PCB footprint error  - Page 1
Forum section: electronics / general

author: ryands
author_rank: Newbie
timestamp: January 06, 2022, 05:17:27 pm
content: Hi All,I am a newbie and have a question about an error I get in Altium.I have the RJ45 footprint in attached image designed in Altium per the OEM data sheet.However I am getting the DR violation errors on attached image.I was wondering could I allow these DR violations or should I be redesigning the footprint?If the footprint needs to be redesigned what would be the best approach?Thanks in advance.

author: ajb
author_rank: Super Contributor
timestamp: January 06, 2022, 07:40:12 pm
content: That's kind of a weird footprint. Are those holes supposed to be plated? Even if you can get this to pass Altium's DRC your PCB fabricator may reject having copper right up to a hole like that without an annular ring.Generally for weird pad shapes that can't be made using the standard pad objects you would use a region to create the copper areas, and then place a small pad somewhere inside that to create electrical connectivity to it (you'll need to set the mask and paste expansion properties of the region to ensure you can solder it). In this case, I would probably do the same, and make the region follow the shape of the hole (optionally with some clearance around it to make the PCB fab happy, if that will work with the connector). If you make the through holes unplated that may also prevent the short circuit error, but I'm not sure.Assuming those pads and holes are just mechanical support, you can give them all the same designator, and then place one pin in the schematic symbol with that designator, so you can make one electrical connection in the schematic for all of the mechanical pins (since often they're all tied to the same metal shell in the part anyway). Even if you don't need an electrical connection to those pins, it's sometimes easier to connect them to gnd or whatever so you can stitch the pads to the ground plane with vias for better mechanical strength.As to the errors, it looks like those pads aren't connected to a net (unless you have net name display turned off?). You can choose to allow short circuits for pads that are not in any net by adjusting your design rules, and that should eliminate this error--but could possibly allow other more problematic things to get through, so make these decisions carefully. There are a huge number of options when it comes to design rules, so it's hard to provide more specific advice with knowing how yours are set up.

author: thm_w
author_rank: Super Contributor
timestamp: January 07, 2022, 09:20:35 pm
content: Should be not plated, plastic locating pins like this:https://catalog.weidmueller.com/catalog/Start.do?localeId=en_DE&ObjectID=1455220000I can't see the backfill adding much strength, but who knows.

author: Pseudobyte
author_rank: Frequent Contributor
timestamp: January 10, 2022, 07:30:55 pm
content: What a strange design for a connector. Don't know what weidmuller was thinking. I don't think it would be so hard to design a connector where the alignment posts don't interfere with the copper features. Maybe a minor lack of foresight when they retooled the THP stampings.