Substrate grinding device and substrate grinding method

Abstract

To provide a substrate grinding device and a substrate grinding method capable of grinding a large substrate efficiently and highly accurately.SOLUTION: A substrate grinding device includes: a work table 20 that rotates in a state of suction-holding a substrate 30; a cup wheel type first grinding stone 11 that grinds the substrate 30 while rotating the substrate 30 that is held by the work table 20 and rotates; and a cup wheel type second grinding stone 15 that grinds the substrate 30 while rotating the substrate 30 that is held by the work table 20 and rotates. The first grinding stone 11 and the second grinding stone 15 are provided at positions at which the grinding stones can simultaneously contact with the rotating substrate 30. The work table 20 can move from a first grinding position 25 at which the rotation center of the substrate 30 is within a grinding range of the first grinding stone 11 to a second grinding position 26 at which the rotation center of the substrate 30 is within a grinding range of the second grinding stone 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate grinding apparatus and a substrate grinding method, and more particularly to a substrate grinding apparatus and a substrate grinding method suitable for grinding large mounting substrates. [Background technology]

[0002] In recent years, substrates, which are the objects of grinding, have become larger. Examples of this type of large substrate include WLP (Wafer Level Package) and PLP (Panel Level Package), which is an even larger version of WLP and is a large-sized mounting substrate. Therefore, there is a demand for technology to grind these types of large substrates efficiently and with high precision.

[0003] Patent Document 1 discloses a substrate grinding device used for grinding this type of large substrate. The substrate grinding device disclosed in this document is equipped with a cup wheel type finish grinding wheel that grinds the substrate held and rotated on a work table while rotating, and a cup wheel type rough grinding wheel that approaches the substrate and grinds it while rotating simultaneously with the finish grinding wheel.

[0004] With this configuration, large mounting substrates such as PLPs with large warpage can be ground simultaneously with the finish grinding wheel and the rough grinding wheel without transporting them on a turntable, etc. Therefore, large substrates can be ground with high precision in a short time without increasing the size of the substrate grinding device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-40189 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned conventional substrate grinding apparatuses have some points that need improvement in order to realize efficient grinding processing. Specifically, the conventional substrate grinding device disclosed in Patent Document 1 can grind a substrate simultaneously with a finish grinding wheel and a rough grinding wheel without moving the substrate, thereby enabling efficient grinding processing.

[0007] However, in the substrate grinding apparatus of the document, the rough grinding wheel is positioned so that its grinding range does not pass through the center of rotation of the substrate, and therefore it is not possible to grind the vicinity of the center of rotation of the substrate. In other words, even if rough grinding is performed, convex portions that are not ground are left near the center of rotation of the substrate. The convex portions left near the center of rotation of the substrate are ground only by the finish grinding wheel.

[0008] Therefore, conventional substrate grinding devices have the problem that the amount of grinding required by the finish grinding wheel is large, making it difficult to shorten the grinding time.In addition, the finish grinding wheel wears a lot and needs to be replaced frequently, which increases the production cost of substrates.

[0009] In particular, in recent years, there has been a demand for even higher precision processing of the surfaces of large mounting substrates such as PLP, and there is a demand for the use of grinding wheels with smaller abrasive grain sizes than conventional grinding wheels as finish grinding wheels.

[0010] As mentioned above, conventional substrate grinding devices require the use of a finish grinding wheel to grind the convex portions near the center of rotation of the substrate, which places restrictions on the choice of finish grinding wheel that can grind the convex portions.

[0011] For example, even if it is required to use a finishing grinding wheel with a grit size of #8000 to grind the work surface of a substrate with high precision, conventional substrate grinding devices take a long time to grind the convex parts near the center of rotation, and the finishing grinding wheel wears out quickly, making it difficult to put into practical use.

[0012] The present invention has been made in consideration of the above circumstances, and its object is to provide a substrate grinding apparatus and a substrate grinding method that can grind large substrates efficiently and with high precision. [Means for solving the problem]

[0013] The substrate grinding apparatus of the present invention comprises a work table that rotates while holding a substrate by suction, a first grinding wheel of a cup wheel type that grinds the substrate held on the work table while rotating, and a second grinding wheel of a cup wheel type that grinds the substrate held on the work table while rotating, wherein the first grinding wheel and the second grinding wheel are provided at positions where they can simultaneously come into contact with the rotating substrate, the abrasive grain size of the first grinding wheel is larger than the abrasive grain size of the second grinding wheel, and the work table is movable from a first grinding position where the center of rotation of the substrate is within the grinding range of the first grinding wheel to a second grinding position where the center of rotation of the substrate is within the grinding range of the second grinding wheel. After grinding of the substrate by the first grinding wheel at the first grinding position, the work table moves from the first grinding position to the second grinding position, and at the second grinding position, the first grinding wheel and the second grinding wheel simultaneously rotate and approach the substrate to grind the substrate, and then, with the first grinding wheel separated from the substrate, the second grinding wheel approaches the substrate to grind the substrate. It is characterized by:

