The long-term reliability of PCBA depends on the comprehensive control of materials, structures and environmental adaptability during the design phase, and the following dimensions need to be focused on:
1. Substrate material performance:
High-frequency applications: 5G base stations and millimeter-wave radars need to use low dielectric constant (Dk < 3.5) boards (such as Rogers RO4000 series) to reduce signal transmission loss.
High-temperature scenarios: Automotive electronics require substrate Tg values > 170°C and metal substrates (such as aluminum-based and copper-based) with high thermal conductivity (> 1.5W/m·K) to prevent solder joint failure at high temperatures.
2. Solder joint reliability:
Although lead-free solder (such as SAC305) is environmentally friendly, its thermal fatigue life is 30% lower than that of tin-lead solder, and it is necessary to improve the alloy structure by adding elements such as bismuth (Bi) and antimony (Sb).
For vibration scenarios (such as industrial equipment), it is recommended to use Underfill to reinforce BGA packaging, which can increase the ability to resist mechanical shock by more than 5 times.
3. Environmental testing standards:
Temperature and humidity cycle: According to IPC-9701 standard, simulate extreme temperature changes from -40°C to 125°C to detect solder joint cracks.
Salt spray test: Coastal or vehicle-mounted PCBAs must pass a 96-hour neutral salt spray test (ASTM B117) to evaluate the corrosion resistance of the coating.
