Active metal brazing substrate and method for manufacturing the same

Abstract

To provide an active metal brazing substrate with superior binding strength and a method for manufacturing the same.SOLUTION: An active metal layer 2 is formed from an active metal solder and an organic dispersion medium. The active metal solder includes silver, copper, and an active metal. Based on a total weight of the active metal solder being 100 wt.%, an amount of the silver ranges from 10 wt.% to 60 wt.%. A conductive metal layer 3 is disposed with the active metal layer 2 being between a ceramic substrate layer 1 and the conductive metal layer 3. A tensile strength of an active metal brazing substrate ranges from 165 N / cm to 270 N / cm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an active metal brazing substrate and a method for manufacturing the same, and more particularly to an active metal brazing substrate having good bonding strength and a method for manufacturing the same. [Background technology]

[0002] Driven by energy conservation and carbon reduction policies in various countries, the global electric vehicle market is developing vigorously. In recent years, major automakers have been launching 800-volt high-voltage vehicles one after another, which has led to a rapid growth in the demand for silicon carbide (SiC) ceramic substrate materials. . Summary of the Invention [Problem to be solved by the invention]

[0003] However, the electrical characteristics of power components that use silicon carbide (SiC) ceramic substrate materials As pressure, frequency, and operating temperature requirements increase, ceramic substrate materials are being required to provide better heat dissipation capabilities and reliability.

[0004] Conventionally, the widely used direct-bonding-copper (DBC) ceramic substrate is fabricated by the eutectic bonding method, and no bonding material exists between the copper layer and the ceramic substrate.

[0005] However, during high temperature operation, the copper layer and the ceramic substrate (Al 2 O 3 Due to the difference in thermal expansion coefficient between copper and ceramic materials (such as AlN), large thermal stress is often generated, which causes the copper layer to peel off from the surface of the ceramic substrate. Therefore, traditional copper direct bonded ceramic substrates cannot meet the packaging requirements of high temperature, high power, high heat dissipation, and high reliability.

[0006] Currently, the mainstream substrate material is gradually shifting from copper direct bonded ceramic substrates to active metal brazing (AMB) substrate materials.

[0007] Common active metal brazing substrate materials usually contain metallic silver. The silver content of active metal brazing substrate materials is usually more than 50% by weight (weight percent concentration), and even up to 70%. However, high silver content increases the cost of active metal brazing ceramic substrate materials, and there are concerns about electromigration of silver in the solder layer.

[0008] For this reason, in order to overcome the above-mentioned drawbacks, one of the important issues in this technical field is how to reduce the silver content in the solder layer by improving the composition and structural design of the solder layer.

[0009] SUMMARY OF THE DISCLOSURE In view of the above technical problems and taking into account the shortcomings of the prior art, the present invention aims to provide an active metal brazing substrate and a manufacturing method thereof. [Means for solving the problem]

[0010] In view of the above problems, the present invention has the following configuration.

[0011] 1. An active metal brazing substrate having a ceramic substrate layer, an active metal layer, and a conductive metal layer, The active metal layer is formed from an active metal solder and an organic dispersion medium, the active metal solder includes metallic silver, metallic copper, and an active metal, and the content of the metallic silver is 10 to 60% by weight when the total weight of the active metal solder is 100% by weight; The conductive metal layer is provided with the active metal layer between the ceramic substrate layer and the conductive metal layer, The tensile strength of the active metal brazing substrate is 165N / cm to 270N / cm. 1. An active metal brazing substrate comprising:

[0012] 2. When the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 30 to 50% by weight. 1. The active metal brazing substrate according to claim 1.

[0013] 3. If the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 10 to 20% by weight. 3. An active metal brazing substrate according to 1. or 2.

[0014] 4. When the total weight of the active metal solder is 100% by weight, the content of the active metal is 2 to 4% by weight. 4. The active metal brazing substrate according to any one of 1. to 3.,

[0015] 5. The active metal is selected from the group consisting of metallic titanium, metallic zirconium, metallic tantalum, metallic niobium, metallic vanadium, and metallic hafnium. 5. The active metal brazing substrate according to any one of 1. to 4.,

[0016] 6. The thickness of the active metal layer is 6 microns or more. 6. The active metal brazing substrate according to any one of 1. to 5.,

[0017] 7. Also, the thickness of the active metal layer is 18 microns to 24 microns. 6. The active metal brazing substrate according to claim 6.

