Abstract: A multilayer wiring substrate includes a first wiring substrate including a plurality of stacked layers made of a thermosetting resin and having a wiring layer formed between each adjacent layers of the layers in a state in contact with the adjacent layers; a second wiring substrate made of a ceramic; and a joining layer disposed between a back surface of the first wiring substrate and a front surface of the second wiring substrate and configured to join the first wiring substrate and the second wiring substrate to each other. At least a surface of the joining layer adjacent to the second wiring substrate is made of a thermoplastic resin.

Abstract: Embodiments of the present invention provide a component-built-in wiring board capable of preventing a defect, such as a crack, resulting from stress concentration at a corner, when a component is accommodated in a housing portion of a core material with resin filler filled therebetween. The component-built-in wiring board can include a component accommodated in the housing portion of a core material, and a laminate portion in which insulating layers and conductor layers are laminated alternately on the core material. A gap between the housing portion of the core material and the component can be filled with a resin filler. In an inner circumferential portion of the housing portion of the core material a first straight chamfered portion is formed at each corner of a rectangle, and in an outer circumferential portion of the component a second straight chamfered portion is formed at each corner of a rectangle.

Abstract: Embodiments of the present invention provide a component-built-in wiring board capable of preventing a defect, such as a crack, resulting from stress concentration at a corner, when a component is accommodated in a housing portion of a core material with resin filler filled therebetween. The component-built-in wiring board can include a component accommodated in the housing portion of a core material, and a laminate portion in which insulating layers and conductor layers are laminated alternately on the core material. A gap between the housing portion of the core material and the component can be filled with a resin filler. In an inner circumferential portion of the housing portion of the core material a first straight chamfered portion is formed at each corner of a rectangle, and in an outer circumferential portion of the component a second straight chamfered portion is formed at each corner of a rectangle.