Daniel Lacorte | Ames Goldsmith: What are the key conductivity mechanisms in submicron silver flakes, and how do they differ between fired and non-fired applications?

Sintering vs. simple contact: Can two completely different conductivity mechanisms achieve the same high performance?

This clip compares two distinct silver flake materials in an epoxy formulation: a fine, one-micron flake with high surface energy (SF210) and a large, nine-micron high-aspect-ratio flake (SF175). Both are cured under identical conditions (200°C for 30 minutes), raising the question of how these morphologically different particles establish a conductive network and if their performance will differ.

Using cross-section SEM images, the analysis reveals two different physical phenomena at play. The smaller, high-energy SF210 flakes exhibit clear signs of sintering, with pronounced "necking" between particles forming a fused, monolithic network. This process is driven by the material's inherent tendency to reduce its high surface energy at elevated temperatures, causing atomic diffusion and fusion at the contact points.

In contrast, the larger SF175 flakes show no evidence of sintering. Instead, conductivity is achieved purely through inter-particle contact, where the large, flat flakes are pressed against each other during the resin's curing and shrinkage. Despite these fundamentally different mechanisms, both materials surprisingly achieve the same low volume resistivity, demonstrating the versatility in material design to meet performance targets.

In this short video, you can learn:
* The visual difference between a sintered and a non-sintered conductive network.
* How particle size and surface energy drive the sintering process in conductive pastes.
* That high conductivity can be achieved through either particle fusion (sintering) or simple flake-to-flake contact.

📋 **Clip Abstract** This clip uses powerful SEM imagery to compare two silver flakes that achieve high conductivity through entirely different mechanisms: sintering and inter-particle contact. It demonstrates that material selection allows for tailoring the physical process to meet specific application needs without compromising electrical performance.
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Can you get better performance for less cost? Why silver-coated copper might be the future for some printed electronics.

Addressing the major industry challenge of rising silver prices, this clip introduces silver-coated copper particles as a high-performance, cost-effective alternative. The core concept is to leverage an inexpensive copper core while using a thin, functional layer of silver on the surface to provide oxidation resistance and excellent conductivity. The manufacturing process involves an electroless plating of silver onto the copper, which can then be mechanically milled into flakes to enhance particle-to-particle contact.

The speaker presents compelling comparative data between a pure silver flake and a silver-coated copper flake with a similar particle size (D50). Both materials were formulated into pastes at the same weight percent, achieving similar viscosities. This sets the stage for a direct, apples-to-apples comparison of their electrical performance in a realistic formulation.

The results are striking: the silver-coated copper flake, containing only 15% silver by weight, not only matches but slightly outperforms the pure silver flake in terms of electrical conductivity. This demonstrates that it's possible to significantly reduce the precious metal content and cost of a formulation without sacrificing, and in some cases even improving, performance. The speaker notes this technology is already gaining traction in demanding applications like HJT photovoltaics.

In this short video, you can learn:
* The structure and manufacturing process of silver-coated copper particles.
* How silver-coated copper can significantly reduce material costs in conductive inks.
* Performance data showing that silver-coated copper can match or exceed the conductivity of pure silver.

📋 **Clip Abstract** This clip presents a compelling case for silver-coated copper as a cost-effective alternative to pure silver in printed electronics. It explains the material's structure and presents data showing it can deliver superior electrical performance at a fraction of the cost, addressing a key market need.
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How can a simple surface coating on a silver particle be the key to unlocking low-temperature sintering?

This segment delves into the critical role of surface chemistry in enabling low-temperature sintering for printed electronics. The speaker explains that the organic surfactants or coatings on silver particles are non-conductive and must be removed for sintering to begin. Differential Scanning Calorimetry (DSC) is introduced as a key analytical tool to understand the decomposition temperature of these coatings, which is the first step in designing a low-temperature system.

The DSC data clearly shows that different coatings (NM2, W, and NM3) on the same one-micron silver platelets have distinct decomposition profiles. By selecting a surfactant with a lower boiling point, like the NM3 coating, the silver surface becomes exposed and available for sintering at a much lower temperature. This is a crucial capability for processing on heat-sensitive flexible substrates like PET or PEN.

The analysis is powerfully reinforced with SEM images of the three materials after a low-temperature cure at 170°C. The coating with the highest decomposition temperature (NM2) shows no sintering and no conductivity. In contrast, the NM3 coating, which decomposes earliest, facilitates extensive inter-particle necking and a dense silver network, resulting in an orders-of-magnitude improvement in resistivity.

In this short video, you can learn:
* Why organic coatings on silver particles must be removed to initiate sintering.
* How to use DSC analysis to select the right surface chemistry for low-temperature applications.
* The direct visual correlation between surfactant decomposition, particle necking (sintering), and conductivity.

📋 **Clip Abstract** This clip reveals how tailoring the surface chemistry of silver particles is essential for achieving low-temperature sintering. It expertly links analytical DSC data on surfactant decomposition to SEM evidence of particle fusion and the resulting dramatic improvements in electrical conductivity.
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