Metal and electronic device

Abstract

The metal according to the present invention contains Ga and Bi, and contains a liquid metal or a liquid metal and a solid metal at 35 DEG C. The metal according to the present invention may contain 0.01% by mass or more and 30% by mass or less of Bi. The metal according to the present invention may further contain one or more of In, Sn, Zn, and Ag.

Description

Technical Field

[0001] The present invention relates to a metal and an electronic device using the metal. Background Art

[0002] In the past, attempts have been made to provide liquid metals. For example, Japanese Patent Application No. 2019-516208 proposes providing a conductive shear viscosity-reducing gel composition comprising a eutectic gallium alloy and gallium oxide sheets distributed as a microstructure in the gallium alloy. The mixture of the eutectic gallium alloy and gallium oxide has a eutectic gallium alloy of approximately 59.9% to approximately 99.9% by weight (wt%) and gallium oxide of approximately 0.1% to approximately 2.0% by weight. Summary of the invention

[0003] Problems to be solved by the invention

[0004] In the metal containing liquid metal containing Ga as disclosed in Japanese Patent Publication No. 2019-516208, due to the easy oxidation of Ga, the oxide grows while generating hydrogen, resulting in shape change and reduced heat dissipation. In particular, under high temperature and high humidity, the tendency of Ga to selectively oxidize becomes stronger.

[0005] The present invention provides a metal that contains Ga and liquid metal but is not easily oxidized, and an electronic device using the metal.

[0006] Means for solving problems

[0007] [Concept 1]

[0008] The metal according to the present invention may contain Ga and Bi and contain liquid metal at 35°C, or contain liquid metal and solid metal.

[0009] [Concept 2]

[0010] The metal according to Concept 1 may contain Bi at 0.01 mass % or more and 30 mass % or less.

[0011] [Concept 3]

[0012] The metal according to Concept 1 or 2 may further contain any one or more of In, Sn, Zn and Ag.

[0013] [Concept 4]

[0014] The metal according to any one of concepts 1 to 3 may further contain one or more of Ag, Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg, Mn, Co, Ge, Cd, Pb, P, S and Si.

[0015] [Concept 5]

[0016] The metal according to any one of Concepts 1 to 4 may contain Ga at 30 mass % or more and 99.99 mass % or less, and

[0017] Bi is contained in an amount of 0.01 mass % to 30 mass %.

[0018] [Concept 6]

[0019] In the metal according to any one of Concepts 1 to 5,

[0020] The remainder other than Ga and Bi may be composed of any one or more of In, Sn, Zn, and Ag.

[0021] [Concept 7]

[0022] In the metal according to any one of Concepts 1 to 5,

[0023] The remainder other than Ga and Bi can be composed as follows:

[0024] Any one or more of In, Sn, Zn and Ag, and

[0025] Any one or more of Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg, Mn, Co, Ge, Cd, Pb, P, S and Si.

[0026] [Concept 8]

[0027] The metal according to any one of Concepts 1 to 7 can be used as a heat dissipation material.

[0028] [Concept 9]

[0029] The electronic device according to the present invention can use the metal according to any one of Concepts 1 to 7 as a heat dissipation material.

[0030] According to the present invention, it is possible to provide a metal or the like which contains Ga or liquid metal but is not easily oxidized. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1A This is a photograph of 24.5 In-GaBal of grade F containing no Bi after being treated in an environment of 85°C and 85% RH for 48 hours.

[0032] Figure 1B This is a photograph of 24.5 In-GaBal of Grade A containing 1.5% Bi after being treated in an environment of 85°C and 85% RH for 48 hours.

[0033] Figure 2This is a through-hole substrate as a test substrate used in Examples.

[0034] Figure 3A This is a photograph of a test substrate filled with the metal of the present embodiment as viewed from the front.

[0035] Figure 3B This is an enlarged photograph of a test substrate filled with the metal of the present embodiment as viewed from the front.

[0036] Figure 3C This is a photograph of a test substrate filled with the metal of the present embodiment as viewed from the back side.

