Waxless pad for preventing wafer penetration during polishing of optical crystal wafers and process for making same

Abstract

The application discloses a wax-free pad for resisting wafer penetration during polishing of an optical wafer and a preparation process thereof, and belongs to the technical field of wax-free pads. The wax-free pad comprises a substrate disc, an adsorption pad and a protective pad. The substrate disc is provided with a wafer placing groove. The wafer placing groove is provided with the adsorption pad for adsorbing the wafer. The adsorption pad is clamped on the substrate disc through the protective pad. The protective pad is used for resisting wafer penetration and fixing the adsorption pad on the substrate disc. The application solves the problem that the existing optical wafer has poor use effect during polishing because the wafer is easy to slide in the wafer placing groove during polishing, the wafer cannot be well protected, and the wafer cannot resist wafer penetration. The protective pad is arranged in the wafer placing groove, the protective pad is assembled on the substrate disc, the adsorption pad is assembled on the protective pad, the adsorption pad is pressed in the wafer placing groove, the wafer can be well protected by the protective pad, the wafer can effectively resist wafer penetration, and the use effect of the wax-free pad is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waxless pads, in particular to an anti-wafer penetration waxless pad for polishing optical crystal wafers and a preparation process thereof. BACKGROUND

[0002] In the processing of optical crystal wafers, polishing treatment is often required, and the quality of the optical crystal wafers will be directly affected by the polishing technology. There are mainly two traditional polishing technologies: wax polishing and waxless polishing. In the wax polishing technology, the optical crystal wafer is fixed on the flat plate of a ceramic disc, and the ceramic disc is rotated on the polishing cloth by the polishing head during polishing, and the polishing is realized under the action of mechanical pressure and polishing liquid. It is found in practice that this wax polishing has the defects of wax pollution and low polishing precision. Therefore, the advantages of waxless polishing are gradually reflected.

[0003] A waxless pad for polishing is disclosed in Chinese Patent No. CN112873074B, which comprises a base disc, a wafer placing hole, a clamping pad, and a waxless adsorption pad. At least one wafer placing hole is provided on the surface of the base disc, and a waxless adsorption pad for adsorbing the wafer is provided in the wafer placing hole. At least one layer of clamping pad is provided between the waxless adsorption pad and the inner bottom of the wafer placing hole. A composite resin is produced by reacting epoxy resin and polyurethane prepolymer, and the composite resin is used as the adhesive layer. The adhesive layer has the properties of both epoxy resin and polyurethane resin, with high adhesion and elasticity, and can be well bonded with the carbon fiber layer and the adsorption layer, avoiding delamination of the waxless adsorption pad. However, the patent has the following defects:

[0004] In the existing polishing of optical crystal wafers, the wafers are prone to sliding from the wafer placing groove during polishing. Since the wafers are not well protected, they cannot resist wafer penetration well, resulting in poor use effect of the waxless pad. SUMMARY

[0005] The present application provides an anti-wafer penetration waxless pad for polishing optical crystal wafers and a preparation process thereof. The protective pad can effectively protect the wafers and resist wafer penetration, improving the use effect of the waxless pad and solving the problems raised in the background technology.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The anti-wafer penetration waxless pad for polishing optical crystal wafers comprises a substrate disc, an adsorption pad, and a protective pad. The substrate disc is provided with a wafer placing groove for placing the wafer. The wafer placing groove is provided with an adsorption pad for adsorbing the wafer. The adsorption pad is clamped on the substrate disc by the protective pad. The protective pad is used to resist wafer penetration and to stabilize the adsorption pad on the substrate disc.

[0008] Preferably, the number of wafer placing grooves arranged on the substrate disc is 1 or 3 or 6.

[0009] Preferably, the substrate disc comprises the following raw materials in mass fraction: iron powder 40-60 parts, silicon nitride powder 10-30 parts, niobium carbide powder 10-20 parts and binder 1-3 parts.

