Conductive foam quality is not up to standard? Did you use all of these tests correctly?

Conductive foam is the conductive sleeve wound on the foam core made of polyurethane or EPDM, conductive sleeve is usually composed of silver plated nickel nylon, aluminum or Monel wire (nickel copper alloy) Ferrex (tin-coated copper wire), has good electrical conductivity. In line with the flame retardant grade (UL94-V0), with good elasticity and flexibility and other mechanical properties.

Conductive foam has good shielding performance, when encountering radio waves, it will reflect, absorb and provide good shielding effect according to the nature of its object. The conductive cloth is wrapped on the flame retardant sponge, and after a series of treatments, the conductive foam has good surface conductivity, and it can be easily fixed on the device to be shielded with adhesive tape. Foam shielding materials are available in different profile shapes, installation methods, UL grades and shielding effectiveness.

Conductive foam has the following advantages:

When the frequency is 20MHz-10GHz, the shielding efficiency is >100dB

The surface resistivity is low, <0.07 ohms/square, making the fabric has excellent electrical conductivity

Good wear resistance, frequent use does not affect the actual shielding function

Works well over a relatively wide temperature range (-35 ° C to 75 ° C)

Good flame retardant, through UL certification up to UL94-VO or UL94-HB

Electrochemical compatibility between substrates can be ensured to a large extent by selecting appropriate coated fabrics

Conductive foam is especially suitable for occasions with limited capacity and closing pressure, and the cost is low, and it is especially suitable for use in the occasions requiring high performance shielding with good fit, and can be widely used in electronic chassis, chassis, indoor chassis, industrial equipment, notebook computers, mobile communication equipment, etc.

Conductive foam is so useful, in the face of various products on the market, how should we choose? How to determine whether the conductive foam is qualified? Below we summarize some methods of detecting conductive foam:

Appearance requirement

Conductive cloth or aluminum foil cloth surface is smooth, no damage; No visible crease on the surface, no defects

Cut all around neatly, no off-line phenomenon

Gently pinch the conductive foam with your hand and compress it to about 2/3 of its height or thickness, there is no separation between the sponge and the conductive cloth (aluminum foil cloth)

Undesirable phenomenon

Foam adhesive requirements

Usually, the double-sided adhesive pasted by the conductive foam with punching holes in the middle is conductive adhesive, and the one without opening holes is generally selected according to customer requirements of ordinary double-sided adhesive or conductive double-sided adhesive

Double-sided tape must meet customer's adhesive requirements

The surface of the pasted double-sided tape must be flat, without folds and lack of glue

The base adhesive is flat and uniform conductive foam

Electrical conductivity requirements

Requirements: The resistance value of the conductive adhesive should be less than or equal to 60 milliohm

Materials required: Scissors, horizontal copper block, surface resistance tester

Step 1: Randomly sample the conductive foam to be tested and cut out the corresponding size (46mm*26mm) according to the measurement specification.

Step 2: Place the cut material on a horizontal table and place the horizontal copper block on top of the sample

Step 3: Turn on the power switch of the surface resistance tester, and press ZERO to zero the connection of the resistance measuring clamp

Step 4: Add 1KG insulator to the test sample, connect the resistance measurement clips on both sides of the horizontal copper block, and record the displayed resistance value

Conductive foam with rubber sponge:

Appearance requirement

The surface of the product is neat, uniform, no dust, and there is no hole on the surface (the size of a single hole cannot exceed 1mm, and the number is differentiated according to the size of the specific product).

Cut all around neatly, no imperfections

Double-sided adhesive backing paper complete, no damage, the product is easy to peel

The foam is uniform and the product gap is small

Sponge back rubber requirements

Double-sided tape and sponge paste firmly, peeling by hand without stratification

Double-sided tape must meet customer's adhesive requirements

The surface of the pasted double-sided tape shall be flat, without folds and lack of glue

Other quality requirements

The flame retardant grade meets the requirements

Temperature resistance: -20℃ to 100℃, the sponge does not deform, does not zoom, discoloration