| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an electronic component mounting substrate by which the whole device can be prevented from being larger and wiring efficiency can be improved. SOLUTION: A first pad group is formed on the outermost layer of a build-up layer B3 constituted by laminating interlayer insulating layers 8a, 8b and inner layer conductor layers 9a alternately. The interlayer insulating layers 8a, 8b of the build-up layer B3 are composed of a photosensitive resin hardly soluble with acid or an oxidizing agent and heat resistant resin particles soluble with acid or an oxidizing agent. The inner layer conductor layers 9a connecting pads 12 of the first pad group and pads 14 of a second pad group are connected by via holes 11 formed in the interlayer insulating layers 8a, 8b. There are connections by via holes centrifugally arranged towards the outer periphery of the substrate in a forward direction at all times and connections by via holes 11 formed in the interlayer insulating layer 8a, 8b arranged in series.</p> |
