JP3028673B2 - Heat sink for multi-chip module and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink for a multichip module, that is, a large scale integrated circuit (LS).
The present invention relates to a heat sink used for cooling a multi-chip module (MCM) in which a plurality of chips generating heat such as I) are brought close to each other and sealed together, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In response to a rapid increase in the amount of information processing and a demand for high-speed information processing, high integration of electronic components represented by ICs and LSIs by miniaturizing electronic circuits in a chip has been progressing. The use of a multi-chip module (MCM) for encapsulating a plurality of highly integrated chips in close proximity and collectively is rapidly increasing.

FIG. 1A shows a schematic perspective view of such a multi-chip module before sealing, FIG. 1B shows a cross-sectional view after sealing, and a side view showing a state where a heat sink is attached. As shown in FIG. 1C, a plurality of LSI chips 2 are mounted on a multilayer ceramic wiring substrate (MLS) 1 and hermetically sealed with a cap 3 to form a multi-chip module package 5. The input / output of the electric signal is performed by the pin 4.

Since a plurality of highly integrated chips are mounted on each chip, the heat generation density and the heat generation amount are the same as those of a conventional single IC.
Since the number of chips has increased dramatically compared to that of packages and the like, it is necessary to cool the entire package so that each chip is kept at an allowable temperature or lower in order to secure a circuit operation speed and improve reliability.
Therefore, in order to efficiently dissipate the heat generated from the chip to the outside, a structure in which a heat sink 6 is attached to the multi-chip module package 5 as shown in FIG. (Hakuhodo Shuppan, '87, edited by The Japan Society of Mechanical Engineers, cooling technology for electronic equipment, p.30-32). The heat sink 6 is placed in the working fluid, and forcibly cools it.

In this case, the cap 3 and the chip 2 are made of a material having the same linear expansion coefficient, and the chip 2 die-bonded 7 to the cap 3 transfers the generated heat from the cap 3 to the heat sink 6. It is cooled by being removed through heat conduction and through heat transfer from the heat sink 6 to the working fluid.

Conventionally, as this cooling method, forced quenching in which air is forcedly supplied as a working fluid to a heat sink has been frequently used because the structure of the cooling device is simple and easy.
Also, as a heat sink shape used for the forced air cooling, a channel fin having a parallel plate array of radiating fins 12 (hereinafter referred to as a radiating plate) on a bottom plate 11 as shown in FIG. A pin fin in which pin-shaped fins 13 (hereinafter, referred to as heat radiation pins) are arranged on the bottom plate 11 is representative.

In order to cope with a large amount of heat generated by the multi-chip module by cooling using these conventional heat sinks, it is necessary to improve the heat radiation capacity by increasing the heat radiation area of the heat sink and increasing the flow rate of air passing through the fins. is there.

However, in order to increase the heat dissipation area of the heat sink, the fin pitch, without changing the bottom plate area,
It is necessary to reduce the fin interval, and it is difficult to obtain a necessary heat radiation area by a conventional heat sink manufacturing method such as extrusion, cutting, die casting, or the like. In addition, if an attempt is made to increase the flow rate of air passing through the fins of the heat sink, a large-output blower having a sufficient blowing capacity is required while compensating for a large pressure loss generated in the heat sink flow path, which causes a problem of space and noise.

As described above, it is very difficult to cool the multi-chip module below the allowable temperature by forced air cooling using a conventional heat sink.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of insufficient cooling capacity due to the restriction of the heat radiation area and to reduce the pressure loss in the heat sink flow path in cooling a multi-chip module having a large heat generation density and heat value. To
An object of the present invention is to provide a heat sink having a heat radiation area much larger than conventional channel fins and pin fins having the same bottom area and a relatively small pressure loss in a flow path, and a method of manufacturing the same.

More specifically, an object of the present invention is intended to be used under forced air cooling, and is several times to several tens times as large as conventional channel fins and pin fins used under the same forced air cooling. An object of the present invention is to provide a heat sink having extremely high heat dissipation performance and a manufacturing method thereof.

[0012]

Means for Solving the Problems The present inventors have made various studies to solve the above-mentioned problems. As a result, the heat generated from each chip can be radiated by providing a corresponding heat sink. It has been found that the cooling efficiency is reduced as a whole because the flow of the working fluid for forced cooling is hindered by the large number of collected fluids and sufficient heat transfer is not performed.

