Ceramic wedge and its preparation method and application

Abstract

The application discloses a ceramic wedge and a preparation method and application thereof, and the preparation method comprises the following steps: S1: ceramic slurry is made into a ceramic wedge finished product; the ceramic slurry comprises ZTA powder; the ZTA powder comprises the following raw materials in percentage by mass: 60-95% of aluminum oxide and 5-40% of zirconium oxide; S2: the ceramic wedge finished product is heat treated to adjust the precipitation rate of aluminum oxide or zirconium oxide in the surface layer, and the ceramic wedge is prepared. The preparation method in the application performs surface heat treatment on the ceramic wedge finished product, the content of aluminum oxide and zirconium oxide in the surface layer of the ceramic wedge can be adjusted by adjusting the temperature, pressure and time during heat treatment, so that the hardness of the working surface of the ceramic wedge can be adjusted, and the hardness of the ceramic wedge can be selectively adjusted according to different use requirements.

Description

Technical Field

[0001] This invention belongs to the field of cleaver technology, specifically relating to a ceramic cleaver, its preparation method, and its application. Background Technology

[0002] Ceramic wedges are precision ceramic parts that serve as welding tools in the wire bonding process and are indispensable in the field of microelectronic device packaging. The key dimensions of the complex internal structure of ceramic wedges and their mechanical properties also play a decisive role in the quality of electronic packaging.

[0003] Ceramic cleavers are generally manufactured using injection molding. A suitable mold is used as a carrier to feed ceramic material into the material, and the green body is formed through injection molding. After debinding and sintering, further finishing processes yield the finished cleaver. However, to obtain ceramic cleavers with higher molding precision and greater plasticity, ceramic photopolymerization technology combined with 3D printing technology can avoid the expensive, standardized molds used in injection molding. In practical applications, different applications have varying requirements for the mechanical properties of the working surface (T-surface, located at the tip of the cleaver head). The compatibility of hardness directly determines the service life of the cleaver and the quality of the weld lines. This is especially true for base plate coatings made of different materials, such as copper, silver, nickel, and gold, which have varying degrees of hardness. Harder metals are better suited to "softer cleavers" (lower hardness) for weld lines, while softer metals are better suited to "harder cleavers" (higher hardness) for weld lines. In existing technologies, the hardness and fracture toughness of the ceramic cutting tool are generally changed by adjusting the ceramic material formula. However, the T-surface properties are greatly affected by the sintering process and are difficult to control accurately and effectively. While adding a coating to the T-surface can precisely control the hardness, in practice, the inner hole of the cutting tool is simultaneously buried during the coating process, making it difficult to completely avoid the influence of the coating. Furthermore, the coating on the T-surface is only physically bonded to the ceramic substrate. Due to the large difference in their coefficients of thermal expansion, the bonding force between them is poor, and the coating is prone to peeling off with increasing use time, which greatly reduces the service life and yield of the ceramic cutting tool. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a method for preparing a ceramic chopping knife.

[0005] The second objective of this invention is to provide a ceramic chopping knife.

[0006] The third objective of this invention is to provide an application of a ceramic chopping tool in the field of device packaging.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of this invention provides a method for preparing a ceramic chopping knife, comprising the following steps:

[0009] S1: The ceramic slurry is made into a finished ceramic cleaver; the ceramic slurry includes ZTA powder; the ZTA powder includes the following raw materials in mass percentage: 60-95% alumina and 5-40% zirconium oxide;

[0010] S2: The ceramic chopping knife is heat-treated to adjust the precipitation rate of alumina or zirconium oxide in its surface layer, thereby obtaining the ceramic chopping knife.

[0011] Preferably, in the surface layer of the ceramic chopping knife, the precipitation rate of alumina is 1-70% or the precipitation rate of zirconium oxide is 10-300%.

[0012] Preferably, in the surface layer of the ceramic chopping knife, the precipitation rate of alumina is 7-40% or the precipitation rate of zirconium oxide is 20-100%.

