HDI PCB fabrication

HDI PCB fabrication is the core manufacturing service of Rocket PCB, with various functions, qualifications, certification, and expertise to meet the most demanding requirements of HDI PCB fabrication. Our extensive PCB manufacturing capabilities support the stringent requirements for advanced HDI PCB design in all industries, including medical, aerospace, defense, and commercial markets. (See our ability table https://www.rocket-pcb.com/capabilities)

We support up to 40 laminates, laser drilling, micro via holes, stacked micro via holes, blind holes, buried through holes, via- in-pads, laser direct imaging, sequential lamination, 00275 "trace/space, controlled impedance, etc.

Able to produce HDI PCB without minimum order requirements and flexible turnaround time options. Each design is reviewed in detail by our cam engineers before production to ensure that there is no worry about the manufacturing process, and the support team is available 24 hours a week from Monday to Saturday to assist with your HDI PCB fabrication orders.

What is HDI PCB?

HDI is the abbreviation of a high-density interconnector, namely a high-density interconnection board.

HDI board has an inner circuit and an outer circuit, and then uses the technology of drilling and metallization in the hole to realize the internal connection of each layer circuit. Generally, build-up manufacturing is used. The more times of lamination, the higher the technical grade of the board. The common HDI board is basically a one-time build-up, and the high-stage HDI adopts two or more times of lamination technology and adopts advanced PCB technologies such as stack hole, electroplating hole filling, laser direct drilling, etc. With the development of science and technology, electronic design is constantly improving the performance of the whole machine, but also trying to reduce the size. From mobile phones to smart weapons, "small" is the eternal pursuit. High-density integration (HDI) technology can make the design of terminal products more miniaturized and meet the higher standards of electronic performance and efficiency.

 What is the application of HDI PCB?

HDI is widely used in mobile phones, digital cameras, MP3, MP4, notebook computers, automotive electronics, communication systems, network systems, and other digital products, among which mobile phones are the most widely used.

Typical features of HDI PCB

The micro blind hole ring is less than 6mil

the wiring line width between inner and outer layers is less than 4mil and the pad diameter is no more than 0. 35mm.

  • Blind hole: which connects the inner layer with the outer layer.

  • Buried hole: which realizes the connection between the inner layer and inner layer.

All of them are small holes with a diameter of 0. 05mm ~ 0. 15mm.  There are laser drilling, plasma etching, and photo-induced drilling.  Laser drilling is usually used, and laser drilling is divided into CO2 and YAG ultraviolet laser (UV).


How to define the stage of HDI

In the 6 layer laminate, the first stage and the second stage are for the board that needs laser drilling, that is, the HDI board.

The first stage HDI board(1+N+1 HDI)  refers to,

Blind hole: 1-2, 2-5, 5-6, that is, 1-2, 5-6 need laser drilling.

Two-stage HDI PCB (2+N+2 HDI ) refers to,

Blind hole: 1-2, 2-3, 3-4, 4-5, 5-6. First drill 3-4 buried holes, then laminate 2-5, then drill 2-3, 4-5 laser holes for the first time, press 1-6 for the second time, and then drill 1-2, 5-6 laser holes for the second time. Finally, the through-hole was drilled. It can be seen that the 2-stage HDI PCB  has been pressed twice and laser-drilled twice.

In addition, the 2-stage HDI board can also be divided into staggered via  2-stage HDI board and stack via 2-stage HDI board.  Staggered hole 2-stage HDI board means that blind holes 1-2 and 2-3 are staggered, while stacked hole 2-stage HDI board refers to blind holes 1-2 and 2-3 stacked together, such as blind: 1-3, 3-4, 4-6.  So on, the 3-stage and 4-stage are the same.


The production process of HDI PCB

Learn the detailed HDI manufacturing process from our pdf file,  HDI PCB process.pdf.

Advantages of HDI circuit board

  • The cost of PCB can be reduced: when the density of PCB increases more than eight layers, the cost of HDI manufacturing will be lower than that of the traditional complex lamination process.

  • Increase line density: interconnection between the traditional circuit board and parts

  • It is conducive to the use of advanced construction technology

  • Better electrical performance and signal accuracy

  • Good reliability

  • It can improve the thermal properties

  • It can improve radio frequency interference / electromagnetic wave interference / electrostatic discharge (RFI / EMI / ESD)

  • Increase design efficiency


Material of HDI PCB

Some new requirements for HDI PCB materials are proposed, including better dimensional stability, antistatic mobility, and nonadhesive. The typical material of HDI PCB is RCC (resin-coated copper). RCC has three types, namely polyimide metalized film, pure polyimide film, and cast polyimide film.

