JP2006298687A - Heatsink material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heatsink material with which the adherability between a porous sintered compact composed of carbon or graphite and a metal is improved and a carbide layer is easily formed in the interface between the carbon or the graphite and the metal, and which has thermal conductivity, a coefficient of thermal expansion and strength sufficient as the heatsink material. <P>SOLUTION: The heatsink material 10 is obtained by infiltrating a metal 14 into a porous sintered compact 12 obtained by networking by firing carbon or graphite. An element for improving the adherability in the interface with the porous sintered compact 12 is added to the metal 14 to be infiltrated into the porous sintered compact 12. Especially, in this embodiment, Fe (iron) is used as the element to be added for improving the wettability of the interface. It is preferable that Fe is added in an amount of 0.01-4 wt.% and Si is added to the metal 14 for improving the flowing property of a melt. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat sink material for forming a heat sink that efficiently dissipates heat generated from, for example, an IC chip, and a manufacturing method thereof.

  The present invention relates to a heat sink material for forming a heat sink that efficiently dissipates heat generated from, for example, an IC chip, and a manufacturing method thereof.

  In general, heat is a great enemy for IC chips, and the internal temperature must not exceed the maximum allowable junction temperature. In addition, since power consumption per operation area is large in a semiconductor device such as a power transistor or a semiconductor rectifier element, the amount of heat generated cannot be released only by the amount of heat released from the case (package) or lead of the semiconductor device. Internal temperature may rise and cause thermal destruction.

  This phenomenon is the same in an IC chip equipped with a CPU. The amount of heat generated during operation increases as the clock frequency increases, and thermal design considering heat dissipation has become an important matter.

  In the thermal design considering the prevention of the thermal breakdown, element design and mounting design are performed in consideration of fixing a heat sink having a large heat radiation area to the case (package) of the IC chip.

  As the material for the heat sink, a metal material such as copper or aluminum having a good thermal conductivity is generally used.

  And as a conventional heat sink material, the ceramic base material which contains SiC as a main component contains metal Cu in the ratio of 20-40 vol% (refer patent document 1), and the powder sintering porous which consists of inorganic substances A body impregnated with 5 to 30 wt% of Cu (see Patent Document 2) has been proposed.

  Since the heat sink material according to Patent Document 1 is powder molding in which a green compact of SiC and metal Cu is molded to produce a heat sink, the thermal expansion coefficient and thermal conductivity are theoretical values to the last. There is a problem that the balance between the thermal expansion coefficient and the thermal conductivity required for an actual electronic component or the like cannot be obtained.

  In Patent Document 2, the ratio of Cu impregnated in a powder sintered porous body made of an inorganic substance is low, and there is a possibility that a limit may arise in increasing the thermal conductivity.

  Accordingly, the applicant of the present invention can easily obtain a heat sink material capable of obtaining characteristics suitable for the balance between the thermal expansion coefficient and the thermal conductivity required for an actual electronic component (including a semiconductor device), and the like. A method of manufacturing a heat sink material that can be manufactured and that can improve the productivity of a high-quality heat sink material has been proposed (see Patent Document 3).

Japanese Patent Laid-Open No. 8-279579 JP 59-228742 A Japanese Patent Laid-Open No. 2001-339022

  The present invention can further improve the heat sink material shown in Patent Document 3 to improve the adhesion between the porous sintered body made of carbon or graphite and the metal, and the interface between the carbon or graphite and the metal. It is an object of the present invention to provide a heat sink material having a thermal conductivity, a thermal expansion coefficient, and a strength as a heat sink material, and a method for manufacturing the same.

  The heat sink material according to the present invention includes carbon or graphite and a metal, and is configured by impregnating the metal into a porous sintered body obtained by firing and networking the carbon or graphite. The average of the three axial directions or the thermal conductivity of any axial direction is 180 W / mK or more and the coefficient of thermal expansion is 1 ppm / ° C. to 10 ppm / ° C., and the metal includes carbon or graphite. An element for improving adhesion at least at the interface is added.

  Thereby, the adhesiveness between the porous sintered body made of carbon or graphite and the metal can be improved. As the metal, at least one selected from Cu and Al can be adopted.

  And in the said structure, it is preferable that the said additional element for the adhesive improvement at least of the said interface is Fe (iron). Fe is an element that easily dissolves in carbon or graphite, and has the effect of improving adhesion at the interface with carbon or graphite during impregnation. It also has the effect of improving the wettability at the interface with carbon or graphite.

  In this case, it is preferable that 0.01 to 4 wt% of Fe is added. If the added amount of Fe exceeds 4 wt%, there is a risk that a γ phase may be produced when alloying with a metal (for example, Cu), and the hot metal flowability may be reduced. It is because there exists a possibility that hot water flow property may fall similarly.

  Si is preferably added to the metal in order to improve the hot water flow. That is, in the above-mentioned Patent Document 3, Sn, P, Si, and Mg are described as elements that improve the flowability of molten metal, but Si is the only element that is easier to form as carbide than Fe at the interface melted by Fe. This is because it was proved to be.

  In this case, it is preferable that 0.1 to 12 wt% of Si is added. The effect starts to appear when the amount of Si is 0.1% or more. However, if it exceeds 12 wt%, the coefficient of thermal expansion increases, and there is a possibility that 10 ppm / ° C. obtained by networking cannot be satisfied.

