PA66 Nylon Screws in Automotive ECU - Replace Metal, Reduce Weight | FASTKING Case
Case Background
A tier-1 automotive electronics supplier was developing a new-generation ECU (engine/body control unit) and originally used SUS304 stainless steel Phillips countersunk screws to fasten the PCB and housing. Two issues emerged during validation:
- Metal screws could wear the PCB pads under long-term vibration, causing intermittent shorts with a 0.3% failure rate.
- Each stainless screw weighed 1.8g; with 24 screws per board, total screw weight was 43g, conflicting with vehicle lightweighting targets.
Solution
FASTKING engineering recommended pa66 + 30% glass fiber (GF30) nylon screws to replace stainless steel. Glass fiber reinforcement raises the tensile strength of pa66 from 60 MPa to 170 MPa and the heat deflection temperature from 75°C to 250°C, suiting the ECU operating environment.
Specifications
- Material: PA66 + 30% glass fiber (black, UL94 V-2)
- Sizes: M3×8 / M4×10 / M5×12 Phillips countersunk + M4 hex socket nut
- Assembly torque: 0.6-0.8 N·m (GF30 resists thread stripping)
- Certifications: RoHS, REACH, IATF 16949 (automotive quality)
Results
Over 12 months, FASTKING delivered 380,000 PA66 screws for this program:
- Weight per screw reduced from 1.8g to 0.7g, saving 26g per board (~60%).
- Short-circuit failures eliminated; PCB pad wear issue fully resolved.
- Insulation resistance 10^14 Ω, far exceeding metal screws.
- Now adopted on the customer's VCU and BCM platforms, delivering an 18% annual cost reduction.
Contact the FASTKING engineering team for automotive-grade fastener selection or samples.