Double-sided active metal bonding substrate and method for manufacturing the same

Abstract

To provide a double-sided active metal bonding substrate and a method for manufacturing the same for solving the disadvantages of the existing technology. 【Solution means】The double-sided active metal bonding substrate includes a ceramic substrate layer, first and second holding walls, first and second active metal layers, and first and second conductive metal layers. The first active metal layer is disposed on the first surface of the ceramic substrate layer. The first active metal layer is surrounded by the first holding wall and contacts the first holding wall. The first conductive metal layer is disposed on the first active metal layer. The second active metal layer is disposed on the second surface of the ceramic substrate layer. The second active metal layer is surrounded by the second holding wall and contacts the second holding wall. The second conductive metal layer is disposed on the second active metal layer. Due to the structural design that the thickness of the holding wall is smaller than the thickness of the active metal layer, it is possible to prevent solder from overflowing.

Description

Technical Field

[0001] The present invention relates to a double-sided active metal bonding substrate and a method for manufacturing the same, and more particularly to a double-sided active metal bonding substrate having a highly precise patterned circuit and a method for manufacturing the same.

Background Art

[0002] Electric vehicles are being pushed forward by the growing global awareness of energy conservation and carbon reduction, as well as the policies of various countries, and have become one of the major research and development projects of automobile manufacturers. In recent years, automobile manufacturers have launched a series of 800V high-voltage vehicle models, which has also driven the demand for the characteristics of substrate materials.

[0003] Under operating conditions of high voltage, high frequency, and high operating temperature, ceramic substrates have higher reliability and heat dissipation capabilities than substrates made of other materials. Conventionally, the most widely used ceramic substrate was a direct-bonding-copper (DBC) ceramic substrate. However, conventional DBC ceramic substrates have not been able to meet the packaging requirements of high temperature, high power, high heat dissipation, and high reliability. Therefore, the current mainstream substrate material is gradually shifting from DBC ceramic substrates to active metal bonding (active metal brazing, AMB) substrates.

[0004] In the manufacturing process of the AMB substrate, first, a solder layer is formed on the surface of the ceramic substrate. A copper layer is coated and then joined (bonded) to the substrate by a sintering process. Thereafter, a patterned circuit is formed on the ceramic substrate by more than three etching processes. Alternatively, a patterned active metal solder may be printed on the surface of the ceramic substrate. A copper layer is coated and then joined to the substrate by a sintering process. Next, the copper layer is etched to form a patterned circuit. The method of forming the patterned active metal solder can not only save the solder in the inert pattern area and reduce the cost, but also save the process cost of the subsequent secondary etching of the solder.

[0005] During the high-temperature sintering process, the patterned metal solder is easy to flow. If the solder overflows into the area without a pattern, the solder will cause a short circuit. Finally, the second etching performed to remove the solder that has overflowed into the gap between the patterns does not save the etching cost, reduces the overall pattern accuracy of the circuit, and thereby affects the product quality.

[0006] Therefore, improving the structural design and manufacturing method to prevent the overflow of solder in the sintering process and overcome the above disadvantages has become one of the important issues to be solved in this technical field.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] One object of the present invention is to provide a dual-active-metal bonding substrate and a method for manufacturing the same to solve the drawbacks of existing technologies.

Means for Solving the Problems

[0009] One aspect of the present invention is a dual-active-metal bonding substrate, comprising a ceramic substrate layer having a first surface and a second surface, a first active metal layer disposed on the first surface, a second active metal layer disposed on the second surface, a first retaining wall surrounding and contacting the first active metal layer, wherein the thickness of the first retaining wall is smaller than the thickness of the first active metal layer, a second retaining wall surrounding and contacting the second active metal layer, wherein the thickness of the second retaining wall is smaller than the thickness of the second active metal layer, a first conductive metal layer disposed on the first active metal layer, and a second conductive metal layer disposed on the second active metal layer.

[0010] According to some embodiments, the thickness ratio of the first retaining wall to the first active metal layer is 0.10 to 0.95.

[0011] According to some embodiments, the first retaining wall contains aluminum oxide, magnesium oxide, zirconium oxide, silicon oxide, aluminum nitride, or silicon nitride.

