Formation of diffusion barrier layers for thermoelectric modules via electroless Ni-P plating

Area of Science:

• Materials Science
• Surface Engineering
• Thermoelectrics

Background:

• Thermoelectric elements require robust diffusion barrier layers to prevent degradation.
• Intermetallic compound formation between solders and thermoelectric materials can compromise device performance.
• Selective plating techniques are crucial for efficient fabrication of electronic components.

Purpose of the Study:

• To develop and evaluate electroless Ni-P plating as a diffusion barrier for thermoelectric elements.
• To investigate the use of surface activation and sodium dodecyl sulfate for selective Ni-P plating.
• To assess the effectiveness of the Ni-P layer in preventing interdiffusion and intermetallic compound formation.

Main Methods:

• Electroless Ni-P plating with sensitization and activation pre-treatments.
• Surface wettability control using sodium dodecyl sulfate (anionic surfactant).
• Contact angle measurements and X-ray photoelectron spectroscopy (XPS) for surface analysis.
• Electron probe microanalysis (EPMA) for microstructural and interfacial characterization.

Main Results:

• Achieved uniform and selective Ni-P plating through controlled surface activation and wettability.
• The Ni-P layer effectively suppressed the formation of intermetallic compounds between solder and thermoelectric elements.
• EPMA confirmed that the Ni-P layer prevented copper diffusion into thermoelectric elements, even after thermal treatment.

Conclusions:

• Electroless Ni-P plating serves as an effective diffusion barrier for thermoelectric applications.
• Surface activation and surfactant-controlled wettability enable selective plating for improved fabrication.
• The developed method enhances the reliability and longevity of thermoelectric modules by preventing material degradation.