JP7585384B2 - Graphene metal composite material, target and electromagnetic wave prevention package parts - Google Patents

Description

The present invention relates to a graphene metal composite material, and in particular to a graphene metal composite material and a target and an electromagnetic wave protection package part made therefrom.

As electronic components become smaller and require higher output, higher frequency, and lower power consumption, there are an increasing number of situations where conventional materials are unable to meet these demands.

When commonly used conductive materials such as copper, gold, and silver are used as wires to meet the demands of miniaturization, their diameters must be made smaller. However, the smaller the diameter, the higher the electrical resistance, so there is already a limit to how much the diameter can be reduced without affecting electrical conductivity and physical properties.

And because graphene has excellent mechanical properties, thermal conductivity and electrical conductivity, it is widely used as a reinforcing material in composite materials for strength enhancement, electrical conductivity or thermal conductivity.

However, due to its structure, the layers of graphene are bound together vertically by van der Waals forces, and graphene has poor compatibility with metals, making it difficult to disperse the reinforcing material, graphene, in metal. Therefore, dispersing graphene is one of the challenges in graphene-metal composite materials.

For example, Patent Document 1 discloses a method for dispersing graphene in copper, and Patent Document 2 discloses a method for dispersing graphene in aluminum.

Chinese Patent No. 105908007 Chinese Patent Publication No. 105112699

The present invention provides a graphene metal composite material with excellent dispersibility.

In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor device comprising the steps of:
the plurality of graphene sheets are dispersed and arranged among the crystal lattice of the metal, and at least some of the graphene sheets are bonded together by covalent bonds;
Overall,
The oxygen content is less than 10 ppm.
The present invention provides a graphene metal composite material, characterized in that the graphene content is 3 wt % or less, with the total weight being 100 wt %.

The present invention also provides a target that is characterized by being composed of the above-mentioned graphene metal composite material.

The present invention also provides a semiconductor device comprising: a substrate having an electric circuit;
an electronic component disposed on the substrate so as to be electrically connected to the substrate;
an encapsulant layer encapsulating the electronic component;
an electromagnetic wave prevention layer made of the graphene metal composite material;
and a protective layer made of stainless steel.

With the above configuration, the graphene metal composite material of the present invention is composed mainly of multiple graphene sheets and metal, the multiple graphene sheets are dispersed and arranged among the crystal lattice of the metal, and at least some of the graphene sheets are bonded together by covalent bonds. The oxygen content in the entire material is 10 ppm or less, so the graphene metal composite material of the present invention has few structural defects and excellent stability, and therefore has excellent electrical conductivity, excellent oxidation resistance, and excellent electromagnetic wave prevention effect.

As a result, a target made of the graphene metal composite material of the present invention can be used to form a coating film that is resistant to oxidation and has high electrical conductivity, and an electromagnetic wave protection package part made of the graphene metal composite material of the present invention has a simple manufacturing process and excellent electromagnetic wave protection effect.

1A and 1B are diagrams showing an embodiment of an electromagnetic wave protection package part of the present invention. 1 is a graph showing the electromagnetic shielding effectiveness (SE) of an electromagnetic wave protection package component at different frequencies.

The following describes in detail an embodiment of the present invention with reference to the drawings.

The graphene metal composite material of the present invention is essentially composed of multiple graphene sheets and metal, i.e., is composed mainly of multiple graphene sheets and metal.

The graphene sheets are arranged in a dispersed manner among the crystal lattice of the metal, and at least some of the graphene sheets are bonded together by covalent bonds, and at least some of the graphene sheets are bonded to the metal.

The graphene metal composite material has an oxygen content of 10 ppm or less, and the graphene content is 3 wt% or less, with the total weight being 100 wt%.

The metal is copper (Cu), aluminum (Al), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), or tin (Sn).

Since the specific gravity of graphene is very small, if the graphene content in a graphene metal composite exceeds 3 wt%, the graphene aggregates and becomes difficult to disperse, and if the graphene content is too low, the effect of strengthening the composite material is not easily achieved.

