How to safely "float" boards...

[tehfunk]

I've used the search button A LOT and gathered a lot of information, but I'm one of those people who thinks you can never be too cautious, and am a little confused. So, I wanted to know some of the best ways you can "float" a board in a box (no mounting of any sort) and prevent them from shorting. Pictures would be helpful too.

Also, I am aware that any conductive materials touching the solder side of the board will create a short, but I am still confused as to whether the top side of the board (component side) can short, for example, if the metallic top of an electrolytic, touches the box or the back of a pot, will that cause a short? Thanks in advance!

Edit: When you open the box which side of the board do you prefer to have showing, the component side or solder side?

[Stellan]

The top side of the board CAN short out. I have had good results wrapping the entire pcb in thick plastic. It may not be a very authorised way to do it, but it works and keeps everything in its place

[Mark F]

MXR used to use thin foam rubber but it deteriorated after a time. It was a real mess when it went bad. I've used thin bubble wrap with good results.

[tehfunk]

The top side of the board CAN short out. I have had good results wrapping the entire pcb in thick plastic. It may not be a very authorised way to do it, but it works and keeps everything in its place

Would the electrolytic example I mentioned be a cause? I know exposed leads from vertical resistors can cause shorts on component side..

MXR used to use thin foam rubber but it deteriorated after a time. It was a real mess when it went bad. I've used thin bubble wrap with good results.

Could you post a picture of an example of this method, it would be so helpful?
Where do you get the bubble wrap? What size?

Sounds good. Other suggestions?

[Pushtone]

Cardboard from my Kornflakes box.

Craft stores sell 1/8" thick foam in 8x11 sheets. Cut to size.

When I get desperate I raid my six year olds craft box.
See bottom left photo. Foamie whale sticker (made out of the same 1/8" foam but cut onto shapes)


You can also try my nylon machine bolt mounting but nylon nuts and bolts are more expensive than foam sheets.

Try a search for "PCB mounting" and "standoffs" for more ideas. There have been a few thread about this.

[bumblebee]

i use double sided tape or glue and secure it to the back of the pots.

[bkanber]

I just use electrical tape to cover the board.. I suppose the top side of the board could short but this has never happened to me, and I've never done anything about it. I'm also considering using clear nail polish on the solder side, but if a component ever goes bad, it becomes annoying to desolder stuff, etc.

I also prefer to have the component side showing. I don't know why. I just like it better that way

[petemoore]

  Pretty much anything you think will work will work, IME>
 Just so you know I'm known as 'unorthodox' from time to time, and push the quickness of board mounting to utilize the 'free and available' to cause it to be done 'now.
 As long as you don't use conductive materials...
 Foam, EZ, quick, good, ugly until the coffin is sealed [hopefully no-one ever has to see]. It's the packing material that comes in boxes, a 'plastic-ey-styrofoam], it's possible to cut sheet with shears, I go around the outside, then cut the center ~flat, and make room for tall caps.
 Plastic sheet, heavy duty theft preventer type, shears required to open product, cut precisely just a little wide, clamps itself in the box.
 Makes a fine 'mounting sandwich', insulating HD plastic sheet across the substrate between the walls [or bend a side and have the plastic go up the wall[s also], foam fit to clamp lightly on top/
 I do like some fitted foam under the board bottom because I perfboard and clamping too hard can bend a wire-trace to mis-connect.  
 

[earthtonesaudio]

You could use an old plastic bag, cardboard, cut up old plastic bottles...

Many options that don't require buying any new products.

[tehfunk]

Cardboard from my Kornflakes box.

Craft stores sell 1/8" thick foam in 8x11 sheets. Cut to size.

When I get desperate I raid my six year olds craft box.
See bottom left photo. Foamie whale sticker (made out of the same 1/8" foam but cut onto shapes)

Interesting, but I don't know where I'm gonna find those whales  . Anyway, that looks like a nice build.. but, what about the component side of that board, is it protected? Oh, I noticed something, the components on the end of the board, the caps, they are bent in is that so that they can safely sit on the switch or what?

