JP2002314013A - Heat radiating material and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [Problem] To provide a fin having good boiling efficiency for a cooling liquid on a heat radiating layer side of a heat radiating material and to have a lower thermal expansion coefficient on a heat receiving layer side of the heat radiating material so that the semiconductor insulating plate and the heat radiating material Provided is a more compact heat radiating material having a small warp after joining and a method of manufacturing the heat radiating material at a low cost. A heat dissipating material is constituted by a porous sintered body obtained by adding a binder to a mixture of a metal powder having good heat conductivity and an inorganic material powder having a lower coefficient of thermal expansion than the metal. A heat-receiving layer that absorbs heat from the heating element; and a heat-dissipating layer that is integrated with the heat-receiving layer and emits heat from the heat-receiving layer to the outside. The fins 4 of the ratio were provided. The inter-fin groove 11 is formed in a concave arc shape and has a low porosity. The heat receiving layer 2 is made of a copper composite material having a low coefficient of thermal expansion, and a heating element is bonded through a metal 47 for bonding an insulating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipating material used for a cooling method using a liquid and a method for manufacturing the same, and more particularly, to a heat dissipating material having good boiling heat conductivity and small heat distortion, and an efficient method for manufacturing the same. And a method for producing the same.

[0002]

2. Description of the Related Art As the capacity and speed of semiconductors increase, the amount of heat generated by semiconductor chips tends to increase. For this reason, in order to prevent the deterioration of the characteristics of the semiconductor element and the shortening of the life of the semiconductor element due to heat generation, it is necessary to provide a heat radiating member to suppress the temperature rise in the semiconductor element and its vicinity. Copper is generally used as a heat dissipating member for LSIs because copper has a large thermal conductivity of 393 W / (m · K) and is inexpensive. On the other hand, semiconductor elements for power and energy conversion and control having various on / off functions generate a particularly large amount of heat, so that a material having a thermal expansion coefficient close to that of silicon as a semiconductor chip (molybdenum) is used as a heat dissipation material. , Tungsten) is used.

Further, the use of a composite material having a single copper oxide concentration (for example, a copper oxide concentration of about 50%) having a thermal expansion coefficient and a thermal conductivity substantially intermediate between copper and molybdenum / tungsten has been attempted.
An attempt is made to improve the heat radiation effect and prevent warpage due to thermal expansion.

FIG. 5 shows a state of use when a sintered body is used as a heat dissipating material. Conventional heat dissipating material 36 having the same pore diameter
When the heat-dissipating material (the density of the sintered material is almost uniform in order to make the strength of the heat-dissipating material uniform) is attached to a water-cooled cooler or the like (the heat-dissipating material heat dissipating layer is on the upper side and the heat receiving layer is lower), the pore diameter is smaller. Because they are equal
The cooling fluid 40 on the heat radiation side boils mainly from the fin portion 52 (where the temperature difference between the cooling fluid and the surface is larger) close to the heat receiving layer 2 and is released as bubbles 23. As a result, the fins 51
The surroundings are covered with the bubbles 23 and the coolant is sucked in the inter-fin portion 52 closer to the bubble surface than the intrusion of the coolant 40 from the end surfaces of the fins 51, so that the fins 51 are not much used for the boiling action. Therefore, the boiling performance is considered to decrease.

As shown in FIG. 6, when a conventional heat radiating material 36 is attached to a water-cooled cooler or the like (the heat radiating material radiating layer is on the lower side,
The heat receiving layer is on the upper side. ), The bubbles 23 released out of the sintered body by boiling stay immediately below the heat radiation layer (immediately below the fin portions 11), and form a heat insulator having a large thermal resistance, so that the heat transfer performance is reduced. At this time, the boiling performance is recovered by slightly tilting the heat radiating member 36 from the horizontal level and flowing out or evacuating the stagnant bubbles 23a. However, in this case as well, the inter-fin portion 52 of the conventional heat dissipating material 36 is covered with the air bubbles 23, so that it is difficult to suck the coolant 40 through the inter-fin portion 52. The cooling liquid 40 sucked from the fins 51 rises mainly while being heated by the capillary action inside the fins, and the generated bubbles are released as bubbles 23 in the inter-fin portion 52 by buoyancy. However, in such a case, since the density of the sintered material of the conventional heat dissipating material 36 is substantially uniform, the suction of the cooling liquid from the fins 51 is not easily performed. Has a problem. When the heat radiating layer is on the upper side and the heat receiving layer is on the lower side,

As for the heat radiation member, the grooved lower punch 19 shown in FIG. 8 is made of metal powder (put into the powder filling portion 44).
Is formed by press molding.

