Aluminum-copper clad member, method of manufacturing the same, and heat sink

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an aluminum-copper clad member suitably used as, for example, a heat exchanger, a radiator, a heat pipe and a heat sink, and also relates to a manufacturing method thereof. Furthermore, the present invention relates to a heat sink, and more specifically to, a heat sink suitably used for cooling exothermic devices installed in various electric apparatuses.

[0003] 2. Description of Related Art

[0004] Heat exchangers, radiators, heat pipes and heat sinks are widely used in the industrial fields of electric devices, communication apparatuses and transport apparatuses such as automobiles and airplanes. They are required to be not only excellent in heat transfer performance but also light in weight and small in size. Thus, various improvements have been made from the view points of materials and configurations.

[0005] As for the view point of materials, in place of copper-base material which is excellent in heat transfer performance and thermal diffusion performance but defective in weight, aluminum-base material, which is light in weight and excellent in heat transfer performance ranked next to copper, is widely used.

[0006] In an aluminum heat exchanger used in the field of electric device industries, various improvements including an increasing of the cooling area and the thickness of components are made in order to improve heat transfer performance thereof. However, since such an aluminum heat exchanger has been remarkably improved in size, weight and performance, it becomes difficult to further improve the heat transfer performance by increasing the cooling area and the thickness of components. Furthermore, in cases where water is used as operation fluid for heat pipes, there are such drawbacks that the heat pipe performance of aluminum heat exchanger deteriorates due to non-condensing gases generated therein.

[0007] From the view point of configuration, in a heat sink, for example, a number of thin-plate like fins are integrally formed on a heat radiation board to increase the heat radiation area. Such a heat sink, which is usually an aluminum extruded article, is advantageous to an electric device, such as a computer having a number of exothermic devices, for quickly discharging heat generated by the exothermic devices. In the heat sink of the aforementioned shape, in order to improve the heat radiation performance, it is important to increase the heat radiation area. In order to increase the heat radiation area, it is necessary to increase the number of fins, decrease the fin thickness, narrow the fin intervals and increase the fin height. It is, however, difficult to manufacture the heat sink of such a fin shape due to restrictions of extrusion technology.

[0008] Moreover, since improving the fin functions is not sufficient to enhance the heat radiation performance of the heat sink, it is necessary to improve the thermal diffusion function of the heat sink substrate to be attached to an exothermic device. The thermal diffusion function can be improved by increasing the thickness of the substrate. However, since the installation space of a heat sink is limited due to the miniaturization of the whole apparatus in which the heat sink is installed, an increased thickness of the substrate results in a decreased fin height, which in turn decreases the heat radiation area. Moreover, increasing the thickness of the substrate contradicts decreasing the weight of the apparatus.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide an aluminum-copper clad member which is excellent in heat radiation performance and suitably used for a heat sink or the like.

[0010] It is another object of the present invention to provide a method of manufacturing the aluminum-copper clad member.

[0011] It is still another object of the present invention to provide a heat sink which is capable of improving the heat radiation performance without increasing the size and/or weight.

[0012] According to one aspect of the present invention, an aluminum-copper clad member comprises an aluminum-base member, a copper-base member and an insertion member made of pure aluminum or Japanese Industrial Standard (hereinafter referred to as “JIS”) JIS A1xxx series aluminum alloy, wherein the aluminum-base member and the copper-base member are clad via the insertion member. According to the aluminum-copper clad member, since the aluminum-base member and the copper-base member are clad via the insertion member made of pure aluminum or JIS A1xxx series aluminum alloy which is easily clad to the copper-base member even in a cold rolling, oxidization of the copper-base member and generation of compounds between different materials can be decreased, resulting in high joining strength.

[0013] It is preferable that the copper-base member is made of oxygen free copper or phosphorus processed deoxidized copper. In this case, the generation of oxides is effectively restrained, resulting in excellent joining strength of the clad member.

[0014] In the aforementioned aluminum-copper clad member, since the clad member has lightness of aluminum and heat transfer performance, thermal diffusion performance and corrosion resistance of copper, when used as heat exchanger material, it is possible to realize a heat transfer performance exceeding that of aluminum while restraining the weight increase as compared to a copper heat sink. Moreover, corrosion resistance equivalent to copper can be obtained by applying the aforementioned clad member such that the copper-base member constitutes an easy-to-corrode portion.