[0037] Figure 4 This is an example of an image obtained by measurement. DETAILED DESCRIPTION

[0038] The metal of the present embodiment contains Ga and Bi, and may be a liquid metal at 35°C, or may be a form containing a liquid metal and a solid metal at 35°C. Each or one of the liquid metal and the solid metal may be an alloy. The composition of the alloy in the liquid metal may be different from the composition of the alloy in the solid metal. However, it is not limited to such a form, and the composition of the alloy in the liquid metal may be the same composition as the composition of the alloy in the solid metal. The metal of the present embodiment may be a Ga-based metal. The metal of the present embodiment preferably contains a liquid metal at 30°C, or contains a liquid metal and a solid metal. It should be noted that the melting point of Ga is about 30°C, so by using Ga as a matrix, a metal containing a liquid metal or a mixture of a liquid metal and a solid metal can be provided. Ga may be contained at 30% by mass or more and less than 100% by mass. Ga is a metal with a high heat dissipation effect, and in addition, it can be in a liquid state by containing Ga, so its lower limit is preferably 30% by mass, more preferably 40% by mass, and further more preferably 50% by mass.

[0039] The metal may contain Bi at 0.01% by mass or more and 30% by mass or less relative to the whole (in the case of being composed of liquid metal, the whole of the liquid metal; in the case of being a mixture of liquid metal and solid metal, the whole of the mixture). The lower limit of Bi is preferably 0.03% by mass, more preferably 0.05% by mass, and further more preferably 0.1% by mass. It should be noted that if the content of Bi is too much, the heat dissipation becomes poor, and therefore, the upper limit is preferably set to 30% by mass, more preferably 20% by mass, further preferably 15% by mass, and further more preferably 10% by mass.

[0040] The metal of this embodiment is generally used as a heat dissipation material such as heat dissipation grease. In this embodiment, an electronic device using such a metal is also provided. As an example, in the electronic device of this embodiment, the electronic component is placed on the circuit substrate via the heat dissipation grease composed of liquid metal or liquid metal and solid metal. The metal of this embodiment can be printed on the circuit substrate such as a printed wiring board using a scraper, can be printed using an inkjet printer, and can be applied using a dispensing device.

[0041] The metal of this embodiment may contain only Ga and Bi, or may contain any one or more of In, Sn, Zn and Ag in addition to Ga and Bi. In this case, it may be composed of Ga, Bi and inevitable impurities, or may be composed of inevitable impurities and Ga in addition to Bi and any one or more metals selected from In, Sn, Zn and Ag. The inevitable impurities in this application refer to impurities that are not intentionally added. The metal of this embodiment may be a eutectic metal alloy, or may not be a eutectic metal alloy.

[0042] The inventors of the present application have conducted intensive research on the problem of Ga oxides in metals containing liquid metals, and have found that the inclusion of Bi can suppress the oxidation of Ga. Although it is only a guess, the mechanism by which the use of Bi can suppress the oxidation of Ga is considered to be as follows.

[0043] Bi is an element classified as an acidic oxide, and has the property of reacting with water to generate an acid. Therefore, by containing Bi, an acid is generated, and the generated acid reacts with Ga to generate a hydroxide on the surface of the alloy. It is believed that by generating such a hydroxide on the surface of the alloy, the reaction of Ga with water can be suppressed, and the generation of Bi oxide can be suppressed.

[0044] The content of metals other than Ga and Bi may be 70 mass % or less, 60 mass % or less, 50 mass % or less, 40 mass % or less, 30 mass % or less, or 20 mass % or less.

[0045] As an example, it can be composed of a quinary alloy such as Ga-In-Sn-Zn-Bi, a quaternary alloy such as Ga-In-Sn-Bi, Ga-Sn-Zn-Bi, a ternary alloy such as Ga-In-Bi, or a binary alloy of Ga-Bi.

[0046] As an example, a metal having the following composition can be cited: It should be noted that, in the case of being composed of liquid metal, the mass % of the entire liquid metal is shown below, and in the case of being composed of a mixture of liquid metal and solid metal, the mass % of the entire mixture is shown below.

[0047] A metal composed of 2 to 35 mass % In, 0.01 to 30 mass % Bi, and the remainder Ga, and containing liquid metal at 35° C., or containing liquid metal and solid metal.

[0048] A metal composed of 2 to 30 mass % Sn, 0.01 to 30 mass % Bi, and the remainder Ga, and containing a liquid metal at 35° C., or containing a liquid metal and a solid metal.

[0049] A metal composed of 2 to 30 mass % Sn, 0.3 to 10 mass % Zn, 0.01 to 30 mass % Bi, and the remainder Ga, and containing liquid metal at 35° C., or containing liquid metal and solid metal.

