Conductive Pad, ESD Pad, Conductive Adhesive – Cryogenic Exposure

SE65 is a carbon filled electrically conductive silicone rubber with a durometer of 65 on the Shore “A” scale. SE65 is typically used to dissipate or more specifically ground out static while providing some compliance and cushion. SE65 can be bonded to a conductive surface (aluminum or steel) using Stockwell’s RTV-60-CON which is also a carbon filled silicone based RTV (Room Temperature Vulcanizing). Bonding SE65 with RTV-CON makes a very intimate and strong bond when the surfaces are prepared properly.

Silicone has a general operating temperature ranging from -100 to 500°F (some grades vary). The SE65 has a conservative rating of -65 to 400°F. As a very crude test to see if there would be any deterioration of the SE65, RTV-60-CON or the bond between surfaces, a test piece bonded to aluminum was run thru Stockwell’s cryogenic deflasher, removed and hit with a hammer. The attached video clip shows the machine in idle mode set to -80°F (run mode). The sample was tumbled at -80°F for 60 seconds, removed and hit. There was no indication of bond or material degradation. This was a very crude test but does offer some insight to how well the bond holds up.

Stockwell Elastomerics carries a comprehensive line of ESD and EMI conductive silicone sheets, roll goods and molding compounds. For more information about these products, please call 215-335-3005 or email at service@stockwell.com.

THICK EMI GASKET & EMI GASKET OPTIONS

Stockwell Elastomerics provides custom EMI gaskets regularly for a wide range of customers. Each application is a bit different; some can be cut from “off the shelf” sheets of nickel graphite filled silicone and others may require special fluorosilicone compounds or silver plated particle filled silicone for more conductivity. Generally materials are .062” thick or thinner with a few conductive compounds available up to .125” thick. So what are the options for thicker EMI / NEMA seals? Below are a few pros and cons for different manufacturing techniques for EMI gaskets.

Option 1 – Mold the Gasket
Pros: You can control your design; sealing beads and 3 dimensional shapes are possible. Material savings; EMI compounds cost more that unfilled non-conductive compounds. Compression molding minimizes raw material waste.
Cons: Molds are more costly than tools used in die cutting, and molded parts have longer production lead times than die cut or water jet cut gaskets.

Option 2 – Mold Sheets and Water Jet Cut
Pros: If a part is smaller or there is little center waste, molding sheets from a standard sheet mold and then waterjet cutting the part geometry may be most feasible. This option offers flexibility in material thickness (.020” to .500”), conductive adhesive backings, and there is no tooling charge for the waterjet cutting process if a CAD file is provided. Lead times for this option are relatively short based on using our in-house 12” x 12” sheet tooling.
Cons: Geometries are limited to 2 dimensions and there is some edge and center waste.

Option 3 – Non-conductive sponge or foam with a bonded conductive wire mesh
Pros: This option offers another range of flexibility. Stockwell uses its core silicone foams and silicone sponge products (with or without adhesive backing) and bonds a Monel (Nickel/Copper alloy) wire mesh to the inside or outside edge of a gasket. This option offers lower compression forces, UL94 V0 foam option, closed cell sponges and a variety of thicknesses cut from standard, readily available roll or sheet stocks. Waste is less costly due to the non-conductive and expanded polymer. Lead time for smaller or initial volumes is relatively quick.
Cons: Geometries are limited to 2 dimensions. There is some assembly which may require scheduled shipments. Heavy compression and release cycles may disturb the mesh to polymer bond.

For more information about EMI gaskets, custom EMI gasket, silicone gaskets or other Stockwell products call 215-335-3005, email service@stockwell.com or visit our website at stockwell.com.