TWI538992B - Porous thermal conductive substrate and its making method - Google Patents

Description

Porous heat conductive substrate and manufacturing method thereof

The present invention relates to a method for producing a thermally conductive substrate, and more particularly to a porous thermally conductive substrate having porosity and a method for producing the same.

As the semiconductor process technology develops more and more mature, the integration of semiconductor components is becoming higher and higher. Therefore, "heat dissipation" has become one of the important technologies of semiconductor components. Especially for high-power components, the temperature of the electronic product rises rapidly due to the large increase in thermal energy generated when the components are activated. For every 10 °C increase in the average operating temperature of electronic components, component life is reduced by 50%. Therefore, how to develop a heat dissipation method that is more suitable for the demand of high-power components is a difficult problem to be overcome by related manufacturers.

Generally, the heat dissipation of the components is generally provided with a heat dissipation structure (for example, heat dissipation fins and heat sinks) on the components, and the heat dissipation structure is used to derive the waste heat generated by the power components. The constituent material of the heat dissipating structure is generally a metal having high thermal conductivity or a polymer composite material doped with a highly thermally conductive inorganic material such as boron nitride or aluminum nitride, or directly Made of thermal conductive carbon fiber or graphite sheet. However, although the thermal conductivity of the metal is good, but the specific gravity is heavy, it increases the overall weight of the component, and is generally used for blending high thermal conductivity inorganic materials because of thermal conductivity. Restriction (boron nitride: 250~300W/m.K, aluminum nitride 140~180W/m.K), if a predetermined high thermal conductivity (thermal conductivity >300) is to be achieved, the blending ratio of the high thermal conductivity material shall be Extremely high (>50wt%), however, an excessively high proportion of highly thermally conductive inorganic materials can cause a disadvantage of the overall physical properties of the polymer composite.

Accordingly, it is an object of the present invention to provide a method for producing a porous thermally conductive substrate which is lightweight and has high thermal conductivity.

Thus, the method for producing the porous thermally conductive substrate of the present invention comprises: a mixing step, and a foaming step.

The mixing step is to blend a plurality of thermally conductive fibers with a foaming composition to obtain a premix.

The foaming step is to foam the premix to form a porous body having a plurality of pores distributed in the porous body and partially exposed from the pores.

Further, the present invention provides a porous thermally conductive substrate having high thermal conductivity.

Therefore, the porous thermally conductive substrate of the present invention comprises: a porous body having a plurality of pores and a plurality of thermally conductive fibers distributed in the porous body and partially in contact with the outside through the holes, wherein the heat conduction The thermal conductivity of the fiber is between 380 and 2000 W/m. K, and the thermal conductivity of the porous thermally conductive substrate along the direction of its arrangement is not less than 300 W / m. K.

The effect of the invention is to use the heat dispersing fiber to be dispersed in one In the porous body having a plurality of holes, since portions of the heat-conducting fibers are in contact with the outside through the holes, the heat conduction and heat dissipation are excellent, and the porous body has holes, and therefore has Light weight advantage.

2‧‧‧Porous thermal substrate

21‧‧‧Porous ontology

211‧‧‧ hole

212‧‧‧ bottom

213‧‧‧ top surface

22‧‧‧ Thermal Conductive Fiber

100‧‧‧Power components

31‧‧‧Mixed steps

32‧‧‧Foaming step

33‧‧‧Remove steps

4‧‧‧Porous thermal substrate

41‧‧‧Porous ontology

413‧‧‧ top surface

42‧‧‧ Thermal fiber

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a schematic view showing a first embodiment of the porous thermally conductive substrate of the present invention; FIG. 2 is a schematic view. FIG. 3 is a textual flow chart illustrating the preparation method of the first embodiment; FIG. 4 is a schematic view showing the second embodiment of the porous thermally conductive substrate of the present invention; FIG. The preparation method of the second embodiment will be described.

