JP2024008947A - Base film for dicing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base film for dicing that has high heat recovery properties and excellent rack recovery properties, and provide a base film for dicing that allows a dicing film to stretch uniformly even when expanding under a low temperature condition.

SOLUTION: A base film for dicing includes a structure in which a surface layer, a middle layer and a back layer are laminated in this order, the surface layer and the back layer are made of a resin composition containing polyethylene resin, and the middle layer is made of a resin composition containing a polyurethane resin.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a dicing base film that is used by being attached and fixed to a semiconductor wafer when dicing the semiconductor wafer into chips.

As a method for manufacturing semiconductor chips, there is a method in which a large area semiconductor wafer is manufactured in advance, the semiconductor wafer is then diced (cut and separated) into chips, and finally the diced chips are picked up. In recent years, stealth dicing has become known as a method for cutting semiconductor wafers, in which a laser processing device is used to cut (divide) a semiconductor wafer without contacting the semiconductor wafer.

As a method to improve the cutting performance (dividing performance) of semiconductor wafers by stealth dicing, expansion is performed under low temperature conditions of -15 to 5°C to suppress the elongation of the die bond film provided on the dicing tape. A wafer processing tape is known in which a semiconductor wafer and a die-bonding film are effectively cut (separated) at once by a method of increasing stress (Patent Documents 1 and 2).

Japanese Patent Application Publication No. 2015-185584 Japanese Patent Application Publication No. 2015-185591

An object of the present invention is to provide a base film for dicing that has high thermal recovery properties and excellent rack recovery properties.

A further object of the present invention is to provide a base film for dicing that stretches uniformly even when expanded under low temperature conditions.

The present invention further provides that when the semiconductor wafer and the die bond layer are cut (divided) after stealth dicing (laser dicing), even when expanding is performed under low temperature conditions (-15 to 5 degrees Celsius) and high speed conditions, An object of the present invention is to provide a base film for dicing that stretches.

In semiconductor manufacturing lines, it is desired to temporarily store sheets (dicing films including dicing base films) in which products are still being processed after the expanding process in racks. At that time, if any slack remains in the sheet, it tends to lead to problems such as the products not being able to be stored properly in a rack or products colliding with each other, resulting in defects. The rack is a name used in the industry, and is also called a zipper, a case, etc.

In order to solve this problem, it is necessary to eliminate the slack in the sheet after the expanding process. As a method for this, there is a heat shrink technology (heat shrink restoration technology). This is to heat the sagging part caused by the expansion process to shrink that part and eliminate the sagging (high recovery rate due to heat shrinkage).

For example, even when expanding is performed under low-temperature conditions of -15 to 5°C, it is required that the dicing film be expanded uniformly and that the semiconductor wafer be cut well.

Furthermore, for example, even when expanding is performed under high speed conditions in addition to the low temperature conditions after stealth dicing, the dicing film can be stretched well and the semiconductor wafer and the die bond layer can be cut (separated) well. is required.

The present inventor conducted extensive research to solve the above problems.

The base film for dicing includes a structure in which the following layers are laminated in the order of surface layer/intermediate layer/back layer, and by using a polyurethane resin for the intermediate layer, the sheet after the expanding process (dicing film including the base film for dicing) It has been found that the sagging can be effectively eliminated by heat shrink technology (heat shrink restoration technology).

It has been found that the dicing film can be uniformly expanded even when the dicing base film is expanded under low temperature conditions. It has been found that the dicing film can be expanded well even when the base film for dicing is expanded under high-speed conditions in addition to low-temperature conditions.

Item 1.
A base film for dicing including a structure in which a surface layer/intermediate layer/back layer are laminated in this order,
The surface layer and the back layer are made of a resin composition containing polyethylene resin,
The intermediate layer is made of a resin composition containing a polyurethane resin.
Base film for dicing.

Item 2.
2. The substrate film for dicing according to item 1, wherein the surface layer and/or the back layer is a single layer or a multilayer.

Item 3.
The polyethylene resin may be branched low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene- At least one resin selected from the group consisting of ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer (EMMA), ethylene-methacrylic acid copolymer (EMAA), and ionomer resin The base film for dicing according to item 1 or 2 above.

Item 4.
4. The base film for dicing according to any one of items 1 to 3, wherein the polyurethane resin is a thermoplastic polyurethane resin (TPU).