[0010] Preferably, the adsorbing pad is made of polyurethane foaming material, and a first annular clamping groove for connecting the protective pad is arranged on the side end surface of the adsorbing pad.

[0011] Preferably, the protective pad comprises an annular protective base layer, a first annular clamping block and a second annular clamping block, the inner surface of the annular protective base layer is provided with the first annular clamping block, and the outer surface of the annular protective base layer is provided with the second annular clamping block.

[0012] Preferably, a second annular clamping groove for connecting the protective pad is arranged on the substrate disc, the second annular clamping groove and the second annular clamping block are matched, and the protective pad is connected with the substrate disc in interference by extruding the second annular clamping block into the second annular clamping groove.

[0013] Preferably, the first annular clamping groove and the first annular clamping block are matched, and the adsorbing pad is connected with the protective pad in interference by extruding the first annular clamping block into the first annular clamping groove.

[0014] Preferably, the annular protective base layer, the first annular clamping block and the second annular clamping block are integrally formed, and each of the annular protective base layer, the first annular clamping block and the second annular clamping block comprises the following raw materials in mass fraction: thermoplastic polyurethane elastomer 20-30 parts, polyurethane fiber 22-32 parts and auxiliary agent 5-16 parts.

[0015] According to another aspect of the present application, a preparation process of the wax-free pad against wafer penetration for polishing optical crystal wafer is provided for preparing the wax-free pad against wafer penetration for polishing optical crystal wafer as described above, comprising the following steps:

[0016] S1, preparing a substrate disc:

[0017] The iron powder, the silicon nitride powder and the niobium carbide powder are added into a mixing machine for uniform mixing, and then transferred into a ball mill for ball milling, with a ball-to-material ratio of 10:1, a ball milling speed of 300-400 r / min and a ball milling time of 4-6 h. The mixed powder after ball milling is ground for 10-20 min, and then moved into a vacuum drying box for drying for 3 h at a drying temperature of 100℃. The binder is added into the mixed powder after drying, and then transferred into a forming mold for sintering and forming. The blank disc of the formed substrate disc is cooled at room temperature, and cooled to room temperature. The wafer placing groove is processed on the blank disc of the substrate disc.

[0018] S2, preparing the adsorption pad:

[0019] The polyurethane foam material is injection molded, demolded, and a first annular clamping groove is processed on the side end face of the adsorption pad;

[0020] S3, preparing the protective pad:

[0021] The thermoplastic polyurethane elastomer, the polyurethane fiber and the auxiliary agent are fully mixed and melted, and then transferred into a forming mold for forming, and after demolding, an integrally formed annular protective base layer, a first annular clamping block and a second annular clamping block are obtained;

[0022] S4, preparing the wax-free pad:

[0023] The second annular clamping block is extruded into the second annular clamping groove, so that the protective pad is assembled on the substrate disc, the first annular clamping block is extruded into the first annular clamping groove, so that the adsorption pad is assembled on the protective pad, and the adsorption pad is pressed in the wafer placing groove, and after assembly, the wax-free pad is formed.

[0024] Compared with the prior art, the beneficial effects of the present application are:

[0025] The present application adds a protective pad in the wafer placing groove, extrudes the second annular clamping block into the second annular clamping groove, assembles the protective pad on the substrate disc, extrudes the first annular clamping block into the first annular clamping groove, assembles the adsorption pad on the protective pad, and presses the adsorption pad in the wafer placing groove, so that the wafer can be better protected by the protective pad, the wafer penetration can be effectively resisted, and the use effect of the wax-free pad is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic view of the anti-wafer penetration wax-free pad of the first embodiment of the present application;

[0027] Figure 2 It is a schematic view of the anti-wafer penetration wax-free pad of the second embodiment of the present application;

[0028] Figure 3 It is a schematic view of the anti-wafer penetration wax-free pad of the third embodiment of the present application;

[0029] Figure 4 It is an exploded view of the anti-wafer penetration wax-free pad of the third embodiment of the present application;

[0030] Figure 5 It is a sectional view of the anti-wafer penetration wax-free pad of the third embodiment of the present application;

[0031] Figure 6 It is a sectional exploded view of the anti-wafer penetration wax-free pad of the third embodiment of the present application;

[0032] Figure 7The exploded view of the adsorption pad and the protection pad connected according to the present application;

[0033] Figure 8 The schematic view of the protection pad according to the present application from the top.

