US 7,253,078 B1Granted

Method and apparatus for forming an underfill adhesive layer

AssigneeNational Semiconductor Corporation

InventorsLuu T. Nguyen, Hau T. Nguyen, Viraj A. Patwardhan, Nikhil Kelkar, Shahram Mostafazadeh

Life of this patent

Estimating the term…

Loading patent…

Abstract

An apparatus and method for forming a layer of underfill adhesive on an integrated circuit in wafer form is described. In one embodiment, the layer of underfill adhesive is disposed and partially cured on the active surface of the wafer. Once the underfill adhesive has partially cured, the wafer is singulated. The individual integrated circuits or die are then mounted onto a substrate such as a printed circuit board. When the solder balls of the integrated circuit are reflowed to form joints with corresponding contact pads on the substrate, the underfill adhesive reflows and is completely cured. In an alternative embodiment, the underfill adhesive is fully cured after it is disposed onto the active surface of the wafer.

Claims32

Dependent claims

A method, comprising:

fabricating a plurality of integrated circuit dice on an active surface of a wafer;
fabricating one or more electrically conductive pads on each of the dice on the active surface of the wafer respectively;
forming solder bumps on the one or more electrically conductive pads on each of the dice on the active surface of the wafer respectively;
applying a layer of underfill adhesive on the active surface of the wafer, the layer of underfill covering the plurality of integrated circuit dice on the active surface of the wafer;
and
partially curing the layer of underfill adhesive applied to the active surface of the wafer,
wherein the curing the underfill adhesive after depositing the underfill involves only partially curing the underfill adhesive without fully curing the underfill adhesive so that the underfill adhesive may be further cured when the associated solder bumps are reflowed to electrically connect the integrated circuit dice to substrates respectively wherein the underfill adhesive includes at least once of the following properties:
a specificity of gravity ranging from 1.0 to 1.2;
a solvent content ranging from 20% to 40% a cure time of 20 to 30 minutes at 100 to 130 degrees C.;
and a filler content of 1% to 10% by weight.

7 more elements

A method, comprising:

fabricating a plurality of integrated circuit dice on an active surface of a wafer;
fabricating one or more electrically conductive pads on each of the dice on the active surface of the wafer respectively;
forming solder bumps on the one or more electrically conductive pads on each of the dice on the active surface of the wafer respectively;
after forming the solder bumps, applying a layer of underfill adhesive on the active surface of the wafer, the layer of underfill covering the plurality of integrated circuit dice on the active surface of the wafer;
and
partially curing the layer of underfill adhesive applied to the active surface of the wafer,
wherein the curing the underfill adhesive after depositing the underfill involves only partially curing the underfill adhesive without fully curing the underfill adhesive so that the underfill adhesive may be further cured when the associated solder bumps are reflowed to electrically connect the integrated circuit dice to substrates respectively wherein the underfill adhesive includes at least once of the following properties:
a specificity of gravity ranging from 1.0 to 1.2;
a solvent content ranging from 20% to 40% a cure time of 20 to 30 minutes at 100 to 130 degrees C.;
and a filler content of 1% to 10% by weight.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/224,291Filed 19 Aug 2002 · continuation in part
Priority: 22 Jul 1999
Granted: 7 Aug 2007
Term ends: Not estimatedThe source records don’t support an estimate.

Classification30 codes

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
H10D 62/117
Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies: shapes of semiconductor bodies
H10W 72/01223
Using local deposition: in liquid form, e.g. by dispensing droplets or by screen printing