Item 5.
A dicing film comprising an adhesive layer and a die-bonding layer provided in this order on the surface layer side of the dicing base film according to any one of items 1 to 4 above.

Item 6.
A dicing base film used for manufacturing a stealth dicing film,
The stealth dicing film is used when expanding at a low temperature of -15 to 5°C,
The base film for dicing includes a structure in which a surface layer/intermediate layer/back layer are laminated in this order,
The surface layer and the back layer are made of a resin composition containing a polyethylene resin,
The intermediate layer is made of a resin composition containing thermoplastic polyurethane resin (TPU),
In the stealth dicing film, an adhesive layer and a die bonding layer are provided in this order on the surface side of the dicing base film,
The intermediate layer is made of a resin composition containing 0 to 50% by weight of a polyethylene resin and the remaining amount of a thermoplastic polyurethane resin (TPU).
Base film for dicing.

By using the dicing base film of the present invention, used dicing films can be collected more quickly and easily into a rack. In other words, the dicing substrate film of the present invention has high heat recovery properties, that is, exhibits good heat shrink properties and is excellent in rack recovery properties.

When the base film for dicing of the present invention is used, the dicing film is uniformly expanded even when expanding is performed under low temperature conditions.

When the base film for dicing of the present invention is used, for example, when cutting (dividing) a semiconductor wafer and a die bond layer after stealth dicing, the dicing film can be Stretch well.

The present invention relates to a base film for dicing.

Furthermore, the present invention relates to a dicing film in which an adhesive layer and a die-bonding layer are provided in this order on a base film for dicing.

(1) Base film for dicing The base film for dicing of the present invention is:
It is characterized by including a structure in which a surface layer/intermediate layer/back layer are laminated in this order.

It is preferable that the surface layer and/or the back layer are a single layer or a multilayer.

Hereinafter, each layer constituting the base film for dicing of the present invention will be explained in detail.

(1-1) Surface layer The surface layer is made of a resin composition containing a polyethylene resin.

The polyethylene resins contained in the surface layer include branched low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene-vinyl acetate copolymer (EVA), and ethylene-methyl acrylate copolymer (EMA). , ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer (EMMA), ethylene-methacrylic acid copolymer (EMAA), and at least one ionomer resin. Preferably, seed components are used.

Since the surface layer is made of a resin composition containing at least one of these components, the expandability of the base film for dicing, that is, the tensile properties of the base material are excellent.

In addition, a polypropylene resin may be blended as long as the effects of the present invention are not impaired.

The melt flow rate (MFR) of ethylene-vinyl acetate copolymer (EVA) at 190°C should be about 30 g/10 minutes or less, preferably about 20 g/10 minutes or less, and more preferably about 15 g/10 minutes or less. Preferably, about 10 g/10 minutes or less is more preferable. By setting the above MFR to 10 g/10 minutes or less, the viscosity difference with the intermediate layer can be suppressed, so stable film formation is possible.

Furthermore, the MFR of EVA is preferably about 0.1 g/10 minutes or more, more preferably about 0.3 g/10 minutes or more, in order to facilitate extrusion of the resin.

The density of EVA is preferably about 0.9 to 0.96 g/cm ³ , more preferably about 0.92 to 0.94 g/cm ³ .

The melt flow rate (MFR) of branched low density polyethylene (LDPE) at 190°C is preferably about 10 g/10 minutes or less, more preferably about 6 g/10 minutes or less. By setting the above MFR to 10 g/10 minutes or less, the viscosity difference with the intermediate layer can be suppressed, so stable film formation is possible.

Further, the MFR of LDPE is preferably about 0.1 g/10 minutes or more, more preferably about 0.3 g/10 minutes or more, in order to facilitate extrusion of the resin.

The density of LDPE is preferably about 0.9 to 0.94 g/cm ³ , more preferably about 0.91 to 0.93 g/cm ³ .

The melt flow rate (MFR) of linear low density polyethylene (LLDPE) at 190°C is preferably about 10 g/10 minutes or less, more preferably about 6 g/10 minutes or less. By setting the above MFR to 10 g/10 minutes or less, the viscosity difference with the intermediate layer can be suppressed, so stable film formation is possible.

Further, the MFR of LLDPE is preferably about 0.1 g/10 minutes or more, more preferably about 0.3 g/10 minutes or more, in order to facilitate extrusion of the resin.

