PRINTED BOARD DEVICE

PURPOSE:To reduce noise generated at the time of inserting/removing a hot line and prevent the malfunction of other printed boards by connecting the ground of the printed board whose hot line is to be inserted/removed with the ground of a back board by using low-impedance conductor. CONSTITUTION:A back board 1 supports printed boards 4 and 10 by means of a signal connector 11, sends and receives a signal between the printed boards and supplies power from a power source device 3. When a hot line is removed from the printed board 4, the printed board 4 is separated from the signal connector 11. At that time, the pin of the printed board 4 repeats disconnection. A ground pin in the signal connector 11 also repeats disconnection at the same time. Therefore, for the ground of the printed board 4, the increase of the potential is observed, however, it sends only the noise whose VT product is small since the conductor 8 possessing the inductance of several 10nH or less at the direct current resistance of 10mOMEGA/cm or less is connected with a ground pad, and the malfunction of other printed boards is prevented.