PCB Assembly Services - Screaming Circuits: Cat Chow


Cat Chow

I recently wrote a bit about eating my own dog food relative to a small design I've put together. Today, I'm moving along with that process and kitting it all up, so I thought I'd pass on some hints on making a good parts kit. I'm looking at this from the perspective of Screaming Circuits, but my guess is that it would fit for just about anyone assembling your prototypes. Even George's PCB Assembly and Dry Goods Emporium down past the railroad tracks.

If you're sending all of the parts, you can leave them in the original package. Just be sure to clearly mark the packages with your reference designators. If you've got to cut your strips down, you may need to Downsized_0418110808 re-package the parts, as I am. I got these little handy dandy anti static bags from Digi-Key (part number 16-1032-ND) for less than ten cents each in a pack of 100. You can use the little pink anti-static bags too.

I've labeled each bag with the reference designator, the component manufacturer and the manufacturer's part number. The more ambiguity that you can remove without adding excess clutter, the better. Making the labels was easy. I used Avery #5366 labels and mail merged from my BOM spreadsheet.

You can also put the component value on the label as well, if you can do it without clutter. Maybe line 1, reference designator; line 2, manufacturer and manufacturer part number; line 3, component value. Once you've got the bags labeled, go ahead and fill them up with the parts needed for your assembly. Add in 5% extra just in case (50% extra for 0201 passives).

If any of your parts are moisture sensitive either leave them in the original moisture barrier packaging or let us know that they need to be baked prior to assembly. That will prevent popcorn in the reflow oven.

Duane Benson
You'll like it better or my name isn't Orville Partenbacher



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Labeling the components in a kit is critical if you want your build done right. Personally, I prefer to have an index or line item number column in the BOM (unique number starting at 1).

Then, when kitting I just have to label each component type with something simple like "Line Item 1", "Line Item 2", ....

This more easily allows for subbing parts without causing confusion. For example, if the package label says 33R 5% then I can slap a label onto a digikey pack with 33R2 1% without conflicting labels. This sort of subbing happens alot on hand or proto builds. Same thing for a tube of Microchip parts subbing for what will be a reel part in production.

It also removes the step of having to print project specific labels and importing BOM's to print the labels.

The downside is that the assembly people won't know if it's right or wrong--so be sure you put your labels on correctly.



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