A device and method for quickly stripping the cathode plate of a microchannel semiconductor laser

Abstract

The present invention relates to a device and method for quickly stripping the negative electrode sheet of a microchannel semiconductor laser, and belongs to the field of semiconductor laser packaging technology. The device includes a bottom plate heating plate, a material tray, a storage tray, a biaxial motion platform, a lifting mechanism, a suction mechanism, and a stripping sheet. A heating plate is provided on one side of the bottom plate, a material tray is provided on the heating plate, and stripping sheets are evenly distributed in the material tray. A storage tray is provided on the other side of the bottom plate, a biaxial motion platform is provided above the bottom plate, a lifting mechanism is provided below the biaxial motion platform, and a suction mechanism is provided on the lifting mechanism. The present invention has a simple structure, is easy to operate, has high production efficiency, and has a high stripping qualification rate. It realizes the automation of the stripping process of the negative electrode sheet and reduces the labor intensity of personnel.

Description

Technical Field

[0001] The invention relates to a microchannel semiconductor laser cathode sheet rapid stripping device and stripping method, belonging to the technical field of semiconductor laser packaging. Background Art

[0002] In recent years, due to the unique characteristics of semiconductor lasers such as small size, light weight, high efficiency and reliability, the use of high-power semiconductor lasers has gradually expanded, and has been increasingly widely used in fields such as pumping, medical treatment, display lighting, laser processing and military. With the gradual optimization of high-power semiconductor laser chip structures and the advancement of packaging technology, the preparation and application of laser bar chip arrays with output power exceeding kilowatts have also grown rapidly. The use of laser bar chip arrays can greatly improve the output power and packaging density of semiconductor lasers, but it also causes a significant increase and concentration of chip heat generation. In order to achieve the best heat dissipation effect and ensure the normal operation of high-power semiconductor lasers, the packaging of array semiconductor lasers mainly uses microchannel heat sinks, which effectively evacuate the heat generated by the laser bar chips by passing cooling water.

[0003] Microchannel lasers are mainly composed of four parts: microchannel heat sink, cathode sheet, insulating sheet and bar. Currently, the microchannel laser packaging process is divided into indium process and gold-tin process, with the indium process being the main one. That is, a certain thickness of indium layer is evaporated between the microchannel heat sink and the cathode sheet, the laser components are fixed together by a packaging fixture, and placed in a vacuum sintering device for high-temperature sintering to complete the laser packaging.

[0004] Because microchannel lasers have relatively high power and require high inspection standards, current packaging technology cannot achieve 100% compliance. Therefore, after packaging, the lasers need to undergo multiple processes such as appearance inspection, aging, and testing to screen out lasers that do not meet the standards in terms of appearance, parameters, and performance. Unqualified lasers are generally disposed of as waste. However, the raw materials of microchannel lasers are expensive, with the material cost of each product alone reaching thousands of yuan. Recycling the heat sinks, cathode plates, and other materials of unqualified lasers can avoid resource waste and reduce production costs.

[0005] To recycle microchannel laser materials, the sintered negative electrode sheet must first be peeled off from the heat sink. The currently commonly used method for peeling off the negative electrode sheet is to place the laser on a flat plate, use a blade to cut a notch in the indium layer between the negative electrode sheet and the heat sink, lift up a corner of the negative electrode sheet with tweezers, and then clamp the negative electrode sheet with flat-nose pliers. Pull the negative electrode sheet upward and peel the negative electrode sheet off the heat sink. This operation method is relatively simple, but the efficiency is relatively low. Only 2-3 negative electrode sheets can be peeled off per minute, and the long-term operation is labor-intensive. At the same time, since the negative electrode sheet is made of copper foil with a thickness of only about 0.1 mm and is relatively soft, the indium layer between the negative electrode sheet and the heat sink is sintered and solidified at high temperature, so the bonding force between the negative electrode sheet and the heat sink is relatively strong. During the manual peeling of the negative electrode sheet, if the force is too small, the negative electrode sheet cannot be completely peeled off from the heat sink, leaving residue or being unable to be peeled off. If the force is too large, the negative electrode sheet can easily be torn and damaged, resulting in scrapping, which seriously affects the material recovery rate after the negative electrode sheet is peeled. Therefore, the present invention is proposed to solve the problems existing in the current negative electrode sheet peeling. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides a microchannel semiconductor laser negative electrode sheet rapid stripping device with simple structure, easy operation, high production efficiency, high stripping qualification rate, and realizes the automation of the negative electrode sheet stripping process, reducing the labor intensity of personnel.