The density of LLDPE is preferably about 0.9 to 0.94 g/cm ³ , more preferably about 0.91 to 0.93 g/cm ³ .

Here, the melt flow rate (MFR) was determined in accordance with ISO 1133, and the density was determined in accordance with ISO 1183-1:2004.

The surface layer may further contain an antistatic agent, if necessary. The antistatic agents that can be used in the surface layer can also be used in the surface layer. As the antistatic agent used in the surface layer, known surfactants such as anionic, cationic, and nonionic surfactants can be selected, but from the viewpoint of sustainability and durability, nonionic surfactants such as PEEA resin and hydrophilic PO resin surfactants are preferred.

When the surface layer contains an antistatic agent, the content of the antistatic agent in the resin composition of the surface layer is preferably about 5 to 25% by weight, more preferably about 7 to 22% by weight. By blending the antistatic agent within the above range, the slipperiness of the surface layer when uniformly expanded in contact with the expand ring is not impaired.

Furthermore, since semiconductivity is effectively imparted, it becomes possible to quickly eliminate static electricity that occurs. For example, the substrate film for dicing of the present invention containing an antistatic agent in the above-mentioned range is preferable because the surface resistivity of the back surface thereof is about 10 ⁷ to 10 ¹² Ω/□.

An anti-blocking agent or the like may be further added to the surface layer. Adding an anti-blocking agent is preferable because it suppresses blocking when the base film for dicing is wound into a roll. Examples of the anti-blocking agent include inorganic or organic fine particles.

(1-2) Back layer Like the surface layer, the back layer is made of a resin composition containing a polyethylene resin.

The polyethylene resin used for the surface layer may be used, or a polyethylene resin different from that for the surface layer may be used.

Further, if necessary, it may contain an antistatic agent or an anti-blocking agent like the surface layer.

In the substrate film for dicing of the present invention, the surface layer and/or the back layer may be a single layer or a multilayer. The base film for dicing of the present invention can be provided with a plurality of surface layers and/or back layers, if necessary.

When the surface layer and/or back layer are multi-layered, they are expressed as surface layer-1, surface layer-2, surface layer-3, etc. in order from the outermost layer side, and back layer-1, back layer in order from the backmost layer side. Represented as layer-2, back layer-3, etc.

(1-3) Intermediate layer The intermediate layer is made of a resin composition containing polyurethane resin (PU).

Preferably, the PU is a thermoplastic polyurethane resin (TPU).

When the base film for dicing has an intermediate layer made of a resin composition containing polyurethane resin (PU), expandability can be improved.

Since the base film for dicing has an intermediate layer made of a resin composition containing polyurethane resin (PU), it can be used under low temperature conditions and high speed conditions, for example, when cutting (dividing) a semiconductor wafer and a die bond layer after stealth dicing. The dicing film can be stretched well even when expanding is performed.

(i) Polyurethane resin (PU)
It is preferable to use thermoplastic polyurethane resin (TPU) as the polyurethane resin (PU). TPU is obtained by reacting polyisocyanate, polyol, and chain extender, and consists of soft segments created by the reaction of polyol and polyisocyanate and hard segments created by the reaction of chain extender and polyisocyanate. It is a block copolymer.

Examples of the polyisocyanate include diphenylmethane diisocyanate, hexamethylene diisocyanate, toridine diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and the like. Among these, diphenylmethane diisocyanate and/or hexamethylene diisocyanate are preferred in terms of the abrasion resistance of the thermoplastic polyurethane resin.

Examples of the polyol include polytetramethylene ether glycol, polyester polyol, lactone polyester polyol, and the like. Polyester polyols are obtained by polycondensation reaction of dicarboxylic acids and diols.

Specific examples of diols used in the production of polyester polyols include ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, etc. Either alone or in combination.

Further, dicarboxylic acids used in the present invention include adipic acid, sebacic acid, etc., and these may be used alone or in combination.

Among these polyols, polytetramethylene ether glycol is preferred because the thermoplastic polyurethane resin can provide high impact resilience. Further, the number average molecular weight of such a polyol is preferably 1,000 to 4,000, particularly preferably 2,000 to 3,000.

