Plastic Cavity Electroplated?

Dr. Karumudi and Kevin, I want your opinions on something – Do you think a plastic cavity electroplated with copper will work?  Here is why I ask:

  1. Cost –Motive Industries in Calgary is a company that designs and builds concept cars and they recently purchased an FDM machine.  They are willing to print the part in ABS plastic (specs attached) for just over $800 for the entire cavity.  I would then spray the plastic with a conductive paint, then have it electroplated with a kit like this.
  2. Microwave Skin Effect – Because of the high frequency nature of the microwaves, they only need 1 millimeter or less, right?

My only concern is heat – if the cavity gets hot, it will melt the plastic.  However this might not be a problem because:

  1. If the plastic melts or browns, we can tell where the cavity is getting hot.
  2. We can make sure the electroplating is extra thick, say a couple mm, and even if the plastic melts or burns away, the copper will still hold it’s shape.

The plan is to split the cavity in two, add bolt holes around the outside, mounts for the probes and for the tuning mechanism.  Here is the basic model I am starting with:

Here are the benefits of using a 3D printing method over brazing copper sheeting together:

  • Accuracy – easily within 0.010″ or better
  • Reproducible – We can offer to build these cavities for other people who may want to duplicate our results
  • Fast – The mounts for the probes and the tuning mechanism at the back will be built at the same time as the cavity is printed
  • Weight – a plastic cavity plus copper plating will weigh less then a pure copper cavity

Using Motive’s FDM machine is by far the cheapest method of fabrication I have found besides trying to braze copper sheeting together myself.  They have also been very responsive.

I have also been contacting vendors all morning about copper plating the plastic because if it is inexpensive enough, I would rather pay someone else to do it.