Лако-красочные материалы — производство

Silicone-based polymers have characteristics that make them desirable as the matrix of a conductive adhesive system. Their excellent thermal stability, low ionic impurity content, and especially, low modulus make silicones desirable for bonding very large die. A typical formulation would include linear polydiorganosiloxane oligomers with both vinyl and silicon hydride functionality, a platinum catalyst, an electrically conductive particulate, an adhesion promoter, reinforcing agents, and rheology modifiers [51]. The incorporation of sufficient silver flake to provide electrical conductivity will certainly increase the base polymer modulus and lower its elongation; however, from a mechanical property point of view, the silicones remain the primary choice for a low-stress die attach adhesive.

Reliability of the electrical properties of silicone-based isotropic adhesives has been the major difficulty to overcome and has essentially prevented commercialization. Another problem associated with silicones is that the addition polymerization reaction of silicones must be carefully controlled to prevent cure inhibition from various common chemical contaminants such as amines and sulfides. Other concerns include low-molecular-weight silicone polymer migration onto wirebond pads and very high CTE. There has been some activity in the development of hybrid resins that contain silicone blocks as comonomer with epoxies such that the epoxy processing can be maintained with the added stress reduction property of the silicones [52].