Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2002-09-19
2004-12-28
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C165S080200, C165S080300, C165S185000, C257S707000, C257S712000, C257S719000, C361S710000, C361S719000, C361S720000
Reexamination Certificate
active
06836408
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates to electronic packaging and more specifically to bare die electronic packaging.
2. Description of the Related Art
Generally, integrated circuits are packaged using electronic packages with a lid (lidded) or without a lid (lidless or bare). In lidded electronic packaging, the lid serves as cover for the integrated circuit die to prevent structural damages and provides a mechanism to transfer force from the top of the electronic package to a circuit board on which the electronic package is installed. For bare or lidless electronic packages, the force transfer occurs through the integrated circuit die itself. The magnitude of force applied to the bare electronic package is typically smaller than the lidded electronic package to insure the structural integrity of the integrated circuit die.
Bare electronic packages have thermal advantage over lidded electronic packages. Eliminating the lid and thermal interface material from the lidded electronic package provides lower thermal resistance and better thermal performance for bare electronic package. Better thermal performance is critical for electronic packages with higher total power dissipation. Therefore, electronic circuits with high total power dissipation are typically packaged using bare electronic packaging. However, the amount of force that can be used on bare electronic packages is limited compared to the lidded electronic package. The limited force applicability can result in improper function such as, for example, the electronic package may not be properly inserted into a circuit board, or a cooling radiator may not establish proper conductive interface with the integrated circuit die resulting in poor thermal performance.
FIG. 1A
illustrates an example of a typical use of a bare die electronic package with a cooling radiator. A circuit board assembly
100
includes a circuit board
110
. A bare die electronic package with a substrate
120
and a bare die
130
is coupled to circuit board
110
. Bare die
130
conductively interfaces with a cooling radiator
140
via a thermal interface material
150
. Bare die
130
may not provide enough surface contacts for cooling radiator
140
for proper attachment. Thus, additional fastening mechanism is used for cooling radiator
140
. Typically, cooling radiator
140
is further strengthened by two fastening bolts
170
and
175
. However, other conventional means can be used to fasten cooling radiator
140
. Often, bolts
170
and
175
cannot be fastened directly on circuit board
110
(e.g., due to the circuit layout, other electronic components, or the like) therefore, an additional bolster plate
160
is used to provide support for bolts
170
and
175
.
The typical arrangement shown in
FIG. 1A
results in empty space
180
around bare die
130
under cooling radiator
140
. Empty space
180
limits the amount of force that can be applied using bolts
170
and
175
. Because empty space
180
does not provide guiding support underneath cooling radiator
140
, applying additional fastening force on bolts
170
and
175
can result in the bending of cooling radiator
140
or it can cause structural damage to bare die
130
. Empty space
180
around bare die
130
limits the amount of force that can be applied on bare die
130
.
FIG. 1B
illustrates the top view of circuit board
110
without cooling radiator
140
. The surface area with thermal interface material
150
on bare die
130
is generally smaller compared to empty space
180
around bare die
130
on substrate
120
. When a force is applied to bolts
170
and
175
to fasten cooling radiator
140
to bare die
130
then due to empty space
180
around bare die
130
, the force is centered on bare die
130
. To prevent the structural integrity of bare die
130
, the amount of force that can be applied using bolts
170
and
175
is often significantly limited. The limited force can leave cooling radiator
140
without a proper conductive interface with bare die
130
and can cause poor thermal performance for bare die
130
. Similarly, when cooling radiators are not needed for some bare electronic packages, the amount of force that can be applied to insert bare electronic packages into circuit boards can also be limited resulting in improper functioning of the integrated circuits. Therefore, a method and an apparatus are needed to allow parallel force transfer through a bare die electronic package.
SUMMARY
In some embodiments, the present application describes a method and an apparatus for facilitating increased uniformity and diffusion of force transfer on a bare die electronic package for example, when such electronic package is attached to a circuit board. Additional force absorbent material is applied around a bare die in the bare die electronic package. The force applied to the bare die electronic package can be distributed to the additional force absorbent material. A curable force absorbent material is dispensed around the bare die in the bare die electronic package. The surface of the curable material is substantially parallel with the surface of bare die thus facilitating a substantially uniform force distribution through the bare die and curable material
0
resulting in a robust bare die electronic package.
In an embodiment, a method in connection with electronic packaging is described. In some variations, the method includes dispensing a curable material, substantially covering an area around a die in a bare die electronic package, wherein a surface of the curable material is substantially parallel with a surface of the die. In some variation, the die is integral with a substrate. According to an embodiment, the bare die electronic package is installed on a circuit board. In an embodiment, the method includes curing the curable material. In some variation, the curable material substantially forms a frame around the die.
In an embodiment, an electronic package is described. According to an embodiment, the electronic package includes a die and a substrate integral with the die. In some variation, a curable material is dispensed substantially around the die and a surface of the curable material is substantially parallel with a surface of die. In some variation, the electronic package is a bare die electronic package. In some variation, the electronic package is installed on a circuit board. In some variation, the curable material forms a frame around the die on the substrate. In some variation, the frame substantially covers the substrate.
REFERENCES:
patent: 5450283 (1995-09-01), Lin et al.
patent: 6229702 (2001-05-01), Tao et al.
patent: 6390475 (2002-05-01), Eckblad et al.
patent: 6442026 (2002-08-01), Yamaoka
Gektin Vadim
Jones James A.
Sun Microsystems Inc.
Zagorin O'Brien & Graham LLP
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