TWI704205B - Cutting sheet and manufacturing method of cutting sheet - Google Patents

Abstract

The present invention relates to a dicing sheet and a method of manufacturing a dicing sheet, wherein, as the dicing sheet 1 having a substrate film 2 and a single-area adhesive layer 3 of the substrate film 2, the substrate film 2 has at least a distance between The resin layer 21 at the nearest portion of the adhesive layer 3 has a melting point of 60°C or more and 170°C or less of the resin constituting the resin layer 21, and the difference between the resin melting point and the fluidization temperature is 40°C or more and 190°C or less. Such a cutting blade 1 can be manufactured without radiation, and it can also suppress the generation of filamentary cutting blades and exhibit good expandability.

Description

Cutting sheet and manufacturing method of cutting sheet

The present invention relates to a dicing sheet and a manufacturing method of the dicing sheet, in particular to a cutting sheet to which the cut object is pasted when the semiconductor wafer is cut and separated into component blocks, and the manufacturing method of the dicing sheet .

Semiconductor wafers such as polysilicon oxide and gallium arsenide, glass substrates, alumina substrates and other substrates, as well as various packaging products (collectively referred to as "cut objects" in the patent description of the present invention) are manufactured in a large diameter state. When the component blocks (referred to as "chips" in the patent specification of the present invention) are cut and separated (diced), they are individually peeled off (pick up) and then moved to the next process and adhesion process. At this time, the to-be-cut objects such as semiconductor wafers are moved to various processes such as dicing, washing, drying, expansion, picking, and bonding in a state where they are attached to the adhesive sheet in advance.

The cut object moved to the above-mentioned cutting process. In order to ensure the proper positioning of the cut object and the wafer in the cutting process and the subsequent process, the cutting sheet is attached to the surface of the cut object that is in contact with the cutting tool for cutting in advance. On the opposite surface, such a dicing sheet is usually used as a base film, and a polyolefin-based film or a polyvinyl chloride-based film can be used to form an adhesive layer on the base film.

As a specific method of the cutting process, in general full cutting, a rotating round knife is used to cut the to-be-cut object. At this time, the cutting piece can cut the object to be cut and glued, not only the object-to-be-cut. , Even the adhesive layer will be cut In addition, sometimes a part of the base film is also cut.

At this time, the cutting chips formed by the materials constituting the adhesive layer and the base film are produced on the cutting chips, and sometimes the obtained chips are contaminated by the cutting chips. One type of this kind of cutting chips is Filament cutting chips are attached to the cutting line or near the cross section of the wafer separated by cutting.

If a large number of the same wire-shaped cutting chips as above are attached to the wafer and the wafer is sealed, the wire-shaped cutting chips attached to the wafer will be decomposed by the heat of the sealing, and this thermal decomposition product will damage the package or cause a malfunction in the obtained device s reason. Since the wire-shaped cutting chips are difficult to be removed by washing, the production of the wire-shaped cutting chips will reduce the productivity of the cutting process. Therefore, in the case of cutting with the cutting chips, it is required to prevent the production of the wire-shaped cutting chips.

In addition, when a plurality of wafers are diced with a package sealed with a hardened resin as the to-be-cut object, compared with the case of dicing semiconductor wafers, the dicing blade used has a larger cutting width and a deeper cutting depth. Therefore, since the amount of substrate film cut off during dicing is more than that in the case of dicing semiconductor wafers, the amount of wire-like cutting chips produced also increases.

In order to suppress the generation of such cutting chips, Patent Document 1 discloses the invention of a polyolefin-based film that is irradiated with electron beams or γ (gamma) rays from 1 to 80 Mrad as a base film of the cutting chips. In this invention, the inventor believes that the resin constituting the base film by irradiation of electron beams or gamma rays can form a bridge through covalent bonding, thereby suppressing the generation of cutting chips.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 5-211234

However, in the invention of Patent Document 1, since the irradiation of electron beams or γ-rays and other radiation rays requires the same resin as the above to be formed into a thin film state, an additional manufacturing process is required, and the manufacturing cost is more than that of a general base film. expensive. In addition, in the case of electron beam irradiation, the resin crystallinity in the base film is lost, and the solvent resistance of the obtained base film is relatively low.

In addition, when the aforementioned expansion process is performed, the dicing sheet is required to have good expandability. Because the same radiation irradiation as described in Patent Document 1 is used here, the covalently bonded substrate film forming the bridge exhibits a high Because of the elastic modulus, the dicing sheet described in Patent Document 1 cannot exhibit sufficient expandability.

The present invention has been completed in view of the above-mentioned problems, and its object is to provide a dicing sheet that can be manufactured without radiation irradiation, can suppress the generation of filamentary cutting chips, and exhibits good expandability.

In order to achieve the above object, first, the present invention provides a dicing sheet having a base film and an adhesive layer laminated on one side of the base film (Invention 1), characterized in that the base film has at least The resin layer of the portion closest to the adhesive layer has a melting point of 60°C or higher and 170°C or lower, and the difference between the resin melting point and the fluidization temperature is 40°C or higher and 190°C or lower.

The above-mentioned invention (Invention 1) relates to the dicing sheet, the melting point of the resin constituting the base film and the temperature difference between the melting point and the fluidization temperature are within the above range Inside, even if frictional heat is generated due to cutting, it is difficult to cause resin fluidization. Here, the wire-shaped cutting blade is softened by the frictional heat generated during cutting, and in addition, it is also elongated into a wire shape. Therefore, as a result of making it difficult to produce resin fluidization on the cutting chip, the generation of the wire cutting chip can be suppressed. In addition, since the elastic modulus of the base film whose resin melting point and the above-mentioned temperature difference are within the above-mentioned range becomes relatively low, it can exhibit good expandability. In addition, the base film whose resin melting point and the above-mentioned temperature difference are within the above-mentioned range can be produced without irradiation with radiation such as electron beams or gamma rays. Therefore, the dicing sheet is produced by a method including a process involving irradiation of radiation. Compared with the cutting sheet, the manufacturing cost can be reduced.

In the above invention (Invention 1), it is preferable that the resin includes a plurality of molecular chains as a constituent of the olefin, and the molecular chains are dynamically covalently bonded to each other depending on the temperature dependency to be linked (Invention 2).

