Electrically conductive adhesive

An electrically conductive adhesive is a glue that is primarily used for electronics.

The electric conductivity is caused by a component that makes ca. 80% of the total mass of an electrically conductive adhesive. This conductive component is suspended in a sticky component that holds the electrically conductive adhesive together. The particles of the conductive component are in contact to each other and in this way make electric current possible.

Composition

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The conductive component can be silver, nickel, copper or graphite. Other conductive materials are possible but unusual. The adhesive component can be a varnish, synthetic resin, or silicone. Variations in conductive component's type and concentration change the resistivity of the adhesive.[1] A typical silver-based conductive adhesive such as that made by Electrolube[2] contains ingredients in the following proportions:

Silver 30-60%
1-Ethoxypropan-2-ol 10-30%
Ethanol 10-30%
Acetone 5-10%
Ethyl acetate 1-5%

They are specifically formulated in paste (micro-particles)[3] for use in scanning electron microscopy (SEM) and other electron optical applications find use in producing or repairing printed circuit board (PCB) tracks, to paint-on an electrical screen, or to make electrical connections to non-solderable surfaces. [4]

Applications

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Conductive silver, SEM image. Visible width of picture is 434μm.
  • One could fix a defective conductor on a printed circuit board using an electrically conductive adhesive. In the same way, one could fix a defective rear windscreen heater on a car using an electrically conductive adhesive.
  • If just a small current is needed, a temperature-sensitive electronic element can be electrically connected to a circuit using an electrically conductive adhesive instead of soldering.
  • Electrically conductive adhesives can be used to paint the inner surface of plastic boxes containing electronic devices. This makes a Faraday cage saving the internal components from electromagnetic radiation.
  • Electrically conductive adhesives are used in SEM to fix and ground the sample to avoid electrostatic charging of the surface.

References

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  1. ^ "Master Bond Electrically Conductive Adhesives | MasterBond.com". www.masterbond.com. Retrieved 2018-05-07.
  2. ^ "Safety Data Sheet: Silver Conductive Paint | farnell.com" (PDF). www.farnell.com. Retrieved 2019-05-27.
  3. ^ "Silver Conductive Paste | antslab.in". www.antslab.in. Retrieved 2020-01-21.
  4. ^ "Silver Paste | americanelements.com". www.americanelements.com. Retrieved 2020-01-21.

Further reading

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  • A. Pizzi, K.L. Mittal (2003). Handbook of Adhesive Technology page 855ff . Marcel Dekker Inc. ISBN 0-8247-0986-1