JP5889892B2 - Method for manufacturing adhesive sheet and electronic component - Google Patents

Description

  The present invention relates to an adhesive sheet and a method for producing an electronic component using the adhesive sheet.

  For semiconductor wafers, the adhesive sheet is usually bonded after the circuit is formed, and then cut into element pieces (dicing), washed, dried, stretched (expanded) the adhesive sheet, and peeled off the element pieces from the adhesive sheet. (Pickup), mounting and other processes. The pressure-sensitive adhesive sheet (dicing tape) used in these processes has sufficient adhesive force against the cut element chips (chips) from the dicing process to the drying process, but has no adhesive residue during the pick-up process. It is desired that the adhesive strength is reduced to a certain extent.

  As the pressure-sensitive adhesive sheet, there is one in which a pressure-sensitive adhesive layer that undergoes a polymerization and curing reaction by ultraviolet light or the like is applied on a base material that is transparent to active light such as ultraviolet light and / or electron beam. In this pressure-sensitive adhesive sheet, after the dicing step, ultraviolet light or the like is irradiated to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is polymerized and cured to reduce the pressure-sensitive adhesive force, and then a cut chip is picked up.

  As such a pressure-sensitive adhesive sheet, Patent Document 1 and Patent Document 2 disclose a compound having a photopolymerizable unsaturated double bond in its molecule (polyfunctional) that can be three-dimensionally reticulated on the substrate surface by, for example, actinic rays. An adhesive sheet coated with an adhesive containing an oligomer) is disclosed.

JP-A-60-196956 JP 60-223139 A

  In the pick-up process, the chip is peeled from the pressure-sensitive adhesive sheet by pushing the needle pin against the pressure-sensitive adhesive sheet side of the semiconductor wafer after dicing to push up the cut and separated chip.

  At this time, cracking of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet may occur due to the needle pin being pushed up. When the pressure-sensitive adhesive layer is cracked, the broken pressure-sensitive adhesive layer adheres to the chip (adhesive residue), causing contamination and defective mounting processes.

  Therefore, the main object of the present invention is to provide a pressure-sensitive adhesive sheet in which the adhesive strength before and after curing of the ultraviolet curable pressure-sensitive adhesive layer is in a preferable range and does not cause cracking of the pressure-sensitive adhesive layer during pickup.

In order to solve the above problems, the present invention is a pressure-sensitive adhesive sheet comprising a base material and a photocurable pressure-sensitive adhesive layer formed on one side of the base material, and the photo-curing of the pressure-sensitive adhesive layer measured under the following conditions Adhesiveness whose storage elastic modulus after is 0.5-2.0 (x10 < ⁸ > Pa), and the value of the storage elastic modulus after photocuring of an adhesive layer / the storage elastic modulus of a base material is 1-3 Provide a sheet.
Frequency: 1Hz
Distortion: 0.1%
Temperature: 30 ° C

  The inventors of the present invention first paid attention to the storage elastic modulus after photocuring of the pressure-sensitive adhesive layer, and found that the pressure-sensitive adhesive layer cracks when the storage elastic modulus falls outside the specified range. However, even when the storage elastic modulus is within the specified range, an example of cracking of the pressure-sensitive adhesive layer has been found, and further investigation has been carried out. As a result, the storage elastic modulus after photocuring of the pressure-sensitive adhesive layer / base material It was found that such a crack occurs when the storage elastic modulus value of is out of the specified range. Based on these findings, as described above, the storage elastic modulus after photocuring of the pressure-sensitive adhesive layer is within a specified range, and the storage elastic modulus after photocuring of the pressure-sensitive adhesive layer / the storage elastic modulus of the base material. It was found that by making the value within the specified range, cracking of the pressure-sensitive adhesive layer could be prevented, and the present invention was completed.

