Method for reducing lumps on surface of copper-clad ceramic substrate product

Abstract

The invention discloses a method for reducing lumps on the surface of a copper-clad ceramic substrate product, which mainly comprises the following steps of: arranging a bubbling cleaning tank below a mesh belt, conveying compressed air into liquid to form eddy current, and cleaning the mesh belt under an oscillation effect; and meanwhile, after the net belt is cleaned, the sintering temperature of the next batch of DCB substrates is reduced, lumps on the surfaces of copper-clad ceramic substrate products are reduced, the yield of the products is improved, and the production cost is reduced.

Description

Technical Field

[0001] This application relates to the technical field of DCB substrate preparation, and specifically relates to a method for reducing surface bumps of copper-clad ceramic substrate products. Background Art

[0002] DCB technology uses the oxygen-containing eutectic liquid of copper to directly bond copper to 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.

[0003] Currently, the production of copper-clad ceramic substrates is basically sintered in two stages, that is, sinter one side first and then the other side. However, there are the following problems: When sintering products using a tunnel furnace, the metal dust in the furnace chamber will fly up onto the products, and after high-temperature sintering, protrusions and bumps will form on the product surface, resulting in an uneven copper layer surface of the DCB substrate product, affecting the electrical conductivity, increasing the thermal resistance. At the same time, the bumps can cause thermal stress concentration, increasing the risk of substrate cracking, reducing the product yield, and increasing production costs.

[0004] In view of this, this application is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for reducing surface bumps of copper-clad ceramic substrate products. Mainly, a bubbling cleaning tank is set below the mesh belt. At the same time, after the mesh belt is cleaned, the temperature during the sintering of the next batch of DCB substrates is reduced, reducing the surface bumps of the copper-clad ceramic substrate products, improving the product yield, and solving the problems existing in the prior art.

[0006] To solve the above technical problems, the present invention adopts the following solutions:

[0007] A method for reducing surface bumps of copper-clad ceramic substrate products includes the following steps:

[0008] Step 1: Add a cleaning tank below the mesh belt inside the tunnel furnace, so that the mesh belt above the cleaning tank is located inside the cleaning tank.

[0009] Step 2: If bumps are detected on the surface of the sintered copper-clad ceramic substrate, drive water to be added inside the cleaning tank to clean the mesh belt.

[0010] Step 3: After cleaning, reduce the temperature during the sintering of the next batch of ceramic substrates and copper foils.

[0011] Further preferably, a rotating roller is provided inside the cleaning tank, and the mesh belt located inside the cleaning tank is below the rotating roller.

[0012] Further preferably, the cleaning tank is a bubbling cleaning tank.

[0013] An inlet pipe, a drain pipe and a bubbling pipe are arranged in the bubbling cleaning tank. The bubbling pipe conveys compressed air into the liquid to form a vortex, which helps the gas to be evenly distributed in the pure water liquid, thereby oscillating the mesh belt inside the bubbling cleaning tank for cleaning, washing off the metal dust adhering to the mesh belt, reducing the protrusions on the surface of the copper-clad ceramic substrate after subsequent sintering, improving the product yield, and reducing the production cost.

[0014] Further preferably, the size of the bubbling cleaning tank is 1m×50cm×30cm.

[0015] Further preferably, pure water is used for cleaning.

[0016] Further preferably, the cleaning time in step two is 3 - 5h, and the bubbling pressure is 2 - 4MPa.

[0017] Further preferably, in step two and step three, the belt speed of the mesh belt is 100 - 150mm / min.

[0018] Further preferably, in step three, the temperature during the sintering of the ceramic substrate and the copper foil is 1066 - 1073°C.