Examples of chain extenders include aliphatic linear diols having 2 to 6 carbon atoms such as ethanediol, 1,4-butanediol, and 1,6-hexanediol; 1,4-bis(hydroxyethoxy); Examples include benzene. Some amines such as hexamethylene diamine, isophorone diamine, tolylene diamine, monoethanolamine, etc. can also be used in combination. Among these, aliphatic linear diols having 2 to 6 carbon atoms are preferred from the viewpoint of the abrasion resistance of the thermoplastic polyurethane resin.

The density of the thermoplastic polyurethane resin is preferably about 1.1 to 1.5 g/cm ³ , more preferably about 1.1 to 1.3 g/cm ³ .

The thermoplastic polyurethane resin can be manufactured using the above-mentioned raw materials using a known method such as a one-shot method or a prepolymer method.

Examples of the PU include Pandex manufactured by DIC Covestro Polymer Co., Ltd. and Miractran manufactured by Nippon Miractran Co., Ltd.

The resin composition constituting the intermediate layer may include (ii) a polyethylene resin in addition to the (i) PU.

(ii) Polyethylene resin
As the polyethylene resin, resins that can be used in the surface layer can be used.

The same resin as the polyethylene resin used in the surface layer may be used for the intermediate layer, or a resin different from the polyethylene resin used in the surface layer may be used. As the polyethylene resin, it is preferable to use ethylene-methacrylic acid copolymer (EMAA) together with the above-mentioned PU.

When the intermediate layer contains a polyethylene resin, the content thereof is preferably 0 to 80% by weight, and preferably 0 to 70% by weight.

When the content of the polyethylene resin is in the range of 0 to 80% by weight, the base film for dicing has good expandability, that is, good tensile properties.

(1-4) Layer structure of base film for dicing The base film for dicing of the present invention includes a structure in which a surface layer/intermediate layer/back layer are laminated in this order.

The surface layer is the wafer contact side and is the layer that comes into contact with the adhesive layer.

For the intermediate layer, a layer (single layer) may be formed using each resin alone, a layer (single layer) may be formed using a mixture of resins, or a layer (multilayer) may be formed for each resin. good.

In the substrate film for dicing of the present invention, it is preferable that the surface layer and/or the back layer be a single layer or a multilayer. The front and back layers may be made of LDPE, EVA, etc., and may form a layer (single layer) with each resin, a layer (single layer) with a mixture of resins, or a layer (multilayer) with each resin. may be formed.

The overall thickness of the substrate film for dicing of the present invention is preferably about 50 to 300 μm, more preferably about 70 to 200 μm, and even more preferably about 80 to 150 μm. By setting the entire thickness of the dicing base film to 50 μm or more, it is possible to protect the semiconductor wafer from impact when dicing the semiconductor wafer.

The ratio of the thickness of the front layer and back layer to the total thickness of the base film for dicing is preferably about 4 to 80%, more preferably about 10 to 60%.

The ratio of the thickness of the intermediate layer to the total thickness of the base film for dicing is preferably about 20 to 96%, more preferably about 40 to 90%.

As a specific example of the base film for dicing, a case where the total thickness of the base film for dicing is about 60 to 100 μm will be explained.

The thickness of the surface layer and the back layer is preferably about 2 to 44 μm each, more preferably about 10 to 38 μm each. When the surface layer and the back layer are multi-layered, each layer may be formed to have a total thickness within the above-mentioned thickness range.

The thickness of the intermediate layer is preferably about 12 to 96 μm, more preferably about 24 to 80 μm. When the intermediate layer is a multilayer, each layer may be formed to have a total thickness within the above-mentioned thickness range.

Example of 3 types and 5 layers (Surface layer-1/Surface layer-2/Middle layer/Back layer-2/Back layer-1)
In the example of 5 layers of 3 types, as mentioned above, the total thickness of surface layer-1 and surface layer-2 is within the thickness range of the surface layer above, and similarly, the total thickness of back layer-1 and back layer-2 is within the range of the thickness of the surface layer above. is the range of the thickness of the backing layer.

The same type of polyethylene resin may be used for the surface layer-1 and the surface layer-2, or different types of polyethylene resins may be used for the surface layer-1 and the surface layer-2.

For back layer-1 and back layer-2, the same type of polyethylene resin may be used, or different types of polyethylene resin may be used.

When using the same type of polyethylene resin, for example, when using EVA, the EVA used for the surface layer-2 and the back layer-2 has a lower vinyl group content ( It is preferable to use EVA with a high VA content.

