Solution for plated slots at OSH Park - Page 1
Forum section: electronics / general

author: gcardinal
author_rank: Unknown
timestamp: May 22, 2014, 11:31:42 pm
content: Just wanted to share my experience with getting small plated slots manufactured by OSH Park.OSH Park onsupport pagehas a following statement:"All internal cutouts will be unplated, and must be 0.1 inches (2.54mm / 100 mil) wide. "But in my recent PCB, I had 0.8x2.8mm slots with plated pads on both sides and plating on the inside as well. A bit hard to see inside-plating - but continuity test from one side to another produced a clear signal.I actually used a very old version of P-CAD, but solution is pretty much the same and is well described here:http://kuzyatech.com/altium-board-slots-and-osh-parkAlso I must add, that I only have experience from 1 batch of 3 boards made from P-CAD output. I don't have precise tools to measure it, but based on reading I could get I would say it is at least within +/- 10%.

author: Kjelt
author_rank: Super Contributor
timestamp: May 23, 2014, 07:39:14 am
content: Just thinking out loud:Since OSH park is a community service they do not produce the boards themselves or are they?So how many pcb manufacturers do they co-operate with and how many of those do support this service?Say they have 5 factories and only 2 of them support this service, then they can not guarantee it or advertise with it.

author: gcardinal
author_rank: Unknown
timestamp: May 23, 2014, 08:11:43 am
content: Quote from: Kjelt on May 23, 2014, 07:39:14 amThat is a very possible scenario. Most likely specs are set so high that its not a problem to produce them by a range of factories.However for my project and my design it is vital to have slots, so I do take the risk - its only a prototype anyway

author: gregariz
author_rank: Frequent Contributor
timestamp: May 23, 2014, 08:12:20 am
content: Quote from: gcardinal on May 22, 2014, 11:31:42 pmI read that statement to mean cutouts rather than slots.Cutouts would be holes etc in the pcb that you would define in the keepout/board outline layer/gerber.Plated slots would normally be defined in the drill file.At least thats how I have always done it.

author: gcardinal
author_rank: Unknown
timestamp: May 23, 2014, 08:18:33 am
content: Quote from: gregariz on May 23, 2014, 08:12:20 amWell yes, but if you do it that way it wont work as software at OSH Park will reject slots file. So this is a workaround to make slots without using slots function.For me (please correct me if Im wrong) a slot is a not circular cutout, plated on the inside and with plated pads.Solution it self is not new, but the way OSH Park describes it - it must be at least 100mil wide - however I got slots which are half that width.

author: gregariz
author_rank: Frequent Contributor
timestamp: May 23, 2014, 08:43:37 am
content: Quote from: gcardinal on May 23, 2014, 08:18:33 amWere your slots defined in the drill file AND in the keepout?My understanding is that the reason that cutouts are defined in the keepout is that is a post processing operation done at the end of a job after plating, mask and silk has been applied. Its also the reason they use a large milling bit as they drag the bit around any smaller milling bits will break at speed. This suggests your slots were done during the normal drilling process.

author: Allen393
author_rank: Contributor
timestamp: May 23, 2014, 09:55:39 am
content: Solution it self is not new, but the way OSH Park describes it - it must be at least 100mil wide - however I got slots which are half that width.Basically the min width of slot holes could be 16mil for lots of PCB manufacturers nowadays..

author: gcardinal
author_rank: Unknown
timestamp: May 23, 2014, 10:26:01 am
content: Quote from: gregariz on May 23, 2014, 08:43:37 amNo, only on keep-out layer, drill hole size is set to 0. And indeed it is a bit strange, since keep-out is also "Board Outline" layer in OSH Park world. And slots where clearly drilled out before plating.So the only explanation I can think off, must be merging of drill file with holes in keep-out layer and then sorting them to size. All holes under certain limit are drilled before plating and hole bigger then certain limit drilled out at the end together with board outline.

author: nctnico
author_rank: Super Contributor
timestamp: May 24, 2014, 01:36:45 am
content: Quote from: gregariz on May 23, 2014, 08:12:20 amNo. Unless someone finally invented a square hole drill. The usual solution is to have a slot inside a copper area on more than 1 layer. Slots are on the milling layer a.k.a. fabrication layer which has the outline of the PCB.