[0012] According to some embodiments, the thickness of the first retaining wall is 1 to 5 micrometers.

[0013] According to some embodiments, the width of the first retaining wall is 0.1 mm to 30 mm.

[0014] According to some embodiments, the thickness of the first active metal layer is 10 to 50 micrometers.

[0015] Another aspect of the present invention is a method for manufacturing a double-sided active metal bonding substrate, comprising the steps of performing a patterning process to form a first retaining wall on a first surface of a ceramic substrate layer and a second retaining wall on a second surface of the ceramic substrate layer, wherein the first retaining wall defines a first patterned region and the second retaining wall defines a second patterned region; forming a first active metal layer in the first patterned region and a second active metal layer in the second patterned region; disposing a first conductive metal layer on the first active metal layer and a second conductive metal layer on the second active metal layer; and performing a soldering process to fix the first conductive metal layer to the ceramic substrate layer and the second active metal layer to the ceramic substrate layer. The thickness of the first retaining wall is smaller than the thickness of the first active metal layer, and the thickness of the second retaining wall is smaller than the thickness of the second active metal layer.

[0016] According to some embodiments, the sintering temperature in the soldering process is 800-950 °C.

[0017] According to some embodiments, the sintering pressure in the soldering process is less than 8×10 -5 Torr.

[0018] According to some embodiments, the tensile strength of the double-sided active metal bonding substrate is greater than 100 N / cm.

Advantages of the Invention

[0019] One of the beneficial effects of the present invention is that, by means of the technical solution of "retaining wall" and "the thickness of the retaining wall is smaller than the thickness of the active metal layer", the double-sided active metal bonding substrate provided by the present invention and its manufacturing method can prevent the solder from overflowing at high temperatures, thereby improving the bonding force between the ceramic substrate layer and the conductive metal layer.

[0020] These and other objects of the present invention will become apparent to those skilled in the art after reading the following detailed description of the preferred embodiments shown in the various figures and drawings.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0022] The following is a specific example for explaining the implementation of the "double-sided active metal bonding substrate and its manufacturing method" disclosed in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention may be implemented or applied by other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are merely schematic, and it should be stated in advance that they are not depictions based on actual dimensions. The following embodiments further explain the related technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of the present invention. In addition, the term "or" used in this specification includes any one or a combination of a plurality of listed items associated therewith according to the actual situation.

[0023] In order to prevent the solder from overflowing from the edge of the pattern into the area without the pattern during the sintering process, a retaining wall is arranged on the ceramic substrate layer to define the patterned area, and then an active metal solder is formed in the patterned area, which is a technical feature of the present invention. The retaining wall can prevent the active metal solder from overflowing during the soldering process, ensure that the double-sided active metal bonding substrate has a high-precision circuit pattern, and eliminate the need for secondary etching of excess solder.

[0024] Controlling the thickness of the retaining wall is another technical feature of the present invention. According to the experimental results, in a high-temperature environment, the material of the retaining wall may react with the active metal solder, which may have an adverse effect on the bonding strength between the active metal solder and the subsequent conductive metal layer. Therefore, by controlling the thickness of the retaining wall, the double-sided active metal bonding substrate can have higher tensile strength.

[0025] In the present disclosure, the double-sided active metal bonding substrate means that conductive metal layers are provided on both sides (opposite surfaces) of the substrate. Note that the conductive metal layers on both sides may have the same pattern or different patterns. For example, the conductive metal layer on one side can be used as a circuit layer, and the conductive metal layer on the other side can be used as a heat dissipation layer. Alternatively, the conductive metal layers on both sides can be used as circuit layers. However, the present invention is not limited thereto.

[0026] Referring to FIG. 1. The double-sided active metal bonding substrate of the present invention includes a ceramic substrate layer 1, a first retaining wall 2, a second retaining wall 2', a first active metal layer 3, a second active metal layer 3', a first conductive metal layer 4, and a second conductive metal layer 4'.

[0027] The first retaining wall 2, the first active metal layer 3, and the first conductive metal layer 4 are arranged on the first surface 11 of the ceramic substrate layer 1, and the second retaining wall 2', the second active metal layer 3', and the second conductive metal layer 4' are arranged on the second surface 11' of the ceramic substrate layer 1. Hereinafter, the structure of each layer of the double-sided active metal bonding substrate will be described.