[0007] The present invention also provides a stripping method of the microchannel semiconductor laser cathode plate rapid stripping device.

[0008] The technical solutions of the present invention are as follows:

[0009] A microchannel semiconductor laser cathode rapid stripping device comprises a bottom plate, a heating plate, a material tray, a storage tray, a biaxial motion platform, a lifting mechanism, a suction mechanism and a stripping sheet, wherein:

[0010] A heating plate is provided on one side of the bottom plate, a material tray is provided on the heating plate, peeling sheets are evenly distributed in the material tray, a storage tray is provided on the other side of the bottom plate, a dual-axis motion platform is provided above the bottom plate, a lifting mechanism is provided below the dual-axis motion platform, and a suction mechanism is provided on the lifting mechanism.

[0011] Preferably, a heating groove is provided inside the heating plate, a heating rod is provided in the heating groove, a heat insulation plate is provided between the heating plate and the bottom plate, and a heat conducting plate is provided between the heating plate and the material tray.

[0012] Further preferably, a positioning protrusion is provided on the heat conducting plate, and a groove is provided below the material tray, and the material tray and the heat conducting plate are positioned and fixed by the groove and the positioning protrusion.

[0013] Preferably, the material tray includes a chassis and a cover plate, the chassis is evenly arranged with positioning grooves, a groove is provided under the chassis, the cover plate is evenly arranged with penetrating positioning square holes, the positioning square holes correspond to the positions of the positioning grooves, and the cover plate is fixed above the chassis by bolts.

[0014] Further preferably, the length and width of the positioning groove are the same as the length and width of the microchannel laser, and the length and width of the positioning square hole are smaller than the length and width of the microchannel laser, ensuring that after the cover plate is covered with the chassis, the positioning square hole can fix the microchannel laser.

[0015] Preferably, the stripping sheet is made of a metal material with good magnetism, and a glue layer is provided under the stripping sheet. The glue layer is made of thermosetting glue. The glue layer is sticky at high temperature and has no stickiness at low temperature and room temperature. The stripping sheet is used to bond with the negative electrode sheet at high temperature to strip the negative electrode sheet. The length and width of the stripping sheet are adapted to the length and width of the negative electrode sheet.

[0016] Preferably, the storage tray includes a tray body and a storage sheet. The tray body is provided with a storage sheet, which is provided with adhesive for placing the peeled negative electrode sheet so that the negative electrode sheet will not move on the storage sheet.

[0017] Further preferably, positioning blocks are provided on the bottom plates at the four corners of the tray body, and the tray body is fixed and positioned by the positioning blocks.

[0018] Preferably, the lifting mechanism includes a linear slide, a lifting cylinder, a lifting block, and a connecting block. The upper end of the linear slide is connected to the dual-axis motion platform. A lifting cylinder is provided on one side of the linear slide, and the lifting cylinder is connected to the lifting block. The lifting cylinder can control the vertical movement of the lifting block. A connecting block is provided at the bottom of the lifting block, and a suction mechanism is provided at one end of the connecting block. The position of the lifting cylinder is adjusted by moving the linear slide left and right, thereby adjusting the left and right positions of the connecting block and the suction mechanism, thereby achieving fine-tuning of the suction mechanism.

[0019] Further preferably, the suction mechanism includes an electromagnet and a suction plate, wherein the suction plate is disposed below the electromagnet, and suction blocks are symmetrically disposed below the suction plate. When the electromagnet is energized, the suction plate has a strong magnetism, and when the electromagnet is de-energized, the magnetism of the suction plate disappears. The length and width of the suction block are the same as those of the peeling sheet, and the peeling sheet is sucked by the suction block.

