alcohol or petrol. The etching solution may be preserved for later use until its color turns green.
After the etching is complete, holes of suitable diameter should be drilled using a power or hand drill. 1mm bit should be used for IC holes, 1.25mm for resistors and 105mm for diodes, 3mm or 5mm for mounting nuts and 8mm for potentiometers, switches, ect.
Now the PCB should be scrubbled clean until a shiny finish is obtained. The PCB may be tin-plated using an ordinary 35W soldering rod along with solder core.
Note: - Before beginning you should roughly clean the surface of the clad board.
You can also draw the circuit using paints and brushes.
If you are not tinning, make a varnish coat over the PCB after colliding components.
