Method for secondary sintering and flattening of ceramic substrate

Abstract

The invention discloses a method for secondary sintering and flattening of a ceramic substrate, which is characterized by comprising the following steps: step S1, classification: classifying the ceramic substrate according to the types of defects, and classifying the types of the defects into recesses, stripes and waves; when multiple defects exist, classifying according to main defects; s2, laminating and sintering: sequentially laminating a load bearing plate, a ceramic fire-resistant gasket, a ceramic substrate and a ceramic plate from bottom to top; then sintering to obtain a partially leveled or completely leveled ceramic substrate; in the lamination process, the ceramic substrates with the same type of defects are stacked together to be sintered. According to the method, after the defects of the ceramic substrates are classified, the ceramic substrates with the same defects are sintered together, so that defect transfer among different defects can be avoided, the qualification rate of the sintered ceramic substrates is remarkably improved, and the effects of simplifying the process and saving the cost can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic substrates, and in particular relates to a method for secondary sintering and flattening a ceramic substrate. Background Art

[0002] Ceramic substrate refers to a thin sheet of material made with ceramic material as the base through specific processes and technologies. Ceramics are widely used in electronics, optoelectronics, communications, aerospace and other fields due to their excellent properties such as high temperature stability, low thermal expansion coefficient, high mechanical strength, good corrosion resistance and insulation.

[0003] Currently, the commonly used method for making ceramic substrates is tape casting + high-temperature sintering. First, the powder is prepared into a slurry, and then the slurry is turned into a green body through tape casting. The obtained green body is then sintered at a high temperature to obtain a ceramic substrate.

[0004] The ceramic substrates obtained by tape casting + high temperature sintering method will inevitably have some defects, such as depressions, stripes and waves. However, the flatness and warpage of ceramic substrates are required to be high. Therefore, for substrates with defects, the general recycling plan of manufacturers is: re-grinding and re-casting + high temperature sintering. Such a recycling plan has a more complicated process and a higher recycling cost. Summary of the invention

[0005] The purpose of the present invention is to provide a method for secondary sintering and flattening a ceramic substrate with simple process and low recovery cost.

[0006] In a first aspect, the present invention provides a method for re-sintering and flattening a ceramic substrate, which adopts the following technical solution: A method for re-sintering and flattening a ceramic substrate, characterized in that it comprises the following steps: Step S1, classification: the ceramic substrate is classified according to the types of defects, and the types of defects are divided into depressions, stripes and waves; when there are multiple defects, they are classified according to the main defects; Step S2, lamination and sintering: lamination is performed in order from bottom to top, namely, a support plate, a ceramic refractory gasket, a ceramic substrate, and a ceramic plate; and then sintering is performed to obtain a partially or fully flattened ceramic substrate; during the lamination process, ceramic substrates with the same type of defects are stacked together and sintered.

[0007] Preferably, in the lamination process of step S2, the number of the support plate is 1; the number of the ceramic refractory gasket is 1; the number of the ceramic substrates is 10 to 20; and the number of the ceramic plates is 3 to 5.

[0008] Preferably, in step S2, the ceramic plate, the ceramic refractory gasket and the ceramic substrate are made of the same material.

[0009] Further preferably, the ceramic plate has a flatness greater than that of the ceramic substrate.

[0010] Preferably, in step S2, the sintering temperature is 1500-1800°C, the holding time is 18-24h, and the heating rate is 5-10°C / min.

[0011] Preferably, in step S2, the partially or fully flattened ceramic substrate is re-checked for parallelism, perpendicularity and warpage of the ceramic substrate. If the ceramic substrate meets the flatness requirements, it is a flattened ceramic substrate; if the ceramic substrate does not meet the flatness requirements, it is an unflattened ceramic substrate; the flatness requirements for the ceramic substrate are parallelism ≤ 0.8 mm, perpendicularity ≤ 0.8 mm, and warpage ≤ 1000 μm.

[0012] Preferably, in step S2, the flattened ceramic substrates are put into storage; for the ceramic substrates that are not flattened, steps S1 to S2 are repeated or the substrates are re-ground and then re-casted and sintered.