[0014] The substrate grinding method of the present invention includes a chucking step of chucking a substrate onto a rotatable work table, a transport step of sending the work table holding the substrate to a first grinding position below a first grinding wheel and a second grinding wheel of a cup wheel type, a first grinding step of rotating the work table at the first grinding position to rotate the substrate held therein and also to rotate the first grinding wheel to grind the substrate, and after the first grinding step, a step of transporting the work table holding the substrate to a first grinding position below a first grinding wheel. and a second grinding step of rotating the work table at the second grinding position to rotate the substrate held thereon and rotating the second grinding wheel to grind the substrate, wherein the abrasive grain size of the first grinding wheel is larger than the abrasive grain size of the second grinding wheel, and the center of rotation of the substrate at the first grinding position is within the grinding range of the first grinding wheel, and the center of rotation of the substrate at the second grinding position is within the grinding range of the second grinding wheel. In the second grinding step, the first grinding wheel and the second grinding wheel simultaneously rotate and approach the substrate to grind the substrate, and then, with the first grinding wheel separated from the substrate, the second grinding wheel approaches the substrate to grind the substrate. It is characterized by: [Effects of the Invention]

[0015] The substrate grinding apparatus of the present invention includes a first grinding wheel and a second grinding wheel, both of which are cup wheels, that grind a substrate held on a work table while rotating. The first grinding wheel and the second grinding wheel are positioned so that they can simultaneously contact the rotating substrate. The work table is movable from a first grinding position, where the center of rotation of the substrate is within the grinding range of the first grinding wheel, to a second grinding position, where the center of rotation of the substrate is within the grinding range of the second grinding wheel. This configuration allows the first grinding wheel and the second grinding wheel to be appropriately set, allowing for efficient and high-precision grinding of substrates. For example, the first grinding wheel can be used as a rough grinding wheel and the second grinding wheel as a finish grinding wheel, allowing for efficient grinding from rough grinding to finish grinding.

[0016] Furthermore, because the first grinding wheel and the second grinding wheel are positioned so that they can simultaneously contact the rotating substrate, they can be easily moved from the first grinding position to the second grinding position. Unlike conventional substrate grinding devices, which require rough grinding and finish grinding positions at separate locations and require substrates to be transferred and transported on work tables that move between the respective positions, there is no need for a large turntable or the like on which multiple work tables can be placed. Therefore, the substrate grinding device of the present invention can efficiently and accurately grind large mounting substrates such as PLPs while minimizing the footprint of the device.

[0017] Furthermore, according to the substrate grinding apparatus of the present invention, grinding of the substrate may be performed by the first grinding wheel at the first grinding position, and grinding of the substrate may be performed by the second grinding wheel at the second grinding position.

[0018] As a result, at the first grinding position, the first grinding wheel can grind the entire surface to be processed, including the area near the rotation center of the substrate, and at the second grinding position, the second grinding wheel can grind the entire surface to be processed, including the area near the rotation center of the substrate, thereby making it possible to efficiently grind the surface to be processed of the substrate with high precision by effectively using both the first grinding wheel and the second grinding wheel.

[0019] Specifically, the first grinding wheel is a rough grinding wheel with a large abrasive grain size, and the second grinding wheel is a finish grinding wheel with a small abrasive grain size.The first grinding wheel can rough grind the entire area of ​​the substrate's work surface, and then the second grinding wheel can finish grind the entire area of ​​the substrate's work surface.

[0020] In other words, the entire processed surface of the substrate can be flattened by efficient rough grinding without leaving any unground convex portions near the center of rotation of the substrate, and then finish grinding can be performed. The second grinding wheel used for finish grinding does not need to grind away the convex portions left near the center of rotation of the substrate, as in conventional substrate grinding devices. Therefore, by using a finish grinding wheel with a smaller abrasive grain size than in conventional techniques, the processed surface of the substrate can be finished with high precision in a short grinding process.

[0021] Furthermore, since the second grinding wheel does not need to grind the protrusions near the center of rotation of the substrate, the amount of wear is kept small, which reduces the amount of grinding wheel used and reduces the production cost of the substrate.

[0022] Furthermore, according to the substrate grinding apparatus of the present invention, the first grinding wheel and the second grinding wheel may be capable of grinding the substrate simultaneously at the second grinding position, thereby enabling grinding to be performed simultaneously using, for example, a first grinding wheel with a large abrasive grain size for rough grinding and a second grinding wheel with a small abrasive grain size for finish grinding, thereby improving the efficiency of the grinding process.