  And the following synergistic effects can be acquired by adding Fe and Si to the said metal. That is, the addition of Fe improves adhesion at the interface with carbon or graphite, but the solid-liquid coexistence range is narrow in the range of 0.01 to 4 wt% which is effective as described above, and the hot water flowability is reduced. May be worse. Since Si is the only element that improves molten metal flow and is more easily formed as carbide than Fe at the interface melted by Fe, Si can improve molten metal flow.

  Therefore, adhesion by melting at the interface with carbon or graphite is improved by Fe, and carbide is easily formed by Si at the interface, so that the thermal conductivity, thermal expansion coefficient and mechanical strength necessary as a heat sink material are obtained. It is possible to obtain a heat sink material having both.

  The tensile strength of the porous sintered body after impregnating the metal is preferably 3.5 MPa or more. Tensile strength is affected by adhesion. Even at the same level of impregnation, the difference in adhesion is reflected in the mechanical strength. That is, the higher the adhesion of the metal to the porous sintered body, the higher the tensile strength and the higher the compressive strength proportionally. In this case, if the tensile strength is low, there is a risk of damage during handling during soldering or the like, and further there is a risk that the heat sink material cannot be screwed. Therefore, if the tensile strength is 4.5 MPa or more, screw tightening is easy, and if it is 3.5 MPa, handling during soldering and the like becomes easy.

  In addition, it is preferable that the closed porosity of the produced heat sink material is 12 vol% or less. Moreover, it is preferable to use the carbon or graphite having a thermal conductivity of 100 W / mK or more.

  The volume ratio of the carbon or graphite and the metal is 20 vol% to 95 vol% for the carbon or graphite, and the volume ratio of 80 vol% to 5 vol% for the metal, or the volume ratio of the carbon or graphite and the metal. However, the carbon or graphite is preferably in the range of 50 vol% to 95 vol%, and the metal is preferably in the range of 50 vol% to 5 vol%.

  A carbide layer is preferably formed on the surface of the carbon or graphite. In this case, the formation of the carbide layer is based on a reaction between at least the carbon or graphite and an additive element.

  Moreover, in the said structure, ratio of heat conductivity is 1: 5 or less in the direction which takes the minimum heat conductivity, and the direction which takes the maximum heat conductivity. Thereby, since the thermal conductivity has a characteristic that is almost isotropic, the heat diffusion is good and it is suitable for use as a heat sink. Further, it is not necessary to consider the installation direction one by one, which is advantageous in terms of mounting.

  The porosity of the porous sintered body is preferably 5 vol% to 50 vol%, and the average pore diameter is preferably 0.1 μm to 200 μm.

  Next, a method of manufacturing a heat sink material according to the present invention includes a firing step of producing a porous sintered body by firing and networking carbon or graphite, and a plurality of holes forming the porous sintered body. It is characterized by having a packaging step of wrapping in a heat insulating member and fixing with an iron fastening means, and an impregnation step of impregnating the porous sintered body with metal.

  As a result, the adhesion between the porous sintered body made of carbon or graphite and the metal can be improved, and a carbide layer can be easily formed at the interface between the carbon or graphite and the metal, and heat as a heat sink material can be obtained. A heat sink material having conductivity, coefficient of thermal expansion and strength can be obtained.

  The heat retaining member may include a mica sheet. A wire can be used as the fastening means.

  When a series of steps from at least the packaging step to the impregnation step is defined as one cycle, the porous sintered body is impregnated in the impregnation step in the immediately preceding cycle or in the previous cycle after two cycles. The metal that has not been used may be reused as the metal for impregnation. As a result, the material cost can be reduced, which is advantageous in reducing the product cost.

  It is preferable to stop the reuse when the metal reused as the metal for impregnation contains Fe exceeding 4 wt%.

  You may make it have the process of pre-heating the said porous sintered compact packaged at the said packaging process between the said packaging process and the said impregnation process. In this case, the metal is easily impregnated into the porous sintered body networked by this pre-heat treatment. The preheating temperature is preferably preheated to the same level as the impregnating metal.

  The impregnation step includes a step of accommodating the porous sintered body wrapped in the heat retaining member and fixed by the iron fastening means in a mold of a press machine, and the mold in the mold You may make it have the process of pouring a molten metal, and the process of impregnating the said molten metal in the said porous sintered compact by pushing down and pressing-in the said molten metal with the punch of the said press.

  Moreover, between the said baking process and the said packaging process, it has the process process which processes the said porous sintered compact produced at the said baking process, and produces a processed body, The said packaging process is at least 1 The two processed bodies may be wrapped with a heat retaining member and fixed with an iron fastening means.

  In the packaging process, when two or more of the processed bodies are wrapped with a heat retaining member and fixed with an iron fastening means, an object that is more easily impregnated with the metal than the processed bodies is interposed between the processed bodies. It is desirable to carry it between. In other words, porous sintered bodies such as mica sheets, ceramic paper, porous ceramics and honeycombs in which many holes are formed between the processed bodies so that the pressure during impregnation is close to hydrostatic pressure It is possible to impregnate two or more workpieces with the metal by sandwiching an object that is more easily impregnated. As a result, poor impregnation (unimpregnation or increased variation in the amount of impregnation) can be eliminated, and the pressure can be made uniform, so that damage to the workpiece and generation of cracks due to the impregnation pressure can be prevented.