Therefore, the present inventors provide the heat radiation fins in a large number of groups, arrange the groups in a staggered manner, and preferably also arrange the heat radiation fins constituting them as a whole. Alternatively, the present inventors have found that the ventilation resistance can be reduced as much as possible by arranging them in a staggered manner, and the present invention has been completed.

Here, the gist of the present invention resides in that a plurality of parallel plate-shaped radiation fins or pin-shaped radiation fins integrated with the bottom plate are formed on the bottom plate, and a plurality of the radiation fins formed on the same bottom plate. The radiating fin is formed integrally with the bottom plate.
With multiple aligned or staggered protrusions
Form parallel groove rows with predetermined depth and width on the protruding part of the material
To achieve multiple heat dissipation
A heat sink for a multi-chip module, wherein fins are divided into a plurality of groups, and a plurality of sets of fin groups are arranged at predetermined intervals or arranged in a staggered or even random manner. According to a preferred embodiment of the present invention,
The radiation fins constituting the plurality of fin groups may also be aligned or staggered as a whole.

In another aspect, the invention is directed to a workpiece having a plurality of aligned or staggered projections integral with a bottom plate formed, for example, by plastic working or machining. A fin comprising a plurality of parallel plate-shaped heat-dissipating fins, which is formed by a plurality of parallel plate-shaped heat-dissipating fins, which are desirably detoured around the non-projected portion by a wire saw having a wire row wound so that only a required wire comes into contact with the workpiece. This is a method of manufacturing a heat sink for a multi-chip module in which a plurality of groups are formed, and further, in the case of a pin-shaped heat radiation fin, then, the parallel plate heat radiation fin of such a semi-finished product is referred to as this parallel plate fin. Forming radiation fins by grinding with a wire saw having a wire row wound so that only a required wire is in contact with the workpiece in a direction orthogonal to the workpiece Pin-shaped having a rectangular cross section, characterized in bets
A method for manufacturing a heat sink for a multi-chip module including the heat radiating fins .

[0016]

Next, the present invention will be described in more detail with reference to the accompanying drawings. FIG. 3 (a) is a perspective view showing an outline of a heat sink composed of a radiator plate type fin group according to the present invention, and (b) and (c) are partial enlarged views of the fin group and each heat radiation fin. FIG.

In FIG. 3, the radiating fin groups 30 are arranged in a line, and the radiating fins 32 of the parallel plates constituting the radiating fin groups 30 themselves are also arranged in a line. These intervals can be set as appropriate. FIG. 4 (a) is a perspective view showing an outline of a heat sink of a heat radiation pin type according to the present invention, and FIGS. 4 (b) and 4 (c) are partially enlarged views of the fin group and each heat radiation fin.

In FIG. 4, the fin groups 40 are arranged in a line, and the pin-shaped heat radiation fins 42 constituting the fin groups 40 are also arranged in a line. These intervals can be set appropriately as in the case of FIG. In each of the heat sinks of FIGS. 3 and 4, the bottom plates 34, 44 and the fin groups 30, 40 have an integral structure as described with reference to FIG.

The thickness t and gap g of the radiating fin 32 of the radiating plate type, and the cross-sectional dimensions t ₁ × t ₂ and the gaps g ₁ and g ₂ of the radiating pin of the radiating fin 42 of the radiating pin type are respectively conventional. The fin thickness of the radiator plate type radiator fins and the fin size of the pin type radiator fins are extremely small, and the heat radiation area can be significantly increased. Because
This is because the development of the wire sawing method has enabled industrial fine processing for the first time.

According to the structure of the present invention, adjacent fin groups are separated from each other by a distance of C ₁ , C ₂ , and each fin group 30 is formed in a flow path 36, 38, 46, 48 formed thereby. , 40, since the air that has taken heat from the heat sink flows into the heat sink, pressure loss due to friction in the flow path of the heat sink as a whole is considerably reduced. FIG. 5 is a perspective view of a workpiece as a starting material for manufacturing the heat sink of the present invention.

The work piece has a bottom plate 50 having the same dimensions (W × L × T) as a heat sink of a heat sink type or a pin type, and a rectangular horizontal cross section having a plane dimension (a ₁ × a ₂ ) integrally formed therewith. The projection 52 has a plurality of protrusions 52 having a height H and is made of a material having a high thermal conductivity such as an aluminum alloy or a copper alloy. The distances C ₁ and C ₂ between the projections 52 are the same as the distances C ₁ and C ₂ between the fin groups described above.

