Screw terminal for PCB and seeking any ideas - Page 1
Forum section: electronics / projects

author: tryingtolearn
author_rank: Contributor
timestamp: January 09, 2025, 11:04:31 pm
content: Looking for a way to attach a socket (Home designed and 3d printed ) to a pcb.Looking at an old motherboard the cooling set up used a type of screw terminal (See pic)It seems to have just used an adhesive to attach to the board.Is there a name for this ? and is there a better way to go about it?maybe a lower profileStarted to look on digikey but not exactly sure how to phrase the search to narrow it downthanks for any advice.

author: Benta
author_rank: Super Contributor
timestamp: January 09, 2025, 11:23:45 pm
content: It's not glued, it's pressed in.Look for "press fit pcb nut" or something like that.

author: tryingtolearn
author_rank: Contributor
timestamp: January 09, 2025, 11:26:53 pm
content: ok thanks, ill start there.Just assumed glue since some of the laminate came off with it.Is it just pressed into that tiny via??

author: tryingtolearn
author_rank: Contributor
timestamp: January 09, 2025, 11:30:14 pm
content: Broaching Nut seems to be the termThanks for that!

author: mtwieg
author_rank: Frequent Contributor
timestamp: January 09, 2025, 11:34:49 pm
content: Looks like it was soldered to the PCB, and tore off the pad and some of the dielectric with it.Soldered-on threaded inserts are fairly common,see here for an example. These are referred to as surface mount, but they actually require a plated through hole which they sit inside. This greatly increases their strength, and gives better alignment as opposed to just being soldered to a surface pad.Quote from: tryingtolearn on January 09, 2025, 11:30:14 pmBroaching nut are press-fit, not soldered. Yours doesn't look like a broaching nut, if it was it would have left a much bigger hole in the PCB, and you'd be able to see the "teeth" on the nut.There does seem to be some sort of small hole in the center of the pad, but it's not clear what it was for...

author: PCB.Wiz
author_rank: Super Contributor
timestamp: January 09, 2025, 11:57:02 pm
content: Quote from: mtwieg on January 09, 2025, 11:34:49 pmYup, soldered SMD nut. It's a bit Hail Mary to attach a heatsink that way.The hole is likely there to allow venting and some solder wicking and encourage centering during reflow.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 10, 2025, 12:09:07 am
content: Quote from: PCB.Wiz on January 09, 2025, 11:57:02 pmSome SMD nut/bolt parts have a small pip at the centre to aid alignment and improve strength

author: mtwieg
author_rank: Frequent Contributor
timestamp: January 10, 2025, 04:07:26 pm
content: Quote from: mikeselectricstuff on January 10, 2025, 12:09:07 amYeah I'm betting that's what it is, you can see the same barrel on the bottom of the nut in the last photo. Looks like it sheared clean off.

author: langwadt
author_rank: Super Contributor
timestamp: January 10, 2025, 04:22:37 pm
content: Quote from: mikeselectricstuff on January 10, 2025, 12:09:07 amor have a step and is supposed to be mounted on the opposite with a through holee.g.https://www.digikey.dk/da/products/detail/w-rth-elektronik/7466003R/4915484

author: Hydron
author_rank: Super Contributor
timestamp: January 10, 2025, 04:28:51 pm
content: Wait what, someone used one for a heatsink mount?They are very common for stuff like M.2 drives and other applications where you don't expect high forces. I have gotten away with them for mounting Jetson Xavier NX and Nano modules (SODIMM form factor with added mounting holes) but that's about as far as I'd push things.If you're planning on using it for mounting heavy stuff then look at something with a larger through hole that can be soldered on the other side with the screw going through and clamping on the board. Add some loctite so that you're not relying on FR4 maintaining preload on your thread.

author: tryingtolearn
author_rank: Contributor
timestamp: January 11, 2025, 01:31:50 pm
content: Exactly what it was. put the board on the hot plate and the second came off clean. Looks like it should work for what Im trying to do.

author: tryingtolearn
author_rank: Contributor
timestamp: January 11, 2025, 01:36:56 pm
content: Quote from: Hydron on January 10, 2025, 04:28:51 pmlooking now - not a tremendous amount of force but the socket will have a flip lid requiring a minimal amount of torque. Considering the difficulty of removing the soldered one in the pic it should suffice. going to look at some throughhole as you suggest as well but will depend on the profile - the thinner the better.Thanks for the input and time.