In this pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer comprises (meth) acrylic acid ester polymer (A), bisphenol A type epoxy acrylate (B), photopolymerization initiator (C), curing agent ( D), (B) is a 3-4 functional acrylate, has a molecular weight of 1000-2000, and (D) has a trifunctional or higher functional isocyanate group, and is a hydroxyl group in the pressure-sensitive adhesive composition. The molar ratio of / isocyanate group is preferably 0.6 to 1.2.
The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 700,000 to 1,500,000.
Moreover, the said storage elastic modulus of the said base material is 0.5-2.0 (* 10 < ⁸ > Pa), for example.
Moreover, it is preferable that the storage elastic modulus after photocuring of the said adhesive is 0.5-1.5 (x10 < ⁸ > Pa).

  The present invention also includes a bonding step of bonding an electronic component to the pressure-sensitive adhesive sheet, a dicing step of dicing the electronic component after the bonding step, and a base material pressure-sensitive adhesive layer after the dicing step. There is also provided a method of manufacturing an electronic component, including a pickup step of irradiating light from a non-surface side and picking up the electronic component from an adhesive layer.

  According to the present invention, there is provided a pressure-sensitive adhesive sheet in which the adhesive strength before and after curing of the ultraviolet curable pressure-sensitive adhesive layer is in a preferable range and does not cause cracking of the pressure-sensitive adhesive layer during pickup.

It is a cross-sectional schematic diagram for demonstrating the bonding process of the structure of the adhesive sheet which concerns on this invention, and the manufacturing method of the electronic component concerning this invention. It is a cross-sectional schematic diagram for demonstrating the dicing process of the manufacturing method of the electronic component which concerns on this invention. It is a cross-sectional schematic diagram for demonstrating the pick-up process of the manufacturing method of the electronic component which concerns on this invention. It is a cross-sectional schematic diagram for demonstrating the electronic component after a pick-up process.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the drawings. In addition, embodiment described below shows an example of typical embodiment of this invention, and, thereby, the range of this invention is not interpreted narrowly.

1. Adhesive Sheet (1) Substrate FIG. 1 is a schematic cross-sectional view showing the configuration of an adhesive sheet according to the present invention. The pressure-sensitive adhesive sheet 1 includes a base material 2 and a photocurable pressure-sensitive adhesive layer 3 laminated on one side of the base material 2.

  The base material 2 is made of a material having transparency to actinic rays (hereinafter also simply referred to as “light”) such as ultraviolet rays and / or electron beams. Examples of the material of the substrate 2 include the following. Polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid-acrylic acid ester film, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, ethylene-acrylic acid copolymer. An ionomer resin obtained by crosslinking a polymer such as an ethylene- (meth) acrylic acid copolymer and an ethylene- (meth) acrylic acid- (meth) acrylic acid ester copolymer with a metal ion, or a mixture or copolymer of these resins. Coalescence. In this specification, (meth) acrylic acid means acrylic acid and methacrylic acid, and (meth) acryloyl group means acryloyl group and methacryloyl group.

  The base material 2 may be a single layer or a multilayer film or sheet made of the above material, or may be a laminate of films made of different materials.

  The substrate 2 is preferably subjected to an antistatic treatment. As the antistatic treatment, there are a treatment for adding an antistatic agent to the substrate 2, a treatment for applying an antistatic agent to the surface of the substrate 2, and a treatment by corona discharge.

  As the antistatic agent, for example, a quaternary amine salt monomer can be used.

  Examples of the quaternary amine salt monomer include dimethylaminoethyl (meth) acrylate quaternary chloride, diethylaminoethyl (meth) acrylate quaternary chloride, methylethylaminoethyl (meth) acrylate quaternary chloride, p-dimethyl. Examples include aminostyrene quaternary chloride and p-diethylaminostyrene quaternary chloride. Of these, dimethylaminoethyl methacrylate quaternary chloride is preferred.

  The base material 2 has a thickness of 50 to 200 μm, preferably 70 to 150 μm.

