Material Innovations in Insulated Bus Bar Support Screws for High-Voltage EV Platforms

Introduction

As new energy vehicles (NEVs) transition from 400V to 800V and even higher voltage architectures, electrical system design faces stricter demands on insulation reliability, thermal stability, and mechanical performance.

One critical yet often overlooked component in this system is the insulated bus bar support screw. These fastening components not only secure high-voltage busbars mechanically but also provide essential electrical isolation within battery packs, power distribution units (PDU), and inverters.

Material innovation has become the key driver in improving safety, durability, and lightweight performance in high-voltage EV platforms.

Why Material Selection Matters in High-Voltage EV Systems

In high-voltage EV environments, busbars carry large currents between battery modules, inverters, and charging systems. The support screws must withstand:

Continuous high voltage stress

High current thermal rise

Rapid temperature cycling

Strong vibration and mechanical shock

Strict creepage and clearance requirements

Automotive flame-retardant standards

Traditional metal screws alone cannot meet insulation requirements. Therefore, advanced insulated material solutions are now being widely adopted.

Evolution of Insulated Bus Bar Support Screw Materials

From Metal Fasteners to Hybrid Insulated Structures

Early EV systems relied on traditional metal screws combined with insulating sleeves or washers. However, this approach introduced risks such as:

Partial discharge at high voltage

Insulation aging

Reduced reliability under vibration

Modern designs increasingly use:

Fully insulated molded screw bodies

Overmolded metal cores with insulation coating

High-strength composite fasteners

These solutions improve system-level safety and reduce assembly complexity.

Key Material Innovations in Insulated Support Screws

High-Performance Thermosetting Composites (DMC / BMC)

DMC (Dough Molding Compound) and BMC (Bulk Molding Compound) materials are increasingly used in EV insulation support components due to:

High dielectric strength

Excellent arc resistance

Glass-fiber reinforced mechanical strength

Flame retardant capability (UL94 V-0 achievable)

Superior dimensional stability

These materials are ideal for high-voltage battery pack environments where both insulation and structural strength are critical.

High-Temperature Engineering Plastics

Advanced thermoplastics such as:

PPS (Polyphenylene Sulfide)

PEEK (Polyether Ether Ketone)

PA66 + GF (Glass Fiber Reinforced Nylon)

are used for lightweight insulated screw designs. These materials offer:

Continuous high temperature resistance

Chemical resistance to electrolytes

Strong vibration resistance

Reduced weight for EV lightweight strategy

In 800V platforms, high CTI (Comparative Tracking Index) materials are especially important to prevent electrical tracking.

Overmolding Technology

Overmolding combines a metal core for strength with an external insulation layer. This approach provides:

High torque capability

Stable clamping force

Reliable electrical isolation

Reduced risk of insulation displacement

It is widely adopted in power distribution units and inverter busbar fastening systems.

Performance Requirements in 800V EV Platforms

As EV systems move toward 800V architectures, insulated bus bar support screws must meet stricter criteria:

Higher Creepage and Clearance Distance

Material must support compact yet compliant insulation spacing.

Improved Thermal Resistance

Fasteners are exposed to heat generated by high current busbars and power electronics.

Stronger Vibration Resistance

EV battery packs are subject to continuous road vibration and mechanical shock.

Flame Retardant Performance

Automotive fire safety standards require V-0 flame-retardant materials.

Long-Term Aging Resistance

Materials must withstand thermal cycling, humidity, and electrical stress for over 10 years.

Material innovation directly influences these performance outcomes.

Lightweight and Integration Trends

Lightweight design remains a core goal in EV development. Advanced composite insulated screws:

Reduce overall system weight

Simplify assembly steps

Integrate mounting and insulation functions

Improve production efficiency

By replacing multi-component insulation structures with integrated insulated fasteners, manufacturers can reduce BOM cost and enhance reliability.

Future Development Directions

Looking ahead, material innovation in insulated bus bar support screws will focus on:

Higher CTI materials for ultra-high voltage platforms

Improved thermal conductivity with electrical insulation balance

Smart materials with condition monitoring capabilities

Eco-friendly and recyclable composite solutions

As EV platforms continue to evolve, fastening components will shift from simple structural parts to safety-critical engineered components.

Conclusion

In high-voltage EV platforms, insulated bus bar support screws are far more than mechanical fasteners. They are essential components ensuring:

Electrical isolation

Structural integrity

Thermal stability

Compliance with automotive safety standards

Material innovation — from thermosetting composites to high-performance engineering plastics and overmolding technologies — is enabling safer, lighter, and more reliable EV power systems.

As 800V and next-generation architectures become mainstream, advanced insulated fastening solutions will play an increasingly vital role in supporting the future of electric mobility.

FAQ

1. What is an insulated bus bar support screw in a new energy vehicle?

An insulated bus bar support screw is a fastening component designed to mechanically secure high-voltage busbars while providing electrical isolation. It prevents unintended electrical contact between conductive parts and grounded structures inside EV battery packs, power distribution units (PDU), and inverters.

2. Why are insulated support screws necessary in 800V EV platforms?

As EV systems move to 800V architectures, voltage stress increases significantly. Insulated screws help:

Prevent short circuits

Reduce the risk of electrical tracking

Maintain required creepage and clearance distances

Improve overall system safety

Higher voltage platforms demand materials with better dielectric strength and higher CTI performance.

3. What materials are commonly used for insulated bus bar support screws?

Common materials include:

DMC (Dough Molding Compound)

BMC (Bulk Molding Compound)

Glass fiber reinforced nylon (PA66 + GF)

PPS (Polyphenylene Sulfide)

PEEK (Polyether Ether Ketone)

These materials offer a combination of insulation performance, mechanical strength, thermal resistance, and flame retardancy suitable for automotive applications.

4. How do insulated screws improve EV safety?

Insulated screws reduce the risk of:

Electrical arcing

Insulation breakdown

Partial discharge

Thermal runaway caused by short circuits

By integrating insulation into the fastening structure, they enhance system-level electrical protection.

5. Can insulated bus bar support screws withstand high temperatures?

Yes. High-performance composite and engineering plastic materials are designed to withstand continuous elevated temperatures found in battery packs and inverters. Many materials can operate reliably above 120°C and maintain mechanical stability under thermal cycling.

6. Are insulated support screws suitable for vibration-prone environments?

Yes. EV battery systems experience constant vibration and mechanical shock. Glass fiber reinforced composites and overmolded structures provide high mechanical strength and crack resistance, ensuring long-term durability.

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