Method for manufacturing a printed circuit board

Abstract

The present application relates to a method of manufacturing a printed circuit board. According to the present application, a printed circuit board having excellent bonding force between a ceramic substrate and a metal sheet can be manufactured, and manufacturing cost thereof can be reduced.

Description

Technical Field

[0001] This application relates to a method for manufacturing printed circuit boards. More specifically, this application relates to a method for manufacturing printed circuit boards that can reduce production costs and improve the bonding strength between the layers forming the board. Background Technology

[0002] Driven by the trends towards miniaturization, lighter weight, and higher functionality in electronic devices, the application areas of multilayer printed circuit boards (PCBs) have expanded to include smaller devices. Consequently, the demand for multilayer PCBs is increasing.

[0003] Boards used for multilayer printed circuits can range from flat wiring to three-dimensional wiring. Especially in the field of industrial electronics, they improve the integration of functional components (e.g., ICs (integrated circuits) or LSIs (large-scale integration, etc.)). Multilayer printed circuit boards are also beneficial for miniaturization, light weight, high functionality, structural and electrical integration of electronic devices, reduced assembly time and lower costs.

[0004] A substrate for printed circuits can be manufactured by bonding a metal sheet, such as a copper sheet, to opposite sides of a ceramic substrate formed of aluminum oxide (Al2O3), aluminum nitride (AlN), or silicon nitride (Si3N4).

[0005] Bonding methods used for printed circuit boards can be mainly classified into the following three types: active metal brazing (AMB) using a paste mainly composed of Ag, direct bonding using an oxide layer on a ceramic substrate, and diffusion bonding using metal deposition and diffusion reactions.

[0006] Among these methods, the active metal bonding method suffers from the problem of Ag diffusing to the edges during power semiconductor module operation, while the direct bonding method suffers from the problem of reduced thermal conductivity due to the oxide layer. On the other hand, the diffusion bonding method can form a thin deposition layer with a thickness of several hundred nanometers through solid-state reaction, thus requiring a much smaller amount of metal, such as Ag, compared to the active metal bonding method. Furthermore, due to its excellent bonding strength, it has the following advantages: it can manufacture printed circuit boards with excellent thermal shock properties.

[0007] On the other hand, printed circuit boards are repeatedly exposed to heat through the application of voltage or subjected to thermal shock conditions due to changes in the surrounding environment. At this time, thermal stress is generated due to the difference in thermal expansion coefficients between the ceramic substrate and the metal sheet (e.g., copper sheet), and peeling may occur due to repeated thermal shocks.

[0008] Therefore, there is a need for a technology to manufacture printed circuit boards with strong interlayer bonding strength while reducing production costs. Summary of the Invention

[0009] Technical issues

[0010] One object of the present invention is to provide a method for manufacturing printed circuit boards that can reduce production costs.

[0011] Another object of the present invention is to provide a printed circuit board with strong interlayer bonding strength, so that it will not peel off even under thermal shock conditions.

[0012] The above and other objectives of this application can be achieved by the following detailed description of this application.

[0013] Technical solution

[0014] To achieve the above objectives, in one aspect, a method for manufacturing a printed circuit board includes: a first step, wherein an upper surface and a lower surface facing each other are prepared with an area of ​​S. A A ceramic substrate (A) having an area of ​​S. A A deposition layer is formed on the upper and lower surfaces of the substrate, and a ceramic substrate (A) is fabricated on the upper and lower surfaces facing each other, respectively forming an upper deposition layer and a lower deposition layer; in the second step, an upper metal sheet (B) and a lower metal sheet (B') are prepared, the upper metal sheet (B) and the lower metal sheet (B') having an area of ​​S. B A surface with area S B It is the area S A More than 1.5 times; the third step, wherein the metal sheet (B, B') and two or more ceramic substrates (A) are arranged such that the two or more ceramic substrates (A) are positioned side by side facing each other on the upper metal sheet (B) with an area of ​​S. B The area of ​​the aforementioned surface and the lower metal sheet (B') is S. B In the plane between the two surfaces; and in the fourth step, hot-pressing the upper metal sheet (B) and the lower metal sheet (B') to bond the metal sheets (B, B') to the ceramic substrate (A) through the upper deposition layer and the lower deposition layer.

[0015] Beneficial effects

[0016] According to this application, printed circuit boards with excellent bonding strength between ceramic substrates and metal sheets can be manufactured, and their manufacturing costs can be reduced. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view of the ceramic substrate 100, deposited layer 200 and metal sheet 300 relative to the manufacturing process of a printed circuit board according to an embodiment of this application.

[0018] Figure 2The arrangement of the metal sheet and ceramic substrate in the related technology and this application is illustrated schematically.

[0019] Figure 3 This is a cross-sectional view of a printed circuit board including a ceramic substrate 100, a bonding layer 200a, and a metal sheet 300 according to an embodiment of this application.

[0020] Figure 4 These are scanning electron microscope (SEM) images of cross-sections of a ceramic substrate and a deposited layer formed according to embodiments of this application.

[0021] Figure 5 These are scanning electron microscope (SEM) images of cross sections of a ceramic substrate, bonding layer, and metal sheet formed according to embodiments of this application. Detailed Implementation

[0022] The present application will now be described in detail with reference to the accompanying drawings of specific embodiments thereof.

[0023] For clarity, parts irrelevant to the description have been omitted from the drawings, and the same or similar reference numerals are used for the same elements throughout the specification. Furthermore, since the dimensions and thicknesses of each element shown in the drawings have been arbitrarily exaggerated or reduced for ease of description, the dimensions and thicknesses of the elements in this application are not necessarily limited to those shown.

[0024] In this specification, the term "above" is used in relation to the position between elements to correspond to the meaning of "above" or "on top," and unless otherwise stated, an element having a corresponding position is in direct contact with another element, which may indicate a situation where it is above the other element, or it may indicate a situation where another element is present between them.

[0025] In this specification, unless otherwise defined, "area" means the area of ​​each element visible when viewed from the top or bottom in a direction parallel to the normal direction of the surface, such as projected area.

[0026] Throughout this specification, the terms “comprising” or “having” mean that other elements may be further included unless otherwise stated.

[0027] In this specification, the terms "step" and "process" are used interchangeably with the same meaning.

[0028] In embodiments relating to this application, the application relates to a method for manufacturing a substrate for printed circuits. This method can be performed by manufacturing a laminate containing predetermined elements and hot-pressing the laminate.