[0015] According to another aspect of the present invention, a method of manufacturing an aluminum-copper clad member includes the steps of: joining an insertion member made of pure aluminum or JIS A1xxx series aluminum alloy to a copper-base member by a cold rolling to obtain a joined two members; joining an aluminum-base member to the insertion member by a cold rolling or a hot rolling to obtain a joined three members; and heat treating the joined two members before joining the aluminum-base member to the insertion member by a cold rolling or a hot rolling, or heat treating the joined three members after joining the aluminum-base member to the insertion member by a cold rolling or a hot rolling.

[0016] According to this method, even if the joining of the copper-base member and the insertion member to be directly connected thereto is performed by a cold rolling, high joining strength therebetween can be obtained, resulting in excellent joining of the copper-base member and the aluminum-base member. Moreover, since the aforementioned clad member is obtained through rolling steps, it is possible to manufacture the aluminum-copper clad member having a wide width and a long length. Therefore, a heat exchanger member, which requires lightness, good heat transfer performance, good corrosion resistance and large surface area, can be manufactured.

[0017] In the aforementioned method, it is preferable that a roll-working rate of the insertion member is set to 30% or more. Furthermore, it is preferable that a roll-working rate of the aluminum-base member is set to 40% or more. In cases where the roll-working rate of the insertion member is set to 30% or more, and/or the roll-working rate of the aluminum-base member is set to 40% or more, excellent joining strength can be obtained.

[0018] Furthermore, it is preferable that the heat treating is performed at from 200° C. to 400° C. This also enhances the joining strength.

[0019] According to still another aspect of the present invention, a heat sink includes a heat radiation portion made of aluminum-base material and provided with a plurality of tongue-like fins formed by skiving a surface layer of one side of the heat radiation portion; and a thermal diffusion portion made of copper-base material and joined to the other side of the heat radiation portion in a closely fitted manner.

[0020] In the aforementioned heat sink, since it includes a heat radiation portion made of aluminum-base material and provided with a plurality of tongue-like fins formed by skiving a surface layer of one side of the heat radiation portion and a thermal diffusion portion made of copper-base material and joined to the other side of the heat radiation portion in a closely fitted manner, when used as heat exchanger material, it is possible to realize a heat transfer performance exceeding that of aluminum while restraining the weight increase as compared to a copper heat sink. Especially, since the thermal diffusion portion in contact with the heat radiation portion is made of a copper-base member, an excellent cooling effect can be obtained without increasing the volume of the heat sink while maintaining the conventional fin height. Therefore, the heat sink is suitably used as a heat sink in the electric device having a limited installation space.

[0021] In the aforementioned heat sink, it is preferable that the thermal diffusion portion is a flat plate. In this case, the heat sink can be manufactured easily.

[0022] Furthermore, it is preferable that the thermal diffusion portion includes a heat exchanging medium chamber inside thereof and that the heat exchanging medium chamber is provided with wicks formed on an inner wall thereof. In cases where the thermal diffusion portion includes the heat exchanging medium chamber inside thereof, the heat sink can be used as a heat pipe and the thermal diffusion performance and heat radiation performance can be further improved.

[0023] Furthermore, since the thermal diffusion portion is formed by corrosion resistant copper-base material, it is possible to use water as heat exchange medium.

[0024] In cases where the heat exchanging medium chamber is provided with wicks formed on an inner wall thereof, since the circulation of heat exchange medium is enhanced within the chamber due to the capillary phenomenon, the thermal diffusion performance and the heat radiation performance can be further improved.

[0025] According to still yet another aspect of the present invention, a heat sink includes a heat radiation portion made of aluminum-base material and provided with a plurality of tongue-like fins formed by skiving a surface layer of one side of the heat radiation portion; and a thermal diffusion portion made of copper-base material and joined to the other side of the heat radiation portion via an insertion member made of pure aluminum or JIS A1xxx series aluminum alloy. In this heat sink, oxidization of the copper-base member and generation of the compounds between the different materials are restrained at the time of junction, resulting in high joining strength. Moreover, this heat sink also has outstanding lightness, heat transfer performance, thermal diffusion performance and corrosion resistance.

[0026] In the aforementioned heat sink, it is preferable that the thermal diffusion portion is a flat plate. In this case, the heat sink can be manufactured easily. Furthermore, it is preferable that the thermal diffusion portion includes a heat exchanging medium chamber inside thereof and that the heat exchanging medium chamber is provided with wicks formed on an inner wall thereof. In cases where the thermal diffusion portion includes the heat exchanging medium chamber inside thereof, the heat sink can be used as a heat pipe and the thermal diffusion performance and heat radiation performance can be further improved.