For the surface layer-1 and the back layer-1, it is preferable to use EVA with a VA content of about 5 to 15% by weight, and more preferably EVA with a VA content of about 7 to 13% by weight.

For the surface layer-2 and the back layer-2, it is preferable to use EVA with a VA content of about 15 to 33% by weight, and more preferably to use EVA with a VA content of about 28 to 33% by weight.

In addition, from the viewpoint of MFR, it is preferable to use EVA for the surface layer-2 and the back layer-2, which has a higher melt flow rate (MFR) than that for the surface layer-1 and the back layer-1.

For the surface layer-1 and the back layer-1, the MFR of EVA at 190°C is preferably about 0.1 g/10 minutes to 10 g/10 minutes, more preferably about 5 g/10 minutes to 10 g/10 minutes.

For the surface layer-2 and the back layer-2, the MFR of EVA at 190°C is preferably about 10 g/10 minutes to 40 g/10 minutes, more preferably about 12 g/10 minutes to 35 g/10 minutes.

(2) Manufacturing method of base film for dicing The base film for dicing of the surface layer/intermediate layer/back layer can be manufactured by multilayer coextrusion molding of resin compositions for the surface layer, intermediate layer, and back layer. Specifically, the resin composition for the surface layer, the resin composition for the intermediate layer, and the resin composition for the back layer are manufactured by coextrusion molding so that they are laminated in the order of surface layer/intermediate layer/back layer. Can be done.

Furthermore, when the surface layer and the back layer are made into a multilayer structure, the resin compositions for each surface layer and the back layer are put into the respective extruders, and for example, the resin composition for the surface layer-1/surface layer-2/intermediate layer/back layer is formed. It can be manufactured by coextrusion molding so that the layers are laminated in the order of -2/back layer -1.

An antistatic agent can be further added to the resin composition constituting the surface layer, if necessary. The same applies to the back layer.

The resins for each layer described above are supplied in this order to a screw extruder, extruded into a film from a multilayer T-die at 180 to 240°C, and cooled while passing through cooling rolls at 30 to 70°C. It will be picked up without stretching. Alternatively, the resin for each layer may be once obtained as pellets and then extruded as described above.

The reason why the film is not stretched substantially during take-off is to effectively expand the film after dicing. This "substantially no stretching" includes no stretching or a slight amount of stretching that does not adversely affect the expansion of the dicing film. Normally, when taking off the film, it is enough to pull it to an extent that does not cause sagging.

(3) Manufacture of dicing film The dicing film of the present invention can be manufactured according to well-known techniques. For example, by dissolving the adhesive constituting the adhesive layer in a solvent such as an organic solvent, applying this onto a base film for dicing, and removing the solvent, a film having a base film/adhesive layer structure can be obtained. Can be done.

A die bond film is produced by dissolving the resin composition constituting the die bond layer in a solvent such as an organic solvent, applying the solution onto another film (release film), and removing the solvent.

Furthermore, a dicing film is produced by stacking the pressure-sensitive adhesive layer and the die-bonding layer so as to face each other. Thereby, a film having the structure of base film/adhesive layer/die bond layer can be obtained. At this stage, the die bond layer is bonded to the semiconductor wafer and the adhesive layer in a weak (pseudo) bonded state.

After expansion, the separated semiconductor chip and die bond layer are stacked with a predetermined package or semiconductor chip, heated to a temperature at which the die bond layer is strongly bonded, and bonded.

EXAMPLES Below, the present invention will be explained in more detail using Examples, but the present invention is not limited to these Examples.

(1) Raw materials for the base film for dicing Table 1 shows the raw materials for the base film for dicing.

[Explanation of abbreviations]
PE-1~9: Polyethylene resin 1~9
SEBS: Styrene-butadiene copolymer hydrogenated product
(Styrene-ethylene-butylene-styrene copolymer)
TPU: Thermoplastic polyurethane (PU)
Amorphous PO: Amorphous polyolefin
LDPE: Branched low density polyethylene
EVA: Ethylene-vinyl acetate copolymer
VA content: Vinyl acetate content percentage
EMAA: Ethylene-methacrylic acid copolymer
MAA content: methacrylic acid content
St content: Styrene content ratio (Content of vinyl aromatic hydrocarbon (St) component in vinyl aromatic hydrocarbon resin)

(2) Production of base film for dicing of surface layer/intermediate layer/back layer A resin composition is blended with each component and composition so that the surface layer/intermediate layer/back layer (3 layers) shown in Table 2 is obtained. A base film for dicing was produced.

