Environmentally friendly substrate for optical filter and wafer cleaving sheet and preparation method thereof

Abstract

The present invention provides an environmentally friendly substrate for optical filters and wafer cleaving sheets and a preparation method thereof, and relates to the technical field of semiconductors. The environmentally friendly substrate polyolefin film of the present invention comprises a first surface layer and a second surface layer stacked in layers; wherein the first surface layer is mainly prepared from the following components: copolymerized polypropylene, a polypropylene-based elastomer, and a lubricant, and the second surface layer is mainly prepared from the following components: ethylene-vinyl acetate copolymer and high-pressure low-density polyethylene. The present invention solves the technical problems of poor quality stability of PVC protective films for wafer cleaving and environmental pollution during recycling and treatment, and achieves the technical effect that the wafer cleaving protective film can not only achieve the same performance as the PVC protective film, but also does not pollute the environment during recycling and treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductors, and in particular to an environmentally friendly substrate for a filter and a wafer cleaving sheet and a preparation method thereof. Background Art

[0002] Wafer refers to the silicon chip used to make silicon semiconductor integrated circuits. Various circuit component structures can be processed on the wafer. The surface with the circuit component structure is usually called the front side, and the opposite side is called the back side.

[0003] In the process of wafer processing, in order to meet various purposes, it is usually necessary to adhere the wafer to a wafer carrier frame. The wafer carrier frame includes a film frame and a film, the film is adhered to the film frame, the film has a certain tension, and the wafer is adhered to the film. When cutting a whole wafer, laser cutting is generally used instead of mechanical tool cutting, because the knife marks of mechanical tool cutting wafer are wide, while the knife marks of laser cutting are narrow, so laser cutting can improve the utilization rate of wafers; at the same time, mechanical tool cutting wafers will also produce debris, while laser cutting will not produce debris, so the cutting quality can be improved. However, the deeper the cutting depth of laser cutting, the greater the loss to the laser transmitter, so when using laser cutting wafers, generally the wafer is not cut through, but longitudinal cracks and transverse cracks are formed, and the wafer is cut into multiple block wafers, and then the block wafers are separated from each other by a splitting device. Because the laser cutting process does not completely cut through the wafer, it is necessary to add a wafer splitting operation step to break the wafer at the longitudinal scratch or transverse crack, and then separate it into multiple wafer blocks. The existing splitting operation is usually completed by a splitting machine.

[0004] At present, the film adhered to the stretching frame is generally a PVC film. The characteristic of PVC film is that it has a certain self-cleaning property and can meet the cleanliness requirements of wafer processing. At the same time, the PVC film has good longitudinal and transverse isotropy in mechanical properties. When splitting, it can ensure that the grains in the longitudinal and transverse directions are evenly stressed without corner collapse. Moreover, when the PVC film is coated with glue, the PVC material has a certain polarity and has good adhesion with the glue, so that when splitting, the small grains that are well split can be controlled so that they will not fly away.

[0005] However, the current PVC protective film for wafer splitting uses a lot of additives during production, resulting in poor quality stability. Most importantly, the PVC protective film will pollute the environment during subsequent recycling and processing, such as releasing carcinogenic gas hydrogen chloride. Therefore, in today's environment where environmental protection awareness is gradually becoming a social consensus, the application of PVC protective film in wafer processing is gradually being restricted by the market and customers. Therefore, there is an urgent need for a wafer splitting protective film that can not only achieve the same performance as PVC protective film, but also will not release harmful substances into the environment during subsequent recycling and incineration, which is beneficial to environmental protection.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] One of the purposes of the present invention is to provide a polyolefin film which has better quality stability, better longitudinal and transverse isotropy in mechanical properties, stronger adhesion with glue, and is pollution-free to the environment.

[0008] The second object of the present invention is to provide a method for preparing the polyolefin film, which has a simple process and a high quality rate.

[0009] A third object of the present invention is to provide a protective film for wafer splitting, which has the same advantages as the above-mentioned polyolefin film.

[0010] A fourth object of the present invention is to provide a method for preparing the protective film for wafer splitting, which has a simple process and a high quality rate.

[0011] A fifth object of the present invention is to provide an application of the polyolefin film.

[0012] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0013] In a first aspect, a polyolefin film comprises a first surface layer and a second surface layer which are stacked;

[0014] The first surface layer is mainly prepared from the following components:

[0015] Copolymer polypropylene, propylene-based elastomer and lubricant;

[0016] The second surface layer is mainly prepared from the following components:

[0017] Ethylene-vinyl acetate copolymer and high pressure low density polyethylene.

[0018] Furthermore, the first surface layer is mainly prepared from the following components by mass:

[0019] 30-75 parts of copolymerized polypropylene, 25-70 parts of propylene-based elastomer and 1-10 parts of lubricant.

