Why is the soft-hard composite board becoming increasingly popular? What advantages does it have compared to traditional PCBs?

With the rapid development of industries such as smart phones, wearable devices, medical electronics, new energy vehicles, and aerospace, electronic products are constantly upgrading towards being thinner, smaller, and more highly integrated. Although traditional PCBs can meet the needs of most electronic products, they are gradually facing challenges in terms of space utilization, structural design, and reliability.

In this context, the rigid-flex printed circuit board (Rigid-Flex PCB) has gained popularity as an important choice for a growing number of high-end electronic products due to its unique structural advantages. So, why has the rigid-flex PCB become increasingly popular? And compared to traditional PCBs, what are its distinct advantages?

What is a soft-hard hybrid board?

A soft-hard hybrid board is a type of circuit board that connects a rigid PCB and a flexible FPC together through a special process.

In simple terms:

The hard plate section is responsible for component installation and the supporting structure.

The soft panel section is responsible for bending connections and spatial extension.

The two are formed into a complete whole through the laminating process.

Therefore, it possesses both the stability of a hard board and the flexibility of a soft board.

Common structures include:

Two-layer soft-hard composite board

Four-layer soft-hard composite board

Six-layer soft-hard composite board

Multi-layer soft-hard composite board

With the advancement of technology, complex products can even achieve structural designs with more than ten layers.

Why are soft and hard composite boards becoming increasingly popular?

Electronic products are becoming thinner and lighter.

Nowadays, consumers have higher and higher requirements for electronic products.

Not only do we hope for powerful functions, but also:

Lighter

Thinner

Smaller in size

For example:

Smartphone

Smartwatch

Bluetooth headphones

AR glasses

The interior space is extremely limited.

Traditional PCBs usually require:

Connector

Cable assembly

Cable assembly

Realize the connection of different modules.

These structures will occupy a large amount of space.

The soft-hard combined board can directly achieve three-dimensional interconnection.

Effectively save internal space.

The product functions are becoming increasingly complex.

Modern electronic products incorporate a large number of functional modules inside.

For example, a smart phone might contain:

Motherboard

Camera module

Display module

Battery Management System

Antenna system

If the traditional connection method is adopted:

The structure will be extremely complex.

The soft-hard combined board can achieve:

Multi-regional integrated design.

Reduce the overall complexity of the structure.

The requirements for reliability are constantly increasing.

For traditional PCBs and wire connections, the usual procedure is:

Plug and unplug the connector

Welding connection

After long-term use, the following may occur:

Poor contact

Loosen

Oxidation

The soft-hard combined board adopts an integrated structural design.

Reduce the number of connection points.

Significantly enhance the system's reliability.

What are the advantages of the soft-hard hybrid board compared to traditional PCBs?

Advantage 1: Saving installation space

This is the most obvious advantage of the soft-hard hybrid board.

Traditional PCB connection method:

Motherboard

↓

Connector

↓

Cable assembly

↓

Functional Module

The entire connection system takes up a considerable amount of space.

And the soft-hard combined board can directly connect different areas.

Reduce:

Socket

Connector

Cable assembly

Make the product structure more compact.

Therefore, it is widely applied in ultra-thin electronic products.

Advantage Two: Achieving Three-Dimensional Design

Traditional PCBs are of planar structure.

The layout is restricted.

The soft-hard composite board can:

Fold

Bend

Flip

Realize the three-dimensional spatial layout.

For example:

The mainboard inside smart phones often adopts a folded structure.

Make full use of the limited space.

This is something that is difficult to achieve with ordinary PCBs.

Advantage Three: Enhancing Product Reliability

Statistical data show:

A significant portion of electronic equipment malfunctions are caused by connector issues.

For example:

Poor contact

Mechanical wear and tear

Plug-in damage

The combination of soft and hard materials reduces the intermediate connection steps.

Advantages include:

Fewer solder joints

Fewer connectors

Less exposure to malfunctions

Therefore, the reliability has significantly improved.

Especially applicable to:

Medical equipment

Automotive Electronics

Avionics

The field of high reliability.

Advantage 4: Reducing product weight

Traditional PCB with traces:

Usually required:

Connector housing

Metal terminal

Fixed structure

Increase the weight.

The soft-hard combined board integrates multiple components into a single unit.

It can significantly reduce the weight of the product.

Regarding:

drone

Aviation equipment

Wearable devices

Has obvious advantages.

Advantage Five: Enhance Anti-Vibration Capability

Automotive electronics and industrial equipment typically encounter:

High-frequency vibration

Temperature variation

Long-term operation

Traditional connectors are prone to contact problems due to vibrations.

The soft-hard combined board adopts a flexible connection structure.

Capable of absorbing mechanical stress.

Improve system stability.

Advantage 6: Enhance assembly efficiency

The traditional solution requires:

Install the connector

Connector cable

Fixed wiring harness

There are many processes.

The soft-hard composite board can typically achieve:

One installation.

Reduce the assembly steps.

Improve production efficiency.

Reduce labor costs.

Advantage 7: Facilitates High-Speed Signal Transmission

With the development of 5G, WiFi 7 and high-speed data interfaces.

Electronic devices have increasingly higher requirements for signal integrity.

Traditional connectors may bring about:

Change in impedance

Signal reflection

Increased crosstalk

The soft-hard composite board can:

Shorten the transmission path

Reduce the number of connected nodes

Improve impedance continuity

It is conducive to the stable transmission of high-speed signals.

Which industries does the soft-hard composite board mainly apply to?

Consumer electronics

Typical products include:

Smartphone

Tablet computer

Smartwatch

Bluetooth headphones

AR/VR devices

This is the field that is currently the most widely applied.

Medical equipment

Applications include:

Endoscope

Medical monitoring equipment

Ultrasound equipment

Implantable medical devices

High reliability and miniaturization design are required.

Automotive electronics

Main applications:

ADAS system

Vehicle-mounted camera

Intelligent Cockpit

Instrumentation system

Meet the requirements of complex environments.

Aerospace

Aircraft equipment emphasizes:

Lightweighting

High reliability

The combination of soft and hard materials enables the board to significantly reduce its weight while enhancing its stability.

Industrial Automation

Complex control systems increasingly adopt the design of combining hardware and software components.

Improve the utilization rate of space.

Is there any deficiency in the combination of soft and hard materials?

Although it has obvious advantages, it also faces some challenges.

For example:

The manufacturing cost is high.

The process is complex.

The material cost is higher than that of ordinary PCBs.

The design is quite challenging.

It requires considering the following aspects simultaneously:

Rigid board design

Flexible area design

Flexural life

The requirements for design engineers are quite high.

The production cycle is long.

Involves:

Processing of flexible materials

Repeated pressing

Precise alignment

The production process has become more complicated.

The development trend of hybrid boards in the future

In the coming years, the demand for hybrid boards will continue to grow.

The main driving factors include:

AI intelligent terminal For example:

AI glasses

AI wearable devices

New energy vehicles

The autonomous driving system requires a more integrated design.

Medical electronics

The demand for portable medical devices is increasing.

Aerospace and aviation

The demand for lightweighting continues to increase.