[0034] In the figure: 1, the substrate disc; 11, the wafer placing groove; 12, the second annular clamping groove; 2, the adsorption pad; 21, the first annular clamping groove; 3, the protection pad; 31, the annular protection base layer; 32, the first annular clamping block; 33, the second annular clamping block. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0036] In order to solve the problem that the wafer is easy to slide from the wafer placing groove in the polishing process of the existing optical wafer, the wafer is not well protected, and the wax pad cannot be well used, please refer to Figures 1-8 The technical solutions are provided in the embodiments as follows:

[0037] Embodiment one

[0038] The wax pad for resisting wafer penetration in polishing of optical wafers comprises a substrate disc 1, an adsorption pad 2 and a protection pad 3. The substrate disc 1 is provided with a wafer placing groove 11 for placing a wafer. The wafer placing groove 11 is provided with the adsorption pad 2 for adsorbing the wafer. The adsorption pad 2 is clamped on the substrate disc 1 through the protection pad 3. The protection pad 3 is used for resisting wafer penetration and stabilizing the adsorption pad 2 on the substrate disc 1.

[0039] In the embodiment, the number of the wafer placing grooves 11 provided on the substrate disc 1 is one.

[0040] In the embodiment, the substrate disc 1 comprises the following raw materials in quality parts: iron powder 40 parts, silicon nitride powder 10 parts, niobium carbide powder 10 parts and binder 1 part.

[0041] In the embodiment, the adsorption pad 2 is made of polyurethane foaming material. The side end surface of the adsorption pad 2 is provided with the first annular clamping groove 21 for connecting the protection pad 3.

[0042] It should be noted that the adsorption pad 2 is connected with the protection pad 3 in interference by extruding the first annular clamping block 32 into the first annular clamping groove 21, so that the connection between the adsorption pad 2 and the protection pad 3 is stable.

[0043] In the embodiment, the protection pad 3 comprises a ring-shaped protection base layer 31, a first ring-shaped clamping block 32 and a second ring-shaped clamping block 33. The inner surface of the ring-shaped protection base layer 31 is provided with the first ring-shaped clamping block 32, and the outer surface of the ring-shaped protection base layer 31 is provided with the second ring-shaped clamping block 33.

[0044] It should be noted that the protection pad 3 is connected with the substrate disc 1 in interference by extruding the second ring-shaped clamping block 33 into the second ring-shaped clamping groove 12, so that the connection between the substrate disc 1 and the protection pad 3 is stable.

[0045] In the embodiment, the substrate disc 1 is provided with the second ring-shaped clamping groove 12 for connecting the protection pad 3. The second ring-shaped clamping groove 12 is matched with the second ring-shaped clamping block 33. The protection pad 3 is connected with the substrate disc 1 in interference by extruding the second ring-shaped clamping block 33 into the second ring-shaped clamping groove 12.

[0046] In the embodiment, the first ring-shaped clamping groove 21 is matched with the first ring-shaped clamping block 32. The adsorption pad 2 is connected with the protection pad 3 in interference by extruding the first ring-shaped clamping block 32 into the first ring-shaped clamping groove 21.

[0047] Specifically, by adding the protection pad 3 in the wafer placing groove 11, extruding the second ring-shaped clamping block 33 into the second ring-shaped clamping groove 12, and making the protection pad 3 assembled on the substrate disc 1, extruding the first ring-shaped clamping block 32 into the first ring-shaped clamping groove 21, and making the adsorption pad 2 assembled on the protection pad 3, and pressing the adsorption pad 2 tightly in the wafer placing groove 11, the wafer can be better protected by the protection pad 3, the wafer can be effectively prevented from being pierced, and the use effect of the wax-free pad can be improved.