[0013] The formula for calculating the precipitation rate is:

[0014] Precipitation rate = (content after heat treatment - content before heat treatment) / content before heat treatment. For example: the precipitation rate of alumina is (alumina content in the surface layer of the ceramic cleaver measured after heat treatment - alumina content in the surface layer measured before heat treatment) / alumina content measured before heat treatment.

[0015] The above precipitation rate ratio is calculated based on the ratio of alumina to zirconium oxide in the ZTA (zirconia toughened alumina, hereinafter referred to as ZTA) powder actually used. The precipitation rate range of zirconium oxide and alumina can be calculated based on the actual ZTA powder formulation and is not limited to the above-mentioned range. For example, if the ZTA contains 5 wt% zirconium oxide and 95 wt% alumina, the zirconium oxide precipitation rate can exceed 100% under given heat treatment conditions.

[0016] The principle of adjusting the hardness of the heat-treated ceramic chopping knife of this invention is as follows: The ZTA powder in this invention contains two components: alumina and zirconium oxide. Under high temperature and high pressure, the zirconium oxide component in the ZTA powder undergoes a phase transformation, changing from a tetragonal phase to a monoclinic phase. During the phase transformation, the volume of the grains also increases. The zirconium oxide grains closer to the surface are more significantly affected by pressure. Under the pressure, in order to reduce the energy generated by the volume increase due to the phase transformation, the zirconium oxide grains will spontaneously migrate towards the surface. Based on the principle of minimum energy, precipitation is preferentially carried out on the surface, ultimately forming a morphology of zirconium oxide enriched on the surface. The material itself has a lower hardness than alumina (alumina hardness is 1400-1550 HV1, alumina hardness is 1900-2000 HV1), thus achieving the adjustment of the low surface hardness performance. Correspondingly, under high temperature and negative pressure (vacuum) conditions, zirconia grains tend to transform from monoclinic phase to tetragonal phase, and the grain volume shrinks accordingly. To reduce surface energy and ensure stability, alumina tends to accumulate on the surface. There is no need to change its formula or add an extra coating. The higher the alumina content, the higher the hardness. That is, by controlling the temperature, pressure and time, the controllable adjustment of the high surface hardness of the cleaver can be achieved.

[0017] This invention utilizes the characteristics of ZTA powder material and controls the precipitation rate of alumina or zirconium oxide on the surface of ceramic chopping tools by controlling the temperature and other related parameters of heat treatment. It can prepare ceramic chopping tool surfaces with different hardness according to different needs, thereby obtaining ceramic chopping tools with high adaptability, precise control of mechanical properties and long service life.

[0018] To adjust the hardness of ceramic wedges, it is necessary to control the precipitation of alumina and zirconium oxide on the surface. When a ceramic wedge A with high surface hardness is desired (hereinafter referred to as ceramic wedge A as a high-hardness wedge), it is necessary to control the precipitation of alumina to a large extent on the surface of the ceramic wedge. If the heat treatment temperature is too low or the pressure is too high, the migration rate of alumina will be too slow, or the heat treatment time will be too short, and the effect of high-level alumina precipitation will not be achieved, thus failing to achieve controllable improvement in hardness. On the other hand, if the heat treatment temperature is too high or the heat treatment time is too long, alumina grains are prone to abnormal growth, resulting in a dispersed alumina grain structure and uneven grain size distribution, even after complete alumina precipitation. Its hardness actually shows a decreasing trend, which will significantly reduce properties such as bending strength and fracture toughness. Abnormal growth is serious and may even cause defects, affecting the overall performance of the ceramic wedge. When it is necessary to obtain a ceramic wedge B with low surface hardness (hereinafter, ceramic wedge B is used as a low-hardness wedge), it is necessary to control the precipitation of zirconia on the surface of the ceramic wedge to a large extent. If the heat treatment temperature is too low, the migration rate of zirconia is too slow, and zirconia cannot be completely precipitated within the specified time. On the other hand, excessively high temperature or excessively low pressure will cause excessive growth of zirconia grains, affecting the overall performance. When the pressure is too high, the residual internal stress inside the ceramic wedge is too large, which is prone to breakage and other adverse consequences during subsequent use.