  Moreover, you may make it have the process of preheating at least 1 said processed body packaged in the said packaging process between the said packaging process and the said impregnation process. In this case, the metal is easily impregnated into the porous sintered body processed by the pre-heat treatment. The preheating temperature is preferably preheated to the same level as the impregnating metal.

  The impregnation step includes a step of accommodating at least one of the workpieces enclosed in the heat retaining member and fixed by the iron fastening means in a die of a press machine; There may be a step of pouring the molten metal into the metal, and a step of pressing down the molten metal with a punch of the press machine to impregnate the molten metal into the workpiece.

  In the impregnation step described above, it is preferable that the pressure at the time of press-fitting with the punch is not more than 5 times the compressive strength of the porous sintered body (including the processed body). Specifically, it is preferable that the pressure at the time of press-fitting by the punch is 1.01 to 202 MPa.

  The manufacturing method further includes a cooling step of cooling the porous sintered body (including a processed body) impregnated with at least the metal, and the cooling step includes adding the metal to the porous sintered body. The heat sink material impregnated with may be cooled in at least a cooling zone to which cooling gas is blown or cooling water is supplied.

  In addition, the said metal can employ | adopt at least 1 sort (s) selected from Cu and Al.

  As described above, according to the heat sink material and the manufacturing method thereof according to the present invention, the adhesion between the porous sintered body made of carbon or graphite and the metal can be improved, and the carbon or graphite and the metal can be improved. It is easy to form a carbide layer at the interface with the heat sink material, and a heat sink material having a thermal conductivity, a thermal expansion coefficient and a strength as a heat sink material can be obtained.

  Embodiments of a heat sink material and a manufacturing method thereof according to the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, the heat sink material 10 according to the present embodiment is configured by impregnating a porous sintered body 12 obtained by firing carbon or graphite into a network to impregnate a metal 14.

  In this case, as carbon or graphite, the thermal conductivity is 100 W / mK or more, preferably 150 W / mK or more (estimated value without pores), more preferably 200 W / mK or more (estimated value without pores). ) Is preferably used.

  In this embodiment, a heat sink material 10 is shown in which Cu (copper) is impregnated into open pores of a porous sintered body 12 made of graphite having a thermal conductivity of 100 W / mK or more. As the metal 14 to be impregnated, Al (aluminum) can be used in addition to Cu (copper).

  In addition, the volume ratio between the porous sintered body 12 and the metal 14 is in a range of 50 vol% to 95 vol% for the porous sintered body 12 and 50 vol% to 5 vol% for the metal 14. As a result, a heat sink material having an average of three orthogonal directions orthogonal or a thermal conductivity of any axial direction of 180 to 220 W / mK or more and a thermal expansion coefficient of 1 ppm / ° C. to 10 ppm / ° C. is obtained. be able to.

  The porosity of the porous sintered body 12 is preferably 5 vol% to 50 vol%. When the porosity is 5 vol% or less, it is impossible to obtain an average of three orthogonal axes or a thermal conductivity of 180 W / mK (room temperature) in any axial direction, and when it exceeds 50 vol%, the porous sintered body 12 It is because the intensity | strength of this falls and a thermal expansion coefficient cannot be suppressed to 15.0 ppm / degrees C or less.

  The average open pore size (pore size) of the porous sintered body 12 is preferably 0.1 to 200 μm. When the pore diameter is less than 0.1 μm, it becomes difficult to impregnate the open pores with the metal 14 and the thermal conductivity is lowered. On the other hand, if the pore diameter exceeds 200 μm, the strength of the porous sintered body 12 decreases, and the thermal expansion coefficient cannot be kept low.

  As a distribution (pore distribution) regarding the average open pores of the porous sintered body 12, it is preferable to distribute 90 vol% or more in 0.5 to 50 μm. When the pores of 0.5 to 50 μm are not distributed by 90 vol% or more, the open pores not impregnated with the metal 14 increase, and the thermal conductivity may be lowered.

  Further, the closed porosity of the heat sink material 10 obtained by impregnating the porous sintered body 12 with the metal 14 is preferably 12 vol% or less. It is because thermal conductivity may fall when it exceeds 5 vol%.

  Note that an automatic porosimeter (trade name “Autopore 9200”) manufactured by Shimadzu Corporation was used to measure the porosity, the pore diameter, and the pore distribution.

  In the heat sink material 10 according to this embodiment, it is preferable to add to the porous sintered body 12 an additive for reducing the closed porosity when the porous sintered body 12 is fired. Examples of the additive include SiC and / or Si. Thereby, closed pores (closed pores) during firing can be reduced, and the impregnation ratio of the metal 14 to the porous sintered body 12 can be improved.

  Further, an element that reacts with the porous sintered body 12 may be added to the porous sintered body 12. Examples of the additive element include one or more selected from Ti, W, Mo, Nb, Cr, Zr, Be, Ta, V, B, and Mn. Thus, when the porous sintered body 12 is fired, a reaction layer (carbide layer) is formed on the surface of the porous sintered body 12 (including the surface of the open pores), and the open pores of the porous sintered body 12 Improves the wettability with the metal 14 impregnated into the metal, makes it possible to impregnate at a low pressure, and to impregnate fine open pores.

