Pastes are disclosed that are configured to coat a passage of a substrate. When the paste is sintered, the paste becomes electrically conductive so as to transmit electrical signals from a first end of the passage to ta second end of the passage that is opposite the first end of the passage. The metallized paste contains a lead-free glass frit, and has a coefficient of thermal expansion sufficiently matched to the substrate so as to avoid cracking of the sintered paste, the substrate, or both, during sintering.

A stretchable mounting board that includes a stretchable substrate having a main surface, a stretchable wiring disposed on the main surface of the stretchable substrate, a mounting electrode section electrically connected to the stretchable wiring, solder electrically connected to the mounting electrode section and including bismuth and tin, and an electronic component electrically connected to the mounting electrode section with the solder interposed therebetween. The mounting electrode section has a first electrode layer on a side thereof facing the stretchable wiring and which includes bismuth and tin, and a second electrode layer on a side thereof facing the solder and which includes bismuth and tin. A concentration of the bismuth in the first electrode layer is lower than a concentration of the bismuth in the second electrode layer.

Provided are a metal-base circuit board having excellent solder crack resistance, thermal conductivity, adhesive property, and insulation property and a resin composition for a circuit board used for the metal-base circuit board. A resin composition for a circuit board comprises a vinylsilyl group-containing polysiloxane (having a vinylsilyl group equivalent of 0.005 to 0.045 mol/kg) comprising (A) a dual-end type vinylsilyl group-containing polysiloxane having a weight average molecular weight of 30,000 to 80,000 and (B) a side-chain dual-end type vinylsilyl group-containing polysiloxane having a weight average molecular weight of 100,000 or more, a hydrosilyl group-containing polysiloxane (having a hydrosilyl group equivalent of 6 mol/kg or more), and an inorganic filler at 60 to 80% by volume. The mass ratio of (A) to (B), (A)/(B), is 80/20 to 30/70, and the molar ratio of (C) a hydrosilyl group to (D) a vinylsilyl group, (C)/(D), is 2.5 to 5.0.

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 printed wiring board includes a substrate and wiring provided on a surface of the substrate and including a cured conductive paste. The conductive paste contains metal nanoparticles having an average particle diameter of 30 nm or more and 600 nm or less, metal particles having an average particle diameter larger than that of the metal nanoparticles, a thermosetting resin having an oxirane ring in a molecule, a curing agent, and a cellulose resin. The wiring has a length of 100 mm or more and 1600 mm or less, a width of 0.3 mm or more and 3 mm or less, a thickness of 10 μm or more and 40 μm or less, and a resistance value of 1000 mΩ/m or less.

A printed circuit board includes a substrate and wiring provided on a surface of the substrate and including a cured conductive paste. The conductive paste contains metal nanoparticles having an average particle diameter of 30 nm or more and 600 nm or less, metal particles having an average particle diameter larger than that of the metal nanoparticles, a thermosetting resin having an oxirane ring in a molecule, a curing agent, and a cellulose resin. The wiring has a width of 0.3 mm or more and 6 mm or less, a thickness of 10 μm or more and 40 μm or less, and a resistance value of 500 mΩ/m or more and 5000 mΩ/m or less, and a welding strength of the electronic component to the substrate is 30 N 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.

Provided is a circuit board for reducing a likelihood of so-called through-hole disconnection, and enhancing connection reliability on both sides of a substrate via a through-hole. The circuit board has a substrate with the through-hole, a first conductive part covering an opening of the through-hole on one surface of the substrate in a manner blocking the opening, having a portion inserted into the through-hole from the one surface, and a second conductive part covering a second opening of the through-hole on the other surface of the substrate in a manner blocking the second opening, having a portion inserted into the through-hole from the other surface. The portion of the first conductive part inserted in the through-hole has a columnar shape forming a columnar portion having a diameter smaller than the through-hole. The portion of the second conductive part inserted in the through-hole has a shape that fills a gap between the columnar portion of the first conductive part and an inner surface of the through-hole. Both of the first and the second conductive parts comprise conductive particles being sintered.

A stretchable mounting board that includes a stretchable substrate having a main surface, a stretchable wiring disposed on the main surface of the stretchable substrate, a mounting electrode section electrically connected to the stretchable wiring, solder electrically connected to the mounting electrode section and including bismuth and tin, and an electronic component electrically connected to the mounting electrode section with the solder interposed therebetween. The mounting electrode section has a first electrode layer on a side thereof facing the stretchable wiring and which includes bismuth and tin, and a second electrode layer on a side thereof facing the solder and which includes bismuth and tin. A concentration of the bismuth in the first electrode layer is lower than a concentration of the bismuth in the second electrode layer, and the concentration of the bismuth in the second electrode layer is constant along a thickness direction thereof.

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.