HDs and Hybrids Pack More Electronics in Smaller Form Factors

By Contributed Article | April 08, 2025

As AI and IoT continue to evolve, the miniaturization of components will play a critical role in making these technologies more accessible and easier to integrate into our daily lives. OEMs are looking for ways to pack more functionality into increasingly smaller smart devices.

The progression of Internet of Things (IoT) and artificial intelligence has changed the way we interact with everyday objects. From automotive and automation to wearables and washing machines, IoT and AI form a powerful combination that enables devices to not only collect and transmit data, but act on that information — in real time. AI algorithms can analyze vast amounts of data generated by IoT sensors, allowing devices to make intelligent decisions without human involvement. For example, smart thermostats can learn from user behavior and environmental conditions to optimize heating and cooling, resulting in energy savings and improved comfort.

As AI and IoT continue to evolve, the miniaturization of components will play a critical role in making these technologies more accessible and easier to integrate into our daily lives. OEMs are looking for ways to pack more functionality into increasingly smaller smart devices. This includes adding displays, switches, sensors, actuators, communication modules, memory and more.

High-density and hybrid connectors enable more functionalities in smaller footprints. Miniature high-density connectors provide more contacts in a compact area (pitch) to support higher data rates. Hybrid board-to-board connectors combine power and signal into a single, space-saving format. However, as devices become smaller, OEMs face design challenges that can affect performance. Key considerations include:

Thermal management in tightly packed designs
Signal integrity and EMI/EMC concerns
Reliability and durability in compact form factors
Manufacturability and assembly processes

With a 0.35mm pitch, 0.6 mm height and a width of 1.5 mm, Hirose’s BM29 Series is the world’s smallest board-to-board connector.

Miniaturization and heat issues

Excessive heat can cause electronic components, such as connectors, to malfunction or fail entirely. In miniaturized IoT devices, smaller size and higher component density lead to heat buildup in confined areas, resulting in localized hotspots and elevated internal temperatures. This can impact both performance and reliability.

Compact designs with high-density connectors leave little room for traditional cooling methods like heat sinks or fans. Limited internal space restricts airflow, making effective heat dissipation more difficult. Using connectors with high-temperature ratings helps ensure reliable performance and long-term operations under these conditions.

Hirose DF40 Series 0.4mm Pitch, 1.5 to 4.0mm Height, Board-to-Board and Board-to-FPC Connectors

SI and EMI issues

Miniaturization significantly affects signal integrity (SI) and electromagnetic interference (EMI). Closer proximity between traces increases the risk of electromagnetic coupling and signal interference, also known as crosstalk. Shorter traces and tighter bends can create impedance discontinuities and mismatches, leading to signal reflections and degradation. In addition, smaller conductors and thinner PCB layers can increase signal attenuation, reducing signal strength.

Compact designs also limit space for proper shielding and grounding, making devices more vulnerable to external EMI and less able to contain internal emissions. Small power distribution networks can generate noise and EMI when switching power supplies.

The shift to 5G has further impacted compact IoT device designs. Operating at much higher frequencies (up to 39 GHz or more), 5G increases the challenges of SI and EMI due to greater susceptibility to signal loss and attenuation. Increased bandwidth also makes devices more vulnerable to electromagnetic interference.

To address these issues, designers must use advanced PCB layout techniques, careful connector selection, and implement innovative shielding solutions. High-density and mezzanine connectors are often utilized in miniature IoT designs to preserve signal integrity and minimize EMI.

Application Examples

As connected consumer and medical monitoring devices become more sophisticated, they require faster data processing and more efficient power systems for longer battery life. Hybrid connectors, like the BM29 Series, support both communication and power transfer between different components within a wearable device. By combining signal and power into one multi-functional connector, manufacturers can add more functionality without increasing device design.
Hybrid connectors can also be customized to meet specific device requirements. This includes selecting the types and number of connections, while considering factors like impedance matching, signal integrity, and power distribution.

Hirose’s FX23 floating BTB connector

Designed for densely populated systems that require multiple connectors to be used on the same two boards, miniature board-to-board connectors that feature a floating contact system simplify assembly and reduce labor costs, all while offering space savings. Floating contacts allow the connector to absorb various amounts of alignment errors or vibration. These floating board-to-board connectors, like the hybrid FX23/FX23L, exhibit a floating range of ± 0.6 mm in both the X- and Y-axis direction, as well as ± 0.75 mm tolerance between boards in the Z direction. This floating feature prevents misalignment during board installation and mounting. Because the spring portion of the terminal absorbs assembly errors, it reduces the need for corrective re-work operations. Connectors with a floating contact design provide superior vibration resistance for more reliable operation. The floating contact system increases reliability by reducing the stress on solder joints caused by misaligned connectors. The floating design also enhances durability by preventing solder cracking. Board-to-board connectors meet further smart product requirements by combining high data rate capabilities, EMI shielding, and a small footprint with a 0.5 mm pitch.

The floating design of Hirose’s BTB/board-to-FPC connector offers a degree of “play” between the contacts during mating and allows the connector to absorb alignment errors and simplify assembly.

Smart home technologies now go far beyond the AI speaker. Devices like smart locks, lighting systems, thermostats, and security setups all rely on high-frequency, high-speed connectors to support the latest connectivity protocols for IoT and M2M communication. High-density connectors provide more contacts in a smaller area (pitch) to support higher data rates with minimal latency in a smaller package. This enables manufacturers to deliver smaller, more capable end-products. For example, the DF40 board-to-FPC connector supports USB4 Gen2 (10 Gb/s) with a 0.4 mm pitch, 3.68 mm mounting depth, and a mating height range of 1.5 to 4.0 mm. The DF40 family also offers options for high temperature, positive locking, EMC shielding, and versions with or without retention tabs.

Driven by AI and IoT technologies, smart product systems are becoming more advanced and feature-rich, adding a wide range of new functions in compact form factors. From increased data rates to more efficient power systems, smart devices rely on a variety of connectors to meet application requirements. Connector manufacturers are empowering OEMs to create more sophisticated, compact, and efficient smart devices. As the demand for smarter, more connected devices continues to grow, advanced connector solutions will play a pivotal role in shaping the future of smart device integration.

To learn more, visit Hirose Electric Americas.

Article Contributed by Hirose