The resin compositions constituting each layer were put into respective extruders adjusted to 220°C, extruded and laminated using T-dies at 220°C in the order of surface layer/intermediate layer/back layer, and extruded at 30°C. A flat three-layer film was obtained by coextrusion on a chill roll with circulating cooling water.

(3) Production of base film for dicing of surface layer-1/surface layer-2/intermediate layer/back layer-2/back layer-1 as described in Tables 3 and 4. -2/Back layer-1 (5 layers) A resin composition was blended with each component and composition to produce a base film for dicing.

The resin compositions constituting each layer were put into respective extruders adjusted to 220°C, and the resin compositions were placed in the order of surface layer-1/surface layer-2/intermediate layer/back layer-2/back layer-1 at 220°C. The mixture was extruded and laminated using a T-die at 30°C, and coextruded onto a chill roll circulating cooling water at 30°C to obtain a flat 5-layer film.

(4) Evaluation of base film for dicing (4-1) Low temperature expandability (Ex property)
<Evaluation method>
(Measurement of tensile elongation)
The film was processed at a tensile speed of 200 mm/min in the MD direction (extrusion direction of film forming) and TD direction (width direction of the film formed by film forming) so that the distance between chucks was 40 mm with a width of 10 mm. The tensile elongation of the film was measured using the film sample.

(Measurement of 25% modulus)
The film was processed at a tensile speed of 200 mm/min in the MD direction (extrusion direction of film forming) and TD direction (width direction of the film formed by film forming) so that the distance between chucks was 40 mm with a width of 10 mm. An SS curve (stress-strain curve) was obtained using the film sample.

The stress value at an elongation rate of 25% was read from each of the obtained SS curves.

<Evaluation criteria>
(a) Low temperature expandability (low temperature Ex property)
○: The elongation rate is 100% or more when a tensile test is performed.
×: The film elongation rate is less than 100% when subjected to a tensile test.

(B) Uniform expandability (uniform Exability)
The ratio of the stress value at an elongation rate of 25% in the MD direction and the stress value at an elongation rate of 25% in the TD direction was determined, and was defined as the modulus ratio (MD/TD).
○: Modulus ratio (MD/TD) is less than 1.5.
×: Modulus ratio (MD/TD) is 1.5 or more.

When the modulus ratio (MD/TD) is within the above range, the base film for dicing exhibits good uniform expandability (uniform Ex performance) under low temperature conditions of -15 to 5°C.

(4-2) Low-temperature, high-speed expandability (low-temperature, high-speed Ex properties)
<Evaluation method>
(Measurement of elongation at break (maximum elongation) (%))
Tensile test: Using "HYDROSHOT HITS-T10" manufactured by Shimadzu Corporation, processing was performed at a tensile speed of 250 mm/sec in an environment of -15 ± 2 ° C so that the distance between chucks was 10 mm with a width of 25 mm. The film sample was stretched in the MD and TD directions until it broke.

An SS curve (stress-strain curve) was created from the load and elongation data plot, and the elongation at break (maximum elongation) was calculated.

<Evaluation criteria>
(High-speed tensile test evaluation (mechanical properties))
○: Tensile elongation at break in MD and TD directions is 120% or more.
×: Tensile elongation at break in MD and TD directions is less than 120%.

In this evaluation method, the tensile speed is set at 250 mm/sec and a tensile test is performed to evaluate expandability under high-speed conditions in addition to low-temperature conditions. The tensile elongation at break in the MD and TD directions of the film is 120% or more, so the film is suitable for expansion under low temperature conditions (-15 to 5℃) and high speed conditions, for example after stealth dicing. Stretch to.

(4-3) Heat shrink property (HS property)
Condition 1 - Tensile test: Using "Autograph AG-500NX TRAPEZIUM The processed film sample was stretched by 200% in both the MD and TD directions.

Condition 2 - Shrinkage test: Using a "humidifier TBP105DA" manufactured by Mitsubishi Heavy Industries Refrigeration Co., Ltd., the sample was heated for 5 seconds at a set temperature of 80°C.

<Evaluation method>
A film strip sample with a length of 100 mm (marker interval 40 mm + gripping margin (30 mm each on top and bottom)) and a width of 10 mm was prepared and stretched under Condition 1 above.

