Method for manufacturing ceramic substrate unit and ceramic substrate unit

Abstract

A method for manufacturing a ceramic substrate unit and a ceramic substrate unit are disclosed. The disclosed method for manufacturing a ceramic substrate unit comprises: a substrate preparation step of preparing a ceramic substrate in which a metal layer is bonded to at least one of an upper surface or a lower surface; and a part mounting step of mounting a metal part on a surface of the metal layer. The part mounting step includes: a bonding layer forming step of forming a dot bonding layer in a part mounting region on the surface of the metal layer with a paste-type filler; a part loading step of placing the metal part on the dot bonding layer on the surface of the metal layer; and a heat treatment step of bonding the metal part to the metal layer by performing heat treatment under specific conditions so that the dot bonding layer mediates bonding between the metal part and the metal layer.

Description

Method for manufacturing a ceramic substrate unit and a ceramic substrate unit

[0001] The present invention relates to a method for manufacturing a ceramic substrate unit, and more particularly to a method for manufacturing a ceramic substrate unit in which metal parts are mounted (bonded) on a metal layer of a ceramic AMB (Active Metal Brazing) substrate having metal layers attached to both sides, and to a ceramic substrate unit manufactured by the method.

[0002] Among ceramic substrates, Active Metal Brazing (AMB) substrates are primarily used in power semiconductor modules to enhance thermal management and electrical characteristics. Ceramic AMB substrates generally feature a structure containing metal conductive layers on both the top and bottom. These metal conductive layers are typically composed of copper; this structure provides high mechanical strength, thermal conductivity, and strong electrical connections, enabling the maintenance of excellent performance even in high-temperature environments.

[0003] Metal parts, such as electrical connection elements like metal pads, electrodes, and terminals, or heat dissipation elements like heatsinks, are attached to the metallized surface (top or bottom) of the ceramic AMB substrate. Various attachment methods are used during the process of bonding metal parts to the ceramic AMB substrate, and the durability and electrical and thermal performance of the bonding site are considered important factors when determining the method.

[0004] There are two main methods primarily used for mounting (bonding) metal components onto ceramic AMB substrates. The first method involves bonding metal components to the AMB substrate using paste, which cures the paste in a low-temperature environment to secure them at the bonding site. The second method utilizes brazing filler, which is melted at high temperatures and used as a bonding medium.

[0005] Metal component mounting using paste is performed at relatively low temperatures. Consequently, the thermal stress applied to the substrate during the manufacturing process is not significant. However, the paste-curing method has the disadvantage that the adhesive weakens under various external environmental conditions, such as thermal shock, peeling, pulling, or dropping, making components prone to detachment.

[0006] The brazing filler method, which uses brazing fillers, provides high bonding strength and excellent thermal and electrical conductivity. However, it is difficult to handle the filler accurately, which can lead to problems with quantity control and handling. Additionally, due to the nature of the operation being performed at high temperatures (approximately 900°C), thermal stress on the substrate increases, which may degrade its physical properties. In particular, warping or microcracks occurring at high temperatures can have a critical adverse effect on the performance or reliability of the substrate.

[0007] In the sheet method, which is primarily used for mounting small components on circuit boards among brazing filler methods, metal sheets for brazing are generally blanked to match the shape of the component to be mounted. However, there is a problem where the material loss rate increases because, depending on the shape of the component, the amount of wasted material (loss part) exceeds the amount of material actually used (use part) during the blanking process.

[0008] The sheet method also requires separate alignment loading equipment and adhesive to accurately place the punched filler sheet in the desired position, and since punches and jigs must be manufactured to fit the shape of the part, it is not suitable for multi-variety, small-batch production. In addition, in some cases, it is necessary to manufacture the sheet to be used as a brazing filler with a thickness of 30㎛ or less, but this is subject to technical and physical limitations.

[0009] Moreover, the sheet method requires complex procedures such as preparing a ceramic AMB substrate, applying a primary adhesive to the surface of the metal layer of the substrate, sheet die-cutting, placing the die-cut filler sheet, applying a secondary adhesive, placing the metal part, and brazing to mount a single metal part. Therefore, it is not efficient in terms of product mass production, and there is a problem of increased manufacturing costs due to the complex process.

[0010] The matters described in the background technology above are intended to aid in understanding the background of the invention and may include matters that are not disclosed prior art.

[0011] The technical problem that the present invention aims to solve is to provide a method for manufacturing a ceramic substrate unit and a ceramic substrate unit that can produce a more reliable product by overcoming the disadvantages of the existing paste bonding method and the brazing filler bonding method and combining the advantages of each method.

[0012] According to one aspect of the present invention as a means of solving the problem, a method for manufacturing a ceramic substrate unit is provided, comprising a substrate preparation step of preparing a ceramic substrate having a metal layer bonded to at least one of an upper surface and a lower surface, and a component mounting step of mounting a metal component on the surface of the metal layer, wherein the component mounting step comprises a bonding layer forming step of forming a dot bonding layer in a component mounting area on the surface of the metal layer with a paste-type filler, a component loading step of placing a metal component on the dot bonding layer on the surface of the metal layer, and a heat treatment step of bonding the metal component to the metal layer by performing heat treatment under specific conditions so that the dot bonding layer mediates bonding between the metal component and the metal layer.