In the above invention (Invention 2), the molecular chain system includes as a structural unit an ethylene copolymer of ethylene and a base polymerizable acid anhydride, the resin further has a polyvalent alcohol compound having two or more hydroxyl groups, and the temperature dependence is dynamically co-operated. The valence bond system is preferably an ester linkage formed between the carboxyl group derived from the above-mentioned group-polymerizable acid anhydride and the hydroxyl group of the above-mentioned polyvalent alcohol compound (Invention 3).

In the above inventions (Inventions 2 and 3), the resin further preferably contains a reaction accelerator that promotes the temperature-dependent dynamic covalent bonding and dissociation reactions (Invention 4).

In the above inventions (Inventions 1 to 4), it is preferable that the tensile modulus of elasticity of the resin layer at 23°C is 30 MPa or more and 500 MPa or less (Invention 5).

In the above inventions (Inventions 1 to 5), the melt flow rate of the resin at a temperature of 190°C and a load of 2.16kg is 0.5g/10min or more and 10g/10min or less Better (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferable that the base film further has a second resin layer on the opposite side of the adhesive layer of the resin layer (Invention 7).

Second, the present invention provides a method for manufacturing the above-mentioned dicing sheet (Inventions 1 to 7), characterized by comprising a process of copolymerizing constituent units containing at least ethylene and a base polymerizable acid anhydride to obtain an ethylene-based copolymer, and In the presence of a reaction accelerator that promotes temperature-dependent dynamic covalent bonding and dissociation reactions, the carboxyl group derived from the polymerizable anhydride of the above-mentioned vinyl copolymer, and at least 2 hydroxyl groups in the molecule The process of obtaining the above-mentioned resin by making ester chains between the hydroxyl groups of the alcohol compound (Invention 8).

The cutting blades related to the present invention can be manufactured without irradiating radiation, can suppress the generation of filamentary cutting blades, and present good expandability.

1‧‧‧Cutting disc

2‧‧‧Substrate film

21‧‧‧Resin layer

22‧‧‧Second resin layer

3‧‧‧Adhesive layer

[Fig. 1] A cross-sectional view of the dicing sheet according to the first embodiment of the present invention.

[Figure 2] A cross-sectional view of a dicing sheet according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

1. Cutting sheet

Fig. 1 is a cross-sectional view of the cutting blade according to the first embodiment of the present invention, and Fig. 2 is a cross-sectional view of the cutting blade according to the second embodiment of the present invention. These dicing sheets 1 have a substrate film 2 and an adhesive layer 3 formed by a single-area layer of the substrate film 2. In addition, the dicing sheet related to this embodiment can be used for cutting only Chips can also be used for the cutting of grain bonding. The grains are flakes.

(1) Substrate film

In the dicing sheet 1 related to this embodiment, the base film 2 has at least a resin layer 21 located at the part closest to the adhesive layer 3. In particular, in the dicing sheet 1 shown in FIG. 1, the base film 2 only has a resin layer 21 formed. In addition, in the dicing sheet 1 shown in FIG. 2, the base film 2 has a resin layer 21 positioned closest to the adhesive layer 3 and a second resin layer 22 positioned on the opposite side of the adhesive layer 3 of the resin layer 21.

(1-1) Physical properties of resin layer

In the dicing sheet 1 according to this embodiment, the melting point of the resin constituting the resin layer 21 is 60° C. or more and 170° C. or less. In addition, the difference between the melting point of the resin and the fluidization temperature is 40°C or more and 190°C or less.

If the melting point of the resin layer 21 and the aforementioned temperature difference are within the aforementioned range, the fluidization temperature of the resin constituting the resin layer 21 can reach a sufficiently high temperature. Therefore, even if frictional heat is generated during cutting, fluidization of the resin constituting the resin layer 21 due to the frictional heat can be suppressed. As a result, the dicing sheet 1 according to the present embodiment can suppress the generation of filamentary cutting chips. In addition, since the melting point of the resin layer 21 and the above-mentioned temperature difference are within the above-mentioned range, the elastic modulus of the resin constituting the resin layer 21 becomes relatively low. Accordingly, the dicing sheet 1 according to this embodiment exhibits a good Expandability. In addition, the base film 2 in which the melting point of the resin layer 21 and the above-mentioned temperature difference are within the above-mentioned range can be produced without being irradiated with radioactive rays such as electron beams or gamma rays. Therefore, the dicing sheet 1 related to this embodiment and the transmission process including radiation irradiation Compared with the cutting sheet manufactured by the method, it can be manufactured at a lower cost.

In the dicing sheet 1 according to this embodiment, the melting point of the resin constituting the resin layer 21 is 60°C or higher as described above, preferably 70°C or higher, and more preferably 80°C the above. In addition, the melting point of the resin is 170°C or lower as described above, preferably 140°C or lower, and more preferably 120°C or lower. Since the melting point is above 60° C., the base film 1 will not wrinkle or stick to a roll, and the base film 1 can be efficiently obtained through extrusion molding. In addition, when the melting point of the resin constituting the resin layer 21 is 60° C. or higher, the resin has appropriate crystallinity, and the solvent resistance of the resin layer 21 becomes excellent. On the other hand, if the melting point of the resin constituting the resin layer 21 is 170° C. or lower, the crystallinity of the resin does not become too high, and the base film 1 can effectively exhibit excellent expandability.

In addition, in the dicing sheet 1 according to this embodiment, the difference between the melting point and the fluidization temperature of the resin constituting the resin layer 21 is 40°C or higher, preferably 50°C or higher, and more preferably 60°C or higher as described above. In addition, the difference between the melting point of the resin and the fluidization temperature is 190°C or less as described above, preferably 135°C or less, and more preferably 80°C or less. When the difference is 40°C or higher, a good effect of suppressing wire-like chips can be obtained. In addition, with the difference being 190°C or less, the resin exhibits an appropriate fluidization temperature, making it excellent in processing suitability. For example, when using such a resin to manufacture the base film 2, it becomes easier to melt pellet-shaped resin and shape it into a sheet shape. In addition, after radiation such as electron beams or gamma rays, the resin that forms a bridge structure through covalent bonding does not become fluidized.

