When manufacturing electrically conductive gaskets, usually an electrically conductive tape may be required. This allows for die-cut parts to have good electrical conductivity in all directions(isotropic, XYZ) throughout the part including the adhesive. These tapes provide the ability for the gasket to provide not only a continuous EMI shielding solution, but also an assembly solution by allowing an easy peel, and stick option to help in assemblies.
Types of ECATTS(Electrically Conductive Adhesive Tapes)
There are a few different variables/options when it comes to ECATTs. Adhesive thickness, type of adhesive, and type of filler. For many requirements, there is a tape to match. For example, for high-temperature requirements there is a silicone-based option(3M 9719 which is now discontinued as of April 2024). As another example, for high adhesion with great contact resistance, there is 3M 9707.
Below are some of the more popular options for electrically conductive transfer tapes available from 3M Company. As a 3M Converter, NEDC has access to a lot of the common/popular tapes for EMI Gasketing solutions.
Considerations when Selecting a Electrically Conductive Transfer Tape
There are a few considerations when considering an electrically conductive transfer tape.
1. What is the surface that is being adhered to?
There are many different surfaces that a tape can be adhered to, there could be an aluminum surface, or a plastic substrate such as polycarbonate. Its important to consider.
2. Not a popular consideration, but do you even need a electrically conductive PSA?
A lot of times, I see conductive PSA used when its not even necessary for EMI shielding. Is it needed for EMI shielding, or literally just an assembly aid?
3. Corrosion Resistance of dissimilar surfaces
It may be a good idea to consider what surfaces its going be against because corrosion resistance may be a concern overtime.
A note about adding conductive PSAs to EMI rubber gaskets:
When adding these adhesive tapes to conductive EMI gaskets, its important to note, they should not be for oriented wire, or perforated wire gaskets as the wires will break through under stress/strain anyways. Oftentimes when we see conductive adhesive tape, its on a conductive EMI/RFI gasket.
enclosure emi gasket
Tape Product #, thickness of adhesive, type of adhesive, type of filler, adhesion to stainless steel 24 hrs @ 72°F
3M 9703, 2mil, isotropic, acrylic-based, silver, 32 oz/in –
3M 9707, 2mil, isotropic, acrylic-based, silver, 55 oz/in –
3M 9713, 3.5mil, isotropic, acrylic-based, nickel/graphite, 50 oz/in –
3M 9719, 4mil, isotropic, silicone-based, nickel/graphite, 30 oz/in – discontinued
Difference Between Transfer Tapes, and Double Sided Tapes
One thing we wanted to highlight in this post was that there is a difference in double sided tapes, and transfer tapes. 3M manufactures, and sells a double-sided 9711S Tape. This tape has a PET carrier in the middle that is coated on both sides with electrically conductive adhesive. With transfer tapes, the tape comes off onto the substrate that will be shielded such as the gasketing, or other surface.
Lamination/Cutting of ECATTs to Gasket Materials
As an authorized 3M converter, we laminate many materials as we cut gaskets. Many of the electrically conductive gaskets that we manufacture require electrically conductive transfer tapes. Although silicone based adhesives are available, NEDC mostly utilizes acrylic-based adhesives for even fluorosilicone/silicone gaskets. The above tapes can be cut with laser-cutting if cut alone, and are normally cut through die-cutting/waterjet cutting if cut in gasket form.
More information on ECATTs(Electrically Conductive Adhesive Transfer Tapes)
For more information on Electrically Conductive Adhesive Transfer Tapes, or you believe you have an application that could utilize them please contact sales@nedc.com.