Impact Of Hot-Cutting Defect On Reliability Of Ceramic Packaging And A Novel Concept Of Structure Design

Ceramic packaging is widely utilized for high reliable and hermetical packaging, however, the ceramic packaging manufacturing in China still has the problem of a low product yield. Based on researching the defect generated in the ceramic forming, optimization design of package structure is developed to improve the product yield and the reliability of packages.The defect forming in hot-cutting process is described in this paper. The Weibull strength distribution for brittle materials is introduced to estimate how the defect impacts the ceramic component. By contrast with the natural specimen, the specimens with hot-cutting defect have a remarkable decline in strength for their much bigger defect size.For specimens with natural surface, research on the size effect of strength reveals that when the effective volume approaches or less than the size of the defect, the size effect of strength disappear for the experimental strength data deviates a lot from the theoretical Weibull function. For specimens with hot-cutting defect, the deviation gets much more pronounced for two reasons: one is the loss of the effective surface concept utilized in Weibull function, the other is the density of the defect gets so high to resulting in an interaction between defect, which deviates form the weakest-link theory. The interlinking of the defects makes defect size get bigger than its original size, which is the reason strength of specimens with hot-cutting defect decrease much more. The mechanism of forming of the hot-cutting defect is the change in shape and scale of cut-tool tip. The wear between the cut-tool tip and the alumina particles leads to the change.A novel method is developed to improve the integrality of the cutting surface to improve the strength. The film of tungsten-metallization on the cutting surface can mend the defect on one hand, on the other hand, it can generate press internal-stress in ceramic, both can improve strength. But the ascending R-curve resulting from the metallization improves the strength and reduces the scatter of the strength essentially.To investigate how the package structure impact the stress in the ceramic in ceramic manufacturing and service condition, a FEM method(ANSYS software) is adopted to quantitatively investigate how the shape of the ceramic case can change the stress distribution in the ceramic case. Based on the stress analysis, a structure design concept called Defect-Free-Stress is put forward considering the failure caused by the interaction between the defect and the stress. Considering the hot-cutting defect and the stress induced by the brazing process of ceramic insulator with metal case and sink. The design concept is applied to obtain the scale design standard and the material selection standard in of the brazing process.