[0020] The stripping method of the microchannel semiconductor laser cathode quick stripping device is as follows:

[0021] (1) Arrange the microchannel lasers of the negative electrode sheet to be peeled evenly in the positioning groove of the chassis with the front side facing upward;

[0022] (2) Place the cover plate on the upper end of the chassis and fix the cover plate and chassis together;

[0023] (3) Place the peeling sheet with the adhesive layer facing downward and place it on the upper end of the negative electrode sheet of the microchannel laser through the positioning square hole on the cover plate;

[0024] (4) Place the assembled tray on the heat conducting plate and secure it with screws;

[0025] (5) The heating rod is heated. When the temperature of the material tray rises to 160 degrees Celsius, the indium layer of the microchannel laser melts, the adhesive layer of the peeling sheet becomes more viscous, and the peeling sheet and the negative electrode sheet are bonded together;

[0026] (6) The dual-axis motion platform moves, and the positions of the lifting mechanism and the suction mechanism are adjusted. The suction mechanism is moved to the top of the positioning square hole of the material tray. The lifting mechanism drives the suction mechanism downward, so that the suction block contacts the stripping sheet. Then, the electromagnet is energized, and the suction block sucks the stripping sheet and moves upward, so that the negative electrode sheet is stripped from the microchannel laser.

[0027] (7) The suction mechanism moves to the top of the storage tray, and then the lifting mechanism drives the suction block to move downward, so that the negative electrode sheet contacts the storage sheet, and then the electromagnet is powered off, and the negative electrode sheet and the stripping sheet combination is fixed on the storage sheet, and the suction mechanism continues to strip the negative electrode sheet of the remaining microchannel laser;

[0028] (8) After the storage tray is filled with negative electrode sheets, remove the storage tray from the device and place it in a low-temperature box to cool the peeling sheet to below 0 degrees Celsius to eliminate the stickiness of the peeling sheet glue layer;

[0029] (9) The stripping sheet is separated from the negative electrode sheet, and the negative electrode sheet is recycled, completing the rapid stripping of the negative electrode sheet of the microchannel laser.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention has a simple structure, convenient operation, high production efficiency, high stripping qualification rate, and realizes automation of the stripping process of the negative electrode sheet, thereby reducing the labor intensity of personnel.

[0032] 2. The present invention uses two suction blocks to simultaneously strip two laser cathode sheets. The stripping efficiency is increased from 2-3 sheets per minute to more than 60 sheets per minute, and the cathode sheet stripping efficiency is increased by more than 20 times.

[0033] 3. When the present invention is used to peel the negative electrode sheet, the negative electrode sheet always remains flat, and the structure and shape of the negative electrode sheet remain in their original state. This effectively solves the problem that when manually peeling the negative electrode sheet, the negative electrode sheet cannot be completely peeled off on the heat sink due to insufficient force, resulting in residue or failure to peel off, and the problem that excessive force can easily cause the negative electrode sheet to be torn and damaged and scrapped. The qualified rate of negative electrode sheet peeling has increased from 60% to more than 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the three-dimensional structure of the present invention Figure I .

[0035] Figure 2 Schematic diagram of the three-dimensional structure of the present invention Figure II .

[0036] Figure 3 It is a partially enlarged three-dimensional structural schematic diagram of the present invention.

[0037] Figure 4 It is a schematic diagram of the three-dimensional structure of the suction mechanism of the present invention.

[0038] Figure 5 It is a schematic diagram of the three-dimensional structure of the heating plate of the present invention.

[0039] Figure 6 Schematic diagram of the three-dimensional structure of the heat conducting plate of the present invention.

[0040] Figure 7 It is a schematic diagram of the three-dimensional structure of the material tray of the present invention.

[0041] Figure 8 Schematic diagram of the three-dimensional structure of the chassis of the present invention Figure I .

[0042] Figure 9 Schematic diagram of the three-dimensional structure of the chassis of the present invention Figure II .

[0043] Figure 10 It is a schematic diagram of the three-dimensional structure of the cover plate of the present invention.

[0044] Figure 11 Schematic diagram of the three-dimensional structure of the release sheet of the present invention.

[0045] Figure 12 Schematic diagram of the three-dimensional structure of the microchannel laser.

