The resulting specific conductivity also has values closer to those of traditional solder alloys. Conductive adhesives with disappearing liquid phase use traditional surface mounting technology equipment for dosing and processing. Volumetric and boundary metallurgical electrical interconnections provide stable electrical and thermal conductivity. The process called transient liquid phase sintering (TLPS) forms a metallic mesh reinforced by the polymer matrix immediately at the point of formation. Some disadvantages of conventional conductive adhesives with particulate fillers are less pronounced in conductive vanishing liquid phase sintering adhesives, which have interpenetrating polymer/metal meshes. The addition of nanoparticles allows the formation of additional bridges between the particles, which can increase the density of the conductive mesh connections and reduce the overall resistance. The total circuit resistance is determined by the resistance of the scales and the contact resistance between them. Often conductive meshes in isotropic conductive adhesives are formed by silver flakes. Researchers at Endicott Interconnect Technologies have shown that the use of nanoparticle-filled adhesives made of copper, silver and fusible alloys when co-pressed can improve the interconnection density of component housings and printed circuit boards on organic substrates. Because of the tendency of nanoparticles to form clusters for practically applicable conductive adhesives based on them, their effective and uniform distribution plays a critical role. With the introduction of nanoscale fillers, electrical conductivity is increased through a combination of several mechanisms, including more efficient filler compaction and easy sintering of the particles to form a highly conductive mesh. The electrical conductivity of traditional conductive adhesives is limited by the contact resistance between the filler particles. curing ability (due to the large surface area).electrical conductivity (due to better sealing and sintering of the filler).cost (due to fewer precious metals in the composition).Nanotechnology has improved the performance of conductive adhesives in three different ways:

Electrically Conductive Adhesives Using NanoparticlesĪdvances in nanotechnology have led to a current revival in the field of conductive adhesives and other materials for making solderless connections. glass).ĭespite the advantages of conductive adhesives technology, their widespread use in the electronics industry has been limited due to lower specific conductivity than solders, low impact resistance and concerns about the long-term stability of electrical and mechanical properties.

compatibility with inexpensive non-solderable substrates (e.g.

easier processing (no flux residue cleaning).

higher flexibility and fatigue strength than solders.

ability to mount components with smaller lead spacing (anisotropic adhesives).

lower processing temperature requirements.

better environmental friendliness than lead-based solders.

Conductive adhesive fillers consist of metals such as gold, silver, copper and nickel, or nonmetals such as carbon.Īmong the advantages of conductive adhesives over traditional solder joints are: The polymers can be either reactoplastics (such as epoxies, polyimides, silicones and acrylic adhesives) or thermoplastics. Anisotropic conductive adhesives are suitable for small pin spacing, especially in the manufacture of flat panel displays, in surface mounting of small pin spacing components and in the mounting of Flip Chip components.Įlectrically conductive adhesives consist of a polymeric binder that provides mechanical strength and conductive fillers that give the material electrical conductivity. Typical volume concentrations of conductive fillers in such materials range from 5 to 10%. Anisotropic conductive adhesives only provide conductivity in the direction of the applied pressure during curing.

Isotropic conductive adhesives are mostly used in surface mount technology and hybrid assemblies. Isotropic materials conduct current in all directions and typically contain conductive fillers in volume concentrations of 20% to 35%. Although the electrical conductivity mechanisms of isotropic and anisotropic adhesives are different, both types of materials consist of a polymer matrix containing conductive fillers. There are two types of electrically conductive adhesives: isotropic and anisotropic. 10 Final Words Use of Conductive Adhesives Conventional Conductive AdhesivesĮlectrically conductive adhesives are a possible replacement for solder in microelectronic assemblies.

Soldering flux substitute