[0013] The bonding layer forming step of the method for manufacturing a ceramic substrate unit according to one aspect of the present invention may include a first process of forming the dot bonding layer by dotting the paste-type filler onto the component mounting area using a stamping dotting method, and a second process of pre-curing the dot bonding layer by performing heat treatment under first conditions.

[0014] In a method for manufacturing a ceramic substrate unit according to one aspect of the present invention, the dot bonding layer may be composed of a plurality of dot cells in the shape of dots, the planar shape of which is one of a circle, an ellipse, or a polygon.

[0015] Here, in the first process, it is preferable to dot a paste-type filler onto the component mounting area so that adjacent dot cells are connected to each other or at least partially overlap to form the dot bonding layer in the form of a closed ring.

[0016] The paste-type filler used in the method for manufacturing a ceramic substrate unit according to one aspect of the present invention may be an Ag sintering paste in which the main component is silver (Ag) particles.

[0017] In a method for manufacturing a ceramic substrate unit according to one aspect of the present invention, the first condition for curing the dot bonding layer may be maintained in a nitrogen atmosphere and the heat treatment temperature may be 150 to 180°C.

[0018] In the substrate preparation step of the method for manufacturing a ceramic substrate unit according to one aspect of the present invention, a ceramic substrate including the metal layer can be prepared by brazing a metal foil made of one of Cu, Cu alloy, OFC, EPT Cu, and Al onto at least one of the upper and lower surfaces of a ceramic substrate.

[0019] In the bonding layer formation step of a method for manufacturing a ceramic substrate unit according to one aspect of the present invention, the dot bonding layer formed in the component mounting area is subjected to a pre-curing treatment, and in the heat treatment step, heat treatment can be performed at a temperature higher than the pre-curing treatment temperature of the dot bonding layer in the bonding layer formation step.

[0020] The heat treatment temperature in the heat treatment step of the method for manufacturing a ceramic substrate unit according to one aspect of the present invention may be 650°C or higher and 700°C or lower.

[0021] According to another aspect of the present invention as a means of solving the problem, a ceramic substrate unit is provided comprising a ceramic substrate, a metal component mounted on the ceramic substrate, and a dot bonding layer disposed between the ceramic substrate and the metal component, wherein the ceramic substrate comprises a ceramic substrate and a metal layer bonded to at least one of an upper surface and a lower surface of the ceramic substrate, and the dot bonding layer disposed in a component mounting area on the surface of the metal layer, and the dot bonding layer disposed in the component mounting area mediates the bonding between the metal layer and the metal component.

[0022] In a ceramic substrate unit according to another aspect of the present invention, the dot bonding layer can be formed by dotting a paste-type filler into the component mounting area and heat treating it.

[0023] Here, the paste-type filler forming the dot bonding layer may be an Ag sintering paste in which the main component is silver (Ag) particles.

[0024] In a ceramic substrate unit according to another aspect of the present invention, the dot bonding layer may be composed of a plurality of dot cells in the form of dots, the planar shape of which is one of a circle, an ellipse, or a polygon.

[0025] At this time, the plurality of dot cells may be connected to each other or at least partially overlap to form a single dot bonding layer. Preferably, the single dot bonding layer composed of the plurality of dot cells may be formed in a closed ring shape in which adjacent dot cells are connected to each other or at least partially overlap.

[0026] In a ceramic substrate unit according to another aspect of the present invention, the plurality of dot cells may be arranged such that a virtual cell outline connecting the outermost surfaces of the plurality of dot cells constituting a single dot junction layer is located on a virtual partition line that partitions the component mounting area.

[0027] In a ceramic substrate unit according to another aspect of the present invention, the plurality of dot cells may be arranged such that a virtual cell outline connecting the outermost surfaces of the plurality of dot cells constituting a single dot junction layer is located closer to the center of the component mounting area than a virtual partition line partitioning the component mounting area.

[0028] According to the method for manufacturing a ceramic substrate unit according to the present invention, by combining a package chip bonding process and a brazing process, the bonding between the ceramic substrate and metal parts is performed at a relatively low temperature (about 700°C) instead of the high temperature (about 900°C) required in conventional brazing methods, thereby significantly reducing thermal shock of the substrate and the resulting damage.

[0029] In addition, by performing the bonding between the substrate and the metal component at a relatively lower temperature compared to conventional brazing methods to reduce thermal shock to the substrate, and by performing the operation (bonding or joining the metal component to a designated area of ​​the metal layer of the ceramic substrate) at a temperature (approximately 700°C range) where electrical characteristics can be maximized by strengthening the bonding between the particles (Ag particles) constituting the filler, the quality and reliability of the product can be significantly improved.