[0048] In the embodiment, the ring-shaped protection base layer 31, the first ring-shaped clamping block 32 and the second ring-shaped clamping block 33 are integrally formed. The ring-shaped protection base layer 31, the first ring-shaped clamping block 32 and the second ring-shaped clamping block 33 all comprise the following raw materials in mass fraction: 20 parts of thermoplastic polyurethane elastomer, 22 parts of polyurethane fiber and 5 parts of auxiliary agent.

[0049] It should be noted that the thermoplastic polyurethane elastomer is also called thermoplastic polyurethane rubber, and is abbreviated as TPU. It is a (AB)n type block linear polymer, and has excellent comprehensive properties such as high strength, high toughness and wear resistance.

[0050] It should be noted that the polyurethane fiber is an elastic fiber. In addition to high strength, it also has high breaking elongation, low modulus and high elastic recovery rate.

[0051] Therefore, the thermoplastic polyurethane elastomer, the polyurethane fiber and the auxiliary agent are used to prepare the ring-shaped protection base layer 31, the first ring-shaped clamping block 32 and the second ring-shaped clamping block 33, so that the overall strength and wear resistance of the protection pad 3 are high, and the wafer can be prevented from being pierced.

[0052] In order to better show the preparation process of the wax-free pad for resisting wafer penetration in optical crystal wafer polishing, the embodiment provides a preparation process of the wax-free pad for resisting wafer penetration in optical crystal wafer polishing, which is used for preparing the wax-free pad for resisting wafer penetration in optical crystal wafer polishing as described above, and includes the following steps:

[0053] S1, preparing a substrate disc 1:

[0054] The iron powder, silicon nitride powder and niobium carbide powder are added into a mixing machine for uniform mixing, and then transferred into a ball mill for ball milling, with a ball-to-material ratio of 10:1, a ball milling speed of 300-400 r / min, and a ball milling time of 4-6 h. The mixed powder after ball milling is ground for 10-20 min, and then transferred into a vacuum drying box for drying for 3 h at a drying temperature of 100 ℃, to obtain dried mixed powder. The binder is added into the dried mixed powder, uniformly mixed, and then transferred into a forming mold for sintering forming. The formed substrate disc 1 is cooled at room temperature, and cooled to room temperature. The wafer placing groove 11 is processed on the substrate disc 1.

[0055] S2, preparing an adsorption pad 2:

[0056] The polyurethane foaming material is injection molded to form the adsorption pad 2. The first annular clamping groove 21 is processed on the side end face of the adsorption pad 2.

[0057] S3, preparing a protective pad 3:

[0058] The thermoplastic polyurethane elastomer, polyurethane fiber and auxiliary agent are uniformly mixed and melted, and then transferred into a forming mold for forming. After demolding, the integrally formed annular protective base layer 31, first annular clamping block 32 and second annular clamping block 33 are obtained.

[0059] S4, preparing a wax-free pad:

[0060] The second annular clamping block 33 is extruded into the second annular clamping groove 12, so that the protective pad 3 is assembled on the substrate disc 1. The first annular clamping block 32 is extruded into the first annular clamping groove 21, so that the adsorption pad 2 is assembled on the protective pad 3. The adsorption pad 2 is tightly pressed in the wafer placing groove 11. After assembly, the wax-free pad is formed.

[0061] Embodiment two

[0062] The wax-free pad for resisting wafer penetration in optical crystal wafer polishing includes a substrate disc 1, an adsorption pad 2 and a protective pad 3. The wafer placing groove 11 for placing a wafer is arranged on the substrate disc 1. The adsorption pad 2 for adsorbing the wafer is arranged in the wafer placing groove 11. The adsorption pad 2 is clamped on the substrate disc 1 through the protective pad 3. The protective pad 3 is used for resisting wafer penetration and stably fixing the adsorption pad 2 on the substrate disc 1.