Further, in order to improve the heat dissipation performance of the heat dissipation material,
When an efficient fin is provided on the heat radiation side, processing with a milling machine or a lathe is required.

[0008]

However, conventional heat dissipating materials
According to copper used for the thermal expansion coefficient is 17 × 10
^-6/ K, heat dissipation material for semiconductor devices that generates a large amount of heat
There was a problem that it could not be used. Also, molybdenum
And tungsten have a low coefficient of thermal expansion and a good thermal conductivity.
Although excellent, there is a problem that it is expensive.

Furthermore, when a single copper oxide composite material is used, after a high-temperature bonding with a semiconductor insulating plate (having a low thermal expansion coefficient), the thermal expansion coefficient between the semiconductor insulating plate and the low thermal expansion radiating material is reduced. There has been a problem that warpage occurs due to the difference, which makes it difficult to use. Further, the performance of the heat radiating material on the heat radiating layer side was not so high, and the heat radiating material was likely to be large in size.

In the case where a sintered material is used and the heat radiating layer is on the upper side and the heat receiving layer is on the lower side, the cooling liquid is sucked in between the fins closer to the bubble surface than the cooling liquid enters from the fins. Therefore, there has been a problem that the fins are not used much for the boiling action and the boiling performance is reduced. In addition, when the heat radiating layer is on the lower side and the heat receiving layer is on the upper side, the cooling liquid is not easily sucked between the fins, so that the conventional heat radiating material has a problem in boiling performance.

When the conventional press-formed product is taken out from the grooved lower punch, the fin is pressed against the grooved lower punch. There was a problem of separation at the root.

Further, press molding requires a high pressure to be applied to the material and requires time. In addition, machining with a milling machine or a lathe has a problem that the manufacturing cost is increased.

According to the present invention, a fin having good boiling efficiency is provided for the cooling liquid on the heat radiating layer side, while the heat receiving layer side of the heat radiating layer has a lower coefficient of thermal expansion so that the semiconductor insulating plate and the heat radiating layer can be joined together. An object of the present invention is to provide a more compact heat radiating material having a small warpage and a method of manufacturing the heat radiating material at a low cost.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and a heat radiating material for radiating heat generated by a heating element such as a semiconductor element is provided with a metal powder having good heat conductivity. A first sintered body of a mixture of a powder of an inorganic material having a lower coefficient of thermal expansion than the metal powder, a heat receiving layer for absorbing heat generated by the heating element, a metal powder having good heat transfer and a lower heat than the metal powder; It is composed of a second sintered body of a mixture with a powder of an inorganic material having an expansion coefficient, and has a finned heat radiation layer integrated with the heat receiving layer. The heat radiation layer has a fin having a high porosity. The sintered body was made of a sintered body having a low porosity between the fins, and the binder concentration of the powder was set to 0.5 to 10% to form a heat radiation layer. Further, the fins of the heat radiation layer are formed in a concave arc shape. Therefore, the coolant tends to boil on the heat radiation layer side, and the coolant is sucked between the fins, thereby improving the conduction efficiency. In addition, the flow of the cooling liquid and the evaporating gas is smooth, and the increase in thermal resistance and corrosion due to the stagnation of the cooling liquid and the evaporating gas can be avoided.

The heat radiation layer has a fin apex angle of 0 to 90 degrees and a ratio of fin height to bottom wall thickness of 0.5 to 3. The heat dissipation performance and fin strength are taken into account.

The good heat conductive metal is copper, and the inorganic material is
It is characterized by being cuprous oxide (Cu ₂ O). A copper alloy having a cuprous oxide (Cu ₂ O) concentration of 70% or less in the heat receiving layer, and a copper or cuprous oxide (Cu
₂ O) It is characterized by comprising a copper composite material comprising a copper alloy having a concentration of 0% or more. Since the heat receiving layer side of the heat dissipating material is a low thermal expansion material, warpage after bonding with the semiconductor insulating plate can be reduced.

On the heat receiving side surface of the heat receiving layer, tin, lead, bismuth,
It is characterized by being coated or plated with zinc, aluminum, copper or nickel. Since the metal on the surface on the heat receiving side of the heat receiving layer is covered or plated, it is easy to bond with the insulating material.

A binder of a powder is added to a mixture of a metal powder having good heat conductivity and a powder of an inorganic material having a lower coefficient of thermal expansion than the metal powder, and the mixture is pressed by a mold and heated to form a sintered body. A method for manufacturing a heat radiating material comprising a heat radiating material by a sintered body is characterized in that sintering is performed with the binder concentration of the powder at the time of forming the heat radiating layer being 0.5 to 10%. In addition, the heat radiation layer is characterized in that a release agent is applied to a fin molding die in advance and press-molded. Therefore, machining for fin molding after sintering can be omitted,
Significant reduction in manufacturing cost can be achieved.

