Data processing: structural design – modeling – simulation – and em – Simulating nonelectrical device or system – Fluid
Reexamination Certificate
2001-09-27
2004-06-08
Thomson, W. (Department: 2123)
Data processing: structural design, modeling, simulation, and em
Simulating nonelectrical device or system
Fluid
C703S001000, C703S005000, C703S012000, C438S118000, C438S122000, C257S706000, C257S709000, C361S704000, C361S709000, C361S705000, C374S043000, C374S044000, C374S057000
Reexamination Certificate
active
06748350
ABSTRACT:
FIELD
The inventive subject matter relates to a device and method to control strain and tensile stress on thermal interface material in a heat spreader. More particularly, the inventive subject matter pertains to a device and method that determine stress points in thermal interface material used to transfer heat from a die to a heat spreader and design the heat spreader to optimize the thickness of thermal interface material for those stress points.
BACKGROUND
In the rapid development of computers many advancements have been seen in the areas of processor speed, throughput, communications, fault tolerance and size of individual components. Today's microprocessors, memory and other chips have become faster and smaller. However, with the increase in speed, reduction in the size of components, and increased density of circuitry found within a given chip/die, heat generation and dissipation have become more critical factors than ever.
FIG. 1
illustrates a die
50
placed on a substrate
30
with a finite amount of a thermal interface material (TIM)
20
placed on top of the die
50
. This TIM
20
serves at least two primary purposes. First, it acts to conduct heat from the die to the integrated heat spreader (IHS)
10
. Second, it may also provide some adhesion between the IHS
10
and die
50
. The TIM
20
may be composed of, but not be limited to, solder, a polymer containing metal, or some other substances which both act to transfer heat and provide some adhesion. During the manufacturing process the IHS
10
is pressed down upon the TIM
20
and adhesive
40
, resulting in a structure as shown in FIG.
2
.
As shown in
FIG. 2
, the IHS
10
would absorb heat from die
50
through TIM
20
and be held in place on the substrate
30
via adhesive
40
. On top of the IHS
10
a heat sink (not shown) or fan/heat sink combination (not shown) would be mounted to dissipate the heat absorbed by the IHS
10
. However, since IHS
10
and TIM
20
both experience significant tensile stress during the assembly process and due to thermal expansion and contraction when the die is powered on and off, as shown in
FIG. 3
, air gaps
60
form between the TIM
20
and IHS
10
. As indicated in
FIG. 3
, these air gaps
60
may form at the outer edges of the TIM
20
while the center portion of the TIM
20
remains in contact with the IHS
10
.
However, as shown in
FIGS. 3 and 4
, an air gap
60
may occur anywhere in the contact area between TIM
20
and IHS
10
. As illustrated in
FIG. 4
, an air gap
60
may form in the center of the contact area between the TIM
20
and IHS
10
, while the outer edges of the TIM
20
remain in contact with the IHS
10
.
As would be appreciated by one of ordinary skill in the art, these air gaps
60
shown in
FIGS. 3 and 4
may form anywhere in the contact area between the TIM
20
and IHS
10
depending on the materials utilized in the IHS
10
and TIM
20
as well as the handling procedures for the IHS
10
during the manufacturing process. Further, these air gaps
60
may also form in the TIM
20
itself. It should be noted that
FIGS. 3 and 4
, except for the inclusion of air gaps
60
, remain unchanged from that shown in FIG.
2
and will not be discussed in further detail.
Since separation may occur between the TIM
20
and IHS
10
, forming air gaps
60
, as shown in
FIGS. 3 and 4
, due to thermal expansion and contraction, these air gaps
60
act as insulation, preventing heat being transferred from the die
50
to the IHS
10
. As heat builds up in the die
50
to higher levels, the life expectancy of the die
50
is reduced.
Therefore, what are needed are a device and method that can determine the stress points between the TIM
20
and IHS
10
due to thermal expansion and contraction. Further, what are needed are a device and method that may compensate for the tensile and shear stress, thereby preventing the separation of the TIM
20
and the IHS
10
. Still further, what are needed are a device and method that will provide for efficient heat transfer from the die
50
to the IHS
10
.
REFERENCES:
patent: 4683750 (1987-08-01), Kino et al.
patent: 5367196 (1994-11-01), Mahulikar et al.
patent: 5402006 (1995-03-01), O'Donley
patent: 5591034 (1997-01-01), Ameen et al.
patent: 5749988 (1998-05-01), Leibovitz et al.
patent: 5834339 (1998-11-01), Distefano et al.
patent: 5847929 (1998-12-01), Bernier et al.
patent: 6002171 (1999-12-01), Desai et al.
patent: 6091603 (2000-07-01), Daves et al.
patent: 6117695 (2000-09-01), Murphy et al.
patent: 6169328 (2001-01-01), Mitchell et al.
patent: 6188582 (2001-02-01), Peter
patent: 6238086 (2001-05-01), Mikubo et al.
patent: 6288900 (2001-09-01), Johnson et al.
patent: 6333551 (2001-12-01), Caletka et al.
patent: 6396700 (2002-05-01), Chu et al.
“FLomerics Incroduces FLOPACK for the Thermal Modeling of Electronic Packages”, Oct. 1998.*
Valenta, “Thermal Modeling of Ball Grid Arrarys”, Sep. 1996.*
Cheng et al., “iCET: A Complete Chip Level Thermal Reliability Diagnosis Tool for CMOS VLSI”, ACM 1996.*
Bosak, “A3-D thermal Analysis of Microprocessors”, FLOTHERM International USER Conference Presentations, May 1993.*
Mansingh et al., thermal Analysis of a Pin Grid Array Package, Flomerics, 1993.*
Burdick, “Electronic Cooling at IBM Endicott”, IBM, Aug. 1991.*
Jeakins, “Thermal Analysis of a Ceramic Microelectronics Package Using Flotherm”, FLOTHERM International User Conferenc Presentations, May 1993.*
Rosten et al., “DELPHI: The Development of Libraries of Physical Components for an Integrated Design Environment”, Flomerics, 1996.*
Rosten et al., “Final Reports to SEMITHERM XIII on the European Funded Project DELPHI the Development of Libraries and Physical Models for an Integrated Design Environment”, Flomerics, 1996.*
Ashium Haque, “Processing and Characterization of Device Solder Interconnection and Module Attach for Power Electronics Modules”, Chapter 4, pp. 71-108, Dec. 1999.*
Kromann, Gary B., “Thermal Modeling and Experimental Characterization of the C4/Surface-Mount-Array Interconnect Technologies”,IEEE Transactions on Components, Packaging, and Manufacturing Technology, Part A, vol. 18, No. 1, (Mar. 1995), pp. 87-93.
Houle Sabina J.
Rumer Christopher L.
LandOfFree
Method to compensate for stress between heat spreader and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method to compensate for stress between heat spreader and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method to compensate for stress between heat spreader and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3363335