Preparation method of copper-clad ceramic substrate

Abstract

The invention provides a preparation method of a copper-clad ceramic substrate, and the preparation method comprises the following steps: (1) coating metal modified layers on the surfaces of two sides of the ceramic substrate, and then carrying out sintering treatment; the temperature of the sintering treatment is 800 to 900 DEG C; and (2) plating a copper layer on the surface of the metal modified layer subjected to sintering treatment in the step (1), and then performing brazing treatment to obtain the copper-clad ceramic substrate. The surfaces of the two sides of the ceramic substrate are coated with the metal modified layers, then sintering treatment is carried out, and finally the copper layer is jointed through brazing treatment, so that the combination of the copper layer and the ceramic substrate is easier to realize, and the combination strength of the copper layer and the ceramic substrate is improved; and meanwhile, the metal modification layer is arranged, so that stress concentration between the metal thin copper layer and the ceramic substrate during cold and hot circulation is effectively relieved, and the reliability of the copper-clad ceramic substrate is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of copper-clad substrates and relates to a method for preparing a copper-clad ceramic substrate. Background Art

[0002] With the continuous development of technology, high-power LEDs are being used more and more widely. At the same time, as the power of LEDs increases, the heat dissipation problem becomes more and more prominent. Generally speaking, as the temperature inside the LED chip (junction temperature) increases, the light efficiency and service life of the LED device will decrease. When the junction temperature exceeds 125°C, the LED may even fail.

[0003] Due to the limitation of technical conditions, the current luminous conversion efficiency of LED is only about 20%-30%, and most of the remaining energy is converted into heat energy and dissipated. For high-power LED, if the heat is accumulated inside the chip and not discharged in time, the luminous efficiency of LED will be reduced, and more seriously, the life of LED will be affected. Therefore, providing a heat dissipation substrate with low thermal resistance, high thermal conductivity and high reliability is the key to solve the current LED packaging system.

[0004] Direct copper plating (DPC) is the mainstream technology for high-power LED heat dissipation substrates. The process is to pre-sputter a seed layer on the surface of the ceramic substrate, then realize the circuit pattern through exposure, development, and etching processes, and finally increase the thickness of the copper layer through electroplating or chemical plating to complete the final DPC substrate preparation. However, the DPC process uses the mechanical bite between the metal copper layer, seed layer and ceramic layer to achieve mutual bonding, which is a physical bond and has the problem of low bonding strength; in addition, the metal layer and the ceramic layer are prone to stress concentration during hot and cold cycles, resulting in peeling failure between the metal and the ceramic.

[0005] In summary, providing a method for preparing a copper-clad ceramic substrate with high reliability and high bonding strength is an issue that needs to be urgently addressed by those skilled in the art. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing a copper-clad ceramic substrate, which improves the bonding strength between the copper layer and the ceramic substrate, while effectively alleviating stress concentration between the metal thin copper layer and the ceramic substrate during hot and cold cycles, thereby improving the reliability of the copper-clad ceramic substrate.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing a copper-clad ceramic substrate, characterized in that the preparation method comprises the following steps:

[0009] (1) coating a metal modified layer on both sides of a ceramic substrate and then performing a sintering process;

[0010] The sintering temperature is 800-900°C, for example, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C or 890°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0011] (2) A copper layer is plated on the surface of the metal modified layer after the sintering treatment in step (1), and then brazing is performed to obtain the copper-clad ceramic substrate.

[0012] The present invention provides a preparation method of a copper-clad ceramic substrate. The method comprises the following steps: coating a metal modified layer on both sides of the ceramic substrate, then performing a sintering treatment, and finally joining the copper layer by brazing treatment, so that the copper layer and the ceramic substrate are more easily bonded, thereby improving the bonding strength between the copper layer and the ceramic substrate. At the same time, by providing the metal modified layer, the stress concentration between the metal thin copper layer and the ceramic substrate during the hot and cold cycle is effectively alleviated, thereby improving the reliability of the copper-clad ceramic substrate.

[0013] It is worth noting that controlling the sintering temperature range after coating the metal modified layer not only helps to form an effective active metal modified layer, but also helps to increase the bonding strength between the metal modified layer and the ceramic substrate.

[0014] As a preferred technical solution of the present invention, the material of the ceramic substrate in step (1) includes any one of aluminum oxide, aluminum nitride or silicon nitride.

[0015] Preferably, the thickness of the ceramic substrate in step (1) is 0.25-1 mm, for example, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm or 0.9 mm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] As a preferred technical solution of the present invention, the coating method in step (1) includes any one of screen printing, spraying or roller coating, or a combination of at least two of them.