In the dicing sheet 1 according to the present embodiment, the fluidization temperature of the resin constituting the resin layer 21 is preferably 100°C or higher, more preferably 120°C or higher, and particularly preferably 140°C or higher. In addition, the fluidization temperature of the resin is preferably 360°C or lower, more preferably 275°C or lower, and particularly preferably 200°C or lower. By setting the fluidization temperature of the resin to 100°C or higher, a good effect of suppressing the generation of the above-mentioned filamentous cutting chips can be obtained. In addition, by setting the fluidization temperature to 360°C or less, the processing suitability is improved. Excellent.

In the dicing sheet 1 according to the present embodiment, the tensile modulus of elasticity of the resin layer 21 at 23° C. is preferably 30 MPa or more, more preferably 40 MPa or more, and particularly preferably 50 MPa or more. In addition, the tensile modulus of elasticity is preferably 500 MPa or less, more preferably 300 MPa or less, and particularly preferably 200 MPa or less. By setting the above-mentioned tensile modulus of elasticity to 30 MPa or more, the dicing sheet 1 has appropriate strength and excellent adhesion fitness. Specifically, the dicing sheet 1 can be effectively prevented from being elongated when the dicing sheet 1 is attached to a wafer and a ring frame. In addition, by making the above-mentioned tensile elastic modulus less than 500 MPa, it is possible to avoid applying excessive stress to the dicing sheet 1 during the expansion process, and the dicing sheet 1 will not peel off from the ring frame during expansion and maintain a good condition. In addition, the above-mentioned tensile elastic modulus is a value measured based on JIS K7127: 1999, and the specific measurement method is carried out according to the test method described later.

In the dicing sheet 1 according to the present embodiment, the resin temperature of the resin layer 21 is 190°C and the melt flow rate with a load of 2.16 kg is preferably 0.5 g/10 min or more, more preferably 0.7 g/10 min or more, particularly preferably Above 1g/10min. In addition, the melt flow rate is preferably 10g/10min or less, more preferably 8g/10min or less, and particularly preferably 7g/10min or less. When the melt flow rate is within the above-mentioned range, when the base film 2 including the resin layer 21 is formed by extrusion, a uniform film thickness can be effectively achieved. In addition, the above-mentioned melt flow rate is a value measured with a temperature of 190°C and a load of 2.16 kg based on JIS K7210:2014.

When the base film 2 is formed of only the resin layer 21 as shown in FIG. 1, the thickness of the resin layer 21 is preferably 20 μm or more, more preferably 40 μm or more, and particularly preferably 60 μm or more. In addition, the thickness is preferably 600μm or less, more preferably 300μm Hereinafter, it is particularly preferably 200 μm or less. In addition, when the base film 2 is formed of a resin layer 21 and a second resin layer 22 as shown in FIG. 2, the individual thickness of the resin layer 21 is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 30 μm or more . In addition, the thickness is preferably 300 μm or less, more preferably 120 μm or less, and particularly preferably 100 μm or less. The thickness of the resin layer 21 is 20 μm or more when the base film 2 is formed of only the resin layer 21, and the thickness of the base film 2 is 10 μm or more when the base film 2 is formed of the resin layer 21 and the second resin layer 22. Inhibit the effect of wire cutting chips. In addition, since the thickness of the resin layer 21 is 600 μm or less when the base film 2 is formed of the resin layer 21 only, and the base film 2 is 300 μm or less when the base film 2 is formed of the resin layer 21 and the second resin layer 22, The cutting sheet 1 can effectively exert excellent expandability.

(1-2) Composition of resin layer, etc.

Regarding the resin constituting the resin layer 21, there is no particular limitation as long as the above-mentioned physical properties can be achieved.

Take, for example, the resin that constitutes the resin layer 21 that can achieve such physical properties. It is a resin that contains olefins as a constituent and has multiple molecular chains, which are formed by dynamic covalent bonding of temperature dependence. The resin is better. In the patent specification of the present invention, the so-called "temperature-dependent dynamic covalent bonding" refers to the situation where the covalent bonding of the linking reaction and the dissociation reaction is reversibly produced depending on the temperature (through heating and cooling). Since the molecular chains of this resin are covalently bonded with each other with temperature, the fluidization temperature is higher than that of resins whose molecular chains are not always linked. As a result, good results can be obtained as described above. The effect of inhibiting wire-like cutting chips. In addition, since the molecular chains are covalently bonded to each other with temperature, the base film 2 does not need to be irradiated to make it covalently bonded during production. Processes such as electron beams can suppress the increase in manufacturing costs.

As a component constituting the above-mentioned olefin, a plurality of molecular chains contained are taken as an example, and an ethylene-based copolymer containing ethylene and a base polymerizable acid anhydride as a structural unit can be cited as an example. Since the polarity of the ethylene-based copolymer is relatively low, the resin obtained from the ethylene-based copolymer has excellent solvent resistance.

As an example of the constituent ethylene-based copolymer, the polymerizable acid anhydride contained is used as an example, and examples include maleic anhydride, Iconan anhydride, citraconic anhydride, Endic anhydride, 1-butene-3,4-dimethyl anhydride, etc. . These may be used singly or in combination of two or more. Among them, maleic anhydride is preferably used from the viewpoint of reactivity and economy.

The content of the polymerizable acid anhydride in the ethylene copolymer is preferably 0.1% by mass or more, and more preferably 0.3% by mass or more in the unit constituting the ethylene copolymer. In addition, the content is preferably 20% by mass or less of the constituent units constituting the ethylene-based copolymer, and more preferably 5.0% by mass or less. By setting the content to 0.1% by mass or more, the resin constituting the resin layer 21 can sufficiently perform the aforementioned temperature-dependent dynamic covalent bonding, and a good effect of suppressing the production of the aforementioned filamentary cutting chips can be obtained. In addition, by making the content 20% by mass or less, the aforementioned temperature-dependent dynamic covalent bonding can be generated at an appropriate density. Accordingly, the elastic modulus of the resin layer 21 becomes appropriate, and the dicing sheet 1 can perform better Excellent scalability.