[0030] In addition, a paste-type filler is used as a filler to mediate the bonding between the ceramic substrate and the metal component, and by forming a bonding layer (dot bonding layer) with small dots through a stamping method, the shape of the bonding layer can be varied according to the metal component to be bonded, thereby increasing process flexibility. Furthermore, since the metal component can be temporarily fixed on the substrate by using a paste-type filler, the use of a separate adhesive can be eliminated.

[0031] In addition, by applying a method of forming a bonding layer through a stamping process, filler loss is significantly reduced compared to the conventional method using sheet-type brazing fillers, separate stamping equipment is not required, and the manufacturing process can be simplified and manufacturing costs reduced compared to the conventional method using sheet-type brazing fillers by omitting stamping processes and adhesive application processes.

[0032] FIG. 1 is a flowchart illustrating a method for manufacturing a ceramic substrate unit according to an embodiment of the present invention.

[0033] FIG. 2 is a schematic diagram of a process for manufacturing a ceramic substrate unit according to an embodiment of the present invention.

[0034] FIG. 3 is a drawing illustrating a preferred embodiment of a dot bonding layer.

[0035] FIG. 4 is a schematic cross-sectional view of a ceramic substrate unit manufactured by the method for manufacturing a ceramic substrate unit according to the present invention.

[0036] FIG. 5 is an enlarged view of the essential part of the present invention, showing part 'A' of FIG. 4 in enlarged form.

[0037] Figure 6 is a drawing illustrating a preferred arrangement of dot bonding layers applied to a ceramic substrate unit.

[0038] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0039] In describing the embodiments of the present invention, identical or similar components are assigned the same reference numerals, and redundant descriptions thereof are omitted. Furthermore, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions could obscure the essence of the embodiments disclosed in this specification.

[0040] In addition, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings, and it should be noted that they include all modifications, equivalents, and substitutions that fall within the concept and technical scope of the present invention.

[0041] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0042] Furthermore, when it is mentioned that a component is "connected" or "joined" to another component, it should be understood that while it may be directly connected or joined to that other component, there may also be other components in between.

[0043] On the other hand, when it is stated that one component is "directly connected" or "directly coupled" to another component, it should be understood that there are no other components in between.

[0044] Furthermore, terms such as "comprising," "having," and "having" used in describing embodiments of the present invention are intended to specify the existence of features, numbers, steps, actions, components, parts, or combinations thereof of the invention, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0045] And the fact that one component is in the "front," "rear," "upper," or "lower" of another component includes, unless there are special circumstances, not only being placed in the "front," "rear," "upper," or "lower" of the other component in direct contact with it, but also having another component placed in between.

[0046] The drawings are intended solely to facilitate an understanding of the concept of the present invention and should not be interpreted as limiting the scope of the invention. Furthermore, it is noted that relative thicknesses, lengths, or sizes in the drawings may be exaggerated for convenience and clarity of explanation.

[0047] FIG. 1 is a flowchart for explaining a method for manufacturing a ceramic substrate unit according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a process for manufacturing a ceramic substrate unit according to an embodiment of the present invention.

[0048] Referring to FIGS. 1 and 2, a manufacturing method according to an embodiment includes a substrate preparation step (S100) for preparing a ceramic substrate (10) and a component mounting step (S200) for mounting metal parts (30) on the ceramic substrate (10) through a series of processes. In the substrate preparation step (S100), a ceramic substrate (10) is prepared in which a metal layer (14) is bonded to at least one of the upper and lower surfaces of a ceramic substrate (12), and in the component mounting step (S200), the metal parts (30) can be mounted on the surface of the metal layer (14).

[0049] For reference, the metal parts (30) mounted on the metalized surface (metal layer surface) of the ceramic substrate (10) in the component mounting step (S200) include electrical connection elements such as metal pads, electrodes, and terminals, or heat dissipation elements such as heat sinks.

[0050] In the substrate preparation step (S100), a ceramic substrate (10) can be prepared in which a metal layer (14) is formed on at least one of the upper and lower surfaces of the ceramic substrate (12) by brazing a conductive metal foil onto at least one of the upper and lower surfaces of the ceramic substrate (12). In the substrate preparation step (S100), the ceramic substrate (12) may be any one of alumina (Al2O3), AlN, SiN, Si3N4, and ZTA (Zirconia Toughened Alumina), but is not limited thereto.

[0051] As mentioned, the metal layer (14) bonded to at least one of the upper and lower surfaces of the ceramic substrate (12) in the substrate preparation step (S100) can be formed by brazing a conductive metal foil to the surface of the ceramic substrate (12). The metal layer (14) can be formed into a predetermined electrode pattern suitable for mounting a metal component (30) through an additional etching process, and may be a material having high heat dissipation and conductivity such as Cu, Cu alloy (CuMo, etc.), OFC, EPT Cu, Al, etc.

