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Please note that this chapter is in outline form and will be fleshed out later. Use it to guide you through your own research.
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| Electronic equipment before printed circuit boards |
The fact that printed circuit boards make building electronic equipment easier goes without saying.
Starts with copper-clad board
A fiberglass or paper-phenolic resin board with a thick layer of copper bonded to one side
Materials available at electronics stores (i.e., Frys)
Clean copper
Steel wool or sponge with scouring powder
Draw circuit with acid-resistant pen
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| Hand-drawn PCB ready to etch |
Special pens are available, but a Sharpie® works well
Draw twice (two coats of ink)
Etch away unwanted copper
Ferric Chloride or other etching solution
Clean off ink
Solvent or scrub with steel wool or scouring powder
Drill holes
Drill may tend to tear copper off board
Drill before etching
Use drill holes as guide to draw traces
Use carbide-tipped drills
Expensive and very brittle. Tend to break if any side pressure is put on them
Layout aided by software
Printed on plain paper with laser printer
Toner transferred from paper to copper clad board with iron or hot press
Paper removed by rubbing under water
Etched as in hand method
Drill holes (predrilling is problematic because it is difficult to align paper with drill holes [alignment holes in paper help])
Layout aided by software
Negative printed on laser printer
Copper clad board is coated with photo-restive material
Photo restive material hardens when exposed to light (usually UV)
Solvent washes away unhardened material
Copper clad board exposed through negative and developed with solvent
Etches as in hand method
Drill holes (predrilled holes help alignment)
Predrilling board helps alignment whether making by hand or mass producing
Jumpers between sides where necessary.
DIY through-plating of holes is possible but may be daunting (https://blog.honzamrazek.cz/2017/10/diy-through-hole-plating-of-pcbs/)
Hazardous waste. Disposal depends on jurisdiction.
Improves with use
Predrilling holes causes some copper to be etched away around drill hole. Touching up bare copper with Sharpie® will help.
Overly-hot soldering irons can remove copper from board
Traces may form hairline cracks without board cracking. Most common with paper-phenolic resin boards.
May be one-sided, two-sided or multi-layered
When repairing or modifying multi-layer boards and drilling through board, be careful not to damage internal traces
Through-plated holes
Jumpers not required between sides
Solder mask
Usually green or orangeish
Used for mass soldering (wave soldering). Allows solder to only reach pads.
Provides some protection to traces when board is being handled
Must scrape away when making repairs or modification.
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