Aluminum/polyester tape is most common and is applied during the cabling process. It is usually wrapped over the cable bundle with an un-insulated conductor, or drain wire, included as an option for easy shield termination. This shielding method is most cost effective since it is applied as part of the cabling process.
Aluminum/polyester tapes can be a applied with the aluminum side facing toward or away from the conductors. For electronic cables with only one group of wires to be shielded, it makes no difference electrically whether the aluminum side of the tape is facing the conductors or the cable jacket. Most common is the aluminum facing the conductors which allows easier inclusion of a drain wire as part of the cable bundle.
Where several groups of conductors are to be shielded, it is better to apply the tape with the polyester side out so that the possibility of random shield contacts is eliminated. Random shield contacts may complete ground loops and therefore may induce noise in adjacent circuits. Where guaranteed shield isolation is required, Kemcor uses an additional clear polyester tape over the aluminum/polyester tape as a second insulating barrier between shields.
A braided shield consists of many small copper wires braided over the cable bundle. Braided shields are also often applied over an un insulated conductor for ease of shield termination. A braid shield may be applied in conjunction with an aluminum/polyester tape shield for added shield performance. Braid shields are applied in an independent operation and therefore are more expensive than tape shields. Shield effectiveness is dependent on coverage. 85% to 95% coverage is common.
Spiral shields, or served shields, are composed of strands applied in one direction by using only the top carriers on the braider. There are no braided stitches - all strands are parallel. The main advantage of a spiral shield is its superior flexibility over braided shields.