Microcircuit package and sealing method

• US 4,633,573 A
• Filed: 05/23/1984
• Issued: 01/06/1987
• Est. Priority Date: 10/12/1982
• Status: Expired due to Fees

• Current Assignee: Aegis Incorporated (Eclat Textile Company Limited)
• Original Assignee: Aegis Incorporated (Eclat Textile Company Limited)
• Inventors: Scherer, Jeremy D.
• Primary Examiner(s): Hearn, Brian E.
• Assistant Examiner(s): Hey, David A.
• Application Number:
  US06/613,367
• Time in Patent Office: 958 Days
• Field of Search: 174/52 FP, 174/52 PE, 357/72, 357/73, 29/589, 29/591, 427/123, 427/124, 204/45.1
• US Class Current: 29/841
• CPC Class Codes: H01L 21/50 Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48464 the other connecting portion not on the bonding area also being a ball bond, i.e. ball-to-ball
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/057 the leads being parallel to the base
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/15153 the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/15165 Monolayer substrate
• CPC Class Codes: H01L 2924/1517 Multilayer substrate
• CPC Class Codes: H01L 2924/16152 Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: Y10T 29/49146 : with encapsulating, e.g., potting, etc.

Abstract

A microcircuit package and sealing method in which a non-organic coating is used to hermetically seal the microcircuit. The microcircuit is isolated and insulated in order to protect the microcircuit from the high temperatures required to apply and cure a non-organic coating. The materials and methods used to isolate and insulate the microcircuit are chosen so that the thermal coefficients of the materials are complementary and thus form a highly reliable, durable seal, while also insulating the microcircuit during the process of applying the non-organic coating.

Claims

1. The method of hermetically sealing a microcircuit mounted on a package having a continuous perimeter sealing surface of random shape independent of the hermetic seal to be applied comprising the steps of:

isolating the microcircuit and insulating the microcircuit to protect it from contamination and heat by forming a thermal barrier over the microcircuit sufficient to prevent the microcircuit from being damaged by the heat of applying a non-organic coating over the thermal barrier; and

hermetically sealing the microcircuit by applying a non-organic coating over the thermal barrier whereby the non-organic coating overlaps the continuous perimeter sealing surface so that the non-organic coating fuses to the sealing surface in order to hermetically seal the microcircuit package.

2. The method of claim 1 wherein the steps of isolating and insulating the microcircuit comprise encapsulating the microcircuit in an encapsulating coating and applying a protective layer over said coating.

3. The method of claim 2 wherein said protective layer is a ceramic material.

4. The method of claim 3 wherein the thermal coefficients of the encapsulating coating, the protective layer, and the non-organic coating are complementary.

5. The method of claim 4 wherein said encapsulating coating can withstand temperatures of at least 390°

F. and said ceramic material can withstand temperatures of at least 3000°

F.

6. The method of claim 1 wherein the step of applying a non-organic coating comprises spraying said non-organic coating in an inert atmosphere.

7. The method of claim 1 wherein the step of applying a non-organic coating comprises an evaporating deposition of the non-organic coating.

8. The method of claim 1 wherein the step of applying a non-organic coating comprises an electroplating deposition of the non-organic coating.

9. The method of claim 1 wherein the step of hermetically sealing the microcircuit comprises bonding the non-organic coating to a seal ring defining the continuous perimeter sealing surface.

10. The method of claim 1 wherein the steps of isolating and insulating the microcircuit comprises forming a cavity over the microcircuit thus providing an atmosphere space over the microcircuit.

11. The method of claim 10 wherein the step of forming a cavity comprises fastening a ceramic spacer over the microcircuit.

12. The method of claim 1, 3 or 11 further comprising the step of metallizing said sealing surface and wherein said non-organic coating is a metal, and wherein the step of hermetically sealing the microcircuit comprises bonding the metal coating to said metallized sealing surface.

13. The method of claim 1, 3 or 11 wherein said non-organic coating is a glass, and wherein the step of hermetically sealing the microcircuit comprises applying the glass coating to a continuous perimeter sealing surface of the package.

14. A method of hermetically sealing a microcircuit mounted in a cavity on a microcircuit package, comprising the steps of:

providing a continuous perimeter sealing surface of random shape independent of the hermetic seal to be applied around the cavity;

forming a thermal barrier over said microcircuit by covering said microcircuit with at least one protective layer;

applying a non-organic sealing material on top of said protective layer so that said non-organic sealing material overlaps and fuses to said sealing surface and thereby forms a hermetic seal on said continuous perimeter sealing surface.

15. The method of claim 14 further comprising the step of metallizing said continuous perimeter sealing surface and wherein said non-organic sealing material is a metal, said protective layer is a ceramic material, and further comprising the step of transporting said microcircuit in an inert atmosphere on a conveyor which acts as a heat sink.

16. The method of claim 14 wherein said sealing material is a glass, said protective layer is a ceramic material, and further comprising the step of transporting said microcircuit in an inert atmosphere on a conveyor which acts as a heat sink.

17. The method of claim 15 or 16 wherein said inert atmosphere is nitrogen, helium, or a mixture of nitrogen and helium.

18. The method of claim 14, 15 or 16 further comprising the step of encapsulating the microcircuit in a coating which fills the cavity.

19. The method of hermetically sealing a microcircuit package comprising:

(a) connecting a microcircuit in a cavity of a microcircuit package having electrical leads so that a complete electrical circuit is obtained between the microcircuit and the electrical leads;

(b) providing a continuous perimeter sealing surface of random shape on the microcircuit package;

(c) forming a thermal barrier over the microcircuit by encapsulating the microcircuit in a coating, which is applied and cured at a temperature which will not damage the microcircuit, in order to isolate and insulate the microcircuit;

(d) covering the encapsulated microcircuit with a material, which may be applied and cured at a temperature which will not damage the microcircuit, said material further insulating the microcircuit; and

(e) transporting the package on a conveyor having enough thermal mass to act as a heat sink past a series of sprayers which spray a non-organic coating over the cavity and surrounding continuous perimeter sealing surface so that the non-organic coating and the sealing surface fuse together to form a hermetic seal for the microcircuit package.

20. The method of hermetically sealing a microcircuit package comprising:

(a) connecting a microcircuit in a cavity of a microcircuit package having electrical leads so that a complete electrical circuit is obtained between the microcircuit and the electrical leads;

(b) providing a continuous perimeter sealing surface of random shape on the microcircuit package;

(c) forming a thermal barrier over the microcircuit by bonding a spacer in the microcircuit package to form an atmosphere space over the microcircuit to insulate the microcircuit;

(d) transporting the package on a conveyor having enough thermal mass to act as a heat sink past a series of sprayers which spray a non-organic coating over the cavity and surrounding continuous perimeter sealing surface so that the non-organic coating and the sealing surface fuse together to form a hermetic seal for the microcircuit package.