  In the present embodiment, an element for improving adhesion at the interface with the porous sintered body 12 is added to the metal 14 impregnated in the porous sintered body 12. In particular, in this embodiment, Fe (iron) is used as an additive element for improving the wettability of the interface. This is because Fe is an element that easily dissolves in the porous sintered body 12 and has an effect of improving adhesion at the interface with the porous sintered body 12 during impregnation. In addition, there is an effect of improving the wettability at the interface with the porous sintered body 12.

  In this case, it is preferable that 0.01 to 4 wt% of Fe is added. When the added amount of Fe exceeds 4 wt%, if the metal 14 to be impregnated is, for example, Cu, a γ phase may be produced during alloying with the Cu, and the hot metal flowability may be reduced. This is because if the metal 14 is, for example, Al, the amount of the θ phase is increased, and there is a possibility that the hot water flow property is similarly lowered.

  Further, it is preferable to add Si to the impregnated metal 14 in order to improve the hot water flowability. That is, there are Sn, P, Si, and Mg as elements that improve the flowability of molten metal (see Patent Document 3), but Si is the only element that is easier to form as carbide than Fe at the interface melted by Fe. Because it became clear.

  In this case, it is preferable that 0.1 to 12 wt% of Si is added. The effect starts to appear when the amount of Si is 0.1% or more. However, if it exceeds 12 wt%, the coefficient of thermal expansion increases, and there is a possibility that 10 ppm / ° C. obtained by networking cannot be satisfied.

  And the following synergistic effects can be acquired by adding Fe and Si to the metal impregnated.

  That is, the addition of Fe improves the adhesion at the interface with the porous sintered body 12, but the solid-liquid coexistence range is narrow even in the range of 0.01 to 4 wt% which is effective as described above. There is a risk of poor flow. As described above, since Si is the only element that improves the hot metal flowability and is easier to form as carbide than Fe at the interface melted by Fe, Si can improve the hot water flowability.

  Accordingly, adhesion by melting at the interface with the porous sintered body 12 is increased by Fe, and carbide is easily formed by Si at the interface. Therefore, the thermal conductivity and thermal expansion coefficient necessary for the heat sink material 10 are obtained. And the heat sink material 10 which has mechanical strength can be obtained.

  The tensile strength of the porous sintered body 12 after impregnated with the metal 14 is preferably 3.5 MPa or more. Tensile strength is affected by adhesion. Even at the same level of impregnation, the difference in adhesion is reflected in the mechanical strength. That is, the higher the adhesion of the metal 14 to the porous sintered body 12, the higher the tensile strength, and the higher the compressive strength proportionally. In this case, if the strength is low, the heat sink material 10 may not be screwed. Therefore, if the tensile strength is 4.5 MPa or more, screw tightening is easy, and if it is 3.5 MPa, handling during soldering and the like becomes easy.

  In addition to the above-described Fe, the metal 14 impregnated in the porous sintered body 12 is one selected from Te, Bi, Pb, Sn, Se, Li, Sb, Tl, Ca, Cd, and Ni. You may make it add the above. In this case, the wettability of the interface between the porous sintered body 12 and the metal 14 is improved, and the metal 14 easily enters the open pores of the porous sintered body 12. In particular, Ni has an effect that graphite is easily dissolved and easily impregnated.

  In addition to Fe described above, at least one selected from Nb, Cr, Zr, Be, Ti, Ta, V, B, and Mn is added to the metal 14 impregnated in the porous sintered body 12. You may do it. As a result, the reactivity between the porous sintered body 12 and the metal 14 is improved, the porous sintered body 12 and the metal 14 are easily in close contact with each other in the open pores, and the generation of closed pores can be suppressed. .

  In addition, the metal 14 impregnated in the porous sintered body 12 improves the hot water flow and reduces residual pores. Therefore, in addition to the above-described Fe and Si, one type selected from Sn, P, and Mg You may make it add the above. As a result, variations in impregnation can be reduced, residual pores can be reduced, and strength can be improved. The same effect can be obtained even if the impregnation pressure is increased. Further, it is preferable to add an element for reducing the melting point to the metal 14. Examples of the additive element include Zn.

  Next, an example of a method for manufacturing the heat sink material 10 according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 2, this manufacturing method includes a firing step S1 for producing a porous sintered body 12 by firing and networking a graphite block (not shown), and the firing step S1. A processing step S2 for processing the porous sintered body 12 to produce one or more blocks, and a block of the porous sintered body 12 is wrapped with a heat insulating member in which a large number of holes are formed, and an iron fastening means The metal 14 is placed in the packaging step S3 which is fixed by the packing process 26 (see FIG. 5), the preheating step S4 for preheating the packaging body 26, and the porous sintered body 12 in the packaging body 26. An impregnation step S5 for impregnating the heat sink material 10 and a cooling step S6 for cooling the heat sink material 10 are provided.

  Since the firing step S1 and the cooling step S6 are described in detail in Patent Document 3 and the like, here, the processing step S2, the packaging step S3, the preheating step S4, and the impregnation step S5 will be described.

