| 摘要 |
PROBLEM TO BE SOLVED: To make a structure approximate to a coaxial pin structure, enable control of impedance and reduce noise at the time of high speed signal propagation, by arranging a printed board for noise reduction which has through holes into which pins are inserted and a ground layer, between a printed board and a pin grid array. SOLUTION: A GND layer 4 in a PGA board 1 is connected with a GND layer 4 in a printed board 2 by using pins, and, at the same time, connected with a GND layer 4 in a board 3 for noise reduction by through hole plating for GND pins of the board 3 for noise reduction. FR4, polyimide, etc., may be used for material of the board 3 for noise reduction, and the thickness of the board 3 is slightly smaller than the length of the pins 7 of the PGA board 1. Since the board 3 for noise reduction is in contact with the GND pins, an inner layer is grounded. The inner layer keeps a clearance of a constant gap around a signal pin, and has a structure approximate to a coaxial pin. Thereby discontinuity in impedance is excluded at the parts of the pins 7, and generation of noise can be restrained.
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