Screaming Circuits: Start the Year Right, without PCB placement overlap

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Start the Year Right, without PCB placement overlap

Today's illustration isn't a super-bad problem. You can usually make this work - unless  you've got to align up with a hole in case. I'm talking about the venerable 3.5 mm audio jack. They aren't used all that often these days, but when they are, one of the most common formats has a design detail that makes edge alignment pretty critical.

3.5mm jack recepicalThe part of the connector that receives the jack is a short barrel, with an outside diameter larger than the height of the rest of the connector, as you can see in the image on the right. It comes in thru-hole and surface mount varieties.

This means that you have to have your solder pads or holes just the right distance from the board edge. Too close, and you can violate design rules. Too far inset, and you won't be able to mount the connector flush.

IMG_3358

This part can cause additional problems if your board is panelized. Like other overhanging connectors, the panel tabs, panel rails, or other boards in the panel may make it impossible to mount the part, even if the spacing is correct.

The board shown below has both incorrect spacing, and another board in the panel blocking placement. The surface mount pads allow for more flexibility in positioning - it would have worked if not in a panel.

IMG_3323

I've done this myself. Speaking from experience, I can say that it's easy to avoid, and quite sad when discovered at assembly.

Duane Benson
Down at the edge, close by a panel rail
Close to the edge, round by the routing tab

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