Advantages of RCC include small thickness, lightweight, flexibility and flammability, compatibility characteristic impedance, and excellent dimensional stability. In the process of HDI Multilayer PCB, the traditional adhesive chip and copper foil can be replaced as the insulating medium and conductive layer.  The traditional suppression technology can be used to suppress RCC. Nonmechanical drilling methods such as lasers are then used to form micro through-hole interconnections.

RCC promotes the emergence and development of PCB products from SMT (surface mounting technology) to CSP (chip-level packaging), from mechanical drilling to laser drilling, and promotes the development and progress of PCB micro through holes.  All of this makes RCC the leading HDI PCB material.

In the actual PCB manufacturing process, there are usually FR-4 standard TG 140C, FR-4 high Tg 170C, and FR-4 and Rogers combination lamination, which are mostly used now. With the development of HDI technology, HDI PCB materials must meet more requirements, so the main trend of HDI PCB materials should be:

  • Development and application of flexible materials without binder;

  • The thickness of the dielectric layer is small, and the deviation is small;

  • The development of LPIC;

  • The dielectric constant becomes smaller and smaller.

  • The dielectric loss is getting smaller and smaller.

  • High welding stability;

  • Strictly compatible with CTE (coefficient of thermal expansion);

HDI technology - Manufacturing Difficulties

The difficulty of HDI PCB manufacturing lies in micro hole manufacturing, through-hole metallization and thin wire.

Micro-via hole manufacturing

Micro via manufacturing has always been the core issue of HDI PCB manufacturing. There are two main drilling methods:

  • For ordinary through-hole drilling, mechanical drilling is always the best choice for its high efficiency and low cost.

  • There are two types of laser drilling: photothermal ablation and photochemical ablation. The former refers to the process of heating the operating material after high energy absorption of laser to make it melt and evaporate through the formed through-hole. The latter refers to the results of high-energy photon and laser length exceeding 400 nm in the ultraviolet region.

  • There are three types of laser systems for the flex-rigid board: excimer laser, UV laser drilling, CO2 laser. Laser technology is not only suitable for drilling, but also suitable for cutting and forming. Although the cost of laser drilling equipment is high, they have higher precision, stable technology, and mature technology. The advantages of laser technology make it the most commonly used method in blind / buried hole manufacturing. Today, 99% of HDI micro via holes are obtained by laser drilling.

Through-hole metallization

The biggest difficulty of through-hole metallization is the difficulty of uniform plating. For the deep hole electroplating technology of micro through-hole, in addition to using electroplating solution with high dispersion ability, the plating solution on electroplating device should be upgraded in time, which can be achieved by strong mechanical stirring or vibration, ultrasonic stirring, and horizontal spraying. In addition, the humidity of the through-hole wall must be increased before electroplating.

In addition to the process improvement, HDI through-hole metallization method also saw the main technical improvements: electroless plating additive technology, direct plating technology, etc.

Thin line

The realization of the thin lines includes traditional image transmission and laser direct imaging.

For laser direct imaging, there is no need for photographic film, and the image is directly formed on the photosensitive film by laser. UV wave lamp is used for the operation to avoid adverse effects caused by film defects.  It can be directly connected to CAD / CAM to shorten the manufacturing cycle and make it suitable for limited and multiple small-batch PCB production.

HDI PCB from Rocket PCB

Rocket PCB has advanced advantages in HDI PCB fabrication, advanced technology, and advanced equipment to ensure that we can produce advanced HDI PCB. Want to know how much will your HDI PCB fabrication cost? Feel free to submit a quote request on this page with a detailed description of your HDI PCB requirements. We will quote your HDI PCB very quickly.

Learn more information about HDI PCB,

What is HDI board

A brief primer on HDI pcb manufacturing

Design challenges of high speed HDI

What should be considered in HDI design

HDI PCB in automotive electronic

High-end HDI anylayer mass production capacity-Rocket PCB

HDI PCB fabrication

Tel: (+86) 159 1680 5427

Tel: (+86) 158 9965 5195

E-mail: sales@rocket-pcb.com

Skype: Hans@Rocket-PCB

Whatsapp: 86 1589965 5195

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