In a terminal plate circuit in which the bottom surface of the diode is attached to the surface of the terminal plate with solder so as to dissipate the heat of the diode, heat transfer from the diode to the terminal plate is facilitated by removing the air bubbles in the solder during the soldering. A terminal plate circuit configured in such a manner that a metal part of a bottom surface of a diode of surface mounting type is soldered onto a surface of a terminal plate that is larger than the metal part, characterized in that streaks consisting of a plurality of lines that do not intersect with each other are formed on the surface of the terminal plate onto which the diode is to be soldered, whereby air bubbles generated within the solder during the soldering are let to escape from a lower surface of the diode to outside through the streaks. This terminal plate circuit is suitable for the use in a terminal box for solar cell panel.