The cause of bubbles in glass insulator

　　Glass insulator components are important parts of electronic components such as sealed relays, crystal components and connectors. The quality and performance of these components directly affect the quality of these electronic components. If the glass insulator defects, the sealing electrical properties, mechanical strength, etc. of these electronic components will therefore decline. Bubble is one of the main defects of the glass insulator. It not only affects the appearance of the glass insulator, but more importantly, it reduces the performance of the glass insulator and seriously impairs the product quality. With the electroplating, using and storing of glass insulator, bubbles will make descend range in electrical properties, mechanical strength and tightness of glass insulators get large significantly, which directly impacts the performance and reliability of electronic components.

　　Cause of bubbles:

　　According to the different locations of bubbles in the glass insulator, they an be divided into interface bubbles, internal bubbles and surface bubbles, with various shapes such as spherical, oval and trumpet; their chemical composition are also different, in addition to containing O2, N2, CO, CO2, SO2, but also contain nitrogen oxide and water vapor, etc., in which Nitrogen gas is generally dissolved in the glass in the state of physical solution, most of the other gases exist in a chemical bonding state. Their production is due to the gas does not completely and timely escape from the vitreous humour, but in the form of bubbles remain in the liquid, causes for these bubbles may be physical or chemical, to sum up mainly the following factors:

　　① Metal part itself contains carbon, sulfur, gas and other impurities, adsorbed moisture and pollutants, as well as adsorption of moisture on glass surface, in the sealing process they may cause a series of reactions, the formation of bubbles;

　　② When the ingredients are not expected to stir evenly and form small pieces, when binder in glass tube is not removed clearly, the formation of internal bubbles at high temperature sintering;

　　③ Sintering temperature is too high, the humidity in furnace is large, the gas released from decomposition of the glass itself and water vapor in the furnace dissolved in the liquid, to maintain the phase balance, and thus the gas cannot be vented thoroughly, resulting in internal bubbles;

　　④ In addition, graphite positioning module to absorb moisture or have pollutants, will lead to co-soluble with glass during high-temperature sintering to form surface bubbles.