Preferably, the graphene content is in the range of 0.02 wt% to 0.5 wt% when the total weight of the graphene metal composite material is 100 wt%, and more preferably, the graphene content is in the range of 0.02 wt% to 0.3 wt% when the total weight of the graphene metal composite material is 100 wt%.

The thermal conductivity of the graphene metal composite material is 460 W/mK or more.

The method for producing the graphene metal composite material of the present invention is described below.

First, step A is performed. In step A, a metal powder, a modified graphene powder, and a binder are mixed to obtain a composite powder raw material.

The metal powder can be a powder of a metal such as copper, aluminum, gold, silver, platinum, palladium, or tin.

The modified graphene powder contains multiple graphene sheets that have been surface-modified.

The amount of modified graphene powder added is in the range of 0.02% to 3% of the weight of the metal powder added.

The groups used to modify the surface of graphene can be groups containing functional groups such as oxygen, nitrogen, etc.

In some embodiments, the group is selected from fatty acids, such as stearic acid.

The amount of adhesive added ranges from 0.1% to 10% of the weight of the modified graphene powder added.

The adhesive contains, with its total weight being 100 wt%, 5 wt% to 20 wt% of dispersant, 0.5 wt% to 2 wt% of coupling agent, and the remainder being wax or low molecular weight thermoplastic polymer.

The dispersant can be methylpentanol, polyacrylamide, or polyethylene glycol fatty acid.

The coupling agent is selected from a titanic acid ester or an organic chromium compound.

The wax may be paraffin or microcrystalline wax.

The low molecular weight thermoplastic polymer may be acrylic, etc.

Titanate esters and organic chromium compounds have strong bonding force with surrounding electrons, and titanate esters have the advantage of being lightweight, while organic chromium compounds (organic chromium coordination compounds) have side chains, allowing more bonding to be formed.

Therefore, an appropriate coupling agent (titanate ester or organic chromium compound) can be selected as needed, and the bonding strength between the modified graphene powder and the metal powder can be enhanced, and bonding can occur between at least a portion of the graphene and the metal.

Dispersants and waxes can improve the dispersion of the modified graphene and the stabilization of the modified graphene after dispersion.

To explain in more detail, in step A, the metal powder, the modified graphene powder, and the adhesive are mixed by a method such as kneading, a planetary stirrer, or a planetary ball mill, and heat capable of breaking the bond between the graphene and the group used for surface modification of the graphene is generated during mixing, so that the bond between the group used for surface modification and the graphene absorbs heat during mixing, and then the bond is broken, and the group used for surface modification is detached from the graphene.

In addition, carbon atoms in graphene where bonds have been broken can bond with carbon atoms in other graphene where bonds have been broken, and the coupling agent promotes bonding between the graphene where bonds have been broken and the metal powder, so that at least some of the graphene are connected to each other in a planar manner and wrap the metal powder in multiple layers to form a composite powder raw material.

Then, step B is carried out. In step B, the composite powder raw material is placed in a mold, and the metal powders in the composite powder raw material are melted and combined into a single metal body by a vacuum hot pressing sintering method, and at least a part of the graphene is bonded within the metal body in a three-dimensional network shape by covalent bonds. At the same time, the adhesive, the detached organic substances such as the groups used for surface modification are vaporized and removed at the high temperature of sintering, and a semi-finished graphene metal composite material is obtained.

The temperature for vacuum hot press sintering can be varied depending on the type of metal powder, and since sintering is performed under pressure and vacuum conditions, sintering can be performed at a lower temperature.

In an example where the metal powder is copper powder, step B can involve vacuum hot press sintering at 700°C.

Graphene does not melt and has a boiling point much higher than the boiling points of the metals and organics, so it is not destroyed during sintering, while most of the organic impurities (e.g., groups used to modify the graphene surface, adhesives, etc.) are vaporized and removed.

The graphene metal composite semi-finished product obtained in step B therefore contains substantially only graphene and metal. Moreover, the graphene is uniformly dispersed in the metal body.