The mixture of the metal powders is characterized in that it has a groove shape for transferring fins and is press-formed by a fin-forming mold having a convex end formed at the tip of the mold. The fin is press-formed by a mold divided for each fin. It is characterized in that a fin forming die for press-forming the metal powder is connected to a holder or a fin forming die supporting die by a pin, a screw or the like. Therefore, it is possible to shorten the time for setting the mold and to improve the reliability.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a heat radiating material and a method of manufacturing the same according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a heat dissipation material according to the present invention. In the heat radiating material 1, the fins 4 having a high porosity are formed on the heat receiving layer 2, and the fin portions 11 have a low porosity. The heat receiving layer 2 has a smooth surface, and the heat receiving side surface of the heat receiving layer 2 is coated with a thin metal 47 for bonding an insulating material with plating or metal foil. However, the thickness of the metal 47 is exaggerated and greatly illustrated.

Since the space 11 between the fins is formed in a concave arc shape, the flow of the coolant and the bubbles flows more smoothly, and the increase in the thermal resistance or corrosion of the coolant due to the stagnation of the coolant and the bubbles is prevented. Can be avoided.

Further, since the insulating material bonding metal 47 is coated or plated on the heat receiving side surface of the heat receiving layer 2 after sintering, the adhesiveness with the insulator is improved, and the density of the heat radiating material 2 (voidless) is improved. ) Can be improved, and the leakage of the coolant on the heat receiving layer side of the heat dissipating material and the decrease in thermal conductivity can be prevented.

As shown in FIG. 2, the external shape is a rectangular plate shape, and the fins are arranged on the upper surface. FIG. 3 is FIG.
FIG. 3 is a cross-sectional view taken along line AA of FIG. However, it is drawn in a simplified manner. Reference numeral 6 denotes the height of the fin, and 7 denotes the bottom wall thickness, and indicates the height of the heat radiation layer 3 and the height of the heat receiving layer 2 excluding the height 6 of the fin 4 from the heat radiation layer 3. 8 is the pitch between the fins. 9 is a work width and 10 is a work length.

The heat dissipating body 1 comprising the heat dissipating layer 3 and the heat receiving layer 2 including the fins 4 is press-formed after adding a binder to a good heat conductive metal powder and a powder of an inorganic material having a lower coefficient of thermal expansion than the above-mentioned metal. It is obtained by preheating and sintering after eliminating the binder by preheating. Therefore, it is characterized in that the inorganic material particles are dispersed in the good heat conductive metal and cavities are generated by the disappearance of the binder. The diameter of the inorganic material particles dispersed in the metal is 200 μm or less, preferably 60 μm or less. This is because a low-thermal-expansion radiator can be obtained only when the inorganic material particles are dispersed in the metal.

In addition to copper, gold, silver, and aluminum having high thermal conductivity can be used as the good heat conductive metal used for the heat radiating material according to the present invention. Further, as an inorganic material, the thermal expansion coefficient in a temperature range from room temperature to 300 ° C. is 5 × 10 ⁻⁶ /
K or less of tin oxide, zinc oxide, lead oxide, nickel oxide, aluminum oxide (Al ₂ O ₃ ) and the like can also be used. As the powder binder, aluminum stearate, zinc stearate or the like having a melting temperature lower than the sintering temperature can be used.

The heat dissipating material of the present invention comprises cuprous oxide (Cu
_{It is} made of a copper (Cu) alloy containing 0 to 70% by volume of 2O). This copper alloy has a thermal expansion coefficient from room temperature to 300 ° C. of 7 to 18 × 10 ⁻⁶ / K and a thermal conductivity of 80 to
390 W / m · K. When the amount of cuprous oxide is 0% by volume (copper alone), the coefficient of thermal expansion is 18 × 10 ^−6.
/ K or more, and when the amount of cuprous oxide is 70% by volume or more, the thermal conductivity is 80 W / m · K or less, but on average, a low thermal expansion heat radiating material having a thermal conductivity of 230 W / m · K is used. Becomes possible (

See Table 1).

