SOLDER BALL GRID ARRAY FOR CONNECTING COMPOSITE MILLIMETER WAVE ASSEMBLY

PROBLEM TO BE SOLVED: To provide a ball grid array for forming a reproducibly electric connector with a low loss on a surface of a circuit board. SOLUTION: A coaxially coupled ball grid array 10 is formed in a coaxially coupling part of a plurality of solder balls 16, 20, and 22 formed in a square shape array shape of 3×3. The array comprises the solder ball 16 disposed at a single center for coupling conductors disposed at a center of an axis 26, and a plurality of the solder balls 20, 22 surrounding the ball disposed at the single center in such a manner that some of the plurality of the balls are coupled to a grounded shield of the coaxial line. When they are soldered to each other, the ball disposed at the center and the central conductor of the coaxial line have an appearance of a rod of a diameter having an impedance of standard 5 ohms. The outside conductive shield or the ground signal route of the coaxial line are connected to the plurality of the balls to perform a ground-to- ground connection of lower inductance.