[0027] Furthermore, since the thermal diffusion portion is formed by corrosion-resistant copper-base material, it is possible to use water as heat exchange medium.

[0028] In cases where the heat exchanging medium chamber is provided with wicks formed on an inner wall thereof, since the circulation of heat exchange medium is enhanced within the chamber due to the capillary phenomenon, the thermal diffusion performance and the heat radiation performance can be further improved.

[0029] Other objects and the features of the present invention will be apparent from the following detailed description of the invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be more fully described and better understood from the following description, taken with the appended drawings, in which:

[0031]
FIG. 1 is a cross sectional view of an aluminum-copper clad member according to the present invention;

[0032]
FIG. 2 is a cross sectional view of a cooling tube made of the aluminum-copper clad member shown in FIG. 1;

[0033]
FIG. 3 is a perspective view showing a test heat sink;

[0034]
FIG. 4 is a cross sectional view showing an example A of a heat sink according to the present invention;

[0035]
FIG. 5 is an explanatory view showing the manufacturing process of the heat sink of the example A;

[0036]
FIG. 6 is an explanatory view showing another manufacturing processes of the heat sink of the example A;

[0037]
FIG. 7 is a perspective view showing an example B of a heat sink according to the present invention;

[0038]
FIG. 8 is an explanatory view showing the manufacturing process of the heat sink of the example B;

[0039]
FIG. 9 is an explanatory view showing another manufacturing processes of the heat sink of the example B;

[0040]
FIG. 10 is a cross sectional view showing an example C of a heat sink according to the present invention;

[0041]
FIG. 11 is a cross sectional view showing an elevation view and manufacturing process of an example D of a heat sink according to the present invention;

[0042]
FIG. 12 is a cross sectional view showing an example E of a heat sink according to the present invention; and

[0043]
FIG. 13 is a cross sectional view showing an example F of a heat sink according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Aluminum—Copper Clad Member

[0045] As shown in FIG. 1, the aluminum—copper clad member 1 according to the present invention includes an aluminum-base member 11, a copper-base member 13 and an insertion member 12. The insertion member 12 is made of pure aluminum or JIS A1xxx series aluminum alloy and interposed between the copper-base member 13 and the aluminum-base member 11.

[0046] The composition of the aforementioned aluminum-base member 11 is not specifically limited. As the aluminum-base member 11, for example, high-grade pure aluminum, aluminum or its aluminum alloy of JIS A1xxx series, Al—Cu series alloy of JIS A2xxx series, Al—Mn series alloy of JIS A3xxx series, Al—Si series alloy of JIS A4xxx series, Al—Mg series alloy of JIS A5xxx series, Al—Si—Mg series alloy of JIS A6xxx series, Al—Zn—Mg—Cu series alloy and Al—Zn—Mg series alloy of JIS A7xxx series, etc., can be used widely.

[0047] The composition of the aforementioned copper-base member 13 is not specifically limited. It is recommended to use oxygen free copper or phosphorus processed deoxidized copper as the copper-base member because they can restrain generation of oxides or compounds with aluminum.

[0048] As for the insertion member 12, it is necessary to use pure aluminum which is easily joined by a cold rolling to the copper-base member 13 as different metal material, or JIS A1xxx series aluminum alloy with few added elements. It is specifically recommended that the insertion member 12 is made of a high-grade pure aluminum of 99.90% purity, or an aluminum alloy of purity more than that of JIS A1050 alloy among JIS A1xxx series aluminum alloys.

[0049] By using the aforementioned insertion member 12, the insertion member can be joined by a cold rolling with high joining strength. Generally, between the aluminum-base member 11 and the copper-base member 13, thermal resistance arises due to the difference in thermal conductivity. However, the thermal resistance can be reduced by interposing pure aluminum or JIS A1xxx series aluminum alloy having higher thermal conductivity among aluminum-base materials as the aforementioned insertion member 12.

[0050] Method of Manufacturing the Aluminum—Copper Clad Member

[0051] The aforementioned aluminum—copper clad member 1 is manufactured by, for example, the following method.