  First, one or more blocks (porous sintered bodies) are produced by the processing step S2, but in the subsequent packaging step S3, one block may be packaged or two or more blocks may be packaged. In particular, when two or more blocks are packaged, it is desirable to package them with an object more easily impregnated with metal than the block (porous sintered body 12). In other words, two or more objects can be inserted between the blocks, such as ceramic paper, porous ceramics and honeycombs, so that the pressure during impregnation is close to the hydrostatic pressure. The metal can be impregnated into the block. As a result, poor impregnation (non-impregnation or increased variation in the amount of impregnation) can be eliminated, and the pressure can be made uniform, so that breakage of the block due to the impregnation pressure, generation of cracks, etc. can be prevented. In the following description, a case where two blocks are packaged will be described as an example.

  That is, in the packaging step S3, for example, as shown in FIG. 3, two blocks 20 (first and second blocks 20A and 20B) of the porous sintered body 12 are prepared, and these two blocks 20A and 20B are prepared. Laminate up and down. A mica sheet (first mica sheet 22a), a ceramic sheet (first ceramic sheet 24a), and a second mica sheet 22b are interposed between the first and second blocks 20A and 20B.

  Two mica sheets (third and fourth mica sheets 22c and 22d) are arranged on the upper surface of the first block 20A located above, and two on the lower surface of the second block 20B located below. The mica sheets (fifth and sixth mica sheets 22e and 22f) are arranged.

  Further, as shown in FIG. 4, the entire side surfaces of the first and second blocks 20A and 20B are wound with two mica sheets (seventh and eighth mica sheets 22g and 22h), and the outer periphery thereof. A ceramic sheet (second ceramic sheet 24b) is wound around the sheet. Thereby, one package 26 is completed.

  After that, as shown in FIG. 5, the outer periphery of the package 26 is wound with, for example, a plurality of wires 28, and the first to eighth mica sheets 22a to 22h and the first and second ceramic sheets 24a and 24b are removed. Do not.

  As shown in FIGS. 3 and 4, a large number of holes 30 are formed in the first to eighth mica sheets 22 a to 22 h described above. The hole 30 can be easily formed by punching.

  If only a single package 26 described above is prepared, but a plurality of the packages 26 are prepared in advance, the time required for the subsequent manufacturing process can be reduced.

  The preheating step S4 is performed by putting the package 26 around which the wire 28 is wound into a preheating furnace 32 (see FIG. 6) and heating the package 26. In this heat treatment, one packaging body 26 is accommodated in the preheating furnace 32, and about 60 minutes after the start of heating, for example, a molten metal 64 (a metal impregnated in the porous sintered body 12) to be described later. 14 and melted metal (see FIG. 9), it is desirable to preheat to the same temperature. Specifically, if the molten metal 64 is about 1200 ° C., the preheating temperature of the porous sintered body 12 is desirably 1000 ° C. to 1400 ° C. In addition, although the heating time was about 60 minutes in the above description, it varies depending on the size and number of blocks, and for example, the heating time is 30 to 180 minutes.

  In particular, in the present embodiment, as the preheating furnace 32, the preheating furnace 32 having a volume in which the accommodation space 34 can accommodate the two packaging bodies 26 is used. Therefore, for example, when it is assumed that the heat treatment is completed in 60 minutes, the first package 26 is put in the preheating furnace 32 and heating is started. The first package 26 is taken out when 60 minutes have elapsed from the start of heating and the third package 26 is stored, and 90 minutes have elapsed from the start of heating. At that time, a method of taking out the second package 26 was adopted. Thereby, productivity can be improved.

  Here, one experimental example is shown. This experimental example shows how the temperature of the porous sintered body 12 in the packaging body 26 put into the preheating furnace 32 rises due to the heating of the preheating furnace 32, in particular, the packaging body for the preheating furnace 32 being heated. It was confirmed what effect the temperature rises by taking in and out 26.

  First, in order to measure the temperature of the porous sintered body 12 in the package 26, as shown in FIG. 7, for example, three measurement locations in the second package 26, that is, the first measurement locations. P1 (the center between the first block 20A and the second block 20B), the second measurement point P2 (one place between the first block 20A and the second block 20B) and the third A thermocouple (not shown) was attached to each of the measurement points P3 (center of the lower surface of the second block 20B). In FIG. 7, the first to eighth mica sheets 22 a to 22 h and the first and second ceramic sheets 24 a and 24 b are collectively shown as the heat retaining member 36 in order to simplify the illustration.

  And the change of the temperature of the porous sintered compact 12 until putting the 2nd package 26 in the preheating furnace 32 and taking out from the preheating furnace 32 after 60 minutes passed was plotted. The result is shown in FIG. In FIG. 8, the plot “●” indicates the temperature change at the first measurement point P1, the plot “◯” indicates the temperature change at the second measurement point P2, and the plot “▲” indicates the third measurement. A temperature change at the point P3 is shown.

  The temperature rise of the porous sintered body 12 has stopped when 30 minutes have passed since the second package 26 was inserted. This is because the door of the preheating furnace 32 is opened and the inside of the preheating furnace 32 is opened. This is because the first package 26 is taken out, the third package 26 is accommodated in the preheating furnace 32, and the door is closed again. It took almost 60 seconds to keep the door open. After that, as shown in FIG. 8, the temperature of the porous sintered body 12 has risen to about 1250 ° C. at the lapse of the prescribed 60 minutes, and there is no influence due to opening and closing the door of the preheating furnace 32. is there. That is, it can be seen that if the door opening time is shortened to about 60 seconds, the temperature raising capability by the preheating furnace 32 is not lowered.