[0019] Further preferably, when the ceramic substrate and the copper foil are sintered, they pass through four heating zones, four constant temperature zones and three cooling zones in sequence;

[0020] The four heating zones are sequentially set at temperatures between 600 - 700°C, 700 - 850°C, 850 - 960°C, and 850 - 1050°C;

[0021] The total length of the heating zones is 1000 - 1200mm; the time for the ceramic substrate and the copper foil to pass through the heating zones is 9 - 15min;

[0022] The passing times of the four heating zones are 3 - 4.5min, 3 - 4.5min, 3 - 4.5min, and 3 - 4.5min in sequence;

[0023] The four constant temperature zones are set at temperatures between 1066 - 1073°C; the total length of the constant temperature zones is 1300 - 1500mm; the time for the ceramic substrate and the copper foil to pass through the constant temperature zones is 14 - 18min;

[0024] The three cooling zones are sequentially set at temperatures between 1025 - 1035°C, 970 - 980°C, and 920 - 930°C;

[0025] The total length of the cooling zones is 1000 - 1100mm; the time for the ceramic substrate and the copper foil to pass through the cooling zones is 9 - 13min.

[0026] Further preferably, the sintering temperature in step three is 2-4 °C lower than that in step two.

[0027] The beneficial effects of the present invention are as follows: The present invention adopts a bubbling cleaning tank and a sintering temperature in the range of 1066-1073 °C. The bubbling tube in the bubbling cleaning tank conveys compressed air into the liquid to form a vortex. This vortex helps the gas to be evenly distributed in the pure water liquid, thereby oscillating the mesh belt inside the bubbling cleaning tank for cleaning, washing off the metal dust adhered to the mesh belt, and at the same time reducing the sintering temperature of the next batch, significantly reducing the bumps on the surface of the copper-clad ceramic substrate. Description of the Drawings

[0028] Figure 1 It is a physical diagram of the copper-clad ceramic substrate in Embodiment 1 of the present invention;

[0029] Figure 2 It is a physical diagram of the copper-clad ceramic substrate in Comparative Example 1 of the present invention;

[0030] Figure 3 It is a schematic assembly structure diagram of the mesh belt of the present invention in the bubbling cleaning tank. Detailed Embodiments

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0032] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0033] At the same time, it should be understood that for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships.

[0034] In addition, for the sake of clarity and conciseness, the descriptions of well-known structures, functions, and configurations may be omitted. Those of ordinary skill in the art will recognize that various changes and modifications can be made to the examples described herein without departing from the spirit and scope of the present disclosure.

[0035] The techniques, methods, and devices known to those of ordinary skill in the relevant fields may not be discussed in detail, but where appropriate, the said techniques, methods, and devices should be regarded as part of the authorization specification.

[0036] In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0037] This application provides an assembly structure. That is, a cleaning tank with dimensions of 1m×50cm×30cm is arranged below the mesh belt of the tunnel furnace, and rotating rollers are arranged in the cleaning tank, so that the mesh belt passes below these rotating rollers. When cleaning is required, the mesh belt below the rotating rollers is positioned below the liquid level, facilitating the cleaning of the mesh belt while it is being transported, and finally cleaning the metal dust that has fallen on the surface of the mesh belt inside the furnace, reducing the content of metal dust inside the furnace, and reducing the bumps formed on the surface of the copper-clad ceramic substrate during sintering. The mesh belt is assembled in the bubbling cleaning tank as Figure 3 shown. Among them, the operations of the water inlet pipe, the bubbling pipe in the bubbling cleaning tank, and the rotating rollers all belong to the prior art and will not be elaborated here.

[0038] Example 1

[0039] A method for reducing the bumps on the surface of copper-clad ceramic substrate products includes the following steps:

[0040] (1) If the camera in the equipment monitors or deems that bumps exist on the surface of this batch of sintered copper-clad ceramic substrates, it indicates that there is a relatively large amount of metal dust inside the tunnel furnace at this time. Transfer this batch of copper-clad ceramic substrates outside the tunnel furnace, open the water inlet pipe inside the bubbling cleaning tank, so that pure water is transported into the bubbling cleaning tank, make the mesh belt below the driving roller be positioned below the pure water liquid level, start the bubbling cleaning tank to work, with the bubbling pressure inside it being 2 - 4 MPa, the cleaning time being 3 - 5 h, and the belt speed of the mesh belt being 100 - 150 mm / min, so that all parts of the mesh belt are effectively cleaned.