[0020] Furthermore, the second surface layer is mainly prepared from the following components by mass:

[0021] 70-90 parts of ethylene-vinyl acetate copolymer and 10-30 parts of high-pressure low-density polyethylene.

[0022] Furthermore, the first surface layer is mainly prepared from the following components by mass:

[0023] 65 parts of copolymerized polypropylene, 30 parts of propylene-based elastomer and 5 parts of lubricant;

[0024] Preferably, the second surface layer is mainly prepared from the following components by mass:

[0025] 75 parts of ethylene-vinyl acetate copolymer and 25 parts of high-pressure low-density polyethylene.

[0026] Further, the thickness of the first surface layer is 50-100 microns, preferably 50-60 microns;

[0027] Preferably, the thickness of the second surface layer is 15-75 microns, preferably 30-40 microns.

[0028] In a second aspect, a method for preparing the polyolefin film comprises the following steps:

[0029] Mixing the components of the first surface layer to obtain a first surface layer material;

[0030] mixing the components of the second surface layer to obtain a second surface layer material;

[0031] The first surface layer material and the second surface layer material are tape-casted to obtain the polyolefin film.

[0032] In a third aspect, a protective film for wafer splitting includes a substrate layer and an adhesive layer;

[0033] The material of the substrate layer includes the polyolefin film;

[0034] Wherein, the adhesive layer is arranged on the second surface layer of the polyolefin film.

[0035] Furthermore, the thickness of the adhesive layer is 20-60 microns, preferably 20-30 microns.

[0036] In a fourth aspect, a method for preparing the protective film for wafer splitting comprises the following steps:

[0037] The adhesive is coated on the second surface layer of the polyolefin film to obtain the wafer splitting protective film.

[0038] A fifth aspect is an application of the polyolefin film described in any one of the above items in wafer or filter splitting.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] The polyolefin film provided by the present invention has a first surface layer in which copolymerized polypropylene can provide rigidity for the entire film substrate, propylene elastomer can improve the mechanical properties of copolymerized polypropylene, so that the copolymerized polypropylene provides rigidity while the substrate still has a certain toughness, and the slip agent can improve the slippery opening performance of the outer layer, facilitating the subsequent coating and unwinding operation; in the second surface layer, ethylene-vinyl acetate copolymer can provide polar functional groups so that its bonding effect with the adhesive layer can reach the expected level, and high-pressure low-density polyethylene and ethylene-vinyl acetate copolymer can improve the processing performance of the film process after being blended. Therefore, the two layers of materials in the polyolefin film of the present invention cooperate with each other, so that the polyolefin film has better quality stability, and has better isotropy in the longitudinal and transverse directions in mechanical properties, and has stronger bonding force with the adhesive, and most importantly, it can achieve the same performance as PVC film, and is pollution-free to the environment.

[0041] The method for preparing the polyolefin film provided by the invention has simple process, high quality rate and is suitable for factory production.

[0042] The wafer splitting protective film provided by the present invention has the same advantages as the above-mentioned polyolefin film, which will not be repeated here; the wafer splitting protective film provided by the present invention can perfectly replace the existing wafer splitting protective film based on polyvinyl chloride.

[0043] The method for preparing the protective film for wafer splitting provided by the invention has simple process and high quality rate.

[0044] The application of the polyolefin film provided by the present invention can effectively improve the effect after wafer processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A flow chart of the preparation of a polyolefin film provided in one embodiment of the present invention;

[0047] Figure 2 A schematic diagram of the structure of a protective film for wafer splitting provided in one embodiment of the present invention.

[0048] Icon: 1-first surface layer; 2-second surface layer; 3-adhesive layer. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] According to a first aspect of the present invention, there is provided a polyolefin film comprising a first surface layer and a second surface layer stacked;

[0051] Among them, the first surface layer is mainly prepared from the following components:

[0052] Copolymer polypropylene, propylene-based elastomer and lubricant;

[0053] The second surface layer is mainly made of the following components:

[0054] Ethylene-vinyl acetate copolymer and high pressure low density polyethylene.

[0055] In the first surface layer of the present invention, copolymerized polypropylene can provide rigidity for the entire film substrate, propylene elastomer can improve the mechanical properties of copolymerized polypropylene, so that the copolymerized polypropylene provides rigidity while the substrate still has a certain toughness, and the slip agent can improve the slippery opening performance of the outer layer, which is convenient for the subsequent coating and unwinding operation; in the second surface layer of the present invention, ethylene-vinyl acetate copolymer can provide polar functional groups so that its bonding effect with the adhesive layer can reach the expected effect, and high-pressure low-density polyethylene and ethylene-vinyl acetate copolymer can improve the processing performance of the film process after blending. Therefore, the polyolefin film with a double-layer structure provided by the present invention, the two layers of materials cooperate with each other, so that the polyolefin film has better quality stability, and the mechanical properties are better in the longitudinal and transverse isotropy, and the bonding force with the glue is stronger. The most important thing is that it can achieve the same performance as the PVC film, and it is pollution-free to the environment.