[0013] Beneficial effects of the present invention: The present invention classifies the defects of ceramic substrates and sinters ceramic substrates with the same defects together, which can avoid defect transmission between different defects, thereby significantly improving the qualified rate of ceramic substrates after sintering, thereby simplifying the process and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a picture of the wave defect on the ceramic substrate.

[0015] Figure 2 This is a picture of the depression defect on the ceramic substrate.

[0016] Figure 3 This is a picture of the stripe defect on the ceramic substrate.

[0017] Figure 4 It is a schematic diagram of the lamination of the secondary sintering of the ceramic substrate in the present invention. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments. Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0019] As mentioned above, in the first aspect, the present invention provides a method for secondary sintering and flattening a ceramic substrate, which adopts the following technical scheme: A method for re-sintering and flattening a ceramic substrate comprises the following steps: Step S1, classification: the ceramic substrate is classified according to the types of defects, and the types of defects are divided into depressions, stripes and waves; when there are multiple defects, they are classified according to the main defects; Step S2, lamination and sintering: lamination is performed in order from bottom to top, namely, a support plate, a ceramic refractory gasket, a ceramic substrate, and a ceramic plate; and then sintering is performed to obtain a partially or fully flattened ceramic substrate; during the lamination process, ceramic substrates with the same type of defects are stacked together and sintered.

[0020] The depressions, stripes and waves of the ceramic substrate can be seen Figures 1 to 3 Generally speaking, based on the uniformity of the casting slurry, ceramic substrates rarely have multiple defects after sintering. When multiple defects exist, they need to be classified according to their main defects.

[0021] During the secondary sintering process, the ceramic substrate will soften. If substrates with different defects are stacked together for sintering, the defects may be transferred due to the gravity of the ceramic plate. Therefore, in the present invention, defects are classified according to type, and defects of the same type are placed together for sintering, which can avoid the transfer of different defects between ceramic substrates during the secondary sintering process, thereby improving the qualified rate of ceramic substrates after the secondary sintering.

[0022] Preferably, in the lamination process of step S2, the number of the support plate is 1; the number of the ceramic refractory gasket is 1; the number of the ceramic substrates is 10 to 20; and the number of the ceramic plates is 3 to 5.

[0023] The bottom layer in the present invention is a support plate, which serves as a high temperature resistant carrier; the top layer is a refractory gasket, which can isolate the support plate from the ceramic substrate; the top layer is a ceramic plate, which is heavy and can flatten the softened ceramic substrate by gravity.

[0024] Preferably, in step S2, the ceramic plate, the ceramic refractory gasket and the ceramic substrate are made of the same material.

[0025] In the present invention, the material composition of the ceramic plate and the ceramic refractory gasket is controlled, so that the introduction of impurities into the ceramic substrate during the sintering process can be avoided.

[0026] Further preferably, the flatness of the ceramic plate needs to be greater than that of the ceramic substrate.

[0027] When the flatness of the ceramic plate in the present invention is greater than that of the ceramic substrate, defects of the ceramic substrate can be corrected better.

[0028] Preferably, in step S2, the sintering temperature is 1500-1800°C, the holding time is 18-24h, and the heating rate is 5-10°C / min.

[0029] The sintering temperature of the flattening in the present invention is slightly higher than the sintering temperature of the ceramic substrate tape casting preparation process, mainly to soften the ceramic substrate better, thereby achieving defect correction.

[0030] Preferably, in step S2, the partially or fully flattened ceramic substrate is re-inspected for parallelism, perpendicularity and warpage of the ceramic substrate. If the ceramic substrate meets the flatness requirements, it is a flattened ceramic substrate; if the ceramic substrate does not meet the flatness requirements, it is an unflattened ceramic substrate; the flatness requirements for the ceramic substrate are parallelism ≤ 0.8 mm, perpendicularity ≤ 0.8 mm, and warpage ≤ 1000 μm.

[0031] Preferably, in step S2, the flattened ceramic substrates are put into storage; for the ceramic substrates that are not flattened, steps S1 to S2 are repeated or the substrates are re-ground and then re-casted and sintered.

