TW201943556A - Metal-carbon composite foil heat sink and method of manufacturing the same - Google Patents

Abstract

The present invention provides a metal-carbon composite foil heat sink including a metal foil and coarsening layers at both sides of the metal foil, wherein holes are uniformly distributed on the surface of coarsening layer. A sputtered carbon layer is coated on the coarsening layer, and a rolled carbon layer is formed on and bonded with the sputtered carbon layer. The rolled carbon layer is fixed on the coarsening layer in an embedded manner through the holes.

Description

Metal-carbon composite thermally conductive foil and manufacturing method thereof

The present invention relates generally to a thermally conductive foil, and more specifically, it relates to an improved metal-carbon composite thermally conductive foil with improved thermal conductivity and a method for manufacturing the same.

With the rapid development of the electronics industry, electronic devices in modern society are becoming more and more popular, such as personal computers, mobile phones, business machines, GPS navigation devices and other electronic devices, and the volume of electronic components and electronic devices is now increasingly thin, light, In the small direction, in addition to being thin, light, and small, functions have become more and more powerful. With the increasing integration of electronic products, the number of electronic components in a unit area has increased geometrically. Heat conduction has become a very important issue. If the heat is not dissipated in time, it will cause the component operating temperature to rise. Will make electronic components fail, directly affect the life and reliability of various high-precision equipment using them. Therefore, how to efficiently conduct heat has become the bottleneck of miniaturization and integration of electronic products.

Generally, the traditional technology for heat conduction is the use of thermal conductive silicone. The advantage of thermal conductive silicone is that it is compressible. However, compared to copper and other metals, thermal conductive silicone is too slow to conduct heat, and it is usually equipped with a fan. When fast temperature reduction is required, space is limited. It seems helpless. Therefore, it is considered by industry practitioners that a carbon layer is bonded to the bottom of copper to achieve thermal conductivity. Although the carbon composite thermal conductive foil with a carbonaceous substance attached to the bottom surface of the copper foil can effectively improve the thermal conductivity, the carbonaceous substance constituting the carbon layer is more unstable between the bonding with the heterogeneous copper foil and is easily peeled off from the surface of the copper foil. In addition, due to the heterogeneous relationship between metal and carbon, its heat conduction effect cannot be further improved. Furthermore, an excessively thin carbonaceous material cannot actually achieve an effective heat conduction effect, but a thicker carbonaceous material cannot be effectively fixed on a copper foil. These are the problems encountered in actual production. Therefore, the industry still needs to improve the existing thermal copper foil technology in order to obtain products with more stable structure and better thermal conductivity.

The reason is that the present inventor has taken into account the many defects in the existing carbon composite thermal conductive foil, such as the poor bonding between the carbon layer and the metal material, and the insufficient thermal conductivity, which is supplemented by his many years of manufacturing and design experience and knowledge in related fields, After various ingenuity, the structure and manufacturing method of the existing carbon composite heat-conducting foil were updated, researched, developed and improved. The invention combines the dual advantages of strong adhesion of sputtered carbon and large thickness of rolled carbon and low cost.

An object of the present invention is to provide a metal-carbon composite heat-conducting foil, which includes: a metal substrate having roughened layers on both sides thereof, the roughened layer having evenly distributed holes on the surface thereof, and a sputtered carbon layer formed on the roughened layer. A forming layer and a rolled carbon layer are formed on the sputtered carbon layer and bonded to the rolled carbon layer, and are engaged with the roughened layer through the holes.

Another object of the present invention is to provide a method for manufacturing a metal-carbon composite thermally conductive foil. The steps include: providing a metal substrate, and roughening both sides of the metal substrate to generate a roughened layer, wherein the roughening is performed. Holes are evenly distributed on the surface of the layer, and a sputtering process is performed to form a sputtered carbon layer on the surface of the roughened layer. The carbon material attached to the release film is laid on both sides of the metal substrate and a rolling process is performed. , So that a part of the carbon material is pressed into the holes of the roughened layer, so that a rolled carbon layer is formed on the sputtered carbon layer and is bonded with it, and the roughened layer is engaged with each other through the holes.

These and other objects of the present invention will certainly become more apparent after the reader has read the detailed description of the preferred embodiments described in various figures and drawings below.