[0029] For example, such as Figure 1As shown, the manufacturing method can be performed as follows. First, a ceramic substrate 100 is prepared, and a deposition layer 200 is formed on two opposing surfaces of the ceramic substrate 100. After placing a metal sheet 300 on the deposition layer 200, the ceramic substrate 100 and the metal sheet 300 are bonded together by hot pressing the metal sheet outside the ceramic substrate.

[0030] According to specific embodiments of the manufacturing process involved in this application, the area of ​​the ceramic substrate and the metal sheet and / or their stacking position before bonding can be adjusted, thereby reducing production costs. Furthermore, according to specific embodiments of this application, excellent adhesion between the ceramic substrate and the metal sheet can be provided by adjusting the deposition elements and their content.

[0031] Specifically, a method for manufacturing a printed circuit board includes:

[0032] The first step involves preparing the area of ​​the upper surface and the area of ​​the lower surface facing each other, which are S. A A ceramic substrate (A) having an area of ​​S. A A deposition layer is formed on the upper surface and the lower surface, and a ceramic substrate (A) is manufactured with an upper deposition layer and a lower deposition layer formed on the upper surface and the lower surface facing each other, respectively.

[0033] The second step involves preparing an upper metal sheet (B) and a lower metal sheet (B'), wherein the upper metal sheet (B) and the lower metal sheet (B') have an area of ​​S. B A surface with area S B It is the area S A More than 1.5 times;

[0034] In the third step, the metal sheet (B, B') and two or more ceramic substrates (A) are arranged such that the two or more ceramic substrates (A) are positioned side by side on the upper metal sheet (B) facing each other, with an area of ​​S. B The area of ​​the aforementioned surface and the lower metal sheet (B') is S. B In the plane between the said one surfaces; and

[0035] The fourth step involves hot-pressing the upper metal sheet (B) and the lower metal sheet (B') to bond the metal sheets (B, B') to the ceramic substrate (A) through the upper and lower deposition layers.

[0036] The following sections will describe each step and the components used in each step in more detail.

[0037] The ceramic substrate (A) mentioned in the first step is a substrate capable of providing some form of heat dissipation in a printed circuit board. There are no particular restrictions on the type of components used on the ceramic substrate, as long as they can provide heat dissipation.

[0038] In one embodiment, the ceramic substrate (A) may include at least one of Si3N4, AlN, or Al2O3. Specifically, the ceramic substrate (A) may include at least one selected from Si3N4 and AlN.

[0039] In one embodiment, the ceramic substrate (A) may comprise at least Si3N4. The flexural strength of Si3N4 is typically in the range of 600 MPa to 1400 MPa, which is the highest among ceramics. Furthermore, Si3N4 is a material that can be used at high temperatures because it has a flexural strength of approximately 3.2 × 10⁻⁶ MPa. -6 Si3N4 has a low coefficient of thermal expansion of approximately 3.2 g / cm³. Furthermore, Si3N4 has a density of approximately 3.2 g / cm³. 3 Si3N4 exhibits a thermal conductivity ranging from 30 to 178 W / (m·K) and high thermal shock resistance ranging from 800 K to 1000 K. Therefore, Si3N4 with these properties is an effective heat dissipation material. Consequently, printed circuit boards manufactured using boards containing Si3N4 can be used as circuit boards with excellent heat dissipation performance.

[0040] There are no particular restrictions on the process or method used to manufacture the ceramic substrate (A).

[0041] For example, a ceramic substrate (A) can be manufactured by processes including slurry preparation of ceramic powder, tape casting, stamping, firing, sintering, etc.

[0042] The slurry preparation process can be a process of preparing a slurry by mixing an organic solvent, sintering aid, plasticizer, and dispersant with powder. In this case, the ceramic powder may include at least one or more of Si3N4 powder, AlN powder, or Al2O3 powder. A ball mill or similar device can be used to prepare the powder. In this case, the average particle size of the powder is preferably 0.8 μm or less. Here, the average particle size refers to the median particle size in the particle size distribution of the n particles used. For example, when 100 particles are arranged in order from largest to smallest, the size of the 50th particle can be called the average particle size.

[0043] In one embodiment, when using Si3N4 powder, the Si3N4 powder may include at least one of β-Si3N4 or α-Si3N4. When β-Si3N4 and α-Si3N4 are mixed and used as Si3N4 powder, there are no particular limitations on the content (e.g., weight) ratio between the components to be mixed.

[0044] There are no particular restrictions on the type of organic solvent, but for example, at least one selected from toluene, benzene, xylene, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), ethanol, butanol, or methanol can be used.

[0045] There are no particular restrictions on the type of sintering aid, but for example, oxides of rare earth elements, oxides of alkaline earth metals, or combinations thereof can be used.

[0046] There are no particular restrictions on the type of plasticizer. For example, at least one selected from di-2-ethylhexyl phthalate, di-n-butylbutyrate, butyl phthalate, polyethylene glycol, or di-n-octyl phthalate can be used as a plasticizer.

[0047] There are no particular limitations on the dispersant, and at least one selected from polyester dispersants, polyacrylate dispersants, polyurethane dispersants, or polyether dispersants can be used, for example.

[0048] Casting can be a process of producing ceramic tapes (e.g., Si3N4 tapes) by applying a slurry to a polymer film of a predetermined thickness and then passing the slurry through a drying chamber.

[0049] Stamping can be a process of manufacturing ceramic green sheets (e.g., Si3N4 green sheets) by pressing and cutting ceramic strips.

[0050] The firing process can be performed by heat-treating the green sheet (e.g., Si3N4 green sheet). Specifically, the firing process can be performed by heat treatment in an air or nitrogen atmosphere. There are no particular limitations on the specific heat treatment conditions, but for example, the heat treatment can be carried out at a temperature of 400°C to 800°C for 6 to 18 hours.

[0051] The sintering process can be a process for sintering degreased green sheets (e.g., Si3N4 green sheets). Sintering can be carried out by pressure sintering (GPS). There are no particular restrictions on the specific pressure sintering conditions, but for example, the sintering process can use a pressure sintering furnace that forms a temperature of 1600°C to 2000°C, a nitrogen atmosphere, and a pressure of 8 to 12 atmospheres.

[0052] After sintering, a ceramic substrate (A) comprising at least one of Si3N4, AlN, or Al2O3 can be manufactured by post-processing including grinding.

[0053] The ceramic substrate (A) manufactured by the above process can have an upper surface and a lower surface with an area of ​​S that are opposite each other. A The substrate. In this context, the terms "upper surface" and "lower surface" are merely terms used to describe the relative positions of two surfaces facing each other, and do not indicate absolute positions.

[0054] There are no particular limitations on the shape of the ceramic substrate or the upper and lower surfaces forming the substrate. For example, the ceramic substrate can be a plate, and the upper and lower surfaces can be polygonal (e.g., quadrilateral) or circular.