[0063] In the embodiment, the number of wafer placing grooves 11 arranged on the substrate disc 1 is 3.

[0064] In the embodiment, the substrate disc 1 comprises the following raw materials in mass fraction: iron powder 40 parts, silicon nitride powder 10 parts, niobium carbide powder 10 parts and binder 1 part.

[0065] In the embodiment, the adsorption pad 2 is made of polyurethane foam material, and the side end surface of the adsorption pad 2 is provided with a first annular clamping groove 21 for connecting the protective pad 3.

[0066] In the embodiment, the protective pad 3 comprises an annular protective base layer 31, a first annular clamping block 32 and a second annular clamping block 33, the inner surface of the annular protective base layer 31 is provided with the first annular clamping block 32, and the outer surface of the annular protective base layer 31 is provided with the second annular clamping block 33.

[0067] In the embodiment, the substrate disc 1 is provided with a second annular clamping groove 12 for connecting the protective pad 3, the second annular clamping groove 12 and the second annular clamping block 33 are matched, and the protective pad 3 is connected with the substrate disc 1 in interference by extruding the second annular clamping block 33 into the second annular clamping groove 12.

[0068] In the embodiment, the first annular clamping groove 21 and the first annular clamping block 32 are matched, and the adsorption pad 2 is connected with the protective pad 3 in interference by extruding the first annular clamping block 32 into the first annular clamping groove 21.

[0069] In the embodiment, the annular protective base layer 31, the first annular clamping block 32 and the second annular clamping block 33 are integrally formed, and the annular protective base layer 31, the first annular clamping block 32 and the second annular clamping block 33 all comprise the following raw materials in mass fraction: thermoplastic polyurethane elastomer 20 parts, polyurethane fiber 22 parts and auxiliary agent 5 parts.

[0070] The wax-free pad is prepared by the same preparation method as in Embodiment One, and the difference between Embodiment Two and Embodiment One is that the number of wafer placing grooves 11 arranged on the substrate disc 1 in Embodiment Two is 3.

[0071] Embodiment Three

[0072] The wax-free pad for polishing optical crystal wafer is provided with the wafer placing groove 11 for placing the wafer, the adsorption pad 2 arranged in the wafer placing groove 11 for adsorbing the wafer, the adsorption pad 2 clamped on the substrate disc 1 by the protective pad 3, and the protective pad 3 for resisting wafer penetration and stabilizing the adsorption pad 2 on the substrate disc 1.

[0073] In the embodiment, the number of wafer placing grooves 11 arranged on the substrate disc 1 is 6.

[0074] In the embodiment, the substrate disc 1 comprises the following raw materials in mass fraction: iron powder 40 parts, silicon nitride powder 10 parts, niobium carbide powder 10 parts and binder 1 part.

[0075] In the embodiment, the adsorption pad 2 is made of polyurethane foam material, and the side end surface of the adsorption pad 2 is provided with a first annular clamping groove 21 for connecting the protective pad 3.

[0076] In the embodiment, the protective pad 3 comprises an annular protective base layer 31, a first annular clamping block 32 and a second annular clamping block 33, the inner surface of the annular protective base layer 31 is provided with the first annular clamping block 32, and the outer surface of the annular protective base layer 31 is provided with the second annular clamping block 33.

[0077] In the embodiment, the substrate disc 1 is provided with a second annular clamping groove 12 for connecting the protective pad 3, the second annular clamping groove 12 and the second annular clamping block 33 are matched, and the protective pad 3 is connected with the substrate disc 1 in interference by extruding the second annular clamping block 33 into the second annular clamping groove 12.

[0078] In the embodiment, the first annular clamping groove 21 and the first annular clamping block 32 are matched, and the adsorption pad 2 is connected with the protective pad 3 in interference by extruding the first annular clamping block 32 into the first annular clamping groove 21.