[0018] 8. Also, an active metal solder paste is applied onto a ceramic substrate to form an active metal layer on the ceramic substrate; The active metal solder paste includes an active metal solder and an organic dispersion medium, the active metal solder includes metallic silver, metallic copper, and an active metal, and the content of the metallic silver is 10 to 60% by weight when the total weight of the active metal solder is 100% by weight; A conductive metal layer is provided on the active metal layer, and a brazing process is performed to obtain an active metal brazing substrate, and the tensile strength of the active metal brazing substrate is 165N / cm to 270N / cm. 2. A method for producing an active metal brazing substrate comprising the steps of:

[0019] 9. Furthermore, when the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 30 to 50% by weight, and the brazing temperature in the brazing step is 900°C to 950°C. 8. The method for producing an active metal brazing substrate according to claim 8.

[0020] 10. Furthermore, when the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 10 to 20% by weight, and the brazing temperature in the brazing step is 1000°C to 1100°C. 10. The method for producing an active metal brazing substrate according to 8. or 9. Effect of the Invention

[0021] As a beneficial effect of the present invention, the active metal brazing substrate and the manufacturing method thereof provided by the present invention can increase the bonding strength between the ceramic substrate layer and the conductive metal layer due to the technical features that "the active metal solder contains metallic silver, metallic copper, and active metal" and "the total weight of the active metal solder is 100% by weight, and the metallic silver content is 10-60% by weight." [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic side view of an active metal brazing substrate of the present invention; [Diagram 2] FIG. 2 is a schematic side view of an active metal brazing substrate according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] In order to more clearly understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the drawings. However, the attached drawings are merely illustrative for ease of understanding, and the present invention is not limited to the contents of the attached drawings.

[0024] The following are specific examples for explaining the implementation of the "active metal brazing substrate and its manufacturing method" introduced in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the contents described in this specification.

[0025] The present invention may be implemented or applied through other different specific embodiments. Various detailed descriptions in this embodiment may be modified and changed in various ways based on various viewpoints and applications without departing from the concept of the present invention, and such modified inventions are also within the technical scope of the present invention. In addition, as previously mentioned, the drawings of the present invention are merely schematic diagrams and are not necessarily drawn based on actual size.

[0026] The following embodiments will further describe the technical contents related to the present invention in detail, but the contents described therein are not intended to limit the scope of the present invention. Moreover, the term "or" used in the embodiments includes any one or more combinations of the relevant listed items according to the actual situation.

[0027] To overcome the difference in thermal expansion coefficient of traditional copper direct bonded ceramic substrates and solve the problem that the copper layer is easily peeled off from the ceramic substrate, the present invention provides an active metal brazing substrate.

[0028] In active metal brazing substrates, an active metal solder paste is used to ensure good adhesion (bonding) between the copper layer and the ceramic substrate.

[0029] Therefore, the active metal brazing substrate can be applied to some packaging structures that require high temperature, high power, and high reliability. In this specification, for ease of comparison, the bonding strength between the copper layer and the ceramic substrate is quantified as the tensile strength of the active metal brazing substrate.

[0030] 1, the active metal brazing substrate of the present invention includes a ceramic substrate layer 1, an active metal layer 2, and a conductive metal layer 3. The active metal layer 2 is provided between the ceramic substrate layer 1 and the conductive metal layer 3, and has the effect of bonding the ceramic substrate layer 1 and the conductive metal layer 3 together.

[0031] In Fig. 1, an active metal layer 2 and a conductive metal layer 3 are provided on only one side of a ceramic substrate layer 1. However, the active metal brazing substrate of the present invention is not limited to this. As shown in Fig. 2, an active metal layer 2 and a conductive metal layer 3 can also be provided on both opposing sides of a ceramic substrate layer 1.