In the following detailed description of the present invention, the component symbols will be marked as part of the accompanying drawings, and will be represented in a special description manner that can implement this embodiment. Such an embodiment would illustrate enough details to enable a person of ordinary skill in the art to implement it. For the sake of clarity, the thickness of some components in the illustration may be exaggerated. The reader must understand that other embodiments can also be used in the present invention, or structural, logical, and electrical changes can be made without departing from the described embodiments. Therefore, the following detailed description is not intended to be regarded as a limitation. On the contrary, the embodiments included therein will be defined by the scope of the accompanying patent application.

First, please refer to Figure 1. At the beginning of the manufacturing process, a metal substrate 100, such as a rolled copper foil or rolled aluminum foil, is provided. Its thickness can be between about 25 μm (microns) to 100 μm, and it is about 200- 400W / mK (Watts per milligram) Good thermal conductivity. The metal substrate 100 can be made into any shape, which is convenient for use in different products. Foil has the advantages of flexibility, light weight, and low cost. It is also easy to process for processing. Since the metal substrate 100 is in contact with air, hands, and other transportation tools during storage and transportation, it is susceptible to contamination by oils and salinities, so it should be treated with a neutral degreaser and neutral detergent first. Before you can roughen it.

Refer to Figure 2 next. After the pre-cleaning treatment, the surface of the metal base material 100 is subjected to a roughening treatment to form roughened layers 100 a on both sides of the base material. In the embodiment of the present invention, the roughened layer 100a is formed by forming uniformly distributed holes 102 on the surface of the metal substrate 100. The metal substrate 100, the roughened layer 100a, and the holes 102 are integrated structures. Generally, the roughening treatment of the metal surface in the industry generally adopts the anodizing method or the sand blasting method. However, in the embodiment of the present invention, in order to generate holes with a greater depth to achieve a higher specific volume, The roughening step uses a chemical acid tank treatment. For example, the surface of the metal substrate subjected to sandblasting treatment is sent to the acid tank. The surface roughening acid etchant is added and ultrasonic treatment is performed to further expand the original pores. Holes 102 are uniformly distributed on the surface of the material 100, and the depth can reach about 1.5 μm to 10 μm. In the embodiment of the present invention, the hole structure with a large depth and a high specific volume value will help improve the degree of fitting of the subsequent carbon thermal conductive material and the metal substrate 100. It should be noted that the aforementioned pre-treatment step can also be integrated in this chemical acid tank step, and the metal substrate may have holes formed on only one side.

Then refer to Figure 3. After the roughened layer 100a is formed on the metal substrate 100, a sputtering process is next performed to form a sputtered carbon layer 104 on the roughened layer 100a. In the embodiment of the present invention, the sputtering process is a vacuum magnetron sputtering process, which can form a uniformly conformal, high-density sputtered carbon layer 104 on the surface of the roughened layer 100a. Between 100nm (nano) to 300nm. The target material used in this sputtering process can be carbon materials such as artificial graphite, graphene, nano carbon, or nano carbon tube. The carbonaceous target material will be impacted by high-energy charged particles during the sputtering process to cause carbon atoms to splash. It is ejected and finally deposited on the metal substrate 100 to form a sputtered carbon layer 104, such as a carbon cluster film that is bonded to form a two-dimensional layered structure or a three-dimensional three-dimensional structure. In the embodiment of the present invention, the reason why the thin carbon layer is first formed on the metal roughened layer 100a by the sputtering process is that the sputtered carbon layer 104 formed thereon has extremely high density, which is beyond the reach of other processes. Therefore, it can be adhered to the metal substrate 100 very tightly, and it is not easy to fall off, and its nanometer thickness does not affect the hole depth and the high specific volume of the roughened layer 100a formed previously. The above-mentioned sputtering process can be performed on both sides at the same time, or turned over again after a single operation.