[0052] First, the insertion member 12 is joined to the copper-base member 13 by a cold rolling. Since the insertion member 12 is made of pure aluminum or JIS A1xxx series aluminum alloy, it is small in modification resistance and excellent in joining performance to the copper-base member 13 by a cold rolling. Moreover, since the insertion member 12 is joined to the copper-base member 13 by a cold rolling, oxidization of the copper-base member 13 and the generation of compounds with the ingredients of the insertion member 12 are restrained. Thus, the causes for deteriorating the joining strength can be eliminated. Although the cold roll-working rate is desirable to be 30% or more in order to obtain sufficient joining strength, when it exceeds 70%, there is a possibility that the materials may break due to the work hardening. More preferably, the roll-working rate is from 40% to 70%.

[0053] Next, the aluminum-base member 11 is joined to the insertion member 12 by a cold rolling or a hot rolling. In this rolling, since the surface of the copper-base member 13 is already covered with the insertion member 12 to be intercepted from atmosphere, a hot rolling or a cold rolling may be performed. In order to securely adhere the aluminum-base member 11 to the insertion member 12, the roll-working rate is preferably set to 40% or more depending on the required final thickness. In cases of performing a hot rolling, it is preferable that the rolling temperature is set to from 100 to 350° C. and that the hot rolling is performed immediately after reaching the target temperature so as not to grow compound phase at the interface between the copper-base member 13 and the insertion member 12. In this rolling, since both the insertion member 12 and the aluminum-base member 11 are aluminum, they are firmly joined each other, which results in a secure joining of the aluminum-base member 11 and the copper-base member 13 via the insertion member 12.

[0054] In the aforementioned series of joining steps, the joined two members are heat treated before joining the aluminum-base member 11 to the insertion member 12 to securely join the copper-base member 13 and the insertion member 12. Alternatively, after joining the aluminum-base member 11 on the insertion member 12, the joined three members are heat treated to securely joining the aluminum-base member 11, the insertion member 12 and the copper-base member 13. In order to suppress the growth of compounds at the interface between the copper-base member 13 and the insertion member 12 and to obtain high joining strength therebetween, it is preferable to perform the aforementioned heat treatment within the temperature range of from 200 to 400° C. It is preferable to perform the aforementioned heat treatment at the temperature of from 220 to 300° C. Moreover, it is preferable to perform the heat treatment within one hour so as not to grow compounds. When the thickness of the compounds layer is controlled to 10 μm or less by adjusting the heat treatment conditions, a further improved joining condition can be obtained.

[0055] It is possible to manufacture a securely joined aluminum—copper clad member by heat treating the joined two members before joining the aluminum-base member 11 to the insertion member 12, or the joined three members after joining the aluminum-base member 11 to the insertion member 12. However, in cases where the aluminum-base member 11 is joined on the insertion member 12 by a cold rolling, the heat treatment is preferably subjected to the joined three members after joining the aluminum-base member 11 to the insertion member 12.

[0056] Since the aforementioned aluminum—copper clad member 1 according to the present invention has lightness of aluminum and heat transfer performance, thermal diffusion performance and corrosion resistance of copper, the clad member can be suitably used as heat exchanger materials.

[0057] For example, the aluminum—copper clad member 1 can be manufactured into a heat exchanging tube 2 as shown in FIG. 2. In this heat exchanging tube 2, when the copper-base member 13 is located inside the tube, refrigerant contacts the copper-base member 13 which is excellent in corrosion resistant. This enhances not only the heat transfer performance but also the corrosion resistance. Moreover, the aluminum—copper clad member 1 can also be manufactured into a heat sink with a plurality of tongue-like fins which will be detailed.

EXAMPLE

[0058] The aluminum—copper clad member and the method of manufacturing the clad member according to the present invention will be detailed below.

[0059] As the aforementioned copper-base member 13, an oxygen free copper board and a phosphorus processed deoxidized copper board, each of which is 8 mm in thickness, 100 mm in width and 150 mm in length, were prepared.

[0060] As the aforementioned insertion member 12, three kinds of 99.999% purity aluminum plates 94 mm width and 150 mm length with different thickness, i.e., 0.1 mm thickness, 0.5 mm thickness and 1.0 mm thickness, were prepared.

[0061] As the aforementioned aluminum-base member 11, JIS A1100 or JIS A6063 aluminum plate 100 mm width and 200 mm length with different thickness, i.e., 2.0 mm thickness, 5.0 mm thickness, 10.0 mm thickness and 15.0 mm thickness, were prepared.

