PCB baking conditions
Typical industry settings for PCB baking conditions and time are as follows:
1. For PCBs within 2 months of manufacture, well sealed, then left more than 5 days after opening in a controlled environment (≤30℃/60%RH per IPC-1601): bake at 120±5℃ for 1 hour before production.
2. PCB stored 2-6 months past manufacture: bake at 120±5℃ for 2 hours before production.
3. PCB stored 6-12 months past manufacture: bake at 120±5℃ for 4 hours before production.
4. PCB stored more than 12 months past manufacture are generally not recommended: multilayer bond strength ages over time and may cause unstable function and higher field returns, plus risks of board explosion and poor wetting in production. If they must be used, bake first at 120±5℃.
Another reason not to use long-stored PCBs is that surface finishes age. For ENIG the industry shelf life is typically 12 months; beyond that, if the immersion-gold layer is thin, nickel may diffuse through the gold and oxidise, hurting reliability.
5. All baked PCBs must be used within 5 days; unfinished boards must be re-baked at 120±5℃ for 1 hour before production.
