# Is it always bad for the PCB to touch the enclosure?



## Grubb (Jul 2, 2021)

I'm working on a 1590a build and while I thought I had checked measurements, a test fit has revealed that my PCB is touching both sides of the enclosure. Obviously I wasn't cautious enough. I could sand back the edges of the board to get 1-2mm clearance, but this could still easily travel once boxed up. This is the noobiest of questions, but is it a total deal-breaker for the edges of the PCB to touch the enclosure?


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## BuddytheReow (Jul 2, 2021)

box it up and see! If only the board and not and of the leads/components/any metal are touching the enclosure you should be ok


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## Stickman393 (Jul 2, 2021)

Some folks design PCBs to be supported by little grooves in the sides of an aluminum enclosure.  Slide in/slide out.

The PCB itself is made of an insulating material: typically some kind of epoxy-saturated fiberglass board.  Or something.

The traces and solder joints, though, need to be kept clear of anything conductive.  Solder mask helps with the former.  Make sure that your leads aren't butting up right against the edge and you should be good.

The thing you want to watch out for here is a short.  Low voltage stuff like a guitar pedal: it's difficult to do much damage, aside from to the components in the pedal.  The real danger comes from working with line voltage, if one was to not bond the chassis to ground and a stray PCB solder joint just so happened to make contact with the enclosure...

It'd sit there like a bomb, just waiting for some unsuspecting sap to offer up themselves as a suitable path back to the source.


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## danfrank (Jul 2, 2021)

I only scanned the replies so this may have been covered already, but when in doubt, put a strip of black electrical tape on the inside of the enclosure where the PCB may rub up against the enclosure. This is only a problem where there are copper traces at the extreme edge of the PCB, which most PCB makers try to avoid. Most PCBs have at least a tiny bit of PCB material (fiberglass) on all edges


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## Feral Feline (Jul 3, 2021)

Be careful sanding back the edges of the PCB, as there may be a signal trace or other trace that follows the edge.
Not as critical if it's just ground plain (if the circuit grounds the enclosure via the jacks anyway).

I've done it, filing/sanding the edges of a PCB to force-fit into 1590A. I've even notched out corners, and drilled through to make room for switches. 

PROTECT YOUR EYES, LUNGS AND SKIN. 
The fibre-glass dust created doing these types of mods is at the worst toxic and at the least irritating.

Alternatively, I've also clearanced the enclosure — board or enclosure, your choice — on rare occasion a bit of both!

Should you attempt it... just be prepared to sacrifice your time, effort and especially the board to the altar of experience.


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## music6000 (Jul 3, 2021)

Grubb said:


> I'm working on a 1590a build and while I thought I had checked measurements, a test fit has revealed that my PCB is touching both sides of the enclosure. Obviously I wasn't cautious enough. I could sand back the edges of the board to get 1-2mm clearance, but this could still easily travel once boxed up. This is the noobiest of questions, but is it a total deal-breaker for the edges of the PCB to touch the enclosure?


If it is the ground plane, you will be OK.
Test for continuity with your DMM from ground pad along edges of board if you see metal.
If you have continuity your safe!

If it's a PedalPCB Board, which one?


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## Grubb (Jul 3, 2021)

music6000 said:


> If it is the ground plane, you will be OK.
> Test for continuity with your DMM from ground pad along edges of board if you see metal.
> If you have continuity your safe!
> 
> If it's a PedalPCB Board, which one?


Thanks for the tip. It's not a PedalPCB board, it's my first attempt at making a simple fabricated PCB design based on an Em-Drive. But I obviously got a measurement wrong somewhere!


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## Mcknib (Jul 3, 2021)

I usually use non conductive kids craft foam to insulate the pcb from the metal box, but if it's a tight fit you can nick some of your Mrs's nail varnish and paint the enclosure bits you think might short on something, once it's dry it'll form a fairly robust barrier

Obviously don't steal the stuff with metallic flakes in it I only steal that when there's nobody else in the house and I'm dressed in.....

Damn how'd ya delete messages I don't really do that.........

Her girdles kill me...they're defo a tight fit!


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## music6000 (Jul 3, 2021)

Mcknib said:


> I usually use non conductive kids craft foam to insulate the pcb from the metal box, but if it's a tight fit you can nick some of your Mrs's nail varnish and paint the enclosure bits you think might short on something, once it's dry it'll form a fairly robust barrier
> 
> Obviously don't steal the stuff with metallic flakes in it I only steal that when there's nobody else in the house and I'm dressed in.....
> 
> ...


Is This How You Get Around ?  :


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## Mcknib (Jul 3, 2021)

music6000 said:


> Is This How You Get Around ?  :


Haha caught mate


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