Conductive adhesive is a special adhesive, mainly composed of resin and conductive filler (such as silver, gold, copper, nickel, tin and alloys, carbon powder, graphite, etc.), which can be used for bonding in microelectronic components and packaging manufacturing processes materials.
There are many types of conductive adhesives. According to different conductive particles, conductive adhesives can be divided into metal (gold, silver, copper, aluminum, zinc, iron, nickel powder)-based and carbon-based conductive adhesives. Among the above conductive adhesives, the conductive adhesive synthesized by silver powder has excellent conductivity, adhesiveness and chemical stability, it will hardly be oxidized in the adhesive layer, and the oxidation rate in the air is also very slow even if it is oxidized , the generated silver oxide still has good conductivity. Therefore, in the market, especially in electrical devices with high reliability requirements, conductive adhesives with silver powder as conductive fillers are the most widely used. In the choice of matrix resin, epoxy resin has become the first choice because of its high content of active groups, high cohesive strength, good adhesion, excellent mechanical properties, and excellent blending properties.
When silver powder is added to epoxy adhesive as a conductive filler, its conductive mechanism is the contact between silver powders. Before the conductive adhesive is cured and dried, the silver powder in the epoxy adhesive exists independently and does not show continuous contact with each other, but is in a non-conductive and insulating state. After curing and drying, as a result of the curing of the system, the silver powders are linked to each other in a chain shape to form a conductive network, showing conductivity. After adding silver powder to the epoxy adhesive with good performance (the amount of toughening agent and curing agent are 10% and 7% of the epoxy resin mass, respectively), the performance is tested after curing. According to the experimental data, as the filling amount of silver in the conductive adhesive increases, the volume resistivity decreases significantly. This is because when the silver powder content is too small, the amount of resin in the system is much more than that of conductive filler silver powder, and the silver powder is difficult to contact to form an effective conductive network, thus shows a higher resistance. With the increase of the silver powder filling amount, the decrease of the resin increases the contact of the silver powder, which is beneficial to the formation of the conductive network and reduces the volume resistivity. When the filling amount is 80%, the volume resistivity is 0.9×10-4Ω•cm, which has good conductivity, FYI.
Silver powders with adjustable particle size(from 20nm-10um), different shapes(spherical, near-spherical, flake) and customized service for density, SSA, etc. are available.
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