How LCP Materials Empower Hybrid Power PCU Electronic Control Modules?

The automotive industry is currently in an era of transformation. Against the backdrop of increasingly severe global environmental issues, energy-saving and clean emission regulations are becoming more stringent. To meet these challenges, major automakers are accelerating the development of hybrid electric vehicles, pure electric vehicles, fuel cell vehicles, and other drive systems to replace traditional internal combustion engines. Among them, hybrid electric vehicles (HEVs) with both gasoline engines and drive motors as power sources have taken the lead in commercialization and popularization.

As the largest automotive parts supplier under Honda Motor Co., Ltd., Keihin Corporation has taken the lead in researching and developing next-generation drive system components as a provider of comprehensive energy management system solutions. As early as October 2015 at the Tokyo Motor Show, Keihin released its independently developed new Power Control Unit (PCU) — a motor unit for controlling power generation and driving in hybrid vehicles. In November of the same year, it started mass production of the core component, the Intelligent Power Module (IPM), which has been installed in Honda's "ODYSSEY Hybrid."

The miniaturization and high-performance of IPM have promoted the overall miniaturization and lightweight of PCU. One of the key technologies supporting this breakthrough is the LAPEROS® LCP S135 resin material from Polyplastics.

Ⅰ. Working Principles of PCU and IPM

As the core of power regulation in hybrid vehicles, the PCU can convert battery voltage into the working voltage of the drive motor, regulate the motor's driving force during cruising and acceleration, and is responsible for DC current conversion when the generator charges the battery, as well as recovering energy generated during deceleration. Its structure includes a boost transformer, motor drive and feedback controller, intelligent power module, etc.

As the core semiconductor composite component of the PCU, Keihin has achieved the highest power output density of the PCU by reducing the thermal loss of IGBT (Insulated Gate Bipolar Transistor) and feedback diodes, combined with the design of a high-temperature resistant and miniaturized cooling structure. The IPM is located at the center of the PCU, with a gate drive substrate mounted above and a water-cooled jacket below. The size of its housing directly determines the overall volume of the PCU — Keihin has achieved the overall miniaturization of the PCU through technological innovation of IPM components.

Ⅱ. Technological Breakthroughs of LAPEROS® LCP S135 in IPM Housing

Excellent Solder Welding Heat Resistance

During IPM manufacturing, the housing must withstand the high temperatures of the solder welding process. The glass fiber-reinforced grade of LAPEROS® LCP S135 has become a key material in the industry for achieving IPM miniaturization and high power output due to its superior heat resistance — its performance ensures that the resin surface remains stable during high-temperature processes, avoiding deformation or damage.

Balance of High Fluidity and Fusion Strength

As the largest molded product made of LAPEROS® LCP resin, the IPM housing must meet the fluidity requirements for large-scale molding while achieving the precision standards of intricate components such as connectors. The densely arranged Busbar copper sheets in the housing need to be integrally molded with the resin without adhesives, posing extremely high challenges to the molding process. Through the flow analysis data support from Polyplastics' TSC Technology Center and the tripartite data sharing among Keihin and molding manufacturers, the problem of heating cracks in the fusion zone was finally overcome.

Dimensional Stability and Warpage Control

The IPM needs to be mounted on a water-cooled jacket, and its shape accuracy directly affects the cooling effect. LAPEROS® LCP S135 has effectively controlled warpage through flow analysis data optimization and the process experience of molding manufacturers, ensuring no gaps between the IPM and the water-cooled jacket to guarantee heat dissipation performance.

Comprehensive Advantages of Heat Resistance and Reliability

Although LCP materials have higher costs and greater molding difficulties, in IPM manufacturing, other materials are prone to problems such as bulging, while LAPEROS® S135 stands out in heat resistance and reliability, becoming the only choice. As PCUs upgrade towards smaller size and higher performance, the requirements for material heat resistance in IPM will further increase, and the advantages of LCP materials will continue to be highlighted.

Ⅲ. Vibration Damping Principle of LCP Materials

The polymer molecules of LAPEROS® have a strongly oriented internal structure, and this orientation forms a layered arrangement in the molded product. When the molded product is subjected to vibration, the friction between the layered structures rapidly dissipates vibration energy, significantly enhancing its vibration damping performance.

Ⅳ. Technological Extension and Future Applications

As a semiconductor composite component, IPM manufacturing must be completed in a super clean room. Keihin has built a Class 10,000 clean room at its Miyagi Second Manufacturing Plant, introducing new chip mounting lines and advanced analysis technologies to promote the application expansion of IPM in new-generation power systems such as hybrid vehicles, electric vehicles, and fuel cell vehicles, providing core technical support for the electrification of automobiles.