U.S. patent application number 09/952303 was filed with the patent office on 2002-04-04 for heat sink provided with coupling means, memory module attached with the heat sink and maunfacturing method thereof.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Han, Seong-Chan, Lee, Dong-Chun, Lee, Wang-Jae, Shin, Dong-Woo.
Application Number | 20020039282 09/952303 |
Document ID | / |
Family ID | 19691130 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020039282 |
Kind Code |
A1 |
Han, Seong-Chan ; et
al. |
April 4, 2002 |
Heat sink provided with coupling means, memory module attached with
the heat sink and maunfacturing method thereof
Abstract
A novel heat sink structure for being mounted to a module board
to which semiconductor chips are attached and for dissipating or
spreading heat generated from the semiconductor chips is disclosed.
The heat sink comprises a heat sink base, and a coupling means for
coupling the heat sink base to the module board. The coupling means
passes through the heat sink base. The coupling means includes
integrally formed upper and lower body portions, an orifice formed
at least through the lower body portion, and a flanged base formed
integral with the lower body portion. The flanged base fixes the
coupling means to the heat sink base. The outer dimension of the
upper body portion is smaller than the inner dimension of the lower
body portion. As a result, many heat sinks can be stacked
stably.
Inventors: |
Han, Seong-Chan;
(Chungcheongnam-do, KR) ; Shin, Dong-Woo;
(Chungcheongnam-do, KR) ; Lee, Dong-Chun;
(Chungcheongnam-do, KR) ; Lee, Wang-Jae;
(Chungcheongnam-do, KR) |
Correspondence
Address: |
MARGER JOHNSON & McCOLLOM, P.C.
1030 S.W. Morrison Street
Portland
OR
97205
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
Suwon-city
KR
|
Family ID: |
19691130 |
Appl. No.: |
09/952303 |
Filed: |
September 12, 2001 |
Current U.S.
Class: |
361/719 |
Current CPC
Class: |
G11C 5/04 20130101 |
Class at
Publication: |
361/719 |
International
Class: |
H05K 007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2000 |
KR |
2000-57420 |
Claims
What is claimed is:
1. A heat sink for being mounted to a module board to which
semiconductor chips are attached and for dissipating or spreading
heat generated from the semiconductor chips, the heat sink
comprising: a heat sink base; and a coupling means for coupling the
heat sink base to the module board, the coupling means passing
through the heat sink base, wherein the coupling means includes
integrally formed upper and lower body portions, an orifice formed
at least through the lower body portion, and a flanged base formed
integral with the lower body portion, the flanged base fixing the
coupling means to the heat sink base, and wherein an outer
dimension of the upper body portion is smaller than an inner
dimension of the lower body portion.
2. A heat sink as claimed in claim 1, wherein a thermal interface
material made of a silicon rubber is attached to the heat sink
base.
3. A heat sink as claimed in claim 1, wherein the coupling means is
made of brass metal.
4. A heat sink as claimed in claim 3, wherein a thermal interface
material made of a silicon rubber is attached to the heat sink
base.
5. In combination, a heat sink for dissipating or spreading heat
generated from semiconductor chips, the heat sink comprising: a
heat sink base; and a coupling means for coupling the heat sink
base to the module board, the coupling means passing through the
heat sink base, wherein the coupling means includes integrally
formed upper and lower body portions, an orifice formed at least
through the lower body portion, and a flanged base formed integral
with the lower body portion, the flanged base fixing the coupling
means to the heat sink base, and wherein an outer dimension of the
upper body portion is smaller than an inner dimension of the lower
body portion; and b) a memory module board having holes formed
therethrough, wherein the coupling means passing through the holes
to couple the heat sink to the module board.
6. A combination as claimed in claim 5, wherein the semiconductor
chips are mounted only on one side of the module board.
7. A combination as claimed in claim 6, wherein the coupling means
is made of brass metal.
8. A combination as claimed in claim 6, wherein a thermal interface
material made of a silicon rubber is attached to the heat sink.
9. A combination as claimed in claim 5, wherein the semiconductor
chips are mounted on both sides of the module board.
10. A combination as claimed in claim 9, wherein the coupling means
is made of brass metal.
11. A combination as claimed in claim 9, wherein a thermal
interface material made of a silicon rubber is attached to the heat
sink.
