Page 102 - CNC Robotics

Chapter 3 / Making the Printed Circuit Board

Etching

W hen you are happy w ith the toner resist, proceed to etch the
boards. Ferric chloride will remove all the unprotected copper on
the board. WARNING: It will also bu rn your skin, so make sure
you use gloves, eye protecti on, and a respirato r w hen working
w ith this etchi ng chem istry. Try to maintain a good wo rking tem-
peratu re with the setup (see Figure 3.24). Don't let th e tempe ra-
ture of the working solution go high er than 40 degrees Celsius (104
degrees Fahrenheit). At temperat ures higher than th at, it will give
off some nasty and dangerous fum es.

Figure 3.24
Etching setup .

I like to use a floating thermometer to keep an eye on the temper-
ature, but any thermometer shou ld work. Keep checking the board
in the ferric chlo ride solution (see Fig ures 3.25 and 3.26).

The amount of time required to etch the board w ill vary w ith the
temp erature of th e ferric chloride and how many times the etching
solu tion has been used. W hen th e board looks like Figu re 3.26,
it 's done. Rinse the board in clean water to stop the etching (see
Figure 3.27).

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