  Next, the press machine 40 shown in FIG. 9 was used for the impregnation process S5. The press machine 40 includes a base 42, a mold 44 provided on the base 42, and a punch 48 that moves forward and backward with respect to a space 46 of the mold 44.

  A bottom plate 50 is installed in the space 46 of the mold 44, and a laminated body 56 of a ceramic sheet 52 and a mica sheet 54 is disposed on the bottom plate 50. A laminated body 62 of mica sheets 58 and ceramic sheets 60 is disposed along the inner wall of the mold 44.

  And when performing the impregnation process with respect to the porous sintered compact 12 in the package 26, the package 26 which finished preheating in the space 46 of the metal mold | die 44 is put, and the molten metal 64 of the metal 14 is put on it. After pouring, the laminated body 70 of the ceramic sheet | seat 66 and the mica sheet | seat 68 is covered. Thereafter, the punch 48 is inserted into the space 46 of the mold 44, and the punch 48 is press-fitted into the space 46 of the mold 44 while pushing down the molten metal 64 under the laminated body 70. By the pressing process of the punch 48, the molten metal 64 of the metal 14 is impregnated in the open pores of the porous sintered body 12.

  It is preferable that the pressure at the time of press-fitting with the punch 48 is 5 times or less the compressive strength of the porous sintered body 12, here 1.01-202 MPa. Further, a gas vent hole for venting gas remaining in the porous sintered body 12, a gap portion for venting gas, or the like may be formed at the bottom of the mold 44 or the like. In this case, when the punch 48 is press-fitted, the gas remaining in the porous sintered body 12 passes through the gas vent holes, so that the molten metal 64 is smoothly impregnated into the open pores.

  In this way, by performing the above-described steps, the porous sintered body 12 can be easily impregnated with the metal 14 by graphite, and the porous sintered body 12 is impregnated with the metal 14. The heat sink can improve the rate, has an average of three orthogonal axes, or a thermal conductivity of 180 W / mK or more in any axial direction, and a thermal expansion coefficient of 1 ppm / ° C. to 10 ppm / ° C. The material 10 can be easily obtained.

  Then, when the series of steps leading to the impregnation step S5 is defined as one cycle, the melt 64 of the metal 14 that has not been impregnated in the porous sintered body 12 in the impregnation step S5 in the immediately preceding cycle is added to the current cycle after the second cycle. It is reused as the molten metal 64 of the metal 14 for impregnation in the impregnation step S5 in the cycle. That is, for example, as shown in FIG. 10, the remaining molten metal 64 in the first cycle impregnation step S5 is reused as the molten metal 64 in the second and subsequent impregnation steps S5, and similarly, the second cycle impregnation step S5. The remaining molten metal 64 is reused as the molten metal 64 in the impregnation step S5 of the third cycle. As a result, the material cost can be reduced, which is advantageous in reducing the product cost.

  By the way, in the manufacturing method which concerns on embodiment mentioned above, since the package 26 is tied (fastened) with the wire 28 in packaging process S3, the wire 28 melt | dissolves in the molten metal 64 in the subsequent impregnation process S5. . That is, the molten metal 64 is a metal to which iron (Fe) is added.

  As described above, Fe is an element that is easily dissolved in the porous sintered body 12 and has an effect of improving adhesion at the interface with the porous sintered body 12 during impregnation. However, if the added amount of Fe exceeds 4 wt%, the hot water flowability may be reduced. Therefore, the reuse of the molten metal 64 may be stopped and a new molten metal 64 may be used when the Fe contained in the reused molten metal 64 reaches 4 wt%.

  In the cooling step S6, the heat sink material 10 in which the porous sintered body 12 is impregnated with the metal 14 is transported to a cooling zone (not shown), and is brought into contact with a cooling metal (not shown) installed in the cooling zone. Let The heat sink material 10 is rapidly cooled by the contact with the cooling metal. In this cooling step S6, the heat sink material 10 may be sprayed with a cooling gas, or the cooling metal may be cooled with water.

  Thus, in the manufacturing method of the heat sink material 10 according to the present embodiment, the adhesion between the porous sintered body 12 made of carbon or graphite and the metal 14 can be improved, and the carbon or graphite and The carbide layer can be easily formed at the interface with the metal 14, and the heat sink material 10 having the thermal conductivity, the thermal expansion coefficient, and the strength as the heat sink material 10 can be efficiently produced.

  Here, one experimental example is shown. In this experimental example, for Examples 1 to 8 and Comparative Examples 1 to 10, the state of impregnation of the porous sintered body 12 with the metal 14, the thermal conductivity (plate thickness direction and surface direction) of the heat sink material 10, thermal expansion The rate (200 ° C.) and the compressive strength are observed.

  The composition of the impregnated metal 14 of Examples 1-8 and Comparative Examples 1-10 (main metals and additive elements) and the experimental results are shown in the table of FIG.

  The impregnation situation is greatly affected by the hot water flow. Therefore, the evaluation of the impregnation state was determined by the impregnation rate into the open pores. “◎” indicates an impregnation rate of open pores of 60% or more, “◯” indicates an impregnation rate of open pores of 40% or more, and “×” indicates an impregnation rate of open pores of 40%. Less than.