Each carbon atom of graphene forms a honeycomb-like hexagonal lattice structure through its own ^sp2 bond to form a sheet. After sintering, the graphene is dispersed and arranged among the atoms of the metal crystal lattice, and at least some of the graphene is bonded together by covalent bonds, resulting in a semi-finished graphene metal composite material with high stability.

Then, step C is performed. In step C, the graphene metal composite semi-finished product is vacuum smelted to obtain the graphene metal composite.

After steps A and B have been performed, the graphene that is not bonded to other graphene or to the metal is randomly dispersed in the semi-finished graphene metal composite material. Therefore, by melting the semi-finished graphene metal composite material by vacuum smelting to make it liquid, the randomly dispersed graphene can be uniformly dispersed in the metal.

In addition, metal oxides present as impurities in the metal powder can be reduced to metal by vacuum smelting, so the oxygen content of the final graphene metal composite material can be 10 ppm or less.

The graphene metal composite material produced by the manufacturing method of the present invention is composed mainly of multiple graphene sheets and metal, and has superior thermal conductivity and electrical conductivity to the original metal material, and also has particularly excellent oxidation resistance.

In this embodiment, vacuum smelting is performed under conditions of heating to 1300°C in a nitrogen atmosphere.

In addition, since the metal oxides in the metal powder are further reduced during vacuum smelting, the metal raw material used in the present invention does not need to be a high-purity oxygen-free metal (e.g., oxygen-free copper), and the graphene metal composite material of the present invention can be obtained using ordinary metals as raw materials.

Furthermore, in the method for producing a graphene metal composite material of the present invention, step B' can be carried out before step B. In step B', wax is removed at a low temperature to obtain a dewaxed semi-finished product. The graphene metal composite material of the present invention can also be obtained by subjecting the dewaxed semi-finished product to steps B and C.

In more detail, in step B', the composite powder raw material obtained in step A is heated to form the composite powder raw material into a liquid mixed material. The liquid mixed material is then placed in a mold and solidified into a green body by cold forming. A debinding process is then performed on the green body to remove the adhesive in the green body and form it into a dewaxed semi-finished product.

More specifically, the debinding process involves heat-treating the base material by thermal dewaxing at 140°C to 170°C. In this thermal dewaxing process, an inert gas is used as a flow medium to heat the base material, causing the adhesive in the base material to undergo pyrolysis and vaporize, and the adhesive is then removed from the base material by the flow medium, resulting in the dewaxed semi-finished product.

The temperature of the heat treatment for thermal dewaxing is preferably lower than the melting point of the metal powder and higher than the melting point or boiling point of the adhesive. When heated to 140°C to 170°C, graphene does not melt and its boiling point is much higher than the boiling points of the metal and the adhesive, so the structure is not destroyed during the heat treatment.

The graphene metal composite material of the present invention can be made into wires or films, or used as a coating target to form a conductive coating film that is resistant to oxidation and has high electrical conductivity, making it applicable to a variety of fields.

Hereinafter, the characteristics of the graphene metal composite material of the present invention will be described with reference to each specific example and comparative example.
In a specific example, a graphene copper composite was produced by the above-mentioned method for producing a graphene metal composite using 100 g (100 wt %) of copper powder (Mitsui Kinzoku Ato Co., Ltd., model number: MA-CC-S) and 3 g (3 wt % of the weight of the copper powder) of modified graphene powder (EnerAge Inc., Taiwan, model number: P-PG20).

The graphene copper composite of the specific example was measured using an oxygen, nitrogen and hydrogen analyzer (model: EMGA 930) according to ASTM E2575-19, and the oxygen content of the graphene copper composite was found to be 6.0 ppm, which is much lower than the oxygen content of oxygen-free copper (OFC) (less than 0.003%).
Comparative Example In the comparative example, a graphene copper composite material was produced by carrying out only steps A and B of the above-mentioned graphene metal composite material production method using 100 g (100 wt %) of copper powder (Mitsui Kinzoku Ato Co., Ltd., model number: MA-CC-S) and 3 g (3 wt % of the weight of the copper powder) of modified graphene powder (EnerAge Inc., Taiwan, model number: P-PG20).

