PCB Technical - What is a high-density printed circuit board (HDI board)

Printed circuit board (HDI board) is a structural element formed by insulating material supplemented by conductor wiring. When the final product is made, integrated circuits, transistors, diodes, passive components (such as resistors, capacitors, connectors, etc.) and various other electronic parts will be installed on it. Through the wire connection, the electronic signal connection can be formed and the application function can be formed. Therefore, the printed circuit board is a platform for providing component connections and a base for receiving connected parts.

Since the printed circuit board is not a general terminal product, the definition of the name is a bit confusing. For example, the motherboard for personal computers is called the motherboard and cannot be directly called the circuit board. Although there are circuit boards in the motherboard, They are not the same, so when evaluating the industry, the two are related but cannot be said to be the same. Another example: because there are integrated circuit parts mounted on the circuit board, the news media call it an IC board, but in fact it is not the same as a printed circuit board.

Under the premise that electronic products tend to be multi-functional and complex, the contact distance of integrated circuit components is reduced, and the speed of signal transmission is relatively increased. This is followed by an increase in the number of wiring and the length of the wiring between points. To shorten the performance, these require the application of high-density circuit configuration and micro-via technology to connect to the target. Wiring and jumper are basically difficult to connect single and double panels, so the circuit board will be multi-layered, and due to the continuous increase of signal lines, more power sources and grounding layers will become necessary means for design All of these have made multi-layer PCBs more common.

For the electrical requirements of high-speed signals, the circuit board must provide impedance control with alternating current characteristics, high-frequency transmission capabilities, and reduce unnecessary radiation (EMI). With the structure of Stripline and Microstrip, multi-layer design becomes a necessary design. In order to reduce the quality problems of signal transmission, insulating materials with low dielectric coefficient and low attenuation rate are used. To cope with the miniaturization and arraying of electronic components, the density of circuit boards is continuously increased to meet demand. The emergence of parts assembly methods such as BGA, CSP, DCA, etc., has pushed the printed circuit board to an unprecedented high-density state.

Holes with a diameter of less than 150um are called micro-holes in the industry. Circuit boards made with this micro-hole geometric structure technology can improve the efficiency of assembly, space utilization, etc., and it is also necessary for the miniaturization of electronic products. sex.

For circuit board products of this type of structure, the industry has had many different names to call such circuit boards. For example, European and American companies once used sequential construction methods for their programs, so this type of product is called SBU (sequence build up process), which is generally translated as "sequence build up process." As for the Japanese industry, because the pore structure produced by this type of product is much smaller than the previous hole, the production technology of this type of product is called MVP (micro via process), which is generally translated as "micro via process." Some people call this type of circuit board BUM (build up multilayer board) because the traditional multilayer board is called MLB (multilayer board), which is generally translated as "build up multilayer board."

Based on the consideration of avoiding confusion, the IPC Circuit Board Association of the United States proposed to call this kind of product the general name of HDI (high density intrerconnection technology), if it is directly translated, it will become a high density connection technology. But this cannot reflect the characteristics of the circuit board, so most of the circuit board industry refers to this type of product as HDI board or the full Chinese name "High Density Interconnection Technology". However, due to the problem of oral compliance, some people directly call such products high-density PCB or HDI boards.