Patent attributes
A wiring board includes a first interconnect layer, a first insulating layer covering the first interconnect layer, a second interconnect layer, thinner than the first interconnect layer, formed on the first insulating layer and having an interconnect density higher than that of the first interconnect layer, and a second insulating layer formed on the first insulating layer and covering the second interconnect layer. The first insulating layer includes a first layer including no reinforcing material, and a second layer including a reinforcing material. The first and second layers include a non-photosensitive thermosetting resin as a main component thereof. The first layer has a coefficient of thermal expansion higher than that of the second layer, and the second insulating layer includes a photosensitive resin as a main component thereof. The second interconnect layer includes an interconnect formed directly on and electrically connected to the first interconnect layer.
