Ultra-precision PCB Fabrication, High Frequency PCB, High Speed PCB, IC Substrate, Multilayer PCB and PCB Assembly.
The most reliable PCB custom service factory.
PCB Tech

PCB Tech

PCB Tech

PCB Tech

HDI board
2021-08-30
View:41
Author:Belle

HDI board is the abbreviation of High Density Inverter. It is a kind of (technology) for the production of printed boards. It is a circuit board with a relatively high line distribution density using micro-blind and buried via technology. HDI board is a compact product designed for small-capacity users. It adopts a modular design that can be connected in parallel. One module has a capacity of 1000VA (1U height) and is naturally cooled. It can be directly placed in a 19" rack, and a maximum of 6 modules can be connected in parallel. The product adopts all-digital signal process control (DSP) technology and multiple This patented technology has a full range of adaptable load capacity and strong short-term overload capacity, regardless of load power factor and crest factor.


In fact, the HDI high-density manufacturing method does not have a clear definition, but the difference between HDI and non-HDI is generally quite large. First of all, the diameter of the circuit carrier board made of HDI must be less than or equal to 6mil (1/1,000 inch). As for the ring diameter of the hole ring, it needs to be ≦10mil, and the layout density of the line contact needs to be greater than 130 points per square inch, and the line spacing of the signal line needs to be 3mil or less.



HDI board manufacturing is the fastest growing field in the printed circuit board industry. From the first 32-bit computer launched by Hewlett-Packard in 1985, to today's large client server with 36 sequential laminated multilayer printed boards and stacked micro-vias, HDI/micro-via technology is undoubtedly the future PCB architecture. Larger ASICs and FPGAs with smaller device pitches, more I/O pins and more embedded passive devices have shorter and shorter rise times and higher frequencies. They all require smaller PCB feature sizes, which promotes the Strong demand for HDI/micro vias.


HDI boards are mainly made using the technology of micro-blind buried vias. The characteristic is that the electronic circuits in the printed circuit board can be distributed with higher circuit density, and due to the large increase in circuit density, the printed circuit board made of HDI board cannot be used. Generally, for drilling holes, HDI must adopt a non-mechanical drilling process. There are many non-mechanical drilling methods. Among them, "laser drilling" is the main hole-forming solution of HDI high-density interconnection technology.


HDI board

First-order process: 1+N+1

Second-order process: 2+N+2

Third-order process: 3+N+3

Fourth-order process: 4+N+4


Under the premise that electronic products tend to be multi-functional and complex, the contact distance of integrated circuit components is reduced, and the speed of signal transmission is relatively increased. This is followed by an increase in the number of wiring and the length of the wiring between points. The performance is shortened, these require the application of high-density pcb circuit configuration and microvia technology to achieve the goal. Wiring and jumper are basically difficult to achieve for single and double panels. Therefore, the circuit board will be multi-layered, and due to the continuous increase of signal lines, more power and ground layers are necessary means for design. All of these have made the Multilayer Printed Circuit Board (Multilayer Printed Circuit Board) more common.


For the electrical requirements of high-speed signals, the circuit board must provide impedance control with alternating current characteristics, high-frequency transmission capabilities, and reduce unnecessary radiation (EMI). With the structure of Stripline and Microstrip, multi-layer design becomes a necessary design. In order to reduce the quality problems of signal transmission, insulating materials with low dielectric coefficient and low attenuation rate are used. To cope with the miniaturization and arraying of electronic components, the density of circuit boards is continuously increased to meet demand. The emergence of component assembly methods such as BGA (Ball Grid Array), CSP (Chip Scale Package), DCA (Direct Chip Attachment), etc., has promoted printed circuit boards to an unprecedented high-density state.


Holes with a diameter of less than 150um are called microvias in the industry. Circuits made using the geometric structure of this microvia technology can improve the efficiency of assembly, space utilization, etc., as well as the miniaturization of electronic products. Its necessity.


For circuit board products of this type of structure, the industry has had many different names to call such circuit boards. For example, European and American companies used to use sequential construction methods for their programs, so they called this type of product SBU (Sequence Build Up Process), which is generally translated as "Sequence Build Up Process." As for the Japanese industry, because the pore structure produced by this type of product is much smaller than that of the previous hole, the production technology of this type of product is called MVP (Micro Via Process), which is generally translated as "Micro Via Process." Some people call this type of circuit board BUM (Build Up Multilayer Board) because the traditional multi-layer board is called MLB (Multilayer Board), which is generally translated as "build-up multilayer board".


In consideration of avoiding confusion, the IPC Circuit Board Association of the United States proposed to call this type of product the generic name of HDI (High Density Intrerconnection Technology). If it is directly translated, it will become a high-density connection technology. However, this cannot reflect the characteristics of the circuit board, so most circuit board manufacturers call this type of product HDI board or the full Chinese name "High Density Interconnection Technology". But because of the problem of the smoothness of spoken language, some people directly call this type of product "high-density circuit board" or HDI board.