[0052] In the manufacturing method according to the embodiment, the component mounting step (S200) may consist of a bonding layer forming step (S202), a component loading step (S204), and a heat treatment step (S206). The bonding layer forming step (S202) is a step of forming a dot bonding layer (20, a bonding layer composed of small dots) in a planned component mounting area on the surface of the metal layer (14) using a paste-type filler, and in the component loading step (S204), the operation of accurately placing a metal component (30) on the dot bonding layer (20) may be performed.

[0053] In the bonding layer formation step (S202), a stamping dotting method may be applied. In the bonding layer formation step (S202), a dot bonding layer (20) consisting of a plurality of small dots can be formed in the component mounting area through the stamping dotting method. For reference, the stamping dotting method refers to a filler application method in which a small amount of filler in the form of paste is precisely applied to a planned location as if stamping a dot.

[0054] The bonding layer forming step (S202) applied to the method for manufacturing a ceramic substrate unit (1) according to an embodiment may be composed of a first process and a second process. In the first process, a process is performed to form a dot bonding layer (20) by dotting a paste-type filler onto a planned component mounting area using dedicated stamping dotting equipment, and in the second process, a process of pre-curing the dot bonding layer (20) through heat treatment may be performed.

[0055] In the method for manufacturing a ceramic substrate unit (1) according to an embodiment, the dot bonding layer (20) may be composed of a plurality of dot cells (22) in the shape of a dot, the planar shape of which is one of a circle, an ellipse, or a polygon. In the first process of forming the dot bonding layer (20), as shown in the example of FIG. 3, a paste-type filler may be dotted onto a component mounting area so that the dot cells (22) are connected to each other or at least partially overlap each other to form a closed ring-shaped dot bonding layer (20).

[0056] When the dot bonding layer (20) is formed in a closed ring shape, heat generated from the metal part (30) is dispersed and transferred to the metal layer (14), thereby preventing overheating of the metal part (30), and electrically, current can be transmitted between adjacent dot cells (22), thereby improving conductivity. The closed ring shape is also a very efficient filler arrangement shape that can prevent unnecessary overuse of filler due to the hollow region (empty space) formed in the center, while ensuring sufficient bonding force between bonding targets.

[0057] Although the drawing (Fig. 3) illustrates a configuration in which the dot bonding layer (20) is formed in a circular ring shape (annular), the shape of the dot bonding layer (20) is not limited to a circular ring shape. It should be noted that, depending on the external shape of the metal part (30) (more precisely, the shape of the bottom surface of the metal part), it can be formed in an elliptical or triangular or polygonal ring shape, and such variations may also be included within the scope of the present invention.

[0058] Even when forming a dot bonding layer (20) in the form of a closed ring, it is preferable to arrange the dot cells (22) such that a virtual outline (L1) connecting the outermost edges of the dot cells (22) coincides with a virtual partition line (L2, see FIG. 6) that partitions the component mounting area, or is positioned closer to the center of the component mounting area. This is because if the filler deviates from the planned component mounting area, it may have an adverse effect on the performance or quality of the product.

[0059] The paste-type filler forming the dot bonding layer (20) in the first process may be an Ag sintering paste whose main component is silver (Ag) particles. The Ag sintering paste maintains the high thermal conductivity of silver and has the characteristic of efficiently dispersing heat at the bonding area to prevent overheating of the semiconductor component. This characteristic is particularly advantageous for components that generate high heat, such as power devices.

[0060] Ag sintered paste also bonds well with copper (Cu) electrodes to maintain low electrical resistance and can increase power efficiency with high electrical conductivity, and can reduce thermal damage to ceramic substrates because sintering is possible in a low-temperature environment of less than 200°C. Therefore, it is advantageous for increasing the durability of semiconductors and substrates compared to conventional brazing, which requires operation at high temperatures.

[0061] Ag sintering paste can be prepared by mixing an organic binder, a solvent, a sintering accelerator, and additives in specific proportions with silver (Ag) particles, which are the main component. If necessary, an adhesion accelerator may be added. Here, the adhesion accelerator is intended to enhance adhesion with copper, and examples include silane coupling agents, titanate coupling agents, and phosphate esters.

[0062] For reference, in Ag sintered paste, silver particles serve as the basic conductive component, providing high thermal and electrical conductivity and playing a crucial role in heat dissipation and power transfer. Additionally, the binder controls the viscosity and stability of the paste and helps maintain it well once applied to the substrate, while the solvent regulates viscosity to ensure the paste is applied smoothly and evaporates during the heating process.

[0063] Sintering accelerators play a role in lowering the sintering temperature, enabling silver particles to bond at a relatively low temperature (about 200°C or lower), and decompose when heat is applied to help bond between the silver particles. Additionally, additives ensure that silver particles are uniformly distributed to prevent aggregation and maintain uniform conductivity and adhesion; surfactants or dispersants may be used as additives.