The workpiece itself may be formed, for example, by cold forging a plate having a plane dimension W × L and a thickness greater than T and smaller than H, or a plate having a plane dimension W × L and a thickness T + H. It is formed by a method of cutting with a milling cutter or the like. Next, a method for manufacturing a heat sink according to the present invention will be described. 6A and 6B illustrate a method of manufacturing a radiator fin and a pin-type radiator fin. FIG. 6A is a schematic perspective view of a wire saw processing portion, and FIG. 6B is a front view thereof.

A wire 60, which is, for example, a piano wire, sent from a wire feeding device (not shown) from the left-hand direction in the drawing is wound around a groove roller 62 and wound to form a wire row 61 at a predetermined pitch and width. You. At this time, a wire row 61a that contacts the protrusion of the workpiece 64 and is involved in the processing.
Is wound around four groove rollers 62a, 62b, 62c and 62d, but the wire 61b which is not involved in the processing is provided with three groove rollers.
It is desirable that only non-protruding portions be detoured around only 62a, 62b and 62d in a triangular shape. This prevents the wire row of the non-working part from hitting the heat sink or the heat sink pin formed by vibrations, etc., causing it to fall down or cutting the bottom plate, and the abrasive grains and foreign matter in the working fluid are brought into between the groove roller and the wire. This is to prevent the occurrence of derailment and disconnection.

From this fact, it is apparent that the wire row which is not involved in the processing may be circulated only by the two groove rollers 62a and 62b. However, the bending of the wire is minimized as much as possible, and the force applied to the groove roller is reduced. From the viewpoint of reducing as much as possible, it is preferable to make a round around the three groove rollers as described above.

The wire wound around the groove roller to form a wire row in this manner is wound rightward in the figure by a wire winding device (not shown). Four groove rollers 62a
, 62b, 62c and 62d are rotationally driven to move the wire array in one direction. The workpiece 64 mounted on the mounting table 63 on the traveling wire row and fixed so that the wire and two sides thereof are parallel to each other is pressed together with the mounting table by being raised, and between the wire row and the workpiece. By supplying a working fluid 66 containing abrasive grains from the nozzle 65, only the portion of the workpiece to which the wire row of projections is pressed by the grinding action of the abrasive grains is scraped off.

The radiating fins of the radiating plate type are formed by raising the mounting table by a predetermined radiating plate height H from a position where the workpiece starts to contact the wire row. On the other hand, in the same manner as described above, the pin-type radiating fins are formed by raising the mounting table by a predetermined radiating plate height H from a position where the workpiece starts to contact the wire row, thereby forming a parallel plate row-shaped fin. After forming a plurality of groups, the workpiece is temporarily separated from the wire row, and the workpiece is pressed against the wire row so that the fin longitudinal direction of the fin group and the wire row are orthogonal to each other, and the workpiece is ground in the same manner . A plurality of heat radiation pin groups are formed.

FIG. 7 shows this state.
The wire row 61a is arranged so as to be orthogonal to the heat radiating fin of the heat radiating plate type formed in advance on 64, and then the workpiece is pressed against the wire row. As described above, the pin-type radiating fins may be manufactured by grinding twice.
As shown in (a) and (b) in a plan view and a side view, respectively, two wire rows 61a, 61a are set in advance in two directions orthogonal to each other, and a projection is formed into a heat radiation pin group by a single grinding. Can be performed by the same principle. At this time, the two orthogonal wire rows 61a cannot be set at the same height, so the groove depth to be cut is slightly different in the two orthogonal directions, but the difference is at most about the wire diameter, so there is no practical problem.

In the above description, the case where the fin groups are aligned is taken as an example, but the same applies to the case where the fin groups are arranged in a staggered or at random manner.
Next, the present invention will be described more specifically with reference to examples.

[0029]

[Embodiment 1] The dimensions shown in FIG. 5 are L = W = 60.
_{mm, a 1 = 11.42mm, a} 2 = 10.00mm, C 1 = 3.28mm, C 2 = 4.
A workpiece made of pure aluminum having a size of 0 mm, T = 1.0 mm, and H = 14.0 mm was manufactured by cold forging. The work material prepared in this manner is fixed to a mounting table 63 as shown in FIGS. 6 (a) and 6 (b), and a piano wire having a diameter of 0.4 mm is brought into contact with the projection of the work material at a pitch of 0.7 mm. 6 at four positions, and five at three positions not in contact with the protrusions of the workpiece, FIG.
Pressing the wire row 61a stretched as in (a), applying a processing liquid in which # 600GC abrasive grains are mixed with lapping oil by using the nozzle 65 while running this wire row at a speed of 400 m / min. 63 was raised at a rate of 0.3 mm per minute, pressed against the wire row 61a, and ground to a depth of 14mm.