[0032] Referring to FIG. 2, the active metal brazing substrate may have a symmetrical structure, and the active metal layer The conductive metal layers 2, 2' and 3, 3' are respectively provided on opposite sides of the ceramic substrate layer 1. In this way, the active metal brazing substrate can be used to manufacture a package structure with conductive layers on both sides.

[0033] <Ceramic substrate layer> The ceramic substrate layer 1 is a silicon nitride (SiN) ceramic substrate, a silicon carbide (SiC) ceramic substrate, an aluminum nitride (AlN) ceramic substrate, or an alumina (Al 2 O 3 ) ceramic substrate, preferably a silicon-containing ceramic substrate, more preferably a silicon nitride ceramic substrate. The thickness of the ceramic substrate layer 1 may be 100 microns to 1000 microns, but the present invention is not limited to this.

[0034] <Active metal layer> The active metal layer 2 is formed from an active metal solder and an organic dispersion medium.

[0035] Active metal solders include metallic silver (Ag), metallic copper (Cu), and active metals.

[0036] When the total weight of the active metal solder is 100% by weight, the content of metallic silver is 10 to 60% by weight. Therefore, since the active metal solder of the present invention has a low silver content, the material cost of the active metal brazing substrate can be reduced and the probability of electromigration of metallic silver can be reduced.

[0037] Specifically, the metallic silver content may be 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, or 55% by weight.

[0038] In some embodiments, the metallic silver content is 30 to 50% by weight, while in other embodiments, the metallic silver content is 10 to 20% by weight.

[0039] When the silver metallic content is changed, the copper metallic and active metal contents, as well as the brazing temperature, need to be adjusted to maintain good bonding strength between the ceramic substrate layer 1 and the conductive metal layer 3.

[0040] During the vacuum sintering process, metallic silver can diffuse into the conductive metal layer 3 and react with copper atoms in the conductive metal layer 3 at the joint surface (interface) between the active metal layer 2 and the conductive metal layer 3 to form a silver-copper alloy.

[0041] In an exemplary embodiment, when the total weight of the active metal solder is 100% by weight, the content of metallic copper is 30-80% by weight, and the content of active metal is 1-10% by weight.

[0042] Specifically, the content of metallic copper may be 35% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, or 75% by weight.

[0043] Specifically, the content of the active metal may be 2 weight %, 4 weight %, 6 weight %, or 8 weight %. When the total weight of the active metal solder is 100 weight %, the content of the active metal is preferably 2 to 4 weight %.

[0044] It should be noted that the active metal has a low melting point and will preferentially form a molten state during the vacuum sintering process. Therefore, it can help fill defects in the ceramic substrate layer 1 or the conductive metal layer 3, and even react with the ceramic substrate layer 1. Meanwhile, the addition of the active metal can also reduce the electrical impedance of the active metal layer 2. can.

[0045] Specifically, the active metal is selected from the group consisting of metallic titanium (Ti), metallic zirconium (Zr), metallic tantalum (Ta), metallic niobium (Nb), metallic vanadium (V), and metallic hafnium (Hf).

[0046] During the vacuum sintering process, some of the active metal diffuses into the interface between the active metal layer 2 and the ceramic substrate layer 1 and forms metal silicide or metal nitride with silicon or nitrogen atoms in the ceramic substrate layer 1 .

[0047] Similarly, a portion of the active metal can diffuse and react to form an alloy at the bonding surface between the active metal layer 2 and the conductive metal layer 3. In this way, a good bonding effect can be obtained between the ceramic substrate layer 1 and the conductive metal layer 3.

[0048] In a preferred embodiment, the active metal is metallic titanium. For example, during the vacuum sintering process, metallic titanium diffuses into the ceramic substrate layer 1 and then combines with silicon or nitrogen atoms to form titanium silicide (TiSi), silicon nitride (TiN), or titanium disilicate (TiSi 2 In addition, after the metallic titanium is diffused into the conductive metal layer 3, it can form a titanium-copper alloy with the copper atoms of the conductive metal layer 3, but the present invention is not limited thereto.

