Why are high-level HDI boards often used in high-end electronic products? What are the differences between them and ordinary PCB boards?

With the rapid development of smart phones, tablets, wearable devices, servers, automotive electronics, and artificial intelligence hardware, the performance requirements for circuit boards in electronic products are becoming increasingly higher. Many high-end electronic devices internally adopt high-order HDI boards, while traditional electronic products mostly use ordinary PCB boards. So, what exactly is a high-order HDI board? Why can it become an important component of high-end electronic products? And what are the essential differences between it and ordinary PCB boards?

What is a high-level HDI board?

HDI is the abbreviation of "High Density Interconnect", which is known as a high-density interconnection circuit board in Chinese. A high-level HDI board is a high-end PCB product that is manufactured based on the ordinary HDI technology through multiple hole-laying techniques, laser micro-hole technology, and higher-level circuit design.

In simple terms, an ordinary PCB is like an ordinary road in a city, while a high-level HDI board is more like a modern city with a three-dimensional transportation network. It can achieve more line connections within a limited space, thus meeting the demands for miniaturization and high integration of high-performance electronic products.

The common HDI boards currently available in the market can be classified as follows:

First-generation HDI board

Second-order HDI board

Third-generation HDI board

Fourth-order and higher-order HDI boards

In the industry, products with a design hierarchy of three or above are referred to as high-level HDI boards.

Why are high-end electronic products increasingly relying on high-grade HDI boards?

1. Meeting the demand for lightweight and thin products

Nowadays, consumers' requirements for electronic products are not only about having rich functions, but also they expect devices to be thinner and lighter.

For example:

Smartphone

Smartwatch

AR glasses

Tablet computer

The internal space of these devices is extremely limited, and a large number of chips, sensors and functional modules need to be integrated within such a small area.

High-level HDI boards can achieve more circuit connections within a limited area by using finer lines, smaller hole diameters and higher wiring density.

Therefore:

Under the same functionality, high-end HDI boards can make the product size smaller.

2. Support for high-performance chip packaging

As chip manufacturing processes continue to advance, the number of chip pins is increasing.

For example:

CPU

GPU

AI chip

5G baseband chip

These high-end chips are usually packaged using BGA technology.

If ordinary PCB boards are used, it is often difficult to complete the design of complex pin-outs.

The high-level HDI board features:

Laser micropore technology

Any-layer interconnection technology

Multi-level blind hole structure

It can easily meet the requirements of ultra-high-density pin routing.

Therefore, almost all high-end chip platforms rely on high-level HDI boards.

3. Improve signal transmission quality

High-frequency and high-speed electronic products have extremely high requirements for signal integrity.

For example:

5G communication equipment

AI server

High-speed switch

Data center equipment

If the line is too long or the impedance control is unstable, the following situations are likely to occur:

Signal attenuation

Crosstalk

Reflection

Data loss

High-level HDI boards can achieve:

Shorter route design

More precise impedance control

More reasonable stacking structure

This thereby improves the efficiency and stability of signal transmission.

4. Enhance product reliability

High-end electronic devices usually require long-term stable operation.

For example:

Automotive Electronics

Medical equipment

Industrial Control System

Aerospace equipment

After adopting advanced manufacturing techniques, the high-level HDI board:

Better conduction performance

Higher thermal stability

Higher vibration resistance capability

Capable of adapting to complex working environments.

What are the differences between high-end HDI boards and ordinary PCB boards?

The structural complexity is different.

Ordinary PCBs usually adopt:

Double-layer board

Four-layer board

Six-layer board

The structure is relatively simple.

High-end HDI boards may reach:

10th floor

12th floor

Sixteen floors

Above the 20th floor

Also include:

Blind hole

Burial hole

Micropores

Stacking holes

The complexity of the structure is much higher than that of an ordinary PCB.

The wiring density is different.

The width of the ordinary PCB lines is usually:

4mil

5mil

6mil

High-end HDI boards can achieve:

3mil

2mil

Even more detailed

The layout is more compact.

At the same area:

High-level HDI boards can achieve more circuit connections.

Different aperture sizes

Mechanical drilling for ordinary PCBs:

0.15 millimeters

0.2 millimeter

Above 0.3mm

High-level HDI boards use laser drilling:

0.075 mm

0.06 millimeters

Even smaller

The microporous technology can effectively save space.

Different manufacturing processes

Main processes of ordinary PCB:

Cutting the material

Pressing and bonding

Drilling

Electroplating

Etching

The high-level HDI board has added:

Laser drilling

Repeated pressing

SAP semi-addition process

Precise exposure process

Any-layer interconnection technology

The technical difficulty has significantly increased.

Production costs vary

Due to the increased difficulty in manufacturing:

The cost of high-end HDI boards is significantly higher than that of ordinary PCBs.

The factors influencing costs include:

Number of laser drilling holes

Number of pressing operations

Number of layers

Material grade

Process yield control

In general:

The price of high-end HDI boards can be several times or even more than ten times that of ordinary PCB boards.

In which fields are high-level HDI boards mainly applied? Smartphone

The mainboards of flagship mobile phones generally adopt advanced HDI technology.

The reasons include:

High space utilization rate

Support multi-camera system

Support for 5G module layout

Artificial intelligence equipment

The AI servers and AI acceleration cards have a large demand for high-speed signal transmission.

High-level HDI boards can:

Reduce signal loss

Improve computational efficiency

Automotive electronics

The degree of electrification in new energy vehicles is increasing steadily.

Typical applications include:

ADAS Autonomous Driving Assistance System

Autonomous Driving Domain Controller

Battery Management System

Intelligent Cockpit

All these modules require high-reliability HDI boards for support.

Medical electronics

Medical equipment has extremely high requirements for stability.

For example:

CT equipment

Ultrasound equipment

Medical monitoring equipment

High-end HDI boards can ensure long-term stable operation.

Communication equipment

5G base stations, switches and routing devices all adopt high-density PCB designs.

High-level HDI boards can meet the following requirements:

High frequency

High speed

High integration

A number of other requirements.

How to determine whether a PCB factory has the capability for high-end HDI manufacturing?

When choosing a high-end HDI supplier, the following indicators can be given priority attention:

Does the company have experience in mass production of multi-stage HDI?

Key points to be examined:

Third-order HDI

Fourth-order HDI

Any-layer HDI

Project Case.

Do you have laser drilling equipment?

The precision of laser drilling directly affects the quality of the product.

Does it have the production capacity for high-rise boards?

High-order HDI usually involves:

Above the 12th floor

Repeated pressing

The process has relatively high requirements.

Does it have high reliability certification?

For example:

ISO9001

IATF16949

ISO13485

UL Certification

These certifications can reflect the manufacturing capabilities of the enterprise.