Ceramic combined with grinding stone

Abstract

[Problem] To provide a ceramic-bonded grinding stone that can be manufactured at a relatively low sintering temperature and has a certain level of water resistance or strength. [Solution] A ceramic-bonded grinding stone has abrasive grains and a bonding material for fixing the abrasive grains. The bonding material comprises a base material mainly composed of silicon dioxide (SiO₂), a sintering aid oxide, and zinc oxide (ZnO). The zinc oxide (ZnO) content, by weight percentage, is 11 wt% or more and 15 wt% or less. Preferably, the sintering aid oxide content, by weight percentage, is 20 wt% or more and 29 wt% or less. Furthermore, preferably, the sintering aid oxide comprises one or more of sodium oxide (Na₂O), calcium oxide (CaO), potassium oxide (K₂O), and barium oxide (BaO). More preferably, the binder contains zirconium dioxide (ZrO2), and the content of zirconium dioxide (ZrO2) is 3 wt% or more and 5 wt% or less by weight of the binder.

Description

Ceramic combined with grinding stone The present invention relates to a ceramic-bonded grinding stone for use on a grinding wheel or the like, wherein the grinding wheel is a grinding wheel provided in a grinding device for grinding a workpiece. Device chips used in electronic devices such as mobile phones or personal computers can be manufactured from wafers formed of semiconductor materials such as silicon. By forming multiple devices on the front side and grinding the back side of the wafer to thin it to a predetermined thickness, and then dividing the wafer according to each device, individual device chips containing devices such as ICs and LSIs can be manufactured. A grinding apparatus (see, for example, Patent Document 1) can be used for grinding the back side of a wafer. The grinding apparatus includes an annular grinding wheel and a spindle that supports the grinding wheel to be rotatable. The grinding wheel includes an annular wheel base and a grinding stone arranged in a ring on one side of the wheel base. Grinding stones, especially those with ceramic bonding, are widely used as attachments to grinding wheels. Ceramic-bonded grinding stones use a bonding material (SiO₂) with glass as the main component. 2. Al 2O 3. B 2O The mixture (3) is mixed with abrasive grains and sintered to form the grinding stone. Because the sintering temperature is as high as 1200℃~1300℃, the abrasive grains contained in the grinding stone are prone to deterioration due to carbonization, etc. Using a grinding stone with deteriorated abrasive grains, even if grinding is performed, the grinding stone cannot achieve the expected performance. Furthermore, generally speaking, when grinding a workpiece using a grinding wheel equipped with a grinding stone, self-adhesive edge formation occurs. This self-adhesive edge formation is caused by the moderate consumption of the bonding material and the continuous exposure of unused abrasive grains contained within the grinding stone from the bonding material. Therefore, the grinding ability of the grinding stone can be maintained at a certain level. However, because ceramic-bonded grinding stones, which have a bonding material mainly composed of glass, are very hard and difficult to consume, it is difficult for self-adhesive edge formation to occur sufficiently, making it difficult to maintain a consistent grinding ability. Therefore, to make the grinding stone more brittle and easier to spontaneously sharpen, and to prevent the deterioration of the abrasive grains, the following technique has been implemented: further adding sintering aid oxides to the ceramic-bonded grinding stone material to lower the sintering temperature. Lowering the sintering temperature of the ceramic-bonded grinding stone moderately consumes the bonding material, making it easier for the grinding stone to spontaneously sharpen. Furthermore, as a sintering aid oxide, Na can be listed as an example. 