This page is intended to be an all-inclusive guide to getting your PCB made and assembled on the OEDK's PCB milling machine. If you learn a better or faster way of doing any of the things listed here (or believe there should another section) feel free to add it in so that others can benefit from your knowledge.
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Capabilities
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You should always clean the board after milling to reduce the number of copper shards left over by the milling and drilling process. While a good cleaning will not guarentee guarantee complete removal of artifacts such as copper shards, it certainly reduces the chance of such artifacts being present (especially smaller artifacts such as copper dust or fiberglass dust).
Beware that excessive cleaning will result excessive oxidation of the copper on the board. If you do not plan on soldering your components onto the board soon after you have cleaned the board, the fresh copper on the copper clad board will rapidly oxidize and make soldering harder if not nearly impossible. To mitigate the effects of oxidation on soldering effectiveness be sure to clean the board before soldering and use plenty of flux. While most solder has a inner resin flux core that is essential to soldering, you may find that the heavy oxidation that builds up on bare copper may require extra flux. Use a flux pen to apply a small amount of solder on the pad immeditely immediately prior to soldering just that pad do not apply flux to the entire board, it will dry up and move around on you and likely defeat the purpose.
Ultrasonic cleaners (such as the one in the machine shop) can be used for this purpose, but care must be taken that the bowl does not have random metal shavings or dust that have collected from cleaning machined items. These particulate may embed themselves in the isolation between traces and cause shorts. Always rinse the board after cleaning with the ultrasonic cleaner, failure to do so will result in a sticky mess and impossible soldering. This is because the cleaner uses a solution of water and industrial detergent, the detergent will leave a thin film behind that is intended to be rinsed away. Do not forget this step!
Inspection For Shorts
Due to the imperfect nature of the PCB milling machine, once a board is finished milling and drilling there can often times be little bits of copper
Tools you will need:
- Stereo Microscope
- Digital Multimeter (DMM)
- Xacto Knife
- Dental Picks
- Patience
- Thin strands of copper that are fully attached at 1 end and touch another trace or plane (NEED PIC)
- Thin strands of copper that are freely floating on the board but that have become embedded between traces in the isolation area.
- Thin strands of copper that are inside drilled holes or are poking up from a drilled a hole
- These strands may appear benign because they are inside the hole, but they can become a problem once you insert your part into the hole and the copper gets either pushed out the other end or connects the bottom pad to the top pad... etc
- Copper dust that has collected in the isolation area.
- This dust may not show up in a continuity inspection because the dust may not present a direct path between traces, however it does provide a low impedance air gap that could potentially shift into a full blown short.
Inspection For Ripped or Lifted Pads
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