WEEK 24
5 week to
goooo.....!!!
In this week, the
objective that need to be achieved in this week is to make sure that the
etching process had been done. The first step in this week and to complete the
first objective in this week is to produced the PCB board and the etching
process must be done. Below picture shown the step by step in developing the
PCB
Step 1: Prepare a
layout of the circuit on any commonly used PCB designing software. A layout is
a design which interconnects the components according to the schematic diagram
(circuit diagram). Take a mirror image print of the layout on the OHP sheet
using a laser printer. Make sure that the design is correct with proper placement
of the components
Step 2: Cut the
copper board according to the size of layout. A copper board is the base of a
PCB, it can be single layer, double layer or multi layer board. Single layer
copper board has copper on one side of the PCB, they are used to make single
layer PCBs, it is widely used by hobbyist or in the small circuits. A double
layer copper board consists of copper on both the sides of the PCB. These
boards are generally used by the industries. A multilayer board has multiple
layers of copper; they are quite costly and mainly used for complex circuitries
like mother board of PC.
Step 3: Rub the
copper side of PCB using steel wool. This removes the top oxide layer of copper
as well as the photo resists layer if any.
Step 4: Put a
white paper on the OHP sheet and start ironing. The heat applied by the
electric iron causes the ink of the traces on the OHP sheet to stick on the
copper plate exactly in the same way it is printed on the OHP sheet. This means
that the copper sheet will now have the layout of the PCB printed on it. Allow
the PCB plate to cool down and slowly remove the OHP sheet. Since it is manual
process it may happen that the layout doesn’t comes properly on PCB or some of
the tracks are broken in between. Use the permanent marker and complete the
tracks properly.
Step 5: Take a
plastic box and fill it up with some water. Dissolve 2-3 tea spoon of ferric
chloride power in the water. Dip the PCB into the Etching solution (Ferric
chloride solution, Fecl3) for approximately 30 mins. The Fecl3 reacts with the
unmasked copper and removes the unwanted copper from the PCB. This process is
called as Etching
Step 6: Take out
the PCB wash it in cold water and remove the ink. The remaining area which has
not been
etched is the conductive copper tracks which connect the components as per the
circuit diagram.
Step 8: Once all the copper is
gone rinse it in the water bath, let it dry and use rubbing alcohol to whip off
the ink transfered onto the PCB and PCB already DONE!!