[0046] Among them: 1. bottom plate, 2. heat insulation plate, 3. heating plate, 4. material tray, 5. storage tray, 6. positioning block, 7. linear slide rail, 8. lifting cylinder, 9. lifting block, 10. connecting block, 11. suction mechanism, 12. heating rod, 13. storage sheet, 14. heat conducting plate, 15. microchannel laser, 16. peeling sheet, 17. electromagnet, 18. suction plate, 19. suction block, 20. heating tank, 21. positioning protrusion, 22. chassis, 23. cover plate, 24. fixing screw, 25. positioning groove, 26. fixing screw hole I, 27. fixing screw hole II, 28. groove, 29. positioning square hole, 30. fixing hole, 31. adhesive layer, 32. heat sink, 33. negative electrode sheet. DETAILED DESCRIPTION

[0047] The present invention will be further described below with reference to embodiments and accompanying drawings, but is not limited thereto.

[0048] Example 1:

[0049] like Figure 1-12 As shown, this embodiment provides a microchannel semiconductor laser cathode rapid stripping device, including a base plate 1, a heating plate 3, a material tray 4, a storage tray 5, a biaxial motion platform, a lifting mechanism, a suction mechanism 11 and a stripping sheet 16, wherein:

[0050] A heating plate 3 is mounted on one side of the base plate 1, on which a material tray 4 is mounted. Within this tray 4, peeling sheets 16 are evenly distributed. A storage tray 5 is located on the other side of the base plate 1. A dual-axis motion platform is located above the base plate 1, and a lifting mechanism is located below the dual-axis motion platform. A suction mechanism 11 is mounted on the lifting mechanism. The dual-axis motion platform is an existing X-axis and Y-axis mobile platform, not shown in the figure. Its installation location can be determined based on the installation environment.

[0051] A heating groove 20 is provided inside the heating plate 3, and a heating rod 12 is provided in the heating groove 20. A heat insulation plate 2 is provided between the heating plate 3 and the bottom plate 1. The heat insulation plate 2 is made of a material with good heat insulation effect. The heat insulation plate is mainly used to prevent the heat generated on the heating plate from being transferred to the bottom plate, and plays a protective role. A heat conduction plate 14 is provided between the heating plate 3 and the material tray 4. The heat conduction plate 14 is made of a metal material with good heat conductivity. The heat conduction plate is mainly used to fix the material tray and transfer the heat generated by the heating rod to the material tray.

[0052] The tray 4 comprises a base 22 and a cover 23. The base is made of metal with good thermal conductivity. Positioning slots 25 are evenly spaced on the base 22, and a groove 28 is provided below the base 22. The cover 23 is evenly spaced with through-holes 29, which correspond to and are the same number as the positioning slots 25. Fixing screw holes I 26 are provided at the four corners of the base 22, and symmetrical fixing screw holes II 27 are provided on both sides of the base 22. Fixing holes 30 are provided at the four corners of the cover 23. The cover 23 is secured to the base 22 by fixing screws 24.

[0053] The stripping sheet 16 is made of a metal material with good magnetism. A glue layer 31 is provided under the stripping sheet 16. The glue layer 31 is made of thermosetting glue. The glue layer 31 is sticky at high temperatures and has no stickiness at low temperatures and room temperatures. The stripping sheet 16 is used to bond with the negative electrode sheet 33 at high temperatures to strip the negative electrode sheet 33. The length and width of the stripping sheet 16 are adapted to the length and width of the negative electrode sheet 33.

[0054] The storage tray 5 includes a tray body and a storage sheet 13 . The storage sheet 13 is provided in the tray body. The storage sheet 13 is attached with adhesive for placing the peeled negative electrode sheet 33 so that the negative electrode sheet 33 will not move on the storage sheet 13 .

[0055] The lifting mechanism includes a linear slide 7, a lifting cylinder 8, a lifting block 9, and a connecting block 10. The upper end of the linear slide 7 is connected to the dual-axis motion platform. A lifting cylinder 8 is provided on one side of the linear slide 7. The lifting cylinder 8 is connected to the lifting block 9. The lifting cylinder 8 can control the vertical movement of the lifting block 9. The bottom of the lifting block 9 is provided with a connecting block 10, and one end of the connecting block 10 is provided with a suction mechanism 11. By adjusting the position of the lifting cylinder by moving the linear slide 7 left and right, the left and right positions of the connecting block and the suction mechanism can be adjusted to achieve fine-tuning of the suction mechanism.