[0064] In the bonding layer formation step (S202), the paste-type filler forming the dot bonding layer (20) is preferably the aforementioned Ag sintered paste, but is not limited thereto. In some cases, solder or epoxy may be used as the paste-type filler forming the dot bonding layer (20).

[0065] In the second process included in the bonding layer formation step (S202), a treatment is performed to pre-cur the dot bonding layer (20) formed on the surface of the metal layer (14) through the aforementioned first process. In the second process, the dot bonding layer (20) can be pre-cured by performing heat treatment under the first condition. In the embodiment, the first condition (heat treatment condition) for pre-curing the dot bonding layer (20) may be a condition in which the heat treatment temperature is maintained in a nitrogen atmosphere and the heat treatment temperature is 150 to 180°C.

[0066] Although silver (Ag) can easily oxidize during the heat treatment process, the nitrogen atmosphere maintains an inert state, thereby suppressing oxidation and maintaining the purity of the dot bonding layer (20), which can improve the electrical properties and durability of the dot bonding layer (20). Also, a temperature range of 150 to 180°C is suitable for pre-curing while stably maintaining the properties (conductivity and bonding properties) of silver.

[0067] If pre-curing is performed at a temperature much lower than the melting point of silver (961.8°C), mechanical strength can be secured while minimizing structural deformation or unnecessary material changes of the dot bonding layer (20) due to fine curing. In addition, curing at a low temperature is advantageous for maintaining the uniformity of the silver-based dot bonding layer (20) and can make the bonding layer more robust, thereby improving adhesion with the metal layer (14). This can contribute to increasing the reliability of the entire bonding structure.

[0068] In addition, since the temperature range of 50 to 180°C consumes less energy, process costs can be significantly reduced compared to heat treatment at high temperatures.

[0069] The heat treatment step (S206), which is the final step in the component mounting step (S200) included in the method for manufacturing a ceramic substrate unit (1) according to the embodiment, is a step of bonding a metal component (30) to a metal layer (14) through final heat treatment. In the heat treatment step (S206), a process of bonding a metal component (30) to a metal layer (14) can be performed by performing heat treatment under specific conditions so that the previously formed dot bonding layer (20) mediates bonding between the metal component (30) loaded thereon through the component loading step (S204) and the metal layer (14).

[0070] In the heat treatment step (S206), heat treatment is performed at a temperature higher than the heat treatment temperature for pre-curing the dot bonding layer (20) in the bonding layer formation step (S202). The heat treatment temperature in the heat treatment step (S206) may be 650°C or higher and 700°C or lower. At a temperature of 650°C to 700°C, which is lower than the melting point of silver (961.8°C), the bonding layer can be firmly fixed while preventing the silver particles from diffusing excessively into each other.

[0071] In other words, if the final heat treatment is performed at a temperature of 650°C to 700°C, which is lower than the melting point of silver (961.8°C), it is possible to provide sufficient energy to strengthen the bond between the silver dot bonding layer (20) and the metal part (30), while minimizing structural instability or deformation caused by excessive diffusion of silver particles.

[0072] In addition, since the heat treatment temperature of 650°C to 700°C is a temperature at which the silver is not melted while maintaining sufficient fluidity, the bonding between the dot bonding layer (20) and the metal layer (14) can be optimized, and physical deformation or overheating of the metal part (30) due to excessive heat can be prevented.

[0073] In addition, at high temperatures close to 961.8°C, the difference in thermal expansion between the substrate and the metal part (30) increases, causing thermal stress in the bonding layer, which may result in structural cracks or damage. However, 650°C to 700°C can provide sufficient temperature necessary for bonding while relieving such thermal stress, and heat treatment at a temperature much lower than the melting point can maintain the conductive properties of silver, thereby optimizing the conductivity of the bonding layer and improving overall electrical performance.

[0074] As described above, the method for manufacturing a ceramic substrate unit according to the embodiment is a method that combines a package chip bonding process and a brazing process. In the bonding between the ceramic substrate and metal parts, the bonding is performed at a relatively low temperature (about 700°C) instead of the high temperature (about 900°C) required in conventional brazing methods, thereby significantly reducing thermal shock of the substrate and the resulting damage.

[0075] In addition, by performing the bonding between the substrate and the metal component at a relatively lower temperature compared to conventional brazing methods to reduce thermal shock to the substrate, and by performing the operation (bonding or joining the metal component to a designated area of ​​the metal layer of the ceramic substrate) at a temperature (approximately 700°C range) where electrical characteristics can be maximized by strengthening the bonding between the particles (Ag particles) constituting the filler, the quality and reliability of the product can be significantly improved.

[0076] In addition, a paste-type filler is used as a filler to mediate the bonding between the ceramic substrate and the metal component, and by forming a bonding layer (dot bonding layer) with small dots through a stamping method, the shape of the bonding layer can be varied according to the metal component to be bonded, thereby increasing process flexibility. Furthermore, since the metal component can be temporarily fixed on the substrate by using a paste-type filler, the use of a separate adhesive can be eliminated.