2O, CaO, K 2O, BaO, Li 2O, etc. Previous technical documents and patent documents. Patent Document 1: Japanese Patent Application Publication No. 2000-288881 The problem the invention aims to solve However, these sintering aid oxides are easily soluble in water, which can lead to the following problems: the water resistance and strength of ceramic-bonded grinding stones manufactured by adding sintering aid oxides tend to decrease. During grinding, because grinding water is supplied to both the grinding wheel and the workpiece, and because a relatively large force is applied to the grinding stone, ceramic-bonded grinding stones with reduced water resistance and strength are difficult to use in practice. This invention was made in view of the aforementioned problems, and its object is to provide a ceramic-bonded grinding stone that can be manufactured at a relatively low sintering temperature and possesses a certain level of water resistance or strength. Means for solving the problems. According to one aspect of the present invention, a ceramic-bonded grinding stone is provided, comprising abrasive grains and a bonding material for fixing the abrasive grains, wherein the ceramic-bonded grinding stone is characterized in that: the bonding material comprises silicon dioxide (SiO₂). 2) It is composed of a base material as the main component, sintering aid oxides and zinc oxide (ZnO), and the content of zinc oxide (ZnO) is 11 wt% or more and 15 wt% or less based on the weight ratio of the binder. Preferably, the content of the sintering aid oxide is 20 wt% or more and 29 wt% or less, based on the weight ratio of the binder. Furthermore, preferably, the sintering aid oxide contains sodium oxide (Na₂O₃). 2O), calcium oxide (CaO), potassium oxide (K) One or more of the following: 2O and barium oxide (BaO). More preferably, the binder contains zirconium dioxide (ZrO2). 2), and based on the weight ratio of the binder, the zirconium dioxide (ZrO) 2) The content of [the substance] is 3 wt% or more but less than 5 wt%. Invention Effects One embodiment of the present invention is a ceramic-bonded grinding stone comprising abrasive grains and a bonding material. The bonding material comprises silicon dioxide (SiO₂). 2) It is composed of a base material as the main component, sintering aid oxides, and zinc oxide (ZnO). Furthermore, the content of zinc oxide (ZnO) is 11 wt% to 15 wt% by weight of the binder. A binder containing zinc oxide (ZnO) at a weight ratio of 11 wt% to 15 wt% has sufficient water resistance, allows for a relatively low sintering temperature, possesses strength capable of withstanding grinding, and is not so hard as to hinder the self-sparking process. Therefore, according to one aspect of the present invention, a ceramic-bonded grinding stone that can be manufactured at a lower sintering temperature and has a certain level of water resistance or strength can be provided. Forms used to implement inventions Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG1 is a perspective view schematically showing the structure of the grinding wheel 2 equipped with the ceramic-bonded grinding stone 6 of this embodiment. As shown in Figure 1, the grinding wheel 2 has a disc-shaped (ring-shaped) wheel base 4 made of stainless steel, aluminum, or the like. The wheel base 4 has a first surface 4a and a second surface 4b that are parallel to each other, and a circular opening 4c is formed in the center of the wheel base 4, extending from the first surface 4a to the second surface 4b. On the second surface 4b of the wheel base 4, a plurality of ceramic-bonded grinding stones 6 of this embodiment are arranged in a ring. The grinding wheel 2 is used as a grinding unit assembled into the grinding apparatus. Figure 2 schematically shows a side view of the workpiece 1 being ground by the grinding apparatus 8. Although the workpiece 1 is representative of semiconductor wafers, resin substrates, ceramic substrates, etc., the workpiece 1 is not limited to these. The grinding apparatus 8 includes a work chuck 10 for attracting and holding a workpiece 1, and a grinding unit 12 for grinding the workpiece 1 held in the work chuck 10. The work chuck 10 is connected to a suction source (not shown), and the negative pressure generated by the suction source acts on the workpiece 1 placed on the upper surface to attract and hold the workpiece 1. Furthermore, the work chuck 10 can rotate about a rotation axis substantially perpendicular to the upper surface by means of a rotation drive source (not shown). The grinding unit 12 includes a spindle 14 running approximately perpendicular to the upper surface of the work chuck 10, a rotary drive source 16 such as a motor connected to the upper end of the spindle 14 and rotating the spindle 14, and a wheel holder 18 connected