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.

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 a 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.

After there is prepared a conductive paste which contains fine copper particles having an average particle diameter of 1 to 100 nm, each of the fine copper particles being coated with an azole compound, such as benzotriazole, coarse copper particles having an average particle diameter of 0.3 to 20 μm, at least one of a polyvinylpyrrolidone (PVP) resin and a polyvinyl butyral (PVB) resin, a chlorine compound, and a glycol solvent, such as ethylene glycol, the total amount of the fine copper particles and the coarse copper particles being 50 to 90% by weight, and the weight ratio of the fine copper particles to the coarse copper particles being in the range of from 1:9 to 5:5, the conductive paste thus prepared is applied on a substrate by screen printing to be preliminary-fired by vacuum drying, and then, fired with light irradiation by irradiating with light having a wavelength of 200 to 800 nm at a pulse period of 500 to 2000 μs and a pulse voltage of 1600 to 3800 V to form a conductive film on the substrate.

A method includes steps of forming an inner coating on an object and forming an outer coating in contact with the inner coating. A first solution including metal oxide nanoparticles and a first solvent is applied onto the object. The first solvent is removed to form the inner coating with the metal oxide nanoparticles. A second solution having silicon dioxide nanoparticles and a second solvent is applied onto the object. The second solvent is removed to form the outer coating with the silicon dioxide nanoparticles. The interfacial binding force between the metal oxide nanoparticles and the silicon dioxide nanoparticles is then strengthened, for example, by applying a third solution such as water, ethanol or a mixture thereof to the inner coating and the outer coating.

A anisotropic conductive film includes: an electrically insulating adhesive layer; electrically conductive particles disposed in lattice form in the electrically insulating adhesive layer; a reference electrically conductive particle defined, an electrically conductive particle closest to the reference electrically conductive particle defined as a first electrically conductive particle, an electrically conductive particle equally close or next closest to the reference electrically conductive particle regarding the first electrically conductive particle defined as a second electrically conductive particle. The second electrically conductive particle absent from lattice form axis including the reference electrically conductive particle and first electrically conductive particle. A projection image in the anisotropic conductive film longitudinal direction of the reference electrically conductive particle and first electrically conductive particle or second electrically conductive particle overlap and the anisotropic conductive film projection image in a short-side direction the reference electrically conductive particle and second electrically conductive particle or first electrically conductive particle overlap.

A substrate for a printed circuit board according to an embodiment of the present invention includes a base film having an insulating property, and a metal layer formed on at least one surface side of the base film. In the substrate for a printed circuit board, a plurality of fine particles are disposed between the base film and the metal layer, and the fine particles are formed of a metal the same as a main metal of the metal layer or formed of a metal compound of the main metal. The fine particles preferably have an average particle size of 0.1 nm or more and 20 nm or less. The fine particles are preferably formed of a metal oxide or a metal hydroxide. The fine particles are preferably present between the base film and the metal layer so as to form a layer. The metal layer preferably includes a metal grain layer formed by firing metal nanoparticles.

Provided is a silver powder which has an appropriate viscosity range at the time of paste production, can be easily kneaded, and prevents the occurrence of flakes. The silver powder to be used has a specific surface area ratio SA.sub.B/SA.sub.S of 0.5 to 0.9, wherein SA.sub.B is a specific surface area measured by the BET method, and SA.sub.S is a specific surface area calculated from a mean primary-particle diameter D.sub.S measured with a scanning electron microscope. Furthermore, the silver powder preferably has a degree of aggregation of 1.5 to 5.0, the degree being obtained in such a manner that a volume median diameter D.sub.50 measured by laser diffraction scattering is divided by the foregoing Ds.

A wiring substrate includes a first conductor pattern, a second conductor pattern, an insulating layer interposed between the first and second patterns and having a through hole, and a plating conductor integrally formed with the second pattern and filling the through hole in the insulating layer such that the plating conductor is in contact with the first pattern. The through hole has an expansion part such that an opening width of the through hole on the first pattern side is widened, and the plating conductor includes a first plating film directly formed on inner wall of the through hole and a second plating film formed on the first plating film such that the minimum thickness of the first plating film in the expansion part is in the range of 55% to 95% of the minimum thickness of the first plating film in the through hole other than the expansion part.

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.

Provided is a thermosetting resin composition that contains 40 to 80 parts by volume of an inorganic filler with respect to 100 parts by volume of thermosetting resin solids and the inorganic filler. The inorganic filler contains (A) at least one type of particles selected from among gibbsite-type aluminum hydroxide particles and magnesium hydroxide particles having an average particle size (D.sub.50) of 1 to 15 μm; (B) aluminum oxide particles having an average particle size (D.sub.50) of 1.5 μm or less; and (C) a molybdenum compound, and the blending ratios (by volume) of the component (A), the component (B) and the component (C) with respect to 100% as the total amount of inorganic filler are component (A): 30 to 70%, component (B): 1 to 40%, and component (C): 1 to 10%.