[0028] <Ceramic substrate layer> The ceramic substrate layer 1 is a substrate that can be used to carry a double-sided printing structure, and can include a silicon nitride (Si3N4) ceramic substrate, a silicon carbide (SiC) ceramic substrate, an aluminum nitride (AlN) ceramic substrate, or an aluminum oxide (Al2O3) ceramic substrate, preferably a silicon-containing ceramic substrate, more preferably a silicon nitride ceramic substrate. In addition, the thickness of the ceramic substrate layer 1 may be 0.25 mm to 1 mm, but is not limited thereto.

[0029] <Retention wall> The retention wall is disposed on the ceramic substrate layer 1. The retention wall can define a patterned region on the ceramic substrate layer 1. This patterned region can be designed or adjusted according to the pattern structures of the active metal layer and the conductive metal layer.

[0030] In the structure shown in FIG. 1, the first retention wall 2 is disposed on the first surface 11 and defines a patterned region. The range of the patterned region can be designed or adjusted according to the pattern structures of the first active metal layer 3 and the first conductive metal layer 4. Similarly to the first retention wall 2, the second retention wall 2' is disposed on the second surface 11' and defines another patterned region. The range of this patterned region can be designed or adjusted according to the pattern structures of the second active metal layer 3' and the second conductive layer 4'.

[0031] Since the conductive metal layers on both sides of the ceramic substrate layer may have the same pattern or different patterns, the patterned region defined by the first retention wall 2 may be the same as or different from the patterned region defined by the second retention wall 2'.

[0032] The retention wall can prevent the active metal layer from overflowing from the patterned region in a high-temperature environment (such as a brazing process) when manufacturing a double-sided active metal bonding substrate having a high-precision patterned circuit.

[0033] To prevent the active metal layer from overflowing from the patterned region, the retaining wall is made of a material with high heat resistance, and the material of the retaining wall has low affinity with the material of the active metal layer. Even if the molten active metal layer material comes into contact with the retaining wall, due to its large aggregation, the active metal layer material does not accumulate beyond the patterned region defined by the retaining wall.

[0034] Specifically, the material of the retaining wall may be aluminum oxide (Al2O3), magnesium oxide (MgO), zirconium oxide (ZrO2), silicon dioxide (SiO2), aluminum nitride (AlN), or silicon nitride (Si3N4). For example, the retaining wall can be composed of particles of the above-mentioned high heat resistance material. The retaining wall composed of particles can reduce the affinity between the material of the retaining wall and the material of the active metal layer. For example, the average particle size (particle diameter) of the particles is less than 12 micrometers. In an exemplary embodiment, the average particle size of the particles is 3 to 12 micrometers, for example, a positive integer between 3 and 12 micrometers.

[0035] Furthermore, to achieve a good barrier effect, the width of the retaining wall can be further controlled. When the width of the retaining wall is wide, it becomes more difficult for the active metal layer material to cross the retaining wall beyond the patterned region. In an exemplary embodiment, the width of the retaining wall is 0.1 mm to 30 mm. For example, the width of the retaining wall may be a positive integer between 0.1 mm and 30 mm.

[0036] Regarding the thickness of the retaining wall, experimental results indicate that in a high-temperature environment, the material of the retaining wall may react with the material of the active metal layer at the contact surface or may diffuse onto the upper surface of the active metal layer.

[0037] Specifically, the original purpose of the active metal layer is to combine with the conductive metal layer. However, if the material of the active metal layer reacts with the material of the retention wall or diffuses to the contact surface between the active metal layer and the conductive metal layer, the bonding force between the material of the active metal layer and the material of the conductive metal layer may decrease. Therefore, in order to prevent the active metal layer from overflowing from the patterned area without reducing the bonding force of the conductive metal layer, further controlling the thickness of the retention wall to be smaller than the thickness of the active metal layer is another technical feature of the present invention.

[0038] To facilitate the definition of the thickness of each layer, in the present disclosure, the thickness of the first retention wall 2 and the thickness of the first active metal layer 3 refer to the direction perpendicular to the first surface 11. The thickness of the second retention wall 2' and the thickness of the second active metal layer 3' refer to the direction perpendicular to the second surface 11'.

