Thanks to the comprehensive advantages of PCB board and FPC board, soft and hard bonding boards have been widely used in electronic products. In addition, since there are more material differences involved in soft and hard composite plates, all technical challenges mainly come from the selection of material combinations. For example, in the process of multiple laminations, the CTE difference of each layer of material in all directions should be carefully considered and used together with the stiffening plate, so that high-precision alignment lamination can be achieved to achieve deformation compensation.
At the same time, the structure design of the soft and hard composite board is also the hot spot of its development. Generally speaking, there may be many design schemes for soft and hard composite plates with equivalent functions. The actual design shall start from comprehensive consideration, including the reliability, space occupation, weight and assembly complexity of the product. In addition, the manufacturer’s manufacturing capabilities and material elements should be considered for the best design with minimal procurement procedures. For example, common 3-layer to 8-layer soft and hard bonding plates can use CCL copper clad laminate with or without adhesion. Similarly, the covering layer of the flexible area in the soft and hard composite plate has different structures.
Another research and development trend of soft and hard combination board is the manufacturing of component embedded PCB. In most cases, it is required to embed resistors and capacitors in the rigid area without affecting the performance of the flexible area. This application puts forward strict requirements for materials for the second time. In addition, flexible PCB can work normally on CSP chip level packaging technology, while component embedded PCB structure poses challenges and requirements for packaging technology.