AMB ceramic substrate capable of improving reliability and process method thereof

Abstract

The invention relates to an AMB ceramic substrate capable of improving reliability and a process method thereof. The AMB ceramic substrate comprises a first copper layer, a first solder layer, a ceramic layer, a second solder layer and a second copper layer which are sequentially stacked, the AMB ceramic substrate is of an axisymmetric structure in the width direction. The width of the first solder layer is larger than that of the first copper layer, and the wider structure in the first solder layer is marked as a first step structure on one side of a symmetry axis in the width direction of the AMB ceramic substrate; the width of the second solder layer is larger than that of the second copper layer, and the wider structure in the second solder layer is marked as a second step structure on one side of the symmetry axis in the width direction of the AMB ceramic substrate. According to the AMB ceramic substrate and the manufacturing method thereof, the step structures in the first solder layer and the second solder layer can achieve gradient dispersion of stress and effectively relieve residual stress, so that the stress distribution condition is remarkably improved, and the reliability of the AMB ceramic substrate is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to an AMB ceramic substrate for improving reliability and its processing method. Background Technology

[0002] Activated Metal Brazing (AMB) has good thermal cycling properties, shape stability, high thermal conductivity, and the ability to etch various patterns onto the copper surface. It has a wide operating temperature range and a thermal expansion coefficient close to that of silicon. Its applications are very broad, including semiconductor coolers, electronic heaters, high-power semiconductor modules, power control circuits, power hybrid circuits, smart power components, and many other semiconductor fields.

[0003] As a commonly used electronic packaging material in power semiconductor modules, the thermal shock performance of active brazed copper-clad laminates determines the overall lifespan of the power semiconductor module. Therefore, improving the thermal shock performance of AMB copper-clad ceramic substrates is of great significance for the packaging of power semiconductor modules.

[0004] CN114853497A discloses an active metal brazing copper-clad ceramic substrate and its preparation method. The preparation method includes the following steps: Step 1: Setting positioning reference holes on the ceramic substrate; ultrasonically washing in a cleaning agent and drying to obtain ceramic substrate A; Step 2: Pre-patterning and coating active metal solder on ceramic substrate A, drying to obtain an active metal solder layer; fixing copper sheets on the active metal solder layer and vacuum brazing to obtain ceramic substrate C; Step 3: Patterning ceramic substrate C and removing excess copper layer to obtain a copper-clad ceramic substrate. This copper-clad ceramic substrate exhibits a cycle life of only about 1500 cycles in cyclic thermal shock performance testing.

[0005] CN115719709A discloses a method for improving the reliability of copper-clad ceramic substrates. The copper-clad ceramic substrate includes a front copper layer, a ceramic layer, and a back copper layer arranged sequentially from top to bottom. The copper foil of the front copper layer has stepped grooves along its edges, with the cross-sectional area of ​​the copper foil increasing in a stepped manner from top to bottom. The stepped grooves can be a single-layer groove structure or a double-layer groove structure arranged vertically. In reliability tests, the highest reliability of this copper-clad ceramic substrate is only slightly over 500 cycles.

[0006] In summary, the structure of the AMB ceramic substrate needs to be improved to enhance its thermal shock resistance and reliability. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides an AMB ceramic substrate with improved reliability and its processing method. By adjusting the width relationship between the solder layer and the copper layer, this invention creates a stepped structure in the first and second solder layers to achieve gradient stress dispersion, alleviate residual stress, and thus significantly improve the stress distribution and enhance the reliability of the AMB ceramic substrate.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an AMB ceramic substrate for improving reliability, the AMB ceramic substrate comprising a first copper layer, a first solder layer, a ceramic layer, a second solder layer and a second copper layer stacked sequentially.

[0010] The AMB ceramic substrate has an axisymmetric structure in the width direction;

[0011] The width of the first solder layer is greater than the width of the first copper layer. Along the width direction of the AMB ceramic substrate, on one side of the axis of symmetry, the structure that extends out in the first solder layer is called the first step structure.

[0012] The width of the second solder layer is greater than the width of the second copper layer. Along the width direction of the AMB ceramic substrate, on one side of the axis of symmetry, the structure that extends out in the second solder layer is called the second step structure.

[0013] The etched patterns on existing AMB ceramic substrates are prone to stress concentration at the edges, leading to preferential failure at these edges in practical applications and affecting the overall lifespan of the AMB ceramic substrate. Therefore, this invention improves the structure of the AMB ceramic substrate by making the width of the solder layer greater than the thickness of the copper layer, thus forming a stepped structure in the solder layer. This stepped structure can achieve gradient stress dispersion, alleviate residual stress, and significantly improve the stress distribution, thereby enhancing the reliability of the AMB ceramic substrate.

