Glass/ceramics replacement of epoxy for high temperature hermetically sealed non-axial electronic packages
View Patent ↗A high temperature, non-cavity package for non-axial electronics is designed using a glass ceramic compound with that is capable of being assembled and operating continuously at temperatures greater that 300-400° C. Metal brazes, such as silver, silver colloid or copper, are used to connect the semiconductor die, lead frame and connectors. The components are also thermally matched such that the packages can be assembled and operating continuously at high temperatures and withstand extreme temperature variations without the bonds failing or the package cracking due to a thermal mismatch.
1. The method for making a packaged semiconductor device comprising:
providing a metal plated pad, leadframe having at least one package site, the at least one package site having at least one lead;
mounting a semiconductor die on the at least one package site using a first metal braze, said first metal braze comprising a silver colloid;
bonding a connector to the semiconductor die and the at least one lead using a second metal braze, said second metal braze comprising said silver colloid; and
encapsulating and sealing the semiconductor die, the connector and at least part of the metal plated pad, leadframe and the at least one lead within a glass ceramic compound to form a hermetically sealed electronic package, wherein the package is non-cavity and void-less, and said glass ceramic compound is heated to chemically bond said glass ceramic compound to said metal plated pad, said semiconductor die and said connector;
wherein the connector, the metal plated pad, the leadframe, the semiconductor and the glass ceramic are thermally matched and wherein the glass ceramic has a CTE<5.0×10 −6 and a transition temperature>450° C.
2. The method of claim 1 , wherein the step of encapsulating and sealing comprises overmolding a slurry of the ceramic frit to fuse together around the semiconductor die, the connector and at least part of the leadframe and the at least one lead.
3. The method of claim 1 , wherein the step of encapsulating and sealing comprises of placing the semiconductor die, the connector and the at least part of the pad, leadframe and at least one lead between two plates of the ceramic glass and raising the temperature above the reflow temperature for the glass ceramic compound to fuse the plates together around the semiconductor die, the connector and the at least part of the pad, leadframe and the at least one lead.
4. The method of claim 1 , wherein the metal braze is thermally match with the glass ceramic.
5. The method of claim 1 , wherein the metal plated pad or leadframe comprises a tungsten or molybdenum substrate having a nickel layer sintered attached to copper leadframe thereon.
6. The method of claim 5 wherein the metal plated pad or leadframe further comprises a nickel plated layer thereon.
7. The method of claim 5 wherein the metal plated pad or leadframe further comprises a silver plated layer thereon.
8. The method of claim 1 , wherein the connector comprises a clip.
9. The method of claim 6 , wherein the clip comprises a nickel plated tungsten clip.
10. The method of claim 1 wherein the connector comprises a wire.
11. The method of claim 1 , wherein the glass ceramic comprises borosilicate glass.
12. The method of claim 1 , wherein the glass ceramic has a CTE between about 3.4-4.8×10 −6 .
13. The method of claim 1 , wherein the glass ceramic has a transition temperature between about 450° C.-550° C.
14. The method of claim 1 , wherein the metal plated pad, leadframe comprises a plurality of package cites, further comprising;
mounting a semiconductor die on each package site using a metal braze;
bonding a connector to each semiconductor die and the at least one lead at each package site using a metal braze; and
encapsulating and sealing each package site; and
singulating each encapsulated and sealed package site.