[0023] Furthermore, the substrate grinding method of the present invention includes a chucking step of adsorbing a substrate onto a rotatable work table, a transport step of sending the work table holding the substrate to a first grinding position below a first grinding wheel and a second grinding wheel of a cup wheel type, a first grinding step of rotating the work table at the first grinding position to rotate the held substrate and also rotate the first grinding wheel to grind the substrate, and a second grinding step of grinding the substrate after the first grinding step. The grinding machine includes a position change step of sending the held work table to a second grinding position below the first grinding wheel and the second grinding wheel, and a second grinding step of rotating the work table at the second grinding position to rotate the held substrate and also rotate the second grinding wheel to grind the substrate, where at the first grinding position the center of rotation of the substrate is within the grinding range of the first grinding wheel and at the second grinding position the center of rotation of the substrate is within the grinding range of the second grinding wheel. This enables large-sized mounting substrates such as PLPs to be ground efficiently and with high precision.

[0024] Furthermore, according to the substrate grinding method of the present invention, in the second grinding step, the first grinding wheel and the second grinding wheel may simultaneously rotate and approach the substrate to grind the substrate, and then the second grinding wheel may approach the substrate with the first grinding wheel separated from the substrate to grind the substrate. This makes it possible to perform grinding using the first grinding wheel and the second grinding wheel simultaneously between, for example, a rough grinding step using the first grinding wheel with a large abrasive grain size and a finish grinding step using the second grinding wheel with a small abrasive grain size, thereby improving the efficiency of the grinding process. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a plan view showing an outline of a substrate grinding apparatus according to an embodiment of the present invention; [Figure 2] 1 is a plan view showing the vicinity of a grinding stage at a first grinding position of a substrate grinding apparatus according to an embodiment of the present invention. [Figure 3]1 is a vertical cross-sectional view schematically showing the vicinity of a grinding stage at a first grinding position of a substrate grinding apparatus according to an embodiment of the present invention. [Figure 4] 3 is a plan view showing the vicinity of the grinding stage at a second grinding position of the substrate grinding apparatus according to the embodiment of the present invention. FIG. [Figure 5] 3 is a vertical cross-sectional view schematically showing the vicinity of a grinding stage at a second grinding position of the substrate grinding apparatus according to the embodiment of the present invention. FIG. [Figure 6] 3 is a vertical cross-sectional view schematically showing the vicinity of the rotation center of a substrate in a rough grinding step of a substrate grinding apparatus according to an embodiment of the present invention. FIG. [Figure 7] 3 is a vertical cross-sectional view schematically showing the vicinity of the rotation center of a substrate in a finish grinding process of a substrate grinding apparatus according to an embodiment of the present invention. FIG. [Figure 8] FIG. 10 is a vertical cross-sectional view schematically showing the vicinity of the rotation center of the substrate in another example of the second grinding step of the substrate grinding apparatus according to the embodiment of the present invention. [Figure 9] FIG. 10 is a vertical cross-sectional view schematically showing the vicinity of the rotation center of the substrate in another example of the second grinding step of the substrate grinding apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A substrate grinding apparatus according to an embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a plan view showing an outline of a substrate grinding apparatus 10 according to an embodiment of the present invention. Referring to FIG. 1, a substrate grinding apparatus 10 is an apparatus for grinding or polishing a substrate 30. The substrate 30 is made of a silicon dioxide powder.

[0027] The substrate 30, which is the object to be processed by the substrate grinding apparatus 10, may be, for example, a large-area mounting substrate such as PLP, a package substrate, other laminated substrates, a semiconductor substrate, a substrate for elements such as a capacitor, etc. The substrate grinding apparatus 10 grinds or polishes with high precision the resin layer, copper electrodes, semiconductor elements, etc. that constitute the substrate 30 from the main surface of the substrate 30, and can efficiently process even a warped large-area substrate 30.

[0028] The substrate grinding apparatus 10 has a standby stage 23 for placing the substrate 30, which is the object to be processed, a grinding stage 24 for grinding the substrate 30, a work table 20 for holding the substrate 30, a rough grinding wheel 11, which is a first grinding wheel, and a finish grinding wheel 15, which is a second grinding wheel.

[0029] The standby stage 23 is a stage for fixing the substrate 30 to be processed to the work table 20 before processing, and for removing the chuck of the substrate 30 from the work table 20 after grinding processing.

[0030] Above the standby stage 23, an attachment housing 22 is provided for adsorbing the substrate 30 to the vacuum chuck of the work table 20. In the standby stage 23, the substrate 30 placed on the upper surface of the work table 20 is sandwiched between the attachment housing 22 descending from above and the work table 20 below, and is fixed to the work table 20 by vacuum suction. After the substrate 30 is fixed to the work table 20, the attachment housing 22 moves up, away from the substrate 30.

[0031] The work table 20 is a table that rotates while holding the substrate 30 during the grinding process, and is configured to be able to move approximately horizontally between the standby stage 23 and the grinding stage 24 to transport the substrate 30.

