Chip package with grease heat sink and method of making

• US 20020052105A1
• Filed: 12/28/2001
• Published: 05/02/2002
• Est. Priority Date: 08/31/1999
• Status: Active Grant

• Current Assignee: Salman Akram
• Original Assignee: Salman Akram
• Inventors: Akram, Salman
• Granted Patent: US 6,919,220 B2
• Time in Patent Office: Days
• US Class Current: 438/613
• CPC Class Codes: H01L 21/563 Encapsulation of active face of flip-chip device, e.g. underfilling or underencapsulation of flip-chip, encapsulation preform on chip or mounting substrate
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/06135 Covering only the peripheral area of the surface to be connected, i.e. peripheral arrangements
• CPC Class Codes: H01L 2224/06136 Covering only the central area of the surface to be connected, i.e. central arrangements
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32145 the bodies being stacked
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/4824 Connecting between the body and an opposite side of the item with respect to the body
• CPC Class Codes: H01L 2224/73203 Bump and layer connectors
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/83951 Forming additional members, e.g. for reinforcing, fillet sealant
• CPC Class Codes: H01L 2225/0651 Wire or wire-like electrical connections from device to substrate
• CPC Class Codes: H01L 2225/06513 Bump or bump-like direct electrical connections between devices, e.g. flip-chip connection, solder bumps
• CPC Class Codes: H01L 2225/06517 Bump or bump-like direct electrical connections from device to substrate
• CPC Class Codes: H01L 2225/0652 Bump or bump-like direct electrical connections from substrate to substrate
• CPC Class Codes: H01L 2225/06555 Geometry of the stack, e.g. form of the devices, geometry to facilitate stacking
• CPC Class Codes: H01L 2225/06572 : Auxiliary carrier between devices, the carrier having an electrical connection structure
• CPC Class Codes: H01L 2225/06582 : Housing for the assembly, e.g. chip scale package [CSP]
• CPC Class Codes: H01L 2225/06586 : Housing with external bump or bump-like connectors
• CPC Class Codes: H01L 2225/06589 : Thermal management, e.g. cooling
• 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 23/3114 : the device being a chip scale package, e.g. CSP
• CPC Class Codes: H01L 23/3128 : the substrate having spherical bumps for external connection
• CPC Class Codes: H01L 23/3675 : characterised by the shape of the housing
• CPC Class Codes: H01L 23/3737 : Organic materials with or without a thermoconductive filler
• CPC Class Codes: H01L 23/42 : Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
• CPC Class Codes: H01L 23/4334 : Auxiliary members in encapsulations H01L23/49568 takes precedence
• CPC Class Codes: H01L 24/31 : Structure, shape, material or disposition of the layer connectors after the connecting process
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 25/0657 : Stacked arrangements of devices
• 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 2924/00014 : 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 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• 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 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/1532 : the connection portion being formed on the die mounting surface of the substrate
• CPC Class Codes: H01L 2924/15331 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/16151 : Cap comprising an aperture, e.g. for pressure control, encapsulation
• CPC Class Codes: H01L 2924/16152 : Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H01L 2924/18161 : of a flip chip

Abstract

The present invention relates to enhanced protection of the active surface and the bond wires or ball array of a microelectronic device, and to thermal management of the microelectronic device as it is package with a printed circuit board (PCB) or other substrate. The enhanced protection and thermal management are accomplished with a high-temperature thermal grease that is glob topped or encapsulated over the bond wires or ball array, and the active surface of the microelectronic device. The high-temperature thermal grease exchanges heat, particularly by conduction, away from the active surface of the microelectronic device as well as away from the bond wires.

Claims

1. A method of making an IC chip package having an IC chip with an active surface, the active surface having extending therefrom an electrical connector in electrical communication with IC chip, the IC chip being mounted upon a substrate, the method comprising:

providing a container disposed upon the substrate; and

injecting a grease in contact with the active surface of the IC chip such that the grease is;

enclosed by the container and the substrate; and

is in contact with the active surface and the electrical connector.

2. The method as defined in claim 1, further comprising:

securing the container to the substrate with a dam structure that contacts the grease.