[0050] A metal containing liquid metal at 35°C, or containing liquid metal and solid metal, which is composed of 2 to 40 mass% In, 2 to 30 mass% Sn, 0.01 to 30 mass% Bi, and the remainder Ga. It should be noted that the following metal can be obtained: in this composition, the upper limit of In is 20 mass%, and the metal containing liquid metal at 35°C, or containing liquid metal and solid metal, which is composed of 2 to 20 mass% In, 2 to 30 mass% Sn, 0.01 to 30 mass% Bi, and the remainder Ga.

[0051] A metal composed of 1 to 10 mass % of Zn, 0.01 to 30 mass % of Bi, and the remainder of Ga, and containing a liquid metal at 35° C., or containing a liquid metal and a solid metal.

[0052] A metal composed of 1 to 10 mass % of Ag, 0.01 to 30 mass % of Bi, and the remainder of Ga, and containing a liquid metal at 35° C., or containing a liquid metal and a solid metal.

[0053] A metal composed of 1 to 35 mass % In, 5 to 20 mass % Sn, 0.1 to 5 mass % Zn, 0.01 to 30 mass % Bi, and the remainder Ga, and containing liquid metal at 35° C., or containing liquid metal and solid metal.

[0054] It should be noted that the inventors have confirmed that the amount of Bi contained in the liquid metal is limited. Therefore, if only the viewpoint that the liquid contains Bi and has an excellent heat dissipation effect is considered, (especially in the method shown in the above example, containing In and Sn or containing In, Sn and Zn) the upper limit of the Bi content is preferably 1.5% by mass, more preferably 1.0% by mass, and further preferably 0.8% by mass. In addition, if it is more reliable to only attach importance to the presence of Bi in the form of liquid, a method with an upper limit of 0.4% by mass can also be adopted.

[0055] In addition, in these methods, the remainder may also contain unavoidable impurities.

[0056] However, it is not limited to such a method. For example, on the basis of containing Ga and Bi, and any one or more of In, Sn and Zn, it can also contain any one or more of Ag, Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg, Mn, Co, Ge, Cd, Pb, P, S and Si. In addition, it is also possible not to contain In, Sn and Zn, and on the basis of containing Ga and Bi, it can also contain any one or more of Ag, Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg, Mn, Co, Ge, Cd, Pb, P, S and Si. Moreover, the remainder can be Ga and unavoidable impurities. It should be noted that in this application, even if it is recorded in a closed item, unavoidable impurities are included. Unavoidable impurities refer to impurities that are not intentionally contained.

[0057] As an example, the following metals can be cited. Here, too, when composed of liquid metal, the mass % of the entire liquid metal is shown below, and when composed of a mixture of liquid metal and solid metal, the mass % of the entire mixture is shown below.

[0058] A metal containing liquid metal at 35°C, or containing liquid metal and solid metal, which is composed of 5 to 20 mass% Sn, 0.1 to 5 mass% Zn, 0.01 to 30 mass% Bi, 0.01 to 1 mass% of one or more of Ag, Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg and Mn, and the remainder Ga.

[0059] A metal containing liquid metal at 35°C, or containing liquid metal and solid metal, which is composed of 2 to 35 mass% In, 0.01 to 30 mass% Bi, 0.01 to 1 mass% of one or more of Ag, Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg and Mn, and the remainder Ga.

[0060] In these methods as well, the remainder may contain inevitable impurities.

[0061] The heat dissipation material containing the metal of the present embodiment may further include amine, resin, solvent, etc. In this case, 10 to 90% by mass of the metal according to the present embodiment (liquid metal or a mixture of liquid metal and solid metal), 10 to 90% by mass of amine, 10 to 90% by mass of resin and 10 to 90% by mass of solvent may be included, and the whole may be 100% by mass. In addition, it may be a mode in which the remainder is composed of an active agent, or an active agent and a solvent, relative to 10 to 90% by mass of the metal.

