hi-temp platable plastic

[Keveo]

Hello all,

I looking for a platable plastic thats capable of 125c. Unfortunately, PC/ABS blends are boarderline. Can any one recommend a high-temp platable plastic that is easily capable of 125c.

 

[patprimmer]

Glass filled nylon is theoretically palatable, but I never saw anyone successfully commercialise it.

Glass filled PC/ABS might do, but the glass will give a poor finish and may induce stress that will be attacked preferentially in the plating pre-treatment solutions.

Are you plating for performance or for looks.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Keveo]

thanks for the response, the application is for performance only, acting as a standoff between two pcb's and to provide rfi/emi protection as well.

 

[patprimmer]

There are conductive polymers about for that, including conductive carbon black and stainless steel fibre filled materials. SS filled PC should do the job. It is fairly expensive but cuts out the plating process. PC or GF nylon could also be painted with conductive paint.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Keveo]

Thanks for your input....the underside of the shield however, cannot be conductive, thus plating or painting one side would be a good solution....i'll look into the conductive paint...thanks again

 

[MikeHalloran]

I'll save you a bunch of time and aggravation here.

Plated plastic and conductive paint don't work reliably for shielding....

... not because they're not adequately conductive, but because you can't produce and maintain a reliable ground connection to the conductive film.



Mike Halloran
Pembroke Pines, FL, USA

 

[Keveo]

Thanks Mike,

However, why is the ground connection unreliable. I would have a ring terminal screwed directly on the board thru the shield sandwiching the PCB conductive pad to the conductive side of the shield. You must know something I dont...can you please go into detail. Thanks...

 

[Keveo]

ah sorry......the ground would most likely go thru the board to the conductive pad and not thru a ring terminal........sorry...mechanical guy working on a pcb here...

 

[patprimmer]

If you moulded in a brass insert then plated over the plastic and the insert.

Once you have your coating of electro less nickel or electro less copper, you can build up with any metal that can be applied by electroplating of metal to any thickness you like, so long as you are prepared to pay the price.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MikeHalloran]

For starters, a screw can ground exactly one point on a sheet of conductive film. Unfortunately, effective shielding requires quasi- continuous contact all around the periphery of the shielded area, e.g. a row of screws... and they have to get closer together as the working frequency goes up.

Eventually, you end up with nickel plated steel rimmed with rows of closely spaced fingers that are in turn mechanically held in contact with a ground plane. Or containers closed by continuous solder seams or fusion welds.

All of these wonderful, cheap, easy, quick shielding methods work just fine in the engineering laboratory. Put them together with real line assemblers and expose them to the customer's real environment, and all the money you saved on wonderful, cheap, etc. goes out again, greatly magnified, as warranty costs.



Mike Halloran
Pembroke Pines, FL, USA