Low temperature co sintered ceramic ribbon gold conductor paste, suitable for co firing with LTCC ribbon for platinum research, designed as an electrode for the inner or top layer

The multi chip module (MCM) of low-temperature co fired ceramic (LTCC) technology has the characteristics of high assembly density, light weight, and small volume, and is one of the effective methods to achieve high performance and miniaturization of electronic equipment. It has a wide range of application requirements in military electronics, aerospace, wireless communication and other fields. The key to restricting the application of LTCC technology in China is LTCC materials, including substrate materials, conductor pastes, and materials for embedded components. The conductor paste that matches the substrate has become one of the key materials that urgently needs to be solved. The paper focuses on the application requirements of military MCM, aiming to match the sintering of Ca-B-Si ribbonAu conductor pasteAs the research object, systematically study the influence of functional phase, glass phase, and organic carrier on the screen printing and matching co firing performance of conductor paste, and provide guidanceGold conductor pasteEngineering development.
The main work of the paper is as follows:
(1) The effects of organic carrier (molecular weight of thickener, thickener content, type and content of thixotropic agent), functional phase volume fraction (φ=13%, 20%, 46%), functional phase particle size (D50=0.9 μ m, 1.8 μ m, 3.1 μ m) and morphology on the rheological properties of the slurry were studied using a rheometer. The results indicate that increasing the molecular weight of the resin and the content of the thixotropic agent can improve the low shear viscosity of the slurry while maintaining a low high shear viscosity; As the solid volume fraction increases, the shear viscosity of the slurry also increases; When the solid phase volume fraction is 13%, the influence of functional phase particle size and morphology on the rheological properties of the slurry can be ignoredsilver conductive pasteSimulating the rheological properties of gold conductor paste, a gold conductor paste with a line resolution of about 80 μ m was obtained.
(2) The effects of functional phase particle size, bonding phase composition and content on the warpage deformation and microstructure of thick film conductor substrate interface after co firing of slurry and green tape were studied using surface profilometer, thermal mechanical analyzer, and scanning electron microscope. The results show that when the particle size of the functional phase is small, the thick film conductor becomes denser earlier, and there are more pores at the interface between the film layer and the substrate; When the particle size of the functional phase is large, the sintering of thick film conductors is not dense; When the particle size of the silver powder functional phase is 1.8 μ m, the co firing compatibility between the slurry and the green belt is optimal. The bonding phase with good fluidity under sintering process can promote the sintering density of thick film conductors, and reduce internal stress and regulate co firing warpage deformation by the movement of the bonding phase. However, thick film conductors become dense early, leaving a large number of pores at the interface between the thick film conductor and the substrate. The bonding phase with poor fluidity under sintering process will to some extent hinder the progress of solid-phase densification, providing more time for gas emission during substrate densification, but cannot adjust co firing warpage deformation according to its position changes.
(3) The influence of functional phase particle size, bonding phase composition and content on the microstructure and roughness of thick film conductor surface after co firing of slurry and green tape was studied. The results indicate that the particle size of functional phases has no significant effect on the distribution of bonding phases on the surface of thick film conductors, but as the particle size of functional phases decreases, the surface roughness of thick film conductors decreases. When using a bonding phase with good fluidity, the surface of the sintered thick film conductor is dense and there are many bonding phases present. The presence of blade shaped protrusions in the bonding phase will increase the surface roughness of the thick film conductor. As the content of bonding phase increases, the bonding phase on the surface of the thick film conductor increases after sintering.
(4) Based on the research results of silver conductor paste, the particle size of gold powder functional phase, organic carrier formula, bonding phase composition and content were optimized, and a co firing matching performance and wire bonding performance were preparedGold conductor paste.

Low temperature co fired ceramic substrate technology (LTCC) is a high-density integrated packaging technology, among whichGold conductor pasteIt is one of the key raw materials for preparing high reliability military electronic components, and its composition and properties have a great impact on the conductivity, welding performance, and co firing matching with the substrate of the sintered thick film This article mainly focuses on the preparation, sintering behavior, and co firing compatibility of functional phase micro sized gold powder in gold conductor paste with ceramic substrate ribbon. It is of great significance and application value for promoting the research and performance improvement of LTCC gold conductor paste Prepared by chemical reduction methodMicron sized gold powderExplored the influence of reaction conditions such as reducing agent type, dispersant type and dosage, pH value and temperature of the reaction system on the morphology and particle size of gold powder The results indicate that the crystal structure and symmetry of the reducing agent affect the morphology of gold powder. The particle size of gold powder decreases with the increase of dispersant dosage, reaction system pH, temperature, and reaction system addition rate The optimal preparation process for gold powder was determined. Under the conditions of a gold solution concentration of 20g/L, ascorbic acid concentration of 40g/L, dispersant dosage of 2:1, reaction pH value of 4, and reaction temperature of 50 ℃, spherical gold powder with an average particle size of 1.7 μ m and a particle size distribution of 0.8-5 μ m was prepared. The specific surface area was 0.184m2/g, the tap density was 4.76g/cm3, and the loose density was 7.46g/cm3, with good flowability The effects of gold powder particle size, glass powder softening point, and glass powder content on the sintering behavior of gold powder were studied. It was found that gold powder starts sintering between 300-400 ℃. The larger the gold powder particle size, the greater the degree of crystallization of the gold powder, and the lower the sintering activity, resulting in a higher starting temperature for sintering shrinkage of gold powder and a decrease in sintering shrinkage rate After adding glass powder, the higher the softening point of the glass powder, the higher the initial sintering shrinkage temperature of the gold powder Spherical gold powder with an average particle size of 1.7 μ m