A printed wiring board comprises a sheet-shaped core base material containing a magnetic material, a coil disposed inside the core base material, and an external circuit layer disposed on at least one of first and second surfaces of the core base material opposite to each other.

A conductive adhesive contains a thermosetting resin (A), a conductive filler (B), and a filling-performance improver (C). The thermosetting resin (A) contains a first resin component (A1) having a first functional group, and a second resin component (A2) having a second functional group that reacts with the first functional group. The filling-performance improver (C) contains an organic salt. The conductive adhesive contains from 40 to 140 parts by mass of the filling-performance improver (C) relative to 100 parts by mass of the thermosetting resin.

Implementations of the disclosure are directed to a thermal via filling solder paste that exhibits little to no volume loss during reflow. The solder paste may include a solder powder such as tin-silver-copper alloy, a high melting temperature powder (e.g., a copper powder) having a higher melting temperature than the solder powder, and flux. The high melting temperature powder may be configured to have a melting temperature significantly higher than the solder powder. During reflow, the solder powder may melt and wet to the high melting temperature powder, forming intermetallic compounds that keep the via holes filled during and after reflow soldering.

A circuit board according to the present disclosure includes a substrate, a conductor layer arranged on the substrate, a reflective layer arranged on the conductor layer, and a silicone-resin layer arranged on the substrate. The silicone-resin layer is in contact with the conductor layer and the reflective layer. The silicone-resin layer contains equal to or more than 45% by mass of a plurality of fillers. A first filler whose aspect ratio is larger than 5 occupies equal to or more than 5% of 100% of a total number of the fillers.

A printed wiring board comprises a sheet-shaped core base material containing a magnetic material, a coil disposed inside the core base material, and an external circuit layer disposed on at least one of first and second surfaces of the core base material opposite to each other.

A circuit board structure that includes a resin-based conductive adhesive layer is disclosed, in which a conductive layer is arranged between a first circuit board and a second circuit board. The conductive layer includes a first conductive paste layer and the resin-based conductive adhesive layer is formed on the first conductive paste layer. The resin-based conductive adhesive layer contains a sticky resin material and a plurality of conductive particles distributed in the sticky resin material. The plurality of conductive particles establish an electrical connection between the first conductive paste layer and the resin-based conductive adhesive layer.

An anisotropic conductive film has a three-layer structure in which a first connection layer is sandwiched between a second connection layer and a third connection layer that each are formed mainly of an insulating resin. The first connection layer has a structure in which conductive particles are arranged in a single layer in the plane direction of an insulating resin layer on a side of the second connection layer, and the thickness of the insulating resin layer in central regions between adjacent ones of the conductive particles is smaller than that of the insulating resin layer in regions in proximity to the conductive particles.

A multilayer filter printed circuit board includes filtering material in one or more filter layers. The filtering material can include superconducting material, normal material, magnetic material and semi-conductor material. The multilayer filter printed circuit board may be used as part of a tubular filter structure. The filtering material may be dispersed in, or on the filter layers in a pattern or at random. The filter layers may have a first and second portion that are co-planar, and comprising different filtering materials from one another. The first and second portion may be electrically isolated from one another. Two or more filter layers may comprise different filtering materials from one another. Additional filter layers comprising filtering material may be formed outward of the outer electrically insulative layers.

A method of manufacturing includes bonding a paste material to an organic substrate by a polymer thick film (PTF) process to form a PTF trace, coating a sinterable material over the PTF trace, and sintering the sinterable material to the PTF trace.

A conductive adhesive contains a thermosetting resin (A), a conductive filler (B), and a filling-performance improver (C). The thermosetting resin (A) contains a first resin component (A1) having a first functional group, and a second resin component (A2) having a second functional group that reacts with the first functional group. The filling-performance improver (C) contains an organic salt. The conductive adhesive contains from 40 to 140 parts by mass of the filling-performance improver (C) relative to 100 parts by mass of the thermosetting resin.