[0014] It should be noted that this invention is an improvement on existing AMB ceramic substrates in the art. The size of the AMB ceramic substrate can be selected by those skilled in the art as needed, and is not specifically limited here.

[0015] As a preferred embodiment of the present invention, the size of the first copper layer is equal to the size of the second copper layer.

[0016] As a preferred embodiment of the present invention, the first solder layer and the second solder layer have the same dimensions.

[0017] Preferably, the width of the first step structure is 0.05~0.15mm, for example, it can be 0.05mm, 0.07mm, 0.1mm, 0.12mm or 0.15mm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0018] This invention, by limiting the width of the first and second step structures to 0.05~0.15mm, can achieve gradient dispersion of stress, alleviate residual stress, thereby improving stress distribution and enhancing the reliability of the AMB ceramic substrate. If the width of the step structure is less than 0.05mm, it will lead to stress concentration at the edge of the etched pattern of the AMB ceramic substrate, thus affecting the reliability of the AMB ceramic substrate. If the width of the step structure is greater than 0.15mm, it will affect the pattern design, reduce the conductive cross-sectional area, and affect the heat dissipation performance and current carrying capacity of the AMB ceramic substrate.

[0019] Preferably, the lengths of the first copper layer, the first solder layer, and the ceramic layer are equal.

[0020] As a preferred technical solution of the present invention, the thickness of the first copper layer is 0.3~1mm, for example, it can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0021] As a preferred technical solution of the present invention, the thickness of the first solder layer is 5~20μm, for example, it can be 5μm, 8μm, 10μm, 12μm, 15μm or 20μm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] As a preferred technical solution of the present invention, the thickness of the ceramic layer is 0.2~1mm, for example, it can be 0.2mm, 0.25mm, 0.32mm, 0.38mm, 0.5mm, 0.635mm or 1mm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0023] Preferably, the first copper layer is concave-arc shaped near the first step structure.

[0024] This invention defines the copper layer in the AMB ceramic substrate as concave-arc near the stepped structure, so that there are no sharp stress concentration points at the connection between the copper layer and the solder layer, thereby reducing the stress concentration coefficient, improving the stress distribution, and enhancing the reliability of the AMB ceramic substrate.

[0025] As a preferred embodiment of the present invention, the material of the ceramic layer includes any one of silicon nitride, aluminum oxide, or aluminum nitride.

[0026] In a second aspect, the present invention provides a process method for improving the reliability of an AMB ceramic substrate according to the first aspect, the process method comprising the following steps:

[0027] The sintered copper-clad ceramic substrate is sequentially patterned and post-processed to obtain the AMB ceramic substrate.

[0028] The patterning process includes sequential application of film, exposure, and development.

[0029] The post-processing includes any one or a combination of at least two of etching, laser ablation, or mechanical milling, wherein typical but non-limiting combinations include: a combination of etching and laser ablation, a combination of etching and mechanical milling, a combination of laser ablation and mechanical milling, and a combination of etching, laser ablation, and mechanical milling.

[0030] The present invention directly performs patterning and post-processing on the sintered ceramic copper-clad laminate to obtain the AMB ceramic substrate. The preparation method provided by the present invention is simple and easy to scale up industrially.

[0031] It should be noted that the sintered ceramic copper-clad laminate in this invention is a commonly used ceramic copper-clad laminate in the art, and the film application, exposure and development in this invention are commonly used patterning processing methods in the art. Those skilled in the art can choose according to their needs, and no specific limitation is made here.

[0032] As a preferred technical solution of the present invention, the material of the ceramic layer in the sintered ceramic copper-clad plate includes any one of silicon nitride, aluminum oxide, or aluminum nitride.

[0033] As a preferred technical solution of the present invention, the process method includes the following steps:

[0034] (1) The sintered ceramic copper-clad laminate is sequentially subjected to a patterning process of film application, exposure and development to obtain a patterned ceramic copper-clad laminate; wherein, the material of the ceramic layer in the sintered ceramic copper-clad laminate includes any one of silicon nitride, aluminum oxide or aluminum nitride.

[0035] (2) The patterned ceramic copper-clad laminate is post-processed to obtain the AMB ceramic substrate;

[0036] The post-processing includes any one or a combination of at least two of etching, laser ablation, or mechanical milling.

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

[0038] (1) By improving the structure of the AMB ceramic substrate and adjusting the width relationship between the solder layer and the copper layer, the present invention makes a stepped structure in the first solder layer and the second solder layer to achieve stress gradient dispersion, thereby significantly improving the stress distribution and improving the reliability of the AMB ceramic substrate. The AMB ceramic substrate of the present invention can reach more than 2000 cycles in the cyclic thermal shock performance test.

