Edge plating can be achieved by placing the through holes on the edge of the PCB such that the inner wall of the through-hole coincides with the grid line as shown in the images below.
In order to get the flat line in the hole coinciding with the grid, the hole shape should be selected as oval as shown below.
That’s not reliable, I guess the manufacturer will ask about your intention. SMD pads could be used for the same purpose.
Thank you - that is very similar to what I need. I could have the whole edge plated, then file the gaps myself if it’s the intermittency that’s the problem. I can move the relevant contacts back from the edge by whatever distance the copper will overlap, and if the ones already connected with vias are joined it won’t matter, but the offset ones that have to be connected along the edge of the board won’t interfere with their neighbours.
I’ll enquire further with some firms and see what requirements they need. Otherwise, I could do just the normal front and back sides, and manually solder the two extra pieces on.
I can upload the KiCAD file if someone would be able to look it over for me, and say which files need to be together for it to be comprehensible by another computer.
After a recommendation, I have been in contact with Eurocircuits and so far I am extremely impressed. Despite being an inexperienced hobbyist, the UK representative has called me twice to discuss the requirements and offered advice which I am going to spend this weekend working into the board design. It appears basically possible to do this switch using round-edge-plating, but there may be a bit of jiggery-pokery required like drilling on the board edge to separate the contacts. I’ll report back.
I realise it will be significantly more expensive than one of the Chinese firms, but having read their blog post on why the prices are what they are, I agree entirely.
I have been having some really useful feedback from Steve Jones at Eurocircuits, and the specialist who has been investigating ways to help me make this switch as a PCB. I’ve been blown away by the customer service - it’s one of those things that just makes one happy to engage, and it’s been a delight, even as an idiot who doesn’t understand the KiCAD programme and hasn’t any experience with PCB manufacture.
It appears it might be possible to make the switch using vias in the centre of the board, which is a contact dead-zone. The specialist thinks this is easier than edge plating parts of the board, or trying to lap-solder manually after the PCB has been made.
However, it requires re-drawing my KiCAD PCB and I wondered if anyone had any resources that would help me. The specialist’s feedback is:
He should use “pads” and “traces” to make the design.
He does not do so, and now there is no distinction in his design between copper pads, and hence the pads that we can free of soldermask, and traces that connect the pads, which could be covered with soldermask).
Basically customer has made 1 giant customer footprint in his library for the complete slider….with different pin connections:
In the above pic, area marked as 13 is “one complete” pin connection, while in fact it consists of 3 pads, 2 smaller ones and a longer on, connected with traces.
Basically the customer made his pcb design in the footprint editor of Kicad, while he should use the footprint editor to define the “FootPrint”, and then use Kicad itself to make the pcb design, being a connected bunch of components. Where in this case the components are the individual connection pads…
So I would not design the footprints as customer did, I would make 2 SMD footprints in general:
- one for the smaller version of the connection pad à like pad 11 in above pic
- one for the larger version of the connection pad à like pad 9 in above pic
Looking at it further, it is probably ONLY needed to create the Small version of the footprint.
Because I think that the “long” version of the footprint is in fact nothing more then 2 adjacent small footprints, connected with a wide trace.
With these 1 small (or 2?) footprint you can create an – or 1 - SMD component.
And then you add as many as needed of that SMD component to the design.
You then place the SMD components where they are needed on top and bottom,
and you connect them as needed by traces, small and big ones, you can use vias, etc…
To create the copper areas on the left and right of the slider pcb, you can use copper fill, or copper pour.
Of course, if you first draw the schematic – defining the components and their connection between them - then designing the pcb is a piece of cake.
Of course, in this instance there is no schematic as there are no components. I was drawing in a CAD drawing programme as I was following an online tutorial on how to make unusually shaped pads.
I’m back on this and have struggled my way through what could be a suitable PCB method.
I’ve made an SMD footprint from a set of lines, a polygon and a pad, combined to form a new pad. I hadn’t grasped that using the lines and polygon tools like a paintbrush, rather than for creating a single shape with a fill was a valid option. I was struggling to get the curved edges with the polygon, as of course it only does straight lines.
I’ve used the footprint of the smaller of the two contact types, connecting two of them with a wide trace to make the larger ones.
Another option, if you actually need an edge contact surface, is wrap a flexible film PCB around a piece of plastic and putting some foam behind the contact edge. Have mechanical holes in the film and plastic holder and fix it with a plastic rivet. See for example this EEVBlog video (HP-41CV teardown, though I think that’s an HP-41CX PCB actually) at 7:10:
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