[0019] Preferably, step S2 involves heat-treating the finished ceramic chopping knife to precipitate alumina on its surface at a temperature of 1400–1700°C and a pressure not exceeding 10 Pa. More preferably, step S2 involves heat-treating the finished ceramic chopping knife to precipitate alumina on its surface at a temperature of 1500–1600°C and a pressure of 10 Pa. -3 ~10 -2 Pa. To obtain ceramic chopping tools A with high surface hardness, it is necessary to control the content of alumina precipitated on the surface of the ceramic chopping tool.

[0020] Preferably, step S2 involves heat-treating the finished ceramic chopping knife to precipitate zirconium oxide on its surface at a temperature of 1300–1650°C and a pressure of 130–200 MPa. More preferably, step S2 involves heat-treating the finished ceramic chopping knife to precipitate zirconium oxide on its surface at a temperature of 1400–1500°C and a pressure of 150–180 MPa. To obtain a ceramic chopping knife B with low surface hardness, it is necessary to control the zirconium oxide content precipitated on the surface of the ceramic chopping knife.

[0021] Preferably, the heat treatment time is 30 to 240 minutes; more preferably, the heat treatment time is 100 to 200 minutes.

[0022] Preferably, the ceramic slurry comprises the following raw materials in weight percentages: 55-65% ZTA powder, 30-40% oligomer, 0.01-1% light absorber, 0.1-10% photoinitiator, and 0.1-5% dispersant.

[0023] Preferably, the oligomer is selected from polyurethane acrylates.

[0024] Preferably, the light absorber is selected from Sudan III.

[0025] Preferably, the photoinitiator is selected from phenylbis(2,4,6-trimethylformyl)phosphine oxide.

[0026] Preferably, the dispersant is selected from BYK-111.

[0027] Preferably, step S1 involves: forming a ceramic cleaver blank from the ceramic slurry, then sintering the ceramic cleaver blank after removing the binder, and finally finishing it into a finished ceramic cleaver. More preferably, step S1 involves: printing and curing the ceramic slurry into a ceramic cleaver blank using a photopolymerization 3D printing method, then sintering the ceramic cleaver blank after removing the binder, and finally finishing it into a finished ceramic cleaver. This invention uses a photopolymerization 3D printing method to obtain ceramic cleavers with higher molding precision and greater plasticity, avoiding the expensive and standardized molds used in injection molding. Furthermore, the dimensions of ceramic cleavers produced using the photopolymerization 3D printing method are easier to adjust, and the internal structure of the ceramic cleaver has better uniformity. The purpose of the finishing step is to further grind it to the required precision in terms of outer diameter, length, and conical surface dimensions to obtain the finished ceramic cleaver.

[0028] Preferably, the debinding and sintering step employs at least one of the following methods: atmospheric pressure sintering, vacuum sintering, hot pressing sintering, and hot isostatic pressing sintering.

[0029] A second aspect of the present invention provides a ceramic chopping knife, which is prepared using the preparation method provided in the first aspect of the present invention.

[0030] Preferably, the surface layer of the ceramic chopping knife after heat treatment has an alumina content of 75-98% by mass, with the balance being zirconium oxide.

[0031] Preferably, the zirconium oxide content on the surface of the ceramic cleaver after heat treatment is 36-60% by mass, with the balance being alumina.

[0032] The third aspect of the present invention provides the application of the ceramic chopping tool provided in the first aspect of the present invention in the field of device packaging.