[0077] In addition, by applying a method of forming a bonding layer through a stamping process, filler loss is significantly reduced compared to the conventional method using sheet-type brazing fillers, separate stamping equipment is not required, and the manufacturing process can be simplified and manufacturing costs reduced compared to the conventional method using sheet-type brazing fillers by omitting stamping processes and adhesive application processes.

[0078] Next, we will examine the ceramic substrate unit (1) manufactured by the manufacturing method of the ceramic substrate unit described above with reference to the drawings.

[0079] FIG. 4 is a schematic cross-sectional view of a ceramic substrate unit manufactured by the method for manufacturing a ceramic substrate unit described above, and FIG. 5 is an enlarged view of the main part of the ceramic substrate unit shown in FIG. 4, and is an enlarged view of the main part of the present invention showing part 'A' of FIG. 4.

[0080] Referring to FIGS. 4 and 5, a ceramic substrate unit (1) according to an embodiment comprises a ceramic substrate (10), a metal component (30) mounted on the ceramic substrate (10), and a dot bonding layer (20) disposed between the ceramic substrate (10) and the metal component (30). The ceramic substrate (10) may be an Active Metal Brazing (AMB) substrate comprising a ceramic substrate (12) and a metal layer (14) bonded to the surface of the ceramic substrate (12) (at least one of the upper and lower surfaces), but is not limited thereto.

[0081] The ceramic substrate (12) constituting the ceramic substrate (10) may be composed of one of the following materials: alumina (Al2O3), AlN, SiN, Si3N4, and the metal layer (14) may be formed by brazing a conductive metal foil onto the surface of the ceramic substrate (12). The metal layer (14) may be formed into a predetermined electrode pattern suitable for mounting a metal component (30) through an additional etching process and may be made of a metal material having high heat dissipation and conductivity, such as Cu, Cu alloy, OFC, EPT Cu, Al, etc.

[0082] The ceramic substrate (10) applied to the ceramic substrate unit (1) according to the embodiment is not limited to an AMB (Active Metal Brazing) substrate in which a metal layer (14) is bonded to the surface (at least one of the upper and lower surfaces) of a ceramic substrate (12). Depending on the application environment or product, the ceramic substrate (10) may be a DBC (Direct Bonding Copper) substrate, a TPC (Thick Printing Copper) substrate, or a DBA (Direct Brazed Aluminum) substrate.

[0083] A dot bonding layer (20) may be disposed on the surface of a metal layer (14) of a ceramic substrate (10). The dot bonding layer (20) may be disposed in a designated component mounting area (a pre-planned component mounting area) on the surface of the metal layer (14). The dot bonding layer (20) disposed in the component mounting area mediates a stable bonding (or connection) between the metal layer (14) and the metal component (30). The drawing illustrates a metal component (30) mounted on the surface of the upper metal layer (14), but is not limited thereto.

[0084] In the embodiment, the metal parts (30) mounted on the metalized surface (metal layer surface) of the ceramic substrate (10) may be electrical connection elements such as metal pads, electrodes, and terminals. In the embodiment, the metal parts (30) mounted on the metalized surface of the ceramic substrate (10) may be heat dissipation elements such as heat sinks. Of course, in addition to the parts mentioned, any metal element that can be mounted on the substrate may be.

[0085] In the ceramic substrate unit (1) according to the embodiment, the dot bonding layer (20) can be formed by dotting a paste-type filler into the component mounting area through stamping dotting and heat treating. Here, stamping dotting refers to a filler application method in which a small amount of paste-type filler is precisely applied to a planned location as if making a dot.

[0086] In the ceramic substrate unit (1) according to the embodiment, the dot bonding layer (20) may be composed of dot cells (22) in the shape of a dot, the planar shape of which is one of a circle, an ellipse, or a polygon. The dot cells (22) may be connected to each other or at least partially overlap each other to form a single dot bonding layer (20). Preferably, a single dot bonding layer (20) may be formed in the shape of a closed ring in which adjacent dot cells (22) are connected to each other or at least partially overlap each other (see FIG. 3).

[0087] When the dot bonding layer (20) is formed in a closed ring shape, heat generated from the metal part (30) is dispersed and transferred to the metal layer (14), so overheating is effectively prevented, and in terms of electricity, current flow between adjacent dot cells (22) is possible, thereby improving conductivity. In addition, the closed ring shape is a very efficient filler arrangement shape that can prevent unnecessary overuse of filler due to the hollow region (empty space) formed in the center while ensuring sufficient bonding strength.

[0088] Even when forming the dot bonding layer (20) in the form of a closed ring, as shown in the example of FIG. 6, it is preferable to form the dot cells (22) such that the virtual outline (L1) connecting the outermost edges of the dot cells (22) coincides with the virtual partition line (L2) that partitions the component mounting area, or is located closer to the center of the component mounting area. This is because if the filler deviates from the planned component mounting area, it may have an adverse effect on the performance or quality of the product.