[0056] In a preferred embodiment, the first surface layer of the polyolefin film of the present invention is mainly prepared from the following components by mass:

[0057] 30-75 parts of copolymerized polypropylene, 25-70 parts of polypropylene-based elastomer and 1-10 parts of lubricant.

[0058] Among them, typical but non-limiting mass parts of copolymerized polypropylene are, for example, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, and 75 parts; typical but non-limiting mass parts of polypropylene-based elastomers are, for example, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, and 70 parts; typical but non-limiting mass parts of lubricants are, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts. The present invention does not particularly limit the lubricant, and it can be preferably a low-precipitation lubricant, for example, Guangdong Fosu low-precipitation lubricant ABSL002, but is not limited thereto.

[0059] In a preferred embodiment, the second surface layer of the polyolefin film of the present invention is mainly prepared from the following components by mass:

[0060] 70-90 parts of ethylene-vinyl acetate copolymer and 10-30 parts of high-pressure low-density polyethylene.

[0061] Among them, typical but non-limiting mass fractions of ethylene-vinyl acetate copolymer are, for example, 70 parts, 75 parts, 80 parts, 85 parts, and 90 parts; the content of vinyl acetate (VA) in ethylene-vinyl acetate copolymer is 5-20%, for example, it can be 5%, 8%, 10%, 13%, 15%, 18%, and 20%. The content of vinyl acetate (VA) in ethylene-vinyl acetate copolymer is within this range, which can better cooperate with high-pressure low-density polyethylene to improve the quality of the material; typical but non-limiting mass fractions of high-pressure low-density polyethylene are, for example, 10 parts, 15 parts, 20 parts, 25 parts, and 30 parts.

[0062] The raw material dosage of the polyolefin film two-layer structure material selected in the present invention can further improve the quality stability of the polyolefin film and the isotropy of the mechanical properties in the longitudinal and transverse directions, as well as the bonding strength with the glue, so that the polyolefin film can reach or even exceed the PVC film in the same performance.

[0063] In a preferred embodiment, the first surface layer of the polyolefin film of the present invention is mainly prepared from the following components by mass:

[0064] 65 parts of copolymerized polypropylene, 30 parts of propylene-based elastomer and 5 parts of lubricant;

[0065] The second surface layer of the polyolefin film is mainly prepared from the following components by mass:

[0066] 75 parts of ethylene-vinyl acetate copolymer and 25 parts of high-pressure low-density polyethylene.

[0067] The specific amount of raw materials of the two-layer structure material of the polyolefin film defined in the present invention can make the polyolefin film have excellent quality stability and excellent longitudinal and transverse isotropy in mechanical properties, as well as high bonding strength with glue, so that the polyolefin film can reach or even exceed PVC film in the same performance.

[0068] In a preferred embodiment, the thickness of the first surface layer of the polyolefin film of the present invention is 50-100 microns, for example, it can be 50 microns, 55 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, and preferably 50-60 microns; the thickness of the second surface layer of the polyolefin film of the present invention is 15-75 microns, for example, it can be 15 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 75 microns, and preferably 30-40 microns.

[0069] The thickness of the first surface layer and the thickness of the second surface layer of the polyolefin film defined in the present invention can further improve the quality stability and the isotropy of the mechanical properties of the polyolefin film in the longitudinal and transverse directions.

[0070] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned polyolefin film, comprising the following steps:

[0071] Mixing the components of the first surface layer to obtain a first surface layer material;

[0072] mixing the components of the second surface layer to obtain a second surface layer material;

[0073] The first surface layer material and the second surface layer material are tape-cast to obtain a polyolefin film.

[0074] The method for preparing the polyolefin film provided by the invention has simple process, high quality rate and is suitable for factory production.