[0055] In one embodiment, the shape (or area S) of the upper and lower surfaces of the ceramic substrate (A) facing each other is... A The visible shape can be rectangular. While there are no particular restrictions, it must have a rectangular area S. A The ceramic substrate (A) can be, for example, 150 mm to 220 mm wide and 100 mm to 160 mm long.

[0056] In addition, although there are no particular restrictions, the thickness of the ceramic substrate can be in the range of 0.05mm to 2.0mm.

[0057] According to a specific embodiment of this application, a deposition layer can be formed on the upper and lower surfaces of a ceramic substrate (A) facing each other, thereby forming the ceramic substrate (A). As described above, the opposing upper and lower surfaces on which the deposition layer is formed can have an area S. A .

[0058] After applying the hot pressing described below, the deposited layer can bond the metal sheet and the ceramic substrate.

[0059] There are no particular limitations on the deposition (process) used to form the deposited layer. For example, known deposition methods can be used, such as sputtering for physical vapor deposition (PVD) or chemical vapor deposition (CVD).

[0060] Although there are no particular restrictions, the area of ​​the deposited layer formed on the ceramic substrate can be S. A 50% to 100% of the area. For example, the deposited layers formed on the upper and lower surfaces of the ceramic substrate (A) can have the same area size as the upper and lower surfaces.

[0061] In one embodiment, the deposited layers formed on the upper and lower surfaces of the ceramic substrate (A) may have the same area shape as the deposited layers on the upper and lower surfaces. In this case, the fact that the area shape is the same includes not only the case that both the area and the shape are the same, but also the case that the geometry of the area is similar to each other (similar shape), even if the size of the area is different.

[0062] In one embodiment, the deposited layers formed on the upper and lower surfaces of the ceramic substrate (A) may have the same area size and area shape as the upper and lower surfaces on which the deposited layers are formed.

[0063] There are no particular restrictions on the type of component used to form the deposited layer. For example, the deposited layer may include at least one of Ag or Ti.

[0064] In one embodiment, the deposited layer may include Ag or Ti. Specifically, the deposition rate of Ag per unit area in the deposited layer may be 3.50 g / m². 2 Up to 6.10 g / m 2 The deposition rate of Ti per unit area can be 0.61 g / m². 2 Up to 1.30 g / m 2 In this context, "deposition amount per unit area" can refer to the depositional composition (Ti or Ag) relative to the area (m²) of the depositional layer formed by deposition. 2 The content (g) of the sediment layer can be increased by adjusting the composition and deposition amount as described above.

[0065] In one embodiment, the deposition rate of Ti per unit area in the deposition layer can be 0.61 g / m². 2 Up to 1.30 g / m 2 Within this range. For providing stronger bonding between the metal sheet and the ceramic substrate, the Ti deposition rate per unit area is preferably 1.02 g / m². 2 Up to 1.30 g / m 2 Within the range, more preferably within 1.04 g / m 2 Up to 1.20 g / m 2 Within the range.

[0066] In one embodiment, the deposition rate of Ag per unit area in the deposition layer can be 3.50 g / m². 2 Up to 6.10 g / m 2 Within this range. For providing stronger bonding strength between the metal sheet and the ceramic substrate, the Ag deposition rate per unit area is preferably 4.00 g / m². 2 Up to 4.60 g / m 2 Within the range.

[0067] As a result of forming deposition layers on the upper and lower surfaces of the ceramic substrate (A) facing each other as described above, it is possible to manufacture a ceramic substrate (A) with an upper deposition layer and a lower deposition layer formed on the upper and lower surfaces facing each other, respectively. In this case, the upper deposition layer is the deposition layer formed on the upper surface, and the lower deposition layer is the deposition layer formed on the lower surface.

[0068] As described below regarding steps three and four, the upper deposited layer may be disposed facing the upper metal sheet B, and the lower deposited layer may be disposed facing the lower metal sheet B'. These deposited layers can be used as a medium for bonding the metal sheets (B, B') and the ceramic substrate (A) through subsequent hot pressing.

[0069] In one embodiment, at least one of the upper and lower deposited layers may include a first deposited layer and a second deposited layer having compositions different from each other. Specifically, the first deposited layer may include Ti, and the second deposited layer may include Ag. In this case, the first deposited layer refers to the layer closer to the ceramic substrate (A) than the second deposited layer. That is, the first deposited layer may refer to the layers formed on the upper and lower surfaces of the ceramic substrate, and the second deposited layer may refer to the layer formed on the first deposited layer. For example, as... Figure 1 As shown, a first deposition layer 210 can be formed on the ceramic substrate 100, and a second deposition layer 220 can be formed on the first deposition layer.

[0070] Regarding the first and second deposition layers, the deposition (process) of this method includes: forming (depositing) a first deposition layer containing Ti on the upper and lower surfaces of a ceramic substrate (A), respectively; and forming (depositing) a second deposition layer containing Ag on the first deposition layer. Therefore, as... Figure 1 As shown, the second deposition layer 220, the first deposition layer 210, the ceramic substrate 100, the first deposition layer 210 and the second deposition layer 220 are arranged in sequence. A laminate (i.e., a ceramic substrate (A)) can be manufactured.

[0071] In one embodiment, the first deposited layer may refer to a deposited layer formed directly on the upper and lower surfaces of a ceramic substrate.

[0072] In one embodiment, the second deposition layer may refer to a deposition layer formed directly on the first deposition layer.

[0073] Although there are no specific restrictions, the area on which the first and second deposition layers are formed on the ceramic substrate can be S. A 50% to 100% of the area.

[0074] In one embodiment, the first deposition layer may have the same area and shape as the upper and lower surfaces.

[0075] In one embodiment, the first deposition layer may have the same area size and area shape as the upper and lower surfaces.

[0076] In one embodiment, the second deposition layer may have the same area and shape as the first deposition layer.

[0077] In one embodiment, the second deposition layer may have the same area size and area shape as the first deposition layer.

[0078] In one embodiment, the deposition rate of Ti per unit area in the first deposition layer can be 0.61 g / m². 2 Up to 1.30 g / m 2Within this range. Specifically, the deposition rate of Ti per unit area can reach 1.02 g / m². 2 Up to 1.30 g / m 2 Within the range, more specifically within 1.04 g / m 2 Up to 1.20 g / m 2 Within this range. This range of Ti deposition amount is preferred in terms of providing stronger bonding strength between the metal sheet and the ceramic substrate.