  When the additive element is only Fe (Examples 1 to 3, Comparative Example 1, Example 7, and Comparative Example 8), the evaluation of the impregnation state is almost “◯”. Since it exceeds 4 wt%, the evaluation is “x”. When the additive element is only Si (Comparative Examples 2 to 7, 9 and 10), as an evaluation of the impregnation state, only Comparative Example 2 is “◯”, and the others are “」 ”. It has become. In addition, when the additive elements are Fe and Si (Examples 4 to 6 and 8), the evaluation of the impregnation state is all “◎”, which is a good result.

  Next, the thermal conductivity is affected by the impregnation condition and the thermal conductivity of the metal 14 to be impregnated. Therefore, when the additive element is only Fe (Examples 1 to 3, Comparative Example 1, Example 7, and Comparative Example 8), the thermal conductivity of the metal 14 decreases as the amount of Fe added increases. The heat conductivity of the heat sink material 10 also tends to decrease. In particular, in Comparative Example 1, measurement was impossible.

  Even when the additive element is only Si (Comparative Examples 2 to 7, 9 and 10) and when the additive element is Fe and Si (Examples 4 to 6 and 8), as the additive amount of Si increases, the metal 14 increases. Since heat conductivity falls, it exists in the tendency for the heat conductivity of the heat sink material 10 to also fall. However, since the impregnation state is good, the decrease in thermal conductivity is small when the addition amount is large.

  Next, the coefficient of thermal expansion tends to be easily affected by the metal 14 as the impregnation condition is better. Therefore, when the impregnation state is “x” and the amount of Fe added is the largest (Comparative Example 1), the amount of the metal 14 impregnated in the porous sintered body 12 is small. Is governed by the coefficient of thermal expansion. In the case where the impregnation state is “◎” (Comparative Examples 3-7, Examples 3-5, Comparative Examples 9, 10, and Example 8), the coefficient of thermal expansion is 5 ppm / ° C. or more, but 10 ppm / ° C. or more. Those (Comparative Examples 7 and 10) are not preferable for obtaining a balance between the thermal expansion coefficient and the thermal conductivity required for an actual electronic component or the like.

  Next, the tensile strength is greatly affected by the adhesion of the metal 14 to the porous sintered body 12. Therefore, even in the same level of impregnation, the difference in adhesion is reflected in the tensile strength. In the evaluation of tensile strength, “◎” indicates 4.5 MPa or more, “◯” indicates 3.5 MPa or more, and “×” indicates less than 3.5 MPa.

  If the tensile strength is less than 3.5 MPa, the heat sink material 10 may not be handled such as soldering or screwed. If the tensile strength is 3.5 MPa or more, handling during soldering becomes easy, and if the tensile strength is 4.5 MPa or more, screwing becomes easy.

  When comprehensive evaluation is made from each evaluation of the impregnation state, thermal conductivity, thermal expansion coefficient, and compressive strength described above, it is “１〜” for Examples 1 to 7, and overall good results are obtained. Recognize.

  It should be noted that the heat sink material and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

It is a perspective view which shows the heat sink material which concerns on this Embodiment. It is process drawing which shows the manufacturing method of the heat sink material which concerns on this Embodiment. It is explanatory drawing (the 1) which shows the process in a packaging process. It is explanatory drawing (the 2) which shows the process in a packaging process. It is a perspective view which shows the state which wound the wire around the package body. It is explanatory drawing which shows a mode that the 1st package, the 2nd package, and the 3rd package are put into a preheating furnace one by one. It is explanatory drawing which shows the position which installed the thermocouple in order to measure the temperature of the porous sintered compact in a package. It is a characteristic view which shows the temperature change of the porous sintered compact in the 2nd package body by the heating of a preheating furnace. It is a block diagram which shows the press used in an impregnation process. It is explanatory drawing which shows reuse of a molten metal. It is a table | surface figure which shows the experimental result by the 1st-8th Example and the 1st-10th comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Heat sink material 12 ... Porous sintered body 14 ... Metal 20, 20A, 20B ... Block 22a-22h ... Mica sheet 24a, 24b ... Ceramic sheet 26 ... Packaging 28 ... Wire 30 ... Hole 32 ... Preheating furnace 40 ... Press Machine 44 ... Mold 48 ... Punch 64 ... Molten metal

Claims (30)

