What drill size should the pads be for this part? - Page 1
Forum section: electronics / general

author: TheBorg
author_rank: Frequent Contributor
timestamp: May 26, 2014, 04:07:36 am
content: I'm working on a footprint for a part in Eagle (this is probably my third pcb I've designed using the software, so I'm quite new at it).The part # in question is S 6B-PH-K-S inthis datasheet. The pin width is 0.5mm. So should I set the drill size at 0.5mm in eagle, or something like 0.7mm (which from what I've gathered is a more common size).

author: kikib
author_rank: Contributor
timestamp: May 26, 2014, 04:24:50 am
content: Since the pin width is 0.5mm the drill size should be a bit bigger, how else is it going to fit in the hole? You have to account for manufacturing tolerance for both the component and the PCB as they won't be exactly as quoted. Some datasheets will provide you with a tolerance. Also since it's a multi-pin part you will need to also think about any tiny deviations in tolerance which will have a carry through effect on the alignment of the pins with respect to the holes on the PCB.So for a pin width of 0.5mm you should provide a comfortable hole size and add a bit on top for manufacturing tolerance. Since you have 2mm pin spacing and 0.8mm hole (as example), you will have 0.4mm on each side of the pin and therefore still left with a 1.2mm spacing from drill hole to drill hole. So 0.7 to 0.8mm sounds reasonable but always check your footprint by printing it off and comparing to the physical part and obviously it's better to be able to fit the component than not able to fit it at all. You could then for rev2.0 PCB tighten the tolerances.

author: TheBorg
author_rank: Frequent Contributor
timestamp: May 26, 2014, 04:28:14 am
content: Sounds good. Thanks!

author: Monkeh
author_rank: Super Contributor
timestamp: May 26, 2014, 04:47:02 am
content: The datasheet actually tells you the recommended drill size.

author: TheBorg
author_rank: Frequent Contributor
timestamp: May 26, 2014, 04:47:00 pm
content: Quote from: Monkeh on May 26, 2014, 04:47:02 amHeh. So it does.Thanks again!

author: tszaboo
author_rank: Super Contributor
timestamp: May 26, 2014, 05:33:00 pm
content: Have you ever tried putting a R lenght square through a circe with the same diameter?

author: LukeW
author_rank: Frequent Contributor
timestamp: June 02, 2014, 09:01:43 am
content: Get the datasheet, look at the recommended PCB layout part of the datasheet, not the data on the component itself, and it says 0.7mm hole. So that's what you'd use, right?But then again if it's an 0.5mm x 0.5mm square pin, then that's 0.7071mm across the hypotenuse, and you might want a little bit more room for error, so maybe 0.75mm (not standard?) or 0.8mm.

author: TheBorg
author_rank: Frequent Contributor
timestamp: June 05, 2014, 04:37:03 am
content: Quote from: LukeW on June 02, 2014, 09:01:43 amIf there's one thing I've learned here, is that immideately after I post something I know I've made a stupid mistake. In this case, blowing past the PCB layout part of the datasheet while looking for it.Sticking with 0.7mm for now, and I'll double check when I get my parts ordered.

author: kizzap
author_rank: Unknown
timestamp: June 05, 2014, 06:49:59 am
content: x = L * sin ?°where:x = diagonal of the pin (and thus the minimum diameter)L = length of the side opposite the corner you are measuring from, and? = the angle from the adjacent side to the hypotenuse of the effective triangle (the hypotenuse being the diameter we are after), which in a square pin is 45°alternately: given a square with side lengths of Y:hypotenuse (min drill diameter) = sqrt(Y² + Y²)But I guess that is just pandering.