12. A method for manufacturing a memory module, comprising:
preparing individual module boards with memory devices; preparing
lower and upper heat sinks, wherein the heat sinks each comprise a
heat sink base; and a coupling means for coupling the heat sink
base to the module board, the coupling means passing through the
heat sink base, wherein the coupling means includes integrally
formed upper and lower body portions, an orifice formed at least
through the lower body portion, and a flanged base formed integral
with the lower body portion, the flanged base fixing the coupling
means to the heat sink base, and wherein an outer dimension of the
upper body portion is smaller than an inner dimension of the lower
body portion, stacking the lower and upper heat sinks, wherein the
upper body portion of the coupling means of the lower heat sink is
inserted into the orifice formed through the lower body portion of
the coupling means of the upper heat sink; and coupling,
one-by-one, the heat sinks to the individual module boards using
the coupling means.
13. A method for stacking heat sinks for fabrication of a memory
module, comprising: preparing lower and upper heat sinks, the heat
sink comprising: a heat sink base; and a coupling means for
coupling the heat sink base to the module board, the coupling means
passing through the heat sink base, wherein the coupling means
includes upper and lower body portions, a shoulder joining the
lower and upper body portions and tapering therebetween, an orifice
formed at least through the lower body portion, and a flanged base
formed integral with the lower body portion, the flanged base
fixing the coupling means to the heat sink base, and wherein an
outer dimension of the upper body portion is smaller than an inner
dimension of the lower body portion, stacking the upper heat sinks
over the lower heat sink, wherein the upper body portion of the
coupling means of the lower heat sink is inserted into the orifice
formed through the lower body portion of the coupling means of the
upper heat sink, and wherein the flanged base of the upper heat
sink rests on the shoulder of the lower heat sink.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates generally to semiconductor chip
assembly technology, and more particularly, to a heat sink for a
memory module and a method of manufacturing the memory module with
the heat sink.
[0003] 2. Description of Related Art
[0004] In general, memory module devices have advantages in that
more than two semiconductor memory chips are mounted onto a single
circuit board to increase memory capacity. The memory modules also
overcome many inconveniences associated with mounting several
individual memory chips to the circuit board. In addition, the
utility of obsolete memory chips can be enhanced through the memory
module. Manufacturers employing surface mount technology for
producing the memory module commonly use an array of printed
circuit boards where several identical boards are continuously
connected.
[0005] As the operational speed of individual semiconductor chips
mounted on the board increases, more and more heat is produced from
the chips and hence it is important to effectively dissipate the
heat. In particular, Rambus DRAMs operating at even higher speed
than normal DRAMs require special concern in dissipating the heat.
For example, 64M Rambus DRAMs using a printed circuit board have
maximum operating power of 2.0W to 2.1W. Thus, the thermal problem
is an inevitable aspect of the device. To solve the thermal
problem, a heat sink can be connected to the memory module. A
conventional heat sink has a Thermal Interface Material (TIM)
attached to one side of the heat sink, and is fastened to the
memory module. The TIM is made of silicon rubber having good
thermal conductivity to transfer heat generated from the chips to
the heat sink.
[0006] In coupling the heat sink to the memory module, a fastener
such as a push pin or bolt is generally used. However, when the
heat sink is coupled to the memory module by the push pin or by the
bolt, the coupling strength of the heat sink and the memory module
is weak and the reliability of the module device is poor, while
memory module manufacturers and end users such as a set maker can
easily disassemble or remove the heat sink from the memory
module.
[0007] Further, due to the structural nature of push pins and
bolts, it is difficult for the heat sink producer to supply heat
sinks coupled to the fastener in advance. In addition, even when
the heat sinks coupled to the fastener are supplied to the memory
module manufacturer, it is difficult to stack vertically and load
individual heat sinks. Also, it is difficult to develop automatic
production appliances for coupling the heat sink to the memory
module.
[0008] On the other hand, according to current practices of memory
module manufacturers, memory modules are assembled onto an array of
printed circuit boards, dummy portions of the array are removed,
and electrical functions of the memory modules are tested. However,
in this process, it is difficult to couple the heat sink to the
memory module. In addition, it is difficult to develop an automatic
appliance for automatically coupling the heat sink and the memory
module.
SUMMARY OF THE INVENTION
[0009] It is an object of this invention to provide memory modules
having a structure such that the heat sinks are easily coupled to
the memory modules, and a manufacturing method thereof.
[0010] It is another object of this invention to provide heat sinks
having a structure adapted to the automatic production of memory
modules coupled with heat sinks.