[0062] Examples of the amine include linear, branched and / or cyclic saturated or unsaturated aliphatic amines, aromatic amines, and imidazoles. Examples of the aliphatic amine include methylamine, ethylamine, dimethylamine, 1-aminopropane, isopropylamine, trimethylamine, n-ethylmethylamine, allylamine, n-butylamine, diethylamine, sec-butylamine, tert-butylamine, N,N-dimethylethylamine, isobutylamine, pyrrolidine, 3-pyrroline, n-pentylamine, dimethylaminopropane, 1-aminohexane, triethylamine, diisopropylamine, dipropylamine, hexamethyleneimine, 1-methylpiperidine, 2-methylpiperidine, 4-methylpiperidine, cyclohexylamine, diallylamine, n-octylamine, aminomethyl, cyclohexane, 2-ethylhexylamine, dibutylamine, diisobutylamine, 1,1,3,3-tetramethylbutylamine, 1-cyclohexylethylamine, and N,N-dimethylcyclohexylamine. Examples of the aromatic amines include aniline, diethylaniline, pyridine, diphenylguanidine, and xylylguanidine. Examples of the imidazoles include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 1-benzyl-2-phenylimidazole.

[0063] Examples of the resin include epoxy resins, rosin resins, (meth) acrylic resins, urethane resins, polyester resins, phenoxy resins, vinyl ether resins, terpene resins, modified terpene resins (e.g., aromatic modified terpene resins, hydrogenated terpene resins, hydrogenated aromatic modified terpene resins, etc.), terpene phenolic resins, modified terpene phenolic resins (e.g., hydrogenated terpene phenolic resins, etc.), styrene resins, modified styrene resins (e.g., styrene acrylic resins, styrene maleic resins, etc.), xylene resins, modified xylene resins (e.g., phenol-modified xylene resins, alkylphenol-modified xylene resins, phenol-modified resol-type xylene resins, polyol-modified xylene resins, polyoxyethylene-added xylene resins, etc.), and the like.

[0064] Examples of the solvent include alcohol solvents, glycol ether solvents, terpineols, hydrocarbons, esters, and water.

[0065] Example

[0066] Hereinafter, the present embodiment will be described in detail with reference to Examples and Comparative Examples. It should be noted that the present embodiment is not limited to these Examples.

[0067] [Test method]

[0068] 1. Method of making metal for test

[0069] In a beaker, a predetermined amount of additional elements (elements other than Bi shown in each table) were weighed and added to Ga that had been preheated to 40°C to make a liquid (the amount added became the amount shown in each table described later), and heated on a 250°C hot plate for 1 hour to produce a mother alloy.

[0070] The mother alloy was weighed in a beaker, a predetermined amount of Bi was added (the amount added was the amount shown in the following tables), and the mixture was heated on a hot plate at 250° C. for 1 hour and cooled to room temperature to prepare a test sample.

[0071] 2. Test piece preparation method

[0072] exist Figure 2 The through-hole substrate shown was filled with metal to prepare a test piece.

[0073] The test substrate made of the through-hole substrate was as follows.

[0074] ・Material: FR4 (copper foil, no resist)

[0075] ・Plate thickness 0.50mm

[0076] ・Aperture Φ0.525mm

[0077] ・Number of holes: 14×14=196

[0078] ・Hole distance 0.90mm

[0079] (1) A test sample is filled in a through hole of a test substrate.

[0080] (2) Use IPA to wipe off the excess metal on the front and back.

[0081] (3) The back surface was sealed with Kapton tape to prepare a test piece.

[0082] (4) The prepared test piece was treated in an environment of 85° C. and 85% RH (relative humidity) for 48 hours, and the growth state of the oxide was measured. Figure 3A and Figure 3B This is a photo of the test substrate after metal filling, viewed from the front. Figure 3C This is a photograph of the test substrate after metal filling as viewed from the back side.

[0083] 3. Determination method

[0084] The maximum height of the oxide from the substrate surface in each hole was measured using a VK-X1000 laser microscope manufactured by KEYENCE.

[0085] The judgment criteria are as follows.

[0086] Maximum height of oxide

[0087] Grade A: less than 250μm

[0088] Grade B 250μm or more and less than 500μm

[0089] Grade C 500μm or more and less than 750μm

[0090] Grade D 750μm or more and less than 1000μm

[0091] Grade E 1000μm or more and less than 1500μm

[0092] Grade F 1500μm or more and less than 1750μm

[0093] Grade G 2000μm and above

[0094] Figure 1A This is a photo of 24.5In-GaBal of grade F that does not contain Bi after being treated in an environment of 85°C and 85%RH for 48 hours. Figure 1B This is a photograph of 24.5 In-GaBal of grade A containing 1.5 mass % of Bi after being treated in an environment of 85° C. and 85% RH for 48 hours. Figure 4 An image obtained by measurement is shown as an example.