The graphene copper composite materials of the specific examples and comparative examples were rolled into sheets of 100 mm x 60 mm x 0.2 mm (length x width x thickness), and the electrical conductivity (% IACS) was measured at five points (T1 to T5) on the surface of each sheet. The electrical conductivity measurement results are shown in Table 1.

The electrical conductivity (%IACS) was calculated using the formula (σ/58.0 x 100%), with the electrical conductivity of the internationally adopted annealed standard soft copper set at 100% IACS (international annealed copper standard). σ is the volume resistivity.

According to the results in Table 1, compared with the general graphene metal composite material obtained by sintering in step B, the graphene metal composite material of the present invention obtained by smelting in step C not only has a better electrical conductivity but also has a better uniformity of electrical conductivity.

Table 2 shows the electrical conductivity, break strength (BS), elongation strength, Young's modulus, yield strength, ultimate tensile strength (UTS), toughness, and maximum load of 1.2 mil diameter wires made from commercially available 6N OFC (oxygen-free copper) and the specific example graphene metal composite (represented as G-Cu in Table 2).

The graphene metal composite material of the specific example was then made into wires of different diameters, and the resistance, break load, elongation, tensile strength, and electrical conductivity of each wire were measured. The measurement results are shown in Table 3.

As shown in Table 2, under the same diameter length conditions, the electrical conductivity of the wire made from the specific example graphene metal composite material was clearly superior to the electrical conductivity of the wire made from pure copper (6N OFC).

As shown in Table 3, the wire made from the graphene metal composite of the specific example has a higher electrical conductivity as the diameter length is smaller, and when the diameter length is 0.05 mm or less, the electrical conductivity is higher than that of silver (105% IACS), which indicates that the graphene metal composite of the present invention has excellent electrical conductivity.

In addition, the following examples will explain how the graphene metal composite material of the present invention can be used to create electromagnetic wave protection packaging components that can block electromagnetic waves.

As shown in FIG. 1, the electromagnetic wave protection package component includes a substrate 31, an electronic component 32 mounted on the substrate 31 so as to be electrically connected to the substrate 31 by a wire 321, a sealant layer 33 encasing the electronic component 32, an electromagnetic wave protection layer 34 formed to cover the sealant layer 33, and a protective layer 35 covering the electromagnetic wave protection layer 34.

Substrate 31 is a circuit board having an electrical circuit.

The sealant layer 33 is made of a polymeric material, such as an epoxy resin.

The electromagnetic wave prevention layer 34 is made of the graphene metal composite material of the present invention, and in this embodiment, the electromagnetic wave prevention layer 34 is made of the graphene metal composite material of the specific example above.

The protective layer 35 is made of stainless steel. FIG. 2 is a graph showing the results of measurements of the electromagnetic shielding effectiveness (SE) of an electromagnetic wave protection package component at different frequencies.

The electromagnetic shielding effectiveness (unit: dB) is defined as follows:

After an incident wave (b) is shielded by a material, a portion of it becomes a transmitted wave (a). In this case, the electromagnetic shielding effectiveness (SE) of the material is calculated by the following formula:
SE=10×log(Pb/Pa)
P: energy field strength (Watts/m).

As shown in FIG. 2, Example 1 uses a graphene metal composite material to form an electromagnetic wave prevention layer 34, and has the structure of the electromagnetic wave prevention package part shown in FIG. 1 (sealant layer 33/electromagnetic wave prevention layer 34 (4 μm)/stainless steel protective layer 35 (0.6 μm)).

Example 2 is similar to Example 1, except that it further has a stainless steel intermediate layer between the sealant layer 33 and the electromagnetic wave prevention layer 34 (sealant layer 33/stainless steel intermediate layer (0.6 μm)/electromagnetic wave prevention layer 34 (4 μm)/stainless steel protective layer 35 (0.6 μm)).

Comparative Example 1 is similar to Example 2, except that the electromagnetic wave prevention layer 34 is made of pure copper.

