Why do we not recommend using the PCB which exceeds the shelf life?

Why do we not recommend using the PCB which exceeds the shelf life?

Due to the high risk of oxidation and components dropping

Each surface finish has a recommended assembly time and specific storage condition, boards that exceed the storage period will cause oxidation of the surface finish and also the high risk of dropping the components during the high temperature of assembly.

The recommended rework

According to the recommended storage conditions, the manufacturer cannot guarantee their quality if the PCBs have exceeded the storage time. Once the boards exceed the storage time, rework is recommended, such as baking before assembly or reapplying the surface finish, you can check our previous article for more information:
https://www.explus.com.tw/faq/why-does-long-stored-pcb-need-to-be-baked.html

However, not every material is suitable for rework, the binding force of PP between layers will decrease over time. When doing the rework process in the oven, one can run a high risk as those boards past their shelf life can cause delamination and blistering issues.

-