[0089] The paste-type filler forming the dot bonding layer (20) may be an Ag sintering paste in which the main component is silver (Ag) particles. The Ag sintering paste maintains the high thermal conductivity of silver and has the characteristic of efficiently dispersing heat at the bonding area to prevent overheating of the semiconductor component. This characteristic is particularly advantageous for components that generate high temperatures, such as power devices.

[0090] Ag sintered paste also bonds well with copper (Cu) electrodes to maintain low electrical resistance and can increase power efficiency with high electrical conductivity, and can reduce thermal damage to ceramic substrates because sintering is possible in a low-temperature environment of less than 200°C. Therefore, it is advantageous for increasing the durability of semiconductors and substrates compared to conventional brazing, which requires operation at high temperatures.

[0091] Ag sintering paste can be prepared by mixing an organic binder, a solvent, a sintering accelerator, and additives in specific proportions with silver (Ag) particles, which are the main component. If necessary, an adhesion accelerator may be added. Here, the adhesion accelerator is intended to enhance adhesion with copper, and examples include silane coupling agents, titanate coupling agents, and phosphate esters.

[0092] For reference, in Ag sintered paste, silver particles serve as the basic conductive component, providing high thermal and electrical conductivity and playing a crucial role in heat dissipation and power transfer. Additionally, the binder controls the viscosity and stability of the paste and helps maintain it well once applied to the substrate, while the solvent regulates viscosity to ensure the paste is applied smoothly and evaporates during the heating process.

[0093] Sintering accelerators play a role in lowering the sintering temperature, enabling silver particles to bond at a relatively low temperature (about 200°C or lower), and decompose when heat is applied to help bond between the silver particles. Additionally, additives ensure that silver particles are uniformly distributed to prevent aggregation and maintain uniform conductivity and adhesion; surfactants or dispersants may be used as additives.

[0094] As mentioned, the dot bonding layer (20) can be formed by dotting a paste-type filler through stamping dotting and then heat-treating and curing it. The treatment conditions (heat treatment conditions) for the pre-curing of the dot bonding layer may be conditions maintained in a nitrogen atmosphere and a heat treatment temperature of 150 to 180°C.

[0095] Although silver (Ag) can easily oxidize during the heat treatment process, the nitrogen atmosphere maintains an inert state, thereby suppressing oxidation and maintaining the purity of the dot bonding layer (20), which can improve the electrical properties and durability of the dot bonding layer (20). Also, a temperature range of 150 to 180°C is suitable for pre-curing while stably maintaining the properties (conductivity and bonding properties) of silver.

[0096] If pre-curing is performed at a temperature much lower than the melting point of silver (961.8°C), mechanical strength can be secured while minimizing structural deformation or unnecessary material changes of the dot bonding layer (20) due to fine curing. In addition, curing at a low temperature is advantageous for maintaining the uniformity of the silver-based dot bonding layer (20) and can make the bonding layer more robust, thereby improving adhesion with the metal layer (14).

[0097] Meanwhile, the ceramic substrate unit (1) according to the embodiment can be manufactured by placing a metal part (30) on a dot bonding layer (20) and performing a final heat treatment at a predetermined temperature. In the final heat treatment step (S206), the heat treatment can be performed at a temperature higher than the temperature at which the dot bonding layer (20) is cured, so that the dot bonding layer (20) mediates a stable and robust bond between the metal part (30) placed thereon and the metal layer (14).

[0098] The heat treatment temperature may preferably be 650°C or higher and 700°C or lower. A temperature of 650°C to 700°C, which is lower than the melting point of silver (961.8°C), provides sufficient energy to strengthen the bond between the silver dot bonding layer (20) and the metal part (30), while preventing excessive diffusion of silver particles, thereby minimizing structural instability or deformation and firmly fixing the dot bonding layer (20).

[0099] The heat treatment temperature of 650℃ to 700℃ is also a temperature at which the silver is not melted but can maintain sufficient fluidity, so that an optimized bond between the dot bonding layer (20) and the metal layer (14) can be achieved, and physical deformation or overheating of the metal part (30) due to excessive heat can be prevented.

[0100] In addition, at high temperatures close to 961.8°C, the difference in thermal expansion between the substrate and the metal part (30) increases, causing thermal stress in the bonding layer, which may result in structural cracks or damage. However, 650°C to 700°C can provide sufficient temperature necessary for bonding while relieving such thermal stress, and heat treatment at a temperature much lower than the melting point can maintain the conductive properties of silver, thereby optimizing the conductivity of the bonding layer and improving overall electrical performance.

[0101] The ceramic substrate unit according to the above embodiment can be applied to a power module to secure both multiple connections of semiconductor chips and heat dissipation effects, and since it also contributes to miniaturization, the quality and performance of the power module can be significantly improved. Of course, the ceramic substrate unit according to the embodiment can be applied to various module components used for high power in addition to the aforementioned power module.

[0102] The above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention.