to the lower end of the spindle 14. The grinding wheel 2 is fixed to the wheel holder 18 with the first surface 4a of the wheel base 4 in contact with the lower surface of the wheel holder 18. In this way, the second surface 4b of the wheel base 4, on which the ceramic-bonded grinding stone 6 is mounted, faces the upper surface of the work chuck 10. The worktable 10, which holds the workpiece 1, rotates about a rotation axis perpendicular to its upper surface. The rotary drive 16 is actuated to rotate the spindle 14, causing the ceramic-bonded abrasive stone 6 to move along a circular track and the grinding unit 12 to descend. In this way, the ceramic-bonded abrasive stone 6 contacts the workpiece 1 and grinds it. Then, the grinding unit 12 is lowered until the workpiece 1 reaches a predetermined thickness, ending the grinding process. When the workpiece 1 is ground with the ceramic-bonded abrasive stone 6, grinding chips or heat are generated from the workpiece 1 or the ceramic-bonded abrasive stone 6. Therefore, during the grinding of the workpiece 1, grinding water, such as pure water, can be supplied to the upper surface of the workpiece 1 and the grinding wheel 2 through a grinding water supply nozzle (not shown), and the grinding chips or heat are removed by the grinding water. From this perspective, the ceramic-bonded abrasive stone 6 needs to have a certain level of water resistance. The ceramic-bonded grinding stone 6 of this embodiment has a bonding material and numerous abrasive grains dispersed and fixed in the bonding material. The abrasive grains are formed of materials such as diamond and CBN (cubic boron nitride). Furthermore, the abrasive grains can be appropriately selected in terms of material, average grain size, and content in the bonding material, etc., according to the specifications of the ceramic-bonded grinding stone 6. When the ceramic-bonded abrasive stone 6 comes into contact with the workpiece 1, the workpiece 1 is ground by the abrasive grains, which are gradually consumed. At this time, because the bonding material is also gradually consumed, new abrasive grains are continuously exposed. Therefore, the grinding ability of the ceramic-bonded abrasive stone 6 can be maintained at a certain level. This effect is called self-sharpening. However, if the bonding material is too hard, it becomes difficult to generate wear, and the self-sharpening edge will not function properly, resulting in a decrease in the grinding ability of the ceramic-bonded abrasive stone 6. On the other hand, if the strength of the bonding material is too low, it will not be able to properly grind the workpiece 1. Therefore, the bonding material needs to have an appropriate level of hardness / strength. In manufacturing ceramic bonded grinding stones 6, abrasive grains are mixed into a component that serves as the bonding material, which is then shaped and sintered at a high temperature. The suitable sintering temperature varies depending on the composition of the component that serves as the bonding material. Since the abrasive grains will carbonize and deteriorate during sintering if the sintering temperature of the bonding material becomes too high, it is preferable to sinter the bonding material at a lower temperature. The bonding material of ceramic-bonded grinding stone 6 includes silicon dioxide (SiO2). 2) The base material is the main component. B may also be included in the binder. 2O 3 or Al 2O 3. As the parent material for forming glassy materials. However, only SiO2 is used. 2. Al 2O 3 and B 2O 3. The sintering temperature of the binder material, which is the main component, is as high as 1200℃~1300℃. If the ceramic-bonded grinding stone 6 is sintered at this temperature, the abrasive particles already dispersed in the binder material will deteriorate. Therefore, in the components that serve as the binder, sintering aid oxides are mixed in to lower the sintering temperature. These sintering aid oxides include, for example, sodium oxide (Na₂O₃). 