VERWENDUNG EINES SILICONHARZES ZUM BESCHICHTEN EINES SUBSTRATS

Lacquer is obtd. by (i) precondensation of: (a) 1-10 mol.% and at least one Si-cpd. of formula (SiR4 (I): (R = halogen, hydroxy, alkoxy, acyloxy or a chelated ligand); (b) 20-94 mol.% of at least one organic silane of formula (R''m(R'''Y)nSiX(4-m-n) (II): (R'' = alkyl, alkenyl, aryl, alkylaryl, arylalkyl, alkenylary, or arylalkenyl; R''' = alkylene, alkenylene, arylene, alkyl-arylene, aryl-alkylene, alkenyl-arylene or aryl-alkenylene; R'' and R''' may be optionally interrupted by -O-, -S or -NH-; X = H, halogen, hydroxy, alkoxy, acyloxy, -NR'2; R' = H or alkyl; Y = a polymersiable gp.; m, n = 0-3; and m+n = 1-3 and (c) 5-30 mol.% of at least one organic silane of formula R''pSiX4-p (III): (p = 1, 2 or 3; and optionally (d) 0.01 mol.% of at least one reaction medium sol., lowv-volatility oxide of a metal from Gp. Ia-Va or sub Gps. IVb or Vb or a cpd. of these elements that forms a low-volatility oxide. Precondensation takes place pref. in the absence of water, opt. in the presence of an organic solvent, at 0-90 deg. C for 0.5-48 hr.; and (ii) hydrolysis condensation of the precondensate of step (i) at 0-100 deg. C for 1-72 hrs.. Also claimed are (1) a coating process comprising applying the above lacquer to a substrate and curing the lacquer; (2) coated substrates; and (3) the use of the lacquer for coating thin film capacitors. USE/ADVANTAGE - Used to coat printed circuit boards; thin-film capacitors, multiple-chip modules, optical components, resistors or intergrated circuits, optionally encapsulated, which are mounted on a circuit board; and Si wafers (all claimed). The lacquer has good adhesion to various substrates, it is thermally stable at up to 300 deg. C on Al and withstands immersion for 30 sec. in a molten solder bath at 280 deg. C without cracking. It has a very low content of alkali, which causes corrosion, it resists commonly used industral solvents and dertergents, and it has a very long shelf life (more than 200 days). The viscosity can be adapted eas ily for dip coating processes.