I just use electrical tape to cover the board.. I suppose the top side of the board could short but this has never happened to me, and I've never done anything about it. I'm also considering using clear nail polish on the solder side, but if a component ever goes bad, it becomes annoying to desolder stuff, etc.

I also prefer to have the component side showing. I don't know why. I just like it better that way

Electrical tape was what I originally considered doing, seems easiest, and easy to remove for debugging etc. Maybe you could cover the lid of the case with something like electrical tape or foam to prevent the top side from shorting. I was also thinking, if the component side is showing, is there danger of the components banging against the lid when you move the box around?

Thanks for the help. Everything is appreciated.

[tehfunk]

  Pretty much anything you think will work will work, IME>
  Just so you know I'm known as 'unorthodox' from time to time, and push the quickness of board mounting to utilize the 'free and available' to cause it to be done 'now.
  As long as you don't use conductive materials...
  Foam, EZ, quick, good, ugly until the coffin is sealed [hopefully no-one ever has to see]. It's the packing material that comes in boxes, a 'plastic-ey-styrofoam], it's possible to cut sheet with shears, I go around the outside, then cut the center ~flat, and make room for tall caps.
  Plastic sheet, heavy duty theft preventer type, shears required to open product, cut precisely just a little wide, clamps itself in the box.
  Makes a fine 'mounting sandwich', insulating HD plastic sheet across the substrate between the walls [or bend a side and have the plastic go up the wall[s also], foam fit to clamp lightly on top/
  I do like some fitted foam under the board bottom because I perfboard and clamping too hard can bend a wire-trace to mis-connect.   
 

I am sorry pete, that was a really confusing post, maybe could you explain it to me a little bit clearer? I'd like to know because I'm sure they work well if you have been making boxes for a very long time. 

You could use an old plastic bag, cardboard, cut up old plastic bottles...

Many options that don't require buying any new products.

I am digging that plastic bag idea, I could encapsulate the board and all. I know you can use cardboard, it's just as I said, that I wanna know how you do it, because I am sure I could come up with some way of doing it wrong. If you cant tell, I have a lack of confidence with my instincts in building.

[bkanber]

If you cant tell, I have a lack of confidence with my instincts in building.

Be confident about your instincts. There's really little you can do to totally ruin a build after the board's in the box. Even shorting components probably won't kill anything at the low voltages and powers we use for pedals (I emphasize probably because, well, there's always a chance).

I literally just cover the bottom of the board with electrical tape. If I feel theres a chance of the tip pin of the jack touching the box, I cover that in tape too. If I feel like theres a chance of something shorting against the back of the pots, I cover them with tape too.

And if your components are soldered down nicely, there's little chance shaking the box around will knock them loose or damage them. But, if you feel that's a possibility, cover them in tape too!

Tape, plastic bags, foam, clear nail polish. It all works, it's just a matter of taste and what you have on-hand.

Be confident, and go with your gut. If it doesn't conduct, it's good.

One thing to be wary of: I once built a headphone amp inside a cigarette pack. The thing kept on shorting, and it took me 20 minutes to figure out why. Turns out I left the cigarette pack paper-gold-foil stuff inside.. it's not very conductive, but it's enough to short out the solder side. Even with 20 minutes of continuous shorting before I figured it out, nothing was permanently damaged.

So don't worry about what you can and can't use. Usually, problems can be fixed before they become permanent.

[bumblebee]

Electrical tape was what I originally considered doing, seems easiest, and easy to remove for debugging etc. Maybe you could cover the lid of the case with something like electrical tape

i cover the lid in tape if the electros are going to touch it.
you could always adapt the layout for axial electros so this isnt a problem but tapes good imo.
anythings good so long as components/trace dont touch the case i spose.

[toneman]

Just make some standoffs and/or spacers out hotmelt glue.

If U are using perfboard, squeeze the HMG thru the holes and they will "grab" the glue.

To get a bond on aluminum or plastic boxes, rough up the surface where U want the glue to go.
Use a coarse sandpaper like 80grit.  Clean the residue away, with a brush.  Avoid blowing on
the surface as U add moisture.  Aviod touching as U transfer skin oils.

