The difference between HDI board and normal PCB
HDI board（High Density Interconnector）, a high-density interconnect board, is a circuit board with a relatively high density of line distribution using micro-bumping. The HDI board has an inner layer line and an outer layer line, and then uses a process such as drilling and metallization in the hole to connect the inside of each layer.
HDI boards are generally manufactured by a laminate 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.
When the density of the PCB increases beyond the eight-layer board, it is manufactured in HDI, and the cost will be lower than that of the conventional complicated pressing process. The HDI board facilitates the use of advanced packaging technology, and its electrical performance and signal correctness are higher than traditional PCB. In addition, HDI boards offer better improvements in RF interference, electromagnetic interference, electrostatic discharge, heat transfer, and more.
Electronic products continue to develop toward high density and high precision. The so-called "high", in addition to improving machine performance, also reduces the size of the machine. High-density integration (HDI) technology enables end-product design to be more compact while meeting higher standards of electronic performance and efficiency. Currently popular electronic products, such as mobile phones, digital (camera) cameras, notebook computers, automotive electronics, etc., are mostly using HDI boards. With the upgrading of electronic products and the needs of the market, the development of HDI boards will be very rapid.
Normal PCB introduction
PCB (Printed Circuit Board), the Chinese name for printed circuit boards, also known as printed circuit boards, is an important electronic component, a support for electronic components, and a carrier for electrical connection of electronic components. Because it is made by electronic printing, it is called a "printing" circuit board.
Its main function is that after the electronic equipment adopts the printed board, due to the consistency of the same printed board, the manual wiring is avoided, and the electronic components can be automatically inserted or mounted, automatically soldered, and automatically detected. The quality of electronic equipment increases labor productivity, reduces costs, and facilitates maintenance.
HDI board is high-density interconnect circuit board, blind hole plating and secondary pressing board are HDI boards, which are divided into first-order, second-order, third-order, fourth-order, fifth-order and other HDI. For example, the motherboard of iPhone 6 is fifth-order. HDI.
A simple buried hole is not necessarily HDI.
How to distinguish between first-order and second-order and third-order of HDI PCB
The first order is relatively simple, and the process and process are well controlled.
The second order began to be troublesome, one is the alignment problem, one punching and copper plating problem. There are a variety of second-order designs. One is the staggered position of each step. When connecting the sub-adjacent layers, the wires are connected in the middle layer. This is equivalent to two first-order HDI.
The second is that the two first-order holes overlap, and the second-order is realized by superposition. The processing is similar to the two first-order, but there are many technical points to be specially controlled, that is, the above.
The third type is to directly punch from the outer layer to the third layer (or the N-2 layer). The process is much different from the front, and the punching is more difficult.
For the third order, the second-order analogy is.
Ordinary PCB boards are mainly FR-4, which is made of epoxy resin and electronic grade glass cloth. Generally, the traditional HDI, the outermost use of adhesive copper foil, because of laser drilling, can not open the glass cloth, so generally use glass fiber-free adhesive copper foil, but now high-energy laser drill can already penetrate 1180 glass cloth . This is no different from ordinary materials.