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Photo Etching

Description

I decided it was time I stopped messing about with strip-board and start making some PCBs. Most higher end MCUs and other componenets are only available in surface mount packages, and so PCBs are the only option.

Specifcation

Main Features

PCB: FR4 postivtve photo board

UV light:: 2 x 8W 12inch tubes

Developer: Any NaOH free developer!!

Etchant: Ferric Chloride

Make high quality fine pitch PCBs

How it works

I will quickly outline my method of making PCBs. When you first start you will screw up quick a few, so practice on small sections of board.

First you need to design the circuit layout. There are many software packages which you can use. I started out using the 'express PCB' software which is free, however it has been designed so you cannot easily make a template from you design...it can be done by printing the design to a primter 'image' files, then re-saving, editing, then resizing....a real pain in the arse. I recomend somthing like ARES from http://www.labcenter.co.uk/......anyway, you need to be able to print out copper track layout.
Now you need to print out your design onto transparent paper or plastic. There are a few options, I'v tried tracing paper and OHP transparancy. You will need to experiment, but at the moment im finding the OHP plastic is working very well, Im using an Epson printer, set it to 'Photo paper' or 'Photo glossy film' NOT the specific Transparacy option which it has, as the colour will not be dark enough. Oh yeah, you need to print postive, ie black where copper should be.
Now you need to expose the PCB......I will finish this later, If anyone is acctualy reading this and wants to know the rest, then remind me and email me on eb1810@bris.ac.uk!

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