Method of protecting micropackages from their environment

• US 4,063,349 A
• Filed: 12/02/1976
• Issued: 12/20/1977
• Est. Priority Date: 12/02/1976
• Status: Expired due to Term

• Current Assignee: Honeywell Information Systems, Inc. (Honeywell International Inc.)
• Original Assignee: Honeywell Information Systems, Inc. (Honeywell International Inc.)
• Inventors: Fredenberg, James David, Passler, Herbert Edwin
• Primary Examiner(s): McGehee, Travis S.
• Application Number:
  US05/746,755
• Time in Patent Office: 383 Days
• Field of Search: 53/7, 53/22 R, 53/22 A, 53/86, 29/627
• US Class Current: 29/841
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence
• CPC Class Codes: H05K 5/064 sealed by potting, e.g. waterproof resin poured in a rigid casing
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.

Abstract

A method of protecting active and passive electronic components on a portion of one surface of a multilayer substrate of a micropackage from deleterious constituents of the ambient atmosphere, primarily water vapor. A segment of a thin, flexible, substantially nonpermeable and nonadhering membrane, or sheet, has its perimeter secured to the substrate by a bead of sealant adhesive. The exposed surface of the segment has applied to it a thicker coating of a substantially nonpermeable sealant adhesive material which adheres to the membrane and the bead of sealant adhesive. A small opening is formed through the coating and the segment to provide communication with the area between the surface of the substrate on which the components are mounted and the inner surface of the segment. The substrate is placed in a chamber which is substantially evacuated to remove gases trapped under the segment. The opening formed through the coating and the segment is sealed by a drop of adhesive sealant while the substrate is in the evacuated chamber.

Claims

1. A process for protecting from the ambient environment components mounted on a component area of a surface of a substrate, said component area having a perimeter;

said process comprising the steps of;

a. cutting a segment of a substantially nonpermeable flexible membrane to a shape that is substantially congruent with the perimeter of the component area of the substrate, said segment having an inner and outer surface,

b. attaching the segment to the perimeter of the component area with a sealant adhesive,

c. coating the outer surface of the segment with a layer of substantially impermeable material that adheres to the membrane and to the sealant adhesive,

d. forming a small opening through the layer and the segment,

e. subjecting the substrate to substantially reduced pressure, and

f. sealing the opening formed through the layer and the segment with an adhesive sealant while the substrate is subjected to such a reduced pressure.

2. The method of claim 1 in which the membrane from which the segment is cut is made of a material selected from the group consisting of polyesters, polyvinyl fluorides, polyvinylidene chlorides, latex rubbers, and cellulose.

3. The method of claim 2 in which the thickness of the segment is in the range of from 0.001 to 0.005 inches.

4. A method for protecting active and passive electronic components mounted within a given component area of one substantially planar surface of a multilayer substrate from the ambient environment, said component area having a perimeter, said method comprising the steps of:

a. cutting a segment of a thin membrane made of a material substantially nonpermeable to water vapor to a size that substantially covers the area of the substrate on which the components are mounted, said segment having a perimeter that substantially coincides with the perimeter of the component area of the substrate and having an inner and an outer surface;

b. attaching the perimeter of the segment to the substrate substantially at the perimeter of the component area with a sealant adhesive;

c. coating the outer surface of the membrane with a layer of a sealant adhesive having a thickness substantially greater than the thickness of the membrane, said layer of sealant adhesive adhering to the outer surface of the membrane and to the sealant adhesive;

d. forming a small opening through the layer and the segment;

e. subjecting the substrate to substantially reduced atmospheric pressure substantially in the range of one inch of mercury; and

,

f. sealing the opening formed through the layer and the segment with a sealant adhesive while the substrate is subjected to such substantially reduced atmosphere.

5. The method of claim 4 in which the membrane from which the segment is cut is made of a material selected from the group consisting of polyesters, polyvinyl fluorides, polyvinylidene chlorides, latex rubbers, and celluloses.

6. The method of claim 5 in which the thickness of the membrane is in the range of from 0.001 to 0.005 inches.

7. A method for protecting a plurality of large scale integrated circuit chips and passive electronic components mounted within a component area on a substantially planar surface of a multilayer substrate from the ambient environment, said component area having a perimeter, said method comprising the steps of:

a. securing a vertical riser to the perimeter, said riser having an inner wall;

b. forming a segment of a thin nonpermeable nonadherable membrane to a shape that substantially covers the component area of the substrate and the components mounted on the substrate in the component area, said membrane having a perimeter that substantially contacts the inner wall of the riser, said segment having an inner and outer surface;

c. attaching the perimeter of the segment to the inner wall of the riser with a bead of room temperature vulcanizing silicone adhesive sealant;

d. coating the outer surface of the segment with a substantial layer of substantially impermeable silicone adhesive sealant which is substantially thicker than the membrane of said segment and which adheres to the outer surface of the segment and to the bead of sealant adhesive;

e. forming an opening through the coating and the segment;

f. placing the substrate in a chamber and substantially reducing the atmospheric pressure in the chamber; and

g. sealing the opening formed through outer layer and the segment with a room temperature vulcanizing silicone adhesive sealant while the substrate remains in the chamber at such a reduced atmospheric pressure.

8. The method of claim 7 in which the membrane of the segment is made of a material selected from the group consisting of polyesters, polyvinyl fluorides, polyvinylidene chlorides, latex rubbers, and cellulose.

9. The method of claim 8 in which the thickness of the segment is in the range of from 0.001 to 0.005 inches.

10. The method of claim 9 in which the thickness of the layer is in the range of from 0.010 to 0.015 inches.