[0075] A typical method for preparing polyolefin film, the process flow is shown in Figure 1 , including the following steps:

[0076] The component materials of the first surface layer and the second surface layer are respectively mixed in proportion and fully stirred, and then poured into the hopper of the cast film extruder respectively, and after being plasticized, filtered and dispensed by the extruder, the two streams of melts merge into the die cavity, and then flow out from the die slit to the iron roller for rapid cooling and forming, thereby obtaining a polyolefin film;

[0077] A. Prepare materials: mix the components of the first surface layer to obtain the first surface layer material; mix the components of the second surface layer to obtain the second surface layer material;

[0078] B. Double-layer co-extrusion casting production: Nantong Sanxin SDLZ / CPO-1700 casting machine is used for production. The prepared first surface layer material and the second surface layer material are placed in their respective extruder hoppers, wherein the temperatures of the extruder zones 1-3 are set to 195°C, 210°C, and 220°C, respectively, and the temperatures of the other zones and the die head are set to 240°C; the die head (American Cororene die head) is a hanger-type co-extrusion die head, and the melts of the first surface layer material and the second surface layer material are cast onto a cooling iron roller through the die head to be cooled and formed, and then pulled through steel roller embossing (post-embossing process), corona device, and winding mechanism to finally be rolled into a roll-shaped substrate original film to obtain a polyolefin film;

[0079] Among them, the post-embossing process includes: after the melt is cooled and shaped by the quench roller, it is heated again to 35-75℃ and then embossed by a precision steel roller. On the one hand, the post-embossing process can make the first surface layer of the polyolefin film have a matte texture, which is conducive to the exhaust between the stacked layers of the rolled film and ensures the quality of the roll; on the other hand, the post-embossing process can also play the role of tempering treatment to eliminate the internal stress of the film while embossing, so that the obtained polyolefin film has better dimensional stability as a substrate in the subsequent gluing process.

[0080] It can be seen that the preparation method of the polyolefin film provided by the present invention has a simple process, a high quality rate, and is suitable for factory production. The polyolefin film obtained by the preparation method of the present invention has the characteristics of high quality stability and good isotropy of mechanical properties in the longitudinal and transverse directions.

[0081] According to a third aspect of the present invention, a protective film for wafer splitting is provided, comprising a substrate layer and an adhesive layer; wherein the substrate layer comprises the polyolefin film described in any one of the above items, and the adhesive layer is laminated on the second surface layer of the polyolefin film.

[0082] The present invention provides a protective film for wafer splitting, wherein the first surface layer of the polyolefin film as the substrate layer is a non-adhesive surface layer, and the second surface layer is an adhesive surface layer, and the adhesive layer is stacked on the adhesive surface layer of the polyolefin film, and the bonding effect between the two is better.

[0083] The wafer splitting protective film provided by the present invention has the same advantages as the above-mentioned polyolefin film, which will not be repeated here; the wafer splitting protective film provided by the present invention can perfectly replace the existing wafer splitting protective film based on polyvinyl chloride.

[0084] In the present invention, the thickness of the adhesive layer may be 20-60 microns, for example, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, preferably 20-30 microns.

[0085] The thickness of the adhesive layer selected by the present invention is beneficial to improving the comprehensive performance of the protective film for wafer splitting.

[0086] A typical protective film for wafer splitting, the structure is as follows Figure 2 As shown, it includes a substrate layer polyolefin film (the polyolefin film includes a first surface layer 1, a second surface layer 2) and an adhesive layer 3;

[0087] Wherein, the adhesive layer 3 is laminated on the second surface layer 2 of the polyolefin film;

[0088] The substrate layer polyolefin film is a double-layer co-extruded cast film structure. The first surface layer 1 (non-adhesive surface layer) of the polyolefin film is mainly made of copolymerized polypropylene, polypropylene-based elastomer and lubricant, and has certain rigidity and good mechanical properties; the second surface layer 2 (adhesive surface layer) of the polyolefin film is mainly made of ethylene-vinyl acetate copolymer and high-pressure low-density polyethylene, which can achieve a better bonding effect with the adhesive to form a bonding layer 3.

[0089] The wafer splitting protective film provided by the present invention has high quality stability and better longitudinal and transverse isotropy in mechanical properties, and can reach or even exceed PVC film in the same performance, so it can perfectly replace the existing wafer splitting protective film based on polyvinyl chloride.

[0090] According to a fourth aspect of the present invention, there is provided a method for preparing a protective film for wafer splitting as described in any one of the above, comprising the following steps:

[0091] The adhesive is coated on the second surface layer of the polyolefin film to obtain a protective film for wafer splitting.

[0092] The method for preparing the protective film for wafer splitting provided by the present invention has simple process, high quality rate and is suitable for factory production.

[0093] A typical method for preparing a protective film for wafer splitting includes the following steps:

[0094] A single-sided release PET film is used for transfer coating, and a filling adhesive layer is coated on the second surface layer of the polyolefin film through a coating process to form an adhesive layer to obtain a protective film for wafer splitting.

[0095] The method for preparing the protective film for wafer splitting provided by the present invention has simple process, easy operation and high excellent rate.

