As electronic products have higher and higher requirements for volume, especially the size of mobile device products is continuously shrinking. For example, the current popular Ultra Book products, and even novel wearable smart devices must use HDI circuit board height The carrier board made of density interconnection technology further reduces the product size by terminal design.
HDI circuit board is high-density interconnection technology, which is one of the technologies used in printed circuit boards (Printed circuit board). HDI is mainly produced by using the technology of micro-blind buried holes. Its characteristic is that it can make the electronic circuit distribution circuit density in the printed circuit board higher. However, due to the large increase in circuit density, the printed circuit board made of HDI cannot use ordinary drills. To form holes, HDI must adopt a non-mechanical drilling process. There are quite a lot of non-mechanical drilling methods, among which "laser drilling" is the main hole-forming solution for HDI high-density interconnection technology.
HDI printed circuit boards are widely used in a wide range of applications. Electronic products such as mobile phones, ultra-thin notebook computers, tablet computers, digital cameras, automotive electronics, digital cameras, etc., have used HDI technology to reduce the design of the motherboard. The benefits of HDI are quite large. Not only can the design of the end product leave more space in the mechanism for batteries or more additional functional components, but the cost of the product can also be relatively reduced due to the introduction of HDI.
HDI was used in mid-to-high-priced mobile phones in the early days and is now widely used in almost all mobile devices
The products that used the most HDI technology in the early stage were mainly functional mobile phones and smart phones. These products accounted for more than half of the HDI high-density circuit boards, while Any-layer HDI (any layer high-density connection board) was high-end. The biggest difference between the HDI production process and the general HDI circuit board is that most HDIs are machine drilled through the drilling process for PCB penetration processing. As for the board between layers, Any-layerHDI uses "laser" drilling to get through each The interconnected design of the first floor.
For example, using the Any-layerHDI manufacturing method can generally reduce the PCB volume by about 40%. Currently, Any-layer HDIE is used for Apple iPhone4 or newer smart phones, and reduces product design by integrating higher-density motherboards. Thickness enables product design to be marketed in a lighter and thinner design. However, Any-layer HDI is manufactured by laser blind vias, which is relatively more difficult in circuit processing and production, and the cost is higher than that of ordinary circuit boards. At present, only mobile devices with high unit prices are used more.
HDI printed circuit boards are manufactured using the build-up method. The technical gap of HDI lies in the number of build-up layers. The more circuit layers, the higher the technical difficulty! The general-purpose HDI board can basically be used once Build-up, as for high-end HDI boards, it is manufactured with two or more build-up build-up technologies. In order to avoid damage to the high-density wiring of HDI boards caused by mechanical perforation due to improper drilling, the hole forming process can be At the same time, advanced printed circuit board manufacturing technologies such as laser perforation, electroplating filling, and stacking are used.
High pin count critical components require HDI for product design
Especially FPGA components with a large number of pins are a great problem for PCB layout. For example, the most common GPU components are also developing towards more and more pins, and most of them have switched to HDI printed circuit boards. For product design, HDI boards are especially suitable for design solutions that require highly complex connections.
Especially for the new generation of SoC or integrated chip, its highly integrated function leads to more and more IC pins, which greatly increases the difficulty of PCB design connection lines, and the HDI high-density circuit board design scheme can use the internal multi-layer The advantages of interconnection and integration complete the connection of complex chip pins one by one, and laser blind hole manufacturing can make micro blind holes in the board, which can be perforated, offset, stacked, or in any layer For interconnection, the layout flexibility of the circuit is relatively higher than that of the traditional PCB, and it also provides an easier board design solution for high-pin-count integrated chip applications.
The HDI circuit board design is also more complicated than the previous PCB circuit boards. Not only the lines become tighter, but also the design complexity of using different layers of circuit interconnection is also greatly increased, and the lines become thinner and tighter. It means that the cross-sectional area of the conductor of the line changes smaller, which will lead to more prominent problems in the integrity of the transmitted signal. For PCB design engineers, it is necessary to spend more attention on board function verification and error checking.
Especially in the face of highly complex design cases, for example, the electronic circuit of the board is very likely to encounter design changes during the development process, and if the core components of the motherboard have FPGA or other components with a large number of pins, a slight design change will It will cause delays in the design improvement schedule, and how to minimize the occurrence of circuit deployment errors in the frequently changing design process must be equipped with design aids that can support HDI high-complexity circuit design, especially in FPGA logic. Design, hardware design, PCB logic and related design data can communicate with each other under the design framework, so that any project design specification changes can be reflected in the development system in real time, avoiding design problems that the design board and the target chip cannot match.
HDI requires high line density and needs to use laser to open holes
In fact, there is no clear definition of the HDI high-density manufacturing method, but generally there is a considerable difference between HDI and non-HDI. First, the aperture used for the circuit substrate made of HDI must be less than or equal to 6mil (1/1,000), As for the ring diameter of the annular ring, it needs to be 10mil, and the layout density of the line contacts needs to be greater than 130 points per square inch, and the line spacing of the signal lines needs to be less than 3mil.
The advantages of HDI printed circuit boards are quite a lot. Due to the highly integrated circuit of HDI, the area of the used board can be greatly reduced, and the higher the number of layers, the board area that can be reduced can also be increased accordingly. Due to the smaller size of the substrate, the application of HDI The area of the circuit board can be 2~3 times smaller than that of non-HDI circuit board design, but it can maintain the same complex circuit. Naturally, the material weight of the board can be reduced by this. As for the design of specific block circuits such as radio frequency and high frequency, multi-layer