[0032] Specifically, after the substrate 30 is adsorbed onto the upper surface of the work table 20 on the standby stage 23, the work table 20 moves to a predetermined position on the grinding stage 24 and rotates while supporting the substrate 30. After grinding of the substrate 30 is completed, the work table 20 moves to a predetermined position on the standby stage 23.

[0033] The work table 20 is movable from a first grinding position 25 (see FIG. 2) where the rotation center 21 of the substrate 30 is within the grinding range of the rough grinding wheel 11 to a second grinding position 26 (see FIG. 4) where the rotation center 21 is within the grinding range of the finish grinding wheel 15. Details will be described later.

[0034] The grinding stage 24 is a position for performing the grinding process of the substrate 30. The substrate 30, which is sucked onto the upper surface of the work table 20, is transported to the grinding stage 24 together with the work table 20, and the grinding process of the substrate 30 is performed by the rough grinding wheel 11 and the finish grinding wheel 15.

[0035] The rough grinding wheel 11 is a cup wheel type grinding wheel that grinds the substrate 30 while rotating, and is supported so as to be movable in the vertical direction by a rough grinding column 13. The rough grinding wheel 11 is provided above the work table 20 and the substrate 30 that are transported to the grinding stage 24.

[0036] The finish grinding wheel 15 is a cup wheel type grinding wheel that grinds the substrate 30 while rotating, and is supported so as to be movable in the vertical direction by a finish grinding column 17. The finish grinding wheel 15 is provided above the work table 20 and the substrate 30 that are transported to the grinding stage 24.

[0037] The grinding stage 24 is provided with a sizing device 28. The sizing device 28 is a device that accurately detects the position of the upper surface of the substrate 30 and measures the processing dimensions of the substrate 30 in order to grind the substrate 30 with high precision.

[0038] The substrate grinding apparatus 10 is provided with a control panel 27. The control panel 27 has an input section for inputting various information, a monitor for displaying various information, a calculation section for performing various calculations, etc. The control panel 27 executes various calculations based on the input information, and monitors and controls the processing in the substrate grinding apparatus 10 as a whole.

[0039] The substrate grinding apparatus 10 may also be provided with a cleaning liquid spraying device (not shown) for cleaning the rough grinding wheel 11 and the finish grinding wheel 15. The cleaning liquid spraying device has a spray nozzle for spraying cleaning liquid onto the rough grinding wheel 11 and a spray nozzle for spraying cleaning liquid onto the finish grinding wheel 15.

[0040] The cleaning liquid is sprayed from the spray nozzle at a pressure of, for example, 3 MPa to 17 MPa near the grinding wheel cutting edges 12, 16 (see FIG. 3) of the rough grinding wheel 11 and the finish grinding wheel 15, which are away from the substrate 30. This makes it possible to wash away shavings adhering to the rough grinding wheel 11 and the finish grinding wheel 15 during the grinding process, and to grind the substrate 30 with high precision.

[0041] Fig. 2 is a plan view showing the vicinity of the grinding stage 24 at the first grinding position 25 of the substrate grinding apparatus 10. Fig. 3 is a vertical cross-sectional view schematically showing the vicinity of the grinding stage 24 at the first grinding position 25.

[0042] 2 and 3, the rough grinding wheel 11 and the finish grinding wheel 15 are provided at positions where they can simultaneously come into contact with the upper surface 31 of the rotating substrate 30 during the grinding process. Specifically, during the grinding process, the rough grinding wheel 11 is above the substrate 30 and is at a position where it can come into contact with the upper surface 31 of the substrate 30 when it is lowered, and the finish grinding wheel 15 is also above the substrate 30 and is at a position where it can come into contact with the upper surface 31 of the substrate 30 when it is lowered.

[0043] The first grinding position 25 is the position of the substrate 30 where a first grinding step (described later) is performed. Note that in Fig. 2, the first grinding position 25 indicates the position of the rotation center 21 of the substrate 30 in the horizontal feed direction when the first grinding step is performed, i.e., the position in the direction of the arrow in Fig. 2. The second grinding position 26 indicates the position of the rotation center 21 of the substrate 30 when a second grinding step (described later) is performed. At the first grinding position 25 of the grinding stage 24, above the substrate 30, a rough grinding wheel 11 and a finish grinding wheel 15 for grinding the substrate 30 are provided side by side.

[0044] The rough grinding wheel 11 is provided at a position where the diameter of the grinding range is larger than the radius of the work table 20 and the grinding range passes through the rotation center 21 of the substrate 30. This allows the rough grinding wheel 11 to roughly grind the entire upper surface 31, which is the surface to be processed of the substrate 30.

