PCB pattern for a mid-mount DC power jack - Page 1
Forum section: electronics / general

author: cowana
author_rank: Frequent Contributor
timestamp: November 27, 2014, 10:32:40 am
content: For a space constrained project, I'm being forced to use a mid-mount DC power socket, which mounts in a cutout in the board:The issue I am having is with the PCB footprint they recommend (see attached). The mounting holes they recommend to use have rectangular holes ranging from 0.7x1.2mm to 1.0x1.8mm. However, I will get this board manufactured by the usual cheap prototyping services, and sending off a design with such a small slot is slightly risky, and might not be made properly. As far as I see, the alternatives are:1. Risk it and send of the design with small slotsIf they can make it then that's great. However, chinese prototyping places have a habit of changing designs to match their capabilities without telling the customer. Most tend to say the minimum slot is 1mmx1mm - so I would need to expand the holes to this at a minimum - but whether they will actually do this is a slight unknown.2. Use round holes insteadThe issue here is the holes are right on the edge of the board - if round holes were used, they would have to be larger in order for the corners to fit - and that would interfere with the edge of the board (creating a DRC issue and possibly breaking the factory's drills).3. Modify the board cutout shape to enclose the entire connector, then just have surface pads by the pinsThis is a neater idea - however I probably wouldn't be able to get the factory to plate the edge of the board touching the pad. This would make it a bit weaker, but probably still fine. The only real issue here is there would be nothing to define the height of the connector - I would need to make a jig to hold it all in place as it is soldered.4. Cut off the vertical parts of the pins, making them sit on the surface of the board (SMD pads)Possibly the best idea in terms of ease of alignment - but a fair amount of work to do, and would weaken the mechanical mounting slightly...This is for low quantities (<50 boards) - they will be hand assembled so a small amount of modification/alignment work is not an issue. I'm siding towards option 3 - but would appreciate any feedback or additional suggestions.How are these connectors typically meant to be used? I can see there would be no problems if I could have very small rectangular holes made, but at these sizes they seem too small for normal slot tooling.Andy

author: rs20
author_rank: Super Contributor
timestamp: November 27, 2014, 10:43:29 am
content: Just a thought -- of the four edges of those rectangular holes, perhaps only the edge closest to the connector is really important. This means you may do well with much larger circular holes. My idea comes from USB type B connectors, which have a similar sort of clip, but the manufacturers generally suggest a massive circular hole of which only one little bit of that circle (again, closest to the connector) is touching the support pins.

author: 8086
author_rank: Super Contributor
timestamp: November 27, 2014, 11:09:13 am
content: You can use small slots with SeeedStudio and I believe also iTead.You can also use multiple small holes to achieve an "almost slot", like my example here: