Electronic – Searching for exotic SOT23 P-channel mosfet where source drain swapped

mosfetpcb-assemblypcb-designsurface-mount

Due to an error in the layouting process a batch of PCBs has to be scrapped. Instead of the standard pin assignments:

  • 1 – Gate
  • 2 – Source
  • 3 – Drain

we used:

  • 1 – Gate
  • 2 – Drain
  • 3 – Source

As a last resort before ordering new PCBs I would like to ask you if you ever came across a P-Channel Mosfet (SOT23 package) where the source and drain pins were swapped?

Best Answer

Several things:

  1. Unless you were being irresponsible, these are prototypes and you only need a few working units for further testing. No, don't try to get some exotic part that you won't end up using in the production version. Manually fix these few now, continue on with testing, then fix that next rev along with whatever else you find this rev.

    This sort of screwup is part of what prototyping is for.

  2. If these are production boards, then you first need to fix your process. What the heck were you doing ordering a large batch of untested boards!? Stuff happens. Never expect the first rev to end up being the production version. Shame on you if this is what happened. Where was your chief engineer when the kid ordered 100 boards of his new design?

  3. Boards are relatively cheap before you put parts on them and pay for the labor to stuff, test, and possibly calibrate them. Currently you have a small mistake. Don't throw good money after bad and make it a big mistake.

    Build a couple boards, fix the flipped component manually, and then go on to find the other screwups that you don't even know about yet.

  4. Stay after work and write on the whiteboard 100 times "I will never order large quantities of untested boards again.".

Never think you've found the last problem until you have a working board in your hands. Again, the chief engineer should be enforcing this, even if there are a bunch of impatient immature junior engineers working there. This is much more of a company process problem than a minor footprint screwup.

Related Topic