2O), calcium oxide (CaO), potassium oxide (K) The sintering aid oxide is selected from one or more of barium oxide (BaO) and barium oxide (BaO). Preferably, the content of the sintering aid oxide is 20 wt% or more and 29 wt% or less, based on the weight percentage of the binder. If the sintering aid oxide is added to the binder, the sintering temperature decreases and the abrasive grains become less prone to deterioration during sintering. However, ceramic-bonded abrasive stones 6 made with binders containing sintering aid oxides tend to have the following characteristics: lower mechanical strength and lower water resistance. During grinding of the workpiece 1, a relatively large force is applied to the ceramic-bonded abrasive stone mounted on the grinding wheel 2. Furthermore, a grinding fluid containing water is supplied to the workpiece 1 during grinding. Therefore, if grinding is performed using a ceramic-bonded abrasive stone 6 with low mechanical strength and water resistance, the following problem arises: damage is easily caused to the ceramic-bonded abrasive stone 6. Therefore, in the ceramic-bonded grinding stone 6 of this embodiment, zinc oxide (ZnO), which is difficult to dissolve in water, is preferably mixed into the binder at a predetermined content. In particular, when the content of zinc oxide is 11 wt% or more and 15 wt% or less by weight of the binder, the sintering temperature can be kept relatively low, and the ceramic-bonded grinding stone 6 can have a water resistance and mechanical strength of a predetermined level or higher. Therefore, the ceramic-bonded grinding stone 6 of this embodiment has the properties suitable for grinding because it is sintered at a lower temperature, which allows it to be consumed moderately during grinding while maintaining sufficient mechanical strength or water resistance. In addition, zirconium dioxide (ZrO2) can also be used as a binder. 2) It is mixed with zinc oxide (ZnO) into the binder at a predetermined content. In particular, if calculated by weight ratio of the binder, zirconium dioxide (ZrO) is also incorporated. 2) When the content of [agent] is 3 wt% or more but less than 5 wt%, the water resistance and mechanical strength of the binder will be better. [Example] In this embodiment, a ceramic-bonded grinding stone 6 with a bonding material is fabricated, and its water resistance, mechanical strength, and sintering temperature during manufacturing are evaluated. The bonding material comprises silicon dioxide (SiO₂). 2) It is composed of a base material as the main component, sintering aid oxides, and zinc oxide (ZnO). Furthermore, in this embodiment, multiple ceramic bonding grinding stones 6 are made with different mixing ratios of the bonding material components, and these values ​​are evaluated for each. Here, the content of zinc oxide (ZnO) contained in the binder is set to be 11 wt% or more and 15 wt% or less, based on the weight ratio of the binder. Furthermore, for comparison, a ceramic-bonded grinding stone 6 with a zinc oxide (ZnO) content in the binder that does not meet this range is manufactured, and its water resistance, etc., are evaluated in the same way. As a material for ceramic-bonded grinding stone 6, silicon dioxide (SiO2) is prepared in a predetermined amount. 2) The main components are the base material, sintering aids oxide and zinc oxide (ZnO). Then, the materials are mixed in a predetermined manner, the mixture is placed in a mold frame to form, and sintered at the required temperature to manufacture ceramic-bonded grinding stones 6. Table 1 below shows the names of each ceramic-bonded grinding stone 6 and the weight ratio (wt%) of each material contained in the bonding material. Here, names meeting the following criteria are included with "Example," while names not meeting the following criteria are included with "Comparative Example": the content of zinc oxide (ZnO) contained in the bonding material is 11 wt% or more and 15 wt% or less, based on the weight ratio of the bonding material. Furthermore, in Table 1, the weight ratio of a portion of the constituent materials of the bonding material of the ceramic-bonded grinding stone 6 is omitted. Therefore, even if all the weight ratios of the base material, added oxides, and sintering aid oxides listed in the table are added, it will not necessarily reach 100 wt%. [Table 1] Next, a flexural strength test was conducted to evaluate the mechanical strength of each of the manufactured ceramic-bonded grinding stones 6. In the flexural strength test, a hardness measuring device "AGI-1kN" manufactured by Shimadzu Corporation was used. The pressure rate was set to 1 mm / min, and the load capacity was set to 0 N~1 kN. The manufactured ceramic-bonded