[0079] In one embodiment, the deposition rate of Ag per unit area in the second deposition layer can be 3.50 g / m². 2 Up to 6.10 g / m 2 Within this range. Specifically, given the stronger bonding strength between the metal sheet and the ceramic substrate, the Ag deposition rate per unit area is preferably 4.00 g / m². 2 Up to 4.60 g / m 2 Within the range.

[0080] The second step is to prepare the upper metal sheet (B) and lower metal sheet (B') to be positioned on the upper and lower deposition layers. For example, as... Figure 1 As shown, two prepared metal sheets 300 are located on each deposition layer 200.

[0081] To explain the method of performing the third and fourth steps, the second step of preparing the metal sheet (B) has been described as being performed after the first step of manufacturing the ceramic substrate (A), but changing the order of the first and second steps is an obvious variation that can be made by those skilled in the art.

[0082] In specific embodiments of this application, the metal sheets (B, B') used have a surface with a predetermined area size. Specifically, the area S of one surface of metal sheets B and B' is... B The area S is greater than the area of ​​the upper and lower surfaces of the ceramic substrate. A More specifically, the area S on one side of metal sheet B B It is the area S A 1.5 times. As described below, having an area S B The metal sheet allows two or more ceramic substrates A to be arranged side by side on an area S. B It is located on one side of the plane, and therefore production costs can be reduced.

[0083] In one embodiment, the area S B It can be the area S A Less than 6.0 times, less than 5.0 times, less than 4.0 times, less than 3.0 times, or less than 2.5 times. More specifically, the area S B It can be the area S AMore than 1.6 times, more than 1.7 times, more than 1.8 times, more than 1.9 times, or more than 2.0 times, and less than 2.4 times, less than 2.3 times, less than 2.2 times, or less than 2.1 times. When the area S B If the etching solution is too large, there may be problems such as the etching solution not being washed away properly and accumulating on the substrate (etching solution residue) or uneven etching.

[0084] In one embodiment, the shape of the metal sheet may be the same as that of the ceramic substrate.

[0085] In a specific embodiment of this application, when the ceramic substrate has an area S A The upper and lower surfaces, as well as the metal sheets B and B', have an area S B When one surface has a rectangular shape, the dimensions of metal sheets B and B' can be, for example, a width of 250 mm to 300 mm and a length of 160 mm to 210 mm.

[0086] In addition, although there are no particular restrictions, the thickness of metal sheets B and B' can be in the range of 0.05 mm to 3.0 mm.

[0087] There are no particular restrictions on the type of metal included in the metal sheet (B). For example, the metal sheet (B) may include one or more selected from Cu, Al, Ni or Fe.

[0088] The third step is to arrange the ceramic substrate A and the metal sheets B and B' such that two or more ceramic substrates A are positioned side-by-side on the metal sheets in a plane. According to a specific embodiment of this application, the two or more ceramic substrates A may have the same size and shape.

[0089] Specifically, the third step makes the area of ​​the upper metal sheet B and the lower metal sheet B' of the two or more ceramic substrates A facing each other S. B They are positioned side-by-side in a plane between one surface. This is the procedure for setting up metal sheets (B, B') and two or more ceramic substrates (A).

[0090] Regarding the three steps above, the fact that two or more ceramic substrates A are positioned side by side in the plane means that the two or more ceramic substrates A positioned on the metal sheets B and B' do not overlap each other, i.e., they are not laminated. Therefore, the two or more ceramic substrates A positioned on the metal sheet by the third step have no overlapping area, and the overlapping area between the ceramic substrates A is zero.

[0091] According to the arrangement in the third step, the upper metal sheet (B) is positioned such that the upper metal sheet (B) has an area S BOne side faces the deposited layer (on all two or more ceramic substrates). Furthermore, the lower metal sheet (B') is positioned such that the lower metal sheet (B') has an area S B One surface faces the lower deposition layer (of all two or more ceramic substrates). Then, in a subsequent fourth hot-pressing step, two or more ceramic substrates (A) positioned side-by-side between metal sheets (B, B') in a plane (via the upper and lower deposition layers) are bonded to the metal sheets (B, B'). For example, the upper metal sheet (B) is bonded to the upper surface of all two or more ceramic substrates via the upper deposition layer. The lower metal sheet B' is bonded to the lower surface of all two or more ceramic substrates via the lower deposition layer.

[0092] In one embodiment, the upper deposition layer may be configured to directly contact or directly face the metal sheet, having an area S B One of the surfaces.

[0093] In one embodiment, the lower deposition layer may be configured to directly contact or directly face the metal sheet, having an area S B One of the surfaces.

[0094] In one embodiment, regarding the arrangement of the metal sheets (B, B') and the ceramic substrate (A), in the third step, a surface area S is defined. B The overlap area between one surface of a metal sheet and two or more ceramic substrates A can be made such that it is more than 70% of the total area of ​​the ceramic substrates (A) located between the upper metal sheet (B) and the lower metal sheet (B') (total area S). T =n×S A Where n is a natural number equal to or greater than 2 and refers to the number of ceramic substrates located between the metal sheets (B, B'). For example, the overlap area is more than 75%, more than 80%, more than 85%, more than 90%, or greater than 95% of the total area of ​​the ceramic substrate (A) located between the upper metal sheet (B) and the lower metal sheet (B').

[0095] Hot pressing, which will be described later, can be performed on the laminate arranged as described above. When hot pressing is performed, two or more ceramic substrates (A) positioned side by side on the same plane between the upper metal sheet (B) and the lower metal sheet (B') are deposited between the upper metal sheet (B) and the lower metal sheet (B') through a deposited layer or a structure derived therefrom.

[0096] In related technologies, ceramic substrates and metal sheets with the same area are typically combined. However, in this application, an area (S) is used. B ) represents the area (S) of the ceramic substrate. A At least 1.5 times the weight of the metal sheet (see) Figure 2In the manufacture of printed circuit boards, etching is performed, and with the above arrangement, if two or more ceramic substrates are to undergo a single etching process, the effective area increases and more etched wafers can be produced. Furthermore, the amount of waste is reduced. In related technologies, one substrate to be etched is placed in the etching process line, but with the arrangement described above, two substrates are placed in the etching line compared to related technologies. Therefore, there is an effect of shortening processing time and reducing related costs (e.g., labor costs). Furthermore, in the printing process, a process of attaching a protective film to the un-etched portion can be added. As described above, since there is an effect of attaching the film to the area of ​​two wafers, there is an effect of reducing the time and cost (e.g., labor costs) of related processes. Therefore, production costs can be reduced according to this application.