[0096] According to a fifth aspect of the present invention, there is provided a use of any of the above-mentioned polyolefin films in wafer or filter splitting, which can effectively improve the effect after wafer processing.

[0097] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0098] Example 1

[0099] A polyolefin film comprises a first surface layer and a second surface layer which are stacked;

[0100] The first surface layer is mainly prepared from the following components by mass:

[0101] 65 parts of copolymerized polypropylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, the polypropylene-based elastomer is Exxon Chemical elastomer 3980FL, and the lubricant is Guangdong Fosu low precipitation lubricant ABSL002;

[0102] The second surface layer is mainly prepared from the following components by mass:

[0103] 75 parts of ethylene-vinyl acetate copolymer and 25 parts of high-pressure low-density polyethylene; the ethylene-vinyl acetate copolymer is Hanwha ethylene-vinyl acetate copolymer 1826, and the high-pressure low-density polyethylene is DuPont Chemical high-pressure low-density polyethylene 450E.

[0104] Example 2

[0105] A polyolefin film comprises a first surface layer and a second surface layer which are stacked;

[0106] The first surface layer is mainly prepared from the following components by mass:

[0107] 65 parts of copolymerized polypropylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; the copolymerized polypropylene is French Total TF430, the polypropylene-based elastomer is Exxon Chemical Elastomer 3980FL, and the lubricant is Guangdong Fosu Low Separation Lubricant ABSL002;

[0108] The second surface layer is mainly prepared from the following components by mass:

[0109] 75 parts of ethylene-vinyl acetate copolymer and 25 parts of high-pressure low-density polyethylene; the ethylene-vinyl acetate copolymer is Hanhua ethylene-vinyl acetate copolymer 1826, and the high-pressure low-density polyethylene is Jiangsu Yangzi BASF Mao high-pressure low-density polyethylene 2426K.

[0110] Example 3

[0111] Compared with Example 1, the first surface layer of the polyolefin film of this embodiment is mainly prepared from the following components by mass:

[0112] 75 parts of copolymerized polypropylene (Shanghai Petrochemical F280B), 25 parts of polypropylene-based elastomer (Exxon Chemical Elastomer 3980FL) and 3 parts of lubricant (Guangdong Fosu Low Separation ABSL002).

[0113] The rest of the process was the same as in Example 1 to obtain a polyolefin film.

[0114] Example 4

[0115] Compared with Example 1, the first surface layer of the polyolefin film of this embodiment is mainly prepared from the following components by mass:

[0116] 50 parts of copolymerized polypropylene (Shanghai Petrochemical F280B), 50 parts of polypropylene-based elastomer (Exxon Chemical Elastomer 3980FL) and 3 parts of lubricant (Guangdong Fosu Low Precipitation ABSL002);

[0117] The rest of the process was the same as in Example 1 to obtain a polyolefin film.

[0118] Example 5

[0119] Compared with Example 1, the first surface layer of the polyolefin film of this embodiment is mainly prepared from the following components by mass:

[0120] 30 parts of copolymerized polypropylene (Shanghai Petrochemical F280B), 70 parts of polypropylene-based elastomer (Exxon Chemical Elastomer 3980FL) and 3 parts of lubricant (Guangdong Fosu Low Precipitation ABSL002);

[0121] The rest of the process was the same as in Example 1 to obtain a polyolefin film.

[0122] Example 6

[0123] Compared with Example 1, the second surface layer of the polyolefin film of this embodiment is mainly prepared from the following components by mass:

[0124] 90 parts of ethylene-vinyl acetate copolymer (Hanhua 1826) and 10 parts of high pressure low density polyethylene (DuPont Chemical 450E);

[0125] The rest of the process was the same as in Example 1 to obtain a polyolefin film.

[0126] Example 7

[0127] Compared with Example 1, the second surface layer of the polyolefin film of this embodiment is mainly prepared from the following components by mass:

[0128] 70 parts of ethylene-vinyl acetate copolymer (Hanhua 1826) and 30 parts of high-pressure low-density polyethylene (DuPont Chemical 450E);

[0129] The rest of the process was the same as in Example 1 to obtain a polyolefin film.