The base material 2 has a storage elastic modulus G ′ of, for example, 0.2 to 2.0 (× 10 ⁸ Pa) or 0.5 to 2.0 (× 10 ⁸ Pa). Specifically, the storage elastic modulus G ′ is, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1 .1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 (× 10 ⁸ Pa), illustrated here It may be within a range between any two of the numerical values. The storage elastic modulus G ′ of the substrate 2 can be adjusted by appropriately selecting and changing the material and thickness of the substrate 2.

(2) Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 3 may be a photocurable type, and its composition is not particularly limited. In one example, the pressure-sensitive adhesive layer 3 is composed of (meth) acrylic acid ester polymer (A), bisphenol. It can be formed by an adhesive composition containing an A-type epoxy acrylate (B), a photopolymerization initiator (C), and a curing agent (D).

  The (meth) acrylic acid ester polymer (A) is a polymer obtained by polymerizing a (meth) acrylic acid ester monomer, and preferably has a weight average molecular weight of 500,000 to 2,000,000, and 700,000. More preferably, it is ˜1.5 million. Further, the (meth) acrylic acid ester polymer may contain a vinyl compound monomer other than the (meth) acrylic acid ester monomer. In addition, in this specification, "weight average molecular weight" is the value measured as a polystyrene conversion value by the gel permeation chromatography method (GPC).

As a monomer of (meth) acrylic acid ester, n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, octyl (meth) acrylate, 2 -Ethylhexyl acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, tridecyl (meth) acrylate, myristyl ( (Meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, benzyl (meth) acrylate , Methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxymethyl (meth) acrylate, and ethoxy-n-propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) An acrylate, 2-hydroxybutyl (meth) acrylate, etc. are mentioned. Yes, vinyl compound monomers copolymerizable with (meth) acrylic acid ester monomers include vinyl acetate, vinyl alcohol, (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid Examples include acid, acrylamide N-glycolic acid, and cinnamic acid.

  The bisphenol A type epoxy acrylate (B) is represented by the following formula.

(In the formula, R represents a hydrogen atom or a (meth) acrylate group. N represents an integer of 1 or more.)

  The bisphenol A type epoxy acrylate (B) is preferably a 3- to 4-functional acrylate, and preferably has a molecular weight of 1000 to 2000.

  If the acrylate of the bisphenol A type epoxy acrylate (B) is less than trifunctional, the peelability (pickup property) between the chip and the sheet at the time of pickup tends to decrease, and if it exceeds 4 functionalities, the adhesive layer cracks. Tend to.

  Further, if the molecular weight of the bisphenol A type epoxy acrylate (B) is less than 1000, the pressure-sensitive adhesive layer tends to crack at the time of pickup, and if it exceeds 2000, the pickup property tends to be lowered.

  It is preferable that the compounding quantity of bisphenol A type epoxy acrylate (B) shall be 20 to 200 mass parts with respect to 100 mass parts of (meth) acrylic acid ester polymer (A). If the blending amount is less than 20 parts by mass, the pick-up property tends to decrease, and if it exceeds 200 parts by mass, the adhesive layer is scraped up in the dicing process, and the adhesive layer thus scooped up is accurate in the pickup process. May cause degradation. Specifically, the blending amount is, for example, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). It may be within the range between any two of the numerical values exemplified here.

  As the photopolymerization initiator (C), benzoin, benzoin alkyl ethers, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones or xanthones are used.

  Examples of benzoin include benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin propyl ether. Examples of acetophenones include benzoin alkyl ethers, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, and the like. Anthraquinones include 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 1-chloroanthraquinone and the like. Examples of thioxanthones include 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone. Examples of ketals include acetophenone dimethyl ketal, benzyl dimethyl ketal, benzyl phenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, and β-chloranthraquinone.

