www.delorie.com/pcb/spirals/   search  
Spirals Challenge

Adam Seychell suggested this pattern on the Homebrew_PCBs Yahoo! group as a true test for whether or not you can do a specific line/space size reliably. To test a given rule size, use the files below to etch a board. The board passes if each of the two independent spirals are contiguous (outer pad to corresponding inner pad < 4K ohms) and not touching each other (between outer pads > 1M ohms).

The PCB files are for the gEDA suite PCB editor. The gerbers are just for the one copper layer; use the corresponding drill file if you have a board professionally made. The PDFs are 1:1 but note that most postscript printers make the lines 1 pixel wider than spec.

Size PCB file Gerber Drill File PDF 1200dpi
PNG
Trace
Length
Trace
Ohms

Imperial

1 mil pcb gbr drl pdf png 1900 in1845 Ω
2 mil pcb gbr drl pdf png 949 in461 Ω
3 mil pcb gbr drl pdf png 632 in205 Ω
4 mil pcb gbr drl pdf png 469 in114 Ω
5 mil pcb gbr drl pdf png 379 in74 Ω
6 mil pcb gbr drl pdf png 316 in51 Ω
7 mil pcb gbr drl pdf png 269 in37 Ω
8 mil pcb gbr drl pdf png 234 in28 Ω
9 mil pcb gbr drl pdf png 203 in22 Ω
10 mil pcb gbr drl pdf png 189 in18 Ω
11 mil pcb gbr drl pdf png 172 in15 Ω
12 mil pcb gbr drl pdf png 152 in12 Ω
13 mil pcb gbr drl pdf png 141 in11 Ω
14 mil pcb gbr drl pdf png 128 in9 Ω
15 mil pcb gbr drl pdf png 126 in8 Ω

Metric

0.05 mm pcb gbr drl pdf png 24 m472 Ω
0.10 mm pcb gbr drl pdf png 12 m117 Ω
0.15 mm pcb gbr drl pdf png 7 m51 Ω
0.20 mm pcb gbr drl pdf png 5 m28 Ω
0.25 mm pcb gbr drl pdf png 4 m18 Ω
0.30 mm pcb gbr drl pdf png 3 m12 Ω
0.35 mm pcb gbr drl pdf png 3 m9 Ω

600 dpi

1.66 mil pcb gbr drl pdf png 1135 in664 Ω
3.33 mil pcb gbr drl pdf png 569 in166 Ω
5.00 mil pcb gbr drl pdf png 379 in74 Ω
6.67 mil pcb gbr drl pdf png 279 in41 Ω
8.33 mil pcb gbr drl pdf png 220 in26 Ω
10.0 mil pcb gbr drl pdf png 189 in18 Ω


  webmaster   donations   bookstore     delorie software   privacy  
  Copyright 2010   by DJ Delorie     Updated Sep 2010