[Table 1]

As shown in FIG. 1, the heat radiating material of the present invention has different heights in the pressing direction (the pressing direction when pressing a mixture of a metal, an inorganic material, and a binder). Is constant, the porosity of the fins becomes large because the compression ratio of the powder at the time of press molding is smaller in the high fins than in the portion between the low fins. Further, the binder is mixed and formed into a low-concentration mixed powder of inorganic material (cupric oxide) (see FIG. 10), and when sintered, the binder disappears in the sintering process, and the inorganic material (oxidized oxide (Copper) The voids of the low concentration composite are combined to form continuous cavities.

The state of use of the heat radiating material thus manufactured will be described. FIG. 4 is a view for explaining a use state of the heat radiator of the present invention (when the heat radiator 1 is attached to a water-cooled cooler or the like), and is an explanatory view in a case where a heating element is located below the figure.
FIG. 5 is a diagram for explaining a usage state of a conventional heat radiating material, and is an explanatory diagram in a case where a heating element is located below the drawing.

As shown in FIG. 4, when the heat radiating material of the present invention is used, the cooling liquid 40 (downward solid line arrow) first boils from the fin 4 having a large porosity, that is, a large pore diameter. Air bubbles 23 (upward broken arrows) are emitted outside the fins.

Since the cooling liquid is boiled by the fins 4 and the cooling liquid is released outside the fins, the continuous pores inside the fins 4 and between the fins 11 have a negative pressure, and mainly have a water (liquid) pressure. The cooling liquid is sucked through the pores of the large fin space 11. The sucked coolant 40 is heated while passing through the continuous pores in the fins 4 and the generated bubbles 23
Reaches the surface of the fin 4 by buoyancy and is released as bubbles 23 out of the fin. The above cooling cycle is repeatedly performed. In FIG. 4, 22 indicates the flow direction of the coolant, 47 indicates a metal for bonding an insulator, 20 indicates an insulating plate, 21 indicates a heating element such as a semiconductor, and 39 indicates a heat transfer direction.

In the conventional example shown in FIG. 5, as described above, the cooling liquid 40 boils mainly from the inter-fin portion 11 where the temperature difference between the cooling liquid and the surface is large. The fins 51 are covered and become less utilized for the boiling action. Note that the same reference numerals as those in FIG. 4 have the same meanings.

As described above, when the conventional heat radiating material having the same pore diameter is used, the fins 51 are hardly used for the boiling action, the boiling performance is reduced, and the heat transport ability is reduced. According to the heat dissipating material according to the present invention, the continuous holes formed in the fins and between the fins, the boiling of the cooling liquid,
The heat transfer capacity is greatly improved because it is greatly involved in release and suction.

Further, since the heat radiating material 1 of the present invention has a higher porosity than a smooth surface, the heat radiating heat transfer area is greatly increased, and the heat transfer performance is improved. Further, since the flow 22 of the cooling liquid 40 is stirred by the fins 4, the heat transfer performance (radiation) of the heat radiating material 1 further increases.

FIG. 7 is a view for explaining a use state of the heat radiating material of the present invention, and is an explanatory view in a case where a heating element is located above the figure.
FIG. 6 is a diagram for explaining a use state of a conventional heat radiating material, and is an explanatory diagram in a case where a heating element is located above the drawing.

As shown in FIGS. 6 and 7, when the heat dissipating material 1 of the present invention is mounted on a water-cooled cooler or the like (the heat dissipating layer is on the lower side and the heat receiving layer is on the upper side), it is baked by boiling. Bubbles 23 released outside the unit are located immediately below the heat radiation layer (between the fins 1).
1 immediately below) to form a heat insulator having a large thermal resistance, so that the heat transfer performance is reduced. At that time, heat sink 1
Boiling performance is restored when the air bubbles 23a that are slightly tilted and stagnated are washed away or degassed. However, also in that case, since the inter-fin portion 11 of the heat radiating material 1 of the present invention is covered with the air bubbles 23, it becomes difficult to inhale the cooling liquid 40 in the inter-fin portion 11. The cooling liquid 40 sucked from the fins 4 rises mainly while being heated by the capillary action inside the fins, and the generated bubbles are released as bubbles 23 in the inter-fin portion 11 by buoyancy. However, even in such a case, the radiator 1 of the present invention has a higher porosity of the fins 4 than the conventional radiator 36, and the pores are continuous. The heat radiation material 1 of the present invention has improved boiling performance as compared with the conventional heat radiation material 36 because the inhalation of the heat is easily performed.

By the way, the fins can be formed by machining such as a milling machine or a lathe, but the production cost is greatly increased. In order to reduce the manufacturing cost, it is desirable to manufacture fins by press molding.