[0033] The beneficial effects of this invention are as follows: The preparation method of this invention involves surface heat treatment of the finished ceramic wedge. By adjusting the temperature, pressure, and time during heat treatment, the content of alumina and zirconium oxide in the surface layer of the ceramic wedge can be controlled, thereby adjusting the hardness of the working surface of the ceramic wedge. This allows for selective adjustment of the hardness of the ceramic wedge according to different usage requirements. Compared with existing technologies that adjust hardness by changing the raw material formula or adding a coating, this invention can obtain ceramic wedges with different degrees of hardness performance without using complex coating techniques, while maintaining the original formula, by controlling the precipitation rate of alumina and zirconium oxide on the surface layer. This makes them suitable for different application scenarios and has significant practical implications for extending the service life of the wedge and ensuring the quality of wire bonding. Attached Figure Description

[0034] Figure 1 This is an electron microscope image of the surface of the ceramic chopping tool in Example 3;

[0035] Figure 2 This is an electron microscope image of the surface of the ceramic chopping knife in Comparative Example 3. Detailed Implementation

[0036] The following examples provide a more detailed description of the specific implementation of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are methods that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0037] Example 1

[0038] The ceramic chopping knife in this example was prepared using the following raw materials in the indicated weight percentages: 60 wt% ZTA powder, 36.4 wt% polyurethane acrylate, 0.1 wt% Sudan III, 2 wt% phenyl bis(2,4,6-trimethylformyl)phosphine oxide, and 1.5 wt% BYK-111 dispersant. In the ZTA powder, the mass percentage of alumina was 70 wt% and the mass percentage of zirconium oxide was 30 wt%.

[0039] The ceramic chopping knife in this example was prepared using the following method:

[0040] S1: ZTA powder, polyurethane acrylate, Sudan III, phenyl bis(2,4,6-trimethylformyl)phosphine oxide, and BYK-111 dispersant were mixed and ball-milled to prepare a ceramic slurry. Then, the ceramic slurry was printed and cured using a photopolymerization 3D printing method to prepare an integrated ceramic chopping blade blank.

[0041] S2: The ceramic chopping blank obtained in step S1 is subjected to debinding and sintering treatment. The debinding temperature is 600℃, the debinding time is 48h, the sintering temperature is 1500℃, and the holding time is 2h. After sintering is completed, it is further ground to the required precision of the outer diameter, length and conical surface size of the finished ceramic chopping blank.

[0042] S3: Perform surface heat treatment on the ceramic chopping knife product obtained in step S2. The heat treatment temperature is 1400℃ and the heat treatment pressure is 10. -2 Pa, heat treatment time of 30 min, thereby adjusting the composition ratio of the surface layer to obtain the ceramic chopping knife in this example with the required hardness.

[0043] Examples 2-21

[0044] The raw materials used to prepare the ceramic chopping knives in Examples 2 to 21 are the same as those in Example 1.

[0045] Compared with the preparation method of the ceramic cleaver in Example 1, the preparation methods of the ceramic cleavers in Examples 2-21 differ in that at least one of the heat treatment parameters—temperature, time, and pressure—is different. The specific heat treatment temperatures, times, and pressures for the surface heat treatment of the ceramic cleavers in Examples 2-21 are recorded in Table 1.

[0046] Comparative Examples 1-12

[0047] The raw materials used to prepare the ceramic chopping knives in Comparative Examples 1 to 12 were the same as those in Example 1.

[0048] Compared with the preparation method of the ceramic chopping knife in Example 1, the preparation methods of the ceramic chopping knives in Comparative Examples 1 to 12 differ in that at least one of the heat treatment parameters—temperature, time, and pressure—is different. The specific heat treatment temperature, time, and pressure for the surface heat treatment of the ceramic chopping knives in Comparative Examples 1 to 12 are recorded in Table 1.

[0049] Table 1. Temperature, pressure, and time parameters for the surface heat treatment of the ceramic chopping tools in Examples 1-21 and Comparative Examples 1-12.

[0050]

[0051]

[0052] In Table 1, Examples 1-12 are for preparing ceramic chopping knives A, and Comparative Examples 1-3, 5-6 and 10 are set as control groups for Examples 1-12; Examples 13-21 are for preparing ceramic chopping knives B, and Comparative Examples 7-9 and 11 are set as control groups for Examples 13-21; Comparative Example 4 is a control group without external pressure (atmospheric pressure) during heat treatment; Comparative Example 12 is a blank control group without any treatment (room temperature 25°C, atmospheric pressure).

