Since I don't run a labratory and I have a standard printer capable of printing 600 DPI, I'm trying to make a small circuit board but I'm wondering, whats the closest I should place the pins of a DIP IC to the edge of a circuit board?

My normal track settings are 0.3mm thickness, 0.3mm minimum spacing between everything.

I am at a hobbyist/amateurish level so I don't want to screw up my circuit only because an IC is too far to the edge.

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    \$\begingroup\$ If you're cutting the board yourself you can make it however close you like. \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 13 '16 at 0:05
  • \$\begingroup\$ Are you making single or double sided boards? Are you using photoresist or some other technique? \$\endgroup\$ – gbulmer Oct 13 '16 at 0:33
  • \$\begingroup\$ I'm using the photo-resist method and single sided board and I print my masks on transparencies and I have to line up two copies of the same mask to get a dark image. \$\endgroup\$ – user116345 Oct 13 '16 at 0:52

Depending on your etching setup, 0.3mm may be too small, and you might find you're etching away part of your tracks or you might find shorts between them. Home-etched boards generally require a lot more space to prevent these problems, I would probably shoot for around 0.5mm minimum trace width/spacing.

For my professionally made boards I generally aim for 20 mil (~0.5mm) minimum distance between any copper or pads and the board edge. For hand-etched boards I would probably aim for about twice that (~1mm) minimum from the board edge. This will minimize the chances of problems.

It does very much rely on your experience and confidence level, though. I suggest giving it plenty of space to begin with, and as you make more boards and you find the tolerance is pretty tight, you can reduce the clearance and trace widths as needed. It's entirely up to you, but the numbers I offered should at least provide a jumping off point.

  • \$\begingroup\$ I just tried a photo-resist PCB design with 0.2mm track width and 0.2mm track spacing and some lines washed away in the developer. I seem to have more successful results with 0.3mm width and 0.3mm spacing. \$\endgroup\$ – user116345 Oct 13 '16 at 1:24
  • \$\begingroup\$ @Mike - I've done 10mil (~0.25mm) track and space but using 'proper' film designed for a laser-printer, so only one mask layer. I wouldn't be surprised if you could do 0.3mm, but getting alignment and not 'shadow' with two masks might be more of a problem than the etching fine tracks. We took care to get good calibration of exposure time and etching time. We used 'persulphate' (not ferric chloride) \$\endgroup\$ – gbulmer Oct 13 '16 at 1:43

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