[0130] Example 8

[0131] This embodiment is a method for preparing the polyolefin film of Embodiment 1-7, comprising the following steps:

[0132] A. Prepare materials: mix the components of the first surface layer to obtain the first surface layer material; mix the components of the second surface layer to obtain the second surface layer material;

[0133] B. Double-layer co-extrusion casting production: Nantong Sanxin SDLZ / CPO-1700 casting machine is used for production. The prepared first surface layer material and the second surface layer material are placed in their respective extruder hoppers, wherein the temperatures of the extruder zones 1-3 are set to 195°C, 210°C, and 220°C, respectively, and the temperatures of the other zones and the die head are set to 240°C; the die head (American Cologne die head) is a hanger-type co-extrusion die head, and the melts of the first surface layer material and the second surface layer material are cast onto a cooling iron roller through the die head for cooling and forming, and then are respectively traction-driven through steel roller embossing (post-embossing process), corona device, and winding mechanism to finally be rolled into a roll-shaped substrate original film to obtain a polyolefin film; the first surface layer thickness of the polyolefin film is 50 microns, and the second surface layer thickness is 40 microns;

[0134] Post-embossing processes include:

[0135] After the melt of the material is cooled and shaped by the quench roller, it is heated again by 35-75℃ and then embossed by the precision steel roller. On the one hand, the post-embossing process can make the first surface layer of the polyolefin film have a matte texture, which is conducive to the exhaust between the stacked layers of the rolled film and ensures the quality of the roll; on the other hand, the post-embossing process can also play the role of tempering treatment to eliminate the internal stress of the film while embossing, so that the obtained polyolefin film has better dimensional stability as a substrate in the subsequent gluing process.

[0136] Examples 9-15

[0137] Embodiments 9-15 provide a protective film for wafer splitting, which is formed by laminating a substrate layer and an adhesive layer;

[0138] The substrate layers of the wafer splitting protective films of Examples 9 to 15 are the polyolefin films provided in Examples 1 to 7, respectively. The adhesive layer is laminated on the second surface layer of the polyolefin film, and the thickness of the adhesive layer is 20 microns.

[0139] Example 16

[0140] This embodiment is a method for preparing the protective film for wafer splitting of Embodiments 9-15, comprising the following steps:

[0141] A single-sided release PET film with a thickness of 0.05 mm was used for transfer coating, and a filling adhesive layer was coated on the second surface layer of the polyolefin film through a coating process using a Taicang Guangsheng high-precision coating machine (the adhesive layer glue was HS-1060 produced by Guangzhou Huisheng Technology Co., Ltd.), and the coating dry glue thickness was 20 microns to form an adhesive layer to obtain a protective film for wafer splitting.

[0142] Comparative Example 1

[0143] Compared with the polyolefin film of Example 1, the raw materials for preparing the first surface layer of the polyolefin film of this comparative example do not contain copolymerized polypropylene and polypropylene-based elastomer, and the first surface layer is mainly prepared from the following components in parts by mass:

[0144] 95 parts of high-density polyethylene and 5 parts of lubricant; the high-density polyethylene is HDPE8008 from Dushanzi Petrochemical, and the lubricant is Guangdong Fosu low-precipitation lubricant ABSL002;

[0145] The second surface layer is the same as that in Example 1, and the preparation method is the same as that in Example 1 to obtain a polyolefin film.

[0146] Comparative Example 2

[0147] Compared with the polyolefin film of Example 1, the raw material for preparing the first surface layer of the polyolefin film of this comparative example replaces copolymerized polypropylene with an equal amount of high-density polyethylene, and the first surface layer is mainly prepared from the following components by mass:

[0148] 65 parts of high-density polyethylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; the high-density polyethylene is HDPE8008 from Dushanzi Petrochemical, the polypropylene-based elastomer is Exxon Chemical Elastomer 3980FL, and the lubricant is Guangdong Fosu Low Separation Lubricant ABSL002;

[0149] The second surface layer is the same as that in Example 1, and the preparation method is the same as that in Example 1 to obtain a polyolefin film.

[0150] Comparative Example 3

[0151] Compared with the polyolefin film of Example 1, the raw materials for preparing the first surface layer of the polyolefin film of this comparative example do not contain a polypropylene-based elastomer, and the first surface layer is mainly prepared from the following components by mass:

[0152] 95 parts of copolymerized polypropylene and 5 parts of lubricant; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, and the lubricant is Guangdong Fosu low precipitation lubricant ABSL002;

[0153] The second surface layer is the same as that in Example 1, and the preparation method is the same as that in Example 1 to obtain a polyolefin film.

[0154] Comparative Example 4

[0155] Compared with the polyolefin film of Example 1, the raw material for preparing the first surface layer of the polyolefin film of this comparative example replaces the polypropylene-based elastomer with an equal amount of vinyl elastomer, and the first surface layer is mainly prepared from the following components in parts by mass:

[0156] 65 parts of copolymerized polypropylene, 30 parts of vinyl elastomer and 5 parts of lubricant; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, the vinyl elastomer is American Dow 7387, and the lubricant is Guangdong Fosu low precipitation lubricant ABSL002;

[0157] The second surface layer is the same as that in Example 1, and the preparation method is the same as that in Example 1 to obtain a polyolefin film.