The dimensions shown in FIG. 3 are t = 0.22 mm, g = 0.
A fin group composed of 17 heat-dissipating fins in the form of 48 mm parallel plates was manufactured in 4 × 4 = 16 sets on a bottom plate to produce a heat sink. The obtained heat sink 90 is shown in FIGS. 9 (a) and 9 (b).
A wind tunnel experiment was conducted with a structure in which cooling air flows into the parallel plate fin group in a direction perpendicular to the bottom plate surface by attaching to the heater 91 and the rectifier 92 as shown in When changed, calorific value 50-80W,
Under the condition of a flow velocity of 1.2 m / sec, it exhibited a revolutionary cooling performance with a pressure loss of about 800 Pa and a thermal resistance of about 0.6 K / W.

[Embodiment 2] The dimensions shown in FIG.
_{100mm, a 1 = a 2 =} 11.42mm, C 1 = C 2 = 4.68mm, T = 1.0 m
A workpiece made of an aluminum alloy 2024 with m and H = 20.0 mm was manufactured by cutting. The work material prepared in this manner is fixed to a mounting table 63 as shown in FIGS. 6 (a) and 6 (b), and a piano wire having a diameter of 0.4 mm is formed at a pitch of 0.7 mm.
At positions where they do not come into contact with the projections, 16 and 6 rows, and at positions where they do not come into contact with the projections of the workpiece, 7 and 5 rows are pressed against a wire row 61a stretched as shown in FIG. 40 per minute
While traveling at a speed of 0 m, a working liquid in which # 600GC abrasive grains were mixed with lapping oil was applied, the mounting table 63 was raised at a speed of 0.35 mm / min, pressed against the wire row and ground to a depth of 20 mm.

Thus, the dimension shown in FIG.
A heat sink semi-finished product in which 6 × 6 = 36 sets of fin groups of radiating fins in the form of a parallel plate composed of 17 radiating plates of 0.22 mm and g = 0.48 mm were arranged on the bottom plate. Thereafter, the mounting table 63 is lowered to separate the semi-finished product from the wire row, and the semi-finished product is rotated by 90 ° on the mounting table so that the heat radiating plate formed as shown in FIG. Pressing against the same wire row as used for molding, applying a working liquid in which # 600GC abrasive grains were mixed with lapping oil while running this wire row at a speed of 400 m / min, and setting the mounting table at 0.95 The wire was raised at a speed of mm, pressed against the wire row, and ground to a depth of 20 mm.

Thus, the dimensions shown in FIG. 4 are t ₁ = t ₂ =
A heat sink was obtained in which 6 × 6 = 36 sets of fins composed of 17 × 17 = 289 radiating pins of 0.22 mm and g ₁ = g ₂ = 0.48 mm were arranged on a bottom plate. The obtained heat sink is shown in FIG.
(B) A wind tunnel experiment was performed with a structure in which cooling air flows into the parallel plate fins in a direction perpendicular to the bottom plate surface by installing the heater 103 and the rectifier 104 as shown in (b).
When the calorific value and air flow rate were changed at 20 ° C, the calorific value was 50.
Pressure drop of about 900 P under conditions of ~ 100 W and flow velocity of 1.0 m / sec
a, It showed a revolutionary cooling performance with a thermal resistance of about 0.4K / W.

[0034]

The heat sink comprising the heat dissipating fins according to the present invention is capable of significantly increasing the heat dissipating area per the same bottom area as compared with the conventional heat sink comprising the channel fins and the pin fins, thereby significantly improving the cooling capacity. At the same time, the increase in pressure loss due to flow path friction is kept low, so that multichip modules with extremely large heat generation and heat density can be cooled to the allowable temperature by forced air cooling using a conventional small blower. It is something that makes it easy. In addition, the heat sink including the radiation fins according to the present invention can be applied not only to the cooling of the multi-chip module but also to the cooling of the single-chip module.

[Brief description of the drawings]

1A, 1B, and 1C are a schematic perspective view, a cross-sectional view after sealing, and a side view of a multi-chip module, respectively.

FIGS. 2 (a) and 2 (b) are perspective views of a conventional heat radiating plate type and a pin type radiating fin for forced air cooling, respectively.