Including carbon or graphite and metal,
The porous sintered body obtained by firing the carbon or graphite to be networked is impregnated with the metal,
The average of the three orthogonal directions or the thermal conductivity of any axial direction is 180 W / mK or more, and
The coefficient of thermal expansion is 1 ppm / ° C. to 10 ppm / ° C.,
A heat sink material, wherein an element for improving adhesion at least at an interface with carbon or graphite is added to the metal. The heat sink material according to claim 1,
The heat sink material, wherein at least the additive element for improving adhesion at the interface is Fe. The heat sink material according to claim 2,
A heat sink material, wherein 0.01 to 4 wt% of Fe is added. The heat sink material according to claim 2 or 3,
A heat sink material, wherein Si is added to the metal in order to improve hot water flow. The heat sink material according to claim 4,
A heat sink material, wherein 0.1 to 12 wt% of Si is added. In the heat sink material according to any one of claims 1 to 5,
The heat sink material, wherein the porous sintered body after impregnated with the metal has a tensile strength of 3.5 MPa or more. In the heat sink material according to any one of claims 1 to 6,
A heat sink material having a closed porosity of 12 vol% or less. In the heat sink material according to any one of claims 1 to 7,
A heat sink material having a thermal conductivity of 100 W / mK or more is used as the carbon or graphite. In the heat sink material according to any one of claims 1 to 8,
A heat sink material, wherein the volume ratio of the carbon or graphite and the metal is in the range of 20 vol% to 95 vol% for the carbon or graphite and 80 vol% to 5 vol% for the metal. In the heat sink material according to any one of claims 1 to 8,
A heat sink material, wherein the volume ratio of the carbon or graphite and the metal is in the range of 50 vol% to 95 vol% for the carbon or graphite and 50 vol% to 5 vol% for the metal. In the heat sink material according to any one of claims 1 to 10,
A heat sink material, wherein a carbide layer is formed on the surface of the carbon or graphite. The heat sink material according to claim 11,
The formation of the carbide layer is based on a reaction between at least the carbon or graphite and an additive element. In the heat sink material according to any one of claims 1 to 12,
The heat sink material, wherein the metal is at least one selected from Cu and Al. In the heat sink material according to any one of claims 1 to 13,
A heat sink material characterized in that the ratio of thermal conductivity is 1: 5 or less in the direction of taking the minimum thermal conductivity and the direction of taking the maximum thermal conductivity. In the heat sink material according to any one of claims 1 to 14,
A heat sink material, wherein the porous sintered body has a porosity of 5 vol% to 50 vol% and an average pore diameter of 0.1 μm to 200 μm. A firing step for producing a porous sintered body by firing and networking carbon or graphite;
A packaging step of wrapping the porous sintered body with a heat retaining member in which a large number of holes are formed, and fixing with a fastening means made of iron,
A method for producing a heat sink material, comprising an impregnation step of impregnating a metal into the porous sintered body. In the manufacturing method of the heat sink material according to claim 16,
The method for manufacturing a heat sink material, wherein the heat retaining member includes a sheet made of mica. The heat sink material manufacturing method according to claim 16 or 17,
The method of manufacturing a heat sink material, wherein the fastening means is a wire. In the manufacturing method of the heat sink material of any one of Claims 16-18,
When the series of steps leading to at least the impregnation step is one cycle, for the second and subsequent cycles, the metal that has not been impregnated in the porous sintered body in the impregnation step in the previous cycle or in the previous cycle is used for impregnation. A method of manufacturing a heat sink material, wherein the heat sink material is reused as a metal. In the manufacturing method of the heat sink material according to claim 19,
A method of manufacturing a heat sink material, wherein the reuse is stopped at a stage where Fe exceeding 4 wt% is contained in the metal reused as the metal for impregnation. In the manufacturing method of the heat sink material of any one of Claims 16-20,
A method for producing a heat sink material, comprising a step of preheating the porous sintered body packaged in the packaging step between the packaging step and the impregnation step. In the manufacturing method of the heat sink material according to any one of claims 16 to 21,
The impregnation step includes
Storing the porous sintered body wrapped in the heat retaining member and fixed by the iron fastening means in a mold of a press machine;
Pouring the molten metal into the mold,
A method of manufacturing a heat sink material, comprising: pressing down the molten metal with a punch of the pressing machine and impregnating the molten metal into the porous sintered body. In the manufacturing method of the heat sink material according to any one of claims 16 to 21,
Between the firing step and the packaging step, it has a processing step of processing the porous sintered body produced in the firing step to produce a processed body,
In the packaging step, at least one of the workpieces is wrapped with a heat retaining member, and fixed with an iron fastening means. In the manufacturing method of the heat sink material according to claim 23,
In the packaging step, when two or more processed bodies are wrapped in a heat retaining member and fixed with an iron fastening means, an object that is more easily impregnated with the metal than the processed bodies is interposed between the processed bodies. A method for producing a heat sink material, characterized by being sandwiched. In the manufacturing method of the heat sink material of Claim 23 or 24,
A method for producing a heat sink material, comprising a step of preheating at least one of the workpieces packaged in the packaging step between the packaging step and the impregnation step. In the manufacturing method of the heat sink material of any one of Claims 23-25,
The impregnation step includes
Storing at least one of the workpieces wrapped in the heat retaining member and fixed by the iron fastening means in a mold of a press;
Pouring the molten metal into the mold,
A method of manufacturing a heat sink material, comprising: pressing down the molten metal with a punch of the pressing machine and impregnating the molten metal into the processed body. In the manufacturing method of the heat sink material of Claim 22 or 26,
A method for producing a heat sink material, wherein a pressure at the time of press-fitting by the punch is 5 times or less of a compressive strength of the porous sintered body. The method of manufacturing a heat sink material according to claim 27,
A method for producing a heat sink material, wherein a pressure during press-fitting by the punch is 1.01 to 202 MPa. In the manufacturing method of the heat sink material according to any one of claims 16 to 28,
Furthermore, it has a cooling step for cooling the porous sintered body impregnated with at least the metal,
The cooling step includes
A method of manufacturing a heat sink material, comprising cooling the heat sink material in which the porous sintered body is impregnated with the metal in at least a cooling zone to which cooling gas is blown or cooling water is supplied. In the manufacturing method of the heat sink material according to any one of claims 16 to 29,
The method of manufacturing a heat sink material, wherein the metal is at least one selected from Cu and Al.

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