[0039] Further, the present invention can improve the pattern circuit accuracy of the double-sided active metal bonding substrate without adversely affecting the bonding force between the material of the active metal layer and the material of the conductive metal layer by controlling the thickness ratio of the retention wall to the active metal layer. Specifically, the thickness ratio of the first retention wall 2 to the first active metal layer 3 is 0.10 to 0.95. For example, the thickness ratio of the first retention wall 2 to the first active metal layer 3 may be 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85 or 0.90. The thickness ratio of the second retention wall 2' to the second active metal layer 3' is 0.10 to 0.95. For example, the thickness ratio of the second retention wall 2' to the second active metal layer 3' may be 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85 or 0.90.

[0040] In an exemplary embodiment, the thickness of the first retention wall 2 is 1 to 5 micrometers, and the thickness of the second retention wall 2' is 1 to 5 micrometers.

[0041] To achieve the above thickness design of the retaining wall, the retaining wall can be disposed on the ceramic substrate layer 1 by screen printing. However, the way of disposing the retaining wall is not limited thereto. As long as the thickness of the retaining wall can be made thinner than the thickness of the active metal layer, the method can be applied to the present invention.

[0042] <Active metal layer> The active metal layer is disposed in a patterned region defined by the retaining wall, and the active metal layer is disposed between the ceramic substrate layer 1 and the conductive metal layer to fix the conductive metal layer on the ceramic substrate layer 1.

[0043] In the structure shown in FIG. 1, the first active metal layer 3 is disposed within a patterned region defined by the first retaining wall 2, that is, the first retaining wall 2 surrounds the first active metal layer 3. To more accurately control the shape of the circuit layer, the first retaining wall 2 can be brought into contact with the side surface of the first active metal layer 3 to prevent the active metal solder from overflowing from the patterned region under a high-temperature environment.

[0044] Similar to the first active metal layer 3, the second active metal layer 3' is disposed within a patterned region defined by the second retaining wall 2', that is, the second retaining wall 2' surrounds the second active metal layer 3'. Furthermore, the second retaining wall 2' can be brought into contact with the side surface of the second active metal layer 3' to prevent the active metal solder from overflowing from the patterned region under a high-temperature environment.

[0045] The active metal layer is formed from an active metal solder paste. The active metal solder paste contains an active metal solder and an organic dispersion medium, and the active metal solder is dispersed in the organic dispersion medium. Under high-temperature conditions, the active metal solder can form an alloy with the material of the ceramic substrate layer and can also form an alloy with the material of the conductive metal layer to achieve a joining effect.

[0046] The active metal solder contains metallic silver (Ag), metallic copper (Cu), and an active metal. Specifically, the active metal may be 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). In a preferred embodiment, the active metal solder contains metallic silver (Ag), metallic copper (Cu), and metallic titanium (Ti). In a high-temperature environment (soldering process), some metals can diffuse into the ceramic substrate to form metal silicon compounds or metal nitrogen compounds, and some metals can also diffuse into the conductive metal layer to form alloys, enhancing the mutual bonding effect.

[0047] As described above, by coating the patterned region surrounded by the retaining wall with the active metal layer and controlling the thickness of the active metal layer to be greater than the thickness of the retaining wall, the double-sided active metal bonding substrate of the present invention can have higher tensile strength.

[0048] As the thickness of the active metal layer increases, the bonding force between the ceramic substrate layer and the conductive metal layer also increases. However, if the thickness of the active metal layer is too thick, the material cost of the active metal layer becomes too high, which does not contribute to mass production. Therefore, the thickness of the active metal layer 2 is 6 micrometers or more. If the thickness of the active metal layer is not smaller than the retaining wall and does not cause process cost problems, the thickness of the active metal layer can be 10 - 50 micrometers. For example, the thickness of the active metal layer 2 may be a positive integer between 10 - 50 micrometers.

[0049] <Conductive metal layer> The conductive metal layer is disposed on the active metal layer. Since the bonding force between the conductive metal layer and the ceramic substrate layer 1 is weak, the conductive metal layer needs to be disposed on the ceramic substrate layer via the active metal layer.

