# Physical Properties of Paste Synthesized from Wet- and Dry-Processed Silver Powders

## TL;DR

This paper compares silver pastes made from wet and dry processing methods, focusing on their physical properties and performance after low-temperature curing.

## Contribution

The study introduces a comparison of physical and electrical properties of pastes made from wet- and dry-processed silver powders for low-temperature applications.

## Key findings

- Wet-processed pastes are plastic fluids, while dry-processed pastes behave more like pseudoplastic fluids.
- Dry-processed pastes show significantly better conductivity after low-temperature curing.
- Wet-processed pastes remain nonconductive after curing at 130 °C for 30 minutes.

## Abstract

This study compares the characteristics and low-temperature curing properties of pastes prepared from silver (Ag) powders synthesized by either wet powder (WP) or dry powder (DP) processing. The WP synthesis of electrode particles has the advantage of controlling the average particle size and particle size distribution but the disadvantage of producing low-purity, crystalline particles because they are synthesized through chemical reduction at less than 100 °C. Conversely, the DP synthesis of electrode particles has the advantage of producing pure, highly crystalline particles (due to synthesis at high temperatures) but the disadvantage of a high processing cost. WP and DP were used to manufacture pastes for low-temperature curing, and the physical properties of the pastes and the electrode characteristics after low-temperature curing were compared between powder types. Shear stress as a function of the shear rate shows that the WP paste is a plastic fluid, whereas the DP paste is a pseudoplastic fluid, closer to a Newtonian fluid. Screen printing the Ag pastes and curing for 30 min at 130 °C produces a nonconductive WP paste, whereas it produces a DP paste with a conductivity of 61 mΩ/sq, indicating that the highly crystalline DP paste is advantageous for low-temperature curing.