[0045] The rough grinding wheel 11 is a wheel that mainly performs rough grinding of the substrate 30, and the finish grinding wheel 15 is a wheel that mainly performs finish grinding of the substrate 30. Therefore, the abrasive grain size of the finish grinding wheel 15 is smaller than the abrasive grain size of the rough grinding wheel 11. In other words, the grit size of the finish grinding wheel 15 is larger than the grit size of the rough grinding wheel 11. In addition, the diameter of the finish grinding wheel 15 may be approximately the same as the diameter of the rough grinding wheel 11.

[0046] The finish grinding wheel 15 has a diameter of a grinding range larger than the radius of the work table 20, is close to the rotation center 21 of the substrate 30, and is provided at a position where it does not come into contact with the rough grinding wheel 11.

[0047] Fig. 4 is a plan view showing the vicinity of the grinding stage 24 at the second grinding position 26 of the substrate grinding apparatus 10. Fig. 5 is a vertical cross-sectional view schematically showing the vicinity of the grinding stage 24 at the second grinding position 26.

[0048] 4 and 5, second grinding position 26 is a position of substrate 30 where a second grinding step, which will be described later, is performed. Note that in Fig. 4, first grinding position 25 and second grinding position 26 indicate positions in the horizontal feed direction of rotation center 21 of substrate 30, i.e., positions in the direction of the arrows in Fig. 4.

[0049] As described above, the work table 20 that holds the substrate 30 is provided so that its position can be adjusted between the first grinding position 25 and the second grinding position . At the second grinding position 26 of the grinding stage 24 , the rough grinding wheel 11 is provided at a position close to the rotation center 21 of the substrate 30 and not in contact with the finish grinding wheel 15 .

[0050] The finish grinding wheel 15 is provided at a position where its grinding range passes through the rotation center 21 of the substrate 30. This allows the finish grinding wheel 15 to finish-grind the entire upper surface 31, which is the surface to be processed of the substrate 30, with high precision.

[0051] That is, at the first grinding position 25, the substrate grinding device 10 can grind the entire surface to be processed, including the vicinity of the rotation center 21 of the substrate 30, with the rough grinding wheel 11, and at the second grinding position 26, the entire surface to be processed, including the vicinity of the rotation center 21 of the substrate 30, with high precision with the finish grinding wheel 15.

[0052] Specifically, the first grinding wheel is a rough grinding wheel 11 with a large abrasive grain size, and the second grinding wheel is a finish grinding wheel 15 with a small abrasive grain size. After the first grinding wheel rough-grinds the entire area of ​​the work surface of the substrate 30, the second grinding wheel finish-grinds the entire area of ​​the work surface of the substrate 30. In this way, the substrate grinding apparatus 10 can appropriately set the first grinding wheel and the second grinding wheel, and can grind the substrate 30 efficiently and with high precision.

[0053] Furthermore, since the rough grinding wheel 11 and the finish grinding wheel 15 are provided in close proximity to each other so that they can simultaneously come into contact with the rotating substrate 30, movement from the first grinding position 25 to the second grinding position 26 is also easy.

[0054] The substrate grinding device 10 does not require the installation of separate table installation facilities for rough grinding and finish grinding at separate locations, unlike conventional general substrate grinding devices, and the substrate 30 does not need to be transferred and transported on separate work tables that are moved to the respective table installation facilities.

[0055] Therefore, the substrate grinding apparatus 10 can significantly reduce the production time required for transportation, thereby improving production efficiency. Furthermore, since rough grinding and finish grinding can be performed consecutively without the need to reposition the substrate 30 held by suction on the work table 20, problems such as warping caused by repositioning the substrate 30 are eliminated, and a highly accurate flat surface can be efficiently formed on the processed surface of the substrate 30.

[0056] Furthermore, there is no need to install devices corresponding to the two processes at separate locations, and there is also no need to install a large turntable or the like on which multiple work tables can be placed. This reduces the footprint, i.e., the area occupied, of the substrate grinding apparatus 10, allowing for efficient grinding of large substrates 30. This provides a compact, high-performance substrate grinding apparatus 10 that can handle large mounting substrates such as PLPs.

[0057] For example, even if the substrate 30 to be processed is a large-sized mounting substrate such as PLP with a large warp, it can be ground efficiently by suitably using the rough grinding wheel 11 and the finish grinding wheel 15 without providing a turntable or the like to transport the work table 20. In this way, the substrate grinding device 10 realizes a high-precision grinding process in a short time.

[0058] That is, the entire processing surface of the substrate 30 can be flattened by efficient rough grinding without leaving any unground convex portions 32 (see FIG. 8) near the rotation center 21 of the substrate 30, and then finish grinding can be performed. The second grinding wheel used for finish grinding does not need to grind away the convex portions 32 remaining near the rotation center 21 of the substrate 30, as in the substrate grinding device of the prior art. Therefore, by using the finish grinding wheel 15 with a smaller abrasive grain size than in the prior art, the processing surface of the substrate 30 can be finished with high precision in a short grinding process.