Since the adhesion between pure copper and the sealant layer 33 is poor, in the prior art, when pure copper is used as an electromagnetic wave blocking material, it is necessary to form a stainless steel intermediate layer on the sealant layer 33 as an intermediate material between the sealant layer 33 and the pure copper electromagnetic wave blocking layer 34 before forming the pure copper electromagnetic wave blocking layer 34 on the sealant layer 33, and then form the pure copper electromagnetic wave blocking layer 34 on the stainless steel intermediate layer, and further form a stainless steel protective layer 35 on the pure copper electromagnetic wave blocking layer 34. The structure of Comparative Example 1 was obtained in this way.

In contrast, when the graphene metal composite material of the present invention is used as the electromagnetic wave prevention layer 34, the graphene can increase the affinity with the polymer material, improving the adhesion between the electromagnetic wave prevention layer 34 and the sealant layer 33. This means that the electromagnetic wave prevention layer 34 can be formed directly on the sealant layer 33, eliminating the need to form the stainless steel intermediate layer as in the conventional technology, and simplifying the manufacturing process.

Furthermore, according to FIG. 2, the electromagnetic wave blocking effect of Examples 1 and 2 is superior to that of Comparative Example 1, and the electromagnetic wave shielding effect of Example 1 at 6 GHz is greater than 70 db, far superior to the 30 db of Comparative Example 1.

In other words, a package structure made using the graphene metal composite material of the present invention as the electromagnetic wave blocking layer 34 can omit the stainless steel intermediate layer from the conventional structure, can be constructed thinner, and has a better electromagnetic wave blocking effect.

According to the above, the graphene metal composite material of the present invention can be obtained by further performing vacuum smelting, so that the graphene can be more uniformly dispersed in the metal, and the properties of the graphene metal composite material are improved.

In addition, during the vacuum smelting process, the metal oxides in the metal powder are reduced to metal, so that the oxygen content of the graphene metal composite material of the present invention can be 10 ppm or less, which can reduce structural defects of the graphene metal composite material, improve the electrical conductivity, thermal conductivity and other properties of the graphene metal composite material, and provide better oxidation resistance.

When the graphene metal composite material of the present invention is stretched to produce a wire or sheet, the orientation of the graphene increases during the stretching process, and the synergistic effect between the graphene and the metal between the crystal lattices of the metal is further improved, resulting in superior electrical conductivity, thermal conductivity, and physical properties compared to the original metal material.

When the graphene metal composite material of the present invention is used as an electromagnetic wave shield, the manufacturing process for electromagnetic wave shielding package parts can be simplified and it has a better electromagnetic wave shielding effect than pure copper.

Therefore, the objective of the present invention can be reliably achieved.

The above embodiment is illustrative and describes the principles and effects of the present invention, and is not intended to limit the present invention. A person skilled in the art who is familiar with this technology may make some changes or modifications to the above embodiment, provided that they do not deviate from the spirit and scope of the present invention. Therefore, all changes and modifications made by a person skilled in the art, provided that they do not deviate from the gist of the present invention, should be considered to be included in the scope of protection of the present invention.

The graphene metal composite material of the present invention is suitable for use in targets and electromagnetic wave protection packaging parts.

31: Substrate 32: Electronic component 321: Wire 33: Sealant layer 34: Electromagnetic wave prevention layer 35: Protective layer

Claims (2)

A substrate having an electrical circuit;
an electronic component disposed on the substrate so as to be electrically connected to the substrate;
an encapsulant layer encapsulating the electronic component;
An electromagnetic wave prevention layer made of a graphene metal composite material;
A protective layer made of stainless steel ;
The graphene metal composite material is composed mainly of a plurality of graphene sheets and a metal,
the plurality of graphene sheets are dispersed and arranged among the crystal lattice of the metal, and at least some of the graphene sheets are bonded together by covalent bonds;
In the entire graphene metal composite material,
The oxygen content is less than 10 ppm.
The electromagnetic wave protection package part has a graphene content of 3 wt % or less, with a total weight of the package part being 100 wt % . 2. The EMI shielding package component according to claim 1 , wherein the EMI shielding layer has a thickness of 4 [mu]m .