If the circuit design is relatively simple, the total volume is small, and the space is suitable, the traditional internal connection mode is much cheaper. If the circuit is complex, processes many signals or has special electrical or mechanical performance requirements, flexible circuit is a good design choice. When the size and performance of applications exceed the capacity of rigid circuits, flexible assembly is the most economical. A 12mil pad with 5mil through-hole inside and a flexible circuit with 3mil lines and spacing can be made on one film. Therefore, it is more reliable to mount the chip directly on the film. Because there is no flame retardant that may be the source of ion drilling pollution. These films may be protective and cured at higher temperatures to obtain higher glass transition temperatures. The reason why flexible materials save cost compared with rigid materials is that connectors are not required. (Editor：admin)