The said ethylene-type copolymer may contain the structural unit other than ethylene and a base polymerizable acid anhydride (Hereinafter, it may be called a "third monomer"). According to this, the melting point, fluidization temperature, flexibility, etc. of the resin layer 21 can be controlled more easily. Examples of constituent units other than ethylene and polymerizable acid anhydrides: ethylenically unsaturated ester compounds, ethylenically unsaturated amide compounds, ethylenically unsaturated carboxylic acid compounds, ethylene Unsaturated ether compounds, ethylenically unsaturated hydrocarbon compounds, etc.

More specific examples of the above-mentioned third monomer include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, (meth)acrylic acid Octyl ester, benzyl (meth)acrylate, methyl fumarate, ethyl fumarate, dimethyl maleate, diethyl maleate, vinyl acetate, (meth)acrylamide, N -Methyl (meth)acrylamide, N,N-dimethylacrylamide, (meth)acrylic acid, fumaric acid, methyl vinyl ether, methallyl ether, styrene, butadiene, Acrylonitrile etc. These may be used individually by 1 type, and may be used in combination of 2 or more types. In addition, "(meth)acrylic acid" in the patent specification of the present invention means both acrylic acid and methacrylic acid, and other similar terms are also the same.

In the case of using the above-mentioned third monomer, its content is preferably 30% by mass or less in the structural units constituting the ethylene-based copolymer, and more preferably 25% by mass or less. When the content is 30% by mass or less, an excessive drop in the melting point of the resin can be suppressed, and the practical heat resistance of the resin layer 21 can be exerted.

The aforementioned temperature-dependent dynamic covalent bonding can be taken as an example of an ester chain, especially as a molecular chain. In the case of using the aforementioned ethylene copolymer, the resin constituting the resin layer 21 further includes a polyvalent chain having two or more hydroxyl groups. The alcohol compound, as a temperature-dependent dynamic covalent bond, is preferably an ester linkage formed between the hydroxyl group of the polyvalent alcohol compound and the carboxyl group derived from the above-mentioned polymerizable acid anhydride. By generating such ester linkages, the above-mentioned ethylene-based copolymers bridge each other through the above-mentioned polyvalent alcohol compound. Accordingly, the ethylene-based copolymers are restricted to each other, and the fluidization temperature becomes higher than that of resins that do not always include a bridging structure, and as described above, a good effect of suppressing the generation of filamentous cutting chips can be obtained.

The above-mentioned polyvalent alcohol compounds can be exemplified: ethylene glycol, diethylene glycol, Triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, trimethylolethane, trimethylolpropane, neopentylerythritol, Arbitol, sorbitol Sugar alcohol, xylose, glucose, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyolefin oligomers containing two or more hydroxyl groups per molecule, ethylene-hydroxyethyl (meth)acrylic acid copolymer Such as polymers having a plurality of hydroxyl groups in the molecule, polyoxyalkylene compounds obtained by adding ethylene oxide or propylene oxide to the same alcohol compound as described above, polyglycerol esters, and the like. These may be used individually by 1 type, and may be used in combination of 2 or more types. In addition, in terms of the melting point of these polyvalent alcohol compounds, from the viewpoint of easy mixing with other compounds when suppressing the ethylene-based copolymer, 300°C or less is preferred.

The amount of the polyvalent alcohol compound used is preferably 0.01 or more, and more preferably 0.05 or more of the hydroxyl molar ratio derived from the polyol relative to the carboxyl group derived from the above-mentioned polymerizable acid anhydride. In addition, the molar ratio is preferably 10 or less, and more preferably 5 or less.

The covalent bond produced by the Diels-Alder reaction is also an example of the aforementioned temperature-dependent dynamic covalent bond. In this reaction, the conjugated diene structure and the Dienophile structure produce a 6-membered ring structure, and 6 The dissociation reaction of the conjugated diene structure and the Dienophile structure in the ring structure occurs with temperature. In the case of using such temperature-dependent dynamic covalent bonding, for example, a molecular chain having a conjugated diene structure in the side chain and a compound having multiple Dienophile structures are used in combination. In this case, the molecular chain has multiple Dienophile structured compounds are bridged.

A molecular chain with a conjugated diene structure on the side chain can be a molecular chain with a furan ring on the side chain as an example. This molecular chain has an amine group and can connect the conjugated diene compound through the amine group. Obtained from branches. Conjugated diene As for the compound, for example: furan methylamine, 5-methyl furan methylamine, N-methyl-furan methylamine, pyrrole, 1-aminopyrrole, imidazole, 1-(3-aminopropyl ester) imidazole, 2-(2-aminoethyl)thiophene, pyrazole, 3-aminopyrazole, 3-amino-5-methylisoxazole, triazole, 3-amino-1,2,4 triazole , 4-Amino-1,2,4 triazole, etc.

Compounds with multiple Dienophile structures can be exemplified: bis(3-ethyl-5-methyl-4 maleimidimidphenyl)methane, 4,4'-bismaleimidodiphenyl Methyl methane, 1,2-bis(maleimide)ethane, 1,6-bis(maleimide)hexane, N,N'-1,3-phenylene bis Maleic amide, N,N'-1,4-phenylene bis maleic amide, etc.

In the resin constituting the resin layer 21, when the molecular chains are linked to each other through temperature-dependent dynamic covalent bonding, the resin further includes a reaction that promotes the temperature-dependent dynamic covalent bonding and dissociation reaction. The accelerator is better. The reaction accelerator accelerates the linking speed and the dissociation speed of the temperature-dependent dynamic covalent bonding, so that the reversible phase transition proceeds rapidly. Therefore, the resin is heated. Melt film formation becomes easier, and as a result, it is possible to simultaneously achieve the aforementioned effect of suppressing filamentary cutting chips and excellent film forming properties.

Examples of the aforementioned reaction accelerator include metal salts of carboxylic acids or metal salts of polymers containing carboxyl groups. Metal salts of carboxylic acids include acetic acid, butyric acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, succinic acid, benzoic acid, terephthalic acid, Metal salts of carboxylic acids such as pyromellitic acid and elements of group IA, IIA, IIB, and IIIB of the periodic table (for example, Li, Na, K, Mg, Ca, Zn, Al, etc.).

