What is the reason why black spots and pores appear after drying and sintering of screen-printed electrode pastes?

The reasons for the occurrence of black spots and pores during the drying and sintering of screen-printed electrode pastes may involve multiple factors, including slurry, process and equipment.

Here are some common causes that can cause these problems:

1. Electrode slurry: It may be due to problems with the components or quality of the electrode slurry itself, such as impurities, uneven solid particles, unstable volatile components, etc., which leads to adverse phenomena during drying and sintering.

2. The process parameters are inappropriate:

(1) The drying temperature is too high or too low: When drying, if the temperature is set too high, it may cause the slurry to volatilize rapidly and form bubbles or pores; otherwise, if the temperature is too low, it may cause incomplete drying and cause black spots to occur in the residue.

(2) Insufficient sintering temperature and time: During the sintering process, if the temperature is not high enough or the time is not long enough, the organic substances in the electrode slurry may not be completely burned out, forming residues or pores; at the same time, if the temperature is too high or the time is too long, it may lead to uneven sintering or burning of the electrode material, resulting in black spots.

3. Equipment issues:

(1) If the drying equipment is poorly ventilated or the temperature distribution is uneven, it may cause local overheating or overdrying of the slurry, causing residues or pores.

(2) Sintering equipment: The temperature control of the sintering equipment or the poor sealing of the crucible may lead to unstable sintering temperature and atmosphere, resulting in poor sintering.

4. Environmental factors: Dust, pollutants, etc. in the production environment may adhere to the surface of the electrode slurry or the substrate during the sintering process, affecting the sintering quality and forming black spots.