Cooling for singulation of composite materials in molded...

Details Cooling for singulation of composite materials in molded... Cooling for singulation of composite materials in molded...

2000-11-15

2002-10-22

Capossela, Ronald (Department: 3744)

Refrigeration

Processes

Treating an article

C062S320000, C083S171000

Reexamination Certificate

active

06467278

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to integrated circuit packages. More specifically, the invention relates to the singulation of integrated circuit packages.
BACKGROUND OF THE INVENTION
An integrated circuit (IC) package encapsulates an IC chip (die) in a protective casing and may also provide power and signal distribution between the IC chip and an external printed circuit board (PCB). An IC package may use a metal lead frame to provide electrical paths for that distribution.
To facilitate discussion,
FIG. 1
is a top view of a top view of a lead frame panel
100
made up for a plurality of lead frames that may be used in the prior art. The lead frame may comprise leads
108
, die attach pads
112
, ties
116
for supporting the die attach pads
112
, and a skirt
120
for supporting the plurality of leads
108
and ties
116
. The lead frame panel
100
may be etched or stamped from a thin sheet of metal. IC chips
124
may be mounted to the die attach pads
112
by an adhesive epoxy. Wire bonds
128
, typically of fine gold wire, may then be added to electrically connect the IC chips
124
to the leads
108
. Each IC chip
124
may then be encapsulated with part of the leads
108
and the die attach pad
112
in a protective casing, which may be produced by installing a preformed composite, plastic or ceramic housing around each IC chip or by dispensing and molding a layer of encapsulation material (mold compound), such as a composite or plastic material, over all IC chips
124
.
FIG. 2
is a cross-sectional view of part of the lead frame panel
100
and IC chips
124
that has been encapsulated by an encapsulation material
140
, such as composite or plastic. The encapsulated IC chips are singulated. Dashed line
132
indicates a singulation line.
FIG. 3
is a bottom view of a single singulated encapsulated IC chip
300
. The encapsulation material
140
, die attach pad
112
and leads
108
are shown.
Since during the singulation process, the cutting of encapsuration material, metal leads, and silicon is achieved, the method of singulation is very critical. If a sawing method is used for singulation, the metal in the lead or frame may smear or burr due to heat generated by the sawing process. Other methods of singulation may be by laser or water jet, which may also generate heat and cause unwanted damage. Such singulation methods may cause the metal leads to smear, caused by melting, or burr, which may cause shorting between the leads. Solder or lead may also melt disrupting electrical connections. In
FIG. 3
, shorting
304
between the leads is shown.
It is desirable to provide an IC package singulation process, which reduces damage to the encapsulated IC packages, such as shorting, metal lead smear, melting, or burring.
SUMMARY OF THE INVENTION
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, a variety of techniques is provided for making packaged chips. Generally, a panel is placed in a singulating device. Fluid is placed in a chiller system. The fluid is cooled in the chiller system. The cooled fluid is provided to an area of the panel to be singulated. The panel is then singulated.
Another aspect of the invention provides an apparatus for singulating a panel of encapsulated dice. A singulating device for cutting the panel is provided. A chiller system for cooling a fluid is provided to the singulating device. A dispenser for directing the cooled fluid to an area of the panel being singulated is provided to the chiller system.
These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures.


REFERENCES:
patent: 2815562 (1957-12-01), Wilkie et al.
patent: 2838825 (1958-06-01), Knollenberg
patent: 3605551 (1971-09-01), Steward
patent: 4091580 (1978-05-01), Oates
patent: 4140046 (1979-02-01), Marbach
patent: 5207815 (1993-05-01), Wright
patent: 5678466 (1997-10-01), Wahl
patent: 6354285 (2002-03-01), Licht et al.

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