Electronic design is also trying to reduce its size while continuously improving the performance of the whole machine. From mobile phones to smart small portable products, small is always the same pursuit. High-density integration (HDI) technology enables end-product design to be more compact while meeting higher standards of electronic performance and efficiency. HDI is currently widely used in mobile phones, digital (camera) cameras, MP3, MP4, notebook computers, automotive electronics and other digital products, among which mobile phones are the most widely used. HDI boards are generally manufactured using a build-up method. The more times the layers are stacked, the higher the technical grade of the board. Ordinary HDI boards are basically one-time laminate, high-order HDI uses two or more layers of technology, and adopts advanced PCB technology such as stacking holes, plating holes, and laser direct drilling. High-end HDI boards are mainly used in 3G mobile phones, advanced digital video cameras, IC carrier boards, etc.