A flexible circuit board is referred to as a soft board, and is a printed circuit board made of a flexible insulating substrate. Since it has a function that can be freely bent, wound, folded, and the like, a flexible printed circuit board is manufactured. After completion, it is also necessary to press the steel sheet with mechanical protection properties at its specific position to become the final flexible printed circuit board product. However, the existing surface is formed with a metal layer of reinforcing steel sheet and flexible circuit board. After the combination, problems such as bubbles, delamination and falling off are apt to occur between the flexible circuit board and the reinforcing steel sheet.
　　 In order to solve the above problem, in a Chinese patent document with the patent application number "201320313606.1", a flexible circuit board reinforcing steel sheet is described, which comprises a steel sheet and a metal layer on the surface of the steel sheet, wherein the metal layer faces away from The surface of the steel sheet is a concave-convex surface, and the vertical distance between the highest point of the concave-convex surface and the lowest point of the concave-convex surface is smaller than the vertical distance between the highest point of the concave-convex surface and the surface of the metal layer facing the steel sheet, and the concave-convex surface of the metal layer has a certain roughness Under the condition that the surface of the metal layer facing away from the steel sheet is a rough surface, when the uneven surface of the metal layer is bonded to the flexible circuit board by the conductive adhesive, the metal layer and the conductive paste having the uneven surface of the bonding surface can be ensured. The larger the bonding area, so that the peeling force between the reinforcing steel sheet and the flexible circuit board is enhanced, and the flexible circuit board to which the reinforcing steel sheet is attached is prevented from foaming, delaminating and lining in the subsequent operation. The phenomenon of falling off.
　　 However, the above-mentioned steel sheet reinforcing sheet is disadvantageous in that, since the working chip is mounted on the flexible circuit board, the flexible circuit board generates a large amount of heat when working, and the steel sheet reinforcing sheet is attached to the back surface of the flexible circuit board, steel The sheet reinforcing sheet blocks the heat dissipation performance of the back surface of the flexible circuit board, thereby causing the temperature of the entire flexible circuit board to be too high, which affects the service life of the flexible circuit board.
　　 In view of the deficiencies of the prior art, the object of the present invention is to provide a steel sheet reinforcing sheet for a flexible circuit board, which has better heat dissipation performance for the flexible circuit board, thereby ensuring a good service life of the flexible circuit board. .
　　 The above technical object of the present invention is achieved by the following technical solutions: a steel sheet reinforcing sheet for a flexible circuit board, comprising a reinforcing steel sheet for attaching to the back surface of the flexible circuit board, the reinforcing steel sheet is opened There is a heat dissipation passage from the upper surface of the reinforcing steel sheet to the side or bottom surface of the reinforcing steel sheet.
　　 Through the above technical solution, the reinforcing steel sheet is provided with a heat dissipation passage penetrating from the upper surface to the side or the bottom surface of the reinforcing steel sheet, and the reinforcing steel sheet is bonded on the flexible circuit board, and the heat on the back surface of the flexible circuit board enters the heat dissipation. In the channel, finally, it is radiated from the heat dissipation channel. In the present invention, the heat dissipation channel acts as a heat dissipation on the back surface of the flexible circuit board, thereby reducing the temperature of the surface of the flexible circuit board, and ensuring that the flexible circuit board can be normally used in a high temperature environment. , has a good service life.
　　 Preferably, the upper surface of the reinforcing steel sheet is provided with a hemispherical shape bump, and the heat dissipation passage includes an air inlet disposed at the top of the bump.
　　 Through the above technical solution, the upper surface of the reinforcing steel sheet is provided with a hemispherical shape bump, and the heat dissipation passage includes an air inlet disposed at the top of the bump, and the air inlet is disposed at the top of the bump, and the opening of the air inlet is higher than Reinforcing the upper surface of the steel sheet, setting the opening height of the air inlet to be higher than the upper surface of the reinforcing steel sheet, and then coating the conductive rubber on the upper surface of the reinforcing steel sheet, and the height of the coated conductive rubber It is roughly equal to the opening height of the air inlet and the setting of the bumps. It is convenient to avoid the air inlet when coating the conductive glue, so as to prevent the conductive glue from infiltrating into the air inlet, so that the air inlet maintains good patency.