[0032] The lamination method of the present invention is as follows Figure 4 The specific sintering and flattening method can be seen in the embodiment. The ceramic substrate in the embodiment of the present invention is an alumina ceramic substrate.

[0033] In the art, the requirements for the flatness of ceramic substrates are as follows: parallelism ≤ 0.8 mm, verticality ≤ 0.8 mm, and warpage ≤ 1000 μm.

[0034] The components of the ceramic refractory backing plate and the ceramic plate are consistent with those of the ceramic substrate.

[0035] In the present invention, parallelism, verticality and warpage are tested by an image measuring instrument. The working principle of the image measuring instrument is as follows: the image measuring instrument uses surface light, contour light and coaxial light for illumination, and then captures images through a camera lens with a zoom objective lens. The images are then transmitted to a computer screen through an S terminal, and then the software commands obtain the required elements. The image generated on the display automatically measures the object to be measured, and the optical ruler is driven by the workbench to move in the X, Y and Z directions, and the multifunctional data processor performs data processing, and the measurement is completed through calculations by the software.

[0036] The ceramic plate with high flatness used in the embodiment of the present invention has a parallelism of ≤0.05 mm, a verticality of ≤0.05 mm, and a warpage of ≤50 μm.

[0037] The ceramic plate with poor flatness used in the embodiment of the present invention has a parallelism of >0.15 mm, a verticality of >0.15 mm, and a warpage of >150 μm.

[0038] Example 1 Step 1: Classify the three types of ceramic substrates with pits, stripes, and waves according to the type of defects, and place the defective ceramic substrates of the same type together. When there are multiple defects, classify them according to the main defects.

[0039] Step 2: Follow Figure 4 The specific number of stacking sheets is: one setter plate + one ceramic refractory gasket + 10 ceramic substrates (with the same defect type) + 3 ceramic plates (ceramic plates with higher flatness).

[0040] Step 3: After stacking, the temperature is raised to 1700°C at a heating rate of 7°C / min and sintered for 18 hours. After sintering, a sintered ceramic substrate is obtained.

[0041] Step 4: The sintered ceramic substrates are tested for parallelism, verticality and warpage, and qualified ceramic substrates and unqualified ceramic substrates are classified and counted, as shown in Table 1.

[0042] Comparative Example 1 The method is basically the same as Example 1, except that step 1 is omitted and defect classification is not performed; the defect types of the ceramic substrate in step 2 are not completely the same; and three sets of data are obtained in parallel. The specific data results can be seen in Table 1.

[0043] Example 2 It is basically the same as Example 1, except that there are 15 ceramic substrates in step 2, and the rest remain unchanged.

[0044] Example 3 It is basically the same as Example 1, except that there are 20 ceramic substrates in step 2, and the rest remain unchanged.

[0045] Example 4 It is basically the same as Example 1, except that there are 4 ceramic plates in step 2, and the rest remain unchanged.

[0046] Example 5 It is basically the same as Example 2, except that there are 4 ceramic plates in step 2, and the rest remain unchanged.

[0047] Example 6 It is basically the same as Example 3, except that there are 4 ceramic plates in step 2, and the rest remain unchanged.

[0048] Example 7 It is basically the same as Example 1, except that there are 5 ceramic plates in step 2, and the rest remain unchanged.

[0049] Example 8 It is basically the same as Example 2, except that there are 5 ceramic plates in step 2, and the rest remain unchanged.

[0050] Example 9 It is basically the same as Example 3, except that there are 5 ceramic plates in step 2, and the rest remain unchanged.

[0051] Example 10 The method is basically the same as Example 1, except that a ceramic plate with poor flatness is used in step 2.

[0052] Embodiment 11 It is basically the same as Example 8, except that the sintering process is: heating to 1500°C at a heating rate of 5°C / min and sintering for 24 hours at this temperature, and after sintering, a sintered ceramic substrate is obtained.