[0059] Furthermore, the amount of wear of the finish grinding wheel 15 is kept small because it is not necessary to grind the protrusions 32 near the rotation center 21 of the substrate 30. This allows for a reduction in the amount of finish grinding wheel 15 used, thereby reducing the production cost of the substrate 30.

[0060] Next, a substrate manufacturing method using the substrate grinding apparatus 10 will be described in detail. Referring to FIG. 1, first, a chucking step is performed in which a substrate 30 is sucked onto a rotatable work table 20.

[0061] In the chucking process, a substrate 30, which is an object to be processed, is placed on the upper surface of the work table 20 on the standby stage 23 by a robot or the like. Then, the attachment housing 22 descends from above the substrate 30, and the substrate 30 is vacuum-adsorbed onto the work table 20.

[0062] Then, a transfer process is performed in which the work table 20 holding the substrate 30 is sent to a grinding position below the rough grinding wheel 11 and the finish grinding wheel 15. In the transfer process, the work table 20 holding the substrate 30 moves from the standby stage 23 to the grinding position of the grinding stage 24, more specifically, to the first grinding position 25 (see FIG. 2).

[0063] A grinding step for grinding the substrate 30 is performed in the grinding stage 24. More specifically, a first grinding step for grinding the substrate 30 with the rough grinding wheel 11 is performed in the first grinding position 25, and a second grinding step for grinding the substrate 30 with the finish grinding wheel 15 is performed in the second grinding position 26 (see FIG. 4).

[0064] In the grinding process, first, the thickness of the substrate 30 is measured by the sizing device 28, and the rough grinding wheel 11 is positioned at a height higher than the upper surface 31 (see FIG. 3) of the substrate 30 by an amount corresponding to the air cut.

[0065] In the grinding process, the substrate 30 held on the work table 20 rotates together with the work table 20, and is ground by the rough grinding wheel 11 or the finish grinding wheel 15 which descends to contact the work table 20 while rotating. The grinding process will be described in detail later.

[0066] After the grinding process, the substrate 30 is moved together with the work table 20 from the grinding stage 24 to the standby stage 23. Then, the substrate 30 after grinding is released from the vacuum suction and removed from the work table 20.

[0067] Next, the grinding process of the substrate 30 by the substrate grinding apparatus 10 will be described in detail with reference to FIGS. FIG. 6 is a vertical cross-sectional view that schematically shows the vicinity of rotation center 21 of substrate 30 in the rough grinding step.

[0068] 6, the grinding process begins with a rough grinding step, which is the first grinding step. In the rough grinding step, substrate 30 is at first grinding position 25, and rough grinding wheel 11 approaches substrate 30 from above to grind upper surface 31 of substrate 30.

[0069] Specifically, the control panel 27 (see FIG. 1) rotates the work table 20 (see FIG. 3) to rotate the substrate 30 held thereon, and also rotates the rough grinding wheel 11 to feed it downward.

[0070] As a result, the grinding edge 12 of the rotating rough grinding wheel 11 comes into contact with the upper surface 31 of the substrate 30, which rotates around the rotation center 21 within the grinding range of the rough grinding wheel 11, and the entire upper surface 31 of the substrate 30 is ground.

[0071] The cutting speed of the rough grinding wheel 11 in the rough grinding step is preferably, for example, 10 to 300 μm / min, and more preferably 30 to 300 μm / min, which reduces wear of the rough grinding wheel 11 and enables efficient, high-precision grinding.

[0072] The cutting edge 16 of the finish grinding wheel 15 is located above the cutting edge 12 of the rough grinding wheel 11. In other words, the cutting edge 16 of the finish grinding wheel 15 is located above and away from the base plate 30, and no grinding is performed by the finish grinding wheel 15.

[0073] In this manner, in the rough grinding process, the center of rotation 21 of the substrate 30 is within the grinding range of the rough grinding wheel 11, and the rough grinding wheel 11, which has a large abrasive grain size and is less worn, efficiently grinds the entire upper surface 31, including the vicinity of the center of rotation 21 of the substrate 30.

[0074] Next, after the rough grinding step is performed, a position change step is performed in which the work table 20 holding the substrate 30 is sent to a second grinding position 26 below the rough grinding wheel 11 and the finish grinding wheel 15.

[0075] 3, in the position change step, the rough grinding wheel 11 that has completed the grinding process rises and moves away from the upper surface 31 of the substrate 30. That is, the cutting edge 12 of the rough grinding wheel 11 moves away from the upper surface 31 of the substrate 30 in a manner similar to that of the cutting edge 16 of the finish grinding wheel 15.

[0076] Then, the substrate 30 moves horizontally together with the work table 20 and is sent to a second grinding position 26 where the rotation center 21 of the substrate 30 is within the grinding range of the finish grinding wheel 15, as shown in FIG.