[0097] In one embodiment, regarding the arrangement of the metal sheets (B, B') and ceramic substrates (A), at least two ceramic substrates A may be disposed on one surface of the metal sheets, spaced a predetermined distance from the edges of the metal sheets B and B'. When spaced from the edges of the metal sheets, the position to be clamped by a fixture can be fixed during the process. Therefore, since the distance between the two or more ceramic substrates becomes closer, dead zones are reduced and waste of raw materials can be prevented.

[0098] According to a specific embodiment of this application, a set of master cards formed from non-bonded laminates can be obtained through the above three steps. The non-bonded laminates have a structure of metal sheet (B) / two or more ceramic substrates (A) (positioned side by side in a plane) / metal sheet (B').

[0099] In one embodiment, the method may further include manufacturing a master card stack. In this case, anti-adhesion sheets formed of different materials may be inserted between each group to prevent adhesion between the metal sheets 300. The anti-adhesion sheets described above may include, for example, graphite. Although not particularly limited, known bonding techniques or bonding materials may be used to form the stack.

[0100] The fourth step is to bond the upper metal sheet B and the lower metal sheet B' located on the deposited layer to the ceramic substrate A by hot pressing.

[0101] In the fourth step, for example, at a temperature of 450°C to 1300°C and a pressure of 1 MPa to 25 MPa, hot pressing of the metal sheets (B, B') can be performed simultaneously in the direction of the ceramic substrate (A). Although not particularly limited, hot pressing can, for example, be performed over approximately 10... -1 Up to 10 -5 The process is carried out in a vacuum atmosphere.

[0102] In one embodiment, the lower limit of the combined temperature can be above 500°C, above 600°C, above 700°C, or above 800°C. Furthermore, the upper limit can be, for example, below 1050°C, below 1000°C, below 950°C, or below 900°C.

[0103] In one embodiment, the lower limit of the pressure during bonding can be, for example, above 5 MPa or above 10 MPa. Furthermore, the upper limit can be, for example, below 20 MPa or below 15 MPa.

[0104] Metal sheets B and B' can be bonded to a ceramic substrate A via hot pressing, through a deposited layer (or a layer including components derived from the deposited layer). For example, Figure 3 This is a schematic diagram showing a cross-sectional view of a substrate or laminate obtained after the bonding step according to an embodiment of this application. For example... Figure 3 As shown, the laminate obtained after bonding has a structure in which a bonding layer 200a and a metal sheet 300 are sequentially formed on the upper and lower surfaces of the ceramic substrate 100, respectively. At this time, the bonding layer 200a is a deposited layer or a layer derived from a deposited layer that has undergone the bonding step.

[0105] Reference Figure 1 as well as Figures 3 to 5 The diffusion between materials in each of the ceramic substrate 100, the deposited layer 200, and the metal sheet 300 can be achieved by hot pressing. For example, when Ti is included in the first deposited layer 210 and Si3N4 is included in the ceramic substrate (A) 100, a reaction as shown in Scheme 1 can occur between Ti and Si3N4.

[0106] [Option 1]

[0107] 4Ti + Si3N4 → 3Si + 4TiN

[0108] In other words, by hot pressing, the materials included in the deposition layer 200 and the materials included in the ceramic substrate 100 can react to form a bonding layer 200a, and the bonding layer 200a may include TiN.

[0109] According to this embodiment, the bonding layer 200a is a TiN-containing layer and can be used as a strong bonding medium layer between the ceramic substrate 100 and the metal sheet 300. That is, the bonding layer 200a can be formed by a diffusion bonding method to perform the bonding between the ceramic substrate 100 and the metal sheet 300.

[0110] As described above, in the deposition step, the deposition rate of Ag per unit area contained in the second deposition layer 220 can be 3.50 g / m². 2 Up to 6.10 g / m 2Within this range. More specifically, the amount of Ag deposited per unit area in the second deposition layer 220 can, for example, be 4.00 g / m³. 2 Up to 4.60 g / m 2 Within a certain range. When bonding between layers comprising different materials is performed, desorption between layers can easily occur when stress transfer occurs in the layer comprising a material with relatively low strength. Therefore, increasing the strength of the layer comprising a material with relatively low strength can more effectively improve the bonding strength in the bonding between layers comprising different materials. For example, Ag included in the second deposition layer 220 diffuses toward the metal sheet 300 comprising Cu during hot pressing to compensate for the weak strength of the metal sheet 300 at the interface. Based on the above principle, Ag included in the second deposition layer 220 can improve the bonding strength between the ceramic substrate 100 and the metal sheet 300. Furthermore, Ag included in the second deposition layer 220, together with Ti included in the first deposition layer 210 and Cu included in the metal sheet 300, forms a liquid phase consisting of a Cu-Ti-Ag ternary system. This can help promote the formation of the reaction layer by improving wettability.

[0111] When the amount of Ag deposited per unit area in the second deposition layer 220 is less than the aforementioned range, the strength of the metal sheet 300 cannot be sufficiently increased, resulting in poor bonding strength between the ceramic substrate 100 and the metal sheet 300. Furthermore, when the amount of Ag deposited per unit area in the second deposition layer 220 exceeds the aforementioned range, more Ag than necessary can be deposited. Therefore, a problem arises where the bonding strength between the ceramic substrate 100 and the metal sheet 300 is significantly reduced due to the formation of undiffused Ag residue.

[0112] The Ti deposition rate per unit area in the first deposition layer 210 is 0.61 g / m³. 2 Up to 1.30 g / m 2 Within a certain range, specifically, for example, preferably within 1.02 g / m³. 2 Up to 1.30 g / m 2 Within the range, and 1.04 g / m 2 Up to 1.20 g / m 2 The range is more preferred. The deposition amount of Ti per unit area is related to the thickness of the bonding layer 200a, which affects the bonding strength between the ceramic substrate 100 and the metal sheet 300.

[0113] When the amount of Ti deposited per unit area in the first deposition layer 210 is less than the aforementioned range, the thickness of the bonding layer 200a is insufficient, resulting in poor bonding strength between the ceramic substrate 100 and the metal sheet 300. For example, as shown in the comparative example below, the bonding strength between the ceramic substrate 100 and the metal sheet 300 can be less than 9 N / mm. Furthermore, when the amount of Ti deposited per unit area in the first deposition layer 210 exceeds the aforementioned range, the deposition amount reaches a saturation value, thus the increase in bonding strength is small, resulting in wasted material.

[0114] As described above, in the method for manufacturing a printed circuit board according to this application, the deposition amount of Ag per unit area is adjusted to 3.50 g / m². 2 Up to 6.10 g / m 2 The range was adjusted, and the deposition rate of Ti per unit area was adjusted to 0.61 g / m². 2 Up to 1.30 g / m 2 This range allows for the fabrication of substrates for printed circuits with excellent interlayer bonding strength. Therefore, even when the printed circuit board manufactured as described above is exposed to repeated thermal shock environments, peeling does not occur or peeling is greatly suppressed.