[0017] As a preferred technical solution of the present invention, the thickness of the metal modification layer in step (1) is 5-15 μm, for example, it can be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or 14 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] As a preferred technical solution of the present invention, the metal modification layer in step (1) includes the following elements: Ag, Cu and active metal elements.

[0019] In the present invention, the mass sum of the elements in the metal modification layer is not 100%, and the raw materials in the metal modification layer also include an organic carrier (organic solvent), and the mass sum of the organic carrier and the elements in the metal modification layer is 100%. By adding the organic carrier, it is easy to dissolve various solid components in the solder, and the wettability and coating performance of the solder can also be improved.

[0020] Preferably, the mass percentage of the Ag element in the metal modification layer in step (1) is 40wt%-90wt%, for example, it can be 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt% or 85wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, the mass percentage of the Cu element in the metal modification layer in step (1) is 10wt%-50wt%, for example, it can be 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 48wt%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the total mass percentage of Ag and Cu contained in the metal modification layer of step (1) is ≥82wt%, for example, it can be 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt% or 95wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the active metal element includes any one of Ti, Zr, Hf, Cr, V, Si or Al, or a combination of at least two of them, wherein the combination is typically but not limited to: a combination of Ti and Zr, a combination of Hf and Cr, a combination of Ti and Cr, or a combination of Ti and Al, etc.

[0024] As a preferred technical solution of the present invention, the sintering treatment in step (1) is carried out under vacuum or inert gas protection.

[0025] In the present invention, the inert gas includes nitrogen and / or argon.

[0026] Preferably, the sintering time in step (1) is 10-60 min, for example, 15 min, 20 min, 30 min, 35 min, 40 min, 45 min, 50 min or 55 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] As a preferred technical solution of the present invention, the copper plating method in step (2) includes electroplating or screen printing.

[0028] As a preferred technical solution of the present invention, the thickness of the copper layer in step (2) is 5-75 μm, for example, it can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 60 μm or 70 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] As a preferred technical solution of the present invention, the brazing process in step (2) is carried out under vacuum or inert gas protection.

[0030] Preferably, the temperature of the brazing treatment in step (2) is 800-1000°C, for example, it can be 820°C, 840°C, 850°C, 860°C, 880°C, 900°C, 920°C, 940°C, 950°C, 960°C or 980°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the brazing treatment time in step (2) is 10-60 min, for example, it can be 15 min, 20 min, 30 min, 35 min, 40 min, 45 min, 50 min or 55 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0033] (1) coating a metal modification layer with a thickness of 5-15 μm on both sides of a ceramic substrate with a thickness of 0.25-1 mm, and then sintering the ceramic substrate at a temperature of 800-900° C. for 10-60 min under vacuum or inert gas protection;

[0034] The metal modification layer includes the following elements: Ag, Cu and active metal elements; the active metal elements include any one or a combination of at least two of Ti, Zr, Hf, Cr, V, Si or Al;

[0035] The mass percentage of Ag in the metal modification layer is 40wt%-90wt%; the mass percentage of Cu in the metal modification layer is 10wt%-50wt%; the total mass of Ag and Cu in the metal modification layer is ≥82wt%;

[0036] (2) A copper layer with a thickness of 5-75 μm is plated on the surface of the metal modified layer after sintering treatment in step (1), and then a brazing treatment is performed for 10-60 minutes at a temperature of 800-1000° C. under vacuum or inert gas protection to obtain the copper-clad ceramic substrate.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The preparation method of the copper-clad ceramic substrate provided by the present invention comprises coating a metal modification layer on both sides of the ceramic substrate, then performing a sintering treatment, and finally joining the copper layer by brazing treatment. By controlling the range of relevant parameters such as component content and temperature in the above process, the copper layer and the ceramic substrate are more easily bonded, thereby improving the bonding strength between the copper layer and the ceramic substrate. At the same time, the stress concentration between the metal thin copper layer and the ceramic substrate during the hot and cold cycle is effectively alleviated, thereby improving the reliability of the copper-clad ceramic substrate.

[0039] (2) The method for preparing the copper-clad ceramic substrate provided by the present invention has simple process operation, does not require complicated process conditions, has low preparation cost, and has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the structure of the copper-clad ceramic substrate prepared in Example 1;

[0041] Figure 2 This is an electron microscope characterization image of the copper-clad ceramic substrate prepared in Example 1;

[0042] Among them, 1-ceramic substrate, 2-metal modified layer, 3-copper layer. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] In the following embodiments and comparative examples, the organic carrier used in the metal modification layer is not specifically limited, and those skilled in the art may select it according to actual conditions.