[0062] The combination of the aforementioned members are shown in Table 1.

[0063] In manufacturing the clad member, the insertion member 12 was placed on the copper-base member 13, and then they are subjected to a cold rolling at the roll-working rate shown in Table 1 to join them.

[0064] Subsequently, the joined members 12 and 13 according to the example Nos. 1-13 were held for 1 hour at the temperature shown in Table 1 to perform a middle heat treatment. On the other hand, the joined members according to the examples of the inventive example Nos. 14-17 were proceeded to the following process without being subjected to the middle heat treatment.

[0065] Next, the aluminum-base member 11 shown in Table 1 was put on the insertion member 12 of the aforementioned joined member and subjected to a cold rolling or a hot rolling at 500° C. at the roll-working rate shown in Table 1 to join them.

[0066] Furthermore, as for the example Nos. 14-17 to which the middle heat treatment was not executed, they were held at the temperature shown in Table 1 for 1 hour to perform a final heat treatment.

[0067] The examples Nos. 1-13 to which the middle heat treatment was executed, were not subjected to the final heat treatment.

[0068] On the other hand, as for the clad member according to the comparative example Nos. 1-4 with no insertion member, the clad members were manufactured by performing a hot rolling an aluminum-base member and a copper-base member at the temperature and the roll-working rate shown in Table 1.

[0069] The joining rate and the joining strength of these clad members were evaluated. The joining rate was evaluated by an ultrasonic inspection. The joining rate (%) was calculated as follows: the joining rate (%)=(non-joined area/measured area)×100. The joining strength was evaluated by falling the test piece onto an iron floor 20 times from the height of 1.5 m, and cracks or destructions of the test piece was examined. These evaluation results are shown in Table 1.

1TABLE 1(Manufacturing conditions and Evaluation)InsertionMiddleAluminum-baseHot/ColdmemberCold roll-heatmemberroll-Final heatJoiningClad member(Pure Al)workingtreatmentMaterial/ThicknessworkingtreatmentrateJoiningNo.Cupper-base memberThickness(mm)rate(%)(° C.)(mm)rate (%)(° C.)(%)strengthExample1Oxygen free copper0.142250A1100/2.0Heat/58—100No crack2Oxygen free copper0.545300A1100/5.0Heat/58—100No crack3Phosphorus processed0.555350A6063/10.0Cold/50—100No crackdeoxidized copper4Oxygen free copper0.559400A1100/10.0Heat/45—100No crack5Phosphorus processed1.065300A6063/10.0Cold/58—100No crackdeoxidized copper6Oxygen free copper1.068350A1100/2.0Cold/58—100No crack7Phosphorus processed1.068400A6063/10.0Heat/55—100No crackdeoxidized copper8Phosphorus processed1.068200A6063/10.0Heat/53—100No crackdeoxidized copper9Oxygen free copper0.565250A6063/15.0Cold/50—100No crack10Phosphorus processed0.565350A6063/150Cold/50—100No crackdeoxidized copper11Oxygen free copper0.565350A6063/15.0Heat/58—100No crack12Phosphorus processed0.565400A1100/5.0Heat/58—100No crackdeoxidized copper13Oxygen free copper1060350A6063/10.0Heat/50—100No crack14Oxygen free copper1.068—A1100/2.0Cold/58350100No crack15Phosphorus processed1.065—A6063/100Cold/58300100No crackdeoxidized copper16Oxygen free copper0.565—A6063/15.0Cold/50350100No crack17Phosphorus processed0.555—A6063/10.0Cold/50300100No crackdeoxidized copperComparative1Oxygen free copperNo insertion memberA1100/10.0Heat/4950Destroyedexample2Oxygen free copperA6063/100Heat/5860Cracks3Phosphorus processedA6063/10.0Heat/5970Destroyeddeoxidized copper4Phosphorus processedA1100/10.0Heat/5895Cracksdeoxidized copper

[0070] Furthermore, the heat transfer performance of the test heat sink 20 shown in FIG. 3 manufactured by the aluminum—copper clad members according to the example Nos. 2, 8 and 16 and the non-clad aluminum alloy member having the same thickness as the aforementioned clad members, were compared and evaluated.

