Exploration of the Application of High Damping PPS Material in Vibration Reduction of Electronic Control Systems

1、 Introduction: An overlooked performance dimension

Polyphenylene sulfide（PP）Due to its excellent heat resistance, chemical corrosion resistance, and dimensional stability, it has been widely used in fields such as new energy vehicle electronic control systems and electrical connectors. However, there is a performance dimension that has long been overlooked by the industry——Damping performance.

Damping, the ability of a material to absorb vibrational energy, is typically measured by the loss factor (tan δ). For electrical components installed in vibration environments, whether it is the junction box around the engine, the connector near the motor, or the inverter housing integrated on the electric drive assembly, the damping ability of the material directly affects the contact stability of the terminals, the fatigue life of the solder joints, and even the long-term reliability of the entire system.

Unfortunately, conventionalPPSThe loss factor at room temperature is extremely low. Industry research shows that although PPS has a high loss factor at higher temperatures (such as above 100 ° C), its loss factor is very low in the normal temperature range of 100 ° C and below. This means that when vibration is transmitted to the junction box or connector made of PPS, almost all of the vibration energy is transferred to the internal terminal contacts or solder joints, and long-term accumulation may lead to contact looseness, increased resistance, heating, and even ablation.

The industry is not unaware of this issue. In the motorcontrollerIn applications such as high-voltage connectors, engineers usually compensate for the insufficient damping of the material itself by adding rubber gaskets and optimizing structural design. But these solutions increase the number of parts, assembly processes, and costs, and the vibration reduction path depends on the external structure rather than the intrinsic properties of the material. If this problem can be solved from the material level, it will provide a new degree of freedom for the vibration reduction design of electronic control systems.

Wolf Chemical has continuously explored and validated in this direction, and now shares its preliminary results with industry colleagues.

　2、 Industry Status: Damping Shortboard of Conventional PPS

Why is the damping of regular PPS low?

The PPS molecular chain is composed of alternating benzene rings and sulfur atoms, with a highly regular structure and a crystallinity typically ranging from 50% to 60%. This ordered structure endows PPS with excellent rigidity and heat resistance, but also brings a side effect:

Restricted molecular chain movement: At room temperature, PPS molecular chains are in a "frozen" state, making it difficult to dissipate vibration energy through internal friction between molecular chains

The loss factor is extremely low: at room temperature, tan δ is usually only 0.001~0.06, which basically does not have the ability to reduce and absorb vibrations

The temperature dependence is obvious: the damping performance of PPS only significantly increases at higher temperatures, but this has exceeded the normal temperature working range of most electrical components

2.2 Industry Status

At present, there is no widespread attention paid to the damping performance of PPS insulation materials for motor and electronic control in the industry, and it is generally believed that PPS materials are like this.

2.3 Unsatisfied Needs

Against the backdrop of the development of new energy vehicle electronic control systems towards high integration and high power density, components such as inverter housings, junction boxes, and connectors are facing increasingly stringent vibration conditions. There is a clear and urgent demand in the industry for materials that maintain the inherent advantages of PPS while also possessing good damping capabilities. The larger the damping coefficient, the weaker the structural vibration and the lower the noise, which has a direct significance for improving the overall NVH performance of the vehicle.

3.1 Design Ideas

The Wolf team has gradually developed a set of "multiphase structure design" ideas through long-term functional PPS modification practice. The core idea is to construct microscale "energy dissipation units" in PPS matrix, so that the material can efficiently convert mechanical energy into thermal energy and dissipate it when subjected to vibration.

Specifically, this design concept includes the following levels:

(1) The matrix remains continuous

PPS, as a continuous phase, ensures that the overall heat resistance, chemical resistance, and dimensional stability of the material are not affected. This is the prerequisite for all modifications - the fundamental advantage of PPS cannot be sacrificed for damping.

(2) Introducing flexible energy dissipation micro zones

Introduce flexible micro regions with good compatibility with PPS into the matrix. These micro regions undergo reversible viscoelastic deformation when subjected to alternating stress, and the internal friction between molecular segments converts mechanical energy into thermal energy - this is the fundamental principle of viscoelastic damping.

(3) Build interface friction energy dissipation unit

Introduce a second component that combines moderately with the PPS matrix interface. Under vibration conditions, there is a slight relative displacement (internal friction) between the component and the matrix, which consumes additional vibration energy. This mechanism is similar to the microscopic version of the commonly used "friction damper" in engineering.

(4) Multi scale collaboration

The response frequency bands of flexible micro areas and interface friction units are different, and the energy dissipation mechanisms are complementary. The synergistic effect of the two can achieve a wider frequency band damping effect.

3.2 Typical Performance

After systematic formula optimization and process exploration, the typical properties of Wolf high damping PPS material (PPS+GF40) are as follows:

Regarding damping coefficient: A loss factor exceeding 0.20 means that the material can convert approximately 23% of vibration energy into thermal energy and dissipate it. As a reference, the value for conventional PPS is about 1% to 2%, with an increase of over an order of magnitude. By comparison, the damping value of steel is much lower than this, and the damping performance has a significant impact on NVH performance.

Regarding mechanical properties: While the damping coefficient has significantly increased, the tensile strength, elongation at break, and impact toughness have not decreased, and even slightly improved. The elongation at break exceeds 2.2%, which is better than the conventional 40% fiberglass reinforced PPS. This means that the material has more "fault tolerance space" when subjected to vibration, thermal expansion and contraction, or assembly stress. The bending modulus has decreased from 14 GPa to 11 GPa, which is still much higher than that of ordinary engineering plastics, and is still sufficient for thin-walled structural components such as junction boxes and electrical control housings.

Regarding heat resistance and insulation: The hot deformation temperature is maintained above 260 ° C, which is equivalent to conventional PPS and can withstand lead-free reflow soldering and automotive grade high temperature conditions. The volume resistivity is maintained at the level of 10 ¹⁵Ω· cm, meeting the insulation requirements of high-voltage electrical components.

　4、 Potential application areas

Based on the above material properties, the following applications may benefit from the introduction of high damping PPS:

4.1 Inverter/motor controller housing (combined with Wolfe EMC absorbing shielding material)

As the core power component of the electronic control system, the inverter has complex vibration sources, including internal excitation generated by high-speed switching of power devices, as well as external transmission from motors and road surfaces. The interior of the shell integrates a control board, a drive board, and various sensors, which require rigidity for vibration reduction. High damping shell materials can improve system vibration performance without adding additional components.

4.2 Automotive junction boxes and connectors

The junction box contains multiple terminal connection points inside, and long-term vibration may cause the terminals to loosen, increase contact resistance, and lead to local heating or even erosion. High damping PPS can absorb vibration energy from the material level, reduce the amplitude of vibration transmitted to the terminals, and improve long-term reliability.

The motor generates broadband vibration during operation, and sensors and actuators installed on or near the motor housing are subjected to this vibration for a long time. High damping materials help protect internal precision components, reduce signal jitter, and minimize the risk of contact transients.

4.4 Electrical components in other vibration environments

PPS components that work in vibration environments, such as compressor terminals, pump connectors, battery module end plates, etc., have potential application value.

V. Conclusion

The development of high damping PPS material is an exploratory attempt by Wolf Chemical in the field of functional PPS. Starting from the most basic material design, we have achieved a significant improvement in damping performance without sacrificing the inherent advantages of PPS - from the conventional 0.01~0.02 to 0.20-0.35, an increase of over an order of magnitude.