| The use of conductive epoxies in the electronic | | | | Most common two part electrically conductive |
| industry is becoming more and more common as | | | | epoxies are used for component attachment, |
| the number of new epoxy systems on the | | | | termination and other applications in hybrid circuits, |
| market increases. Epoxies filled with nickel, carbon | | | | membrane keypads and other electromechanical |
| and silver are used for chip bonding, die | | | | assemblies. |
| attachment and many other applications. Silver | | | | The thixotropic properties and non-stringing |
| filled epoxy presents best conductivity but is also | | | | characteristics make them ideal materials for |
| most expensive. | | | | high-speed, dot dispense processes where low |
| In 1966, Epoxy Technology was the first | | | | temperature curing is required. They allow |
| company to promote silver-filled epoxy resins as | | | | automated dot dispense processes to run up to |
| die-attach materials. Prior to this time, all dice | | | | 70% faster. This is attributed to their low |
| were bonded to metal or ceramic substrates by | | | | viscosity and non-stringing characteristics. |
| means of eutectic alloys. | | | | They exhibit very good adhesion to most metal |
| Most (more than 90%) of the electrically | | | | and plastic substrates, have good temperature |
| conductive adhesives for die bonding are isotropic | | | | resistance, toughness, and allow for differences in |
| materials that conduct electricity in the in-plane | | | | coefficients of thermal expansion between two |
| and out-of-plane directions. Electrically and | | | | bonded substrates. |
| thermally conductive adhesives are available in the | | | | Convenient mix ratios and packaging in |
| form of thixotropic plates or films. | | | | pre-weighed amounts allow for ease of use in |
| Paste silver-filled epoxies are available either as | | | | fast paced production environments. Most are also |
| two-part materials that have to be mixed, or as | | | | available in due, pre-weighed and sealed plastic |
| one-part compositions premixed, degassed, and | | | | pouches, or pre-mixed and frozen in syringes. |
| frozen in small syringes. Both are designed to | | | | Some silver-filled electrically conductive epoxy can |
| have optimum flow properties when dispensed by | | | | be modified on the cure speed, working time, or |
| screen printing, stamping, or with automatic | | | | rheology which makes them more compatible |
| dispensing machines. | | | | with many unique manufacturing process. |
| >> Applications and Advantages | | | | |