Deposition of High Conductivity Low Silver Content Materials by Screen Printing

Jewell, Eifion; Hamblyn, Simon; Claypole, Tim; Gethin, D. T.

doi:10.3390/coatings5020172

Cited by 18 publications

(15 citation statements)

References 12 publications

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“…This could cause print defects such as agglomerations or mesh marking, where there are significantly raised areas in the print profile which correspond with the frequency of the mesh used that in severe cases are surrounded by areas of little or no ink deposit. Mesh marking has been observed in other studies with highly viscous and elastic inks, where it has had a significant impact of the electrical performance of the print [10,[37][38][39]. The elasticity of the ink can depend on several factors including the particle morphologies, interactions between particles, particle size distribution as well as solvents and resins used.…”

Section: Discussionmentioning

confidence: 95%

The Effect of Carbon Ink Rheology on Ink Separation Mechanisms in Screen-Printing

et al. 2020

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Screen-printable carbon-based inks are available in a range of carbon morphologies and concentrations, resulting in various rheological profiles. There are challenges in obtaining a good print when high loading and elasticity functional inks are used, with a trade-off often required between functionality and printability. There is a limited understanding of how ink rheology influences the ink deposition mechanism during screen-printing, which then affects the print topography and therefore electrical performance. High speed imaging was used with a screen-printing simulation apparatus to investigate the effect of viscosity of a graphite and carbon-black ink at various levels of solvent dilution on the deposition mechanisms occurring during screen-printing. With little dilution, the greater relative volume of carbon in the ink resulted in a greater tendency towards elastic behavior than at higher dilutions. During the screen-printing process this led to the ink splitting into filaments while remaining in contact with both the mesh and substrate simultaneously over a greater horizonal length. The location of separating filaments corresponded with localized film thickness increases in the print, which led to a higher surface roughness (Sz). This method could be used to make appropriate adjustments to ink rheology to overcome print defects related to poor ink separation.

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Section: Discussionmentioning

confidence: 95%

The Effect of Carbon Ink Rheology on Ink Separation Mechanisms in Screen-Printing

et al. 2020

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“…1,8,9 The effect of mesh material and geometry was found to be relatively consistent for a range of inks, with finer meshes leading to reduced film thickness but improved definition, which is preferable for fine feature printing. [9][10][11] Parameters such as squeegee hardness, angle, and geometry have also been found to have consistent effects on a range of inks, where softer squeegees at shallow angles were found to produce thicker deposits. 12 However, squeegee pressure, snap-off distance (the distance between the screen and the substrate) and print speed have not demonstrated consistent trends and have been shown to vary with the rheology of the ink.…”

Section: Introductionmentioning

confidence: 88%

High-speed imaging the effect of snap-off distance and squeegee speed on the ink transfer mechanism of screen-printed carbon pastes

et al. 2019

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Screen printing is the most widely used process in the production of printed electronics due to its ability to consistently transfer inks containing a wide range of functional materials onto a range of substrates. However, despite its extensive use, the mechanism by which the ink is transferred through the mesh and onto the substrate is not fully understood. Existing theories are contradictory and lack experimental validation. Therefore, high-speed imaging was used in combination with a screen-printing simulation rig that was designed to provide good optical access to study ink deposition during the screen-printing process. The variation in the four stages of ink flow through the screen, described in the theory by Messerschmitt, has been quantified with respect to changes in snap-off distance and squeegee speed. Analyses of the images were compared with measurements of the ink properties and corroborated with analyses of the prints. This has provided a better understanding of the mechanism by which the ink transfers from the mesh to the substrate and subsequently separates in screen printing. This could be used as the basis for the development of predictive algorithms, as well as to improve the understanding of how to optimize print quality and performance.

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“…State-of-the-art screens are usually made with an angle of φ = 22.5 . [16][17][18] Because of this choice, wire crossings always exist within each screen opening, limiting the printability and reducing the local finger height, respectively. In recent years, so-called "knotless screens" emerged, where the mesh is aligned at a 0 angle, avoiding any wire crossings within the screen opening, thus increasing the potential paste transfer.…”

Section: Introductionmentioning

confidence: 99%

Screen pattern simulation for an improved front‐side Ag‐electrode metallization of Si‐solar cells

Tepner

Ney

Linse

et al. 2020

Progress in Photovoltaics

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Flatbed screen printing proves to be the dominant metallization approach for mass production of silicon (Si)‐solar cells because of its robust and cost‐effective production capability. However, the ongoing demand of the PV industry to further decrease the width of printed Ag‐electrodes (contact fingers) requires new optimizations. This study presents the latest results on Si‐solar cell metallization using fine‐line screens down to screen opening widths of wn = 15 μm. The best experimental group achieved a record finger geometry with a mean finger width of wf = 19 μm and a mean finger height of hf = 18 μm. Furthermore, solar cell performance using a front‐side grid with a screen opening width of wn = 24 μm is investigated, reporting cell efficiencies up to 22.1% for Passivated Emitter and Rear Contact (PERC) solar cells. Finally, a novel screen pattern simulation is presented, revealing a correlation between the measured lateral finger resistance and the novel dimensionless parameter screen utility index (SUI). It describes the ratio between the average size of individual openings defined by the screen mesh angle and the chosen underlying mesh type. For SUI < 1, the printing result will strongly depend on the screen configuration, whereas for values of SUI > 1, the impact of the screen on the overall printability diminishes.

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Deposition of High Conductivity Low Silver Content Materials by Screen Printing

Cited by 18 publications

References 12 publications

The Effect of Carbon Ink Rheology on Ink Separation Mechanisms in Screen-Printing

The Effect of Carbon Ink Rheology on Ink Separation Mechanisms in Screen-Printing

High-speed imaging the effect of snap-off distance and squeegee speed on the ink transfer mechanism of screen-printed carbon pastes

Screen pattern simulation for an improved front‐side Ag‐electrode metallization of Si‐solar cells

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