I’ve got a board that I planned to fab at one of the Asian prototype shops I work with, but they seem stumped by the edge plating request. With other vendors I normally just call it out in the fab drawing and in the gerber files I have the ground planes on the inner layer extending through the edge to indicate those are attached to the edge plating.
I’m wondering if I should chalk this up to a vendor issue or if there is a better way of indicating edge plating. I’ve got features too close to the edge of the board to use castellated vias.
Thanks!
De facto way to imply edge plating is to have copper which reaches over the edge line, and then to tell them explicitly or in a way which they suggest. But there’s no standard way which would work everywhere. Many such things are limits of exported information exchange file format rather than limits of KiCad. Despite gerber being a standardized format it has many things left for interpretation in practice, and not all parties can even interpret the up to date standard correctly.
It’s also possible that a cheap manufacturer doesn’t do edge plating.
I have not send out many PCB’s formanufacturing myself, and none with edge plating, but I do read a lot on this forum and elsewhere.
As far as I understand some manufacturers very much dislike to do edge plating, while others are happy to oblige to the the customers wishes.
For some of the cheapest manufacturers the rule seems to be that they do not want to do anything that deviates from their standard process, which is understandable, as manual intervention costs time, time = money and the margins are small.
So if you’ve already found a manufacturer that works for you then just stick with it and accept that it’s probably not the cheapest in the world.
If you want to go manufacturer hopping, then start with small batches and make notes of how well the communication goes.
The Gerber job file can indicate whether the PCB is edge plated or not. 
See if your pcb manufacturer has a web page about “castellated” holes. These are generally half rounds on a pcb edge and have plated edges.
They may not do castellated or will charge you more.
This is an extra process step after routing out the boards from the production panel, so it will be a cost
???
This does not make sense to me.
Normally the “routing” part of the PCB’s is the last step, and after that the PCB is a finished panel or loose PCB’s.
It would be much more logical to route slots for the edge plating in the same step as the drilling. so both the via’s and the edge plating is made in the same process step.
Via plating is normally done by first applying a very thin and slightly conductive layer on the inside of the holes, and then by growing copper in the holes by electrolysis, which needs electrical conductivity. This step is done early in the production process, before the tracks are etched and the PCB still has copper over the whole area and is therefore conductive. The electrolysis process deposits copper over the whole area, and the top and bottom layer usually grow in thickness from 17.5um to 35um.
Possibly this also explains why some manufacturers just do it, while other’s don’t. Maybe some of the PCB manufacturing machines are highly specialized and can only do the drilling part, while other manufacturers have machines that can do drilling and routing on the same machine with automatic tool change.
Some manufacturers drill 3 boards at the same time and possibly milling can not be done with 3 boards at the same time because of side loading of the mill, but this is speculation. Once you get to these details there will be many differences between different PCB manufacturers.
Eurocircuits has made a series of video’s about PCB manufacturing and put them on youtube, and it’s worth watching if you like this sort of stuff. It has quite a lot of details about their production process for PCB’s.
Remember that the cheap PCB fabs share a PCB panel across several customers
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