Standard drill size? - Page 1
Forum section: electronics / general

author: tppc
author_rank: Regular Contributor
timestamp: June 15, 2021, 08:24:42 am
content: Hi there,I just finished the design of my first PCB on JLCPCB's website.before placing the order, I was just wondering if there is a standard drill size for- Through hole 0.25W resistors ?- Through hole DIP8 sockets ?what puzzles me, is that available footprints on EasyEDA use strange drill sizes like 0.711mm or 0.914 mm for example.Does a 0.711 mm drill even exist?What will happen if I order a PCB with 0.711 mm holes? Will they round it to the next standard size?BTW, is there a list of standard / recommended hole sizes for classic through hole components?Thanks for your help.Kind Regards.

author: tppc
author_rank: Regular Contributor
timestamp: June 15, 2021, 09:32:04 am
content: Hi evb149,Thank you very much for this very precise and detailed answer.hey hey, I found the 0.711 mm & 0.914 mm drill bits from your wikipedia linksAgain, thank you very much for your time.I am already reading the information on the links you indicated.As per the pdf drawing they suggest simply 1 mm holes.In the case of my first PCB, hole sizes are not critical, I just wanted to use hole sizes that make sense.Kind regards

author: PlainName
author_rank: Super Contributor
timestamp: June 15, 2021, 02:22:11 pm
content: You might find this article useful:https://www.pcb-3d.com/tutorials/how-to-calculate-pth-hole-and-pad-diameter-sizes-according-to-ipc-7251-ipc-2222-and-ipc-2221-standards/

author: asmi
author_rank: Super Contributor
timestamp: June 15, 2021, 05:55:15 pm
content: I don't think any pcb fab still use imperial drills, certainly none in China. They typically take the closest size up.

author: Feynman
author_rank: Regular Contributor
timestamp: June 15, 2021, 06:20:33 pm
content: Many shops have drill bits in 0,05mm steps. Since your specification is considered "finished" by default the shop will pick a slightly bigger drill to account for plating thickness and your tolerances (if specified).

author: tppc
author_rank: Regular Contributor
timestamp: June 16, 2021, 09:30:05 pm
content: Hi guys,thanks for all this valuable information.I really do appreciate the high level of expertise, good will and mutual help on this forum.Kind regards

author: viji_rookie
author_rank: Contributor
timestamp: July 12, 2021, 07:41:34 pm
content: I agree. Once IPC rolled out Standard packages land pattern for SMD packages. Similar in line thru- hole padstacks got formalised in my companies I worked so far. For an example 0.05mm is considered as step increment (no intermediate values) while defining the drill sizes which are typically more than 1mm . Achieving precise drill size is offered by few suppliers but at the cost consideration.We used below thumb rule in line with IPC guidelines as below,Finished drill hole FDH = Max lead size (with tol) + 0.2mm or 0.15mm (based on plating requirements)Then follow the IPC soldermask definations to attain at least minimum annular ring. Pls check link and attached picture.IPC-7251 Generic Requirements for Through-Hole Designhttps://pdf4pro.com/cdn/ipc-7251-generic-requirements-for-through-hole-design-49ebd1.pdfHope this helps.Quote from: Feynman on June 15, 2021, 06:20:33 pm

author: Mattylad
author_rank: Regular Contributor
timestamp: August 15, 2021, 02:20:02 pm
content: The sizes the OP has are probably the metric equivalent of the original thou size that the library was created with.Imperial sizes will not be used any more, all shops have metric drills and use the nearest equivalent.IMO it's best to go through your library and optimise/organise your library into common drill sizes, odd balls cost more.

author: Cerebus
author_rank: Super Contributor
timestamp: August 15, 2021, 03:00:46 pm
content: Most of the major PCB shops will have their drills racked up with drills that range from 0.2 mm up to 6.35 mm (1/4") in 0.1mm increments (0.05 mm increments if you're lucky). They will automatically pick the drill that gives the finished hole size that you specify in your design. For plated holes they will pick a drill a bit larger, for non-plated they will pick the closest. In both cases they will specify some tolerance they work to on hole sizes and this gives them some slack in picking the stock drill they have to meet your hole size requirements. JLC specify +0.13/-0.08mm as their finished hole size tolerance.A general rule of thumb for picking hole sizes for through hole components is to take the largest dimension of the lead (diameter for a round lead, diagonal for a square or rectangular pin) and add 100 um (0.1mm).If you're obsessive you can go through the datasheets for your various parts and calculate exact sizes but for things like DIP pins and standard through hole resistors you're unlikely to come a cropper from picking a standard size and sticking to it.For example almost every common passive through hole component I ever use has 0.8±0.1 mm specified for the lead size - take the upper bound there 0.9 mm, add 100 um for solder and you end up with a 1 mm finished hole size.