Importance

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Abstract

To provide a wiring substrate which can reliably prevent progress of cracking in a solder bump, and which exhibits improved reliability. The wiring substrate 10 of the present invention includes a substrate main body 11, pads 61, and a solder resist 81. The pads 61 are provided on the substrate back surface 13 of the substrate main body, and have surfaces 62 on which solder bumps 84 employed for connection of a motherboard 91 can be formed. The solder resist 81 covers the substrate back surface 13 of the substrate main body, and has openings 82 through which the pads 61 are exposed. A protrusion 71 is formed on a portion of the surface 62 of each pad 61. The height A4 of the end surface 72 of the protrusion 71, as measured from the surface 62 of the pad 61, is smaller than the depth of each opening 82. The protrusion 71 is provided in the opening 82 such that the peripheral surface 73 of the protrusion 71 faces the inner surface of the opening 82, and the protrusion 71 has a plan-view shape similar to that of the opening 82.

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First Claim