[0071] The aforementioned test heat sink 20 was prepared by cutting out the aforementioned clad member into a plate of 80 mm width (W) and 60 mm depth (D) and forming three rows of tongue-like fins 22 of 30 mm height (FH) at the fin pitch (FP) of 2 mm. The copper-base member side constitutes a plate-like base portion 21. As for the test heat sink 20 made of the non-clad aluminum alloy member, the test heat sink 20 was prepared by cutting out the aforementioned non-clad aluminum alloy member into the same size as the aforementioned clad member and forming the same tongue-like fins 22 as in the aforementioned clad member on one surface. The other side constitutes a plate-like base portion 21.

[0072] As shown in FIG. 3, a heat source 23 was attached to the rear central portion of the base portion 21 of each test heat sink 20 in a close-fitted manner. Then, the test heat sink 20 was heated by the heat source 23 and, at the same time, cooled by blowing air of 2 m/sec wind velocity onto the test heat sink from the upper side of the fins. In this state, the temperature of the right above portion 24 of the heat source 23, the temperature of the cooling air, and the input heat quantity (w) of the heat source 23 were measured respectively, and the thermal resistance (R) of each test heat sink was calculated by the following formula (f1) for evaluating the heat transfer performance

R=
(Te−Tair)/Q (f1)

[0073] wherein R is a thermal resistance (° C./w) of the heat sink, Te is a temperature (° C.) at the right above portion 24 of the heat source 23, Tair is a temperature (° C.) of the cooling air, Q is an input heat quantity(w) of the heat source 23.

[0074] The evaluated results are shown in Table 2.

2TABLE 2Thermal transfer performance of Al-Cu clad member and non-cladmemberThermal resistanceTest No.Test pieceR(° C./W)IClad member (Example No. 2)0.510Oxygen free copper-A1100Middle heat treatmentA1100 member (non-clad)0.667IIclad member (Example No. 8)0.534phosphorus processeddeoxidized copper-A6063Middle heat treatmentA6063 (non-clad)0.682IIIclad member (Example No. 16)0.528Oxygen free copper-A6063Final heat treatmentA6063 member (non-clad)0.682

[0075] From the results shown in Table 1, as for the aluminum—copper clad member in which the insertion member was interposed, it is confirmed that different metal members are firmly joined at the whole surface thereof to have high joining strength. Moreover, from the results shown in Table 2, it is also confirmed that each aluminum—copper clad member is excellent in heat transfer performance exceeding the heat transfer performance of aluminum without causing deterioration of heat transfer performance due to the joined portions.

[0076] Heat Sink

[0077] FIGS. 4-11 show the examples A-D of heat sinks according to the present invention, each of which consists of a thermal-diffusion portion of aluminum-base material and a heat radiation portion of copper-base material.

[0078] Moreover, FIGS. 12-13 show examples E-F of heat sinks according to the present invention, each of which is made of the aforementioned aluminum—copper clad member 1. Each of these heat sinks consists of a heat-radiation portion of aluminum-base material and a thermal diffusion portion of copper-base material joined to the heat-radiation portion via an insertion member. The shape and the manufacturing method of each heat sink will be explained as follows.

[0079] Embodiment A

[0080] The heat sink 31 shown in FIG. 4 consists of a heat radiation portion 41 having a number of tongue-like fins 42 on one surface side thereof and a plate shaped thermal diffusion portion 51 joined to the other side of the heat radiation portion 41.

[0081] As shown in FIG. 5, the heat sink 31 is manufactured by joining a plate-shaped aluminum-base member 43 and a plate-shaped copper-base member 51 and then forming tongue-like fins 42 on the aluminum plate 43.

[0082] In the aforementioned manufacturing process, since both the members are flat plates, the joining method may be any one of well-known methods including a rolling method, a friction joining method, an ultrasonic joining method and a brazing method. Moreover, the tongue-like fins 42 may be formed by a well known method.

[0083] As shown in FIG. 6, the heat sink 31 can also be manufactured by forming tongue-like fins 42 on the aluminum plate to obtain a heat radiation portion 41, and then joining the heat radiation portion 41 onto a copper-base plate 51. In this case, the joining of the heat radiation portion 41 and the thermal diffusion portion 51 must be performed by a method other than a rolling method.

[0084] It is preferable that the thickness of the aluminum plate 43 before forming the tongue-like fins 42 is from 1 mm to 10 mm. If the fin height is less than 1 mm, the fin height becomes lower, resulting in decreased heat radiation performance. On the other hand, even if the fin height exceeds 10 mm, it does not contribute to form thinner and higher tongue-like fins 42.