  The photopolymerization initiator (C) may be used in combination with one or more conventionally known photopolymerization accelerators, if necessary. A benzoic acid type | system | group, a tertiary amine, etc. can be used for a photoinitiator. Examples of the tertiary amine include triethylamine, tetraethylpentamine, dimethylamino ether and the like.

  It is preferable that the compounding quantity of a photoinitiator (C) shall be 1 to 5 mass parts with respect to 100 mass parts of (meth) acrylic acid ester polymer (A). If the blending amount is less than 1 part by mass, the pick-up property tends to decrease, and if it exceeds 5 parts by mass, the pressure-sensitive adhesive layer tends to crack.

  As the curing agent (D), trimers such as aromatic diisocyanate, alicyclic diisocyanate, and aliphatic diisocyanate are used. Further, trimethylolpropane adducts of these diisocyanates, burettes reacted with water, trimers having an isocyanurate ring, and the like are also preferably used.

  Examples of the aromatic diisocyanate include tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, xylylene diisocyanate, and the like. Examples of the alicyclic diisocyanate include isophorone diisocyanate and methylene bis (4-cyclohexyl isocyanate). Examples of the aliphatic diisocyanate include hexamethylene diisocyanate and trimethylhexamethylene diisocyanate.

  The compounding quantity of a hardening | curing agent (D) is determined so that the molar ratio of the hydroxyl group / isocyanate group in an adhesive composition may be 0.6-1.2. If the molar ratio is less than 0.6, the pressure-sensitive adhesive layer tends to crack, and if it exceeds 1.2, the tape quality may be deteriorated due to a change with time during storage. Specifically, this molar ratio is, for example, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, and any one of the numerical values exemplified here is 2 It may be within a range between the two.

  Various additives such as a tackifier, a release agent, a softener, an anti-aging agent, a filler, an ultraviolet absorber, and a light stabilizer may be added to the pressure-sensitive adhesive composition.

  As the tackifier, rosin resin, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, hydrogenated petroleum resin, chroman indene resin, styrene resin, xylene resin and a mixture of these resins are used. These are resins that do not contain hydroxyl groups in their chemical structure.

  Although the thickness of the adhesive layer 3 is not specifically limited, For example, it is 1-100 micrometers, Preferably it is 2-40 micrometers. If the pressure-sensitive adhesive layer 3 is too thick, the pressure-sensitive adhesive force becomes too high and the pick-up property is lowered. On the other hand, if the pressure-sensitive adhesive layer 3 is too thin, the adhesive strength becomes too low, the chip retainability during dicing is lowered, and peeling may occur between the ring frame and the sheet. Specifically, the thickness of the pressure-sensitive adhesive layer 3 is, for example, 1, 2, 5, 10, 15, 20, 40, 50, 100 μm, and is within a range between any two of the numerical values exemplified here. May be.

The pressure-sensitive adhesive layer 3 has a storage elastic modulus G ′ after photocuring of 0.5 to 2.0 (× 10 ⁸ Pa) and 0.5 to 1.5 (× 10 ⁸ Pa). It is preferable to do so. If the storage elastic modulus G ′ is less than 0.5 × 10 ⁸ Pa, the peelability between the sheet and the adherend in the pick-up process tends to decrease, and if it exceeds 2.0 × 10 ⁸ Pa, the needle pin Cracking of the pressure-sensitive adhesive layer due to push-up tends to occur. Specifically, the storage elastic modulus G ′ after the polymerization curing reaction of the pressure-sensitive adhesive layer 3 is, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1. 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 (× 10 ⁸ Pa), and the numerical values exemplified here It may be within the range between any two.

  The storage elastic modulus G ′ after photocuring of the pressure-sensitive adhesive layer 3 is the blending amount of bisphenol A type epoxy acrylate (B), photopolymerization initiator (C), curing agent (D), (meth) acrylic acid ester polymer. By setting the weight average molecular weight of (A), the functional number and molecular weight of the bisphenol A type epoxy acrylate (B) to the above-mentioned numerical values, the desired values can be set. Among these, it is important to set the functional number and molecular weight of the bisphenol A type epoxy acrylate (B) to predetermined values in order to obtain the desired post-curing elasticity by controlling the reaction amount of the photopolymerization reaction.

