HDI board is a kind of using micro buried blind hole technology, close a circuit board line distribution. Mainly used in high-end products, the emergence of HDI board development, there is light, thin, short, small electronic products. One, the basic concept of HDI board 1, HDI: HighDensityInterconnectionTechnology high-density interconnect technology. Is the micro layer method and blind hole buried the PCB manufacturing laminated. 2, microporous: in PCB, the diameter of less than 6 mil ( 150um） The hole is called the pores. 3, blind hole: BlindVia, connecting surface and inner layer and not through the whole guide hole. 4, buried hole: BuriedViaHole, buried inner hole, see in the finished product, it is mainly used for the inner circuit conduction, can reduce the rate of signal interference, maintain the continuity of transmission line characteristic impedance. Due to the buried hole of PCB surface area, therefore can be placed in the PCB surface more components. HDI board, HDI board structure classification of HDI no fixed process, stack structure and production process with the requirement of drilling. 1, HDI drilling formation can be divided into: laser blind hole, buried drill hole, drill hole. 2, based on HDI process can be divided into a first order process: 1 + N + 1 second order process: 2 + N + 2 third-order process: 3 + N + 3 fourth order process: 4 + 4 N + 3, HDI board 1, which can realize the advantages of higher density of wiring. 2, narrow solder area, decrease of hole to hole distance, reduce the size of the PCB. 3, to reduce the loss of electrical signal. High density integration of HDI technology can be further miniaturization of electronic products, meet the needs of the miniaturization of electronic products. The HDI is widely used in mobile phones, digital cameras and other high-end electronic products.