[0077] FIG. 7 is a vertical cross-sectional view that schematically shows the vicinity of rotation center 21 of substrate 30 in the finish grinding step. 7, after the substrate 30 is sent to the second grinding position 26 in the position changing step, a finish grinding step is performed as the second grinding step. In the finish grinding step, the substrate 30 is ground by the finish grinding wheel 15, which is the second grinding wheel.

[0078] Specifically, with the rough grinding wheel 11 not in contact with the upper surface 31 of the substrate 30, the control panel 27 (see Figure 1) rotates the work table 20 (see Figure 3) to rotate the substrate 30 held thereon, and also rotates the finish grinding wheel 15 to feed it downward.

[0079] As a result, the grinding edge 16 of the rotating finish grinding wheel 15 comes into contact with the upper surface 31 of the substrate 30, which rotates around the rotation center 21 within the grinding range of the finish grinding wheel 15, and the entire upper surface 31 of the substrate 30 is ground.

[0080] The cutting speed of the finish grinding wheel 15 in the finish grinding step is, for example, 5 to 300 μm / min, preferably 5 to 100 μm / min, and more preferably 10 to 100 μm / min, which reduces wear on the finish grinding wheel 15 and enables efficient, high-precision finish grinding.

[0081] The finish grinding wheel 15 has a grit size of, for example, #4000 to #30000, preferably #8000 to #30000, in order to grind the work surface of the substrate 30 with high precision. In the substrate grinding apparatus 10, the entire upper surface 31 of the substrate 30 is ground with the rough grinding wheel 11 as a first grinding wheel, and then the upper surface 31 of the substrate 30 is ground with the finish grinding wheel 15 as a second grinding wheel.

[0082] Therefore, the substrate grinding apparatus 10 can use a high-grit grinding wheel, which was difficult to use with conventional technology, as the finish grinding wheel 15. This allows for high-precision substrate grinding, which was difficult with conventional substrate grinding apparatuses, and makes it possible to efficiently and accurately flatten large mounting substrates such as PLPs.

[0083] The machining allowance of the finish grinding wheel 15 in the finish grinding process is extremely small, and there is little wear on the finish grinding wheel 15. Specifically, compared to conventional grinding methods in which one type of grinding wheel is used to perform all grinding processes from rough grinding to finish grinding, the substrate grinding apparatus 10 can flatten the surface to be processed with higher precision, and can reduce the grinding time to about half or less and the running costs of the grinding wheel to about one-quarter or less.

[0084] FIG. 8 is a vertical cross-sectional view schematically showing the vicinity of rotation center 21 of substrate 30 as another example in the second grinding step. 8, in the substrate grinding apparatus 10, the rough grinding wheel 11 and the finish grinding wheel 15 can simultaneously grind the substrate 30 at the second grinding position 26. That is, the rough grinding wheel 11 and the finish grinding wheel 15 may be controlled to simultaneously rotate and simultaneously approach the substrate 30 held by the work table 20 and rotate, thereby grinding the substrate 30 simultaneously.

[0085] Specifically, as shown in FIG. 6, a first grinding step using only the rough grinding wheel 11 may be performed at the first grinding position 25, and after the position of the substrate 30 is changed to the second grinding position 26 in the position change step, a grinding step may be performed using both the rough grinding wheel 11 with a large abrasive grain size for rough grinding and the finish grinding wheel 15 with a small abrasive grain size for finish grinding, as shown in FIG.

[0086] In the grinding process using the rough grinding wheel 11 and the finish grinding wheel 15 simultaneously, the rough grinding wheel 11 and the finish grinding wheel 15 approach the substrate 30 and grind the substrate 30, with the grinding edge 12 of the rough grinding wheel 11 closer to the upper surface 31 of the substrate 30 than the grinding edge 16 of the finish grinding wheel 15, i.e., with the grinding edge 12 lower than the grinding edge 16.

[0087] The distance from the cutting edge 16 of the finish grinding wheel 15 to the cutting edge 12 of the rough grinding wheel 11 below is, for example, 1 to 50 μm, preferably 1 to 30 μm. It is also possible to feed the rough grinding wheel 11 and the finish grinding wheel 15 at the same cutting speed while maintaining their relative positions.

[0088] In this way, when grinding at the second grinding position 26, grinding is performed with the rough grinding wheel 11 closer to the substrate 30, and the grinding wheel 11, which has a large abrasive grain size and is less worn, can efficiently grind a wide range of the substrate 30 except for the vicinity of the rotation center 21.

[0089] At the second grinding position 26, the finish grinding wheel 15, which can grind the entire substrate 30 including the rotation center 21, moves down while rotating simultaneously with the rough grinding wheel 11. This allows the finish grinding wheel 11 to grind the convex portion 32 near the rotation center 21 of the substrate 30 that was not ground because the rough grinding wheel 11 did not come into contact with it.