Examples of metal salts of polymers containing carboxyl groups: part or all of the carboxyl groups of the ethylene-(meth)acrylic acid copolymer and group IA and IIA of the periodic table Group, IIB, IIIB elements (for example: Li, Na, K, Mg, Ca, Zn, Al, etc.) metal salts, or copolymers of ethylene and ethylene-(meth)acrylic acid metal salts, etc. Moreover, as a monomer of the polymer containing a carboxyl group, the said 3rd monomer can also be used.

In addition, the above-mentioned reaction accelerator may also be graft-polymerized unsaturated carboxylic acid metal salt to polyolefin resins such as polyethylene and polypropylene. In addition, the above-mentioned reaction promoters can be exemplified: triethylamine, trimethylamine, tetramethylammonium tetrafluoroborate, tetramethylammonium hexafluorophosphoric acid, tetramethylammonium bromide, tetraethylammonium bromide, and the like.

These reaction accelerators may be used individually by 1 type, and may be used in combination of 2 or more types. In addition, among these reaction accelerators, it is preferable to use a metal carboxylate from the viewpoint of ease of handling and economy.

Although the amount of the reaction accelerator used can be appropriately adjusted according to its kind, in general, it is preferably 0.001 parts by mass or more, and more preferably 0.01 parts by mass or more with respect to 100 parts by mass of the ethylene copolymer before side chain introduction. In addition, the usage amount is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less.

In the dicing sheet 1 according to the present embodiment, as the resin constituting the resin layer 21, commercially available products may also be used, such as the thermoplastic resin Rexpearl series manufactured by Japan Polyethylene Corporation, and Rexpearl ES323Y or Rexpearl ES333Y is preferably used. Since these commercially available products are resins containing the aforementioned ethylene copolymer, the aforementioned polyvalent alcohol compound and the reaction accelerator, the ethylene copolymer can be bridged by the polyvalent alcohol compound to achieve the aforementioned melting point. Physical properties related to fluidization temperature.

In the resin layer 21, in addition to the above-mentioned resins that achieve the above-mentioned physical properties related to the melting point and fluidization temperature, pigments, dyes, flame retardants, Various additives such as plasticizers, antistatic agents, lubricants, and fillers. As for the pigment, titanium dioxide, carbon black, etc. can be exemplified. In addition, as for the filler, organic materials such as melamine resin, inorganic materials such as fumed silica, and metallic materials such as nickel particles can be cited.

In order to improve the adhesion between the adhesive layer 3 side surface of the resin layer 21 and the adhesive layer 3, surface treatments such as primer treatment, corona treatment, and plasma treatment may also be performed. In addition, when the base film is formed only with the resin layer 21, various coating films may be formed on the opposite surface of the adhesive layer 3 of the resin layer 21.

(1-3) The second resin layer

In the case where the base film 2 includes the second resin layer 22 as shown in FIG. 2, the material constituting the second resin layer 22 is not particularly limited. A resin film generally used for the base material of a dicing sheet can be used. This resin film Specific examples include: ethylene-vinyl acetate copolymer film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylate copolymer film and other ethylene copolymer films; polyethylene film, polypropylene film, Polyolefin films such as polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, norbornene resin film; polyvinyl chloride film, vinyl chloride copolymer film, etc. Vinyl chloride film; polyester film such as polyethylene terephthalate film and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; fluororesin Film etc. Examples of polyethylene films include low-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, and high-density polyethylene (HDPE) films. In addition, denatured films such as bridge films and ionomer films can also be used. The substrate may be a film formed of one of these, or a laminated film of a combination of two or more of these.

Among the above resin films, from the interlayer adhesion, molding processability, From the point of view of expandability and solvent resistance, ethylene-based copolymer films are used, especially ethylene-vinyl acetate copolymer films, ethylene-(meth)acrylic acid copolymer films and ethylene-(meth)acrylate copolymers Films; polyolefin films, especially polyethylene films, polypropylene films, polybutene films, ethylene-norbornene copolymer films and norbornene resin films; polyurethane films; polystyrene films or fluororesin films are preferred .

The second resin layer 22, like the resin layer 21, may contain various additives such as pigments, dyes, flame retardants, plasticizers, antistatic agents, lubricants, and fillers in addition to the aforementioned resins. In addition, various coating films may be formed on the opposite surface of the adhesive layer in the second resin layer 22.

Although the thickness of the second resin layer 22 is not particularly limited, it is preferably 10 μm or more, more preferably 40 μm or more, and particularly preferably 50 μm or more. In addition, the thickness is preferably 300 μm or less, more preferably 120 μm or less, and particularly preferably 100 μm or less. Since the thickness of the second resin layer 22 is 10 μm or more, the dicing sheet 1 has appropriate strength, and the adhesion suitability is improved. When the thickness of the second resin layer 22 is 300 μm or less, the dicing sheet 1 can effectively exhibit excellent expandability.

(1-4) Physical properties of the substrate film, etc.

In the dicing sheet 1 according to this embodiment, the thickness of the base film 2 is not particularly limited, and may be the same as the thickness of the base film of a general dicing sheet. For example, as shown in FIG. 1, when the base film 2 is formed of only the resin layer 21, the thickness is preferably 20 μm or more, more preferably 40 μm or more, and particularly preferably 60 μm or more. In addition, the thickness is preferably 600 μm or less, more preferably 300 μm or less, and particularly preferably 200 μm or less. In addition, as shown in FIG. 2, when the base film 2 is formed of a resin layer 21 and a second resin layer 22, the base film 2 includes two layers of the resin layer 21 and the second resin layer 22. The thickness is preferably 20 μm or more, more preferably 60 μm or more, particularly preferably 80 μm or more. In addition, the thickness is preferably 600 μm or less, more preferably 240 μm or less, and particularly preferably 200 μm or less.

The adhesive layer 3 contains an active energy ray curable adhesive. As the energy ray irradiated to harden the adhesive layer 3, when ultraviolet rays are used, the base film 2 is preferably transparent to ultraviolet rays. . In addition, when an electron beam is used as the energy beam, the base film 2 preferably has electron beam penetration.

