We're getting to the point of diminishing returns!

You've really gone a little overboard with the ground planes! Maybe to your detriment. You really don't want thin parts of the plane going nowhere such as around your optocoupler tracks - they're just antennas. Make sure they connect up to the rest of the plane at the other end or just eliminate them. If those tracks were carrying high speed digital signals - then you would definitely keep the tracks and have them encircle the high speed track.

In this instance it's not a problem as I don't think the frequencies involved are going to cause an issue - but you've done this despite having a wire link - get rid of the wire link and sacrifice your ground plane around here.

What are you going to do with the shield of your db9 connectors? Are they to be grounded?

Are you expecting to have your 0v grounded to the case? If not, have some clearance around your mounting holes.


It seems you're really worrying too much about the pcb and not the whole system. If you were worrying about CE compliance, then the ground plane is a good thing, from your design it seems you're not interested in CE compliance so why worry too much about the ground plane - I've seen commercial products that are CE compliant and are switching nastier loads on single sided pcbs! I only have to look in my washing machine! The fact that you were willing to trade creepage distance for ground plane suggests you're not understanding the reasons behind a lot of the suggestions given. Putting ferrite beads isn't going to make your product any more reliable but it will go towards making your product EMC compliant!

This seems to be a commercial product and whilst it is ok to ask for some guidance, it seems you need to do a bit of research to get a better understanding of the whole solution rather than just be guided by a handful of comments on a internet forum. Us respondants are only seeing a small part of your problem, so we can only give a small part of the solution. Ultimately, the success or failure of this product is up to you. If you are unsure of your design, pay a consultant to review it for you - the money will be well spent.