On 1/15/22 4:43 PM, Jeff Green wrote:
Posted from a Wendy's in Bardstown (it sucks).
Sorry for the false lead. As a commercial operation we bought a lot of the stuff.
There are other spray on emi shielding materials, I called our former ee and she told me the nickle based sprays are affordable and work pretty well. she also suggested tracking down real thin from a model store. Some is so as thing as tissue and can be formed by pressing in place, remove, use 3m spray adhesive which is available at loses, we used some to repair a section of wallpaper.
copper foil tape is readily available, has a conductive adhesive, and works quite well. It's available in a variety of widths.
Thin copper foil is also available - it's used by people making electric guitars and similar.? Some Scotch 77 or 74 spray adhesive and it's not coming off very easily.
The shielding effectiveness is tricky to estimate. Most leakage is from wires that penetrate the shielding (so your USB cable). Second would be leakage through slits or gaps in the shielding - you need the perimeter of the hole to be << 1/2 wavelength, so at HF, that's pretty easy.
At HF, the challenge is skin depth. The shielding needs to be > 5 skin depths.
Skin depth in copper at 1 MHz is about 2.5 mils (0.0025 inches, 64 microns), so your shield would need to be 12 mils thick, which is a lot of 1 mil thick tape.? On the other hand, 0.032 aluminum (20 ga) is pretty good.
is your friend.
One also needs to worry about magnetic fields, for which lossy ferrite material in an elastomer are useful.
When we get to our new home, and get set up, I'll try to find some spray on shielding available to the common man. Or former ee is in a move to Texas and will be really busy with a start up but will try to find an available spray.
I know nothing about 3D printers, so.....
Can you print with carbon laced plastic?
Is there conductive plastic for printing?
I had a moment to do a search (ever travel with 3 women?) and found this:
I have no idea if it's effective, others will have to make that judgement.
Mike C.
Clyde Lambert