Referring to Figures 1 and 2, the porous thermally conductive substrate 2 of the present invention can be used with a power unit 100 that generates thermal energy, for example, a central processing unit (CPU) inside a general portable electronic component (mobile phone, tablet, etc.). The memory (Memory), the controller (I/O component), the hard disk (HDD), and the like are contacted, and the thermal energy when the power element 100 is activated is derived.

A first embodiment of the porous thermally conductive substrate 2 comprises a porous body 21 and a plurality of thermally conductive fibers 22.

The porous body 21 has a plurality of holes 211, a function of the same The bottom surface 212 of the rate element 100 contacts, and a top surface 213 opposite to the bottom surface 212. In detail, the porous body 21 may be selected from a polymer material suitable for foam molding such as thermosetting or thermoplastic, or a metal or alloy metal which can be used for foaming, wherein the polymer material is selected from epoxy resin. A phenol resin, a furan resin, a polyurethane resin, or the like, and considering the heat dissipation property of the entire porous body 21 after foam molding, preferably, the porous body 21 may be selected from an epoxy resin polymer material having good heat dissipation properties. And the metal or alloy metal may be selected from the group consisting of aluminum (Al), copper (Cu), nickel (Ni), nickel-chromium (NiCrFe) alloy, zinc-copper (ZnCu) alloy, nickel-copper (NiCu) alloy, nickel-chromium Tungsten (NiCrW) alloy, and nickel iron (NiFe) alloy.

The heat conductive fibers 22 are distributed on the porous body 21, and are partially exposed from the holes 211 to be in contact with the outside. The thermally conductive fibers 22 may be distributed to the porous body 21 in a staggered manner or may be arranged in a specific direction and distributed to the porous body 21.

The heat conducting fibers 22 have a maximum contact area with the power element 100 in such a manner that the heat conducting fibers 22 are parallel to the contact surface of the power element 100, and the heat conducting fibers 22 have the most XY plane direction. a good thermal conductivity, therefore, the thermally conductive fibers 22 can quickly direct the heat generated by the power component 100 to the porous thermally conductive substrate 2; and when the thermally conductive fibers 22 are arranged along a power component When 100 is arranged in a substantially vertical direction, since the heat conducting fibers 22 have an optimum thermal conductivity along the longitudinal direction (Z-axis direction), by controlling the arrangement of the heat conducting fibers 22 in the vertical direction, the The thermal energy generated by the power component 100 is quickly directed away from the location of the power component 100.

Specifically, the thermal conductivity of the thermally conductive fibers 22 is between 380 and 2000 W/m. K, the heat conductive fiber 22 suitable for the present embodiment may be selected from a metal fiber, a high thermal conductivity carbon fiber, and a graphitized vapor deposited carbon fiber (Graphitized VGCF), and the porous heat conductive base The thermal conductivity of the material 2 along the direction of arrangement of the thermally conductive fibers 22 is not less than 300 W/m. K. In the present embodiment, the porous thermally conductive substrate 2 shown in Fig. 1 is exemplified by a thermally conductive fiber 22 having staggered distributions as shown in Fig. 2. More preferably, at least a portion of the thermally conductive fibers 22 exposed by the holes 211 are adhered to each other by the polymer material.

In addition, it is to be noted that the holes 211 are formed after foaming, and the purpose is to allow the heat conducting fibers 22 distributed in the porous body 21 to contact the outside by the holes 211, and to alleviate the holes. The volume of the porous body 21 per unit volume, however, although the more the holes 211, the more the area of the heat-conducting fibers 22 in contact with the outside can increase the heat dissipation and the lighter the weight per unit volume, however, the excessive holes 211 will also Since the mechanical strength of the porous body 21 is affected, it is preferable that the density of the porous body 21 is 0.2 to 0.9 g/cm ³ in consideration of heat dissipation, weight, and physical properties as a whole.

When the porous heat conductive substrate 2 is to be used as the heat sink of the power component 100, the bottom surface 212 of the porous body 21 can be directly in contact with the power component 100, as shown in FIG. The thermal energy generated by the component 100 can be rapidly transferred to the porous thermally conductive substrate 2 in contact therewith, and the porous thermally conductive substrate 2 communicates with the outside through the porous thermally conductive substrate 2 The holes 211 allow the heat to quickly escape to the outside, and have better heat conduction and heat dissipation effects.

