Abstract
Silver paste is widely used for low-temperature co-fired ceramic (LTCC) electrodes. In this work, a kind of LTCC silver paste for fine-line screen-printing was developed by considering the effect of the organic vehicle on rheological behavior and screen-printing properties. A step-by-step volatilization mode was applied to screen the mixed organic solvent of α-terpineol, 2-(2-butoxyethoxy) ethyl acetate (BCA) and dibutyl phthalate (DBP). The α-terpineol:BCA:DBP ratio of 5:2:3 is selected by considering the volatility, viscosity, and pseudoplasticity of the organic vehicle. Both viscosity and pseudoplasticity of shear-thinning increase with the increase of ethyl cellulose (EC) organic binder content. Three interval thixotropy test (3ITT) was conducted to discuss the thixotropy of silver paste. The minimum printing line width of 13.27 µm is obtained using silver paste with 10 wt% EC, confirming that the homemade paste has good printability.
Highlights
Low-temperature co-fired ceramic (LTCC) technology is considered to be an important approach for high-frequency applications due to the advantages in compact packaging and good signal transmission for 5G/6G mobile communication systems [1–3]
It is necessary to ensure the viscosity and pseudoplasticity of an organic vehicle to adjust the rheological properties of paste and realize high-resolution printing
This section studies the effects of mixed solvents on volatility, viscosity, and pseudoplasticity of organic vehicle
Summary
Low-temperature co-fired ceramic (LTCC) technology is considered to be an important approach for high-frequency applications due to the advantages in compact packaging and good signal transmission for 5G/6G mobile communication systems [1–3]. The most commonly used solvents in an organic vehicle are ester alcohols and terpenes, such as terpineol or their mixtures with other solvents, and the slight change of solvent content will have a great influence on the rheological properties of silver paste [19] Various combinations of these solvents are needed to obtain the required volatility. It is very necessary to systematically study the effects of an organic vehicle, especially the solvent composition and EC content in the mixed solvent, on the rheological behavior and fine-line screen-printing characteristics of silver paste. A kind of LTCC silver paste for fine-line screen-printing was developed by optimizing the composition of an organic vehicle, including solvent and binder. Optical microscope (Leica, DM 2500M, Wetzlar, Germany) and Scanning Electron Microscope (Phenom Pro, Phenom-world, Eindhoven, The Netherlands) were used to observe and measure the widths and micro morphologies of screen-printed lines
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