Then refer to Figure 4. After the thin sputtered carbon layer 104 is formed on the roughened layer 100a, another carbon material, such as artificial graphite, graphene, nanocarbon, or nanocarbon tube, is then tiled on both sides of the metal substrate 100. To prepare for the calendering step, such as the rolling step. In this step, the carbon material can be uniformly distributed, flattened, and fixed on a release film, and the thickness of the carbon material is about 100-200 μm, which provides a basis for the subsequent rolling step. After the carbon material is prepared, a rolling process is performed, and a part of the carbon material is pressed into the holes 102 of the roughened layer 100a, so that a rolled carbon layer 106 is formed on the sputtered carbon layer 104. In order to improve the bonding strength between the carbon material and the roughened layer 100a and allow the pressed carbon material to fill the holes 102, a staged rolling mode may be adopted in the manufacturing process, that is, multiple rolling operations with increasing pressure are performed. The first time pressing of the carbon material enters the hole 102. At this time, the pressure is not great, but it is just a squeezing action to play the role of filling and squeezing. The second rolling improves the density of the rolled carbon material to about 0.4 to 0.5 g / cm3 (g / cm3). At this time, it is still rough pressing, and there is no special requirement for accuracy. After multiple rolling, the density of the carbon material will increase to about 1.2 to 1.4 g / cm3. At this time, the rolled carbon layer 106 has been completely formed into a film, and has thermal conductivity and a large thermal conductivity. The subsequent rolling will make the density of the rolled carbon layer 106 reach 1.6 to 1.8 g / cm3, or even higher. At this time, the rolled carbon layer 106 on both sides of the metal substrate has metallic luster, the thermal conductivity reaches its peak, and the thermal diffusion coefficient also tends to stable. More importantly, the rolled carbon layer 106 will bond with the adjacent homogeneous sputtered carbon layer 104 after multiple rolling steps. This is why the present invention uses a sputtering process to form a thin sputtered carbon layer 104 before performing the rolling step, because a homogeneous carbon layer is liable to bond under pressure, which is different from directly rolling the carbon layer 106. Press on the heterogeneous metal substrate 100. Because the natural carbon material is formed by bonding carbon atoms, the rolled carbon layer itself has excellent adhesion and is not easy to fall off from each other, and the high-purity carbon material has better conductivity and electrical conductivity. Nano-grade carbon material is evenly distributed on the metal substrate, and heat conduction is performed by high thermal conductivity, and then the thermal energy is converted into infrared radio frequency by the high radiation efficiency of carbon atoms, thereby effectively conducting heat. In addition to bonding, the pressed carbon layer 106 will intersect with the roughened layer 100a through the holes 102, and further fix the rolled carbon layer 106 on the roughened layer 100a. The thickness of the rolled carbon layer 106 after rolling may be between about 30 μm and 100 μm. This rolling step can also be performed in a temperature-raised environment to further improve the bondability between the rolled carbon layer 106 and the sputtered carbon layer 104.

In the embodiment of the present invention, the application of the rolled carbon layer 106 can improve the problem that the thermal conductivity of the simple sputtering carbon layer 104 is not good because the thickness is too thin, and the homogeneous carbon layers are bonded to each other. It is known that the problem that the rolled carbon layer 106 is easily detached from the metal substrate can also be effectively solved, which is an excellent process improvement method. It should be noted that in the present invention, the metal substrate may be rolled on only one side to form a rolled carbon layer.

Please refer to FIG. 5, which illustrates a schematic cross-sectional view of a metal-carbon composite thermally conductive foil according to another embodiment of the present invention. In the case where the metal substrate 100 is a rolled aluminum foil, in order to improve the thermal conductivity of the aluminum material, another sputtering process may be performed before the sputtering process to form the sputtered carbon layer 104, and the roughening of the layer 100a may be performed first. A material layer having a higher thermal conductivity than the aluminum material is formed on the surface, such as a sputtered copper layer 108, and then the sputtered carbon layer 104 is formed on the sputtered copper layer 108. The thickness of the sputtered copper layer 108 may be similar to that of the sputtered carbon layer 104, and is between about 100 nm and 300 nm. Since the thermal conductivity of copper is better than aluminum, sputter plating a copper layer on an aluminum substrate will help improve the thermal conductivity of the overall composite thermal foil. The subsequent process is as described above. Sputtered carbon layer 104 is sputtered on the sputtered copper layer 108, and then multiple rolling steps are performed to form a bond with the sputtered carbon layer 104 and fit into the roughened layer 100a. The rolled carbon layer 106 thus completes the production of the metal-carbon composite thermally conductive foil. The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the scope of patent application of the present invention shall fall within the scope of the present invention.

