US 6,479,903 B2Granted

Flip chip thermally enhanced ball grid array

AssigneeST Assembly Test Services Ltd.

InventorJohn Briar

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Abstract

A new method is provided for the conduction of heat between a flip-chip and the motherboard and heatsink onto which the flip-chip is mounted. In a flip-chip package of the invention the heatsink is in direct contact with the flex circuit, the contact balls of the flip chip make contact with the flex circuit. The flip-chip is attached and reflow is performed thereby attaching the contact balls to the flex circuit. The flip chip is encased in a molding compound in a one step process procedure that is in accordance with assigned to a common assignee. The flip-chip is now placed on the motherboard with the contact balls and the underfill facing upwards. The underfill provides direct contact between the flip-chip and the flex circuit/heatsink. This direct contact significantly increases the heat flow between the flip-chip and the heatsink. The top surface of the flip-chip rests, after the flip-chip has been mounted onto the motherboard, on the motherboard thereby providing maximum heat flow between the top of the flip-chip and the motherboard.

An Integrated Circuit device package, comprising:

an Integrated Circuit (IC) device, said IC having been provided with first points of electrical contact;
a heat sink, an interconnect substrate for said Integrated Circuit device having been attached to a surface of said heatsink, said interconnect substrate having been provided with second points of electrical contact in a surface thereof;
said heatsink with the thereto attached interconnect substrate being positioned in close contact with said IC device, said first points of electrical contact being aligned with said second points of electrical contact;
said first and second points of electrical contact being reflowed, establishing electrical connections between said integrated circuit and said interconnect substrate;
said IC device being encased in a molding compound, including underfill for said Integrated Circuit device, said molding compound having a surface having a size;
a motherboard, said motherboard having a first surface with third points of electrical contact in addition to having a thermal shield in said first surface thereof, said thermal shield having a surface area of about the size of said surface of said molding compound;
contact balls having been placed on the surface of said motherboard;
said encased IC device having been placed on the surface of said motherboard, facing the first points of electrical contact upwards, further placing said surface of said molding compound on said thermal shield of said motherboard, at least one of said contact balls having been placed on the surface of said motherboard providing electrical contact between at least one of said second points of electrical contact of said interconnect substrate and at least one of said third points of electrical contact of said motherboard;
and
said contact balls having been placed on said motherboard being reflowed, connecting at least one of said contact balls placed on said motherboard with at least one of said first and second points of electrical contact.

7 more elements

Facts

Application

09/877,324Filed 11 Jun 2001 · division

Priority

4 Aug 1999

Published

US 2001/0026955 A14 Oct 2001

Granted

12 Nov 2002

Term ends

Not estimatedThe source records don’t support an estimate.

Classification18 codes

H10W 40/10
Arrangements for thermal protection or thermal control: arrangements for heating
H10W 72/30
Interconnections or connectors in packages: die-attach connectors
H10W 74/012
Manufacture or treatment: of encapsulations on active surfaces of flip-chip devices, e.g. forming underfills
H10W 74/15
Characterised by their shape or disposition: on active surfaces of flip-chip devices, e.g. underfills

Abstract

Claims8