Preferably, the thermally conductive fibers 22 may be selected from a length of not less than 0.1 mm and a thermal conductivity of not less than 1800 W/m. The graphitized vapor-deposited carbon fiber of K utilizes the high thermal conductivity (thermal conductivity > 1800 W/m.K) of the vapor-deposited fiber, so that heat energy can be more efficiently derived from the electronic component 100, and the use of a larger length The fibers maintain the continuity of the thermal path and allow thermal energy to be more readily derived by the thermally conductive fibers 22.

The preparation method of the first embodiment of the porous thermally conductive substrate 2 described above will be described below.

Referring to FIG. 3, the preparation method of the first embodiment of the present invention comprises: a mixing step 31, and a foaming step 32.

The mixing step 31 is to blend a plurality of thermally conductive fibers 22 with a foaming composition to form a premix.

The foaming composition includes a foaming base, and a foaming agent, and the foaming base may be selected from a polymer, a metal, or an alloy metal. That is, the present invention can be foamed by a polymer matrix or a metal substrate to obtain the porous body 21 composed of a metal or a polymer material.

The polymer composition may be selected from a polymer material suitable for foam molding such as thermosetting or thermoplastic, such as an epoxy resin, a phenol resin, a furan resin, a polyurethane resin, etc., and the porous body 21 after foam molding is considered as a whole. Preferably, the polymer composition may be selected from epoxy resin polymer materials having good heat dissipation; and the metal or alloy metal may be selected from the group consisting of aluminum, copper, nickel, nickel-chromium-iron alloy, zinc-copper. Alloy, nickel-copper alloy, nickel Chromium-tungsten alloy, and nickel-iron alloy.

The foaming composition can generate a gas under a predetermined process condition, so that the foaming matrix forms the holes 211 during the foaming process, and the foaming matrix can be solidified and formed while forming the holes 211. It has predetermined mechanical properties.

It is to be noted that the purpose of the foaming composition described above is to generate a gas under the predetermined process conditions in the subsequent foaming step 32 to form the holes 211, and the foaming step 32 is The material of the foaming matrix is selected, and can be carried out by a polymer foaming or metal foaming process. The polymer foaming can be carried out by physical foaming or chemical foaming. However, chemical foaming is preferred because of the process operability and equipment considerations. Since the related composition, process parameters and control methods of polymer foaming or metal foaming are well known to those skilled in the art, no further explanation will be given.

In detail, the mixing step 31 is performed by pre-arranging the thermally conductive fibers 22 in a desired arrangement and then blending with the foamed composition. That is, when the subsequent heat-conducting fibers 22 are to be arranged in a staggered weave, the interlaced thermally conductive fibers 22 are first laminated in a mold; and when the thermally conductive fibers 22 are arranged in a fixed direction. When the heat-conducting fibers 22 are first laid in a fixed direction in a mold, and then the heat-conducting fibers 22 are obtained to have a structure of interlaced knitting and arranged in a predetermined direction, The staggered woven heat conducting fibers 22 are interleaved with the heat conducting fibers 22 arranged in a fixed direction and mixed with the foaming composition to obtain the premix, and the heat conducting in the premix The fibers 22 are in a predetermined arrangement.

When the porous body 21 composed of a polymer material is subsequently obtained by polymer chemical foaming, the heat-conducting fibers 22 in a predetermined arrangement are laid in the mold, and then the polymer composition containing the polymer composition is used. The high foaming matrix is injected into the mold to wet it and coat the heat conducting fibers 22 to obtain the premix.

When the porous body 21 made of a metal material is to be produced by metal foaming, the heat-conducting fibers 22 in a predetermined arrangement are placed in the mold, and the metal powder and the foaming agent are contained. After the foaming composition is mixed, the premix is obtained.