[0079] In the embodiment, the annular protective base layer 31, the first annular clamping block 32 and the second annular clamping block 33 are integrally formed, and the annular protective base layer 31, the first annular clamping block 32 and the second annular clamping block 33 all comprise the following raw materials in mass fraction: thermoplastic polyurethane elastomer 20 parts, polyurethane fiber 22 parts and auxiliary agent 5 parts.

[0080] The wax-free pad is prepared by the same preparation method as in Embodiment One, and the difference between Embodiment Two and Embodiment One is that the number of wafer placing grooves 11 provided on the substrate disc 1 in Embodiment Two is 6.

[0081] Comparative Example

[0082] The wax-free pad for polishing optical crystal wafer is provided with a substrate disc 1 and an adsorption pad 2, the substrate disc 1 is provided with a wafer placing groove 11 for placing a wafer, and the wafer placing groove 11 is provided with the adsorption pad 2 for adsorbing the wafer.

[0083] In the embodiment, the number of wafer placing grooves 11 provided on the substrate disc 1 is 1.

[0084] In the embodiment, the substrate disc 1 comprises the following raw materials in mass fraction: iron powder 40 parts, silicon nitride powder 10 parts, niobium carbide powder 10 parts and binder 1 part.

[0085] In the embodiment, the adsorption pad 2 is made of polyurethane foam material.

[0086] Compared with Example One, the protective pad 3 structure is cancelled in the comparative example, and the same preparation method as that of Example One is adopted to prepare the wax-free pad, and the preparation step of the protective pad 3 is cancelled accordingly.

[0087] The wax-free pads prepared in Examples 1-3 and the comparative example are subjected to performance testing, and the performance testing results of the wax-free pads are shown in Table 1:

[0088] Table 1: Performance testing results of the wax-free pads

[0089] Example 1 Example 2 Example 3 Comparative Example Protective pad / with, without Yes Yes Yes No Resistance to wafer penetration / 100% 98.68％ 98.68％ 98.68％ 86.35％

[0090] From the above table, it can be seen that the wax-free pads prepared in Examples One to Three can better resist wafer penetration.

[0091] Among them, the wafer penetration resistance of Example Two is unchanged compared with Example One, indicating that the number of wafer placement grooves provided on the substrate disc 1 is irrelevant to the wafer penetration resistance of the wax-free pad;

[0092] Among them, the wafer penetration resistance of Example Three is unchanged compared with Example One, indicating that the number of wafer placement grooves provided on the substrate disc 1 is irrelevant to the wafer penetration resistance of the wax-free pad;

[0093] Among them, the wafer penetration resistance of the comparative example is reduced compared with Example One, and since the protective pad 3 is not increased in the comparative example, the wafer penetration resistance of the wax-free pad is reduced, indicating that the protective pad 3 can improve the wafer penetration resistance of the wax-free pad.

[0094] Therefore, by additionally providing the protective pad 3 in the wafer placement groove 11, extruding the second annular clamping block 33 into the second annular clamping groove 12 to make the protective pad 3 assembled on the substrate disc 1, extruding the first annular clamping block 32 into the first annular clamping groove 21 to make the adsorption pad 2 assembled on the protective pad 3, and tightly pressing the adsorption pad 2 in the wafer placement groove 11, the wafer can be better protected by the protective pad 3, the wafer penetration can be effectively resisted, and the use effect of the wax-free pad is improved.

