how design a PCB board in own purpose, then how to handle the board in running time

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  • Finger POINTengg says:

    Design of PCB:
    This can be done usually by converting circuit diagram into PCB layout using PCB layout software. Software like Cadsoft Eagle ,PCBWizard etc.
    The steps to be followed are:
    1.Take a Mirror printout of circuit board layout using laser printer and A4 photo paper/glossy paper.
    2. Cut the copper plate for the circuit. Next, rub the copper side of the PCB using steel wool or abrasive sponge scrubs which removes the top oxide layer of copper as well as the photoresist layer. Sanded surfaces also allow the image from the paper to stick better.
    3. Transfer PCB print into copper plate using any of 2 methods.
     1.Iron on Glossy Paper Method (For Complex Circuits)
    Transfer the printed image (taken from a laser printer) from the photo paper to the board. Make sure to flip top layer horizontally. Put the copper surface of the board on the printed layout. Ensure that the board is aligned correctly along the borders of the printed layout and use tape to hold the board and the printed paper in the correct position.
    2. Circuit by Hand on PCB (For Simple and Small Circuits)
    draw a basic sketch on the copper plate with a pencil. Once your sketch looks good, trace over it with a permanent black marker.
    4. Iron the Circuit from the Paper onto the PCB Plate
    ▷ After printing on glossy paper, we iron it image side down to the copper side, then heat up the electric iron to the maximum temperature.
    ▷ Put the board and photo paper arrangement on a clean wooden table (covered with a table cloth) with the back of the photo paper facing you.
    ▷ Using pliers or a spatula, hold one end and keep it steady. Then put the hot iron on the other end for about 10 seconds. Now, iron the photo paper all along using the tip while applying a little pressure for about 5 to 15 mins.
    ▷ Pay attention to the edges of the board – you need to apply pressure and do the ironing slowly.
    ▷ Doing a long hard press seems to work better than moving the iron around.
    ▷ The heat from the iron transfers the ink printed on the glossy paper to the copper plate.

    After ironing, place the printed plate lukewarm water for about  10 minutes. The paper will dissolve, then you can remove the paper gently. Remove the paper by peeling it from a low angle.
    5.Etch the plate.
    ▷ First, put on rubber or plastic gloves.
    ▷ Place some newspaper on the bottom so the etching solution does not spoil your floor.
    ▷ Take a plastic box and fill it up with some water.
    ▷ Dissolve 2-3 teaspoons of ferric chloride power in the water.
    ▷ Dip the PCB into the etching solution (Ferric chloride solution, FeCl3) for approximately 30 minutes.
    ▷ The FeCl3 reacts with the unmasked copper and removes the unwanted copper from the PCB.
    ▷ This process is called Etching. Use pliers to take out the PCB and check if the entire unmasked area has been etched or not. In case it is not etched, leave it in the solution for some more time.
    Gently move the plastic box to and fro so the etching solution reacts with the exposed copper. The reaction is given as:Cu + FeCl3 = CuCl3 + FeAfter every two minutes, check to see if all the copper has been removed. If it hasn’t, then place it back in the solution and wait.
    6. Cleaning, Disposal, and the Final Touches for the Circuit Board
    ▷ Be careful while disposal of the etching solution because it is toxic in nature.
    ▷ A few drops of thinner (nail polish remover works well) on a pinch of cotton wool will remove completely the toner/ink on the plate, exposing the copper surface.
    ▷ Rinse carefully and dry with a clean cloth or kitchen paper. Trim to final size and smoothen edges with sandpaper.

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