Improvement Of Resistance To Cracking Of Glass Sealed With Steel

Glass-metal sealing Technology is widely used in electronic metal components. Besides, metal always use Kovar alloy which has low expansion coefficient while glass always use borosilicate glass. But Kovar alloy has many shortages, just as lower conductivity for heat, lower corrosion resistance and higher price. So, it is expected that cheaper low carbon steel, ex. 10#steel, may in place of Kovar in components which demands well performance in rejection of heat, just as large power devices and relays. The glass which is sealed with steel belongs to iron sealing glass. The DG-502 glass which was made indigenous belongs to it. But DG-502 do harm to environment because of having 30wt% of PbO. Recently, the ST-4CK glass which was made by NEG, began to be used by Metal component research institutes and companies in China. As a kind of non-crystalline glass, it still couldn't avoid dehiscence when the leading wire came across stresses. In order to improve the reliability of components, a lot of exploratory works have been down on development of more reliable glass which used to seal with steel in this thesis.The first part is preparation research. First, the oxidization of 10# steel was researched under controlled atmosphere. Pure Fe₃O₄ oxide film gained in N2-2.31%H2O-0.95%H2 atmosphere in 550℃for 30 minutes. However, when the ST-4CK glass was sealed with 10# steel, the insulation resistance was more than 1×10⁹Ω, and the leakage rate reached 10-9Pa·m3/s。However, the glass broke when the lead was bended only once. Main compositon of ST-4CK glass was determined by EMS and XRF analysis. Helped by software, we made a glass which was simulated with the ST-4CK glass. It can be sealed with 10#steel well.In the second part, researches on two paths were made by means of strengthening in order to improve the reliability of the products in electronic package. First, Al2O3 particle oxide(10wt%,15wt%,20wt%,25wt%) were added into the ST-4CK glass to do experiments. Glass which were added 15wt% Al2O3 particle oxide was sealed well with 10# steel. The insulation resistance of it was more than 1×109Ω, and the leakage rate reached 10-⁹Pa·m³/s。Especially, the glass didn't break when the leading wire was bended for 90 degrees thrice. When the leading wire was bended for 90 degrees for the fifth time, a little split appeared between the glass and the wire while the glass remained unbroken. Second, on the bases of ST-4CK glass, researches on regulating the glass composition were done to realize crystallization to improve the intensity of the glass. By research, a new SiO₂-BaO-K₂O-Na₂O-Al₂O₃-ZnO-CaO glass-ceramic which can separate out K₂Ba₇Si₆O₄₀ crystal and BaSi2O5 crystal was made. As the mechanics of K₂Ba₇Si₆O₄₀ crystal belongs to surface crystallization, it wouldn't appear in sealing experiment for the glass was kibbled. The glass-ceramic did well performance in the sealing experiment. The result showed that the glass has a insulation resistance of more than 1×10¹⁰Ω, and the leakage rate reached 10^-9Pa·m³/s。Especially, the glass didn't break when the leading wire was bended for 90 degrees thrice. When the leading wire was bended for 90 degrees for the fifth time, a little split appeared between the glass and the wire while the glass remained unbroken. The glass-ceramic has a simple technology of production like ST-4CK glass, which doesn't need heat treating on nucleation temperature and crystallization temperature.