[0115] In one embodiment, the method may further include an etching step for metal sheets B and B B'. Specifically, after the bonding step, a substrate for printed circuits can be manufactured relative to the bonded ceramic substrate 100 and / or metal sheet 300 using a resist printing process, an etching process, an electroplating process, etc.

[0116] exist Figure 2 In the diagram, the arrow indicates the direction of hot pressing, and the master card (MC) refers to a laminate in the form of a metal sheet / ceramic substrate / metal sheet. This invention combines two ceramic substrates arranged side-by-side on a plane, resulting in higher yield and lower etching unit cost compared to existing technologies.

[0117] Figure 4 This is a cross-sectional image taken after the deposition step and before the bonding step. From Figure 4 It can be seen that a first deposition layer 210 containing Ti and a second deposition layer 220 containing Ag are formed on the ceramic substrate 100.

[0118] Figure 5 This is a cross-sectional view after the steps are combined. From Figure 5 It can be confirmed that the bonding layer 200a is formed by diffusion bonding after the bonding step, so the ceramic substrate 100 and the metal sheet 300 are bonded.

[0119] In the following description, the operation and effects of the invention will be described in more detail through specific embodiments thereof. However, this is presented as an example of the invention and is therefore not intended to limit the scope of the invention in any way.

[0120] Manufacturing example (manufacturing of ceramic substrate (A))

[0121] Si3N4 powder with an average particle size of less than 0.8 μm was prepared by ball milling. Organic solvents (e.g., toluene, methanol, ethanol), sintering aids (e.g., Y2O3, MgO), plasticizers (e.g., di-n-octyl phthalate (DOP), polyethylene glycol (PEG)), and dispersants (e.g., BYK-111) were added to the Si3N4 powder to prepare a slurry, which was then passed through a drying chamber to prepare Si3N4 strips. Si3N4 green sheets were prepared by pressing and cutting the Si3N4 strips, and then sintered by heat treatment at 600 °C for 12 hours. Subsequently, a ceramic substrate (A) (silicon nitride Si3N4 substrate) with predetermined dimensions (190 mm wide x 138 mm long x 0.32 mm thick) was prepared by sintering under a nitrogen atmosphere at 1850 °C and 1 MPa using a gas pressure sintering method.

[0122] Experiment 1: Confirmation of Production Cost Reduction

[0123] Ti (first deposition layer) and Ag (second deposition layer) are sequentially deposited on the opposing upper and lower surfaces of the ceramic substrate in the production embodiment. At this point, approximately 1.0 g / m² is deposited. 2 Ti, and deposited at approximately 6.08 g / m³. 2 Ag. Two ceramic substrates (A) are prepared and deposited on the upper and lower surfaces of a first and second deposition layer facing each other.

[0124] In addition, two copper sheets with dimensions of 270mm x 190mm x 0.3mm were prepared.

[0125] After placing the copper sheet, two ceramic substrates (A) are placed adjacent to each other on one surface of the copper sheet to minimize the gap between the two ceramic substrates (A). (At this point, two or more ceramic substrates (A) are placed side by side in a plane on the copper sheet, and the deposited layer (Ag deposited layer) of each ceramic substrate (A) is set to contact the copper sheet.) A non-bonded laminate in the form of copper sheet / two ceramic substrates (A) (placed side by side in a plane) / copper sheet is produced by placing the remaining copper sheet on top in the same manner. At this point, the overlap area between the two ceramic substrates and the copper sheet is approximately 90%.

[0126] Subsequently, in approximately 10 -4The laminate was processed using a hot press while being pressed at 15 MPa under a Turbo atmosphere and at a temperature of approximately 980°C. As a result, a sample of copper sheet / two ceramic substrates (A) (positioned side by side in a plane) / copper sheet in which copper sheet and silicon nitride substrate are bonded to each other was obtained.

[0127] Copper is etched using a sample to fabricate copper circuits. Specifically, after attaching a dry film to both sides of the outer side of the laminate, UV light is irradiated onto the film, leaving the un-etched copper portions (circuit portions), and the film in the remaining portions excluding the circuit portions is peeled off. This is then placed into an etching line for copper etching.

[0128] As a result, compared to two comparative samples where the ceramic substrates were etched one after another (copper sheet / one ceramic substrate (A) / copper sheet), the time required to manufacture the same number of circuits can be reduced by almost half when etching the sample manufactured as described in this application (copper sheet / two ceramic substrates (A) (placed side by side) / copper sheet). Furthermore, it was confirmed that more circuit boards can be produced even during the same etching process time (e.g., yield increased by approximately 30% or more). Therefore, according to this application, the cost reduction effect is significant.

[0129] Experimental Example 2: Joint Strength Assessment

[0130] According to ASTM D6682, the bond strength (N / mm) of the samples from Examples 1 to 6 and Comparative Examples 1 to 6 was measured. Specifically, samples with a copper sheet / silicon nitride substrate / copper sheet structure were etched, wherein the copper sheet and silicon nitride substrate were bonded to each other, and samples in which a copper strip with a width of 5 mm and a length of 100 mm was bonded to a ceramic substrate were prepared. Approximately 10 mm of the end of the copper strip was manually separated before testing so that the copper strip could be held in place by the clamps of a universal testing machine (equipment manufacturer and model name: Ametek, LS5). The sample was fixed in the universal testing machine, the copper strip was held in place by the clamps, and the separation was performed at a speed of 50 mm / min, and the stress was measured to calculate the bond strength.

[0131] The results are shown in Table 1-3 below.

[0132] Example 1 (Ti deposition rate 1.076 g / m³) 2 Ag deposition amount 4.005 g / m 2 )

[0133] A first deposition layer was formed by depositing 0.0282 g of Ti on the ceramic substrate of the preparation example by sputtering for 70 seconds. Then, a second deposition layer was formed by depositing 0.105 g of Ag on the first deposition layer for 30 seconds. At this time, the formation area of ​​the first and second deposition layers was adjusted to be the same as the formation area of ​​the ceramic substrate (A) (width 190 mm x length 138 mm). Here, the deposition amount of Ti per unit area was 1.076 g / m². 2 The deposition rate of Ag per unit area is 4.005 g / m². 2 .

