Why PCB Baking Before Reflow Is Essential

PCBs must undergo baking before entering the reflow furnace to prevent moisture-related issues. Moisture can lead to vapor formation within the PCB, causing risks like popping or delamination even after production.

Effects of Moisture in PCBs

When exposed to high temperatures exceeding 100℃ in furnaces, water inside PCBs turns into vapor, rapidly expanding. This expansion can lead to PCB bulging, especially in the Z direction, risking broken VIAs or layer separation, resulting in blistering, expansion, or plate bursting.

Preventing Internal Damage

Internal damage from moisture can cause electrical instability, CAF, and other issues, ultimately leading to product failure. PCB baking involves removing the original package and maintaining a temperature over 100℃ to prevent excessive vapor expansion that could rupture the PCB.

Proper PCB Baking Process

The industry standard for PCB baking includes setting a temperature of 120±5℃ to ensure effective moisture elimination before SMT line plate welding. Baking time varies based on PCB thickness and size, with specific guidelines for different storage durations.

Storage and Usage Recommendations

Stored PCBs should be baked before extensive production to prevent surface treatment failure, particularly in ENIG. It is recommended to use baked PCBs within five days and untreated PCBs should undergo another baking session before use.

Best Practices for PCB Baking

During PCB baking, flat stacking is advisable to prevent bending, with specific limits on the number of pieces per stack based on size. After baking, it’s crucial to let the PCB cool down before further handling.