[0039] (2) The preparation method provided by the present invention is simple and easy to scale up industrially. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the AMB ceramic substrate provided in Embodiment 1 of the present invention.

[0041] Figure 2 This is a schematic diagram of the structure of the AMB ceramic substrate provided in Comparative Example 1 of the present invention.

[0042] Wherein, 1-first copper layer; 2-first solder layer; 3-ceramic layer; 4-second solder layer; 5-second copper layer; 6-first step structure; 7-second step structure. Detailed Implementation

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0044] Example 1

[0045] This embodiment provides an AMB ceramic substrate for improved reliability, such as... Figure 1 As shown, the AMB ceramic substrate includes a first copper layer 1, a first solder layer 2, a ceramic layer 3, a second solder layer 4, and a second copper layer 5 stacked sequentially.

[0046] The first copper layer 1, the first solder layer 2, and the ceramic layer 3 are of equal length, and the size of the first copper layer 1 is equal to the size of the second copper layer 5. The size of the first solder layer 2 and the second solder layer 4 are equal. The thickness of the ceramic layer 3 is 0.32 mm; the thickness of the first solder layer 2 is 10 μm; and the thickness of the first copper layer 1 is 0.8 mm.

[0047] The AMB ceramic substrate has an axisymmetric structure in the width direction. Compared to the first copper layer 1, along the width direction of the AMB ceramic substrate, on one side of the axis of symmetry, the structure that extends out in the first solder layer 2 is called the first step structure 6. The width of the first step structure 6 is 0.1 mm. The first copper layer 1 is concave arc-shaped near the first step structure. Similarly, compared to the second copper layer 5, the structure that extends out in the second solder layer 4 is called the second step structure 7.

[0048] The ceramic layer 3 is made of silicon nitride.

[0049] This embodiment also provides a process method for improving the reliability of AMB ceramic substrates, the process method including the following steps:

[0050] (1) The sintered ceramic copper-clad laminate is sequentially subjected to patterning processes of film lamination, exposure and development to obtain a patterned ceramic copper-clad laminate; wherein, the material of the ceramic layer in the sintered ceramic copper-clad laminate is silicon nitride.

[0051] (2) The patterned ceramic copper-clad laminate is etched to obtain the AMB ceramic substrate.

[0052] Example 2

[0053] This embodiment provides an AMB ceramic substrate for improving reliability. The AMB ceramic substrate includes a first copper layer 1, a first solder layer 2, a ceramic layer 3, a second solder layer 4, and a second copper layer 5 stacked sequentially.

[0054] The first copper layer 1, the first solder layer 2, and the ceramic layer 3 are of equal length, and the size of the first copper layer 1 is equal to the size of the second copper layer 5. The size of the first solder layer 2 and the second solder layer 4 are equal. The thickness of the ceramic layer 3 is 0.32 mm; the thickness of the first solder layer 2 is 5 μm; and the thickness of the first copper layer 1 is 1 mm.

[0055] The AMB ceramic substrate has an axisymmetric structure in the width direction; and compared to the first copper layer 1, along the width direction of the AMB ceramic substrate, on one side of the axis of symmetry, the structure that extends out in the first solder layer 2 is called the first step structure 6, the width of the first step structure 6 is 0.05mm, and the first copper layer 1 is concave arc-shaped near the first step structure. Similarly, compared to the second copper layer 5, the structure that extends out in the second solder layer 4 is called the second step structure 7.

[0056] The ceramic layer 3 is made of silicon nitride.

[0057] This embodiment also provides a process method for improving the reliability of AMB ceramic substrates, the process method including the following steps:

[0058] (1) The sintered ceramic copper-clad laminate is sequentially subjected to patterning processes of film lamination, exposure and development to obtain a patterned ceramic copper-clad laminate; wherein, the material of the ceramic layer in the sintered ceramic copper-clad laminate is silicon nitride.

[0059] (2) The patterned ceramic copper-clad laminate is subjected to laser ablation to obtain the AMB ceramic substrate.

[0060] Example 3

[0061] This embodiment provides an AMB ceramic substrate for improving reliability. The AMB ceramic substrate includes a first copper layer 1, a first solder layer 2, a ceramic layer 3, a second solder layer 4, and a second copper layer 5 stacked sequentially.

[0062] The first copper layer 1, the first solder layer 2, and the ceramic layer 3 are of equal length, and the size of the first copper layer 1 is equal to the size of the second copper layer 5. The size of the first solder layer 2 and the second solder layer 4 are equal. The thickness of the ceramic layer 3 is 0.25 mm. The thickness of the first solder layer 2 is 20 μm. The thickness of the first copper layer 1 is 0.4 mm.