[0103] Accordingly, the embodiments disclosed in this invention are intended to illustrate, not limit, the technical concept of the invention, and the scope of the technical concept of the invention is not limited by these embodiments. The scope of protection of this invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of this invention.

[0104] The above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention.

[0105] Accordingly, the embodiments disclosed in this invention are intended to illustrate, not limit, the technical concept of the invention, and the scope of the technical concept of the invention is not limited by these embodiments. The scope of protection of this invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of this invention.

Claims

1. A substrate preparation step of preparing a ceramic substrate having a metal layer bonded to at least one of an upper surface and a lower surface; and A component mounting step of mounting a metal component on the surface of the metal layer; is included, The above component mounting step is, A bonding layer forming step of forming a dot bonding layer in a component mounting area on the surface of the metal layer using a paste-type filler, and A part loading step of placing a metal part on the dot bonding layer on the surface of the metal layer, and A method for manufacturing a ceramic substrate unit, comprising: a heat treatment step of bonding a metal part to a metal layer by performing heat treatment such that the dot bonding layer mediates bonding between the metal part and the metal layer.

2. In Paragraph 1, The above dot bonding layer is, A method for manufacturing a ceramic substrate unit composed of multiple dot cells in the shape of dots, the planar shape of which is one of a circle, an ellipse, or a polygon.

3. In Paragraph 2, A method for manufacturing a ceramic substrate unit, wherein the dot bonding layer is formed in a closed ring shape in which at least a portion of adjacent dot cells overlap.

4. In Paragraph 1, The above bonding layer formation step is, A first process of forming a dot bonding layer by dotting the paste-type filler into the component mounting area, and A method for manufacturing a ceramic substrate unit, comprising a second process of pre-curing the dot bonding layer by performing heat treatment under a first condition.

5. In Paragraph 4, The above paste-type filler is, A method for manufacturing a ceramic substrate unit, wherein the main component is an Ag sintering paste having silver (Ag) particles.

6. In Paragraph 4, The first condition for the curing of the dot bonding layer is, A method for manufacturing a ceramic substrate unit, maintained in a nitrogen atmosphere and having a heat treatment temperature of 150 to 180°C.

7. In Paragraph 1, In the above substrate preparation step, A method for manufacturing a ceramic substrate unit, wherein a metal foil composed of one of Cu, Cu alloy, OFC, EPT Cu, and Al is brazed to at least one of the upper and lower surfaces of a ceramic substrate to prepare a ceramic substrate comprising said metal layer.

8. In Paragraph 1, In the above bonding layer formation step, the dot bonding layer formed in the component mounting area is subjected to pre-curing treatment, and A method for manufacturing a ceramic substrate unit, wherein in the above heat treatment step, heat treatment is performed at a temperature higher than the pre-curing treatment temperature of the dot bonding layer in the above bonding layer formation step.

9. In Paragraph 8, The above paste-type filler is an Ag sintering paste whose main component is silver (Ag) particles, and The heat treatment temperature for the pre-curing of the above dot bonding layer is 150°C or higher and 180°C or lower, and A method for manufacturing a ceramic substrate unit, wherein the heat treatment temperature in the above heat treatment step is 650°C or higher and 700°C or lower.

10. Ceramic substrate; A metal component mounted on the ceramic substrate; and It includes a dot bonding layer disposed between the ceramic substrate and the metal component; and The ceramic substrate comprises a ceramic base and a metal layer bonded to at least one of the upper and lower surfaces of the ceramic base, and The dot bonding layer is disposed in the component mounting area on the surface of the metal layer, and A ceramic substrate unit in which the dot bonding layer disposed in the component mounting area mediates the bonding between the metal layer and the metal component.

11. In Paragraph 10, A ceramic substrate unit in which the above dot bonding layer is formed by dotting a paste-type filler into the component mounting area and heat treating it.

12. In Paragraph 11, A ceramic substrate unit in which the paste-type filler forming the dot bonding layer is an Ag sintering paste whose main component is silver (Ag) particles.

13. In Paragraph 10, The above dot bonding layer is, A ceramic substrate unit composed of multiple dot cells in the shape of dots, the planar shape of which is one of a circle, ellipse, or polygon.

14. In Paragraph 13, The above dot bonding layer is formed in the shape of a closed ring, and A ceramic substrate unit in which a plurality of dot cells forming a closed ring-shaped dot junction layer overlap at least partially with neighboring ones.

15. In Paragraph 13, A ceramic substrate unit in which a plurality of dot cells are arranged such that a virtual cell outline connecting the outermost surfaces of the plurality of dot cells constituting a single dot bonding layer is positioned on a virtual partition line that partitions the component mounting area.

16. In Paragraph 13, A ceramic substrate unit in which a plurality of dot cells are arranged such that a virtual cell outline connecting the outermost surfaces of the plurality of dot cells constituting a single dot bonding layer is positioned closer to the center of the component mounting area than a virtual partition line partitioning the component mounting area.

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