(2) Manufacturing method of base film

The base film 2 can be manufactured by a general method. For example, after the resin constituting the resin layer 21 is obtained, the resin layer 21 is formed by forming the resin into a thin film by a melt extrusion molding method, a calendaring method, etc. 21 formed base film 2.

An ideal method for obtaining such a resin can be exemplified: copolymerizing a constituent unit containing at least ethylene and a base polymerizable acid anhydride to obtain an ethylene copolymer, and polymerizing the base of the ethylene copolymer in the presence of the aforementioned reaction accelerator The carboxyl group derived from the acid anhydride and the hydroxyl group of the aforementioned polyvalent alcohol compound are ester-linked. According to this, ethylene-based copolymers can obtain resins having a bridge structure in the above-mentioned polyvalent alcohol compound.

When a commercially available product is used as the resin constituting the resin layer 21, the commercially available product is molded into a film by a melt extrusion method, a calender method, or the like to form the resin layer 21.

When the base film 2 includes the second resin layer 22, the resin layer 21 and the second resin layer 22 can be laminated by a general co-extrusion method or a lamination method. Into the base film 2.

(3) Adhesive layer

There are no particular restrictions on the adhesive constituting the adhesive layer 3. As the dicing sheet 1, the usual adhesives such as rubber, acrylic, silicone, polyvinyl ether, etc. can be used The adhesive may also be an energy ray hardening type (including ultraviolet hardening type) or a heat hardening type adhesive. In addition, the cutting sheet 1 of this embodiment is used as a cutting. In the case of die bonding, use adhesives, thermoplastic adhesives, Bstage adhesives, etc. that have both the wafer fixing function and the die bonding function.

The thickness of the adhesive layer 3 is not particularly limited. For example, 3 μm or more is preferable, and 5 μm or more is more preferable. In addition, the thickness is preferably 100 μm or less, more preferably 80 μm or less.

(4) Peeling sheet

The dicing sheet 1 according to this embodiment may have a release sheet on the opposite side of the base film 2 of the adhesive layer 3, and the release sheet is used to protect the adhesive surface of the adhesive layer 3.

Examples of release sheets include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate Film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-( Meth) acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. In addition, these bridging films can also be used. In addition, a multilayer film formed by laminating a plurality of these films may also be used.

The peeling surface (the surface contacting the adhesive layer 3) of the above-mentioned peeling sheet is preferably subjected to a peeling treatment. Examples of the release agent used in the release treatment include alkyd resin, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents.

The thickness of the release sheet is not particularly limited. For example, 20 μm or more and 150 μm or less are preferable.

2. The manufacturing method of the cutting sheet

The manufacturing method of the dicing sheet 1 can also manufacture by a general method other than manufacturing the base film 2 by the above-mentioned method.

For example, first prepare a coating agent containing the adhesive composition for forming the adhesive layer 3 and an additional solvent added as needed, and then apply the coating agent on the release surface of the release sheet manufactured as described above , The adhesive layer 3 is formed by coating and drying with a die coater, curtain coater, sprayer, slit coater, knife coater, etc. After that, the opposite surface of the release sheet of the adhesive layer 3 and one surface of the base film 2 are bonded to obtain the dicing sheet 1. When the base film 2 includes the second resin layer 22, the surface on the resin layer 21 side of the base film 2 and the adhesive layer 3 are bonded. As long as the coating agent can be applied, its properties are not particularly limited, and the components used to form the adhesive layer 3 may be contained in a solute or a dispersion.

In another manufacturing method of the dicing sheet 1, the above-mentioned coating agent is applied on one side of the base film 2 (if the second resin layer 22 is present, the surface on the resin layer 21 side of the base film 2) After drying, the cutting sheet 1 formed by the adhesive layer 3 can be obtained on the substrate film 2.

In the dicing sheet 1 manufactured by the above-mentioned method, the resin constituting the resin layer 21 is formed by linking with each other through dynamic covalent bonding through temperature dependence Because of the structure of the daughter chain, the molecular chain is appropriately restricted, and the fluidization temperature is higher than that of resins that are not restricted by this type of restriction. As a result, it is possible to simultaneously achieve the above-mentioned wire-like cutting chip generation suppression effect and good expandability. In addition, since the molecular chains are covalently bonded to each other with temperature, there is no need to perform processes such as electron beam irradiation to make them covalently bonded, thereby suppressing the increase in manufacturing costs.

The above-described embodiments are described to facilitate the understanding of the present invention, and should not limit the scope of the present invention. Therefore, they belong to all design changes or equivalents within the technical scope of each element described in the above-mentioned embodiments. All should still fall within the scope of the invention patent.

For example, there may be other layers between the base film 2 and the adhesive layer 3 of the dicing sheet 1 described above.

(Example)

Hereinafter, the present invention will be further described in detail through examples, but the scope of the present invention is not limited by these examples.

[Example 1]

1. Production of base film

Thermoplasticity of an ethylene copolymer containing ethylene and a base polymerizable acid anhydride as a constituent unit, a polyvalent alcohol compound having two or more hydroxyl groups, and a reaction accelerator that promotes a temperature-dependent dynamic covalent bonding reaction and dissociation reaction The resin, the carboxyl group derived from the polymerizable acid anhydride of the vinyl copolymer and the hydroxyl group of the polyvalent alcohol compound are ester-chained in the presence of the reaction accelerator to form a thermoplastic resin (manufactured by Japan Polyethylene Corporation, product name "Rexpearl ES323Y ", temperature 190℃ and load 2.16kg melt flow rate: 4g/10min) with a small T-die extruder (TOYO Seiki Seisaku-Sho., Ltd. (Product name "Labo Plasto Mill") was extruded to obtain a base film formed of a resin layer with a thickness of 80 μm.

2. Preparation of adhesive composition

100 parts by mass of copolymer (Mw: 500,000) formed by copolymerizing 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid, and 120 parts by mass of acrylic urethane oligomer (Mw: 8,000), and isocyanic acid 5 parts by mass of salt-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L"), and photopolymerization initiator (manufactured by Chiba Speciality Chemicals Co., Ltd., product name "IRUGACURE 184") After mixing 4 parts by mass, an energy ray hardening adhesive composition is obtained.