3. The method as defined in claim 1, further comprising:

operating the IC chip to generate heat therefrom;

conducting the heat from the IC chip and the electrical connector to the grease, to the container, and to the ambient.

4. The method as defined in claim 1, wherein the grease has a thermal conductivity that is less than a thermal conductivity of the container.

5. The method as defined in claim 1, wherein the grease has:

a thermal conductivity in a range from about 2 Watts/m·

K to about 5 Watts/m·

K;

a dielectric constant in a range from less than about 6 to about 9; and

a melting point in a range from about 190°

C. to about 220°

C.

6. The method as defined in claim 1, wherein the IC chip package comprises IC chip elements, wherein the container disposed upon the substrate encloses a volume external to the IC chip elements, and wherein the injecting a grease comprises the filling with the grease of the volume enclosed by the container.

7. The method as defined in claim 1, wherein the container is in contact with the active surface of the IC chip.

8. The method as defined in claim 1, wherein a flip chip is disposed over the active surface of the IC chip, wherein the container is a dam structure, and wherein the dam structure is in contact with each of the IC chip, the flip chip, and the grease.

9. The method as defined in claim 5, wherein the IC chip package comprises IC chip elements, wherein the container disposed upon the substrate encloses a volume external to the chip elements, and wherein injecting a grease comprises the filling by the grease of the volume enclosed by the container.

10. The method as defined in claim 5, wherein a flip chip is disposed over the active surface of the IC chip, wherein the container is a dam structure, and wherein the dam structure is in contact with each of the IC chip, the flip chip, and the grease.

11. The method as defined in claim 6, wherein the container comprises a metal that has a thermal conductivity greater than the thermal conductivity of the grease.

13. The method as defined in claim 12, further comprising:

operating the flip chip to generate heat therefrom;

conducting the heat from the flip chip and the electrical connector to the grease, to the container, and to the ambient.

14. The method as defined in claim 12, wherein the substrate is a flex substrate.

15. The method as defined in claim 12, wherein the grease has:

a thermal conductivity in a range from about 2 Watts/m·

K to about 5 Watts/m·

K;

a dielectric constant in a range from less than about 6 to about 9; and

a melting point in a range from about 190°

C. to about 220°

C.

17. The method as defined in claim 16, further comprising:

providing a third IC chip having an active surface and being disposed over the first side of the BOC substrate and over the second IC chip such that the grease is in contact with the active surface of the third IC chip.

18. The method as defined in claim 16, further comprising:

operating the first, second, and third IC chips to generate heat therefrom; and

conducting the heat from the electrical connector and from the first, second, and third IC chips to the grease, to the container, and to the ambient.

19. The method as defined in claim 16, wherein the grease has:

a thermal conductivity in a range from about 2 Watts/m·

K to about 5 Watts/m·

K;

a dielectric constant in a range from less than about 6 to about 9; and

a melting point in a range from about 190°

C. to about 220°

C.

20. The method as defined in claim 16, further comprising:

generating heat from at least one of the IC chips by operating said at least one of the IC chips; and

allowing the heat to propagate to the grease and to the container.

12. A method of making an IC chip package having a flip chip with an inactive surface and an active surface, the active surface having extending therefrom an electrical connector in electrical communication with flip chip, the flip chip being mounted upon a substrate, the method comprising:

providing a container disposed upon the substrate and in contact with the inactive surface of the flip chip; and

injecting a grease between the contact and the substrate so as to contact with the active surface of the flip chip, wherein;

the container with the substrate encloses the grease, the electrical connector, and the flip chip;

the grease is in contact with the active surface and the electrical connector.

16. A method of making an IC chip package having a first IC chip with an active surface, the active surface having extending therefrom an electrical connector in electrical communication with the first IC chip, the first IC chip being mounted upon a first side of a board-on-chip (BOC) substrate having said first side that is opposite a second side thereof, the method comprising:

providing a second IC chip having an active surface and being disposed over the first side of the BOC substrate;

providing a container disposed upon the BOC substrate; and

injecting a grease between the BOC substrate and the container;

wherein the grease;

is in contact with the electrical connector and with the active surfaces of each of the first and second IC chips; and

is enclosed within the container and the substrate.