[0063] The AMB ceramic substrate has an axisymmetric structure in the width direction; and compared to the first copper layer 1, along the width direction of the AMB ceramic substrate, on one side of the axis of symmetry, the structure that extends out in the first solder layer 2 is called the first step structure 6, the width of the first step structure 6 is 0.15mm, and the first copper layer 1 is concave arc-shaped near the first step structure. Similarly, compared to the second copper layer 5, the structure that extends out in the second solder layer 4 is called the second step structure 7.

[0064] The ceramic layer 3 is made of silicon nitride.

[0065] This embodiment also provides a process method for improving the reliability of AMB ceramic substrates, the process method including the following steps:

[0066] (1) The sintered ceramic copper-clad laminate is sequentially subjected to patterning processes of film lamination, exposure and development to obtain a patterned ceramic copper-clad laminate; wherein, the material of the ceramic layer in the sintered ceramic copper-clad laminate is silicon nitride.

[0067] (2) The patterned ceramic copper-clad laminate is mechanically milled to obtain the AMB ceramic substrate.

[0068] Example 4

[0069] This embodiment provides an AMB ceramic substrate with improved reliability. The only difference from Embodiment 1 is that the material of the ceramic layer is changed from silicon nitride to aluminum oxide, the thickness of the ceramic layer is adjusted to 0.38 mm, and the thickness of the first copper layer is adjusted to 0.3 mm. All other aspects are the same as in Embodiment 1.

[0070] Example 5

[0071] This embodiment provides an AMB ceramic substrate with improved reliability. The only difference from Embodiment 1 is that the material of the ceramic layer is changed from silicon nitride to aluminum nitride, the thickness of the ceramic layer is adjusted to 0.635 mm, and the thickness of the first copper layer is adjusted to 0.3 mm. All other aspects are the same as in Embodiment 1.

[0072] Example 6

[0073] This embodiment provides an AMB ceramic substrate with improved reliability. The only difference from Embodiment 1 is that the widths of the first and second step structures are adjusted from 0.1 mm to 0.02 mm. All other aspects are the same as in Embodiment 1.

[0074] Example 7

[0075] This embodiment provides an AMB ceramic substrate with improved reliability. The only difference from Embodiment 1 is that the widths of the first and second step structures are adjusted from 0.1 mm to 0.2 mm. All other aspects are the same as in Embodiment 1.

[0076] Example 8

[0077] This embodiment provides an AMB ceramic substrate with improved reliability. The only difference from Embodiment 1 is that the shapes of the first copper layer and the second copper layer are adjusted to be rectangular, while the rest are the same as in Embodiment 1.

[0078] Comparative Example 1

[0079] This comparative example provides an AMB ceramic substrate with improved reliability. The only difference from Example 1 is that the width of the first solder layer is equal to the width of the first copper layer near the first solder layer, and the width of the second solder layer is equal to the width of the second copper layer near the second solder layer. That is, the AMB ceramic substrate does not have a first step structure and a second step structure. All other aspects are the same as in Example 1.

[0080] The structural schematic diagram of the AMB ceramic substrate provided in this comparative example is shown below. Figure 2 As shown.

[0081] Cyclic thermal shock performance tests were conducted on the AMB ceramic substrates obtained in Examples 1-8 and Comparative Example 1 (temperature 150℃ / -55℃; each cycle was held at high and low temperatures for 15 min, and the transition time was ≤5 min). The test results are shown in Table 1.

[0082] Table 1

[0083]

[0084] The test results show that:

[0085] (1) As can be seen from Examples 1 to 5, the present invention improves the structure of the AMB ceramic substrate and adjusts the width relationship between the solder layer and the copper layer so that there is a stepped structure in the first solder layer and the second solder layer to achieve stress gradient dispersion. When the material of the ceramic layer in the AMB ceramic substrate is silicon nitride, the number of cycles in the cyclic thermal shock performance test of the AMB ceramic substrate can reach more than 2000 times. When the materials of the ceramic layer in the AMB ceramic substrate are alumina and aluminum nitride, the corresponding number of cycles in the cyclic thermal shock performance test of the AMB ceramic substrate can reach 300 times and 400 times, respectively. It can be seen that the thermal shock performance of the AMB ceramic substrate is different depending on the material of the ceramic layer. This is because the thermal shock performance of the AMB ceramic substrate is related to the bending strength of the ceramic layer.