3. The production of cutting pieces

Apply the energy ray-curable adhesive composition obtained in the above process 2 to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET38111(S)") that has been peeled off with a silicone-based release agent , Placed in 100 ℃ for 1 minute to dry to form an adhesive layer with a thickness of 10μm. The opposite side of the release sheet of the adhesive layer and the single side of the base film obtained in the above-mentioned process 1 are bonded to obtain a dicing sheet.

[Example 2]

Thermoplasticity of an ethylene copolymer containing ethylene and a base polymerizable acid anhydride as a constituent unit, a polyvalent alcohol compound having two or more hydroxyl groups, and a reaction accelerator that promotes a temperature-dependent dynamic covalent bonding reaction and dissociation reaction The resin, except for the use of the carboxyl group derived from the polymerizable acid anhydride of the vinyl copolymer and the hydroxyl group of the polyvalent alcohol compound in the presence of the reaction accelerator to form a thermoplastic resin (Japan Polyethylene Corporation Manufacture, product name "Rexpearl ES333Y", temperature of 190°C and load of 2.16kg melt flow rate: 6g/10min), the rest are the same as in Example 1 to obtain cut pieces.

[Comparative Example 1]

As the thermoplastic resin, a polyethylene resin with a density of 924 kg/m ³ (manufactured by Sumitomo Chemical Co., Ltd., product name "SUMIKASEN L405", temperature 190°C and melt flow rate with a load of 2.16 kg: 3.7 g/10 min) is used. Other than that, the rest are the same as in Example 1 to obtain the cut sheet.

[Comparative Example 2]

As the thermoplastic resin, in addition to using a random copolymer of propylene (manufactured by Prime Polymer Co., Ltd., product name "PRIME POLYPRO F-744NP", temperature 190°C and melt flow rate with a load of 2.16 kg: 7 g/10 min), The rest are the same as in Example 1 to obtain a cut sheet.

[Comparative Example 3]

As the thermoplastic resin, except for using high-density polyethylene (manufactured by Japan Polypropylene Corporation, product name "Novatec HY540", temperature 190°C and load 2.16kg melt flow rate: 1g/10min), the rest are the same as in Example 1. Obtain cut pieces.

[Comparative Example 4]

As the thermoplastic resin, in addition to using ethylene homopolymer high-pressure low-density polyethylene (manufactured by Sumitomo Chemical Co., Ltd., product name "SUMIKASEN F101-1", temperature 190°C and load 2.16kg melt flow rate: 0.3g /10 min), the rest are the same as in Example 1 to obtain cut pieces.

[Comparative Example 5]

As the thermoplastic resin, except for using low-density polyethylene (manufactured by Sumitomo Chemical Co., Ltd., product name "SUMIKASEN G801", temperature 190°C and melt flow rate with a load of 2.16 kg: 20 g/10 min), the rest are the same. Example 1 is the same to obtain cut pieces.

[Comparative Example 6]

As the thermoplastic resin, except for the use of polypropylene elastomer (manufactured by Mitsui Chemicals, Inc., product name "TIMER PN2070", temperature 190°C and melt flow rate with a load of 2.16 kg: 3.2 g/10 min), everything else is implemented Example 1 is the same to obtain cut pieces.

[Comparative Example 7]

As the thermoplastic resin, except for the use of ethylene-α-olefin (manufactured by Mitsui Chemicals, Inc., product name "TIMER 4070S", temperature 190°C and melt flow rate of 2.16 kg load: 3.6 g/10 min), the rest are the same. Example 1 is the same to obtain cut pieces.

[Comparative Example 8]

As the thermoplastic resin, except for the use of poly-4-methyl-1-pentene (manufactured by Mitsui Chemicals, Inc., product name "TPX MX002", temperature 190°C and melt flow rate with a load of 2.16 kg: 0 g/10 min), The rest are the same as in Example 1 to obtain a cut sheet.

[Test example 1] (Measurement of tensile elastic modulus)

The base films obtained in the Examples and Comparative Examples were cut into 15 mm×140 mm test pieces, and the tensile modulus of elasticity was measured based on JIS K7127:1999. Specifically, the above-mentioned test piece was placed in a tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-IS 500N"), and the distance between the chuck The distance was set to 100 mm, and a tension test was performed at a speed of 200 mm/min to measure the tensile modulus (MPa). The results are shown in Table 1. However, when the base film cannot be formed well and the tensile elastic modulus cannot be measured, it is indicated in Table 1 with "-".

[Test Example 2] (Melting Point Measurement)

The melting point of the thermoplastic resin used in the examples and comparative examples is measured with a differential scanning calorimeter (manufactured by DSC T.A. INSTRUMENTS, product name "Q2000") based on JIS K7121.

[Test Example 3] (Measurement of fluidization temperature)

The fluidization temperature of the thermoplastic resin used in the examples and comparative examples was measured with a descending flow tester (manufactured by Shimadzu Corporation, model "CFT-100D"), with a load of 5.0N, a hole shape of φ2.0mm, and a length of 5.0 mm die, increase the temperature rise rate of measuring sample temperature to 10℃/min, and measure the variable stroke displacement speed (mm/min) at the same time to obtain the temperature dependence of the stroke displacement speed of the sample chart. In this temperature dependency graph, after the peak value obtained by exceeding the softening point, the temperature at which the stroke displacement speed starts to rise again is used as the fluidization temperature. The results are shown in Table 1.

In addition, after subtracting the melting point value obtained in Test Example 2 from the obtained fluidization temperature value, the same temperature difference ΔT (°C) was calculated. The results are shown in Table 1.

[Test Example 4] (Evaluation of Film Formability)

(1) Production of two kinds of two-layer substrate films

The resins and low-density polyethylene used in the examples and comparative examples (manufactured by Sumitomo Chemical Co., Ltd., product name "SUMIKASEN L705", temperature 190°C and melt flow rate with a load of 2.16 kg: 7.0 g/10 min ) Use a feed block to make the ratio of these resins 5:5, using a small T mold An extruding machine (manufactured by TOYO Seiki Seisaku-Sho., Ltd., product name "Labo Plasto Mill") was extruded to obtain a base film formed of two types of two resin layers with a thickness of 80 μm.