[0050] Through different structural designs, the conductive metal layer can be used as the circuit layer or heat dissipation layer of the active metal bonding substrate. When used as the circuit layer, the pattern accuracy of the conductive metal layer has a great impact on the quality of the double-sided active metal bonding substrate.

[0051] In the structure shown in FIG. 1, the first conductive metal layer 4 is fixed on the first surface 11 of the ceramic substrate layer 1 through the first active metal layer 3. The pattern structure of the first conductive metal layer 4 corresponds to the pattern structure of the first active metal layer 3. Similarly to the first conductive metal layer 4, the second conductive metal layer 4' is disposed on the second surface 11' of the ceramic substrate layer 1 through the second active metal layer 3'. The pattern structure of the second conductive metal layer 4' corresponds to the pattern structure of the first conductive metal layer 4'.

[0052] Specifically, the conductive metal layer may be a metal copper foil, a metal aluminum foil, or a copper-aluminum alloy foil. In a preferred embodiment, the conductive metal layer is a metal copper foil.

[0053] Since the bonding force between the ceramic substrate layer and the conductive metal layer of the present invention is better, a thicker conductive metal layer can be soldered, and the thickness of the conductive metal layer can be 0.2 mm to 1.5 mm, for example, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, or 1.4 mm.

[0054] <Manufacturing method of double-sided active metal bonding substrate> The manufacturing method of the double-sided active metal bonding substrate of the present invention includes sequentially forming a retaining wall (pattern forming process), an active metal layer (coating process, drying process), and a conductive metal layer on the ceramic substrate layer, and then performing a brazing process to complete the double-sided active metal bonding substrate.

[0055] As described above, the retaining wall, the active metal layer, and the conductive metal layer are formed on both sides of the ceramic substrate layer. In actual operation, if necessary, retaining walls can be formed on the first surface and the second surface of the ceramic substrate layer, and then the active metal layer and the conductive metal layer are sequentially provided on the first surface and the second surface. In some embodiments, the retaining wall, the active metal layer, and the conductive metal layer may be sequentially formed on the first surface of the ceramic substrate layer, and then the retaining wall, the active metal layer, and the conductive metal layer are sequentially formed on the second surface of the ceramic substrate layer.

[0056] In step S1, a patterning process for forming a retaining wall on the ceramic substrate layer is performed. The structural design of the retaining wall defines a patterned region as shown in FIG. 2.

[0057] That is, the first retaining wall is formed on the first surface of the ceramic substrate layer, and the first retaining wall defines a first patterned region. The second retaining wall is formed on the second surface of the ceramic substrate layer, and the second retaining wall defines a second patterned region. Hereinafter, for the sake of convenience of description, the manufacturing method of the double-sided active metal bonding substrate will be described from a general perspective, but the present invention is not limited thereto.

[0058] In the patterning process, the retaining wall may be formed by screen printing, but is not limited thereto.

[0059] In step S2, a preparation process for preparing an active metal solder paste is performed. The active metal solder paste is used to form the above active metal layer, and this active metal solder paste contains the above active metal solder and an organic dispersion medium.

[0060] The active metal solder contains the above-mentioned metallic silver, metallic copper, and active metal. In some embodiments, the active metal solder is a combination of metallic silver powder, metallic copper powder, and metallic titanium powder. In some 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 and an active metal powder.

[0061] When the total weight of the active metal solder is 100% by weight, the silver metal content in the active metal solder is 10 - 60% by weight, the copper metal content is 30 - 80% by weight, and the active metal content is 1 - 10% by weight.

[0062] The organic dispersion medium can assist in dispersing the active metal solder and in forming the active metal layer by shaping the active metal solder paste. Specifically, the organic dispersion medium contains a paste former, an organic solvent, and a thixotropic agent. When the total weight of the organic dispersion medium is 100% by weight, the content of the paste for paste formation is 20 - 30% by weight, the content of the organic solvent is 50 - 70% by weight, and the content of the thixotropic agent is 1 - 5% by weight. However, the present invention is not limited to this content as long as the active solder powder and the organic components can be blended into an active solder having a viscosity suitable for coating on the ceramic substrate layer to facilitate the formation of the active metal layer.

[0063] In step S3, a coating process for coating the patterned region with the active metal solder paste is performed. In the coating process, the active metal solder paste can be applied to the patterned region by screen printing.