[0158] Comparative Example 5

[0159] Compared with the polyolefin film of Example 1, the raw materials for preparing the first surface layer of the polyolefin film of this comparative example do not contain a lubricant, and the first surface layer is mainly prepared from the following components by mass:

[0160] 65 parts of copolymerized polypropylene and 35 parts of polypropylene-based elastomer; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, and the polypropylene-based elastomer is Exxon Chemical Elastomer 3980FL;

[0161] The second surface layer is the same as that in Example 1, and the preparation method is the same as that in Example 1 to obtain a polyolefin film.

[0162] Comparative Example 6

[0163] Compared with the polyolefin film of Example 1, the raw materials for preparing the second surface layer of the polyolefin film of this comparative example do not contain ethylene-vinyl acetate copolymer, specifically:

[0164] The first surface layer is mainly prepared from the following components by mass:

[0165] 65 parts of copolymerized polypropylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, the polypropylene-based elastomer is Exxon Chemical elastomer 3980FL, and the lubricant is Guangdong Fosu low precipitation lubricant ABSL002;

[0166] The second surface layer is mainly prepared from the following components by mass:

[0167] 100 parts of high-pressure low-density polyethylene; the high-pressure low-density polyethylene is DuPont Chemical high-pressure low-density polyethylene 450E;

[0168] The preparation method is the same as that of Example 1 to obtain a polyolefin film.

[0169] Comparative Example 7

[0170] Compared with the polyolefin film of Example 1, the raw material for preparing the second surface layer of the polyolefin film of this comparative example is replaced by an equal amount of vinyl elastomer with ethylene-vinyl acetate copolymer, specifically:

[0171] The first surface layer is mainly prepared from the following components by mass:

[0172] 65 parts of copolymerized polypropylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, the polypropylene-based elastomer is Exxon Chemical elastomer 3980FL, and the lubricant is Guangdong Fosu low precipitation lubricant ABSL002;

[0173] The second surface layer is mainly prepared from the following components by mass:

[0174] 75 parts of vinyl elastomer and 25 parts of high-pressure low-density polyethylene; the vinyl elastomer is American DuPont 7387, and the high-pressure low-density polyethylene is DuPont Chemical High-Pressure Low-Density Polyethylene 450E;

[0175] The preparation method is the same as that of Example 1 to obtain a polyolefin film.

[0176] Comparative Example 8

[0177] Compared with the polyolefin film of Example 1, the raw materials for preparing the second surface layer of the polyolefin film of this comparative example do not contain high-pressure low-density polyethylene, specifically:

[0178] The first surface layer is mainly prepared from the following components by mass:

[0179] 65 parts of copolymerized polypropylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, the polypropylene-based elastomer is Exxon Chemical elastomer 3980FL, and the lubricant is Guangdong Fosu low precipitation lubricant ABSL002;

[0180] The second surface layer is mainly prepared from the following components by mass:

[0181] 100 parts of ethylene-vinyl acetate copolymer; the ethylene-vinyl acetate copolymer is Hanhua ethylene-vinyl acetate copolymer 1826;

[0182] The preparation method is the same as that of Example 1 to obtain a polyolefin film.

[0183] Comparative Example 9

[0184] Compared with the polyolefin film of Example 1, the raw materials for preparing the second surface layer of the polyolefin film of this comparative example are replaced by an equal amount of low-pressure high-density polyethylene to replace high-pressure low-density polyethylene, and an equal amount of vinyl elastomer to replace ethylene-vinyl acetate copolymer, specifically:

[0185] The first surface layer is mainly prepared from the following components by mass:

[0186] 65 parts of copolymerized polypropylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; the copolymerized polypropylene is Shanghai Petrochemical copolymerized polypropylene F280B, the polypropylene-based elastomer is Exxon Chemical elastomer 3980FL, and the lubricant is Guangdong Fosu low precipitation lubricant ABSL002;

[0187] The second surface layer is mainly prepared from the following components by mass:

[0188] 75 parts of vinyl elastomer and 25 parts of low-pressure high-density polyethylene; the vinyl elastomer is DuPont 7387 from the United States, and the low-pressure high-density polyethylene is HDPE8008 from Dushanzi Petrochemical;

[0189] The preparation method is the same as that of Example 1 to obtain a polyolefin film.

[0190] Comparative Example 10

[0191] Compared with the polyolefin film of Example 1, the polyolefin film of this comparative example is only the second surface layer and does not contain the first surface layer. The second surface layer is mainly prepared from the following components by mass:

[0192] 75 parts of vinyl elastomer and 25 parts of high-pressure low-density polyethylene; the vinyl elastomer is American DuPont 7387, and the high-pressure low-density polyethylene is DuPont Chemical High-Pressure Low-Density Polyethylene 450E;

[0193] The preparation method is the same as that of Example 1 to obtain a polyolefin film.