In the mold (grooved core) 14 used in the present invention shown in FIG.
4, the continuous fin having a low fin height and a large fin apex angle can be obtained. In addition,
The fin apex angle 5 is shown in FIG. 14, and the fin height is shown in FIG. Reference numeral 17 denotes a connector rod, which is used to connect the fin-forming mold (core with a groove) 14 and the lower punch 16 to shorten the time for setting the mold or to improve the reliability. .

However, when a continuous fin having a high fin height and a small fin apex angle is used, the contact area between the fin and the mold is increased, and the adhesive force between the fin and the mold 14 is increased. Further, since the contact area per fin width is increased, the strength of the fin is reduced. As a result, when removing the press-formed product 41 from the grooved core mold 14, the fins are restrained by the grooved core mold 14, and the fins are separated at the fin roots, or the fins are separated from the grooved core mold 14. The groove surface damages and makes it difficult to remove the slim continuous fin.

Therefore, if the mold release material 30 is applied to the grooved core mold 14 before powder filling (see FIG. 10), the adhesive force between the grooved core mold 14 and the compact 41 is reduced. As shown in FIG. 20, the adhesive force of the compact to the mold is reduced to about 30% as compared with the case where the release material 30 is not applied.

Further, by adding a binder to the mixed powder and improving the strength of the fin, the fin apex angle is 0 to 90.
It is possible to obtain a slim continuous fin having a high heat transfer performance in which the ratio of the degree and the fin height to the bottom wall thickness is 0.5 to 3. The fin strength increases at a binder concentration of 0.5 to 10%,
A slim and porous radiator can be manufactured. However, the higher the binder concentration, the voids (voids) in the sintered body
However, the strength and heat transfer performance of the fins are reduced, so that the binder concentration is 0.5 to 1
0% (see FIG. 21). The bottom wall thickness is shown in FIG.

When the fin height is constant, when the ratio between the fin height and the bottom wall thickness is increased, the bottom wall thickness is reduced, the thermal resistance is reduced, and the heat radiation performance is improved. In order to maintain the strength of the fin bottom portion, and as the fin height increases, the heat transfer efficiency of the fin decreases, it is desirable that the fin height be as low as possible. Therefore, the ratio between the fin height and the bottom thickness is set to 0.5 to 3. .

Since the radius is provided on the bottom side of the fin, the flow of the coolant and the bubbles flows more smoothly, and an increase in the thermal resistance or corrosion of the coolant due to the stagnation of the coolant and the bubbles can be avoided.

Further, since the surface of the heat receiving layer of the heat radiating material of the present invention is coated or plated with a metal for bonding the insulator after sintering, the adhesion to the insulator is improved and the density of the heat receiving layer of the heat radiating material (voidless) is improved. ) Is improved, and the leakage of the cooling liquid on the heat receiving layer side of the heat radiating material and the decrease in thermal conductivity can be prevented.

[0044]

FIG. 9, FIG. 10 and FIG. 11 show a method of manufacturing a heat radiating material according to the present invention. As the raw material powder, an electrolytic copper powder having an average particle diameter of 10 μm and a cupric oxide (CuO) powder having a particle diameter of 50 μm or less were used. After sintering the electrolytic copper powder and the cupric oxide powder

After mixing so as to have the ratio shown in Table 1, powder binder 31 is further mixed and mixed at 0.5 to 10% by weight, and the mixture is stirred and mixed in a dry ball mill containing steel balls for 7 hours or more.

The grooved core mold 14 is inserted into the powder filling portion 44 formed by the die 27 and the lower punch 16, and the release material 3
0 is applied to the grooved core mold 14, and the above mixed powder 29 obtained by adding a powder binder to electrolytic copper powder and cupric oxide powder.
Fill. After filling the mixed powder, the upper surface of the powder filling is scraped off with a skeper to make the powder filling amount for forming the compact 41 constant.

Next, the upper punch 26 is pressurized by the press presser 25 and pressed to a predetermined thickness. Then press rod 2
5, the die support 28 is removed, and the guide 35 is set on the die 27 surface. The press push rod 25 is lowered, and the die 27 is pushed down to a position where the lower part of the grooved core mold 14 can be seen.

Next, the press push rod 25 is raised and the guide 3
5 is removed, the upper punch 26 is removed from the powder body 41, and the powder body 41 is removed from the grooved core mold 14.

The concentration of cuprous oxide in the heat dissipating material was adjusted to
When the cuprous oxide concentration of the heat receiving layer 2 is high, first, the electrolytic copper powder 45 having a small particle diameter including the binder 31 (the particle diameter of the binder 31 is larger than the copper powder and smaller than the cupric oxide powder) Is filled into the heat radiation layer side (the mold 14 side of the present invention), and then a mixed powder 46 having a high concentration of cupric oxide is filled up to the powder filling portion 44, and then the powder is filled with heat. On the side (upper punch side), the concentration of cupric oxide in the mixed powder 29 is increased. Next, pressurization is performed by a press, and thereafter, the press-formed product 41 is preheated at 200 to 300 degrees to remove the binder.

