Because printed circuit boards are not general terminal products, the definition of names is somewhat confusing. For example, the motherboards used in personal computers are called motherboards, which can not be directly referred to as circuit boards. Although there are circuit boards in the motherboard, they are different. another example is: because there are integrated circuit parts loaded on the circuit board, so the news media called him IC board, but in essence, he is not equivalent to printed circuit boards.
Under the premise that electronic products tend to be multi-functional and complex, the contact distance of integrated circuit components will be reduced, and the speed of signal transmission will be relatively increased, followed by the increase in the number of wiring, the length of wiring between points will be locally shortened, which requires the application of high-density HDI circuit board configuration and micro hole technology to achieve the goal. Wiring and bridging are basically difficult to achieve for single and double-sided boards, so the boards will move towards multi-layer pcb, and because of the continuous increase of signal lines, more power layers and ground layers are the necessary means for design, which makes the multi layer printed circuit board more common.
For the electrical requirements of high speed signals, circuit boards must provide impedance control, high frequency transmission capability, and reduce unnecessary radiation (EMI) with AC characteristics. the use of Stripline and Microstrip structure becomes a necessary design. in order to reduce the quality of signal transmission, insulation materials with low dielectric coefficient and low attenuation rate will be used. In order to match the miniaturization and array of electronic components, PCB will also increase the density to meet the demand. With the appearance of BGA (ball grid array), CSP (chip scale package), DCA (direct chip attachment) and other assembly methods, the printed circuit board is pushed to an unprecedented high-density state.
The hole whose diameter is less than 150um is called Microvia in the industry. The circuit made of the geometry technology of the micropore can improve the efficiency of assembly, space utilization and so on, and it is also necessary for the miniaturization of electronic products.
For this type of printed circuit board products, there have been many different names in the industry to address such boards. for example, the European and American industry used to use the sequential construction method because of the production procedure, so the product was called SBU (Sequence Build Up Process), generally translated as "sequential adding layer method". as for Japanese operators, the pore structure of such products is much smaller than that of the previous ones. Therefore, the manufacturing technology of these products is MVP (Micro Via Process), generally translated as "microporous process". some people also call this kind of circuit board BUM (Build Up Multilayer Board) because the traditional multi-layer board is called MLB (Multilayer Board).
In order to avoid confusion, the IPC Board Association of the United States proposed to call this kind of product the common name of HDI (high density interconnection technology). If translated directly, it will become high-density interconnection technology. but this can not reflect the characteristics of circuit boards, so most circuit board operators call these products HDI board or the Chinese name "high-density interconnection technology". but because of the smoothness of spoken language, some people call this product "high-density PCB" or HDI board.