[0041] (2) After cleaning is completed, close the bubbling cleaning tank, open the drain pipe, and drain the pure water inside the tank. Since there is a certain temperature at the bottom of the tunnel furnace, the mesh belt will be naturally dried during the transportation process. Place the next batch of ceramic substrates and copper foils above the mesh belt, with the sintering temperature being 1066 - 1073 °C and the belt speed of the mesh belt being 100 - 150 mm / min; when the ceramic substrates and copper foils are sintered, they sequentially pass through four heating zones, four constant temperature zones, and three cooling zones;

[0042] The four heating zones are sequentially set at temperatures between 600 - 700 °C, 700 - 850 °C, 850 - 960 °C, and 850 - 1050 °C;

[0043] The total length of the heating zones is 1000 - 1200 mm; the time for the ceramic substrates and copper foils to pass through the heating zones is 9 - 15 min;

[0044] The passing times of the four heating zones are 3 - 4.5 min, 3 - 4.5 min, 3 - 4.5 min, and 3 - 4.5 min in sequence;

[0045] The temperatures of the four constant temperature zones are set between 1066 - 1073 °C; the total length of the constant temperature zones is 1300 - 1500 mm; the passing time of the ceramic substrate and the copper foil through the constant temperature zones is 14 - 18 min;

[0046] The three cooling zones are in sequence with temperatures set between 1025 - 1035 °C, 970 - 980 °C, and 920 - 930 °C;

[0047] The total length of the cooling zones is 1000 - 1100 mm; the passing time of the ceramic substrate and the copper foil through the cooling zones is 9 - 13 min. The sintered copper - clad ceramic substrate is obtained, and the physical picture is referred to Figure 1 .

[0048] Example 2

[0049] A method for reducing the surface bumps of copper - clad ceramic substrate products, comprising the following steps:

[0050] (1) If the camera in the equipment monitors or deems that there are raised bumps on the surface of this batch of sintered copper - clad ceramic substrates, it indicates that the metal dust content inside the tunnel furnace is relatively high at this time. Transfer this batch of copper - clad ceramic substrates outside the tunnel furnace, open the water inlet pipe inside the bubbling cleaning tank, so that pure water is transported into the bubbling cleaning tank, make the mesh belt below the driving roller be under the pure water liquid level, start the bubbling cleaning tank to work, the bubbling pressure inside it is 2 - 4 MPa, the cleaning time is 3 - 5 h, and the belt speed of the mesh belt is 100 - 150 mm / min, so that each part of the mesh belt is effectively cleaned.

[0051] (2) After cleaning, close the bubbling cleaning tank, open the drain pipe, and drain the pure water inside the tank. Due to a certain temperature at the bottom of the tunnel furnace, the mesh belt will be naturally dried during the transmission process. Place the next batch of ceramic substrates and copper foils above the mesh belt, the sintering temperature is 1066 - 1073 °C, and the belt speed of the mesh belt is 100 - 150 mm / min; when the ceramic substrates and copper foils are sintered, they pass through four heating zones, four constant temperature zones, and three cooling zones in sequence;

[0052] The four heating zones are in sequence with temperatures set between 600 - 700 °C, 700 - 850 °C, 850 - 960 °C, and 850 - 1050 °C;

[0053] The total length of the heating zones is 1000 - 1200 mm; the passing time of the ceramic substrates and copper foils through the heating zones is 9 - 15 min;

[0054] The passing times of the four heating zones are 3 - 4.5 min, 3 - 4.5 min, 3 - 4.5 min, and 3 - 4.5 min in sequence;

[0055] The temperatures of the four constant temperature zones are set between 1074 - 1080 °C; the total length of the constant temperature zones is 1300 - 1500 mm; the passing time of the ceramic substrate and the copper foil through the constant temperature zones is 14 - 18 min;

[0056] The three cooling zones are as follows: the temperatures are set between 1025 - 1035 °C, 970 - 980 °C, and 920 - 930 °C in sequence;

[0057] The total length of the cooling zones is 1000 - 1100 mm; the passing time of the ceramic substrate and the copper foil through the cooling zones is 9 - 13 min. The sintered copper - clad ceramic substrate is obtained.