Add the HMG to the area in "dol-ups". Should kinda look like a hersey kiss blob.  Make sure it sticks after cooling.
Then put board over same blobs with fresh HMG sticking to the old HMG.
It's effective and works for a long time.
Can also be used to "strain relief"  any plug connectors to keep them from vibrating loose.

Keep on building....
afn
T

[tehfunk]

Here's what I think I am going to do...
1. Cut up a plastic bag, probably get rid of "zipper" and tape it up so it loosely fits around the board like a folder and does not stress the wire connections.
Like this :  |__| . with open part for wires.
I think this will suppress any of my fears of the component side of the board shorting.. but typical plastic bag material will most likely be punctured by the solder joints. so...

2. Put the board in so the solder joints face up when the box is opened. Cover the lid of the box with electrical tape. This will prevent the solder sie from shorting. This could be done with non conductive foam and many other materials.

I think this will work well because it offers easy debugging (just remove the little bag) , whereas adhesive requires a lot more work if anything needs to be changed. And, minimal space.  Lastly, as was the goal of this all, it requires very little work, no epoxy, and saves space.

Thanks for all the advice I really appreciated it. And, please, let me know what you think of the method I outlined above. Do you think it will work well?

[R.G.]

There is a reason that boards are tied down, held firmly in place.

==> A firmly mounted board is more reliable overall. <==

Unless you have a really really good reason for leaving your board waffling around inside a box with the sharp leads and pointy ends of solder joints cutting through whatever you  insulate with, it's hard to justify not tying a board into place so it doesn't short out.

[Paul Perry (Frostwave)]

Gaffa.
As for a "loose" board, it doesn't increase reliability! Eventually, if a wire is flexed enough, it's going to break.
And the electrolytic question, I've seen some large caps where one side connected to teh case, don't know if the little ones are like that. Wouldn't take a chance on it.

[ClinchFX]

I mount PCBs without needing screws through the box, by making a thin metal mounting bracket with a hole that fits on the pot thread.  I attach the PCB to this bracket.  I do this not only for reliability, but also as a matter of personal pride in my build.  IMO, floating PCBs are not cool.

Peter.

[tehfunk]

There is a reason that boards are tied down, held firmly in place.

==> A firmly mounted board is more reliable overall. <==

Unless you have a really really good reason for leaving your board waffling around inside a box with the sharp leads and pointy ends of solder joints cutting through whatever you  insulate with, it's hard to justify not tying a board into place so it doesn't short out.

Actually, I used the velcro method on your website to do my first project, which I recently completed.. And, I wanted to fit my future builds into smaller boxes, so the floating board seemed like the logical way to save space. And, I was skeptical of how floating board kept from shorting I read up on it, and created this thread in order to find out more ways of doing it, and to try to create a reliable method of doing it. Of course, it will not be as reliable as mounting. Am I at least right that it will save space?

Gaffa.
As for a "loose" board, it doesn't increase reliability! Eventually, if a wire is flexed enough, it's going to break.
And the electrolytic question, I've seen some large caps where one side connected to teh case, don't know if the little ones are like that. Wouldn't take a chance on it.

what is gaffa?
I think you misunderstood, I didn't say it increased reliability, I was saying I wanted to find a reliable way of doing a "loose" board. About the electrolytic, you didn't say wehter the large caps connected to the case caused a short?

I mount PCBs without needing screws through the box, by making a thin metal mounting bracket with a hole that fits on the pot thread.  I attach the PCB to this bracket.  I do this not only for reliability, but also as a matter of personal pride in my build.  IMO, floating PCBs are not cool.

Peter.

I wasn't saying I needed screws through the box, I am simply asking about ways to not mount the board to the case or pots in any way, but to leave it floating and be reliable. BTW, what did you mean by on the pot thread, do you mean the back of the pot?

[ClinchFX]

I wasn't saying I needed screws through the box, I am simply asking about ways to not mount the board to the case or pots in any way, but to leave it floating and be reliable. BTW, what did you mean by on the pot thread, do you mean the back of the pot?

The thread is the part of the pot that you put through the hole in the box and screw the nut down on.  I sandwich the bracket between the pot and the box.  I'll post a photo later.

Peter,