[0064] In step S4, a drying process for forming the active metal layer from the active metal solder paste is performed. In the drying process, as shown in FIG. 3, the active metal solder paste is dried at a temperature of 90 - 110°C for 5 - 15 minutes in order to form the active metal layer by volatilizing most of the organic solvent in the active metal solder paste.

[0065] In step S5, as shown in FIG. 4, a conductive metal layer is disposed on the active metal layer.

[0066] In step S6, a soldering process for connecting the conductive metal layer to the active metal layer and fixing it to the ceramic substrate layer is performed.

[0067] In the soldering process, the first-stage heat treatment process and the second-stage heat treatment process can be sequentially performed under a vacuum degree of 8×10 -5 Torr or less. The temperature condition of the first-stage heat treatment process is 800 to 890 °C, and the temperature condition of the second-stage heat treatment program is 900 to 1100 °C (i.e., the soldering temperature range). The temperature of the second-stage heat treatment process is higher than that of the first-stage heat treatment process and is held at the maximum temperature for 30 minutes.

[0068] In a preferred embodiment, the temperature gradient (heating-up) rate of the above heat treatment process may be, for example, 5 °C / min to 30 °C / min. The cooling rate after the soldering process can be, for example, 2 °C / min to 30 °C / min.

[0069] After the conductive metal layer is provided, an etching process for removing the conductive metal layer outside the patterned area to achieve patterning and form a final product as shown in FIG. 1 can be selectively executed.

[0070] In some embodiments, during the etching process, the retaining wall may also be removed together with the conductive metal layer outside the patterned area, thereby obtaining a double-sided active metal bonding substrate as shown in FIG. 5. This step is optional and the retaining wall may not be removed.

Example

[0071] In order to verify that the double-sided active metal bonding substrate of the present invention has a high-precision patterned circuit, the double-sided active metal bonding substrates of Examples 1 to 3 and the single-sided active metal bonding substrates of Comparative Examples 1 to 3 were fabricated according to the above steps S1 to S6.

[0072] <Examples 1 to 3> In the double-sided active metal bonding substrates of Examples 1 to 3, the ceramic substrate layer is a silicon nitride ceramic substrate. The materials of the first holding wall and the second holding wall are aluminum oxide. The materials of the first active metal layer and the second active metal layer include metallic silver, metallic copper, and metallic titanium. The total weight of the active metal solder is 100% by weight, the content of metallic silver is 70% by weight, the content of metallic copper is 25% by weight, and the content of metallic titanium is 5% by weight. The first conductive metal layer and the second conductive metal layer are copper foils.

[0073] The differences among Examples 1 to 3 include that the thicknesses of the active metal layers are different, and the thickness ratios of the holding walls to the active metal layers are also different.

[0074] In the soldering process, the degree of vacuum is 8×10 -5 Torr or less, the temperature condition of the first heat treatment process is 855°C, the temperature condition of the second heat treatment process is 915°C, and it is held at the maximum temperature for 30 minutes.

[0075] After preparing the active metal bonding substrates, Table 1 shows the results of the thicknesses of the holding walls, the thicknesses of the active metal layers, the printing positions, and the presence or absence of solder diffusion after soldering in Examples 1 to 3. Also, the tensile strength of the active metal bonding substrates at a temperature of 25°C was measured according to the JIS-C-6481 standard. The results are shown in Table 1.

[0076] <Comparative Examples 1 to 3> The single-sided active metal bonding substrates of Comparative Examples 1 to 3 were fabricated using the same manufacturing method as the double-sided active metal bonding substrate of Example 1. Comparative Examples 1 to 3 have layers only on one side of the ceramic substrate layer. Also, in Comparative Examples 1 and 2, the thickness of the holding wall is greater than the thickness of the active metal layer, and in Comparative Example 3, no holding wall was provided.

[0077] After preparing the active metal bonding substrates, Table 1 shows the results of the thicknesses of the holding walls, the thicknesses of the active metal layers, the printing positions, and the presence or absence of solder diffusion after soldering in Comparative Examples 1 to 3. Also, the tensile strength of the active metal bonding substrates at a temperature of 25°C was measured according to the JIS-C-6481 standard. The results are shown in Table 1.

