Printed circuit boards are the provider of electrical connections for electronic components for more than 100 years. According to the number of circuit boards, printed circuit boards can be divided into single-panel, double-panel, four-layer, six-layer, and other multi-layer boards. To date, printed circuit boards have reached a fairly fine level, and many techniques for improving and optimizing circuit boards have been born. The article mainly outlines the key technologies of printed circuit board manufacturing currently used, including high-density interconnect circuit boards, high-density arbitrary-layer interconnect boards, integrated printed circuit boards, high-heat-dissipation metal substrates, and high-frequency high-speed printed circuits. Key technologies for board and rigid-flex printed board manufacturing.
1. High-density interconnect board
In the early 1990s, Japan and the United States pioneered the application of High Density Interconnect Technology (HDI), which used double-sided or multi-layer boards as core boards, using multiple layers of stacked stacking technology to maintain each level of layout. Absolutely insulated PCB [4-5], manufacturing high-density, highly integrated electronic circuit boards. The five characteristics of this type of circuit board are "micro, thin, high frequency, fine, and heat dissipation." Continuous technological innovation based on five major characteristics is the manufacturing trend of today's high-density electronic circuit boards. "Thin stratification" determines the basis for the survival of high-density electronic circuits. Its birth directly leads to and affects the production of fine, micro-technical. The fine connecting wires, the fine micro-drilling and the insulation design of each layer determine whether the high-density electronic circuit board can adapt to high-frequency operation and whether it is suitable for reasonable heat conduction. This is also an important method to judge the degree of integration of electronic circuits in ultra-high density electronic circuit boards.
2. High-density arbitrary layer interconnect printed circuit board
For different levels of HDI, there are large differences in process manufacturing. In general, the more multi-layered structure, the more complex and precise, the more difficult it is for manufacturing. At present, the association between the layers has several major technological features, namely "step connection", "wrong hole connection", "cross-layer connection" and "stack connection", which will not be described in detail here. Ultra-high-density arbitrary-layer interconnected printed circuit boards are high-end products in printed circuit boards. Its biggest demand comes from the demand for electronic products such as smart phones, notebook computers, digital cameras and LCD TVs that are light, thin and versatile.
3.integrated printed circuit board
Integrated printed circuit board technology integrates one or more separate electronic components (such as resistors, capacitors, capacitors, etc.) into a printed circuit board structure, making the integrated printed circuit board a system function with a certain degree of system function. The printed circuit board has the advantages of improving the reliability of the function of the electronic product system, improving the signal transmission performance, effectively reducing the production cost, making the production process more green and environmentally friendly, and is a technical way for the integration and miniaturization of the electronic device system, and has a huge Market development potential. System integration technology for embedding electronic components in printed boards has already entered the application stage abroad, and has made breakthroughs in related materials and manufacturing process technologies, and foreign-leading companies in the industry have begun to put the technology into mass production.
4.high heat dissipation metal substrate
The high heat dissipation metal substrate mainly utilizes the metal substrate material itself to have better thermal conductivity, and the heat source is derived from the high power component. Its thermal performance is related to the structural layout of the multi-chip (component) package and the reliability of component packaging. High-heat-dissipation metal printed board is used as a high-end printed board. Its metal substrate is compatible with surface mount technology, reduces product size, reduces hardware and assembly costs, replaces fragile ceramic substrates, increases rigidity, and achieves better mechanical durability. Force, showing strong competitiveness in many heat-dissipating substrates, the application prospect is very broad. The buried (embedded) metal-based printed circuit board is a partially implanted metal block printed board, which is a new type of heat-dissipating PCB technology that has appeared in recent years. Its thermal design concept is relatively advanced, and there is no public report on related technologies in domestic and international industry journals. As a heat sink substrate for high-power components, it has the following advantages due to its special design:
(1) Excellent heat dissipation performance, the components are in direct contact with the heat sink block, and there is no heat dissipation bottleneck;
(2) Flexible design method can fully meet the heat dissipation requirements of individual high-power components;
(3) Embedded design, coplanar with PCB, does not affect surface mount (SMD);
(4) Light weight, small size, in line with the mainstream development direction of light, thin, short and small electronic assembly;
(5) Compatible with PCB production processes.
5.high frequency high speed printed circuit board
High-frequency high-speed printed circuits were used in the military field as early as the end of the 20th century. In the past ten years, part of the frequency band of high-frequency communication, which was originally used for military purposes, was given to civilian use, which made the high-speed and high-speed information transmission technology of civilian use leap forward, and promoted the improvement of electronic information technology in various industries. It features long-distance communication, telemedicine surgery, and automated control and management of large logistics warehouses. It should be noted that the electronic components and printed circuit board industries operating in high-frequency signal transmission have strict technical requirements, such as working impedance range, metal wiring smoothness, high-frequency high-speed signal line width requirements, and signal line and The relative distance between the formations, etc. Excellent process technology has driven the industrialization of electronic components and electronic products. It is expected that demand will reach more than 10 times in the next five years.
6.rigid-flex printed board technology
In recent years, the high-performance, multi-functional, and compact and lightweight of electronic devices have shown an accelerated development trend. Therefore, the requirements for miniaturization and high density of electronic components and PCBs used in electronic devices are increasing. In order to meet these requirements, innovations in the fabrication of laminated multi-layer boards for rigid (hard) PCBs have led to the application of various laminated multi-layer boards to electronic equipment. However, mobile devices such as portable devices and digital video cameras have not only accelerated the cycle of adding new functions or performance, but also have a tendency to be smaller, lighter, and more prioritized. Therefore, the space given to the functional parts inside the chassis is only a limited and narrow space, and must be utilized to the maximum extent. In this case, a system structure in which a plurality of small laminated multi-layer boards are combined with a flexible board (FPC) or a cable connecting them is often used, which is called an analog rigid-flex PCB. Rigid-flex PCBs also utilize this combination and are particularly space-saving. They are functional composite multi-layer boards with several rigid PCBs and FPC integration. Rigid-flex PCBs are being widely used in mobile devices because they do not require space for connectors or connections and have almost the same mountability as rigid PCBs.
The above several technologies are currently the most widely used technologies on the market. With the development of electronic technology, more innovative and improved printed circuit board manufacturing technologies will be available in the future.
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