Multi-layer flexible circuit board and preparation method thereof

The invention provides a multi-layer flexible circuit board comprising a flexible substrate, a first metal layer, and a second metal layer. The first metal layer and the second metal layer are arranged successively on the back of the flexible substrate. At least three conducting layers are arranged on the front side of the flexible substrate. A through hole is formed in the flexible substrate and is formed by carrying out punching on the substrate along a substrate back thickness direction. The conducting layer at the upper layer is connected with the conducting layer at the lower layer by a hot melt adhesive layer coated on the surface of the conducting layer at the upper layer; the conducting layer at the bottom is connected with the flexible substrate by a hot melt adhesive layer coated on the surface of the conducting layer at the bottom. A circuit diagram layer is printed on the conducting layers except the conducting layer on the top. 本发明提供种多层柔性线路板，该多层柔性线路板包括柔性基板以及位于柔性基板背面依次设置的第金属层和第二金属层；在柔性基板的正面设置有至少三层