[0049] Furthermore, if the thickness of the active metal layer 2 is too thin, the bonding strength between the ceramic substrate layer 1 and the conductive metal layer 3 will be reduced, and if the thickness of the active metal layer 2 is too thick, the material cost of the active metal layer 2 will be too high, making mass production difficult.

[0050] For this reason, the thickness of the active metal layer 2 is 6 microns or more, and the thickness of the active metal layer 2 is 10 microns to 30 microns, and for example, the thickness of the active metal layer 2 may be 12 microns, 14 microns, 16 microns, 18 microns, 20 microns, 22 microns, 24 microns, 26 microns, or 28 microns. The thickness of the active metal layer 2 is preferably 18 microns to 24 microns.

[0051] <Conductive metal layer> The conductive metal layer 3 is provided on the ceramic substrate layer 1 via the active metal layer 2. Specifically, the conductive metal layer 3 may be a copper metal foil, an aluminum metal foil, a copper-aluminum alloy foil, or the like. In a preferred embodiment, the conductive metal layer 3 is preferably a copper metal foil.

[0052] Furthermore, the thickness of the conductive metal layer 3 is 50 μm to 1200 μm, and preferably 200 μm to 800 μm, but is not limited to this.

[0053] <Method of manufacturing active metal brazing substrate> First, in step S1, an active metal solder paste for forming the active metal layer 2 is prepared.

[0054] The active metal solder paste includes the active metal solder and an organic dispersion medium.

[0055] The active metal solder includes the aforementioned metallic silver, metallic copper, and active metal. In this embodiment, the active metal solder is a combination of metallic silver powder, metallic copper powder, and active metal powder. In other embodiments, the active metal solder may be a combination of at least one of metallic silver powder, metallic copper powder, and silver-copper alloy powder with active metal powder.

[0056] As mentioned above, the content of metallic silver in active metal solder is 10 to 60% by weight (active metal (When the total weight of the solder is 100% by weight)

[0057] The organic dispersion medium can aid in dispersing the active metal solder and aid in shaping the active metal solder paste to form the active metal layer 2. Specifically, the organic dispersion medium can include a paste-forming agent, an organic solvent, a thixotropic agent, and the like.

[0058] When the total weight of the organic dispersion medium is taken as 100% by weight, the paste content is 20 to 30% by weight, the organic solvent content is 50 to 70% by weight, and the thixotropic agent content is 1 to 5% by weight.

[0059] For example, the paste-forming agent may be selected from the group consisting of silicone oil, white oil, polyvinyl alcohol, acrylic resin, nitrocellulose, ethylcellulose, dimethyl phthalate, and carboxymethylcellulose. Preferably, the paste-forming agent is ethylcellulose.

[0060] The organic solvent is a group of glycol ethers that may be selected from the group consisting of ethylene glycol butyl ether acetate, diethylene glycol, triethanolamine, butyl cellosolve, tert-butanol, N,N-dimethylformamide, terpineol, and nonylphenol polyethylene. Preferably, the organic solvent is terpineol or ethylene glycol butyl ether acetate.

[0061] The thixotropic agent may be selected from the group consisting of polyamide wax, hydrogenated castor oil, and polyurea. Preferably, the thixotropic agent is a polyamide wax.

[0062] The active metal solder and the organic dispersion medium are mixed in a weight ratio of 70-95%:5-30% to form an active metal solder paste with a viscosity of 50 mPa·s to 300 mPa·s. The weight ratio of the active metal solder and the organic dispersion medium is preferably 75%-90%:10%-25%.

[0063] However, the present invention is not limited to the above embodiments, as long as the active solder powder and the organic components can be blended into an active solder paste having a viscosity suitable for application onto the ceramic substrate layer 1 to facilitate the formation of active solder, and as long as it conforms to the protective spirit of the present invention, it falls within the technical scope of the present invention.

[0064] In step S2, the active metal solder paste is applied onto the ceramic substrate layer 1 by screen printing, and then dried for 5 to 15 minutes at a temperature of 90°C to 110°C to volatilize most of the organic solvent in the active metal solder paste, thereby forming an active metal layer 2.

