The rapid development of electronic technology has also made electronic products continue to move towards miniaturization, high performance and multi-function. As a key component of electronic equipment, the performance and design of circuit boards directly affect the quality and functionality of the entire product. Traditional through-hole circuit boards are gradually facing challenges in meeting the complex needs of modern electronic equipment, so the multi-layer structure design of HDI blind and buried via circuit boards emerged as the times require, bringing new solutions to electronic circuit design. With its unique design of blind holes and buried holes, it is essentially different from traditional through-hole boards. It shows significant advantages in many aspects and has a profound impact on the development of the electronics industry.
一、Comparison between the multi-layer structure design of HDI blind and buried via circuit boards and through-hole boards
（一）Characteristics of through-hole board structure
Traditional through-hole circuit boards have through-holes drilled throughout the thickness of the board to achieve electrical connections between different layers. This design is simple and direct, and the processing technology is relatively mature. However, the presence of through-holes occupies a large space and limits the wiring density. When a higher degree of integration is required, the size and number of through-holes will significantly hinder the wiring, and in high-frequency signal transmission, through-holes may introduce additional signal reflections, crosstalk and other problems, affecting signal integrity.
（二）HDI blind and buried via circuit board multi-layer structure design
HDI blind and buried via circuit boards use a more sophisticated design. Blind vias are holes that connect from the outer surface to a specific inner layer, and they do not run through the entire circuit board. Buried vias are holes that connect inner layers and do not extend to the surface of the circuit board. This multi-layer structure design can achieve more complex wiring methods by rationally planning the positions of blind and buried vias. In a multi-layer board, different layers can be connected in a targeted manner through blind and buried vias, so that signals can be efficiently transmitted along the path expected by the designer. For example, for a four-layer HDI blind and buried via circuit board, the first and second layers can be connected through blind vias, the second and third layers can be connected through buried vias, and so on, which greatly improves the flexibility of wiring.
二、Advantages of HDI blind and buried via circuit board multi-layer structure design
(一、) Higher wiring density Since blind and buried vias do not need to occupy a large amount of space like through-holes, HDI blind and buried via circuit boards can achieve more wiring in the same area. This is very important for the continuous miniaturization and functional complexity of modern electronic products. For example, in small mobile devices such as smartphones and tablets, a large number of electronic components and circuits need to be integrated in a limited space. The high wiring density advantage of HDI blind and buried via circuit boards can be fully reflected, which helps to achieve a more compact circuit design.
(二、) Better signal integrity In terms of high-frequency signal transmission, HDI blind and buried via circuit boards perform well. The design of blind and buried vias reduces reflections and crosstalk during signal transmission. Compared with through-hole boards, signals can switch more smoothly between different layers in HDI blind and buried via circuit boards, avoiding signal delays and distortion caused by the long metal column effect of through-holes. This can ensure accurate and fast data transmission and improve the performance of the entire system for application scenarios such as 5G communication modules and high-speed processors that have extremely high requirements for signal quality.
(三、) Improve electrical performance The multi-layer structure of HDI blind and buried via circuit boards can better control the impedance of the circuit. By accurately designing the parameters of blind and buried vias and the dielectric thickness between layers, the impedance of a specific circuit can be optimized. For some circuits that have strict impedance matching requirements, such as radio frequency circuits, this can effectively reduce signal reflections, improve power transmission efficiency, and reduce electromagnetic interference, thereby improving the electrical performance of the entire circuit.
四、Enhanced design flexibility Designers can flexibly design the location and number of blind and buried vias based on specific circuit functional requirements. This flexibility is not only reflected in wiring, but can also be used to optimize power distribution networks, ground plane layout, etc. For example, the power layer and ground layer can be reasonably connected through blind and buried vias to reduce power supply noise, improve power supply stability, and leave more wiring space for other signal lines to meet diverse design requirements.
The multi-layer structure design of the HDI blind and buried via circuit board has a completely different design concept from the through-hole board, showing significant advantages in wiring density, signal integrity, electrical performance and design flexibility, etc., and is a modern The development of the electronics industry provides strong support and promotes electronic products to become smaller, faster, and more stable.