EP-0463826-A1: Sealing Glass and Electrically Conductive Formulation

This patent describes a glass sealing process that bonds semiconductor chips ("dies") to ceramic substrates, by firing at temperatures of less than 400 C. The sealing glass is composed primarily of an electrically conductive Silver paste, which can efficiently bond silicon semi-conductive devices to ceramic. Several trials were conducted to assess the strength of the paste's ceramic bonding, by heating a series of samples to different maximum temperatures that ranged from 300 to 420 C. Furthermore, these samples were heated to temperature at the uniform rate of 10 C per minute, and were held at maximum temperature for between 10 and 15 minutes. Results showed that while the strength of the bond was superior at a higher temperature, adequate bond strength was achieved at temperatures less than 400 C. A second experiment that follows the above process was conducted, except the composition was prepared and melted in a belt furnace at 900 C. for ~90 minutes. Results continued to show that a higher temperature increased the bond strength, and that sufficient bond strength was achieved at less than 400 C. This ultimately allows for the manufacturing of hermetic, insulating electrical seals.

Link to Official Patent: Sealing Glass and Electrically Conductive Formulation

Keyword: Sealing Glass