Free Manual on Etching A Printed Circuit Board

                              With the Toner Transfer Method
When working with electronics, breadboards are a cheap way to put together circuits. Having professional Printed Circuit Boards made can be very expensive in small quantities, but the results not only make projects easier to construct but also make them look fantastic. While the cost of production is a great deterrent, for less then $20 it is possible to etch your own PCB.

There are two ways to etch a PCB:

1. The Toner Transfer method, and

2. The Photo Resist method. This article will examine the former method using common household items.

Before you start you will need the following:

·   Access to a Laser printer.
·   A sheet of photo gloss paper.
·   A fibre glass copper coated board.
·   Ammonium Pursulphate.
·   A cloths iron.
·   Plastic containers.
·   0.8mm 1.0mm and 1.2mm drill bits and a drill.
·   Pliers
·   A hacksaw
·   Acetone or mentholated spirits.
·   Some Fine grit sandpaper or a scotchbrite pad.

The following optional parts will also help improve the results:
·   A fine artwork knife, or scalpel.
·   A etch resistant touch-up marker.
·   A kettle.
·   A metal file
·   Some kind of small rotary tool like a Dremel instead of a drill.
·   A toothbrush
·   PCB solder-through lacquer.

* Ferric Chloride can also be used. For guides on etching with Ferric Chloride select the link at the bottom of this article.

PREPARING THE PCB DESIGN
There are many packages such as Protel, Eagle, or express PCB to name a few, which allow you to design your own PCBs. Ultimately the choice of software is unimportant as long as you end up with a black and white image of the traces which you want to transfer to the copper board.
Because the process of transferring the toner to the paper flips the image which has been printed, the orientation needs to be carefully considered. When putting traces on the bottom of the PCB the printout should be normally oriented as if looking through the board form the top as it will be flipped to the bottom during the transfer process. Traces on the top of the PCB require the image to be mirrored to appear in the correct orientation.
In this guide I will etch a simple stepped-on / stepped-off circuit containing a 12v regulator, a relay, and a pair of 4049 CMOS hex inverters. The small traces on this board have a width of 20mils (approx 0.6mm), and the pads have a trace width of 11mils. The smallest gap between traces is 13mils.

PRINTING
The toner transfer method relies on the fact that toner, being plastic based, will form a protective coating on the copper which is resistant to the corrosion of the etching agent. It is therefore important that the toner coverage is consistent and will not stick to the paper more then the copper board.
The choice of paper is critical to the entire process. Professional Press n Peel films can be used but are usually very expensive costing several naira per sheet. Instead inexpensive Inkjet paper can be used too.
I personally use Ink jet “Glossy Photo Paper”  as I do not have access to a Staples store.
If you are choosing your own paper there are several important things to remember:
1.   The paper will be heated to really high temperatures. Papers like Kodak Glossy Photo Paper or Canon Photo Paper Pro have a plastic film on the back which will curl up and melt when heated potentially damaging the cloths iron or even the fuser in the laser printer.
2.   The paper must provide consistent toner coverage with no visible blemishes in the final print. Any blemishes in the toner will cause etchant to seep through and corrode the copper underneath.
3.   Finally the toner must stick to the paper hard enough not to fall off during handling, yet not stick to the paper when it is being peeled off the copper board.
Once the paper has been chosen print the image as dark as possible on the glossy side of the paper to provide as much toner as possible.

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CALL: LEKAN ON: 07037914178,OR 01-4748802 FOR PRACTICAL