After holding the 200% stretched state for 10 seconds, the chuck was returned to its original position, the chuck was released, and the sample was contracted under Condition 2 above.

The gauge line interval L [mm] after shrinkage was measured, and the recovery rate was calculated using the following formula.

Recovery rate [%] = {(120-L)/80} x 100
The recovery rate was measured in both the MD direction and the TD direction, and this was expressed as heat shrink property (HS property).

<Evaluation criteria>
(A) Heat shrink property (HS property)
○: Recovery rate is 70% or more due to heat shrink.
More preferably, the recovery rate is 90 to 110%.
×: Recovery rate is less than 70% due to heat shrink.

When the recovery rate in the MD and TD directions is within the above range, the base film for dicing exhibits good heat shrink properties (HS properties) in an environment of 80°C.

(a) Uniform heat shrink property (uniform HS property)
○: The ratio of the recovery rate in the MD direction to the recovery rate in the TD direction (MD/TD) is less than 1.2.
The recovery rate ratio (MD/TD) is more preferably 0.9 to 1.15.
×: Recovery rate ratio (MD/TD) is 1.2 or more.

When the ratio of recovery rate (MD/TD) is within the above range, the base film for dicing exhibits good uniform heat shrink properties (uniform HS properties) under the condition of 80°C.

The dicing base films of the present invention (Examples 1 to 12) were uniformly stretched even when expanded under low temperature conditions.

The base film for dicing of the present invention (Example) had a significantly larger heat shrink property (HS property) value than that of the comparative example. In other words, the base film for dicing of the present invention had better heat shrink properties.

The low-temperature expandability (Ex properties) of the dicing base films of the present invention (example) and comparative example were both within an acceptable range.

The substrate film for dicing of the present invention (Example) had better low-temperature, high-speed expandability (low-temperature, high-speed Ex properties) than the comparative example.

(5) Consideration Heat shrink property When the base film for dicing of the present invention is used, the dicing film (sheet) can shrink the slack portion by heating it even after the expanding process, eliminating the slack. can do.

When the base film for dicing of the present invention is used, the dicing film (sheet) has a particularly high recovery rate due to heat shrinkage.

By using the dicing base film of the present invention, used dicing films can be collected more quickly and easily into a rack. In other words, the base film for dicing of the present invention has high thermal recovery properties, and moreover, the dicing film recovers uniformly. In other words, the heat shrink property is well exhibited, and the rack recovery property is excellent. Further, products using the dicing base film of the present invention do not collide with each other and do not have defects.

Expandability When the base film for dicing of the present invention is used, even when expanding is carried out under low temperature conditions, the expandability is good and the dicing film is uniformly stretched. When the base film for dicing of the present invention is used, the semiconductor wafer and the die-bonding layer can be cut (separated) at once in a good manner during expansion performed under low-temperature conditions.

When the base film for dicing of the present invention is used, especially when cutting (dividing) a semiconductor wafer and a die bond layer after stealth dicing, even when expanding is performed under low temperature conditions and high speed conditions, expandability can be improved. is good, and the dicing film stretches well. When the dicing base film of the present invention is used, the semiconductor wafer and the die bond layer can be well cut (separated) at once during expansion performed under low temperature conditions and high speed conditions.

When the base film for dicing of the present invention is used, a sheet with higher expandability and shrinkability can be obtained, as semiconductor products are becoming smaller and more expandable (expandability) is required in sheets.

Claims (5)

A base film for dicing including a structure in which a surface layer/intermediate layer/back layer are laminated in this order,
The surface layer and the back layer are made of a resin composition containing polyethylene resin,
The intermediate layer is made of a resin composition containing a polyurethane resin.
Base film for dicing. The substrate film for dicing according to claim 1, wherein the surface layer and/or back layer is a single layer or a multilayer. The polyethylene resin may be branched low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene- At least one resin selected from the group consisting of ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-methyl methacrylate copolymer (EMMA), ethylene-methacrylic acid copolymer (EMAA), and ionomer resin The base film for dicing according to claim 1 or 2. The base film for dicing according to any one of claims 1 to 3, wherein the polyurethane resin is a thermoplastic polyurethane resin (TPU). A dicing film comprising a pressure-sensitive adhesive layer and a die-bonding layer provided in this order on the surface layer side of the base film for dicing according to any one of claims 1 to 4.