[0011] According to one aspect of this invention, a heat sink is
attached to a module board on which a plurality of semiconductor
chips are mounted, and dissipates or spreads heat generated from
the chips. The heat sink includes a coupling means for coupling the
heat sink to the module board and a hole through which the coupling
means pierces. The coupling means includes integrally formed first
and second body portions, a flanged base integrally formed with the
second body portion. An orifice is formed at least through the
second body portion. The flanged base may be fixed to one side of
the module board and the first body is smaller than the second
body.
[0012] According to another aspect of this invention, a method for
manufacturing a memory module comprises: preparing an array of
printed circuit boards; preparing an individual module board by
cutting the array board; stacking a predetermined number of the
individual module boards; preparing a heat sink; coupling a
coupling means to the heat sink and attaching a thermal interface
material to the heat sink; stacking a plurality of heat sinks with
the coupling means and the thermal interface material; and coupling
the stacked individual module boards and the stacked heat sinks one
by one.
[0013] In one embodiment of this invention, a method for
manufacturing a memory module comprises: preparing an array of
module boards; providing individual module boards by cutting the
array board; stacking the individual module boards by a
predetermined number; preparing a first plurality of heat sinks;
attaching thermal interface materials and installing coupling means
to the first plurality of heat sinks; stacking the first plurality
of heat sinks; preparing a second plurality of heat sinks;
attaching thermal interface materials to the second plurality of
heat sinks; stacking the second plurality of heat sinks; and
coupling, one-by-one, the first and second plurality of heat sinks
to the individual module boards by using the coupling means.
[0014] In accordance with one aspect of the present invention, a
heat sink for being mounted to a module board to which
semiconductor chips are attached and for dissipating or spreading
heat generated from the semiconductor chips is disclosed. The heat
sink comprises a heat sink base; and a coupling means for coupling
the heat sink base to the module board. The coupling means passes
through the heat sink base. The coupling means includes integrally
formed upper and lower body portions, an orifice formed at least
through the lower body portion, and a flanged base formed integral
with the lower body portion, the flanged base fixing the coupling
means to the heat sink base. An outer dimension of the upper body
portion is smaller than an inner dimension of the lower body
portion.
[0015] In accordance with another aspect of the present invention,
a method for stacking heat sinks for fabrication of a memory module
is disclosed. The method comprises preparing lower and upper heat
sinks, the heat sink comprising:
[0016] a heat sink base; and
[0017] a coupling means for coupling the heat sink base to the
module board, the coupling means passing through the heat sink
base,
[0018] wherein the coupling means includes upper and lower body
portions, a shoulder joining the lower and upper body portions and
tapering therebetween, an orifice formed at least through the lower
body portion, and a flanged base formed integral with the lower
body portion, the flanged base fixing the coupling means to the
heat sink base, and
[0019] wherein an outer dimension of the upper body portion is
smaller than an inner dimension of the lower body portion. The
method further includes stacking the upper heat sinks over the
lower heat sink. The upper body portion of the coupling means of
the lower heat sink is inserted into the orifice formed through the
lower body portion of the coupling means of the upper heat sink,
and the flanged base of the upper heat sink rests on the shoulder
of the lower heat sink.
[0020] These and other features, and advantages, will be more
clearly understood from the following detailed description taken in
conjunction with the accompanying drawings. It is important to
point out that the illustrations may not necessarily be drawn to
scale, and that there may be other embodiments of this invention
that are not specifically illustrated.
BRIEF DESCRIPTION OF THE INVENTION
[0021] FIGS. 1a and 1b are a front view and a back view of a heat
sink with a coupling means.
[0022] FIG. 2 is a perspective view of a coupling means according
to an embodiment of the present invention.
[0023] FIG. 3a shows a plurality of heat sinks stacked
vertically.
[0024] FIG. 3b is a partially enlarged view of FIG. 3a .
[0025] FIG. 4 is a perspective view showing a coupling relationship
between a heat sink and a module board according to one embodiment
of the present invention.
[0026] FIG. 5 illustrates the process flow of memory
module-producing method according to one embodiment of the present
invention.
[0027] FIG. 6 is a perspective view showing a coupling relationship
between heat sinks and a module board according to another
embodiment of the present invention.
[0028] FIG. 7 illustrates the process flow of memory
module-producing process according to another embodiment of the
present invention.
[0029] FIG. 8 is a schematic block diagram of an automatic
apparatus suitable for use in manufacturing a memory module
device.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0030] FIGS. 1a and 1b show a heat sink with a coupling means
according to the present invention.
