What’s Missing?

LED cathode There is something about this PCB that will likely cause trouble for anyone assembling it. The first three people to correctly identify the issue get a Screaming Circuits 1 GB USB drive.

I know, this day and age, 1 GB doesn’t sound like much. But you can still put a bunch of pictures on it. More important, you can use it to back up your CAD files just in case disaster strikes your workstation.

This issue is, unfortunately all too common. It’s probably a case where the designer knew exactly what they were intending and could easily build it up without any problems. However, when sending it out to a third party for assembly, that “in the head” knowledge doesn’t help much. If you’ve got a PCB that you’ve been assembling yourself and later send out for assembly, make sure you aren’t assuming that the assemblers can derive what’s hidden in your brain.

Duane Benson
Beware the monsters from Id.


11 thoughts on “What’s Missing?

  1. Part designator is incorrect. Should be related to a symbol that reltes to the BOM.

  2. I agree with all of the responses so far. Also – love the ‘Forbidden Planet’ reference – RIP Anne Francis and Leslie Neilsen

  3. 1- no polarity on LED (by pad shape or silkscreen)
    2- silkscreen text too close to edge of pcb
    3- no component designator (“D” number)
    4- funky trace routing (keep life simple -unless required- use 45 degree bends.
    5- for thin traces going into a larger hole pad.. should have “tear drop”
    otherwise risk trace fracture at edge of pad.

    should I go on?

  4. Pete…………..! Why is the LED glowing at me???
    Oh! Man I can’t believe this people; I told Mike that we need to bend the leads and align the LED’s with the case panel…
    Oh, Really! Call them again…. I need ten good boards by @10am!!!! Tomorrow!

  5. Brent, Brian H, Mike, Steven O, George W, Mark V, John L and Juan N – you’re more than three, but that’s okay. If you’d like the flash drive, email your mailing address to [email protected]. I won’t keep it. I’ll just used it for the mailing label.

  6. George: It might be the only LED in the BOM, and called out that way, so LED would not be ambiguous. Fishy, sure…

    Also fishy, but not “missing”:

    1) whatever’s going on in the silk-screen to the left of the LED footprint (y1? where does it go? or is it a test point? etc.)

    2) the way the silk screen labels cross what looks like a scoring mark? or is that a trace?
    if it’s a trace, is it too close to the pad on R23? Hard to tell from the photograph.

    3) inconsistent capitalization of the parts designators

    And yes, I agree the routing is unlovely.

    But none of those really fit the scenario of the designer having all the information to build the board himself or herself without any problems.

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