Application of Borate Glasses in Electronics
Glasses are widely used in the electronics industry. Such applications as sealing to form hermetic packages, bonding ferrites to form storage heads, depositing coatings on silicon for passivation, forming dielectrics for high speed transmission of signals, and fabrication of displays which may require as many as six different glasses, all require glasses with significant amounts of B2O3 in their composition. While B2O3, by itself, does not have much application, primarily because of its poor chemical durability, glasses containing B2O3 content in the range of 5 to 40% do offer technological properties, one application that takes advantage of the low-melting properties of B2O3 is in a plasma display panel; a schematic of which is shown in Fig. 1. This display which consists of as many as six different glasses to fabricate the assembly, requires approximately 1 mil thick bubble-free coating of a dielectric glass on commercial soda-lime-silica substrates. Since typical soda-lime-silica substrates of any significant size cannot withstand processing temperatures in excess of about 600°C, dielectric glasses with very steep viscosity as a function of temperature had to be developed. Since the sealing of the panel is done to dielectric surfaces, it meant that further low-melting yet thermal expansion matching the dielectric had to be developed. Both these glasses were developed in the lead borate system with modifications to obtain steep viscosity for the dielectric and low-softening and flow out temperatures for the seal.
KeywordsDeformation Temperature Borate Glass Seal Glass Plasma Display Panel B203 System
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