While electronic design is constantly improving the performance of the whole machine, it is also working hard to reduce its size. In small portable products ranging from mobile phones to smart weapons, "small" is an eternal pursuit. High-density integration (HDI) technology can make terminal product designs more compact, while meeting higher standards of electronic performance and efficiency. HDI is currently widely used in mobile phones, digital (camcorder) cameras, MP3, MP4, notebook computers, automotive electronics and other digital products, among which mobile phones are the most widely used. HDI boards are generally manufactured by build-up. The more build-up times, the higher the technical grade of the board. Ordinary HDI boards are basically one-time build-up. High-end HDI uses two or more build-up techniques, while using advanced PCB technologies such as stacking holes, electroplating and filling holes, and laser direct drilling. High-end HDI boards are mainly used in 3G mobile phones, advanced digital cameras, IC carrier boards, etc.


Development prospects: According to the use of high-end HDI boards-3G boards or IC carrier boards, its future growth is very rapid: the world's 3G mobile phones will grow by more than 30% in the next few years, and China will soon issue 3G licenses; IC carrier board industry consultation The organization Prismark predicts that China's predicted growth rate from 2005 to 2010 is 80%, which represents the direction of PCB technology development.


The continuous growth of mobile phone production is driving the demand for HDI boards. China plays an important role in the world's mobile phone manufacturing industry. Since Motorola fully adopted HDI boards to manufacture mobile phones in 2002, more than 90% of mobile phone motherboards currently use HDI boards. A research report released by market research company In-Stat in 2006 predicted that in the next five years, global mobile phone production will continue to grow at a rate of about 15%. By 2011, global mobile phone sales will reach 2 billion units.


Domestic HDI board production capacity cannot meet the rapidly growing demand. In recent years, the global HDI mobile phone board production situation has undergone major changes: major European and American PCB manufacturers, in addition to the well-known mobile phone board manufacturers ASPOCOM and AT&S, still supply second-order HDI to Nokia In addition to mobile phone boards, most of the HDI production capacity has been transferred from Europe to Asia. Asia, especially China, has become the world's main supplier of HDI boards. According to Prismark's statistics, in 2006, China's mobile phone production accounted for about 35% of the world's total. It is estimated that by 2009, China's mobile phone production will reach 50% of the world's total, and the purchase of HDI mobile phone boards will reach 12.5 billion yuan. From the perspective of major manufacturers, the current production capacity of major domestic manufacturers is less than 2% of total global demand. Although some manufacturers have made investments to expand production, on the whole, the domestic HDI capacity growth still cannot meet the rapidly growing demand.


It can reduce the cost of PCB: When the density of PCB increases to more than eight-layer board, it is manufactured with HDI, and its cost will be lower than that of the traditional and complex pressing process.

Increase circuit density: the interconnection of traditional circuit boards and parts

Conducive to the use of advanced construction technology

Have better electrical performance and signal accuracy

Better reliability

Can improve thermal properties

Can improve radio frequency interference/electromagnetic wave interference/electrostatic discharge (RFI/EMI/ESD)

Increase design efficiency


1. While achieving low defect rate and high output, it can achieve the stable production of HDI's conventional high-precision operation. E.g:

* Advanced mobile phone board, CSP pitch is less than 0.5mm (connection [with or without wires between the disks]

* The board structure is 3+n+3, with three stacked vias on each side,

* 6 to 8 layers coreless pcb printed boards with superimposed vias

In terms of imaging, this type of design requires the ring width to be less than 75mm, and in some cases the ring width is even less than 50mm. Due to alignment issues, these inevitably lead to low production. In addition, driven by miniaturization, lines and pitches are getting finer and thinner—satisfying this challenge requires a change in traditional imaging methods. This can be done by reducing the panel size, or by using a shutter exposure machine for panel imaging in several steps (four or six). Both of these methods achieve better alignment by reducing the influence of material deformation. Changing the panel size has resulted in high material costs, and the use of shutter exposure machines has resulted in low daily output. Neither of these two methods can completely solve the material deformation and reduce the defects related to the photographic plate, which includes the actual deformation of the photographic plate when printing a batch/batch.


2. To achieve the required output by printing the required number of panels every day. As mentioned earlier, the relevant quantity of the required output should be taken into account in the accuracy requirements. To achieve the required output, automatic control is needed to obtain a high output rate.


3. Low cost operation. This is the main requirement for any mass manufacturer. The early LDI mode either required the traditional use of dry film to be replaced with a more sensitive dry film to achieve faster imaging speed; or according to the light source used in the LDI mode, the dry film was changed to a different waveband. In all these cases, the new dry film is usually more expensive than the traditional dry film used by the manufacturer.


4. Compatible with existing processes and production methods. The processes and methods of mass production are usually carefully regulated to meet mass production requirements. The introduction of any new imaging method should have minimal changes to existing methods. This includes minimal changes in the dry film used, the ability to expose each layer of the solder mask, the traceability function required for mass production, and more.