[0065] In step S3, a conductive metal layer 3 is provided on the active metal layer 2, and a brazing process is carried out to fix the conductive metal layer 3 onto the ceramic substrate layer 1.

[0066] The brazing process is composed of a first stage heat treatment process and a second stage heat treatment process that can be performed in a vacuum environment. The temperature condition of the first stage heat treatment process is 500°C or less, and the temperature condition of the second stage heat treatment process is 900°C to 1100°C (brazing temperature range), and the temperature of the second stage heat treatment process is higher than that of the first stage heat treatment process.

[0067] Specifically, the temperature conditions for the first stage heat treatment are 300° C. to 500° C., and the treatment time is 30 to 60 minutes, while the temperature conditions for the second stage heat treatment are 900° C. to 1100° C., and the treatment time is 60 to 240 minutes.

[0068] The temperature increase rate of the heat treatment program can be, for example, 5° C. / min to 30° C. / min. The temperature decrease rate after completion of the vacuum high-temperature sintering can be, for example, 2° C. / min to 30° C. / min.

[0069] It should be noted that the brazing temperature in the brazing process is adjusted according to the different silver content in the active metal layer 2 so that the active metal brazing substrate has good tensile strength.

[0070] Specifically, when the content of metallic silver in the active metal layer 2 is 30 to 50% by weight, the brazing temperature in the brazing step can be 900°C to 950°C. When the content of metallic silver in the active metal layer 2 is 10 to 20% by weight, the brazing temperature in the brazing step can be 1000°C to 1100°C.

[0071] During the brazing process, a part of the organic dispersion medium evaporates, and the active metal wets the surface of the ceramic substrate layer 1. Then, the active metal reacts with the ceramic substrate layer 1, thereby enhancing the bonding strength between the active metal layer 2 and the ceramic substrate layer 1.

[0072] In addition, a micron-scale eutectic reaction occurs at the interface between the active metal and the metal component of the conductive metal layer 3, forming a strong eutectic structure, and the active metal layer 2 and the conductive metal layer 3 are firmly bonded together.

[0073] <Test Examples 1 to 10> In order to compare the effects of the silver content in the active metal layer 2, the brazing temperature, and the thickness of the active metal layer 2, which affect the tensile strength of the active metal brazed substrate, metal brazed substrates of test examples 1 to 10 were prepared based on the above steps S1 to S3.

[0074] In the metal brazing substrates of Test Examples 1 to 10, the ceramic substrate layer 1 is a silicon nitride ceramic substrate, the active metal layer 2 contains metallic silver, metallic copper, and metallic titanium, and the conductive metal layer 3 is a copper metal layer. In these test examples, the metallic titanium content is controlled to 1 to 5 wt%, but as an example, when the metallic titanium content is 4 wt%, the remainder may be copper.

[0075] To prepare the active metal solder paste, ethyl cellulose is used as a paste-forming agent, ethylene glycol butyl ether acetate as an organic solvent, and polyamide wax as a thixotropic agent. When the total weight of the organic dispersion medium is taken as 100% by weight, the organic dispersion medium contains 20-30% by weight of the paste-forming agent, 50-70% by weight of the organic solvent, and 1-5% by weight of the thixotropic agent. In this embodiment, the composition of the organic dispersion medium is 30% by weight of paste, 67% by weight of organic solvent, and 3% by weight of the thixotropic agent.

[0076] The specific content of metallic silver in the active metal solder paste (active metal layer 2), the brazing temperature in the brazing process, and the thickness of the active metal layer 2 formed after the brazing process are shown in Table 1. In addition, the tensile strength of the active metal brazed substrate was measured at a temperature of 25°C in accordance with the JIS-C-6481 standard, and the results are shown in Table 1.

[0077] [Table 1]

[0078] The results in Table 1 show that when the silver content in the active metal layer is 10-60% by weight, the tensile strength of the active metal brazing substrate can be 165N / cm-270N / cm. Test Examples 1-4 show that when the silver content in the active metal layer is 20-50% by weight, the tensile strength of the active metal brazing substrate can be 180N / cm-270N / cm.

