Attaching a PCB to a box with risers

[Skippy]

So I'm replacing a PCB in a plastic box. Currently the PCB is attached to the box by some risers- there are holes in the PCB, which you put screws through, which attach to plastic risers moulded to the base of the case.  The trouble is that my new PCB has different dimensions from the old one- I can cut the old risers off no bother, but how do I attach some new ones to the bottom of the case to fit the holes in the new PCBs? I'd quite like to do it without marking the outside of the box at all.

Any suggestions?

[dr_p]

A+B=epoxy

[edpalmer42]

Instead of attaching the risers to the plastic box, attach them to another flat piece of plastic or metal.  This other piece could be small pieces maybe one cm. square for each riser or it could be one piece the size of the PCB.  The size would depend on how heavy the PCB is and how much banging around it's going to experience.  Then use double-sided foam-core tape to attach this to the inside of the plastic box.  Make sure you've got it right because you'll have an awful time getting it out if you make a mistake!

Ed

[bookaboo]

Make a mounting plate

Get some FR4 (or anything suitable), cut to size of the original PCB and drill the mounting holes for the original box.
Then drill holes and fit spacers to suit the new PCB.

[Skippy]

Some good ideas here.

I bought some of these http://uk.rs-online.com/web/c/pcb-prototyping/pcb-spacers-pillars-supports/adhesive-backed-supports/

but I am already regretting it as it turns out my replacement board hasn't got any holes at all, and I can't really drill any.

Many thanks for the idea of mounting it on something that has got the right sized holes though. Time for some 

[SeanB]

3M double sided foam tape...........

[G7PSK]

Some of this stuff, careful use the wrong one and you will never get it apart again, I have stuck 1.5 mm steel sheet with the stuff and tried to pull it apart and the steel tore.

http://www.vikingtapes.co.uk/c-88-indoor-double-sided-foam-tapes.aspx?gclid=CKeVj72vtLYCFcHHtAodu3QAOA