Wire strain relief - how to? - Page 1
Forum section: electronics / general

author: stryker
author_rank: Regular Contributor
timestamp: March 20, 2013, 02:41:19 pm
content: HiI'd like to add some strain relief, where an attached wire first passes through the board before being soldered on but have had no luck finding a tutorial or explanation. Do you just place vias to do this, or is there a better way. And what size do you specify?I'm using 6.4.0 Light Edition and will be using Seeed's Fusion PCB service.ThanksGeoff

author: jeroen74
author_rank: Frequent Contributor
timestamp: March 20, 2013, 09:38:27 pm
content: Can't you just place a 'free' unplated mounting hole?

author: stryker
author_rank: Regular Contributor
timestamp: March 21, 2013, 06:42:58 am
content: That sounds like a good idea, only I suspect I'll need to make the spacing more than 0.1"...oops. Which one would you suggest, and will Seeed drill it at that larger size or will it only have standard mount hole drilled in it?

author: SeanB
author_rank: Super Contributor
timestamp: March 21, 2013, 08:23:22 am
content: Just place mounting holes ( 2 actually, spaced at least the drill diameter from each other) slightly bigger than the overall cable diameter. Check with the board house what drill sizes they use as standard, and use the one bigger than the cable. As well place the first hole more than 2x the diameter in from the edge of the board, so that it will have some strength. As well do not route traces in this area, and keep ground planes out. Soldermask is fine, along with screen print of the pad use.

author: stryker
author_rank: Regular Contributor
timestamp: March 21, 2013, 09:21:36 am
content: Thanks for your help guys.I recently ordered my first test boards from Seeed so included a random mounting hole (MOUNT-HOLE3.2) just to see what would come back. They're in the post now so hopefully will get more of an idea inside a couple of weeks.Their site says the following regarding drill sizes.Drilling Hole (Mechanical) 0.3-6.35mm / 11.81 - 250 milFinish Hole (Mechanical) 0.8-6.35mm / 31.50-250 milSo there's a range of holes there but no indication of the actual sizes available that I can find. I guess I'll try a small run with with mounting holes for the strain relief and see what returns after I've seen what comes back this first time.Cheers ! Geoff

author: Rufus
author_rank: Super Contributor
timestamp: March 21, 2013, 03:35:12 pm
content: Quote from: stryker on March 20, 2013, 02:41:19 pmA section of a board I did recently. Looping the wires through the board helps isolate the solder joint from wire movement. Better than doing nothing but costs almost nothing.If you intend to pull the loops tight through the board you have to be careful how far you let the solder wick up the wire strands.

author: stryker
author_rank: Regular Contributor
timestamp: March 21, 2013, 08:50:14 pm
content: Thanks Rufus - that looks like what I had in mind. What do you use in Eagle to create a hole that's not a via or tinned as you have?

author: Rufus
author_rank: Super Contributor
timestamp: March 21, 2013, 09:02:16 pm
content: Quote from: stryker on March 21, 2013, 08:50:14 pmI don't use eagle so can't help.

author: enz
author_rank: Regular Contributor
timestamp: March 22, 2013, 07:55:50 am
content: Quote from: stryker on March 21, 2013, 08:50:14 pmIn eagle this is called a hole.

author: stryker
author_rank: Regular Contributor
timestamp: March 22, 2013, 08:25:08 am
content: Quote from: enz on March 22, 2013, 07:55:50 amCtrl-H. Found it. Hidden in plain view like that. Thanks

author: stryker
author_rank: Regular Contributor
timestamp: May 20, 2013, 10:08:22 am
content: I'm pleased to report the boards are back and this worked a treat. Thanks everyone !