Currently, PCB products are transitioning from traditional to higher-density HDI/BUM boards, IC packaging base (carrier) boards, embedded component boards, and rigid-flex boards. PCBs are approaching the limit of “printed circuit boards”, and will eventually shift from “electrical transmission signal” to “optical transmission signal”, replacing printed circuit boards with printed optical circuit boards. The rapid development of electronic products demands a move towards products characterized by high density and refinement. PCB products have partially or fully transitioned to high-density interconnect laminate (HDI/BUM) boards, package base (carrier) boards, integrated (embedded) component printed boards (ICCB) and rigid-flex printed boards (G-FPCB). In the future, advanced printed optical circuit boards will replace the current electrical signal transmission and computing. The output value of HDI/BUM boards with core boards accounts for 95%. HDI/BUM boards are denser than conventional printed boards, and can be categorized as HDI/BUM boards with core boards and without core boards. The increase in density is significant for the HDI/BUM boards with core boards, making them suitable for high-density installations. IC packaging substrates are developed on the basis of HDI/BUM boards and are essential for solving the CTE matching problem. These substrates provide interconnection and mechanical support for components, and are required to have lower CTE to ensure reliability. The CTE compatibility between the package substrate and the packaged components must be addressed, as mismatch can threaten the reliability and life of electronic products. IC packaging substrates must be denser, thinner, and smaller, and use low-CTE materials to meet these demands.