0.008″ PCB trace isolation on my CNC

Due to a new design that I am working on, I needed to use a component from TI that only came in a 6SC70 package.  It’s a boost converter (TPS61221) that operates from an input voltage as low as 0.7V and has 80% or better efficiency in the 1-10mA range. It’s trimmed at 3.3V, which I’m using to run an ATtiny45V. The ATtiny45 comes in a fine-pitch package as well, an 8TSSOP that requires 0.009″ isolation between pads. I haven’t been able to get much better than 0.020″ with the tooling I have, so I have been looking for alternatives.

I found some mechanical engraving bits at Think & Tinker which is actually here in Colorado at Palmer Lake. Their URL descriptor says they offer “Instrument and PCB prototyping equipment”. They also sell carbide engraving bits, and the particular one I selected was the 60° cutter, part number #EM2E8-0625-60V. The bits came in a nice container and are labelled as having a 0.005″ tip. The shipping was also wicked fast. Granted, it’s only a few hours away from my location but I ordered them and got them in the next day.

Sony 135

I’ve only cut one board, but I’m really happy with the results. I successfully achieved 0.008″ isolation between the pads of the devices, and now I can finally route traces inbetween the pads of 0.1″ headers. I couldn’t do that before.

Sony 147

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Sunday, September 20th, 2009 CNC, Electronics

5 Comments to 0.008″ PCB trace isolation on my CNC

  • Jack Grimes says:

    I’m truly impressed! It is always fun to improve something done before. I kind of gave up on doing my own boards when the new tiny components became the standard.

    Haven’t forgotten the board I was going to send you -just haven’t gotten around to it (same with looking for your panaramic photos). Good to hear from you.

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  • [...] like to see the final product milling PCBs. We’ve always been a little jealous of the PCB milling setup that [imsolidstate] has in his [...]

  • Austin says:

    Hi. What is the lifetime (# of boards) of the drill bits? Also emailing this question.

  • imsolidstate says:

    I’m not really sure, I’ve easily made upwards of a dozen boards and I’m still using the same cutter and set of drill bits. As for the drill bits I’m trying to use as much surface mount components as possible, so these days I’m mostly drilling vias. Resharpened carbide bits aren’t too expensive anyway, you can get sets at drillbitcity.com or ebay.

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