Chemistry and life.

Making printed-circuit boards. This is a chapter for beginners, too. A printed-circuit board is made of one-sided foil-clad glass-cloth laminate or hardened paper. Cut out a piece of the necessary size, cut out the picture of the printed-circuit board from the paper, glue the paper to the glass-cloth laminate and punch the holes. After the holes are punched and drilled, the board is to be cleaned by emery paper very smoothly. After that the paths are to be drawn.

I draw them with a usual sharpened match with common nail varnish. Do that accurately, without smearing.

Even the invisible layer of varnish perfectly protects copper from etching.

I know the following ways of etching printed-circuit boards:

• 1 part of 30% hydrogen peroxide, 1 part of hydrochloric acid and 3 parts of water.
• 2 parts of 16%-18% hydrogen peroxide, 1 part of hydrochloric acid and 2 parts of water.
• 1 glass of water, 4-6 pills of hydropyrite, 15-25 ml of hydrochloric acid.
• 50 ml of water, 2-3 pills of hydropyrite, 15 ml of hydrochloric acid.

I use the first recipe only. Etching takes place within a minute. Then wash it with water. Remove the remnants of varnish with acetone. After that clean it by emery paper.

Put in the scheme components and solder them.

Remember that not only bonding areas should be covered by tin, but the paths, too.

Attention! The signature on the Ê554ÑÀ3 microcircuit does not always correspond with the key on the chip! The first leg is always near the key!