Patent ID: 8421215

Claim:
A laminated and sintered ceramic circuit board, comprising: a base material comprising a plurality of dielectric layers of a ceramic, a plurality of first surface electrodes, each electrode comprising a conductor exposed at a first principal surface that is one of two principal surfaces of said base material, a plurality of second surface electrodes, each electrode comprising a conductor exposed at a second principal surface that is another of said two principal surfaces, and an inner layer wiring comprising a conductor embedded within said base material; wherein said inner layer wiring electrically connects at least a portion of said first surface electrodes and at least a portion of said second surface electrodes, said inner layer wiring comprises a through conductor extending through at least one of said plurality of dielectric layers in a direction perpendicular to said principal surfaces and inplane conductors extending in a plurality of planes parallel to said principal surfaces, at least a portion of said inplane conductors are fine-lined inplane wiring which has a trapezoidal cross-section perpendicular to the extending direction of said portion, where an upper base and a lower base of said trapezoid are parallel to said principal surfaces, a length (c) of said lower base is 15 μm or less, said portion has an adjacent another portion of said inplane conductors in a plane parallel to said principal surfaces, said adjacent another portion has an another trapezoidal cross-section perpendicular to the extending direction of said adjacent another portion, and an interval (b) between the lower bases of the trapezoids of said portion and said adjacent another portion is 15 μm or less, a height (a) of the trapezoidal cross-section of the inplane conductor constituting said fine-lined inplane wiring and said interval (b) meet the relation represented by the following formula (1): 0.4 ≤ a b , ⁢ a b ≤ 0.6 ( 1 ) said height (a), said interval (b), said length (c) of said lower base and a length (d) of said upper base of the trapezoidal cross-section of inplane conductors constituting said fine-lined inplane wiring meet the relation represented by the following formula (2): - 3 10 × a b + 0.75 ≤ d c , ⁢ d c ≤ - 11 20 × a b + 1.20 . ( 2 )