[0095] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0096] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A wax-free pad for polishing an optical crystal wafer and resisting wafer penetration, comprising a substrate plate (1), an adsorption pad (2) and a protective pad (3), characterized in that: The substrate disk (1) is provided with a wafer placement groove (11) for placing a wafer, and an adsorption pad (2) for adsorbing the wafer is provided in the wafer placement groove (11). The adsorption pad (2) is clamped on the substrate disk (1) through a protective pad (3). The protective pad (3) is used to prevent the wafer from penetrating and to secure the adsorption pad (2) on the substrate disk (1); The substrate disk (1) comprises the following raw materials in parts by mass: 40-60 parts of iron powder, 10-30 parts of silicon nitride powder, 10-20 parts of niobium carbide powder and 1-3 parts of a binder; The adsorption pad (2) is made of polyurethane foam material, and a side end surface of the adsorption pad (2) is provided with a first annular groove (21) for connecting to the protective pad (3); The protective pad (3) comprises an annular protective base layer (31), a first annular clamping block (32) and a second annular clamping block (33); the inner surface of the annular protective base layer (31) is provided with the first annular clamping block (32); the outer surface of the annular protective base layer (31) is provided with the second annular clamping block (33); the substrate disk (1) is provided with a second annular clamping groove (12) for connecting the protective pad (3); the second annular clamping groove (12) and the second annular clamping block (33) match each other; the protective pad (3) is interference-connected with the substrate disk (1) by squeezing the second annular clamping block (33) into the second annular clamping groove (12).

2. The wax-free pad for polishing an optical crystal piece to prevent chip penetration according to claim 1, characterized in that: The number of wafer placement slots (11) provided on the substrate disk (1) is 1, 3 or 6.

3. The wax-free pad for polishing an optical crystal piece to prevent chip penetration according to claim 2, wherein: The first annular groove (21) and the first annular block (32) match each other, and the adsorption pad (2) is interference-connected with the protective pad (3) by squeezing the first annular block (32) into the first annular groove (21).

4. The wax-free pad for polishing an optical crystal piece to prevent chip penetration according to claim 3, characterized in that: The annular protective base layer (31), the first annular clamping block (32) and the second annular clamping block (33) are integrally formed, and the annular protective base layer (31), the first annular clamping block (32) and the second annular clamping block (33) all comprise the following raw materials in parts by mass: 20-30 parts of thermoplastic polyurethane elastomer, 22-32 parts of polyurethane fiber and 5-16 parts of auxiliary agent.

5. A process for preparing a wax-free pad for polishing an optical crystal sheet and resisting wafer penetration, which is used to prepare the wax-free pad for polishing an optical crystal sheet and resisting wafer penetration as claimed in claim 4, characterized in that: The steps include: S1. Preparation of substrate disk (1): Add iron powder, silicon nitride powder and niobium carbide powder into a mixer and mix them uniformly, and transfer them into a ball mill for ball milling, with a ball-to-material ratio of 10:1, a ball milling speed of 300-400 r / min, and a ball milling time of 4-6 h. Grind the mixed powder after ball milling for 10-20 min, and transfer it into a vacuum drying oven for drying for 3 h at a drying temperature of 100° C. to obtain a dried mixed powder. Add a binder into the dried mixed powder, mix them uniformly, and transfer them into a forming mold for sintering and forming. Cool the embryonic disc of the formed substrate disc (1) at room temperature and cool it to room temperature, and process a chip placement groove (11) on the embryonic disc of the substrate disc (1); S2. Preparation of adsorption pad (2): The polyurethane foam material is injection molded and demoulded to form an adsorption pad (2), and a first annular groove (21) is machined on the side end surface of the adsorption pad (2); S3. Preparation of protective pad (3): After the thermoplastic polyurethane elastomer, polyurethane fiber and additives are fully mixed and melted, they are transferred into a molding mold for molding, and after demoulding, an integrally molded annular protective base layer (31), a first annular clamping block (32) and a second annular clamping block (33) are obtained; S4. Preparation of wax-free pad: The second annular clamping block (33) is squeezed into the second annular clamping groove (12), so that the protective pad (3) is assembled on the substrate disk (1), and the first annular clamping block (32) is squeezed into the first annular clamping groove (21), so that the adsorption pad (2) is assembled on the protective pad (3), and the adsorption pad (2) is pressed tightly into the wafer placement groove (11). After the assembly is completed, a wax-free pad is formed.

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