In this embodiment, polymer chemical foaming is taken as an example for description. Therefore, the foaming composition may include: a polymer foaming matrix, a foaming agent which can be used to generate a gas, and a high foaming property. A hardener for crosslinking and upgrading molecular materials, and a modifier for upgrading.

More specifically, taking an epoxy resin as a foaming substrate as an example, the foaming agent may be selected from the group consisting of azomethicone (AC foaming agent), azobisisobutyronitrile (AZDN), and azoamino group. Benzene, benzenesulfonate (BSH) and p-(p-sulfonate) diphenyl ether (OBSH); the hardener is selected from the group consisting of aliphatic amines, aromatic amines, amidoamines, latent curing amines Class, etc., the modifier can be selected from liquid rubber, flame retardant (inorganic flame retardant, halogen-free flame retardant), surfactant (polyoxyethylene sorbitan laurate, polydimethyl a decane polyoxyalkylene copolymer, an ethylene oxide-propylene oxide block copolymer, a filler (talc, quartz powder, hollow microspheres, etc.), and the composition of the foamed composition and related collocations are generally utilized. When polymer materials are chemically foamed As is known, therefore, no more details are given. In the present embodiment, the polymer composition of the foamed substrate is exemplified by an epoxy resin, and the foamed composition is exemplified by having a hydroquinone, a liquid rubber, and an amine hardener.

The foaming step 32 is to foam the premix so that the foamed substrate forms the porous body 21 having the plurality of pores 211.

Specifically, the foaming step 32 is to heat the premix in the mold to 50 to 180 ° C, and to foam the foamed composition at a predetermined temperature by hot press molding, and at the same time The hardening agent and the modifying accelerator of the foaming composition are subjected to a crosslinking reaction and solidified to obtain the porous thermally conductive substrate 2 as shown in FIG.

Preferably, the premix has a foaming ratio of 2 to 6 times, and the porous body 21 obtained by foaming has a density of 0.4 to 0.9 g/cm ³ .

It should be noted that when the foaming matrix is a metal or an alloy metal, the specific gravity of the porous body 21 obtained after foaming can be regarded as a degree of foaming, and can reach about 2 to 60% of the specific gravity of the parent metal or the alloy metal. For example, foaming is carried out using aluminum metal (2.7 g/cm ³ ) as a foaming substrate to obtain a porous body 21 having a specific gravity of about 0.2 to 0.4 g/cm ³ (a volume of about 13 times that of the parent metal).

Referring to FIG. 4, a second embodiment of the porous thermally conductive substrate 4 of the present invention is substantially the same as the first embodiment except that the thermally conductive fibers 42 of the porous thermally conductive substrate 4 are along a predetermined direction. Arranged and projecting outwardly from the top surface 413 of the porous body 41 away from the power component 100, and directly exposed to the environment. Therefore, the thermal energy of the power element 100 can be more effectively derived.

It should be noted that the heat conducting fibers 22 may also be staggered. The method is distributed to the porous body 41. In this embodiment, the heat conducting fibers 22 are arranged in a predetermined direction as an example, but the arrangement direction is not particularly limited.

Referring to FIG. 5, the manufacturing method of the second embodiment is substantially the same as the manufacturing method of the first embodiment, except that the second embodiment further includes a removing step 33.

The step 33 is to remove a portion of the porous body 41 obtained through the foaming step 32, so that the heat-conductive fibers 42 distributed on the porous body 41 protrude outward from the removed surface, so that The heat dissipation of the porous body 41 can be further improved by direct contact with the outside. For example, the porous body 41 may be removed downward from the surface of the power element 100, so that the heat conductive fibers 42 distributed on the porous body 41 are convex outward from the removed surface (ie, the top surface 413). By stretching, the porous thermally conductive substrate 4 as shown in Fig. 4 can be obtained. Therefore, when the porous thermally conductive substrate 4 is used as the heat dissipating member of the power element 100, the porous thermally conductive substrate 4 can be further extended by the thermally conductive fibers 42 protruding from the porous thermally conductive substrate 4. The absorbed heat is released outside.