The sintering temperature depends on the cupric oxide content.
The temperature is varied between 50 and 1000 ° C. and the sintering temperature is maintained for 3 hours. Thereafter, the sintered body 42 is sufficiently cooled. A sintered body having high porosity in the fins and low porosity between the fins is obtained.
The metal 47 for bonding the insulating material was plated (thickness: 200 μm).
m) or less, the sintering is performed on the surface side of the heat receiving layer.
On the other hand, a metal 47 for bonding an insulating material is coated (thickness: 200 μm).
In the following case), after applying vibration to the space generated by the above-mentioned vibration (the space surrounded by the die on the filling powder surface), inserting a metal foil (thickness: 200 μm or less), and then pressing with a press,
When sintered, it joins with the composite.

[0050]

Table 1 shows the T of the simple composite at room temperature to 300 ° C.
The reference data of the coefficient of thermal expansion of the copper composite material measured using a MA (Therma1 Mechanica1 Analysis) device and the thermal conductivity obtained by a laser flash method are shown.

In addition, since the heat dissipating material 1 of the present invention actually changes the concentration of cuprous oxide (inorganic material) continuously, the low concentration of cuprous oxide (inorganic material) composite layer 49 and the cuprous oxide (inorganic material) change. No boundary of the inorganic material) high concentration composite layer 50 is seen, but the cuprous oxide (inorganic material) low concentration composite layer 49 and the cuprous oxide (inorganic material) have a small amount of cuprous oxide (inorganic material) as a heat dissipating material. The boundary of the high-concentration composite layer 50 with a lot of) is schematically indicated by a broken line. That is, the boundary between the heat receiving layer 2 and the heat radiation layer 3 is represented by a broken line.

Another embodiment is shown in FIGS. FIG. 12 shows a second embodiment of the heat dissipating material, in which the heat receiving layer 2 is in contact with the bottom of the rectangular fin 4a. The metal for bonding the insulating material is omitted. FIG. 13 shows a third embodiment of the heat dissipating material, in which the heat receiving layer 2 and the fin 4b are not in direct contact.

FIG. 14 shows a fourth embodiment of the heat dissipating material, in which the fin tip 13a is formed in a needle shape and the surface area per fin volume is increased, so that the release of air bubbles from the fin 4c is facilitated. Further, the boiling performance can be further improved. FIG. 15 shows a fifth embodiment of the heat dissipating material, in which fins 4d and 4e having different shapes are alternately arranged.
By arranging in this way, the heat radiation material 1d which increases the stirring of the cooling fluid and further improves the heat transfer performance (radiation) is provided. These are manufactured according to the application.

Note that the fin apex angle 5 (see FIG. 14) is the angle at the intersection of the trend lines on both sides of the fin. Usually, the fin apex angle 5 when considered as a trapezoidal fin is nearly 0 degrees.

FIGS. 16 and 17 show the second and third embodiments of the fin forming mold. Cores for fin molding 18, 18
Since a is divided for each fin, it is possible to easily obtain a heat dissipating material provided with fins having different shapes, for example, as shown in FIG. Reference numeral 15 shown in FIG. 16 is a holder, and reference numeral 17 shown in FIG. 17 is a connector rod,
The fin-forming cores 18 and 18a are connected to the lower punch 16 and are used for shortening the time for setting a mold or improving reliability.

FIG. 18 shows a sixth embodiment of a heat dissipating material, which is a heat dissipating material 1e in which fins 4f are provided with recesses 43 at regular intervals at the tips of the fins by means of a mold having projections formed in the grooves of the fin forming mold. The case where the flow of the cooling liquid is changed to change the heat radiation performance of the heat radiation layer 3 is shown.

FIG. 19 is a view showing a seventh embodiment of the heat dissipating material.
FIG. 4 shows a plan view of the heat radiating member 1f in the case where the radiator is provided. The mounting surface 37 is made smooth and a mounting hole 38 is provided. Reference numeral 9 indicates a work width, and reference numeral 10 indicates a work length. 8
Is the pitch of the fins.

FIG. 20 is a view showing an eighth embodiment of the heat dissipating material, wherein the heat dissipating fins are fins 4 having different fin heights 6 and 6a.
h and fins 4i are alternately arranged in parallel in the width direction. The heat radiating material 1g reduces the pressure loss of the fluid, changes the flow of the coolant in a complicated manner, enhances the stirring effect of the fluid, and improves the heat radiation performance. It is intended. Reference numerals 5a and 5b indicate fin apex angles.

