With the arrival of 5G, smaller and more compact devices are necessary to support the increased data transmission speeds and bandwidth. Manufacturers are actively working on developing smaller antennas, chips, and other components to meet these demands.

Packaging technologies, such as system-in-package (SiP) and wafer-level packaging (WLP), are being utilized to achieve higher integration of components in smaller form factors. This allows for greater efficiency and performance in miniaturized devices.

Materials advancements, including low-loss dielectric substrates and high-frequency circuit materials, are also being pursued to improve signal integrity and reduce energy consumption in compact 5G devices.

The first large-scale deployment of 5G infrastructure began in 2019, coinciding with the introduction of smartphones equipped with 5G capabilities. While the widespread rollout of true millimeter-wave (mmWave) 5G has been progressing slowly, some of the largest wireless component manufacturers have already started offering products that support both Sub-6 GHz and mmWave access. It is anticipated that users will increasingly access mmWave spectrum, leading manufacturers to focus on introducing components that operate in dual-band to support low, mid, and high-frequency 5G networks.

Currently, 5G is moving towards higher operating frequencies to achieve higher data rates and lower latency. Faced with the design challenges posed by higher frequencies, system designers and product engineers must rely on more specialized components to address these challenges.

 

What happens in higher-frequency 5G systems?

Devices operating at higher frequencies will experience greater signal loss, requiring design engineers to potentially redesign any components that interact with the 5G signal. Connectors, antennas, cables, and enclosures are all components that interact with the transmitted or received 5G signals. The components and materials commonly used in deployed 4G systems may not always be compatible with the higher frequencies used in 5G infrastructure and devices.

 

Some of the key factors driving miniaturization in design include:

1. Higher antenna density for high-frequency antenna arrays: High-frequency antenna arrays require a higher density of antennas to achieve the desired performance, leading to the need for smaller antenna sizes and more compact designs.
2. Increased battery capacity for 5G connectivity: 5G connectivity demands higher power consumption, requiring larger physical-sized batteries. This occupies more space within the devices, driving the need for miniaturization of components to accommodate the larger battery size.
3. Emergence of alternative packaging strategies and materials for RF components: To meet the demands of 5G systems, alternative packaging strategies and materials for RF components are being explored. These strategies aim to achieve smaller form factors and improved performance in high-frequency applications.
4. Higher feature density requirements for 5G-enabled devices: 5G-enabled devices often require higher feature density, meaning more functionalities and components are integrated into a smaller space. This drives the need for miniaturization of components to meet the size constraints while maintaining performance.

antenna array

As 5G devices are wireless, antennas are obviously essential components. The size of antenna arrays becomes smaller as the frequency increases, as their operating frequency is inversely proportional to their size. This requires manufacturers to reduce the size of antenna arrays, presenting challenges in circuit board etching for PCB manufacturers and packaging difficulties for antenna module and modem manufacturers, as well as component manufacturers. The size reduction poses manufacturing difficulties and challenges for connector designs that support the required signal bandwidth with solder pad patterns.

For component manufacturers, supporting millimeter-wave antenna arrays requires smaller components. This is beneficial for system/product designers as it frees up space on the circuit board for other components.

The antenna arrays used in 5G-enabled smartphones are typically 2×2 patch antenna arrays. Due to the smaller size of these arrays, manufacturers need to employ additive methods when fabricating components for millimeter-wave range. Using lower dielectric constant (DK)/lower loss materials can overcome manufacturing limitations. However, ultimately, 5G/6G antenna arrays will reach manufacturing limits where reliable fabrication cannot be achieved with standard and additive processes beyond those limits.

 

Board-to-board connectors and flexible flat cable (FFC) connectors：

Interconnections between circuit boards and components are made using ready-made connectors or custom connectors. In the past, connectors with coaxial cable connections were commonly used for millimeter-wave systems, which was often the only method of signal transmission within the 5G frequency range. However, for mobile phones, smaller connectors are required as there is limited space to accommodate bulky coaxial connectors and cable assemblies. As a result, the industry has adopted surface-mount flexible flat cable (FFC) connectors for board-to-board and FFC-to-board connections.

In mobile phones, board-to-board and FFC connectors have extremely compact form factors, requiring component stacking or connection to flexible ribbon cables. These thin-profile connectors typically need to handle power and digital signal circuits, and may also transmit RF signals.

To accommodate the size of PCBs and their associated operating frequencies (data and RF), the industry has had to use smaller board-to-board and FFC connectors. This is a major driving factor for miniaturization in this area. Smaller connectors necessitate smaller solder pad patterns that ensure signal integrity, thus providing more space for components and batteries. These systems may use terminal pitches smaller than 0.5 millimeters, operate within the millimeter-wave range, and ensure no signal loss to the PCB substrate.

Coaxial cables and connectors

Coaxial cables and connectors are used in RF equipment, where their form factor is not the main challenge. Instead, they need to have high power handling capabilities while minimizing losses due to dispersion and other factors. While standard larger-sized connectors like SMA connectors can be used with wideband connector pads at millimeter-wave frequencies, smaller-sized connectors with higher feature density are required in compact layouts, surpassing size limitations and operating in the millimeter-wave range. Custom connectors can be developed when off-the-shelf components do not meet the specified form factor requirements.

Another challenge in 5G systems is passive intermodulation (PIM), which can interfere with data transmission in carrier aggregation wireless systems. PIM is sometimes referred to as the “rusty bolt effect,” and connectors can be a source of PIM. Even a small amount of PIM near the carrier frequency can cause errors that reduce the data transmission rate.

Some smaller or custom connectors can provide lower PIM values, which is crucial for systems operating at higher frequencies. As the signal loss (packet loss) increases in millimeter-wave frequencies, the system’s link efficiency decreases, and the allowable PIM specification becomes lower. Therefore, smaller-sized connectors and cable assemblies may be required to minimize the chances of PIM occurrence.

 

Small-sized components and other specifications.

Small-sized components used in mobile phones, mini-cellular devices, and 5G-enabled modules adhere to a separate set of specifications, which become more complex due to the reduction in component size. As the need arises for smaller components to accommodate higher frequencies, mechanical design and durability issues for these components become intricate. Mobile phones and cellular devices must operate in harsh environments and varying temperatures while maintaining continuous functionality. Therefore, components must meet the following environmental specifications:

Environmental specifications:

• Wind and waterproofing: Components exposed to the environment, particularly connectors, may require protection at the IP6x level to ensure reliability.
• Connector retention: Grasping mechanisms help prevent unintended disconnection of connectors within the system caused by vibration or mechanical shocks.
• Integrated connectors: In smaller devices with limited space, accommodating multiple connectors becomes challenging. Therefore, a single cable may contain both power and signal pins.

5G designers choose Sinrui for the following reasons:

Sinrui provides a range of engineering solutions and components for 5G systems, including connector solutions. They engage in collaborative system design, offering expertise in testing and customized component design to assist customers in the mass deployment of 5G products. Sinrui aims to produce high-volume, cost-effective products that are compatible with the form factor requirements of the telecommunications, IoT, and automotive markets. While the industry transition to 5G presents complexities, Sinrui helps facilitate a smoother transition by offering solutions that address the unique challenges of 5G design and production.