A method for manufacturing a functionally graded composite material for a printed circuit board (PCB) is proposed. The method may include preparing two or more types of mixed powders with different contents of polymer or ceramic powder, each mixed powder comprising (i) a metal powder comprising a powder made of aluminum or an aluminum alloy and a powder of magnesium and (ii) the polymer or ceramic powder. The method may also include laminating the two or more types of mixed powders to form a functionally graded laminate in which a ratio of the content of the polymer or ceramic powder to the content of the metal powder in each of layers stacked in sequence from bottom to the top of the laminate differs. The method may further include preparing a functionally graded composite material by sintering the functionally graded laminate by pressureless sintering or spark plasma sintering.

An interconnect substrate includes a first insulating layer, an interconnect layer formed on a first surface of the first insulating layer, and a second insulating layer formed on the first surface of the first insulating layer to cover the interconnect layer, wherein the second insulating layer includes a first resin layer and a second resin layer, the first resin layer covering at least part of a surface of the interconnect layer exposed outside the first insulating layer, the second resin layer covering the first resin layer, wherein both the first resin layer and the second resin layer contain a resin and a filler, and wherein a proportion of the resin in the first resin layer per unit area is higher than a proportion of the resin in the second resin layer per unit area.

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.

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.

An anisotropic conductive film which suppresses occurrence of short circuit at the time of anisotropic conductive connection, prevents reduction in capturing capability of electrically conductive particles, enables favorable pushing of electrically conductive particles and exhibits not only favorable initial conductivity but also favorable conduction reliability, contains a first electrically conductive particle group and a second electrically conductive particle group, each including a plurality of electrically conductive particles, in an insulating binder. The first electrically conductive particle group and the second electrically conductive particle group are present in a first region and a second region, respectively, which differ from each other in the thickness direction of the anisotropic conductive film and are parallel to the plane direction. Moreover, the first electrically conductive particle group and the second electrically conductive particle group differ from each other in an existence state of the electrically conductive particles.

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.

A wiring substrate for improving connection reliability with an electronic component, a component embedded substrate that incorporates an embedded component into the wiring substrate, and a package structure including an electronic component mounted on the wiring substrate or the component embedded substrate. The wiring substrate includes a metal plate, and a wiring layer including a plurality of insulating layers and a conductive layer arranged on the plurality of insulating layers arranged on at least one principal surface of the metal plate. The plurality of insulating layers includes a first insulating layer to contact the principal surface of the metal plate and has a larger thermal expansion rate in the planar direction than the metal plate and a second insulating layer which is laminated on the first insulating layer to contact the first insulating layer and has smaller thermal expansion rate in the planar direction than the metal plate.

A printed wiring board includes a laminated base material including an insulating layer and a conductor layer formed on the insulating layer, and a solder resist layer laminated on the laminated material and including photosensitive resin. The resist layer has surface portion and portion in contact with the laminated material, the conductor layer has pattern including conductor pads in contact with the resist layer such that the pads are positioned in openings in the resist layer, and the resist layer satisfies a first condition that a chemical species derived from a photopolymerization initiator has concentration higher in the portion in contact with the laminated material than concentration in the surface portion and/or a second condition that the chemical species derived from the initiator in the portion in contact with the laminated material has photopolymerization initiating ability higher than a chemical species derived from a photopolymerization initiator in the surface portion.

A wiring board includes a first electrically-conductive layer; and a first resin layer covering the first electrically-conductive layer, the first resin layer including a resin portion and inorganic insulating particles dispersed in the resin portion. The first resin layer has a first layer region which is in contact with one main surface and side surfaces of the first electrically-conductive layer, and a second layer region which is located on a side of the first layer region which side is opposite to the first electrically-conductive layer. The inorganic insulating particles include a plurality of first inorganic insulating particles contained in the first layer region, and a plurality of second inorganic insulating particles contained in the second layer region. A content rate of the first inorganic insulating particles in the first layer region is lower than a content rate of the second inorganic insulating particles in the second layer region.

A stretchable mounting board that includes a mounting electrode section electrically connected to stretchable wiring, and solder electrically connected to the mounting electrode section. 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.