SST -3PM4

(40% penyl- 45% methylsilsesquioxane)-(5% phenylmethylsiloxane) (10% diphenylsiloxane) tetrapolymer. This T-resin is an alternate designation which indicates that there are three (tri-substituted) oxygens substituting the silicon. SST -3PM4 is a highly cross-linked material with empirical formula RSiO_1.5. . It is named from the organic group as well as its one and half (sesqui) stoichiometry of oxygen is bound to silicon. Polysilsesquioxane resins containing silanols (hydroxyls) can be cured at elevated temperatures. Its formulation and catalysis is generally performed at room-temperature or below. The condensation of silanols leads to cure and the resins become tough binders or films. The cure is usually accelerated by the addition of 0.1-0.5% of a catalyst such as dibutyltindiacetate, zinc acetate or zinc 2-ethylhexanoate. This resin as dielectric, planarization and reactive ion etch resistant layers finds application in microelectronics. It is also used in encapsulants and sealants.