[0053] Performance testing:

[0054] The surface phase ratio and nano-indentation hardness of the ceramic chopping tools in Examples 1-21 and Comparative Examples 1-12 were tested respectively. The specific test methods are as follows:

[0055] (1) Surface phase ratio: The surface grain morphology image was captured using the secondary electron mode of SEM. Then, the grain area ratio of zirconium oxide and alumina was calculated using ImageJ image area processing software. The grains were approximated as spherical, and the phase composition content (mass ratio) of the ceramic wedge surface could be calculated by volume ratio. The precipitation rate of the surface phase was calculated according to the following formula:

[0056] Surface alumina precipitation ratio = (Surface alumina content after heat treatment - Original surface alumina content) / Original surface alumina content;

[0057] The proportion of precipitated zirconium oxide on the surface = (zirconia content on the surface after heat treatment - original zirconium oxide content on the surface) / original zirconium oxide content on the surface.

[0058] (2) Nanoindentation hardness: The hardness of the T-face of the cleaver was tested using a nanoindenter. Five points were randomly selected for each sample for testing, and the average value of the data was taken.

[0059] Table 2 shows the surface phase ratio and nanoindentation hardness data of the ceramic chopping knives in Examples 1-21 and Comparative Examples 1-12, which were measured according to the above test method.

[0060] Table 2. Surface phase ratios and nanoindentation hardness data of the ceramic chopping tools in each embodiment and comparative example.

[0061]

[0062]

[0063] As shown in Tables 1 and 2, compared with Examples 1-12, the amount of alumina precipitation in Comparative Examples 1 and 4, using lower heat treatment temperatures or higher pressures, was extremely small and did not play a role in regulating the alumina content on the surface of the ceramic chopping tools. Electron micrographs of the surface of the ceramic chopping tools in Example 3 and Comparative Example 3 were obtained, and the specific test results are as follows: Figure 1 and Figure 2 As shown, where, Figure 1 and Figure 2 These are electron microscope (EM) images of the ceramic chopping tools from Example 3 and Comparative Example 3, respectively; Figures 1-2 It can be seen that the ceramic wedge in Example 3 exhibits normal grain growth on its surface, with uniform grain size and distribution. In contrast, the ceramic wedge in Comparative Example 3 shows abnormal grain growth and excessively large grain size. According to Tables 1-2, when the heat treatment temperature is too high (Comparative Example 3) or the heat treatment time is too long (Comparative Example 6), the alumina content on the surface of the ceramic wedge can reach the required percentage (precipitation rate of 40%). However, the abnormal grain growth and excessively large size result in a dispersed structure and uneven grain size distribution. With a large amount of alumina precipitation, the hardness may further decrease, leading to a significant reduction in bending strength and fracture toughness. For example, when using a universal material testing instrument with the three-point bending method to test the bending strength, with an alumina content of 98% after precipitation, the bending strength values ​​measured in Comparative Example 3 and Comparative Example 6 are 534 MPa and 526 MPa, respectively, significantly lower than that of Example 10 (675 MPa). This can even cause defects and affect the overall performance of the ceramic wedge.

[0064] Examples 7-11 were designed with different heat treatment pressures. Referring to Tables 1-2, it can be seen that the closer the heat treatment pressure is to 0, the more alumina is precipitated after heat treatment, and the higher the hardness. However, comparing Example 5 with Comparative Example 4, using atmospheric pressure, which is higher than atmospheric pressure, does not effectively regulate alumina precipitation.