[0134] In addition, two ceramic substrates (A) and two copper sheets (270 mm wide x 185 mm long x 0.3 mm thick) as described above are prepared. The two ceramic substrates (A) are placed on one side of a prepared copper sheet, adjacent to each other to minimize gaps (at this point, the two ceramic substrates (A) are placed side-by-side in the plane of the copper sheet, and the deposited layer (a second deposited layer containing Ag) of each ceramic substrate (A) is positioned in contact with the copper sheet). The remaining copper sheet is placed on the two ceramic substrates (A) in the same manner to prepare a non-bonded laminate in the form of copper sheet / two ceramic substrates (A) (placed side-by-side in the plane) / copper sheet. At this point, the overlap area between the two ceramic substrates and the copper sheet is approximately 95%.

[0135] Subsequently, in approximately 10 -4 Hot-pressed laminates are formed in a terrine atmosphere at a temperature of 980°C and a pressure of 15MPa.

[0136] Through the above series of processes, a sample consisting of Cu metal sheet, TiN bonding layer and Si3N4 was prepared.

[0137] Example 2 (Ti deposition rate 1.194 g / m³) 2 Ag deposition amount 4.005 g / m 2 )

[0138] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that the first layer was formed by depositing 0.0313 g of Ti. In this case, the deposition amount of Ti per unit area was 1.194 g / m². 2 Furthermore, the deposition rate of Ag per unit area is 4.005 g / m². 2 .

[0139] Example 3 (Ti deposition rate 1.030 g / m³) 2 Ag deposition amount 5.339 g / m³ 2 )

[0140] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that 0.0270 g of Ti was deposited to form the first layer and 0.1400 g of Ag was deposited to form the second layer. In this case, the deposition amount of Ti per unit area was 1.030 g / m². 2 Furthermore, the deposition rate of Ag per unit area was 5.339 g / m². 2 .

[0141] Example 4 (Ti deposition rate 1.220 g / m³) 2 Ag deposition amount 5.339 g / m³ 2 )

[0142] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that 0.0320 g of Ti was deposited to form the first layer and 0.1400 g of Ag was deposited to form the second layer. In this case, the deposition amount of Ti per unit area was 1.220 g / m². 2 Furthermore, the deposition rate of Ag per unit area was 5.339 g / m². 2 .

[0143] Example 5 (Ti deposition rate 1.003 g / m³) 2 Ag deposition amount 4.005 g / m 2 )

[0144] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that the first layer was formed by depositing 0.0263 g of Ti. In this case, the deposition amount of Ti per unit area was 1.003 g / m². 2 Furthermore, the deposition rate of Ag per unit area is 4.005 g / m². 2 .

[0145] Example 6 (Ti deposition amount 0.961 g / m³) 2 Ag deposition amount 4.005 g / m 2 )

[0146] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that the first layer was formed by depositing 0.0252 g of Ti. In this case, the deposition amount of Ti per unit area was 0.961 g / m². 2 Furthermore, the deposition rate of Ag per unit area is 4.005 g / m². 2 .

[0147] Comparative Example 1 (Ti deposition amount 0.374 g / m³) 2 Ag deposition amount 2.868 g / m2 )

[0148] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that 0.0098 g of Ti was deposited to form the first layer and 0.0752 g of Ag was deposited to form the second layer. In this case, the deposition amount of Ti per unit area was 0.374 g / m². 2 Furthermore, the deposition rate of Ag per unit area was 2.868 g / m². 2 .

[0149] Comparative Example 2 (Ti deposition amount 0.599 g / m³) 2 Ag deposition amount 2.868 g / m 2 )

[0150] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that 0.0157 g of Ti was deposited to form the first layer and 0.0752 g of Ag was deposited to form the second layer. In this case, the deposition amount of Ti per unit area was 0.599 g / m². 2 Furthermore, the deposition rate of Ag per unit area was 2.868 g / m². 2 .

[0151] Comparative Example 3 (Ti deposition amount 0.843 g / m³) 2 Ag deposition amount 2.868 g / m 2 )

[0152] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that 0.0221 g of Ti was deposited to form the first layer and 0.0752 g of Ag was deposited to form the second layer. In this case, the deposition amount of Ti per unit area was 0.843 g / m². 2 Furthermore, the deposition rate of Ag per unit area was 2.868 g / m². 2 .

[0153] Comparative Example 4 (Ti deposition amount 1.034 g / m³) 2 Ag deposition amount 2.868 g / m 2 )

[0154] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that 0.0342 g of Ti was deposited to form the first layer and 0.0752 g of Ag was deposited to form the second layer. In this case, the deposition amount of Ti per unit area was 1.304 g / m². 2 Furthermore, the deposition rate of Ag per unit area was 2.868 g / m². 2 .

[0155] Comparative Example 5 (Ti deposition amount 1.041 g / m³) 2 Ag deposition amount 6.808 g / m³ 2 )

[0156] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that 0.0273 g of Ti was deposited to form the first layer and 0.1785 g of Ag was deposited to form the second layer. In this case, the deposition amount of Ti per unit area was 1.041 g / m². 2 Furthermore, the deposition rate of Ag per unit area was 6.808 g / m². 2 .

[0157] Comparative Example 6 (Ti deposition amount 0.599 g / m³) 2 Ag deposition amount 4.005 g / m 2 )

[0158] A sample comprising a Cu metal sheet, a TiN bonding layer, and a Si3N4 ceramic substrate was prepared in the same manner as in Example 1, except that the first layer was formed by depositing 0.0157 g of Ti. At this point, the deposition amount of Ti per unit area was 0.599 g / m². 2 Furthermore, the deposition rate of Ag per unit area is 4.005 g / m². 2 .

[0159] [Table 1]

[0160]

[0161] [Table 2]

[0162] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Ti deposition amount (g) 0.0098 0.0157 0.0221 0.0342 0.0273 Ag deposition amount (g) 0.0752 0.0752 0.0752 0.0752 0.1785 <![CDATA[The deposition amount per unit area of Ti (g / m 2 )]]> 0.374 0.599 0.843 1.304 1.041 <![CDATA[The deposition amount of Ag per unit area (g / m 2 )]]> 2.868 2.868 2.868 2.868 6.808 Bond strength (N / mm) 0.6 3.7 4.8 7.5 15.6

[0163] [Table 3]

[0164] Example 5 Example 6 Comparative Example 6 Ti deposition amount (g) 0.0263 0.0252 0.0157 Ag deposition amount (g) 0.105 0.105 0.105 <![CDATA[The deposition amount per unit area of Ti (g / m 2 )]]> 1.003 0.961 0.599 <![CDATA[The deposition amount of Ag per unit area (g / m 2 )]]> 4.005 4.005 4.005 Bond strength (N / mm) 9.6 9.4 8.6

[0165] First, the samples from Examples 1 and 2 and Comparative Examples 1 to 4 were compared, wherein the Ag deposition rate per unit area was 3.50 g / m². 2 The samples from Examples 1 and 2 above exhibited excellent bonding strengths of 21.4 N / mm and 22.1 N / mm, respectively. On the other hand, the Ag deposition rate per unit area was less than 3.50 g / m². 2All samples from Comparative Examples 1 to 4 showed bond strength below 7.5 N / mm. In particular, although the Ti deposition per unit area was higher in Comparative Example 4 than in Examples 1 and 2, the sample in Comparative Example 4 showed a much lower bond strength due to the lower Ag content. This is considered to be a result of the change (improvement) in the strength of the metal sheet based on the amount of Ag deposition. Next, comparing the samples from Examples 1 and 3 with those from Comparative Example 5, there was no significant difference in the Ti deposition per unit area. However, the Ag deposition per unit area was 6.10 g / mm. 2 The samples from Examples 1 and 3 below exhibited excellent bonding strengths of 21.4 N / mm and 16.3 N / mm, respectively. On the other hand, the adhesion strength of the sample from Comparative Example 5 was considerably reduced to 15.6 N / mm. This is attributed to the formation of Ag residues at the interface due to excessive Ag deposition.

[0166] Next, when comparing the samples of Examples 1, 2, 5, 6 and Comparative Example 6, the deposition amount of Ag per unit area was almost the same. The deposition amount of Ti per unit area was 0.61 g / m². 2 The samples from Examples 1, 2, 5, and 6 above exhibit a bond strength of at least 9.4 N / mm. On the other hand, the deposition rate of Ti per unit area is less than 0.61 g / m². 2 The sample of Comparative Example 6 showed a low bonding strength below 8.6 N / mm. This is considered to be a result of the change (improvement) in the bonding layer strength according to the amount of Ti deposited. Specifically, the amount of Ti deposited per unit area was 1.02 g / m². 2 The samples from Examples 1 and 2 above showed excellent bonding strengths of 21.4 N / mm and 22.1 N / mm, respectively.

[0167] Next, the samples from Examples 1, 2, and 4 were examined, where the deposition rate of Ti per unit area was 1.30 g / m². 2 All samples from Examples 1, 2, and 4 below exhibited excellent bond strength of 20 N / mm or higher. However, when the Ti deposition rate per unit area was 1.02 g / m², the bonding strength was significantly lower. 2 At the above levels, even with increased Ti deposition, the improvement in bonding strength is insufficient, reaching a saturation point. Therefore, to prevent waste of raw material costs and to achieve optimal interfacial bonding strength, a Ti deposition rate of 1.30 g / m² is preferred. 2 the following.

Claims

1. A method for manufacturing a printed circuit board, the method comprising the following steps: At least one upper deposition layer is formed on the upper surface of each ceramic substrate included in a set of ceramic substrates, and at least one lower deposition layer is formed on the lower surface of each ceramic substrate included in the set of ceramic substrates, wherein the area size of the upper surface of each ceramic substrate and the area size of the lower surface of each ceramic substrate are the same. The set of ceramic substrates are arranged side-by-side between the surfaces of an upper metal sheet and a lower metal sheet, wherein the area dimensions of the surfaces of the upper metal sheet and the lower metal sheet are the same; and The upper metal sheet and the lower metal sheet are hot-pressed such that the upper metal sheet and the lower metal sheet are bonded to the set of ceramic substrates via the at least one upper deposition layer and the at least one lower deposition layer, wherein... S B ≥1.5×S A S A S is the area dimension of the upper surface of each ceramic substrate, and S B It is the area dimension of the surface of the upper metal sheet or the lower metal sheet.

2. The method according to claim 1, wherein, S B ≥P×S A , where P is a number between 1.5 and 6.

0.

3. The method according to claim 1, wherein, S B ≥P×S A , where P is a number between 1.5 and 2.

5.

4. The method according to claim 1, wherein, The set of ceramic substrates is placed between the surface of the upper metal sheet and the surface of the lower metal sheet, such that S O ≥0.7×S T , of which S O It is the dimension of the overlapping area of ​​the set of ceramic substrates and the upper metal sheet, and S T =n×S A , where n is the number of ceramic substrates included in the group of ceramic substrates.

5. The method according to claim 1, wherein, The set of ceramic substrates is placed between the surface of the upper metal sheet and the surface of the lower metal sheet, such that S O ≥0.9×S T , of which S O It is the dimension of the overlapping area of ​​the set of ceramic substrates and the upper metal sheet, and S T =n×S A , where n is the number of ceramic substrates included in the group of ceramic substrates.

6. The method according to claim 1, wherein, Each of the at least one upper deposition layer and the at least one lower deposition layer comprises Ag and Ti. The deposition rate of Ag per unit area is 3.50 g / m². 2 Up to 6.10 g / m 2 Within the range, and The deposition rate of Ti per unit area is 0.61 g / m². 2 Up to 1.30 g / m 2 Within the range.

7. The method according to claim 1, wherein, The hot pressing step is carried out at a temperature of 450°C to 1300°C while applying a pressure of 1 MPa to 25 MPa.

8. The method according to claim 6, wherein, The deposition rate of Ag per unit area is 4.00 g / m². 2 Up to 4.60 g / m 2 Within the range.

9. The method according to claim 6, wherein, The deposition rate of Ti per unit area is 1.02 g / m². 2 Up to 1.30 g / m 2 Within the range.

10. The method according to claim 5, wherein, The step of forming the at least one upper deposition layer on the upper surface of each ceramic substrate includes forming a first upper deposition layer containing Ti on the upper surface of each ceramic substrate and forming a second upper deposition layer containing Ag on the first upper deposition layer. The step of forming the at least one under-deposited layer on the lower surface of each ceramic substrate includes forming a first under-deposited layer containing Ti on the lower surface of each ceramic substrate and forming a second under-deposited layer containing Ag on the first under-deposited layer.

11. The method according to claim 1, wherein, Each ceramic substrate in the group of ceramic substrates includes at least one of Si3N4, AlN, or Al2O3.

12. The method according to claim 11, wherein, The upper metal sheet and the lower metal sheet include at least one of Cu, Al, Ni or Fe.

13. The method according to claim 11, wherein, Each of the ceramic substrates in the group comprises at least one of Si3N4 and AlN.

14. The method according to claim 12, wherein, The hot-pressing step causes a chemical reaction between the material included in the upper or lower deposited layer and the material included in each of the set of ceramic substrates. A bonding layer is formed through the aforementioned chemical reaction. The bonding layer includes at least TiN.

15. The method of claim 1, further comprising an etching step of the bonded metal sheets (B, B') and the ceramic substrate.

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