[0059]

As described above, according to the present invention, the heat-receiving layer has a low thermal expansion metal composite comprising a metal and an inorganic material.
The heat radiation layer is formed by a grooved core mold or a fin molding core so that the fin having a high porosity and the porosity between the fins becomes a low porosity portion. The following effects can be obtained by coating or plating with lead, bismuth, aluminum, copper, nickel).

(1) Since the radiating layer side is composed of high porosity fins and low porosity fins, a cycle of boiling of the coolant on the fin side and suction or preheating of the coolant on the fins is formed. Therefore, heat transfer efficiency is improved, and a heat dissipating material having good heat conductivity can be obtained.

(2) Since the heat exchange form on the heat radiation layer side mainly changes from the conventional convection heat transfer to the boiling heat transfer, the heat radiation performance can be greatly improved. Therefore, the heat radiation material can be made compact (the fin height can be reduced). And reduce the thickness of the heat dissipating material).

(3) Since the space between the fins of the heat radiating layer 3 is formed in a concave arc shape, the flow of the cooling liquid and the bubbles is improved, and the heat radiating performance and the corrosion resistance of the heat radiating material are improved.

(4) On the other hand, since the surface of the heat receiving layer is coated or plated with a metal for bonding an insulator (tin, lead, pismuth, aluminum, copper, nickel), the density of the heat radiating material on the heat receiving layer side is reduced. And heat conductivity and corrosion resistance are improved.

(5) Since the fins and the fins are formed during press molding, machining of the fins after sintering can be omitted, and the production cost can be greatly reduced.

(6) By using a fin having a low coefficient of thermal expansion on the heat receiving layer side and a high thermal conductivity on the heat radiation side, it is possible to reduce the warpage of the heat radiator after bonding with a semiconductor insulating material using solder or the like.

(7) When molding the fins and the fins, the fins have an apex angle of 0 to 0 by using a release agent and a binder.
A high-performance heat dissipating material having a fin height of 90 degrees and a ratio of fin height to bottom wall thickness of 0.5 to 3 can be generated.

(8) By variously changing the groove shape of the fin forming die, heat radiating materials having various fin shapes can be generated.

(9) By using the connector rod, the core mold for fin molding and the lower punch are connected, so that the time for setting the mold or the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view of a heat dissipating material according to a first embodiment of the present invention.

FIG. 2 is a plan view of a heat dissipating material according to a first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a heat dissipating material according to a first embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a use state (under a heating side) of the radiator according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a usage state (below a heating side) of a conventional heat dissipation material.

FIG. 6 is a cross-sectional view illustrating a usage state (on a heating side) of a conventional heat dissipation material.

FIG. 7 is a view showing a usage state of a heat radiator according to the first embodiment of the present invention;
FIG. 4 is a cross-sectional view illustrating (on the heating side).

FIG. 8 is a cross-sectional view of a conventional fin molding die.

FIG. 9 is a plan view of a fin forming die used in the first embodiment of the manufacturing method of the present invention.

FIG. 10 is a cross-sectional view illustrating press forming by a manufacturing method according to the present invention.

FIG. 11 is a cross-sectional view illustrating removal of a molded product after press molding by the manufacturing method according to the present invention.

FIG. 12 is a cross-sectional view of a heat dissipating material according to a second embodiment of the present invention.

FIG. 13 is a cross-sectional view of a heat radiator according to a third embodiment of the present invention.

FIG. 14 is a cross-sectional view of a heat radiator according to a fourth embodiment of the present invention.

FIG. 15 is a sectional view of a heat dissipating material according to a fifth embodiment of the present invention.

FIG. 16 is a sectional view of a fin forming die used in a second embodiment of the manufacturing method of the present invention.

FIG. 17 is a sectional view of a fin forming die used in a third embodiment of the manufacturing method of the present invention.

FIG. 18 is an external view illustrating a radiator according to a sixth embodiment of the present invention.

FIG. 19 is a cross-sectional view of a heat radiator according to a seventh embodiment of the present invention.

FIG. 20 is a sectional view of a heat dissipating material according to an eighth embodiment of the present invention.

FIG. 21 is a diagram illustrating the influence of a binder when manufacturing a press-formed product.