[0065] Examples 13-19 were set with different heat treatment temperatures and pressures, and Examples 20-21 were set with different heat treatment times. Referring to Tables 1-2, a comparison of Examples 15-16 and Comparative Examples 7-8 shows that, under the same heat treatment pressure and time, when the heat treatment temperature is too low, less zirconium oxide precipitates, failing to achieve a regulating effect. When the heat treatment temperature is too high, zirconium oxide precipitates completely, but at this point, grain growth is excessive, with abnormal grain growth and excessively large sizes, further reducing hardness and affecting the overall quality of the cleaver. A comparison of Examples 15 and 18 with Comparative Example 9 shows that, under the same heat treatment temperature and time, when the heat treatment pressure is too low, it has a significant impact on grain growth, increasing grain disorder and thus greatly reducing the cleaver's performance. Comparative Examples 10 and 11, treated at room temperature, did not achieve a regulating effect on surface content simply by changing the pressure. Comparative Example 12 served as a blank control group under normal temperature and pressure (atmospheric pressure).

[0066] The ceramic chopping blade A prepared in Examples 1-21 of this invention has a hardness of 21-34 GPa; the ceramic chopping blade B has a hardness of 14-17 GPa. These hardness data are based on specific contents of alumina and zirconium oxide in the ZTA powder used in these examples and are merely examples, not representing the maximum or minimum hardness range achievable by the ceramic chopping blades prepared according to the technical solutions of this invention. Adjusting the contents of alumina and zirconium oxide in the ZTA powder will change the hardness of the ceramic chopping blade. Therefore, the ceramic chopping blade of this invention can be controllably adjusted according to the different hardness requirements of the application. For example, the hardness can be initially adjusted by adjusting the contents of alumina and zirconium oxide in the ZTA powder, and then finely adjusted by controlling the temperature, pressure, and time of the heat treatment, thereby achieving controllable adjustment of the ceramic chopping blade's hardness.

[0067] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing a ceramic chopping knife, characterized in that: Includes the following steps: S1: The ceramic slurry is processed into a finished ceramic cleaver; the ceramic slurry includes ZTA powder; the ZTA powder comprises the following raw materials by mass percentage: 60-95% alumina and 5-40% zirconium oxide; S2: The ceramic chopping knife is heat-treated to adjust the precipitation rate of alumina or zirconium oxide in its surface layer, thereby obtaining the ceramic chopping knife; Step S2 specifically involves: heat-treating the finished ceramic chopping knife to precipitate alumina on the surface of the ceramic chopping knife, wherein the heat treatment temperature is 1400~1700℃ and the heat treatment pressure is not higher than 10Pa; or, heat-treating the finished ceramic chopping knife to precipitate zirconium oxide on the surface of the ceramic chopping knife, wherein the heat treatment temperature is 1300~1650℃ and the heat treatment pressure is 130~200MPa. The heat treatment time is 30~240 min.

2. The method for preparing the ceramic chopping knife according to claim 1, characterized in that: Step S2 involves heat-treating the finished ceramic chopping knife to precipitate alumina on its surface. The heat treatment temperature is 1500-1600℃, and the heat treatment pressure is 10... -3 ~10 -2 Pa.

3. The method for preparing the ceramic chopping knife according to claim 1, characterized in that: In the surface layer of the ceramic chopping knife, the precipitation rate of alumina is 1~70% or the precipitation rate of zirconium oxide is 10~100%.

4. The method for preparing the ceramic chopping knife according to claim 1, characterized in that: In the surface layer of the ceramic chopping knife, the precipitation rate of alumina is 7-40% or the precipitation rate of zirconium oxide is 20-100%.

5. The method for preparing the ceramic chopping knife according to claim 1, characterized in that: Step S2 is as follows: heat-treating the finished ceramic chopping knife to precipitate zirconium oxide on the surface of the ceramic chopping knife. The heat treatment temperature is 1400~1500℃ and the heat treatment pressure is 150~180MPa.

6. The method for preparing the ceramic chopping knife according to claim 1, characterized in that: Step S1 is as follows: the ceramic slurry is made into a ceramic chopping knife blank, the ceramic chopping knife blank is then debonded and sintered, and then finely processed into a finished ceramic chopping knife.

7. A ceramic chopping knife, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the ceramic cleaver of claim 7 in the field of device packaging.

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