grinding stones 6 were then pressed, and the pressure value at which failure occurred was recorded as the flexural strength. Then, the relative values ​​of the flexural strength of each ceramic-bonded grinding stone 6 were calculated when the flexural strength of the ceramic-bonded grinding stone of Comparative Example 1 was set to 100. The relative values ​​of the flexural strength of each ceramic-bonded grinding stone 6 are shown in Table 2 below. Furthermore, an evaluation test was conducted on the water resistance of each of the manufactured ceramic-bonded grinding stones 6. In the water resistance evaluation test, each ceramic-bonded grinding stone 6 was immersed in hot water for 5 hours, and its weight was measured before and after immersion. Moreover, hot water was used in this test because it was considered that the ceramic-bonded grinding stones would be heated by the heat generated during the grinding process, thus making the test environment similar to the environment during grinding. First, the weight of each ceramic-bonded grinding stone 6 was measured before immersion in hot water. Next, after immersion in hot water for 5 hours, the ceramic-bonded grinding stone 6 was dried, and its weight was measured again. Then, the weight of each ceramic-bonded grinding stone 6 before immersion was divided by its weight after immersion to determine its solubility. Furthermore, the relative solubility values ​​of each ceramic-bonded grinding stone in the examples were calculated when the solubility value of the ceramic-bonded grinding stone 6 of Comparative Example 1 was set to 100. The smaller this relative value of solubility, the lower the solubility in grinding water, meaning higher water resistance. That is, the smaller the weight change of the ceramic-bonded grinding stone 6 and the higher the water resistance, the lower this relative value will be. Table 2 below shows the relative values ​​of solubility for each ceramic-bonded grinding stone 6 in the embodiments. Also, in Table 2, the temperature required for sintering each ceramic-bonded grinding stone 6 is recorded as the sintering temperature. [Table 2] Ideally, the sintering temperature of the ceramic-bonded grinding stone 6 should be below 780°C. This is because if the sintering temperature exceeds this, the abrasive grains or fillers such as diamond and SiC already dispersed in the bonding material will deteriorate. Furthermore, since the ceramic-bonded grinding stones 6 of Comparative Examples 3, 4, 5, 6, and 7 require sintering temperatures above 800°C, it is considered that the abrasive grains may deteriorate and fail to achieve the desired grinding capability. Furthermore, the mechanical strength that the ceramic-bonded grinding stone 6 should possess when processing the workpiece 1 exceeds approximately 95 in the relative values ​​of the aforementioned flexural strength. Ceramic-bonded grinding stones 6 with flexural strength lower than this value will gradually deteriorate and fail during repeated grinding processes. Moreover, because the relative values ​​of the flexural strength of the ceramic-bonded grinding stones 6 in Comparative Examples 2 and 6 are lower than this value, they are evaluated as lacking the required mechanical strength. Furthermore, the water resistance that the ceramic-bonded grinding stone 6 should possess when processing the workpiece 1 is less than approximately 55 in the relative values ​​related to the aforementioned water resistance. If the relative value of water resistance is higher than this value, the bonding material will gradually dissolve into the supplied grinding water, and the ceramic-bonded grinding stone 6 will deteriorate and become unsuitable for proper grinding before the intended service life of one month has expired. Moreover, because the relative values ​​of water resistance of the ceramic-bonded grinding stones 6 in Comparative Examples 1, 2, and 7 exceed this value, they are evaluated as lacking the required water resistance. Furthermore, the ceramic-bonded grinding stones 6 of Examples 1 to 8 were all sintered at temperatures below 780°C, allowing the abrasive grains to fully perform their functions, and were also evaluated as having sufficient mechanical strength and water resistance. Therefore, it was confirmed that if, by weight of the bonding material, the content of zinc oxide (ZnO) contained