[0056] The suction mechanism includes an electromagnet 17 and a suction plate 18. The suction plate 18 is positioned below the electromagnet 17, and suction blocks 19 are symmetrically positioned below the suction plate 18. When the electromagnet 17 is energized, the suction plate 18 becomes strongly magnetic. When the electromagnet 17 is de-energized, the suction plate 18 loses its magnetism. The length and width of the suction block 19 are the same as those of the stripping sheet 16, allowing the stripping sheet 16 to be sucked in by the suction block 19.

[0057] The stripping method of the microchannel semiconductor laser cathode quick stripping device is as follows:

[0058] (1) Arrange the microchannel lasers with the negative electrode sheet 33 to be peeled evenly in the chassis positioning groove 25 with the front side facing upward;

[0059] (2) Place the cover plate 23 on the upper end of the chassis 22 and bolt the cover plate 23 and chassis 22 together;

[0060] (3) Place the peeling sheet 16 with the adhesive layer facing downward and onto the upper end of the negative electrode sheet 33 of the microchannel laser through the positioning square hole 29 on the cover plate 23;

[0061] (4) Place the assembled tray 4 on the heat conducting plate 14 and fix it with screws;

[0062] (5) The heating rod 12 is heated. When the temperature of the material tray 4 reaches 160 degrees Celsius, the indium layer of the microchannel laser melts, the adhesive layer of the peeling sheet 16 becomes more viscous, and the peeling sheet 16 is bonded to the negative electrode sheet 33;

[0063] (6) The dual-axis motion platform moves, and the positions of the lifting mechanism and the suction mechanism 11 are adjusted. The suction mechanism 11 is moved to above the positioning square hole 29 of the material tray. The lifting mechanism drives the suction mechanism 11 downward, so that the suction block 19 contacts the stripping sheet 16. Then, the electromagnet 17 is energized, and the suction block 19 sucks the stripping sheet 16 and moves upward, so that the negative electrode sheet 33 is stripped from the microchannel laser.

[0064] (7) The suction mechanism 11 moves to the top of the storage tray 5, and then the lifting mechanism drives the suction block 19 to move downward, so that the negative electrode sheet 33 contacts the storage sheet 13, and then the electromagnet 17 is powered off, and the combination of the negative electrode sheet 33 and the stripping sheet 16 is fixed on the storage sheet 13, and the suction mechanism 11 continues to strip the negative electrode sheets of the remaining microchannel lasers;

[0065] (8) After the storage sheet 13 is filled with negative electrode sheets 33, the storage tray 5 is removed from the device and placed in a low-temperature box to cool the peeling sheet 16 to below 0 degrees Celsius to eliminate the stickiness of the peeling sheet adhesive layer;

[0066] (9) The stripping sheet 16 is separated from the negative electrode sheet 33, and the negative electrode sheet 33 is recycled, completing the rapid stripping of the negative electrode sheet of the microchannel laser.

[0067] Example 2:

[0068] A device for quickly stripping the negative electrode sheet of a microchannel semiconductor laser has a structure as described in Example 1, except that a positioning protrusion 21 is provided on the heat conducting plate 14, and a groove 28 is provided under the material tray 4. The material tray 4 and the heat conducting plate 14 are positioned and fixed by the groove 28 and the positioning protrusion 21.

[0069] Example 3:

[0070] A device for quickly stripping the negative electrode sheet of a microchannel semiconductor laser has a structure as described in Example 1, except that the length and width of the positioning groove 25 are the same as the length and width of the microchannel laser 15, and the length and width of the positioning square hole 29 are smaller than the length and width of the microchannel laser 15, ensuring that the positioning square hole can fix the microchannel laser after the cover plate 23 is covered with the chassis.

[0071] Example 4:

[0072] A microchannel semiconductor laser cathode rapid stripping device has the same structure as that described in Example 1, except that positioning blocks 6 are provided on the bottom plate 1 at the four corners of the disc body, and the disc body is fixed and positioned by the positioning blocks 6.