[0078]

Table 1

[0079] According to the results in Table 1, it can be seen that the retaining wall can prevent the diffusion of solder and maintain the miniaturization of the circuit pattern of the active metal bonding substrate. Also, when the thickness of the retaining wall is controlled to be smaller than the thickness of the active metal layer, the tensile strength of the active metal bonding substrate can be increased.

[0080] Therefore, the double-sided active metal bonding substrate of the present invention can prevent the active metal layer from overflowing from the patterned region without reducing the bonding force of the conductive metal layer (the tensile strength exceeds 100 N / cm). The double-sided printed structure of the present invention does not affect the overall structural strength, has higher functionality than the single-sided printed structure, and maintains a tensile strength exceeding 100 N / cm.

[0081] [Advantageous Effects of the Embodiment] One of the advantageous effects of the present invention is that, by means of the technical solution of "retaining wall" and "the thickness of the retaining wall is smaller than the thickness of the active metal layer", the double-sided active metal bonding substrate and its manufacturing method provided by the present invention can prevent the solder from overflowing at high temperatures, thereby improving the bonding force between the ceramic substrate layer and the conductive metal layer.

[0082] Those skilled in the art will readily understand that numerous modifications and changes may be made to the apparatus and method while maintaining the teachings of the present invention. Therefore, the above disclosure should be construed as being limited only by the boundaries of the appended claims.

Explanation of Reference Numerals

[0083] 1 Ceramic substrate layer 2 First retaining wall 2’ Second retaining wall 3 First active metal layer 3’ Second active metal layer 4 First conductive metal layer 4' Second conductive metal layer 11 First surface of ceramic substrate layer 1 11' Second surface of ceramic substrate layer 1

Claims

1. A double-sided active metal bonding substrate, comprising: a ceramic substrate layer having a first surface and a second surface; a first active metal layer disposed on the first surface; a second active metal layer disposed on the second surface; a first retaining wall surrounding and contacting the first active metal layer, wherein the thickness of the first retaining wall is smaller than the thickness of the first active metal layer; a second retaining wall surrounding and contacting the second active metal layer, wherein the thickness of the second retaining wall is smaller than the thickness of the second active metal layer; a first conductive metal layer disposed on the first active metal layer; and a second conductive metal layer disposed on the second active metal layer. A double-sided active metal bonding substrate comprising the above components.

2. The double-sided active metal bonding substrate according to Claim 1, wherein the thickness ratio of the first retaining wall to the first active metal layer is 0.10 to 0.

95.

3. The double-sided active metal bonding substrate according to Claim 1, wherein the first retaining wall comprises aluminum oxide, magnesium oxide, zirconium oxide, silicon oxide, aluminum nitride, or silicon nitride.

4. The double-sided active metal bonding substrate according to Claim 1, wherein the thickness of the first retaining wall is 1 to 5 micrometers.

5. The double-sided active metal bonding substrate according to Claim 1, wherein the width of the first retaining wall is 0.1 mm to 30 mm.

6. The double-sided active metal bonding substrate according to Claim 1, wherein the thickness of the first active metal layer is 10 to 50 micrometers.

7. A method for manufacturing a double-sided active metal bonding substrate, comprising: performing a patterning process to form a first retaining wall on a first surface of a ceramic substrate layer and a second retaining wall on a second surface of the ceramic substrate layer, wherein the first retaining wall defines a first patterned region and the second retaining wall defines a second patterned region; forming a first active metal layer in the first patterned region and a second active metal layer in the second patterned region; disposing a first conductive metal layer on the first active metal layer and a second conductive metal layer on the second active metal layer; and performing a soldering process to fix the first conductive metal layer to the ceramic substrate layer and the second active metal layer to the ceramic substrate layer. A method including that the thickness of the first holding wall is smaller than the thickness of the first active metal layer, and the thickness of the second holding wall is smaller than the thickness of the second active metal layer.

8. The method according to claim 7, wherein the sintering temperature in the brazing process is 800 to 950 °C.

9. The sintering pressure in the brazing process is less than 8 × 10 －５ Torr, the method according to claim 7.

10. The method according to claim 7, wherein the tensile strength of the double-sided active metal bonding substrate is greater than 100 N / cm.

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