, as a key technological carrier to achieve this goal, has become the core driving force for the development of modern electronics industry with its unique design concept and superior performance, and is widely used in various high-end electronic devices.
1, Core technical characteristics of HDI multilayer circuit board
(1) Ultra high line density and integration
The significant feature of HDI multilayer circuit boards is their ultra-high line density. Compared to traditional multilayer boards, HDI boards can achieve high-density interconnection of more components in limited space by using small apertures (with a minimum aperture of 0.1mm or even smaller), fine lines (with line width/spacing as low as 30 μ m/30 μ m), and blind buried hole technology. For example, in smartphone motherboards, HDI multilayer circuit boards can compactly integrate hundreds of components such as processors, memory, RF chips, etc., greatly reducing the area of the circuit board and providing possibilities for lightweight design of smartphones.
(2) Excellent signal transmission performance
With the continuous improvement of the operating speed of electronic devices, higher requirements have been put forward for the integrity and high speed of signal transmission. HDI multilayer circuit boards can effectively reduce losses and interference during signal transmission by optimizing circuit layout and dielectric materials. The low dielectric constant and low dielectric loss tangent materials used, as well as precise impedance control technology, ensure that high-speed signals (such as millimeter wave signals in 5G communication) remain stable during transmission, avoiding problems such as signal distortion and delay, and ensuring the efficiency of device data processing and transmission.
(3) Flexible interlayer interconnection method
HDI multilayer circuit boards have multiple flexible interlayer interconnection methods, such as blind holes (connecting from the surface to the inner layer, but not penetrating the entire circuit board), buried holes (completely located in the inner layer of the circuit board, not connected to the surface layer), and through holes (penetrating the entire circuit board) combined in design. This diversified interconnection method not only improves the wiring efficiency of the circuit board, but also reduces the parasitic effects of vias on the signal transmission path, enhancing the reliability of signal transmission. At the same time, it also provides greater flexibility for complex circuit design, meeting the efficient connection requirements between different functional modules.
2, Advanced Manufacturing Technology of HDI Multilayer Circuit Board
(1) Layered technology achieves high-density wiring
The core of HDI multilayer circuit board production lies in the layering technology. This technology uses a "layer by layer stacking, gradual layering" approach to construct circuit boards. Firstly, tiny blind holes are fabricated on the core substrate using laser drilling technology, followed by electroplating and hole filling to form interlayer interconnects; Next, the surface is coated with insulating dielectric material and fine circuits are fabricated through processes such as photolithography and etching; Repeat the above steps to gradually increase the number of layers and circuit density of the circuit board. This layering process can accurately control the size of the circuit and the alignment accuracy between layers, achieving high-density and high-precision circuit board production.
(2) High precision laser drilling technology
Laser drilling is one of the key processes in the production of HDI multilayer circuit boards. By using high-energy laser beams, small apertures can be quickly and accurately machined on circuit board materials. Compared with traditional mechanical drilling, laser drilling has the advantages of small aperture, high positioning accuracy, and smooth hole wall, which can meet the strict requirements of HDI board for micro hole processing. Meanwhile, laser drilling can also achieve drilling of any shape, providing more possibilities for complex circuit design.
(3) Advanced electroplating and surface treatment processes
Advanced electroplating and surface treatment processes are essential to ensure the electrical performance and reliability of HDI multilayer circuit boards. In the electroplating process, hole filling electroplating technology is used to ensure that the blind holes and buried holes are filled with copper, improving the conductivity and reliability of interlayer connections; In terms of surface treatment, common processes include chemical nickel deposition and organic solderable protectants, which can effectively protect the surface of circuit boards, improve solderability and oxidation resistance, and extend the service life of circuit boards.
3, Wide application fields of HDI multilayer circuit boards
(1) Smartphones and mobile terminals
As the largest application market for HDI multilayer circuit boards, smartphones have a high demand for the thinning and high-performance of circuit boards. HDI boards have become the preferred choice for smartphone motherboards due to their high integration and excellent signal transmission performance. It can not only integrate key components such as processors, camera modules, and RF modules, but also meet the strict requirements of signal integrity for 5G communication, high-speed data transmission, and other functions, promoting the development of smartphones towards thinner and smarter directions.
(2) Automotive Electronics and Autonomous Driving
Under the trend of intelligent and electrified automobiles, the electronic systems of automobiles are becoming increasingly complex, posing new challenges to the reliability and integration of circuit boards. HDI multilayer circuit boards are widely used in fields such as engine control units, in car infotainment systems, and autonomous driving assistance systems (ADAS) in automobiles. Its high reliability and anti-interference ability can ensure the stable operation of automotive electronic devices in complex electromagnetic environments and harsh working conditions, providing a solid hardware foundation for the development of automotive intelligence.
(3) Communication base stations and 5G equipment
The rapid development of 5G communication technology has put forward higher requirements for the performance and integration of communication equipment. HDI multilayer circuit boards, with their excellent high-speed signal transmission performance and high-density wiring capabilities, have become the core components of communication equipment such as 5G base stations, routers, and switches. It can meet the transmission requirements of millimeter wave signals in 5G communication, support the application of advanced technologies such as large-scale antenna arrays, and help 5G networks achieve high-speed and stable data transmission.
(4) Medical electronic devices
Medical electronic devices such as magnetic resonance imaging equipment, pacemakers, portable medical monitoring instruments, etc. have extremely strict requirements for the accuracy, reliability, and safety of circuit boards. The high precision and high integration characteristics of HDI multilayer circuit boards enable them to meet the demand for miniaturization and intelligence in medical equipment; Meanwhile, its excellent electrical performance and stability ensure the accuracy and reliability of medical equipment during long-term operation, providing strong support for medical diagnosis and treatment.