Claims

1. A stripping method for a microchannel semiconductor laser cathode quick stripping device, characterized in that: The device includes a bottom plate, a heating plate, a material tray, a storage tray, a biaxial motion platform, a lifting mechanism, a suction mechanism and a peeling sheet, wherein: A heating plate is provided on one side of the bottom plate, a material tray is provided on the heating plate, peeling sheets are evenly distributed in the material tray, a storage tray is provided on the other side of the bottom plate, a dual-axis motion platform is provided above the bottom plate, a lifting mechanism is provided below the dual-axis motion platform, and a suction mechanism is provided on the lifting mechanism; A heating tank is provided inside the heating plate, a heating rod is provided in the heating tank, a heat insulation plate is provided between the heating plate and the bottom plate, and a heat conducting plate is provided between the heating plate and the material tray; The tray includes a base plate and a cover plate. Positioning grooves are evenly arranged on the base plate, a groove is provided under the base plate, and positioning square holes are evenly arranged on the cover plate. The positioning square holes correspond to the positioning grooves. The cover plate is fixed to the top of the base plate by bolts. The storage tray includes a tray body and a storage sheet. The tray body is provided with a storage sheet, and the storage sheet is provided with adhesive. The lifting mechanism includes a linear slide, a lifting cylinder, a lifting block and a connecting block. The upper end of the linear slide is connected to the dual-axis motion platform. A lifting cylinder is provided on one side of the linear slide. The lifting cylinder is connected to the lifting block. A connecting block is provided at the bottom of the lifting block. A suction mechanism is provided at one end of the connecting block. The suction mechanism includes an electromagnet and a suction plate. The suction plate is provided below the electromagnet, and suction blocks are symmetrically provided below the suction plate. The stripping method of the microchannel semiconductor laser cathode quick stripping device is as follows: (1) Arrange the microchannel semiconductor lasers with the negative electrode to be peeled off evenly in the positioning groove of the chassis with the front side facing upward; (2) Place the cover plate on the upper end of the chassis and fix the cover plate and chassis together; (3) Place the peeling sheet with the adhesive layer facing downwards on the upper end of the negative electrode sheet of the microchannel semiconductor laser through the positioning square hole on the cover plate; (4) Place the assembled tray on the heat conducting plate and fix it; (5) The heating rod is heated. When the temperature of the material tray rises to 160 degrees Celsius, the indium layer of the microchannel semiconductor laser melts, the adhesive layer of the peeling sheet becomes more viscous, and the peeling sheet and the negative electrode sheet are bonded together; (6) The dual-axis motion platform moves, and the position of the lifting mechanism and the suction mechanism is adjusted. The suction mechanism is moved to the top of the positioning square hole of the material tray. The lifting mechanism drives the suction mechanism downward, so that the suction block contacts the stripping sheet. Then, the electromagnet is energized, and the suction block sucks the stripping sheet and moves upward, so that the negative electrode sheet is stripped from the microchannel semiconductor laser. (7) The suction mechanism moves to the top of the storage tray, and then the lifting mechanism drives the suction block to move downward, so that the negative electrode sheet contacts the storage sheet, and then the electromagnet is powered off, and the negative electrode sheet and the stripping sheet combination is fixed on the storage sheet, and the suction mechanism continues to strip the negative electrode sheet of the remaining microchannel semiconductor laser; (8) After the storage tray is filled with negative electrode sheets, remove the storage tray from the device and place it in a low-temperature box to cool the peeling sheet to below 0 degrees Celsius to eliminate the stickiness of the peeling sheet glue layer; (9) The stripping sheet is separated from the negative electrode sheet, and the negative electrode sheet is recycled, completing the rapid stripping of the negative electrode sheet of the microchannel semiconductor laser.

2. The stripping method of the microchannel semiconductor laser cathode rapid stripping device according to claim 1, characterized in that: A positioning protrusion is provided on the heat conducting plate, and a groove is provided under the material tray. The material tray and the heat conducting plate are positioned and fixed by the groove and the positioning protrusion.

3. The stripping method of the microchannel semiconductor laser cathode rapid stripping device according to claim 1, characterized in that: The length and width of the positioning groove are the same as those of the microchannel semiconductor laser, and the length and width of the positioning square hole are smaller than those of the microchannel semiconductor laser.

4. The stripping method of the microchannel semiconductor laser cathode rapid stripping device according to claim 1, characterized in that: The peeling sheet is made of metal material with good magnetism, and an adhesive layer is arranged under the peeling sheet, and the adhesive layer is made of thermosetting adhesive.

5. The stripping method of the microchannel semiconductor laser cathode rapid stripping device according to claim 1, characterized in that: Positioning blocks are provided on the bottom plate at the four corners of the disc body.

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