How to understand the difference between an HDI PCB board and a regular PCB board

How to understand the difference between an HDI PCB board and a regular PCB board

Introduction to HDI board

HDI board (High Density Interconnector), also known as high-density interconnect board, is a circuit board that uses micro blind buried hole technology and has a relatively high line distribution density. The HDI board has both inner and outer circuits, which are connected internally by drilling and metallization processes.

HDI boards are generally manufactured using the stacking method, and the more times they are stacked, the higher the technical level of the board. Ordinary HDI boards are basically stacked once, while higher-order HDI uses two or more layers of technology, as well as advanced PCB technologies such as hole stacking, electroplating filling, and laser direct drilling.

When the density of a PCB increases by more than eight layers, manufacturing with HDI will result in lower costs compared to traditional complex lamination processes. HDI boards are conducive to the use of advanced assembly technology, and their electrical performance and signal accuracy are higher than traditional PCBs. In addition, HDI boards have better improvements in radio frequency interference, electromagnetic wave interference, electrostatic discharge, heat conduction, etc.

Electronic products are constantly developing towards high density and precision. The so-called "high" not only improves machine performance, but also reduces the size of the machine. High density integration (HDI) technology can make terminal product design more miniaturized, while meeting higher standards of electronic performance and efficiency. Currently, many popular electronic products, such as mobile phones, digital cameras, laptops, automotive electronics, etc., use HDI boards. With the upgrading of electronic products and market demand, the development of HDI boards will be very rapid.

Introduction to Ordinary PCB

PCB (printed circuit board), also known as printed circuit board in Chinese, is an important electronic component that supports electronic components and serves as the carrier for electrical connections of electronic components. Due to its use of electronic printing technology, it is called a "printed" circuit board.

Its main function is to avoid manual wiring errors due to the consistency of similar printed boards in electronic equipment, and to achieve automatic insertion or installation of electronic components, automatic soldering, and automatic detection, ensuring the quality of electronic equipment, improving labor productivity, reducing costs, and facilitating maintenance.

Are PCB boards with blind buried holes called HDI boards?

HDI boards refer to high-density interconnect circuit boards. The boards with blind hole electroplating and secondary pressing are all HDI boards, which are divided into first, second, third, fourth, and fifth order HDIs. For example, the motherboard of the iPhone 6 is a fifth order HDI.

Simply burying holes does not necessarily mean HDI.

How to distinguish between first order, second order, and third order HDI PCB

The first level is relatively simple, and the process and process are easy to control.

The second order problem starts to get troublesome, one is the alignment problem, and the other is the punching and copper plating problem. There are various second-order designs, one of which is to stagger the positions of each stage and connect the secondary layers through wires in the middle layer, which is equivalent to two first-order HDIs.

The second method is to overlap two first order holes and achieve second order through superposition. The processing is also similar to two first order holes, but there are many process points that need to be specially controlled, which is mentioned above.

The third method is to directly drill holes from the outer layer to the third layer (or N-2 layer), with many different processes and greater difficulty in drilling

For the third order, the second order analogy is.

The difference between HDI board and ordinary PCB

The ordinary PCB board is mainly FR-4, which is made by pressing epoxy resin and electronic grade glass cloth. Generally, traditional HDI requires the use of adhesive backed copper foil on the outside. Due to laser drilling, it is not possible to penetrate glass cloth, so it is generally necessary to use adhesive backed copper foil without glass fiber. However, current high-energy laser drilling machines can already penetrate 1180 glass cloth. This makes no difference from ordinary materials.