[0086] (2) As can be seen from Examples 1 and 6-7, the width of the step structure in Example 1 is 0.1 mm, and the AMB ceramic substrate obtained therefrom has 2200 cycles in the thermal shock performance test; while the width of the step structure in Example 4 is 0.02 mm, and the AMB ceramic substrate obtained therefrom has 1500 cycles in the thermal shock performance test; and the width of the step structure in Example 5 is 0.2 mm, and the AMB ceramic substrate obtained therefrom has 2000 cycles in the thermal shock performance test. This shows that by limiting the width of the step structure, the present invention can further achieve stress gradient dispersion, alleviate residual stress, thereby improving the stress distribution and improving the reliability of the AMB ceramic substrate.

[0087] (3) As can be seen from Examples 1 and 8, in Example 1, the copper layer near the step structure is concave arc-shaped, and the resulting AMB ceramic substrate has a cycle count of 2200 times in the thermal shock performance test; while in Example 6, the copper layer is rectangular, and the resulting AMB ceramic substrate has a cycle count of 1600 times in the thermal shock performance test. This shows that by designing the structure of the copper layer, the present invention can further achieve stress gradient dispersion, alleviate residual stress, thereby improving stress distribution and enhancing the reliability of the AMB ceramic substrate.

[0088] (4) As can be seen from Example 1 and Comparative Example 1, the present invention improves the structure of the AMB ceramic substrate so that the width of the solder layer is greater than the width of the copper layer, and so that there is a stepped structure in the solder layer to achieve stress gradient dispersion, thereby improving the reliability of the AMB ceramic substrate.

[0089] In summary, this invention improves the structure of the AMB ceramic substrate by adjusting the width relationship between the solder layer and the copper layer, resulting in a stepped structure in the first and second solder layers to achieve stress gradient dispersion. This significantly improves the stress distribution and enhances the reliability of the AMB ceramic substrate. The AMB ceramic substrate of this invention can withstand more than 2000 cycles in cyclic thermal shock performance testing.

[0090] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An AMB ceramic substrate for improving reliability, characterized in that, The AMB ceramic substrate includes a first copper layer, a first solder layer, a ceramic layer, a second solder layer, and a second copper layer stacked sequentially. The AMB ceramic substrate has an axisymmetric structure in the width direction; The width of the first solder layer is greater than the width of the first copper layer. Along the width direction of the AMB ceramic substrate, on one side of the axis of symmetry, the structure that extends out in the first solder layer is called the first step structure. The width of the second solder layer is greater than the width of the second copper layer. Along the width direction of the AMB ceramic substrate, on one side of the axis of symmetry, the structure that extends out in the second solder layer is called the second step structure.

2. The AMB ceramic substrate according to claim 1, characterized in that, The dimensions of the first copper layer are equal to the dimensions of the second copper layer.

3. The AMB ceramic substrate according to claim 2, characterized in that, The first solder layer and the second solder layer have the same dimensions; Preferably, the width of the first step structure is 0.05~0.15mm.

4. The AMB ceramic substrate according to claim 2, characterized in that, The thickness of the first copper layer is 0.3~1mm.

5. The AMB ceramic substrate according to claim 3, characterized in that, The thickness of the first solder layer is 5~20μm.

6. The AMB ceramic substrate according to any one of claims 1-5, characterized in that, The thickness of the ceramic layer is 0.2~1mm.

7. The AMB ceramic substrate according to any one of claims 1-6, characterized in that, The ceramic layer is made of any one of silicon nitride, aluminum oxide, or aluminum nitride.

8. A process method for improving the reliability of an AMB ceramic substrate according to any one of claims 1-7, characterized in that, The process includes the following steps: The sintered copper-clad ceramic substrate is sequentially patterned and post-processed to obtain the AMB ceramic substrate. The patterning process includes sequential application of film, exposure, and development. The post-processing includes any one or a combination of at least two of etching, laser ablation, or mechanical milling.

9. The process method according to claim 8, characterized in that, The material of the ceramic layer in the sintered copper-clad ceramic plate includes any one of silicon nitride, aluminum oxide, or aluminum nitride.

10. The process method according to claim 8 or 9, characterized in that, The process includes the following steps: (1) The sintered ceramic copper-clad laminate is sequentially subjected to a patterning process of film application, exposure and development to obtain a patterned ceramic copper-clad laminate; wherein, the material of the ceramic layer in the sintered ceramic copper-clad laminate includes any one of silicon nitride, aluminum oxide or aluminum nitride. (2) The patterned ceramic copper-clad laminate is post-processed to obtain the AMB ceramic substrate; The post-processing includes any one or a combination of at least two of etching, laser ablation, or mechanical milling.

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