Precision Spring Contacts for German Automotive Sensor: Ensuring Long-Term Reliability

The German automotive industry sets the global standard for reliability and durability. Electronic components must perform consistently over years of operation under extreme conditions—temperature fluctuations from -40°C to +125°C, continuous vibration, and exposure to contaminants. For automotive electronics suppliers, selecting a stamping partner with proven quality systems, full traceability, and long-term reliability is essential for meeting Tier 1 and OEM requirements.

Client: AutoSense GmbH, a German automotive supplier based in Stuttgart, providing sensor systems for electric vehicle battery management and thermal monitoring.

Specific Product: Precision Spring Contact Terminal—a stamped component within the temperature sensor assembly, ensuring reliable signal transmission between the sensor element and the control unit.

• Long-Term Reliability: The terminal needed to maintain stable contact resistance and spring force over 15 years of service life and 5,000+ mating cycles, under continuous vibration.
• Temperature Stability: Performance had to remain consistent across the full automotive temperature range (-40°C to +125°C).
• Material: Copper alloy C7025 specified for its combination of conductivity, strength, and stress relaxation resistance at elevated temperatures.
• Strict Tolerances: Critical dimensions required ±0.015mm accuracy to ensure proper mating force and electrical performance.
• Plating: Selective gold plating on contact areas with nickel underplate, requiring precise thickness control and adhesion.
• Documentation: Full PPAP documentation required, including material certifications, process capability studies, and dimensional reports.
• Volume: Initial annual volume of 80,000 pieces with quarterly deliveries.

Tingfeng Hardware's engineering team approached this with a focus on process capability, long-term stability, and full documentation.

Our engineers conducted a thorough DFM analysis, optimizing the part geometry for progressive die stamping while preserving functional requirements. We developed a detailed process flow including in-die contact resistance monitoring and planned capability studies for all critical dimensions.

The progressive die was designed with precision-ground tool steel and implemented in-die sensors for real-time process monitoring. After tool completion, we conducted a full capability study on 300 consecutive parts, demonstrating:

• Cpk >1.67 on all critical dimensions including contact height and bend angles
• Spring force variation within ±3% across the sample
• Burr height consistently below 0.015mm

We submitted complete PPAP documentation including control plans, process flow diagrams, FMEA, and dimensional reports. Production commenced with:

• 100% optical inspection of critical features
• Statistical sampling for contact resistance and spring force
• Real-time SPC monitoring throughout the run

For quarterly deliveries, we maintain the same rigorous inspection protocols. Each shipment includes material certifications, dimensional reports, and test results.

• Achieved Cpk >1.67 on all critical dimensions
• Maintained contact resistance within specification across all production batches
• Completed PPAP approval within 5 weeks
• Delivered first production batch of 20,000 pieces on schedule
• Achieved zero defects across all delivered batches to date

This case demonstrates Tingfeng Hardware's readiness for the demanding German automotive market. With IATF 16949 certification, comprehensive quality systems, proven process capability, and full documentation, we deliver the reliability that automotive suppliers require.

For European automotive manufacturers seeking a stamping partner who understands their quality expectations and long-term reliability requirements, Tingfeng Hardware offers a proven, collaborative solution.