[0194] Comparative Examples 11-20

[0195] Comparative Examples 11-20 provide a protective film for wafer splitting, which is formed by laminating a substrate layer and an adhesive layer;

[0196] The substrate layers of the wafer splitting protective films of Comparative Examples 11-20 are the polyolefin films provided in Comparative Examples 1-10, respectively. The adhesive layer is laminated on the second surface layer of the polyolefin film. The thickness of the adhesive layer is 20 microns. The preparation method is the same as that of Example 16 to obtain a wafer splitting protective film.

[0197] Comparative Example 21

[0198] The PVC protective film for wafer cracking currently on the market is Dongxu TH95C.

[0199] Comparative Example 22

[0200] The PVC protective film for wafer cracking currently on the market is Dongxu TH100C.

[0201] Test example

[0202] The performance tests were conducted on the wafer splitting protective films provided in Examples 9-15 and Comparative Examples 16-22. The test standards and methods are as follows. The results are shown in Table 1.

[0203] Grid knife test standard: ASTM D3359;

[0204] Test method: After the coating process of the splinter protective film is completed, take a piece of the protective film and scratch it with a grid knife. At the same time, use the same type of unscratched tape to stick it to the scratched tape, and then evaluate it according to the standard ASTM D3359.

[0205] Evaluation test of protective film for chipping: A protective film for chipping was pasted on one side of a 12-inch Si mirror wafer (thickness: 25 μm) under the following conditions:

[0206] 1) Cut the back grinding tape from the surface opposite to the adhesive surface to obtain 593 small pieces of 10.5 mm × 10.5 mm;

[0207] 2) Cut the wafer using the laser invisible cutting method with a cutting depth of 15 μm;

[0208] 3) Put the cut wafer into a wafer splitting machine for splitting;

[0209] 4) The flying material of the wafers that have been split is counted a(%); the longitudinal and transverse cutting line spacing is tested and the resin Lx (lateral cutting line spacing) and Ly (longitudinal cutting line spacing) are read under a microscope.

[0210] Table 1

[0211]

[0212] It can be seen from the data in Table 1 that the wafer splitting protective film provided by Examples 9-10 of the present invention can achieve the same level as the PVC splitting protective film (Comparative Examples 21-22) in terms of friction coefficient and flying material percentage, and is superior to the performance of the PVC splitting protective film (Comparative Examples 21-22) in terms of longitudinal and transverse uniformity and hundred-grid knife tests; at the same time, the comprehensive performance of the wafer splitting protective film provided by Examples 9-15 of the present invention is also superior to the wafer splitting protective film provided by other comparative examples.

[0213] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyolefin film, characterized in that: It includes a first surface layer and a second surface layer which are stacked; The first surface layer is prepared from the following components by mass: 65 parts of copolymerized polypropylene, 30 parts of polypropylene-based elastomer and 5 parts of lubricant; The second surface layer is prepared from the following components by mass: 75 parts of ethylene-vinyl acetate copolymer and 25 parts of high-pressure low-density polyethylene.

2. The polyolefin film according to claim 1, characterized in that The thickness of the first surface layer is 50-100 microns.

3. The polyolefin film according to claim 2, characterized in that: The thickness of the first surface layer is 50-60 microns.

4. The polyolefin film according to claim 1, characterized in that: The thickness of the second surface layer is 15-75 microns.

5. The polyolefin film according to claim 4, characterized in that: The thickness of the second surface layer is 30-40 microns.

6. A method for preparing a polyolefin film according to any one of claims 1 to 5, characterized in that: The following steps are involved: Mixing the components of the first surface layer to obtain a first surface layer material; mixing the components of the second surface layer to obtain a second surface layer material; The first surface layer material and the second surface layer material are tape-casted to obtain the polyolefin film.

7. A protective film for wafer splitting, characterized in that: It includes a substrate layer and an adhesive layer; The material of the substrate layer comprises the polyolefin film according to any one of claims 1 to 5; Wherein, the adhesive layer is arranged on the second surface layer of the polyolefin film.

8. The wafer splitting protective film according to claim 7, characterized in that: The thickness of the adhesive layer is 20-60 microns.

9. The wafer splitting protective film according to claim 8, characterized in that: The thickness of the adhesive layer is 20-30 microns.

10. A method for preparing a protective film for wafer splitting according to any one of claims 7 to 9, characterized in that: The following steps are involved: The adhesive is coated on the second surface layer of the polyolefin film to obtain the wafer splitting protective film.

11. Use of the polyolefin film according to any one of claims 1 to 5 in wafer or filter splitting.

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