how to etch a circuit board

I noticed at the local elecronics shop sheets of copper with some type of etching pen. How is this system used to make a circuit board ?

It must be "etch resistant pen". It is a very old inaccurate and crude method in which you draw the layout using this pen and then etch the unwanted copper out using etching chemicals like ferric chloride.

Now a days most people use transfer method using photo-paper or press-n-peel film on which you take printout of your layout using laser printer and transfer it onto copper-clad using cloth-iron and then etch the board.

Thanks for that explanation, Ill uswe the later method when i get around to making my own circuit boards!

On a different note I have always wondered why they call breadboards , breadboards. Apparently in the 'olden days' , folks hammered nails into wood boards and connected up their circuits like that. Not sure where the 'Bread' part applies, maybe they used to pinch their mums bread cutting boards to do the job

ps. do you have to use a laser printer ? Is inkjet suitable ?

one of the best and reliable way of etching a circuit board is to use the presensitized board. What you will do is to have your layout on a white paper and then expose ot onto the presensetized board using florescnet light for a period of time. then soak that on an coastic soda then you will have a perfect etch on your pcb.

expelleior said:

On a different note I have always wondered why they call breadboards , breadboards. Apparently in the 'olden days' , folks hammered nails into wood boards and connected up their circuits like that. Not sure where the 'Bread' part applies, maybe they used to pinch their mums bread cutting boards to do the job

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an explanation in wikipedia: https://en.wikipedia.org/wiki/Breadboard

The term breadboard is derived from an early form of point-to-point construction: in particular, the practice of constructing simple circuits (usually using valves/tubes) on a convenient wooden base, similar to a cutting board like the kind used for slicing bread with a knife.[1].

[1] Paul Horowitz and Winfield Hill (1989). The Art of Electronics (Second edition ed.). Cambridge University Press. ISBN 9780521370950.

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laiza said:

one of the best and reliable way of etching a circuit board is to use the presensitized board. What you will do is to have your layout on a white paper and then expose ot onto the presensetized board using florescnet light for a period of time. then soak that on an coastic soda then you will have a perfect etch on your pcb.

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Do i printout the circuit on standard paper, face it down on the board and then use floresent light then soak ?

Yes, that's the idea. First you buy in any electronic store a "presensetized Board" its like 4x3 inch board. then you should have a costic soda and another liquid (i forgot the name but it is the one used in etching in ordinary board to form a copper etch). Then print your layout in a bond paper. Cut your board and place the layout and expose it to flourescent light. instructions are written on the "presensetized board". everything is perfect as long as you follow the instructions. We had already used it already.

For less complicated boards (non-SMD, 0.5+mm trace widths), I print (laser printer, of course) the layout on thin (semi-gloss) paper from a magazine, for example. Use an iron to stick it onto a piece of typical piece of vitroplast or pertinax. Then dissolve the paper in water, which only leaves the 'black' bits - ie. tracing.

Instead of using ferric chloride, I use 16~18% Hydrochloric Acid mixed with 30% Hydrogen peroxide in an approximate 15:1 ratio (in favor of acid). It's cheap and easy to buy (both acid and peroxide are less than 2$ a liter, and you can do a large number of boards with it). You don't have worry about disposing it, unlike Ferric Chloride, if I read correctly.

You don't have worry about disposing it, unlike Ferric Chloride

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Generally you have to worry about disposing heavy metal compounds as used etch solution containing copper. It's a strong biozide, e.g. causing difficulties in a sewage plant.

The activated hydrochloric acid is a powerful etch compound, but it's producing an unhealthy aerosol and shouldn't be used without good ventilation or better a laboratory fume hood. And not processed without rubber gloves and protection glasses.