Specifically, the removing step 33 may be to remove a predetermined portion of the porous body 41 by sandblasting or laser. It is to be noted that when the removing step 33 is to use a laser to the porous portion When the carbonaceous body 41 is removed by carbonization, not only a predetermined portion of the heat conductive fibers 42 may be exposed, but also carbon particles remaining after the carbonization of the polymer matrix may become a bonding material of the exposed portions of the heat conductive fibers 42. The thermally conductive fibers 42 are bonded to each other so that the bare portions of the thermally conductive fibers 42 are less likely to fall.

In summary, the present invention utilizes the incorporation of thermally conductive fibers 22, 42 with a foamable foaming composition to provide a porous thermally conductive substrate 2, 4 that is porous and has a distribution of thermally conductive fibers 22, 42. Since portions of the heat-conducting fibers 22 and 42 are in contact with the outside through the holes 211, they have excellent heat conduction and heat dissipation, and the porous bodies 21 and 41 have light holes. The advantages are indeed achieved by the object of the invention.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

2‧‧‧Porous thermal substrate

21‧‧‧Porous ontology

211‧‧‧ hole

212‧‧‧ bottom

213‧‧‧ top surface

100‧‧‧Power components

Claims (13)

A method for manufacturing a porous thermally conductive substrate, comprising: a mixing step of blending a plurality of thermally conductive fibers with a foaming composition to form a premix; and a foaming step of foaming the premix Forming the foamed composition into a porous body having a plurality of pores, the thermally conductive fibers being distributed over the porous body and partially exposed from the holes; and a removing step of removing at least the porous body In part, the heat-conducting fibers are exposed to the outside environment. The method for producing a porous thermally conductive substrate according to claim 1, wherein the foaming composition comprises a foaming substrate and a foaming agent, and the foaming substrate may be selected from the group consisting of a polymer, a metal, or an alloy metal. The method for producing a porous thermally conductive substrate according to claim 2, wherein the polymer is one selected from the group consisting of an epoxy resin, a phenol resin, a furan resin, and a polyurethane resin. The method for producing a porous thermally conductive substrate according to claim 2, wherein the metal or alloy metal is selected from one of the group consisting of aluminum, copper, nickel, nickel-chromium-iron alloy, zinc-copper alloy, nickel-copper alloy, and nickel. Chromium-tungsten alloy, and nickel-iron alloy. The method for producing a porous thermally conductive substrate according to claim 1, wherein the highly thermally conductive fibers are distributed in a staggered manner to the porous body. The method for producing a porous thermally conductive substrate according to claim 1, wherein the isothermally thermally conductive fibers are arranged in one direction in the porous portion. body. The method for producing a porous thermally conductive substrate according to claim 1, wherein the high thermal conductivity fiber is selected from the group consisting of a thermal conductivity of 380 to 2000 W/m. K fiber. The method for producing a porous thermally conductive substrate according to claim 7, wherein the constant thermally conductive fibers are selected from the group consisting of metal fibers, highly thermally conductive carbon fibers, or graphitized vapor deposited carbon fibers. A porous thermally conductive substrate comprising a porous body having a plurality of pores and a plurality of thermally conductive fibers distributed on the body and partially in contact with the outside via the holes and from at least a portion of the surface of the porous body External convex protrusion, wherein the thermal conductivity of the thermal conductive fibers is between 380 and 2000 W/m. K, and the thermal conductivity of the porous thermally conductive substrate along the direction of its arrangement is not less than 300 W / m. K. The porous thermally conductive substrate according to claim 9, wherein the porous body has a base surface, and the heat conductive fibers are arranged in a direction perpendicular to the base surface. The porous thermally conductive substrate according to claim 9, wherein the thermally conductive fibers are staggered to distribute the porous body. The porous thermally conductive substrate according to claim 9, wherein the porous body is made of a polymer material, and at least a part of the heat conductive fibers are bonded to each other by the polymer material. The porous thermally conductive substrate of claim 9, wherein the isothermally thermally conductive fibers are selected from the group consisting of metal fibers, highly thermally conductive carbon fibers, or graphitized vapor deposited carbon fibers.