[0079] Even if the thickness of the active metal layer is reduced to 18 microns, the tensile strength of the active metal brazing substrate can still have the same effect. According to the test examples 5 to 7, even if the silver content in the active metal layer is 20 to 50 wt%, the active metal brazing substrate can have a tensile strength of 180 N / cm to 270 N / cm.

[0080] Experimental results show that the tensile strength of the active metal brazing substrate is greatly improved with increasing brazing temperature. According to Test Examples 8-9, when the brazing temperature is increased to 1015°C, even if the silver content in the active metal layer is only 10-20% by weight, the active metal brazing substrate can still have a tensile strength of 140N / cm-250N / cm.

[0081] From the above results, by adjusting the silver content in the active metal and the brazing temperature, the active metal brazed substrate of the present invention has good tensile strength and can be applied to packaging structures that meet the requirements of high temperature, high power, and high reliability.

[0082] [Effects of this embodiment] One of the advantageous effects of the present invention is that the active metal brazing substrate and the manufacturing method thereof provided by the present invention are "active metal solder containing metallic silver, metallic copper, and active metal" and "when the total weight of the active metal solder is 100% by weight, the content of metallic silver is 10 to 60% by weight." This technical feature improves the bonding strength between the ceramic substrate layer and the conductive metal layer.

[0083] The above description is merely a preferred embodiment of the present invention, and does not limit the technical scope of the present invention. Therefore, any technical modifications made with reference to the specification and drawings of the present invention are equivalent to the present invention and are included in the technical scope of the present invention. [Explanation of symbols]

[0084] 1 Ceramic Substrate Layer 2, 2' active metal layer 3,3' Conductive metal layer

Claims

1. An active metal brazing substrate comprising a ceramic substrate layer, an active metal layer, and a conductive metal layer, the active metal layer is formed from an active metal solder and an organic dispersion medium, the active metal solder includes metallic silver, metallic copper, and an active metal, and the content of the metallic silver is 10 to 60 wt % when the total weight of the active metal solder is 100 wt %; The conductive metal layer is provided with the active metal layer between the ceramic substrate layer and the conductive metal layer, The tensile strength of the active metal brazing substrate is 165N / cm to 270N / cm.

1. An active metal brazing substrate comprising:

2. When the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 30 to 50% by weight.

2. The active metal brazing substrate according to claim 1 .

3. When the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 10 to 20% by weight.

2. The active metal brazing substrate according to claim 1 .

4. When the total weight of the active metal solder is 100% by weight, the content of the active metal is 2 to 4% by weight.

2. The active metal brazing substrate according to claim 1 .

5. The active metal is selected from the group consisting of metallic titanium, metallic zirconium, metallic tantalum, metallic niobium, metallic vanadium, and metallic hafnium.

2. The active metal brazing substrate according to claim 1 .

6. The active metal layer has a thickness of 6 microns or more.

2. The active metal brazing substrate according to claim 1 .

7. The active metal layer has a thickness of 18 to 24 microns.

7. The active metal brazing substrate according to claim 6.

8. Applying an active metal solder paste onto a ceramic substrate to form an active metal layer on the ceramic substrate; The active metal solder paste includes an active metal solder and an organic dispersion medium, the active metal solder includes metallic silver, metallic copper, and an active metal, and the content of the metallic silver is 10 to 60 wt % when the total weight of the active metal solder is 100 wt %; A conductive metal layer is provided on the active metal layer, and a brazing process is performed to obtain an active metal brazing substrate, and the tensile strength of the active metal brazing substrate is 165N / cm to 270N / cm.

2. A method for producing an active metal brazing substrate comprising the steps of:

9. When the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 30 to 50% by weight, and the brazing temperature in the brazing step is 900° C. to 950° C. The method for producing an active metal brazing substrate according to claim 8 .

10. When the total weight of the active metal solder is 100% by weight, the content of the metallic silver is 10 to 20% by weight, and the brazing temperature in the brazing step is 1000° C. to 1100° C. The method for producing an active metal brazing substrate according to claim 8 .

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