[0085] Moreover, it is preferable that the thickness of the plate-shaped copper-base member constituting a thermal diffusion portion 51 is from 1.5 mm to 8 mm so as to secure the excellent thermal diffusion performance as a plate-shaped thermal diffusion portion and to avoid excessive weight.

[0086] Embodiment B

[0087] The heat sink 32 shown in FIG. 7 consists of a heat radiation portion 41 having a number of tongue-shaped fins 42 formed on one surface thereof and a thermal diffusion portion 61 joined to the other side of the heat radiation portion 41. The thermal diffusion portion 61 has a hollow chamber 62 for heat exchanging medium. This heat sink 32 can be served as a heat pipe by vacuuming the chamber 62 and filling the vacuumed chamber with heat exchange medium such as water.

[0088] The heat sink 32 can be manufactured by joining the heat radiation portion 41 manufactured by forming the tongue-shaped fins 42 on the aluminum plate and the thermal diffusion portion 61 having a hollow portion, as shown in FIG. 8. Alternatively, the tongue-shaped fins 42 may be formed after joining the two members as shown in FIG. 5. Alternatively, as shown in FIG. 9, the similar heat exchanging chamber 32′ can be manufactured by joining a copper-base member 65 having a U-shaped cross-section to the heat sink 31 obtained by joining the plate-shaped thermal diffusion portion 51 and the heat radiation portion 41 as shown in FIG. 4. In this case, the plate-shaped thermal diffusion portion 51 and the copper-base member 65 of a U-shaped cross-section constitute the thermal diffusion portion 64.

[0089] In this embodiment, the joining method of the heat radiation portion 41 and the thermal diffusion portion 61, the joining method of the heat radiation portion 41 and the U-shaped member 65, the forming method of the tongue-shaped fins 42, and the size of the heat radiation portion 41 are the same as in the example A. Since the thermal diffusion portion 61 and 64 of the heat sink 32 and 32′ functions as a heat pipe, the thermal diffusion performance and the heat radiation performance of the thermal diffusion portion 61 and 64 will be increased. Therefore, the thickness of the thermal diffusion portion 61 and 64 may be thinner than that of the plate-shaped thermal diffusion portion 51. The thickness is preferably from 1.2 mm to 5 mm. Since the thermal diffusion portion 61 is made of copper-base material, it is excellent in corrosion resistance, and water can be used as heat exchanging medium.

[0090] Embodiment C

[0091]
FIG. 10 shows a heat sink according to an embodiment C. This heat sink 33 has a thermal diffusion portion 66 which functions as a heat pipe like the heat sink 32 according to the embodiment B. However, this heat sink 33 is different from the aforementioned heat sink 32 in that wicks are formed in the inner wall of the heat exchanging medium chamber 63. Thus, forming wicks by attaching a wire net or sintering copper powder to the inner wall of the heat exchanging medium chamber 63 enhances the circulation of the heat exchange medium within the chamber, resulting in improved performance of the heat pipe due to the capillary phenomenon, which improves the thermal diffusion performance and the heat radiation performance of the heat sink.

[0092] Embodiment D

[0093]
FIG. 11 shows a heat sink 34 having a heat pipe 73 embedded in the thermal diffusion portion 71. In the heat pipe 73, heat exchange medium 72 is enclosed.

[0094] In the heat sink 32 and 33 of the aforementioned embodiments B and C, the thermal diffusion portion 61 and 66 itself constitutes a heat pipe. The heat pipe is formed by vacuuming air and introducing heat exchanging medium after the assembly of each members. Thus, the opening for vacuuming air or introducing heat exchanging medium is exposed to the outer surface of the heat sink.

[0095] On the other hand, in the heat sink 34 of this embodiment, after introducing heat exchange medium through an opening and closing the opening to complete a heat pipe 73, the heat pipe 73 is assembled in the state that this heat pipe 73 is embedded in the thermal diffusion portion 71, and then the tongue-shaped fins 42 are formed. Therefore, the heat pipe 73 is surrounded by the thermal diffusion portion 71 and cannot be seen from the outside.

[0096] The heat sink 34 can be manufactured by, for example, the process shown in FIG. 11.

