The present disclosure relates to a dielectric substrate that may include a polyimide layer and a first filled polymer layer overlying the polyimide layer. The first filled polymer layer may include a resin matrix component, and a first ceramic filler component. The first ceramic filler component may include a first filler material. The first filler material may further have a mean particle size of at not greater than about 10 microns.

An object of the present invention is to provide an electrically conductive paste and a sintered body thereof having a low electric resistance value and excellent electrical conductivity when made into a sintered body. An electrically conductive paste comprising: a flake-like silver powder having a median diameter D50 of 15 μm or less; a silver powder having a median diameter D50 of 25 μm or more; and a solvent, wherein the content of the flake-like silver powder is 15 to 70 parts by mass and the content of the silver powder having a median diameter D50 of 25 μm or more is 30 to 85 parts by mass based on 100 parts by mass in total of the flake-like silver powder and the silver powder having a median diameter D50 of 25 μm or more.

A circuit forming method, comprising: a coating step of applying a metal-containing liquid and a metal paste in an overlapping manner on a base, the metal-containing liquid containing fine metal particles and the metal paste containing a resin binder and metal particles larger than the fine metal particles in the metal-containing liquid; and a heating step of making the metal-containing liquid and the metal paste coated in the coating step conductive by heating the metal-containing liquid and the metal paste.

A resin composition contains a thermosetting resin (A) and an inorganic filler (B). The inorganic filler (B) includes: a first filler (B1); and a second filler (B2) of a nanometer scale having a smaller particle size than the first filler (B1). The first filler (B1) includes an anhydrous magnesium carbonate filler (b1) and an alumina filler (b2). The proportion of the first filler (B1) relative to a total solid content in the resin composition is equal to or greater than 50% by volume and equal to or less than 90% by volume. The proportion of the second filler (B2) relative to the total solid content in the resin composition is equal to or greater than 0.1% by volume and equal to or less than 2.0% by volume.

A metal-clad laminate includes: an insulating layer; and a metal layer stacked on the insulating layer. The insulating layer includes: a first layer; and a second layer interposed between the first layer and the metal layer. The first layer contains a cured product of a first resin composition containing composite particles. The second layer contains a cured product of a second resin composition. The first resin composition contains composite particles, each having a core containing a fluororesin and a shell containing a silicon oxide that coats the core at least partially. The second resin composition may or may not contain composite particles. When the second resin composition contains the composite particles, a ratio of the composite particles in the second resin composition to solid content of the second resin composition is lower than a ratio of the composite particles in the first resin composition to solid content of the first resin composition.

A metal-clad laminate includes: an insulating layer; and a metal layer stacked on the insulating layer. The insulating layer includes: a first layer; and a second layer interposed between the first layer and the metal layer. The first layer contains a cured product of a first resin composition containing composite particles. The second layer contains a cured product of a second resin composition. The first resin composition contains composite particles, each having a core containing a fluororesin and a shell containing a silicon oxide that coats the core at least partially. The second resin composition may or may not contain composite particles. When the second resin composition contains the composite particles, a ratio of the composite particles in the second resin composition to solid content of the second resin composition is lower than a ratio of the composite particles in the first resin composition to solid content of the first resin composition.

An organic board of the present disclosure has a resin component comprising at least one resin selected from the group consisting of an epoxy resin, a polyimide resin, a phenolic resin, an amino resin, a polyester resin, a polyphenylene resin, a cyclic olefin resin, and a Teflon (registered trademark) resin as the main component, and a non-resin component including at least one of an inorganic filler and a flame retardant, in which the non-resin component is dispersed in the resin component, at least a part of the non-resin component is agglomerated to form an aggregate, a part of the resin component forms a resin material part having a particle shape, the resin material part exists within the aggregate, or the resin component forms a matrix phase surrounding the aggregate, and there are voids at some interfaces between the resin component and the aggregate.

The present disclosure relates to a dielectric substrate that may include a polyimide layer and a first filled polymer layer overlying the polyimide layer. The first filled polymer layer may include a resin matrix component, and a first ceramic filler component. The first ceramic filler component may include a first filler material. The first filler material may further have a mean particle size of at not greater than about 10 microns.

The present disclosure relates to a dielectric substrate that may include a polymer based core film, and a fluoropolymer based adhesive layer. The polymer based core film may include a resin matrix component, and a ceramic filler component. The ceramic filler component may include a first filler material. The particle size distribution of the first filler material may have a D.sub.10 of at least about 1.0 microns and not greater than about 1.7, a D.sub.50 of at least about 1.0 microns and not greater than about 3.5 microns, and a D.sub.90 of at least about 2.7 microns and not greater than about 6 microns.

The wiring board according to the present disclosure includes: a first insulating layer including insulating particles; a plurality of first conductors located on the first insulating layer at an interval of a first distance from each other; a second conductor located on the first insulating layer at an interval of a second distance from the first conductor; and a second insulating layer located on the first insulating layer to cover the first conductor and the second conductors and including the insulating particles. When a boundary portion between the first insulating layer and the second insulating layer is viewed in cross-section in the thickness direction, the ratio of a first area occupied by the insulating particles in a first boundary portion including the first distance is higher than the ratio of a second area occupied by the insulating particles in a second boundary portion including the second distance.