[0031] The heat sink 10 has in general a rectangular shape and four
coupling holes 12a, 12b, 12c and 12d perforating the heat sink. The
shape of the heat sink 10 and the number and position of the
coupling holes are not necessarily limited to the structure shown
in the drawings and depend on the module board to which the heat
sink is to be coupled. The heat sink 10 is made of metal with high
thermal conductivity such as aluminum. Coupling means 20 are
coupled to each of the coupling holes 12.
[0032] The inside wall of the heat sink (i.e., the side facing the
memory module) is attached to a Thermal Interface Material (TIM) 15
as shown in FIG. 1b. The TIM 15 is made of a silicon rubber that
exhibits high thermal conductivity and conveys heat generated from
semiconductor chips mounted on the module board to the heat sink.
The TIM 15 is double-sided or one-sided adhesive.
[0033] FIG. 2 shows a preferred embodiment of coupling means of the
present invention. The coupling means 20 shown is preferably an
eyelet. The eyelet coupling means 20 is preferably made of brass
metal or C2680 metal having improved elongation characteristics and
tensile strength. The heat sink is subjected to a punching process
when mounted on the module board. If the coupling means 20 is made
of a metal such as aluminum having poor tensile strength and
percentage of elongation, debris produced due to friction between
the eyelet and a punch pin (not shown) deteriorates the coupling
strength. The eyelet coupling means 20 may be plated with tin,
tin-lead or nickel metal.
[0034] The coupling means 20 includes a clinched head 22, a first
body 24 and a second body 26. An orifice or an opening 18 is formed
to extend from the head 22 to the end of first body 24. A diameter
of the first body 24 is preferably smaller than that of the second
body 26. That is, the orifice 18 is smaller inside the first body
than inside the second body. The reason for making different the
dimensions of the first and the second bodies 24 and 26 of the
orifice 18 is to apply the coupling means to automatic equipment
for producing memory module devices by stacking a number of heat
sinks.
[0035] The diameter D1 of the first body 24 and the diameter D2 of
the second body 26 are suitably configured or modified for easily
inserting the heat sink into a module board by automatic equipment
in consideration of the size and the thickness of the memory module
coupled with the heat sink. Further, the length L1 of the first
body 24 and the length L2 of the second body are so selected that
the coupling means 20 is not collapsed when the stacked heat sinks
are fixed in the automatic equipment.
[0036] FIG. 3a shows a number of heat sinks stacked vertically. As
explained above, since the diameter D1 of the first body 24 is
smaller than the diameter D2 of the second body 26, in the stacked
structure, the first body of the coupling means coupled to a lower
heat sink, as shown in FIG. 3b, is inserted into the orifice
penetrating the second body of the coupling means coupled to an
upper heat sink. As a result, a plurality of heat sinks are stacked
stably as shown in FIG. 3a . If heat sinks having a coupling means
of identical body dimensions are to be vertically stacked, the
stacking process is difficult and the stacked structure is
unstable. Further, the stacked structure occupies increased
space.
[0037] However, with the present invention, if memory module
manufacturers are supplied with a predetermined number (e.g.,
twenty) of heat sinks, it is easy to apply the heat sink to an
automatic appliance.
[0038] FIG. 4 is a perspective view showing the coupling
relationship between a heat sink 10 and a memory module 30. In this
embodiment, the heat sink 10 is coupled to a Rambus Inline Memory
Module (RIMM) having memory semiconductor chips 32 attached to only
one side of a memory module board 30. Through holes 34 to which
each of coupling means 20 penetrate are formed in the module board
30, and a tab 35 for electrically connecting the module 30 to
external devices such as a mother board or a main board is formed.
End tip of the coupling means 20 penetrating the through holes 34
and protruding from the board are clinched and fixed to the board
by a punch process.
[0039] FIG. 5 shows the process flow for manufacturing the RIMM
module having memory chips mounted on only one side as shown in
FIG. 4.
[0040] In step 40, an array of module boards is prepared. The array
board is formed of several identical individual boards connected to
each other. Each of the individual boards is connected by a dummy
portion. By cutting the dummy portion, individual boards are
prepared in step 41. The prepared individual boards are vertically
stacked by a predetermined number in step 42.
[0041] In step 43, heat sinks are prepared. Four eyelets and a TIM
are attached to each heat sink in step 44. The heat sinks, with
attached eyelets and TIM, are then stacked vertically in step
45.