[0095] The results of the examples and comparative examples are shown in the following tables. In the following tables and this specification, the remainder is indicated as "Bal". In addition, in each table, when the alloy is composed of liquid metal, the mass % of the entire liquid metal is shown, and when it is composed of a mixture of liquid metal and solid metal, the mass % of the entire mixture is shown.

[0096] From the experimental results shown in the following table, it can be understood that the growth of oxides can be effectively suppressed by including Bi in each composition. In addition, the growth of oxides can be effectively suppressed by increasing the content of Bi.

[0097] More specifically, Tables 1 and 2 show the results of alloys containing In in addition to Ga and Bi. The inclusion of Bi can effectively suppress the growth of oxides. In addition, this effect can be further enhanced by increasing the content of Bi.

[0098]

[0099]

[0100] Table 3 shows the results of the alloy containing Sn in addition to Ga and Bi. The inclusion of Bi can effectively suppress the growth of oxides. In addition, by increasing the content of Bi, this effect can be further enhanced.

[0101]

[0102] Tables 4 and 5 show the results of alloys containing Sn and Zn in addition to Ga and Bi. The inclusion of Bi can effectively suppress the growth of oxides. In addition, by increasing the content of Bi, this effect can be further enhanced.

[0103]

[0104]

[0105] Tables 6 and 7 show the results of alloys containing Ga and Bi and Sn and In. The inclusion of Bi can effectively suppress the growth of oxides. In addition, this effect can be further enhanced by increasing the content of Bi.

[0106]

[0107]

[0108] Table 8 shows the results of the alloy containing Zn in addition to Ga and Bi. The inclusion of Bi can effectively suppress the growth of oxides. In addition, by increasing the content of Bi, this effect can be further enhanced.

[0109]

[0110] Table 9 shows the results of the alloy containing Ag in addition to Ga and Bi. The inclusion of Bi can effectively suppress the growth of oxides. In addition, by increasing the content of Bi, this effect can be further enhanced.

[0111]

[0112] Table 10 shows the results of alloys containing In, Sn, and Zn in addition to Ga and Bi. The inclusion of Bi can effectively suppress the growth of oxides. In addition, by increasing the content of Bi, this effect can be further enhanced.

[0113]

[0114] Tables 11 to 13 show the results of alloys containing Sn, Zn, and other additive elements in addition to Ga and Bi. By containing Bi, the growth of oxides can be effectively suppressed. In addition, by increasing the content of Bi, this effect can be further enhanced.

[0115]

[0116]

[0117]

[0118] Tables 14 to 17 show the results of alloys containing In and other additive elements in addition to Ga and Bi. By containing Bi, the growth of oxides can be effectively suppressed. In addition, by increasing the content of Bi, this effect can be further enhanced.

[0119]

[0120]

[0121]

[0122]

[0123] The description of the above-mentioned embodiments, the description of the examples, and the disclosure of the drawings are merely examples for explaining the invention described in the claims, and the invention described in the claims is not limited to the description of the above-mentioned embodiments or the disclosure of the drawings.

Claims

1. A metal containing Ga and Bi and containing liquid metal at 35°C, or containing liquid metal and solid metal. 2 . The metal according to claim 1 , comprising Bi in an amount of 0.01 mass % to 30 mass %. 3 . The metal according to claim 1 , further comprising any one or more of In, Sn, Zn and Ag.

4. The metal according to claim 1 or 2, further comprising any one or more of Ag, Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg, Mn, Co, Ge, Cd, Pb, P, S and Si.

5. The metal according to claim 1 or 2, containing Ga in an amount of 30 mass % or more and 99.99 mass % or less, and Bi is contained in an amount of 0.01 mass % to 30 mass %.

6. The metal according to claim 1 or 2, wherein The remainder other than Ga and Bi is composed of one or more of In, Sn, Zn and Ag.

7. The metal according to claim 1 or 2, wherein The remainder other than Ga and Bi is composed of: Any one or more of In, Sn, Zn and Ag, and Any one or more of Sb, Cu, Fe, Al, As, Ni, Au, Ti, Cr, La, Mg, Mn, Co, Ge, Cd, Pb, P, S and Si.

8. The metal according to claim 1 or 2, used as a heat dissipation material.

9. An electronic device using the metal according to claim 1 or 2 as a heat dissipation material.

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