High-density interconnection board (HDI) is a high-density interconnection board, which is a circuit board with high linear density distribution using micro-blind buried vias. The HDI board has inner layer lines and outer layer lines, and then connects the inside of each layer using processes such as drilling and metallization in the holes. The HDI board is a high-density interconnection circuit board, and the blind hole board and auxiliary press board are HDI boards, which are divided into first order, second order, third order, fourth order, fifth order, HDI, etc. For example, the iPhone 6 motherboard is fifth-order.
HDI boards are usually manufactured by a lamination method. The more layers are stacked, the higher the technical level of the board. Ordinary HDI boards are basically disposable laminates. High-end HDI adopts two-layer or multi-layer technology and adopts advanced PCB technology, such as stacking holes, electroplating holes and laser direct drilling. When the density of the PCB exceeds eight layers, it is manufactured with HDI, and the cost will be lower than the traditional complex pressing process. HDI board helps to use advanced packaging technology, its electrical performance and signal accuracy are higher than traditional PCB. In addition, HDI boards have better improvements in radio frequency interference, electromagnetic interference, electrostatic discharge, heat conduction, etc.
Electronic products continue to develop high-density and high-density precision. The so-called "high", in addition to improving the performance of the machine, also reduces the size of the machine. High-density integration (HDI) technology makes the end product design more compact, while meeting higher standards of electronic performance and efficiency.
HDI is widely used in mobile phones, digital cameras, MP3, MP4, notebook computers, automotive electronics and other digital products, among which mobile phones are the most widely used. HDI board is generally manufactured by build-up method. The more the number of layers, the higher the technical level of the board. The common HDI board is basically one time stacking, and the high-level HDI adopts two or more times stacking technology, and at the same time, advanced PCB technologies such as stacking holes, electroplating filling holes, laser direct drilling are used. High level HDI board is mainly used in 3G mobile phones, advanced digital cameras, IC carrier boards, etc. But, how to distinguish the first order, second order and third order of HDI PCB?
The first order is relatively simple, and the process and the process are well controlled.
The second order started to be very troublesome, one was alignment issues, and one was punching and copper plating issues. There are various second-order designs. One is the staggered position of each step. When connecting sub-adjacent layers, wires are connected in the middle layer. This is equivalent to two first-order HDI.
The second is the overlap of two first-order holes, and the second order is achieved by superposition. The processing is similar to two first-order, but there are many technical points that require special control, namely the above. The third type is perforation directly from the outer layer to the third layer (or N-2 layer). This process is very different from the previous one, and stamping is more difficult.
For the third order is by analogy to the second order.
HDI circuit can reduce the cost of PCB when the density of PCB increases more than eight layers, the cost of manufacturing with HDI will be lower than that of traditional complex pressing process. It can also increase circuit density that interconnection between traditional circuit board and parts. It is conducive to the use of advanced structural technology and provide better electrical performance, signal correctness and better reliability. HDI improves thermal properties and RFI / EMI / ESD, increasing design efficiency.
Common PCB board is mainly FR-4, made of epoxy resin and electronic grade glass cloth. Generally speaking, the traditional outer layer of HDI uses bonded copper foil. Because laser drilling cannot open the glass cloth, generally bonded copper foil without glass fiber is used. Through 1180 glass cloth，this is no different from ordinary materials.