[0053] Example 12 It is basically the same as Example 8, except that the sintering process is: heating to 1800°C at a heating rate of 10°C / min and sintering for 18 hours at this temperature, and after sintering, a sintered ceramic substrate is obtained.

[0054] The specific data and flatness of the sintered and flattened ceramic substrate in the embodiment can be seen in Table 1.

[0055] Table 1 Comparison of the data of Example 1 and Comparative Example 1 shows that after the ceramic substrates are classified according to the types of defects, the effect of secondary sintering and leveling is significantly improved.

[0056] In Examples 1 to 3, the number of ceramic substrates added during the lamination process is different. From the comparison of the data of the three, the more ceramic substrates are added, the higher the efficiency will be; however, the average parallelism, verticality and warpage of the qualified ceramic substrates will be improved to a certain extent.

[0057] Embodiment 1, embodiment 4 and embodiment 7 mainly increase the number of ceramic plates during the lamination process; as the number of ceramic plates increases, the weight will increase, the qualified rate of ceramic plates will increase, and the average parallelism, verticality and warpage of qualified ceramic substrates will be further reduced.

[0058] In the lamination process of Example 2, Example 5 and Example 8, the number of ceramic plates is also increased; the changing rules of the effects are basically the same as those of Example 1, Example 4 and Example 7.

[0059] In the lamination process of Example 3, Example 6 and Example 9, the number of ceramic plates is also increased; the changing rules of the effects are basically the same as those of Example 1, Example 4 and Example 7.

[0060] Comparison of the data of Example 1 and Example 10 shows that the flatness of the ceramic plate is higher, and the sintering flattening effect can also be improved.

[0061] The main difference between Example 8, Example 11 and Example 12 is the sintering process parameters. Overall, the sintering process in Example 12 is the best.

[0062] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for re-sintering and flattening a ceramic substrate, characterized in that: The following steps are involved: Step S1, classification: the ceramic substrate is classified according to the types of defects, and the types of defects are divided into depressions, stripes and waves; when there are multiple defects, they are classified according to the main defects; Step S2, lamination and sintering: lamination is performed in order from bottom to top, namely, a support plate, a ceramic refractory gasket, a ceramic substrate, and a ceramic plate; and then sintering is performed to obtain a partially or fully flattened ceramic substrate; during the lamination process, ceramic substrates with the same type of defects are stacked together and sintered.

2. The method for re-sintering and flattening a ceramic substrate according to claim 1, characterized in that: In the stacking of step S2, the number of the support plate is 1; the number of the ceramic refractory gasket is 1.

3. The method for re-sintering and flattening a ceramic substrate according to claim 1, characterized in that: In the stacking of the step S2, there are 10 to 20 ceramic substrates and 3 to 5 ceramic plates.

4. The method for re-sintering and flattening a ceramic substrate according to claim 1, characterized in that: In step S2, the ceramic plate, the ceramic refractory gasket and the ceramic substrate are made of the same material.

5. The method for re-sintering and flattening a ceramic substrate according to claim 1, characterized in that: The flatness of the ceramic plate is greater than that of the ceramic substrate.

6. The method for re-sintering and flattening a ceramic substrate according to claim 1, characterized in that: In the step S2, the sintering temperature is 1500-1800°C, the holding time is 18-24h, and the heating rate is 5-10°C / min.

7. The method for re-sintering and flattening a ceramic substrate according to claim 1, characterized in that: In step S2, the partially or fully flattened ceramic substrate is re-checked for parallelism, verticality and warpage of the ceramic substrate. If the ceramic substrate meets the flatness requirements, it is a flattened ceramic substrate; if the ceramic substrate does not meet the flatness requirements, it is an unflattened ceramic substrate; the flatness requirements for the ceramic substrate are parallelism ≤ 0.8 mm, verticality ≤ 0.8 mm, and warpage ≤ 1000 μm.

8. The method for re-sintering and flattening a ceramic substrate according to claim 1 or 7, characterized in that: In step S2, the flattened ceramic substrates are put into storage; for the unflattened ceramic substrates, steps S1 to S2 are repeated or the substrates are re-ground and powdered before being cast and sintered again.

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