Printable compositions, and their application to dielectric surfaces used in the manufacture of printed circuit boards

A composition for application to a dielectric substrate a predetermined pattern and comprising, in admixture

• (i) a metallic powder component which includes (a) a solder powder and (b) a metal powder melting at a higher temperature than the solder powder,
• (ii) a polycarboxyl compound effective as a fluxing agent for the metallic powder component at a first elevated temperature and as a cross-linking agent for an epoxy resin at a higher second temperature, the polycarboxyl compound being selected from carboxylated polymers, polycarboxylic acids as such and polymer fatty acids providing multiple reaction sites which lack chemical protection, and
• (iii) an epoxy resin, which composition is at a temperature below said first elevated temperature.

A composition comprising in admixture:

• (i) a metallic powder component which includes (a) a solder powder and (b) a metal powder melting at a higher temperature than the solder powder;
• (ii) a polycarboxyl compound effective as a fluxing agent for the metallic powder component at a first elevated temperature and as a cross-linking agent for an epoxy resin at a higher second temperature, the polycarboxyl compound being selected from carboxylated polymers, polycarboxylic acids as such and polymer fatty acids providing multiple reaction sites which lack chemical protection, the composition being applied to a dielectric substrate to which an epoxy resin has been pre-applied, the composition thus applied being at a temperature below said first elevated temperature.