[0042] In step 46, each of the stacked heat sinks is coupled or
locked to each of the stacked module boards one by one. Visual
inspection is performed on the module device coupled with the heat
sink in step 47.
[0043] It is preferable to include the preparation step of the
individual module board when producing the memory module device,
because when a heat sink is coupled to the array of the module
board, mechanical pressure, e.g., punching pressure applied to the
coupling means may cause a torsion in the array board and damage
memory chips mounted to the board. In addition, when the heat sinks
are coupled to the array board and the individual boards are
prepared by cutting the array board, physical shock and vibration
occurring in those processes may cause cracking in joints, e.g.,
solder joints between the chips and the board. Moreover, particles
or dust produced during the cutting process remain on the board and
cause failures of the chips and modules. It is, therefore,
preferable to prepare the individual module boards and then couple
the heat sinks to the individual module boards.
[0044] In addition, electrical testing and visual inspection are
performed after the heat sinks are coupled to the module boards,
for the reason that the semiconductor chips are exposed and
vulnerable to damage when the chips are not covered by heat sinks
coupled to the board. Accordingly, an electrical testing and a
visual inspection are performed on the individual module devices.
When the individual devices are determined defective in the
electrical test, the reason for failure is analyzed. When defects
are found in the visual inspection, the defective devices are
subject to a reworking process. For the reworking process, the heat
sinks have to be removed from the module board and consequently the
coupling means need to be removed.
[0045] FIG. 6 is a perspective view for showing the coupling
relationship between heat sinks and a memory module according to
another embodiment of the present invention. In this embodiment,
RIMM module devices having semiconductor memory chips 62 are
mounted on both sides of a module board 60. Two heat sinks 10 and
50 are coupled to the module board 60 for the two-sided chips 62.
However, coupling means are locked to only the first heat sink 10.
To the second heat sink 50 are formed through holes 52 to which the
coupling means 20 are inserted. Other through holes 64 are also
formed in the module board 60. The module board 60 includes a tab
65 for electrically connecting the module board to an external
device.
[0046] FIG. 7 shows the process flow for producing a memory module
device having heat sinks coupled to both sides of the board.
[0047] Referring to FIG. 7, an array board is prepared in step 71,
and individual module boards are prepared by cutting the array
board in step 72. The prepared individual boards are stacked in
step 73.
[0048] In step 74, a first heat sink is prepared, and in step 75,
eyelets and a TIM are attached to the first heat sink. A
predetermined number of the first heat sinks, each of which is
coupled with the eyelet coupling means are stacked vertically in
step 76. In step 77, a second heat sink is prepared, and in step
78, a TIM is attached to the second heat sink. A predetermined
number of the second heat sinks with attached TIM are stacked
vertically in step 79.
[0049] The individual module board and the first and second heat
sinks are coupled together by the eyelet coupling means in step 80.
Then, an electrical test and a visual inspection are performed in
step 82.
[0050] FIG. 8 is a schematic block diagram of an exemplary
automatic appliance suitable for use in the memory module
manufacturing process of the present invention. An apparatus 90 for
manufacturing the memory module comprises a heat sink loader 91, a
module board loader 92, a heat sink carrier 93, a module board
carrier 94, a coupling part 95, an inspection part 96 and an
unloader 97.
[0051] The heat sink loader 91 includes a loading portion (not
shown) for vertically stacking to a predetermined height both heat
sinks without eyelets and heat sinks having eyelets coupled. The
module board loader 92 loads a predetermined number of modules
contained in a tray. The heat sink carrier 93 conveys, one-by-one,
heat sinks contained in the heat sink loader 91. The module board
carrier 94 conveys, one-by-one, module boards contained in the
module board loader 92. The coupling part 95 aligns the heat sinks
conveyed by the carrier 93 and the module boards transferred by the
carrier 94, and couples or locks the heat sink to the board by
using eyelet coupling means coupled to the heat sink. The
inspection part 96 checks the coupling state of the heat sink and
the board. The unloader 97 sorts the module devices according the
result of the inspection, and loads the sorted devices to
corresponding trays.
[0052] As described herein, according to the present invention, a
heat sink can be easily coupled to a module board, and it is
possible to apply a memory module with a heat sink to an automatic
appliance.
[0053] In the drawings and specification, there have been disclosed
typical preferred embodiments of this invention and, although
specific terms are employed, they are used in a generic and
descriptive sense only and not for purposes of limitation, the
scope of this invention being set forth in the following
claims.
* * * * *