Improvement on Conductivity for Thick Film Aluminum Paste

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Silver and copper pastes are current electric conductive fillings.
• Silver is costly, and copper requires a reducing atmosphere for sintering.
• Aluminum offers a low-cost, air-sinterable alternative with good electrical conductivity.

Purpose of the Study:

• To develop a high-performance aluminum paste for electric conductive fillings.
• To investigate the effects of particle size, glass frit, and solid content on aluminum paste conductivity.
• To achieve low sheet resistance through optimized formulation and sintering.

Main Methods:

• Utilizing aluminum powder with mixed large and small particle sizes to leverage fracture and gap-filling mechanisms.
• Employing liquid phase sintering and controlling the oxidation layer fracture mechanism.
• Investigating the effect of glass frit content for particle bonding and oxidation inhibition.
• Optimizing solid content for high electrical conductivity.

Main Results:

• Formulated aluminum paste achieved a sheet resistance of 4.5 mΩ/□ after sintering at 850 °C for 10 min.
• Optimal formulation involved a 4:1 ratio of large to small aluminum particles, 10 wt% glass frit, and 80 wt% solid content.
• Glass frit effectively bonded aluminum particles and inhibited oxidation, contributing to improved conductivity.

Conclusions:

• Aluminum paste is a viable, cost-effective alternative to silver and copper for electric conductive fillings.
• Optimized aluminum paste formulation enables high electrical conductivity suitable for various applications.
• The developed method demonstrates a pathway to achieving superior performance in air-sinterable conductive pastes.