Metal-filled Polymers and Conductive Adhesives

by jasonwee

What are Metal-filled Polymers and why are they used?

The term polymer sometimes refer to plastics, but also encompasses a large class comprising of both natural and synthetic materials. Some natural materials are: shellac, amber, natural rubber and cellulose. There are many synthetic polymers consisting of  many types of plastics, man made rubbers, epoxies and resins. Some examples are synthetic rubber, Bakelite, neoprene, nylon, PVC, polystyrene, polyethylene, polypropylene, polyacrylonitrile, PVB, silicone.

A Metal-filled Polymer is: A polymer filled with metal particles such as Nickel, Copper, Graphite, Silver and other metals. Conductive Adhesives are a type of metal-filled polymer commonly used to repair or bind things to metal surfaces.  Both are widely used because of there unique properties. Metal-filled polymers’  mechanical properties and processing methods are typical of plastics but exhibit electrical characteristics similar to metals, due to the metals that are mixed in. As a result they can be compressed, shaped, hardened, softened, and more using temperature variance. Controlling these aspect allows for a wide range of applications.

Applications

Because of these properties, metal filled polymers and conductive adhesives are commonly used for rebuilding, repairing, protection, prevention, bonding, and sealing of metal objects (such as pipes, washing machines, etc). They also can serve as conductive inks, which can be used for printing circuits.

Metal filled polymers can effectively be used for surface mounting and other electronic component assemblies. Instead of using traditional soldering that contains lead, using conductive adhesives both increases the integrity of circuits and allows engineers to perform “cold” soldering. Nifty products such as LED glass are created by mounting surface LEDs onto glass using conductive adhesives and circuit printing.

There exist many suppliers of conductive adhesives and metal filled polymers (usually referred to as metal filled epoxies). The following lists a few of them:

  1. ITW Devcon – local corporation: 30 Endicott Street, Danvers MA 01923
  2. Hy-poxy – hy-­poxy-­systems.amazonwebstore.com
  3. Epoxies, Etc - http://www.epoxies.com/
  4. Cool Polymers - http://www.coolpolymers.com/eseries.asp
  5. Polysolder - http://www.cooksonsemi.com/products/polymer/polysolder.asp“

 

Safety

So I am going to write a little about the safety concerns when handling some of the metal-filled polymers and conductive powders we found.

With Plastic Steel (http://www.devcon.com/), a metal-filled epoxy used as a bond or sealant in the rapid repair of metal surfaces and equipment, it is a moderate skin irritant.  Contact at elevated temperatures can cause thermal burns, which may result in permanent damage. Extensive contact may also cause skin sensitization (itching, redness, rashes, hives, burning, swelling). It is best to handle this with no direct skin contact. The same applies to the other associated products in this class of materials, including Aluminum Putty Resin and Aluminum Liquid, Titanium Putty, Bronze Putty and FasMetal Alumina-filled Putty.

Plastic Steel has low vaporizations, but some of the other products in this class are toxic at sufficiently high concentrations, and maybe cause dizziness, headache and anesthetic effects, even trigger asthma-like symptoms in susceptible individuals. It is best to use these in a well-ventilated room, rather than in a completely closed environment.

Conductive metallic powders may cause irritation to the eyes, skin, and respiratory tract, as will metal-filled lacquers such as Cosmichrome (http://www.goldtouchinc.com/). In addition, powders at a sufficient powder-air concentration may ignite in the presence of a heat source. Care should be taken to avoid accumulations of dusts or powders in places where these accumulations could cause shorting of electrical switches, circuits or components

Uses in Art and Design:

Due to the wide range of applications there are some interesting uses of Metal-filled Polymers and conductive adheasives in art and design. MR Shock absorber are one example. MR Fluids are oily flids that when exposed to electric currents become viscus due to the electro manganic particles contained in the fluid. “Because the current can be turned on and off in milliseconds, the oily liquid transforms itself from a liquid to a solid and back again so instantaneously that is can significantly dampen shock from potholes, speed bumps or washboard roadways”  http://www.djc.com/news/ae/11151055.html.

EM Shielding is another interesting use in design. Du to excessive cell phone use, Ipods and other wireless devices, we are becoming increasing aware of and concerned by EW pollution. Conductive Polymers can function as shielding from these waves in elements like windows by coating them with a EM absorbing paste. PDF .

A third Example could possibly generate power though your shoes. Flexible generators or comprised partly by Metal-filled Polymers and have the ability to create energy when deformed. “Unlike traditional piezoelectric generators, which require quick, subtle motions to generate power, artificial muscles are better tailored to the “large, slow motions” we perform every day”. Ecouterre article.

Here is our PDF:

MetalFilledPolymers_ConductiveAdhesives