The automotive industry is currently undergoing a massive structural transformation, shifting from domain-based control systems to zonal E/E (Electrical/Electronic) architectures. This move is intended to reduce vehicle weight, streamline manufacturing, and facilitate the high-speed data transmission required for Software-Defined Vehicles (SDVs). As automakers consolidate control units based on physical zones rather than functions, the demand for highly reliable, space-efficient, and high-performance interconnects has never been greater.
In this context, the wiring harness—the “nervous system” of the vehicle—is facing its most significant evolution in decades. As we transition toward more complex high-voltage (HV) platforms, the integrity of every wire-to-terminal connection has become a critical safety parameter. Even in the era of autonomous driving, these metallurgical bonds remain the fundamental bridge between power sources and control units.
From the perspective of SBT Ultrasonic, ultrasonic welding technology is uniquely suited for joining large cross-section high-voltage cables to terminals. Compared to traditional welding methods, it offers distinct advantages, including lower internal resistance, minimal temperature rise, and superior ease of automation. As ultrasonic welding technology evolves, it enables safer, more efficient connections that are essential for the next generation of electric vehicles.
What is USCAR-38?
The USCAR-38 standard, developed by the United States Council for Automotive Research LLC (USCAR), defines the rigorous test methods and performance criteria for evaluating ultrasonically welded wire-to-terminal metallurgical bonds.
Key areas covered by the specification include:
Scope of Application: This standard applies to wires and terminals in road vehicle electrical connection systems. It is validated for ambient temperatures ranging from -40°C to +150°C and supports applied voltages from 0 to 60 VDC up to 1000 VAC/VDC.
Test Methods: USCAR-38 details essential testing requirements for ensuring bond quality, including visual inspection, cross-sectional analysis, and both tensile and peel strength tests.
Environmental Testing: To simulate the harsh realities of the road, the standard mandates environmental exposure testing, including thermal shock and temperature-humidity cycling. These tests verify the stability of the weld under extreme conditions, ensuring long-term durability.
According to the latest revisions of USCAR-38, an ideal ultrasonic weld must demonstrate specific characteristics, such as complete strand integration, proper nugget formation, and zero interference in functional zones.
Within the automotive electrical connection ecosystem, standards such as USCAR-38, USCAR-21, USCAR-37, and USCAR-45 form a comprehensive framework that underpins vehicle safety.
SBT’s Commitment to Reliability
SBT integrates the stringent requirements of USCAR-38 into the design and engineering of our Ultrasonic Wire Harness Welding Machines. Our equipment is built to handle diverse welding scenarios and is compatible with all mainstream wire cross-sections.
To move beyond traditional quality control, SBT has developed the Ultrasonic Welding Vibration Online Monitoring System. This technology addresses the limitations of conventional curve monitoring by providing comprehensive, real-time process analysis. It effectively prevents defects such as “cold welds” or joint failures, empowering production and quality teams to maintain high throughput without compromising safety. Additionally, our Lateral Force Monitor (WP) ensures real-time oversight of force changes, further guaranteeing the consistency of every weld.
[Image: SBT’s Ultrasonic Welding Vibration Online Monitoring System]
As a professional supplier of ultrasonic wire harness welding equipment, SBT Ultrasonic Technology Co., Ltd. is dedicated to providing the automotive industry with efficient, reliable, and internationally compliant welding solutions. We continue to drive innovation, helping our partners secure the future of automotive electrical safety.
（Please retain the images from our January/February issue’s WE, WS, WD, and WL Series, as shown above.）
See us in the USA!
Want to see these USCAR-38 compliant solutions in action? We’re bringing our latest technology to the Electrical Wire Processing Technology Expo, May 6-7, 2026 (Booth 1116). To book a private consultation during the expo, please contact Selina Wu at +86 15901603231 or [email protected].
Featured Tech: SBT Ultrasonic Wire Harness Welder WL