[0097] That is, the completed heat pipe 73 is loaded into the dented portion 75 of the outer shell member 74. The dented portion 75 has an inner shape corresponding to the outside shape of the heat pipe 73. Therefore, the heat pipe 73 is closely fitted in the dented portion 75. Thereafter, the outer shell member 74 in which the heat pipe 73 is loaded is joined, for example, to the heat sink 31 in which the plate-shaped thermal diffusion portion 51 and the heat radiation portion 41 as shown in FIG. 6 are joined. This heat-pipe-embedded-type heat sink 34 has high reliability since the previous prepared reliable heat pipe is used.

[0098] Embodiment E

[0099]
FIG. 12 shows a heat sink including a heat radiation portion 81 on which tongue-shaped fins 42 are formed, a thermal diffusion portion 82 to be attached to a heating element and an insertion member 12 interposed between the heat radiation portion 81 and the thermal diffusion portion 82 to join them. This heat sink 35 is manufactured by forming tongue-shaped fins 42 on the surface of the aluminum-base member 11 of the previously manufactured aluminum—copper clad member 1. The copper-base member 13 constitutes a plate-shaped thermal diffusion portion 82 as it is. The preferable thickness of each part before machining is the same as the embodiment A.

[0100] The heat sink 35 is excellent in thermal diffusion performance and light in weight like the embodiment A. Moreover, since the heat radiation portion 81 and the thermal diffusion portion 82, which are different metal materials, are joined via the insertion member 12, the joining strength is excellent.

[0101] Embodiment F

[0102]
FIG. 13 shows a heat sink 36 with a heat exchanging medium chamber 84 formed in the thermal diffusion portion 83. In this heat sink 36, the heat exchanging medium chamber 84 is formed by joining a copper-base member 65 of a U-shaped cross-section to the heat sink 35 of the embodiment E. The copper-base member 13 and the U-shaped member 65 in this clad member 1 constitutes a thermal diffusion portion 83. The preferable thickness of each part before machining is the same as the embodiment B.

[0103] The heat sink 36 is excellent in thermal diffusion performance and light in weight like the embodiment B. Moreover, since the heat radiation portion 81 and the thermal diffusion portion 83, which are different metal materials, are joined via the insertion member 12, the joining strength is excellent.

[0104] Furthermore, in the heat sink 36, wicks may be provided to the inner wall of the heat exchanging medium chamber 84 like the heat sink 33 shown in FIG. 10.

[0105] In the aforementioned heat sinks 31, 32, 32′, 33, 34, 35 and 36, the composition of the aluminum-base member constituting the heat radiation portion 41 and 81 is not specifically limited. For example, high-grade pure aluminum, aluminum or its aluminum alloy of JIS A1xxx series, Al—Cu series alloy of JIS A2xxx series, Al—Mn series alloy of JIS A3xxx series, Al—Si series alloy of JIS A4xxx series, Al—Mg series alloy of JIS A5xxx series, Al—Si—Mg series alloy of JIS A6xxx series, Al—Zn—Mg—Cu series alloy and Al—Zn—Mg series alloy of JIS A7xxx series, etc., can be used. Among the aforementioned materials, JIS A6xxx series alloy can be recommended in consideration of forming the tongue-shaped fins.

[0106] Moreover, the composition of the copper-base member constituting the thermal-diffusion portion 51, 61, 62, 65, 66, 71, 82 and 83 is not specifically limited. For example, tough pitch copper, oxygen-free copper or phosphorus processed deoxidized copper can be used. Among the aforementioned materials, oxygen free copper or phosphorus processed deoxidized copper can be recommended in consideration of controlling the generation of oxides or aluminum compounds when joining to the heat radiation portion 41 which is different in metal material.

[0107] Moreover, in the embodiments E-F, as the aforementioned insertion member 12, it is recommended to use high-grade pure aluminum of 99.90% purity or more, and JIS A1050 alloy among JIS A1xxx series aluminum as in the insertion member in an aforementioned aluminum—copper clad member.

[0108] The present invention claims priorities based on Japanese Patent Applications Nos. 2000-66807 filed on Mar. 10, 2000 and 2000-66942 filed on Mar. 10, 2000, the content of which is incorporated hereinto by reference in its entirety.

[0109] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intent, in the use of such terms and expressions, of excluding any of the equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

Number	Date	Country	Kind
2000-66807	Mar 2000	JP
2000-66942	Mar 2000	JP

Aluminum-copper clad member, method of manufacturing the same, and heat sink

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