[0090] FIG. 9 is a vertical cross-sectional view schematically showing the vicinity of the rotation center of the substrate 30 in another example of the second grinding step of the substrate grinding apparatus 10. In FIG. After the grinding process using both the rough grinding wheel 11 and the finish grinding wheel 15 shown in Fig. 8 is performed, the rough grinding wheel 11 moves higher than the finish grinding wheel 15, as shown in Fig. 9. That is, the grinding edge 12 of the rough grinding wheel 11 is higher than the grinding edge 16 of the finish grinding wheel 15 and is separated from the upper surface 31 of the substrate 30.

[0091] Then, the finish grinding wheel 15 rotates and comes into contact with the substrate 30, grinding the substrate 30, while the rough grinding wheel 11 is not in contact with the upper surface 31 of the substrate 30. As a result, the convex portion 32 near the rotation center 21 of the substrate 30, which was not ground because the grinding edge 12 of the rough grinding wheel 11 did not come into contact with it, is ground by the finish grinding wheel 11.

[0092] As already explained with reference to Figure 6, the upper surface 31 of the substrate 30 is ground by the rough grinding wheel 11 in the first grinding step at the first grinding position 25. Then, as shown in Figures 8 and 9, the grinding range of the finish grinding wheel 15 in the second grinding step performed at the second grinding position 26 is a narrow range near the rotation center 21. Therefore, the amount of wear on the finish grinding wheel 15 can be kept small.

[0093] As shown in Fig. 9, after the convex portion 32 is ground by the finish grinding wheel 11, grinding of the substrate 30 is continued by the finish grinding wheel 11 as shown in Fig. 7. Then, as already described, the entire upper surface 31 of the substrate 30 is finish-ground with high precision by the grinding edge 12 of the finish grinding wheel 11 to be flattened.

[0094] As explained above, in this embodiment, efficient grinding is performed while reducing the number of times the work table 20 is transported and the footprint of the device. In addition, large mounting substrates and the like can be ground efficiently and with high precision while reducing the amount of polishing required by the finish grinding wheel 15.

[0095] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0096] 10. Substrate grinding equipment 11 Rough grinding wheel 12 Grinding edge 13 Rough Grinding Column 15 Finish grinding wheel 16 Grinding wheel cutting edge 17 Finish Grinding Column 20 Work Table 21 Center of rotation 22 Adhesive housing 23 Standby Stage 24 grinding stage 25 First grinding position 26 Second grinding position 27 Control Panel 28 Sizing device 30 boards 31 Top side 32 Convex part

Claims

1. A work table that rotates while holding a substrate by suction; a first grinding wheel of a cup wheel type that grinds the substrate while rotating the substrate held and rotated on the work table; a second grinding wheel of a cup wheel type that grinds the substrate while rotating the substrate held and rotated on the work table; the first grinding wheel and the second grinding wheel are provided at positions where they can simultaneously come into contact with the rotating substrate, The abrasive grain size of the first grinding wheel is larger than the abrasive grain size of the second grinding wheel; the work table is movable from a first grinding position where the rotation center of the substrate is within the grinding range of the first grinding wheel to a second grinding position where the rotation center of the substrate is within the grinding range of the second grinding wheel; after grinding of the substrate by the first grinding wheel at the first grinding position, the work table moves from the first grinding position to the second grinding position; a substrate grinding apparatus characterized in that the first grinding wheel and the second grinding wheel simultaneously rotate at the second grinding position to approach the substrate and grind the substrate, and then, with the first grinding wheel separated from the substrate, the second grinding wheel approaches the substrate and grinds the substrate.

2. a chucking step of adsorbing the substrate onto a rotatable work table; a transport step of transporting the work table holding the substrate to a first grinding position below a first grinding wheel and a second grinding wheel of a cup wheel type; a first grinding step of rotating the work table at the first grinding position to rotate the substrate held thereon and also rotating the first grinding wheel to grind the substrate; a position changing step of sending the work table holding the substrate to a second grinding position below the first grinding wheel and the second grinding wheel after the first grinding step has been performed; a second grinding step of rotating the work table at the second grinding position to rotate the substrate held thereon and also rotating the second grinding wheel to grind the substrate, The abrasive grain size of the first grinding wheel is larger than the abrasive grain size of the second grinding wheel; At the first grinding position, a rotation center of the substrate is within a grinding range of the first grinding wheel; At the second grinding position, the rotation center of the substrate is within the grinding range of the second grinding wheel; a second grinding wheel that is rotated at the same time as the first grinding wheel and the second grinding wheel that are moved toward the substrate and grind the substrate; a second grinding wheel that is moved away from the substrate and the second grinding wheel that is moved toward the substrate and grind the substrate;

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