Materials system for low cost, non wire-wound, miniature, multilayer magnetic circuit components

Abstract

This invention describes materials system and processing conditions for manufacturing magnetic circuit components such as induction coils and transformers that are non wire-wound, miniature in size and, have a low manufacturing cost. The materials system of this invention is comprised of: (1) Low Temperature Cofire Ceramic (LTCC) tapes or thick film pastes of ferromagnetic ceramics with a 20 to 750 range of magnetic permeability to form the magnetic core of the components, (2) Thick film buried silver conductor paste to form the planar induction coils on individual magnetic layers, (3) Thick film via-fill silver conductor paste to interconnect two or more of the planar induction coils through the thickness of the magnetic layers, (4) Thick film silver solderable top layer conductor paste compatible with the ferrite and, (5) Thick film dielectric paste with low magnetic permeability to redirect the magnetic flux for enhancing the magnetic coupling coefficient and to insulate the silver conductors for enhancing the dielectric breakdown voltage. The key characteristics of the materials system of this invention that facilitate manufacture of low cost non wire-wound, miniature magnetic circuit components are: (1) Mutual compatibility essential for either of the techniques, the cofire technique or the sequential technique, used for manufacturing multilayer hybrid microelectronic components, (2) Complementary thermo-physical properties such as shrinkage and thermal expansion coefficient essential for manufacturing flat multilayer magnetic components, (3) Magnetic components with magnetic coupling coefficients greater than 0.95 under optimal processing conditions and, (4) Magnetic components with dielectric breakdown voltage greater than 500V/mil under optimal processing conditions.

Dependencies are inferred from the claim text.