EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: codingwithethanol on November 07, 2019, 05:39:13 am
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I was working on a PCB design, and I found that the switch I had chosen has little plastic support feet which protrude into the board. This translates to having 2 little holes through the board which interfere with the silkscreen design on the opposite side. I was wondering if you could specify that a hole not be drilled all the way through the board, just "half way". I googled PCB half hole but that's used to mean literal semicircle holes.
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Why, our gracious host Dave's latest video was on the very topic of PCB fabrication options! Have a watch, starting at 58:40 or so.
It's usually called something like Z-axis milling or controlled depth drilling, and it's a rather expensive extra. Maybe it's better to just take snips to the support pins, choose an alternate switch, or leave copper off that area and machine the holes yourself upon arrival.
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Thanks! I'll either trim the supports or just leave it be. Appreciate the info.
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I assume it is for the aesthetic of the badge? If so, maybe make it as a VIA and then tent in on the backside if you want it cheap
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Those are guide tabs, which also serve the important purpose of providing mechanical stability and robustness. Without them, the part might easily break off when "switched".
It's no problem to use (non-plated) through holes for the tabs, in fact I think it's the norm.
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Yeah. Those posts are there for a reason. They locate the switch precisely, and also probably take excess force off the solder joints.
Also, cutting them properly flush for mass assembly sounds a bit expensive, and error prone...
Can you just dab some white paint on the logo holes after assembly? Or move either the switch or the logo? Or maybe look for alternative switches that aren't designed to use those posts?
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Paint is seconded. Or put a sticker or white tape over it or whatever. Far cheaper than ordering protos with a custom process (blind hole).
In production, I think a squirt of white adhesive would do it. (Idle thought, do they have CNC silastic applicators, or is that largely still a hand operation?)
Tim
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The correct answer might be the easiest: use another type of switch.
Although if it is just a hobby project and you don't mind tinkering just cut them off like others have suggested. I'd increase the pad size in that case to provide a bit more mechanical support.
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Apologies if I missed this, but why can't you juut move the component designation on the silkscreen?
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I'd go for a different switch. Surely you can find a variant without guide holes?
Anyway, largely depends on how much you value the esthetics of the badge ;)
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Apologies if I missed this, but why can't you juut move the component designation on the silkscreen?
I don’t think that’s the issue, since it’s the pair of small holes that are at fault here. I’m pretty sure they’re referring to how they appear as dots between the Viking helmet’s horns on the opposite side of the PCB. I think the big hole is for the lanyard.
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If you really wanted the really clean solder mask finish, I would suggest a four layer board with blind holes for your mounting tabs. Not the cheapest option, but your finish would be as good as you could get.
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Let me reiterate: For this switch you need the guide holes. If you don't want holes, pick a switch desgined to not need them i.e. a bigger one with more robust solderable pads.
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Reposition the switch, such that the two holes fit in as the viking's eyes. ;)
(Or nostrils, depending on the scale of the image...)