(2) Evaluation

Regarding the single-layer base film produced in the examples and the comparative examples and the two types of two-layer base film produced in the above (1), the film-forming properties of the examples and the comparative examples were evaluated. Specifically, for single-layer and two-layer two-layer films, samples for evaluation can be produced well. Those who rated it as ○, the thickness accuracy is unstable, die lines appear, or the base film is stuck on Cooling the drum to make the sample preparation on one or both sides of the film impossible was evaluated as ×. The results are shown in Table 1.

[Test Example 5] (Evaluation of cutting chips)

For the dicing sheets of the Examples and Comparative Examples whose film forming properties were evaluated as ○ in Test Example 4, the adhesive layer was attached to the polysilicon wafer, and then placed on a dicing device (manufactured by DISCO, product name "DFD- 651”) Cut according to the following conditions.

. Work product (adhesive body): polysilicon wafer

. Work product size: 6 inches, thickness 0.35mm

. Cutting knife: made by DISCO, product name "27HEEE"

. Blade rotation number: 50,000rpm

. Cutting speed: 10mm/sec

. Cutting depth: cutting depth of 25μm from the surface of the base film

. Cutting size: 5mm×5mm

Then, ultraviolet rays (light intensity: 160 mJ/cm ² ) are irradiated to the base film side, and the cut wafer is peeled from the dicing sheet. In the longitudinal and transverse cutting lines, the number of filamentary cutting chips produced on the longitudinal and transverse 1 lines near the center of each is used with a digital microscope (manufactured by Keyence Corporation, product name "VHX-100", magnification : 100 times) Count, the number of filamentous shavings is 0 to 10, it is evaluated as ○, and 11 or more is evaluated as x. The results are shown in Table 1.

[Test Example 6] (Evaluation of Adhesion Suitability)

For the dicing sheets of the Examples and Comparative Examples whose film forming properties were evaluated as ○ in Test Example 4, a 6-inch wafer was pasted on the adhesive layer, and the dicing sheet was placed on a flat frame, and then When the flat frame was lifted up parallel to the ground, if the cut piece did not soften, it was evaluated as ○, and if softening occurred, it was evaluated as x. The results are shown in Table 1.

[Test Example 7] (Evaluation of scalability)

For the dicing sheets of the examples and comparative examples whose adhesion suitability was evaluated as ○ in the above-mentioned test example 6, the same device as that used in the test example 4 was used to cut under the same conditions.

Then irradiate the side of the base film with ultraviolet light (light quantity: 160mJ/cm ² ), and then use an expansion jig (manufactured by NEC Machinery, product name "Die-Bonder CSP-1000VX"), and set the cutting disc at a speed of 2mm/sec. Pull down 20mm, if the dicing piece is not torn or the dicing piece does not peel off from the flat frame to achieve expansion, it is evaluated as ○, if the dicing piece is torn or the dicing piece peels off from the flat frame, it is evaluated as ×. The results are shown in Table 1. .

[Test Example 8] (Evaluation of solvent resistance)

For the examples and comparative examples in which the film forming property is evaluated as ○ in the above test example 4, butyl acetate is dropped on the substrate films obtained in these examples and comparative examples and placed at room temperature for 10 minutes. If there is no change, it is evaluated as ○, and if swelling occurs, it is evaluated as ×. The results are shown in Table 1.

It can be seen from Table 1 that the cutting blades manufactured in the examples are difficult to produce filamentary cutting blades, and exhibit excellent expandability. In addition, the dicing sheets manufactured in the examples are excellent in film forming properties, adhesion suitability, and solvent resistance.

(Industrial availability)

The dicing sheet related to the present invention is suitable for dicing semiconductor wafers or various packages.

Claims (8)

A dicing sheet having a substrate film and an adhesive layer laminated on one side of the substrate film, characterized in that the substrate film has at least a resin layer located at the portion closest to the adhesive layer, and is composed The resin melting point of the resin layer is 60°C or higher and 170°C or lower, and the difference between the resin melting point and the fluidization temperature is 40°C or higher and 190°C or lower. The dicing sheet according to claim 1, wherein the resin includes a plurality of molecular chains containing olefins as constituents, and the molecular chains are linked by dynamic covalent bonding through temperature dependence. The dicing sheet according to the second item of the scope of patent application, wherein the above-mentioned molecular chain system contains as a constituent unit an ethylene-based copolymer of ethylene and a base polymerizable acid anhydride, and the above-mentioned resin has a polyvalent alcohol compound having two or more hydroxyl groups The temperature-dependent dynamic covalent bond is an ester linkage between the carboxyl group derived from the polymerizable acid anhydride and the hydroxyl group of the polyvalent alcohol compound. According to the dicing sheet described in item 2 or 3 of the scope of patent application, the resin further contains a reaction promoter that promotes the temperature-dependent dynamic covalent bonding of the linkage reaction and the dissociation reaction. The dicing sheet according to any one of items 1 to 3 in the scope of patent application, wherein the tensile modulus of elasticity of the resin layer at 23° C. is 30 MPa or more and 500 MPa or less. According to the cutting blade described in any one of items 1 to 3 in the scope of patent application, which Among them, the melt flow rate of the above resin at a temperature of 190°C and a load of 2.16kg is 0.5g/10min or more and 10g/10min or less. The dicing sheet according to any one of items 1 to 3 in the scope of patent application, wherein the base film further has a second resin layer on the opposite side of the adhesive layer of the resin layer. A method for manufacturing a dicing sheet is the method for manufacturing a dicing sheet according to any one of items 1 to 3 in the scope of the patent application, characterized by comprising: copolymerizing constituent units containing at least ethylene and a base polymerizable acid anhydride to obtain The production process of vinyl copolymers; and the carboxyl groups and molecules derived from the polymerizable acid anhydrides of the vinyl copolymers in the presence of reaction accelerators that promote temperature-dependent dynamic covalent bonding and dissociation reactions The process of obtaining the above-mentioned resin by making ester chains between the hydroxyl groups of the polyvalent alcohol compound having more than two hydroxyl groups.

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