FIG. 22 is a diagram showing a drawing force under various conditions when a press-formed product is taken out.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 heat radiating material 2 heat receiving layer 3 heat radiating layer 4 fin 5 fin apex angle 6 fin height 7 fin bottom thickness 8 fin pitch 9 work width 10 work length 11 fin portion 13 fin tip 14 mold used in the present invention (Groove core) 15 Holder 16 Lower punch 17 Connector pin (screw) 18 Die (fin molding core) used in the present invention 19 Groove lower punch 20 Insulating plate 21 Semiconductor (heating element) 22 Coolant Flow direction 23 Bubbles 24 Press direction 25 Press push rod 26 Upper punch 27 Die 28 Die support 29 Mixed powder 30 Release material 31 Powder binder 32 Press base 33 Extrusion direction 34 Die advancing direction 35 Guide 36 Conventional radiator 37 Cooler Mounting surface 38 Mounting hole 39 Heat transfer direction 40 Coolant 41 Press-formed product 42 Sintered body 4 3 Fin recess 44 Powder filling part 45 Low concentration mixed powder of inorganic material (copper oxide) 46 High concentration mixed powder of inorganic material (cupric oxide) 47 Metal for bonding insulating material (plating layer or metal foil) 49 Inorganic material Low-concentration composite material (cuprous oxide low-concentration copper composite material) 50 Inorganic material high-concentration composite material (cuprous oxide high-concentration copper composite material) 51 Conventional heat dissipating fins 52 Conventional heat dissipating material grooves

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K018 AA04 AB01 AC01 BA02 BA11 BD10 CA13 HA05 JA03 JA14 KA23 KA32 5F036 AA01 BA07 BA24 BB05 BD01 BD11

Claims (13)

[Claims] 1. A heat dissipating material for dissipating heat generated by a heating element such as a semiconductor element, comprising: a first sintered body of a mixture of a good heat conductive metal powder and a powder of an inorganic material having a lower coefficient of thermal expansion than the metal powder. Composed,
A heat receiving layer that absorbs heat generated by the heating element, and a second sintered body of a mixture of a metal powder having good heat transfer and an inorganic material powder having a lower coefficient of thermal expansion than the metal powder;
A heat dissipating material comprising a heat dissipating layer with fins integrated with the heat receiving layer. 2. The heat dissipating material according to claim 1, wherein the heat dissipating layer has a fin formed of a sintered body having a high porosity and an inter-fin portion formed of a sintered body having a low porosity. 3. The heat radiation layer according to claim 1, wherein the heat radiation layer is formed of a sintered body obtained by sintering a press-formed product having a binder concentration of powder of 0.5 to 10%. A heat dissipating material according to claim 1. 4. The fin according to claim 1, wherein the fin has a fin apex angle of 0 to 90 degrees and a ratio of the fin height to the bottom wall thickness of 0.5 to 3. The heat dissipating material described in. 5. The heat radiating material according to claim 1, wherein the good heat conductive metal is copper, and the inorganic material is cuprous oxide (Cu ₂ O). 6. The heat receiving layer is made of cuprous oxide (Cu ₂ O).
Concentration of 70% or less of the copper alloy, the heat dissipation layer, claims, characterized in that the copper or cuprous oxide (Cu ₂ O) concentration was composed of copper composite material consisting of at least 0% of the copper alloy 1-3
The heat dissipating material according to any one of the above. 7. The heat dissipating material according to claim 1, wherein the heat dissipating layer has a portion between the fins formed in a concave arc shape. 8. The heat receiving layer has tin on its heat receiving side surface.
The lead, bismuth, zinc, aluminum, copper or nickel is coated or plated.
The heat radiating material according to any one of items 4 and 6. 9. A mixture of a metal powder having good heat conductivity and a powder of an inorganic material having a lower coefficient of thermal expansion than the metal powder, a binder of the powder is added, and the mixture is press-molded by a mold and heated to form a sintered body. In the method for manufacturing a heat radiating material comprising the sintered body, the heat radiating layer is sintered by setting the binder concentration of the powder at the time of press molding to 0.5 to 10%. Manufacturing method. 10. The method for manufacturing a heat radiating material according to claim 9, wherein said heat radiating layer is formed by applying a release agent in advance to a fin forming die and press forming. 11. The fin-forming mixture having a groove shape for transferring fins and being press-formed by a fin-forming die having a die end formed in a convex arc shape. The method for producing a heat radiating material according to any one of claims 10 to 10. 12. The fin according to claim 9, wherein the fin is press-formed by a mold divided for each fin.
12. The method for producing a heat dissipating material according to any one of items 11 to 12. 13. The heat dissipating material according to claim 9, wherein the fin forming die is connected to a holder or a fin forming die supporting die by a pin, a screw, or the like. Production method.