FIGS. 3A, 3B and 3C are a schematic perspective view, a partially enlarged view, and a part of a heat sink composed of a heat sink of a heat sink type for a multi-chip module according to the present invention. FIG.

FIGS. 4 (a), (b) and (c) are a schematic perspective view, a partially enlarged view, and a part of a heat sink composed of a pin-type radiating fin for a multi-chip module of the present invention. It is an enlarged view.

FIG. 5 is a schematic perspective view of a workpiece used for forming the heat sink of the present invention by the manufacturing method of the present invention.

FIGS. 6 (a) and 6 (b) are a perspective view and a side view, respectively, for explaining a method for manufacturing a wire saw and a heat sink according to the present invention.

FIG. 7 is an explanatory diagram of a positional relationship between a wire row of a processed portion and a workpiece.

FIGS. 8 (a) and 8 (b) are a plan view and a side view, respectively, for explaining a positional relationship between a wire row of a processed portion and a workpiece.

FIGS. 9 (a) and 9 (b) are a plan view and a side view, respectively, for explaining the cooling method of the embodiment.

FIGS. 10A and 10B are a plan view and a side view, respectively, for explaining a cooling method according to an embodiment.

Claims (6)

(57) [Claims] 1. A plurality of parallel plate-shaped radiating fins formed integrally with the bottom plate on a bottom plate, and the plurality of radiating fins formed on the same bottom plate are formed integrally with the bottom plate. It is constituted by forming a parallel groove row having a predetermined depth and width on a projection portion of a material having a plurality of aligned or staggered projections, thereby dividing a plurality of heat radiation fins into a plurality of groups, A heat sink for a multi-chip module, wherein fin groups formed as a set are arranged or staggered at predetermined intervals. 2. A plurality of pin-shaped radiating fins formed integrally with the bottom plate on the bottom plate, and a plurality of the radiating fins formed on the same bottom plate are formed integrally with the bottom plate. A parallel groove row having a predetermined depth and width is formed on a projection portion of a material having projections arranged or arranged in a staggered pattern to form a semi-finished product, and then a parallel wall row between the parallel groove rows of the semi-finished product is formed into a predetermined shape. A multi-chip comprising a plurality of heat dissipating fins divided into a plurality of groups, and a plurality of sets of fin groups arranged at predetermined intervals or arranged in a staggered manner. Heat sink for module. 3. A wire row stretched over a bottom plate at a projection portion of a material having a plurality of aligned or staggered projections formed integrally with the bottom plate at the same pitch as the fins. Then, the wire row and the material are pressed in a state in which a working fluid containing abrasive grains is interposed between the wire row and the raw material, and a predetermined depth and a predetermined width and width are formed on the projecting portion of the raw material by the grinding action of the abrasive grains. 2. The method for manufacturing a heat sink for a multi-chip module according to claim 1, wherein a parallel groove row having the following is formed. 4. A wire row stretched over a bottom plate at a projection portion of a material having a plurality of aligned or staggered projections formed integrally with the bottom plate at the same pitch as the fins. In the meantime, the wire row and the material are pressed in a state where a working fluid containing abrasive grains is interposed between the wire row and the material, and a parallel groove row having a predetermined depth and width is formed by the grinding action of the abrasive grains. The semi-finished product is formed into a semi-finished product, and then the parallel flat fins of the semi-finished product are run on a wire row stretched at the same pitch as the fin pitch in a direction orthogonal to the parallel flat fins, and the parallel grooves of the semi-finished product are formed in the wire row. A pin having a rectangular cross section, wherein the wire row and the semi-finished product are pressed so that the rows intersect, and the parallel wall rows between the parallel groove rows of the semi-finished product are cut to a predetermined depth by the grinding action of the abrasive grains. Heat dissipation 3. The method for manufacturing a heat sink for a multi-chip module according to claim 2, further comprising: 5. When a projection portion of a material having a plurality of aligned or staggered projections formed integrally with the bottom plate on the bottom plate is subjected to abrasive processing by a wire saw, the wire is bypassed by a non-projection portion. The method for manufacturing a heat sink for a multi-chip module according to claim 3, wherein 6. When a projection portion of a material having a plurality of aligned or staggered projections formed integrally with the bottom plate on the bottom plate is subjected to abrasive processing by a wire saw, the wire is bypassed by a non-projection portion. 5. The method for manufacturing a heat sink for a multi-chip module according to claim 4, wherein: