Preparation method of double-sided copper-clad ceramic substrate

Abstract

The invention discloses a preparation method of a double-sided copper-clad ceramic substrate, and belongs to the field of integrated circuit manufacturing, and the method comprises the following steps: step S1-S4, bonding a copper foil to one side of a ceramic substrate, carrying out first sintering oxidation, and forming a single-sided copper-clad ceramic substrate, and step S5-S8, bonding a copper foil to the other side of the ceramic substrate, carrying out second sintering oxidation, and forming a single-sided copper-clad ceramic substrate. In the sintering process, the copper-clad ceramic substrate is placed on a base plate, the base plate is placed on a gasket, the lower surface of the gasket makes contact with a conveying belt, a furnace bottom plate of the sintering furnace is located below the conveying belt, through holes are evenly formed in the furnace bottom plate, the hole diameter of the through holes ranges from 1 mm to 15 mm, and the aperture ratio ranges from 20% to 50%. According to the invention, the energy consumption is reduced, and the product yield is improved.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit manufacturing, and particularly to a method for preparing a double-sided copper-clad ceramic substrate. Background Art

[0002] A double-sided copper-clad ceramic substrate is a composite copper-clad ceramic plate made by directly sintering a copper foil onto the surface of Al2O3 or AlN ceramic using DBC technology, and has characteristics such as high thermal conductivity, high electrical insulation, large current capacity, high mechanical strength, and temperature characteristics matching those of silicon chips.

[0003] DBC technology uses an oxygen-containing eutectic liquid of copper to directly bond copper onto ceramics. Its basic principle is to introduce an appropriate amount of oxygen element between copper and ceramics before or during the bonding process. Within a certain temperature range, copper and oxygen form a Cu-O eutectic liquid, which infiltrates the copper foil to achieve the bonding of the ceramic substrate and the copper plate.

[0004] Currently, the mainstream sintering process in the production of double-sided copper-clad ceramic substrates is to sinter in two steps, that is, sinter one side first and then the other side. If the copper sheet is oxidized unevenly during sintering, it will cause the local oxygen content of the copper sheet to be too high or too low, resulting in uneven wettability of the product. In severe cases, the copper and ceramic will not adhere, and the two will not bond, resulting in unqualified products.

[0005] The above background art is for facilitating the understanding of the present invention and is not prior art that has been publicly known to the general public before the application of the present invention. Summary of the Invention

[0006] In view of the above defects, the present invention provides a method for preparing a double-sided copper-clad ceramic substrate, which reduces energy consumption.

[0007] The technical solution is as follows: A method for preparing a double-sided copper-clad ceramic substrate, comprising the following steps:

[0008] Step S1, coating a layer of binder on one side of a clean ceramic substrate;

[0009] Step S2, placing a clean copper foil on the ceramic substrate coated with the binder;

[0010] Step S3, pressing the stacked ceramic substrate and copper foil to firmly bond the ceramic substrate and the copper foil together to form a single-sided copper-clad copper-clad ceramic substrate;

[0011] Step S4, first sintering and oxidizing: The single-sided copper-clad copper-clad ceramic substrate is sintered through a sintering furnace by a conveyor belt, and after sintering, a single-sided copper-clad ceramic substrate is formed;

[0012] Step S5, coating a layer of binder on the other side of the ceramic substrate corresponding to the single-sided copper-clad ceramic substrate;

[0013] Step S6: Place the cleaned copper foil on the single-sided copper-clad ceramic substrate coated with the binder, ensuring good contact between the copper foil and the surface of the ceramic substrate.

[0014] Step S7: Press the stacked single-sided copper-clad ceramic substrate and copper foil to firmly bond the single-sided copper-clad ceramic substrate and the copper foil together, forming a double-sided copper-clad copper-clad ceramic substrate.

[0015] Step S8: Second sintering oxidation: The double-sided copper-clad copper-clad ceramic substrate is sintered through a sintering furnace via a conveyor belt, and after sintering, a double-sided copper-clad copper-clad ceramic substrate is formed.

[0016] In Step S4 and Step S8, during the sintering process, the copper-clad ceramic substrate is placed on a backing plate, the backing plate is placed on a gasket, the lower surface of the gasket is in contact with the conveyor belt, the furnace bottom plate of the sintering furnace is located below the conveyor belt, and through holes with a diameter of 1 - 15 mm and an opening ratio of 20 - 50% are evenly arranged on the furnace bottom plate.

[0017] Further, in Step S4 and Step S8, the sintering process sequentially includes three heating zones, three constant-temperature zones, and six cooling zones. Among them, the three heating zones are 480°C - 600°C, 600°C - 700°C, and 650°C - 700°C in sequence, the temperature of the three constant-temperature zones is 850°C - 900°C, the six cooling zones are 650°C - 700°C, 640°C - 680°C, 620°C - 660°C, 600°C - 640°C, 580°C - 620°C, and 500°C - 580°C in sequence, the passing time of the three heating zones is 9 - 13 min, the passing time of the three constant-temperature zones is 14 - 18 min, the passing time of the three cooling zones is 9 - 13 min, and the conveying speed of the conveyor belt is 80 - 85 mm / min.

[0018] Further, in Step S4 and Step S8, the sintering process sequentially includes three heating zones, three constant-temperature zones, and six cooling zones. Among them, the three heating zones are 480°C - 600°C, 600°C - 700°C, and 650°C - 700°C in sequence, the temperature of the three constant-temperature zones is 750°C - 700°C, the six cooling zones are 650°C - 700°C, 640°C - 680°C, 620°C - 660°C, 600°C - 640°C, 580°C - 620°C, and 500°C - 580°C in sequence, the passing time of the three heating zones is 9 - 13 min, the passing time of the three constant-temperature zones is 14 - 18 min, the passing time of the three cooling zones is 9 - 13 min, and the conveying speed of the conveyor belt is 80 - 85 mm / min.

[0019] Further, in the steps S4 and S8, the sintering process sequentially includes three heating zones, three constant-temperature zones, and six cooling zones. Among them, the three heating zones are 480°C - 600°C, 600°C - 700°C, and 650°C - 700°C in sequence; the temperatures of the three constant-temperature zones are 710°C - 830°C; the six cooling zones are 650°C - 700°C, 640°C - 680°C, 620°C - 660°C, 600°C - 640°C, 580°C - 620°C, and 500°C - 580°C in sequence. The passing times of the three heating zones are 9 - 13 min, the passing times of the three constant-temperature zones are 14 - 18 min, the passing times of the three cooling zones are 9 - 13 min, and the conveying rate of the conveyor belt is 80 - 85 mm / min.

[0020] Further, the gasket material is alumina with a thickness of 5 - 10 mm; the backing plate is a magnesium oxide foamed ceramic backing plate with a thickness of 5 - 10 mm, a pore diameter of 0.08 - 3 mm, and a porosity of 25 - 30%, and the conveyor belt is a mesh conveyor belt.

[0021] Further, the through-hole diameter is 3 - 7 mm, and the opening ratio is 30 - 35%. Description of the Drawings

[0022] Figure 1 is a schematic structural state diagram of the copper-clad ceramic substrate with single / double-sided copper cladding of the present invention during sintering;

[0023] Figure 2 is a schematic top view of the furnace bottom plate of the present invention;

[0024] In the figure: 1. Copper-clad ceramic substrate with single / double-sided copper cladding, 2. Backing plate, 3. Gasket, 4. Conveyor belt, 5. Furnace bottom plate, 6. Through-hole. Detailed Embodiments

[0025] The technical solutions of the present invention will be described in detail below with specific embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention rather than limiting the claims of the present invention.

[0026] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0027] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "provided with", "installed", "connected", and "communicated" should be understood in a broad sense. For example, it can be fixedly connected, detachably connected, or integrally connected; it can be directly communicated or indirectly communicated through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise specified, all are prior arts.

[0029] In order to solve the different degrees of oxidation problems that occur when the lead-free solder paste is used in the ceramic copper-clad substrate client in the background art, the inventor team carried out the following examples and comparative examples to find a solution to the copper surface oxidation problem.

[0030] In the prior art, the double-sided copper-clad ceramic substrate is made through the following steps:

[0031] Step S1, coat a layer of binder on one side of the cleaned ceramic substrate;

[0032] Step S2, place the cleaned copper foil on the ceramic substrate coated with the binder to ensure good contact between the copper foil and the surface of the ceramic substrate.

[0033] Step S3, press the stacked ceramic substrate and copper foil to firmly bond the ceramic substrate and the copper foil together to form a single-sided copper-clad copper-clad ceramic substrate.

[0034] Step S4, first sintering oxidation: the single-sided copper-clad copper-clad ceramic substrate is sintered through a sintering furnace by a conveyor belt, and after sintering, a single-sided copper-clad ceramic substrate is formed.

[0035] Step S5, coat a layer of binder on the other side of the ceramic substrate corresponding to the single-sided copper-clad ceramic substrate;

[0036] Step S6, place the cleaned copper foil on the single-sided copper-clad ceramic substrate coated with the binder to ensure good contact between the copper foil and the surface of the ceramic substrate.

[0037] Step S7, press the stacked single-sided copper-clad ceramic substrate and copper foil to firmly bond the single-sided copper-clad ceramic substrate and the copper foil together to form a double-sided copper-clad copper-clad ceramic substrate.

[0038] Step S8, second sintering oxidation: the double-sided copper-clad copper-clad ceramic substrate is sintered through a sintering furnace by a conveyor belt, and after sintering, a double-sided copper-clad ceramic substrate is formed.

[0039] In steps S4 and S8, the single-sided / double-sided copper-clad copper-clad ceramic substrates pass through three heating zones, four constant-temperature zones, and three cooling zones respectively. Among them, the three heating zones are 755°C - 765°C, 850°C - 860°C, and 1030°C - 1040°C in sequence, the temperature of the four constant-temperature zones is 1070°C - 1075°C, and the three cooling zones are 1025°C - 1035°C, 970°C - 980°C, and 920°C - 930°C in sequence. The passing time of the three heating zones is 9 - 13 min, the passing time of the four constant-temperature zones is 14 - 18 min, the passing time of the three cooling zones is 9 - 13 min, and the conveying speed of the conveyor belt is 80 - 85 mm / min.

[0040] In steps S4 and S8, the schematic structural diagram of the single-sided / double-sided copper-clad copper-clad ceramic substrate during sintering is as Figure 1 . Figure 1 In it, the single-sided / double-sided copper-clad copper-clad ceramic substrate 1 is placed on the backing plate 2, the backing plate 2 is placed on the spacer 3, the lower surface of the spacer 3 is in contact with the conveyor belt 4, and the furnace bottom plate 5 of the sintering furnace is located below the conveyor belt 4.

[0041] After sintering, the weight gain is measured. A weight gain of 15 - 30 mg is qualified, and less than 15 mg or more than 30 mg is unqualified. The product yield of the existing double-sided copper-clad ceramic substrate is 95%. Although the yield is good, the energy consumption is high. The formula for calculating the product yield is: Product yield = 100% * Number of qualified products / Total number of products.

[0042] In the prior art, the material of the spacer 3 is alumina, with a thickness of 5 - 10 mm, the backing plate 2 is a magnesium oxide foamed ceramic backing plate, the thickness of the backing plate 2 is 5 - 10 mm, the pore diameter is 0.08 - 3 mm, and the porosity is 25 - 30%. The conveyor belt 4 is a mesh conveyor belt.

[0043] In the following embodiments, the number of double-sided copper-clad ceramic substrates in each embodiment is the same as that of the prior art products.

[0044] Embodiment 1

[0045] A preparation method of a double-sided copper-clad ceramic substrate includes the following steps:

[0046] Step S1, coat a layer of binder on one side of the cleaned ceramic substrate;

[0047] Step S2, place the cleaned copper foil on the ceramic substrate coated with the binder to ensure good contact between the copper foil and the surface of the ceramic substrate.

[0048] Step S3, press the stacked ceramic substrate and copper foil to firmly bond the ceramic substrate and the copper foil together to form a single-sided copper-clad copper-clad ceramic substrate.

[0049] Step S4, First sintering and oxidation: The copper-clad ceramic substrate with single-sided copper cladding is sintered through a sintering furnace by a conveyor belt, and after sintering, a copper-clad ceramic substrate with single-sided copper cladding is formed.

[0050] Step S5, Coat a layer of binder on the other side of the ceramic substrate corresponding to the copper-clad ceramic substrate with single-sided copper cladding;

[0051] Step S6, Place the cleaned copper foil on the copper-clad ceramic substrate with single-sided copper cladding coated with the binder, ensuring good contact between the copper foil and the surface of the ceramic substrate.

[0052] Step S7, Press the stacked copper-clad ceramic substrate with single-sided copper cladding and the copper foil to firmly bond the copper-clad ceramic substrate with single-sided copper cladding and the copper foil together to form a copper-clad ceramic substrate with double-sided copper cladding.

[0053] Step S8, Second sintering and oxidation: The copper-clad ceramic substrate with double-sided copper cladding is sintered through a sintering furnace by a conveyor belt, and after sintering, a copper-clad ceramic substrate with double-sided copper cladding is formed.

[0054] In Step S4 and Step S8, the copper-clad ceramic substrates with single / double-sided copper cladding respectively pass through three heating zones, three constant-temperature zones and six cooling zones. Among them, the three heating zones are 480°C to 600°C, 600°C to 700°C, 650°C to 700°C in sequence, the temperature of the three constant-temperature zones is 850°C to 900°C, the six cooling zones are 650°C to 700°C, 640°C to 680°C, 620°C to 660°C, 600°C to 640°C, 580°C to 620°C, 500°C to 580°C in sequence, the passing time of the three heating zones is 9 - 13 min, the passing time of the three constant-temperature zones is 14 - 18 min, the passing time of the three cooling zones is 9 - 13 min, and the conveying speed of the conveyor belt is 80 - 85 mm / min.

[0055] In Step S4 and Step S8, the schematic structural diagram of the copper-clad ceramic substrate with single / double-sided copper cladding during sintering is as Figure 1 . Figure 1 In it, the copper-clad ceramic substrate 1 with single / double-sided copper cladding is placed on the backing plate 2, the backing plate 2 is placed on the spacer 3, the lower surface of the spacer 3 is in contact with the conveyor belt 4, and the furnace bottom plate 5 of the sintering furnace is located below the conveyor belt 4.

[0056] The product yield of the copper-clad ceramic substrate with double-sided copper cladding in this embodiment is 76%. Although the energy consumption is reduced, the product yield is decreased.

[0057] Embodiment 2

[0058] A preparation method of a copper-clad ceramic substrate with double-sided copper cladding, comprising the following steps:

[0059] Step S1, Coat a layer of binder on one side of the cleaned ceramic substrate;

[0060] Step S2: Place the cleaned copper foil on the ceramic substrate coated with the binder, ensuring good contact between the copper foil and the surface of the ceramic substrate.

[0061] Step S3: Press the stacked ceramic substrate and copper foil to firmly bond the ceramic substrate and the copper foil together, forming a copper-clad ceramic substrate with a single-sided copper coating.

[0062] Step S4: First sintering and oxidation: The copper-clad ceramic substrate with a single-sided copper coating passes through the sintering furnace via the conveyor belt for sintering, and after sintering, a copper-clad ceramic substrate with a single-sided copper coating is formed.

[0063] Step S5: Coat a layer of binder on the other side of the ceramic substrate corresponding to the copper-clad ceramic substrate with a single-sided copper coating.

[0064] Step S6: Place the cleaned copper foil on the copper-clad ceramic substrate with a single-sided copper coating coated with the binder, ensuring good contact between the copper foil and the surface of the ceramic substrate.

[0065] Step S7: Press the stacked copper-clad ceramic substrate with a single-sided copper coating and the copper foil to firmly bond the copper-clad ceramic substrate with a single-sided copper coating and the copper foil together, forming a copper-clad ceramic substrate with a double-sided copper coating.

[0066] Step S8: Second sintering and oxidation: The copper-clad ceramic substrate with a double-sided copper coating passes through the sintering furnace via the conveyor belt for sintering, and after sintering, a copper-clad ceramic substrate with a double-sided copper coating is formed.

[0067] In Step S4 and Step S8, the copper-clad ceramic substrates with single / double-sided copper coatings respectively pass through three heating zones, three constant-temperature zones and six cooling zones. Among them, the three heating zones are 480°C - 600°C, 600°C - 700°C, 650°C - 700°C in sequence, the temperature of the three constant-temperature zones is 750°C - 700°C, the six cooling zones are 650°C - 700°C, 640°C - 680°C, 620°C - 660°C, 600°C - 640°C, 580°C - 620°C, 500°C - 580°C in sequence. The passing time of the three heating zones is 9 - 13 min, the passing time of the three constant-temperature zones is 14 - 18 min, the passing time of the three cooling zones is 9 - 13 min, and the conveying speed of the conveyor belt is 80 - 85 mm / min.

[0068] In Step S4 and Step S8, the schematic structural diagram of the copper-clad ceramic substrate with single / double-sided copper coatings during sintering is as Figure 1 . Figure 1 shown in. In the figure, the copper-clad ceramic substrate 1 with single / double-sided copper coatings is placed on the backing plate 2, the backing plate 2 is placed on the spacer 3, the lower surface of the spacer 3 is in contact with the conveyor belt 4, and the furnace bottom plate 5 of the sintering furnace is located below the conveyor belt 4.

[0069] The product yield of the double-sided copper-clad ceramic substrate in this embodiment is 82%. Compared with Embodiment 1, although the product yield has increased, the product yield still needs to be improved.

[0070] Embodiment 3

[0071] A preparation method of a double-sided copper-clad ceramic substrate includes the following steps:

[0072] Step S1, coat a layer of binder on one side of a clean ceramic substrate.

[0073] Step S2, place a clean copper foil on the ceramic substrate coated with the binder, and ensure good contact between the copper foil and the surface of the ceramic substrate.

[0074] Step S3, press the stacked ceramic substrate and copper foil to firmly bond the ceramic substrate and the copper foil together to form a single-sided copper-clad copper-clad ceramic substrate.

[0075] Step S4, first sintering and oxidation: the single-sided copper-clad copper-clad ceramic substrate is sintered through a sintering furnace by a conveyor belt, and after sintering, a single-sided copper-clad ceramic substrate is formed.

[0076] Step S5, coat a layer of binder on the other side of the ceramic substrate corresponding to the single-sided copper-clad ceramic substrate.

[0077] Step S6, place a clean copper foil on the single-sided copper-clad ceramic substrate coated with the binder, and ensure good contact between the copper foil and the surface of the ceramic substrate.

[0078] Step S7, press the stacked single-sided copper-clad ceramic substrate and copper foil to firmly bond the single-sided copper-clad ceramic substrate and the copper foil together to form a double-sided copper-clad copper-clad ceramic substrate.

[0079] Step S8, second sintering and oxidation: the double-sided copper-clad copper-clad ceramic substrate is sintered through a sintering furnace by a conveyor belt, and after sintering, a double-sided copper-clad ceramic substrate is formed.

[0080] In Step S4 and Step S8, the single-sided / double-sided copper-clad copper-clad ceramic substrates respectively pass through three heating zones, three constant temperature zones and six cooling zones. Among them, the three heating zones are 480°C to 600°C, 600°C to 700°C, 650°C to 700°C in sequence, the temperature of the three constant temperature zones is 710°C to 830°C, the six cooling zones are 650°C to 700°C, 640°C to 680°C, 620°C to 660°C, 600°C to 640°C, 580°C to 620°C, 500°C to 580°C in sequence, the passing time of the three heating zones is 9 to 13 minutes, the passing time of the three constant temperature zones is 14 to 18 minutes, the passing time of the three cooling zones is 9 to 13 minutes, and the conveying speed of the conveyor belt is 80 to 85 mm / min.

[0081] In steps S4 and S8, the schematic structural diagram of the copper-clad ceramic substrate with single / double-sided copper cladding during sintering is as Figure 1 . Figure 1 As shown in, the copper-clad ceramic substrate 1 with single / double-sided copper cladding is placed on the backing plate 2, the backing plate 2 is placed on the spacer 3, the lower surface of the spacer 3 is in contact with the conveyor belt 4, and the furnace bottom plate 5 of the sintering furnace is located below the conveyor belt 4.

[0082] The product yield of the double-sided copper-clad ceramic substrate in this embodiment is 89%. Compared with Embodiment 2, although the product yield has increased, the product yield still needs to be improved.

[0083] Embodiment 4

[0084] A preparation method of a double-sided copper-clad ceramic substrate includes the following steps:

[0085] Step S1, coat a layer of binder on one side of the cleaned ceramic substrate;

[0086] Step S2, place the cleaned copper foil on the ceramic substrate coated with the binder to ensure good contact between the copper foil and the surface of the ceramic substrate.

[0087] Step S3, press the stacked ceramic substrate and copper foil to firmly bond the ceramic substrate and the copper foil together to form a single-sided copper-clad ceramic substrate.

[0088] Step S4, first sintering oxidation: The single-sided copper-clad ceramic substrate is sintered through a sintering furnace by a conveyor belt, and a single-sided copper-clad ceramic substrate is formed after sintering.

[0089] Step S5, coat a layer of binder on the other side of the ceramic substrate corresponding to the single-sided copper-clad ceramic substrate;

[0090] Step S6, place the cleaned copper foil on the single-sided copper-clad ceramic substrate coated with the binder to ensure good contact between the copper foil and the surface of the ceramic substrate.

[0091] Step S7, press the stacked single-sided copper-clad ceramic substrate and copper foil to firmly bond the single-sided copper-clad ceramic substrate and the copper foil together to form a double-sided copper-clad ceramic substrate.

[0092] Step S8, second sintering oxidation: The double-sided copper-clad ceramic substrate is sintered through a sintering furnace by a conveyor belt, and a double-sided copper-clad ceramic substrate is formed after sintering.

[0093] In steps S4 and S8, the single-sided / double-sided copper-clad ceramic substrates respectively pass through three heating zones, three constant-temperature zones, and six cooling zones. Among them, the three heating zones are successively 480°C to 600°C, 600°C to 700°C, and 650°C to 700°C; the temperatures of the three constant-temperature zones are 710°C to 830°C; the six cooling zones are successively 650°C to 700°C, 640°C to 680°C, 620°C to 660°C, 600°C to 640°C, 580°C to 620°C, and 500°C to 580°C. The passing time of the three heating zones is 9 to 13 minutes, the passing time of the three constant-temperature zones is 14 to 18 minutes, the passing time of the six cooling zones is 9 to 13 minutes, and the conveying speed of the conveyor belt is 80 to 85 mm / min.

[0094] In steps S4 and S8, a schematic structural state diagram of the single-sided / double-sided copper-clad ceramic substrate during sintering is as Figure 1 . Figure 1 shown. In the figure, the single-sided / double-sided copper-clad ceramic substrate 1 is placed on the backing plate 2, the backing plate 2 is placed on the spacer 3, the lower surface of the spacer 3 is in contact with the conveyor belt 4, and the furnace bottom plate 5 of the sintering furnace is located below the conveyor belt 4. The furnace bottom plate 5 of the sintering furnace is as Figure 2 . Figure 2 shown. In the figure, through holes 6 are uniformly formed on the furnace bottom plate 5, the aperture of the through holes 6 is 3 to 7 mm, and the hole opening rate is 30 to 35%.

[0095] The product yield of the double-sided copper-clad ceramic substrate in this embodiment is 96%.

[0096] By improving the sintering process, the present invention reduces energy consumption, but results in a decrease in the yield. Further, by improving the structure of the furnace bottom plate 5, the product yield is increased to not less than the level of the prior art.

[0097] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a double-sided copper-clad ceramic substrate, characterized in that: The following steps are involved: Step S1, coating a layer of adhesive on one side of a clean ceramic substrate; Step S2, placing the clean copper foil on a ceramic substrate coated with an adhesive; Step S3, pressing the stacked ceramic substrate and copper foil, and firmly bonding the ceramic substrate and the copper foil together to form a single-sided copper-clad ceramic substrate; Step S4, first sintering and oxidation: the copper-clad ceramic substrate with copper clad on one side is sintered through a sintering furnace via a conveyor belt to form a single-sided copper-clad ceramic substrate; Step S5, coating a layer of adhesive on the other side of the ceramic substrate corresponding to the single-sided copper-clad ceramic substrate; Step S6, placing the clean copper foil on the single-sided copper-clad ceramic substrate coated with an adhesive, ensuring that the copper foil is in good contact with the surface of the ceramic substrate; Step S7, pressing the stacked single-sided copper-clad ceramic substrate and the copper foil, and firmly bonding the single-sided copper-clad ceramic substrate and the copper foil together to form a double-sided copper-clad copper-clad ceramic substrate; Step S8, second sintering oxidation: the copper-clad ceramic substrate with copper clad on both sides is sintered through a sintering furnace via a conveyor belt to form a double-sided copper-clad ceramic substrate; In step S4 and step S8, during the sintering process, the copper-clad ceramic substrate is placed on a pad, the pad is placed on a gasket, the lower surface of the gasket is in contact with the conveyor belt, the furnace bottom plate of the sintering furnace is located below the conveyor belt, and through holes are evenly opened on the furnace bottom plate. The through hole diameter is 1 to 15 mm, and the opening rate is 20 to 50%.

2. The method for preparing a double-sided copper-clad ceramic substrate according to claim 1, characterized in that: In step S4 and step S8, the sintering process includes three heating zones, three constant temperature zones and six cooling zones in sequence, wherein the three heating zones are 480°C-600°C, 600°C-700°C and 650°C-700°C in sequence, the temperature of the three constant temperature zones is 850°C-900°C, the six cooling zones are 650°C-700°C, 640°C-680°C, 620°C-660°C, 600°C-640°C, 580°C-620°C and 500°C-580°C in sequence, the passing time of the three heating zones is 9-13 min, the passing time of the three constant temperature zones is 14-18 min, the passing time of the three cooling zones is 9-13 min, and the conveying rate of the conveyor belt is 80-85 mm / min.

3. The method for preparing a double-sided copper-clad ceramic substrate according to claim 1, characterized in that: In step S4 and step S8, the sintering process includes three heating zones, three constant temperature zones and six cooling zones in sequence, wherein the three heating zones are 480°C-600°C, 600°C-700°C and 650°C-700°C in sequence, the temperature of the three constant temperature zones is 750°C-700°C, the six cooling zones are 650°C-700°C, 640°C-680°C, 620°C-660°C, 600°C-640°C, 580°C-620°C and 500°C-580°C in sequence, the passing time of the three heating zones is 9-13 min, the passing time of the three constant temperature zones is 14-18 min, the passing time of the three cooling zones is 9-13 min, and the conveying rate of the conveyor belt is 80-85 mm / min.

4. The method for preparing a double-sided copper-clad ceramic substrate according to claim 1, characterized in that: In step S4 and step S8, the sintering process includes three heating zones, three constant temperature zones and six cooling zones in sequence, wherein the three heating zones are 480°C-600°C, 600°C-700°C and 650°C-700°C in sequence, the temperature of the three constant temperature zones is 710°C-830°C, the six cooling zones are 650°C-700°C, 640°C-680°C, 620°C-660°C, 600°C-640°C, 580°C-620°C and 500°C-580°C in sequence, the passing time of the three heating zones is 9-13 min, the passing time of the three constant temperature zones is 14-18 min, the passing time of the three cooling zones is 9-13 min, and the conveying rate of the conveyor belt is 80-85 mm / min.

5. The method for preparing a double-sided copper-clad ceramic substrate according to claim 1, characterized in that: The gasket material is aluminum oxide with a thickness of 5 to 10 mm; the pad is a magnesium oxide foamed ceramic pad with a thickness of 5 to 10 mm, a pore size of 0.08-3 mm, and a porosity of 25 to 30%; and the conveyor belt is a mesh conveyor belt.

6. The method for preparing a double-sided copper-clad ceramic substrate according to any one of claims 1 to 5, characterized in that: The through hole diameter is 3-7 mm, and the opening rate is 30-35%.

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