[0045] Example 1

[0046] This embodiment provides a method for preparing a copper-clad ceramic substrate, the preparation method comprising the following steps:

[0047] (1) A metal modification layer 2 with a thickness of 10 μm is coated on both sides of an aluminum nitride ceramic substrate 1 with a thickness of 0.6 mm, and then sintered at a temperature of 850° C. for 30 min under nitrogen protection;

[0048] The metal modification layer includes the following elements in terms of mass percentage: Ag 60wt%, Cu 23wt%, Ti 3wt%, Al 1wt%, and the balance is an organic carrier; the coating method is screen printing;

[0049] (2) The surface of the metal modified layer 2 sintered in step (1) is plated with a copper layer 3 having a thickness of 40 μm by screen printing, and then brazed for 30 min at a temperature of 900° C. under nitrogen protection to obtain the copper-clad ceramic substrate (such as Figure 1 shown).

[0050] Figure 2 The electron microscope characterization image of the copper-clad ceramic substrate obtained in this embodiment is Figure 2 It can be seen that the ceramic substrate has been successfully bonded to the metal modified layer and the copper layer.

[0051] Example 2

[0052] This embodiment provides a method for preparing a copper-clad ceramic substrate, the preparation method comprising the following steps:

[0053] (1) A metal modification layer with a thickness of 5 μm was coated on both sides of an aluminum nitride ceramic substrate with a thickness of 0.3 mm, and then sintered at 800° C. for 60 min under argon protection;

[0054] The metal modification layer includes the following elements in terms of mass percentage: Ag 70wt%, Cu 15wt%, Ti 3.5wt%, Al 0.5wt%, and the balance is an organic carrier; the coating method is spraying;

[0055] (2) A copper layer with a thickness of 10 μm is electroplated on the surface of the metal modified layer after the sintering treatment in step (1), and then a brazing treatment is performed for 60 minutes at a temperature of 800° C. under argon protection to obtain the copper-clad ceramic substrate.

[0056] Example 3

[0057] This embodiment provides a method for preparing a copper-clad ceramic substrate, the preparation method comprising the following steps:

[0058] (1) A metal modification layer with a thickness of 15 μm was coated on both sides of an aluminum nitride ceramic substrate with a thickness of 1 mm, and then sintered at 900° C. for 15 min under argon protection;

[0059] The metal modification layer includes the following elements in terms of mass percentage: Ag 65wt%, Cu 20wt%, Ti 4.5wt%, Al 0.5wt%, and the balance is an organic carrier; the coating method is spraying;

[0060] (2) A copper layer with a thickness of 70 μm is electroplated on the surface of the metal modified layer after the sintering treatment in step (1), and then a brazing treatment is performed for 15 minutes at a temperature of 1000° C. under argon protection to obtain the copper-clad ceramic substrate.

[0061] Example 4

[0062] This embodiment provides a method for preparing a copper-clad ceramic substrate. Except that the thickness of the metal modification layer in step (1) is 2 μm, other conditions are the same as those in Embodiment 1.

[0063] Example 5

[0064] This embodiment provides a method for preparing a copper-clad ceramic substrate. Except that the thickness of the metal modification layer in step (1) is 25 μm, other conditions are the same as those in Example 1.

[0065] Example 6

[0066] The present embodiment provides a method for preparing a copper-clad ceramic substrate. Except that in step (1), the metal modification layer includes the following elements in percentage by mass: Ag 30wt%, Cu 55wt%, Ti 3wt%, Al 1wt%, and the remainder is an organic carrier; other conditions are the same as those in Example 1.

[0067] Comparative Example 1

[0068] This comparative example provides a method for preparing a copper-clad ceramic substrate. Except that the sintering temperature in step (1) is 600° C., other conditions are the same as those in Example 1.

[0069] Comparative Example 2

[0070] This comparative example provides a method for preparing a copper-clad ceramic substrate. Except that the sintering temperature in step (1) is 1100° C., other conditions are the same as those in Example 1.

[0071] Comparative Example 3

[0072] This comparative example provides a method for preparing a copper-clad ceramic substrate. Except that step (1) is not subjected to sintering treatment, other conditions are the same as those of Example 1.