in the bonding material is 11 wt% or more and 15 wt% or less, it will become a ceramic-bonded grinding stone 6 that can be manufactured at a lower sintering temperature and has a certain level of water resistance or strength. Furthermore, as can be understood from the relative value of the flexural strength of the ceramic-bonded grinding stone 6 in Comparative Example 6, if the ZnO content is excessive and the content of the sintering aid oxide becomes too low, the strength of the ceramic-bonded grinding stone 6 will decrease. On the other hand, as can be understood from the performance evaluation of the ceramic-bonded grinding stone 6 in Comparative Example 7, if the content of the sintering aid oxide becomes too high, the water resistance of the ceramic-bonded grinding stone 6 will become relatively low. Therefore, based on the weight ratio of the bonding material, the sintering aid oxide should preferably be 20 wt% or more and 29 wt% or less. Furthermore, as can be understood from the sintering temperature of the ceramic-bonded grinding stone 6 in Comparative Example 5, even if the content of the sintering aid oxide meets this range, the sintering temperature will actually increase if the content of ZnO does not meet the required amount. Therefore, ZnO must be included in the binder within the aforementioned range. Furthermore, as can be understood from the performance evaluation of the ceramic-bonded grinding stone 6 in Comparative Example 2, the following situation can be understood through this embodiment: When the bonding material contains Li... The water resistance of the ceramic-bonded grinding stone 6 with MgO content becomes relatively low. Furthermore, as understood from the performance of the ceramic-bonded grinding stone 6 in Comparative Example 4, the sintering temperature of the binder containing MgO is difficult to lower. Therefore, it is preferable that the binder of the ceramic-bonded grinding stone 6 does not contain Li. 2O and MgO. Furthermore, the following can be understood from the performance evaluation results of each ceramic-bonded grinding stone 6 in this embodiment: Besides ZnO, it is advisable to allow zirconium dioxide (ZrO) to be used. 2) It should be contained in the binder in a certain amount. That is, it is advisable to include zirconium dioxide (ZrO2) in the binder. 2) The ceramic-bonded grinding stone 6, and based on the weight ratio of the bonding material, the zirconium dioxide (ZrO) 2) The content of the substance is 3wt% or more and 5wt% or less. Furthermore, the present invention is not limited to the embodiments described above, and can be implemented with various modifications. The structure and method of the above embodiments can be appropriately modified and implemented as long as they do not depart from the purpose of the present invention. 1: Workpiece 2: Grinding wheel 4: Wheel base 4a: First surface 4b: Second surface 4c: Opening 6: Ceramic-bonded grinding stone 8: Grinding device 10: Work chuck 12: Grinding unit 14: Spindle 16: Rotary drive source 18: Wheel seat Figure 1 is a perspective view schematically showing the structure of the grinding wheel. Figure 2 is a side view schematically showing the workpiece being ground by the grinding device. 2: Grinding wheel 4: Wheel base platform 4a: Page 1 4b: Page 2 4c: Opening 6: Ceramic combined with grinding stone

Claims

1. A ceramic-bonded grinding stone, comprising abrasive grains and a bonding material for fixing the abrasive grains, characterized in that: the bonding material comprises a base material mainly composed of silicon dioxide (SiO2), sintering aid oxide, and zinc oxide (ZnO), wherein the content of zinc oxide (ZnO) is 11 wt% or more and 15 wt% or less by weight of the bonding material, and the bonding material comprises zirconium dioxide (ZrO2), wherein the content of zirconium dioxide (ZrO2) is 3 wt% or more and 5 wt% or less by weight of the bonding material.

2. The ceramic-bonded grinding stone of claim 1, wherein the content of the sintering aid oxide is 20 wt% or more and 29 wt% or less, based on the weight ratio of the bonding material.

3. The ceramic-bonded grinding stone as claimed in claim 1 or 2, wherein the sintering aid oxide comprises one or more of sodium oxide (Na2O), calcium oxide (CaO), potassium oxide (K2O), and barium oxide (BaO).

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