[0058] Comparative Example 1

[0059] Comparative Example 1 in this example is basically the same as Example 1, the difference is that Comparative Example 1 uses an ordinary cleaning tank, that is, there is no bubbling operation, and a sintered copper - clad ceramic substrate is obtained. The physical diagram is referred to Figure 2 。

[0060] Comparative Example 2

[0061] Comparative Example 1 in this example is basically the same as Example 2, the difference is that Comparative Example 1 uses an ordinary cleaning tank, that is, there is no bubbling operation, and a sintered copper - clad ceramic substrate is obtained.

[0062] Take the same number of sintered copper - clad ceramic substrates in Examples 1 - 2 and Comparative Examples 1 - 2, and observe the product yield of both sides of the copper - clad ceramic substrate manually. See Table 1 below:

[0063] Table 1 Comparison table of product yields of copper - clad ceramic substrates in examples and comparative examples

[0064] Sample Example 1 Example 2 Comparative Example 1 Comparative Example 2 Product yield 95％ 89％ 81％ 78％

[0065] As can be seen from Table 1, when using a bubbling cleaning tank and the sintering temperature is between 1066 - 1073 °C, the bubbling tube in the bubbling cleaning tank transports compressed air into the liquid to form a vortex. This vortex helps the gas to be evenly distributed in the pure water liquid, thereby oscillating the mesh belt inside the bubbling cleaning tank for cleaning, washing off the metal dust adhering to the mesh belt, and at the same time reducing the sintering temperature of the next batch, significantly reducing the bumps on the surface of the copper - clad ceramic substrate.

[0066] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as the content does not depart from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still belong to the scope of the technical solution of the present invention.

Claims

1. A method for reducing surface bumps on copper-clad ceramic substrate products, characterized in that: The following steps are involved: Step 1: Add a cleaning tank below the mesh belt inside the tunnel furnace so that the mesh belt above the cleaning tank is located inside the cleaning tank; Step 2: If it is detected that there are bumps on the surface of the sintered copper-clad ceramic substrate, water is added to the cleaning tank to clean the mesh belt; Step 3: After cleaning, lower the temperature for sintering the next batch of ceramic substrates and copper foil.

2. A method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 1, characterized in that: A rotating roller is arranged inside the cleaning tank, and the mesh belt located inside the cleaning tank is located below the rotating roller.

3. The method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 1, characterized in that: The cleaning tank is a bubbling cleaning tank.

4. A method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 3, characterized in that: The size of the bubbling cleaning tank is 1m×50cm×30cm.

5. The method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 3, characterized in that: Use pure water for cleaning.

6. A method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 5, characterized in that: The cleaning time in step 2 is 3 to 5 hours, and the bubbling pressure is 2 to 4 MPa.

7. The method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 5, characterized in that: In the steps 2 and 3, the belt speed of the mesh belt is 100-150 mm / min.

8. The method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 5, characterized in that: In step 3, the temperature during sintering of the ceramic substrate and the copper foil is 1066-1073°C.

9. A method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 8, characterized in that: When the ceramic substrate and the copper foil are sintered, they pass through four temperature rising zones, four constant temperature zones and three temperature falling zones in sequence; The four heating zones are set at 600-700°C, 700-850°C, 850-960°C, and 850-1050°C respectively; The total length of the heating zone is 1000-1200 mm; the time for the ceramic substrate and the copper foil to pass through the heating zone is 9-15 minutes; The transit time of the four heating zones is 3-4.5min, 3-4.5min, 3-4.5min, and 3-4.5min, respectively; The temperature of the four constant temperature zones is set between 1066 and 1073°C; the total length of the constant temperature zones is 1300 to 1500 mm; the time for the ceramic substrate and the copper foil to pass through the constant temperature zones is 14 to 18 minutes; The three cooling zones are set at temperatures between 1025-1035°C, 970-980°C, and 920-930°C; The total length of the cooling zone is 1000-1100 mm; the time for the ceramic substrate and the copper foil to pass through the cooling zone is 9-13 minutes.

10. The method for reducing surface bumps on a copper-clad ceramic substrate product according to claim 8, characterized in that: The sintering temperature in step three is 2-4° C. lower than the sintering temperature in step two.

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