[0073] The copper-clad ceramic substrates obtained in the above examples and comparative examples were subjected to a peeling performance test, wherein the peeling performance was tested by a peeling strength tester to test the peeling strength; the test results are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] From Table 1, we can see that:

[0078] (1) The preparation method provided in Examples 1-3 of the present invention improves the bonding strength between the copper layer and the ceramic substrate by coating the metal modified layer on both sides of the ceramic substrate, then sintering and controlling the sintering temperature range, and finally brazing the copper-plated layer, thereby effectively alleviating the stress concentration between the metal thin copper layer and the ceramic substrate during the hot and cold cycle, and improving the reliability; the thermal conductivity and peel strength of the obtained copper-clad ceramic substrate are significantly improved; wherein the peel strength is ≥15N / mm;

[0079] (2) It can be seen from the comparison between Example 1 and Examples 4-5 that when the thickness of the coated metal modified layer is too thin, the reaction of the active metal modified layer is discontinuous, resulting in a decrease in the bonding strength of the obtained copper-clad ceramic substrate; when the thickness of the coated metal modified layer is too thick, although the peel strength can meet the requirements, the excess active metal modified layer flows, resulting in the modified layer overflowing from the edge of the obtained copper-clad ceramic substrate;

[0080] (3) By comparing Example 1 with Example 6, it can be seen that when the content of the Ag element in the metal modification layer is too low and the content of the Cu element is too high, the Ag-Cu eutectic line is offset and the eutectic temperature becomes higher, resulting in a decrease in the bonding strength of the obtained copper-clad ceramic substrate;

[0081] (4) By comparing Example 1 with Comparative Examples 1-3, it can be seen that when the sintering temperature is too low or no sintering is performed, an effective active metal modification layer is not formed, resulting in low bonding strength of the obtained copper-clad ceramic substrate; when the sintering temperature is too high, the copper layer melts because it exceeds the melting point of the copper layer, resulting in the copper-clad ceramic substrate not forming an effective copper cladding layer.

[0082] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a copper-clad ceramic substrate, characterized in that: The preparation method comprises the following steps: (1) coating a metal modified layer on both sides of a ceramic substrate and then performing a sintering process; The sintering temperature is 800-900°C; (2) A copper layer is plated on the surface of the metal modified layer after the sintering treatment in step (1), and then brazing is performed to obtain the copper-clad ceramic substrate.

2. The preparation method according to claim 1, characterized in that: The material of the ceramic substrate in step (1) includes any one of aluminum oxide, aluminum nitride or silicon nitride; Preferably, the thickness of the ceramic substrate in step (1) is 0.25-1 mm.

3. The preparation method according to claim 1 or 2, characterized in that: The coating method in step (1) includes any one of screen printing, spraying or roller coating, or a combination of at least two of them.

4. The preparation method according to any one of claims 1 to 3, characterized in that The thickness of the metal modification layer in step (1) is 5-15 μm.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The metal modification layer in step (1) includes the following elements: Ag, Cu and active metal elements; Preferably, the mass percentage of Ag in the metal modification layer in step (1) is 40wt%-90wt%; Preferably, the mass percentage of Cu in the metal modified layer in step (1) is 10wt%-50wt%; Preferably, the total mass percentage of Ag and Cu contained in the metal modification layer in step (1) is ≥ 82wt%; Preferably, the active metal element includes any one of Ti, Zr, Hf, Cr, V, Si or Al, or a combination of at least two of them.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The sintering process in step (1) is carried out under vacuum or inert gas protection; Preferably, the sintering time in step (1) is 10-60 minutes.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The copper plating method in step (2) includes electroplating or screen printing.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The thickness of the copper layer in step (2) is 5-75 μm.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The brazing process in step (2) is performed under vacuum or inert gas protection; Preferably, the temperature of the brazing treatment in step (2) is 800-1000°C; Preferably, the brazing treatment time in step (2) is 10-60 minutes.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) coating a metal modification layer with a thickness of 5-15 μm on both sides of a ceramic substrate with a thickness of 0.25-1 mm, and then sintering the ceramic substrate at a temperature of 800-900° C. for 10-60 min under vacuum or inert gas protection; The metal modification layer includes the following elements: Ag, Cu and active metal elements; the active metal elements include any one or a combination of at least two of Ti, Zr, Hf, Cr, V, Si or Al; The mass percentage of Ag in the metal modification layer is 40wt%-90wt%; the mass percentage of Cu in the metal modification layer is 10wt%-50wt%; the total mass of Ag and Cu in the metal modification layer is ≥82wt%; (2) A copper layer with a thickness of 5-75 μm is plated on the surface of the metal modified layer after sintering treatment in step (1), and then a brazing treatment is performed for 10-60 minutes at a temperature of 800-1000° C. under vacuum or inert gas protection to obtain the copper-clad ceramic substrate.

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