100‧‧‧ metal substrate

100a‧‧‧roughened layer

102‧‧‧ Hole

104‧‧‧Sputtered carbon layer

106‧‧‧Rolled carbon layer

108‧‧‧Sputtered copper

This specification contains drawings and constitutes a part of this specification in the text, so that readers have a further understanding of the embodiments of the present invention. These illustrations depict some embodiments of the invention and together with the description, explain the principles. In the drawings: FIGS. 1-4 are schematic cross-sectional views illustrating a manufacturing process of a metal-carbon composite thermally conductive foil according to an embodiment of the present invention; and FIG. 5 is a schematic diagram illustrating another embodiment of the present invention. Cross-section schematic diagram of metal-carbon composite heat-conducting foil; please note that all the illustrations in this specification are for illustrative purposes. For clarity and convenience of illustration, the components in the illustration may be exaggerated in size and proportion. In a reduced scale, generally speaking, the same reference symbols in the figures will be used to indicate corresponding or similar element features in the modified or different embodiments.

Claims (11)

A metal-carbon composite heat-conducting foil comprises: a metal substrate having roughened layers on both sides of the metal substrate, wherein holes are evenly distributed on the surface of the roughened layer; a carbon layer is sputtered and formed on the roughened layer And a rolled carbon layer formed on the sputtered carbon layer and bonded to the rolled carbon layer and engaged with the roughened layer through the holes. The metal-carbon composite thermally conductive foil according to item 1 of the scope of the patent application, wherein the metal substrate, the roughened layer, and the holes are an integrated structure. The metal-carbon composite thermally conductive foil according to item 1 of the scope of the patent application, wherein the metal substrate is a rolled copper foil or a rolled aluminum foil. The metal-carbon composite thermally conductive foil according to item 1 of the scope of the patent application, wherein the metal substrate is a rolled aluminum foil, and further includes a sputtered copper layer formed between the roughened layer and the sputtered carbon layer. According to the metal-carbon composite thermally conductive foil described in item 4 of the patent application scope, the thicknesses of the sputtered copper layer and the sputtered carbon layer are 100 nm (nanometer) to 300 nm. According to the metal-carbon composite thermal conductive foil described in item 1 of the scope of the patent application, wherein the thickness of the metal substrate is 25 μm (micrometer) to 100 μm, and the depth of the holes is 1.5 μm to 10 μm, and the thickness of the sputtered carbon layer The thickness is 100 nm to 300 nm, and the thickness of the rolled carbon layer is 30 μm to 100 μm. The metal-carbon composite thermally conductive foil according to item 1 of the scope of the patent application, wherein the material of the sputtered carbon layer and the rolled carbon layer is artificial graphite, graphene, nano carbon, or nano carbon tube. A method for manufacturing a metal-carbon composite heat-conducting foil, comprising: providing a metal substrate; roughening both sides of the metal substrate to produce a roughened layer, wherein holes are evenly distributed on the surface of the roughened layer; The plating process forms a sputtered carbon layer on the surface of the roughened layer; the carbon material attached to the release film is flattened on both sides of the metal substrate and a rolling process is performed, so that part of the carbon material is pressed in In the holes of the roughened layer, a rolled carbon layer is thus formed on the sputtered carbon layer and bonded to it, and the roughened layer is engaged with each other through the holes. The method for manufacturing a metal-carbon composite thermally conductive foil as described in item 8 of the scope of the patent application, wherein the metal substrate is a rolled aluminum foil, and further includes performing another sputtering process before forming the sputtered carbon layer. A sputtered copper layer is formed on the surface of the roughened layer, and then the sputtered carbon layer is formed on the sputtered copper layer. The method for manufacturing a metal-carbon composite thermally conductive foil as described in item 8 of the scope of application for patent, wherein the roughening treatment is a chemical acid tank treatment step. The method for manufacturing a metal-carbon composite thermally conductive foil according to item 8 of the scope of the patent application, wherein the roughening treatment includes a surface pretreatment of the metal substrate and a cleaning treatment after the roughening.