  The value of the ratio of the storage elastic modulus after photocuring of the pressure-sensitive adhesive layer / the storage elastic modulus of the base material is 1 to 3, and preferably 2 to 3. That is, it is important that the storage elastic modulus of the pressure-sensitive adhesive layer after photocuring is the same as or slightly larger than that of the substrate. It was experimentally found that adhesive cracking is prevented by setting this value within such a range. In addition, when the storage elastic modulus after photocuring of an adhesive layer was smaller than the storage elastic modulus of a base material, or when the value of the said ratio was larger than 3, the crack of the adhesive occurred.

2. Electronic Component Manufacturing Method (1) Bonding Step FIGS. 1 to 4 show cross-sectional schematic diagrams of the steps of the electronic component manufacturing method according to the present invention. The electronic component manufacturing method according to the present invention includes a bonding step of bonding the electronic component to the above-described pressure-sensitive adhesive sheet 1, a dicing step of dicing the electronic component, irradiating ultraviolet rays from the substrate 2 side, A pickup step of picking up from the pressure-sensitive adhesive layer 3.

  In the bonding step, a wafer or package 4 (hereinafter referred to as “wafer 4”) is bonded and fixed to the surface of the pressure-sensitive adhesive sheet 1, and the pressure-sensitive adhesive sheet 1 is fixed to the ring frame 5. In FIG. 1, the state of the adhesive sheet 1 and the wafer 4 after a bonding process is shown. The wafer 4 may be a conventional general-purpose wafer such as a silicon wafer, a gallium nitride wafer, a silicon carbide wafer, or a sapphire wafer.

(2) Dicing process In the dicing process, the wafer 4 after the bonding process is diced with a dicing blade 6. In FIG. 2, the state of the adhesive sheet 1 and the wafer 4 after a dicing process is shown. Reference numeral 61 in the drawing is a notch due to dicing.

(3) Pickup Process In the pickup process, the wafer 4 after the dicing process is picked up from the adhesive layer 3. FIG. 3 shows the state of the pressure-sensitive adhesive sheet 1 and the wafer 4 in the pickup process. FIG. 4 shows the state of the chip 41 after the pickup process.

  A specific procedure of the pickup process will be described. First, light is irradiated from the base material 2 side of the pressure-sensitive adhesive sheet 1. As the ultraviolet light source, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, or a metal halide lamp can be used. Moreover, an electron beam, an alpha ray, a beta ray, and a gamma ray can be used as an electron beam light source.

  The pressure-sensitive adhesive layer 3 is three-dimensionally reticulated and cured by light irradiation, and the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer 3 is reduced. Due to the decrease in the adhesive strength of the pressure-sensitive adhesive layer 3, peeling between the chip 41 and the pressure-sensitive adhesive layer 3 is facilitated, and the chip 41 can be picked up in the subsequent procedure.

  Next, the pressure-sensitive adhesive sheet 1 is radially expanded (expanded) to increase the interval between the tips 41, and then the tips 41 are pushed up with a needle pin or the like (not shown). Thereafter, the chip 41 is adsorbed by a vacuum collet or air tweezers (not shown), and peeled off from the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1 and picked up.

  At this time, since the pressure-sensitive adhesive sheet 1 exhibits excellent followability with respect to the needle pins pressed against the sheet, the occurrence of cracks in the pressure-sensitive adhesive layer 3 due to the needle pins being pushed up is effectively prevented. Therefore, the broken adhesive layer does not adhere to the chip (adhesive residue) and does not cause contamination or a defective mounting process.

  In the procedure after the pickup process of the electronic component manufacturing method according to the present invention, first, the picked-up chip 41 is mounted on the lead frame 7 via a die attach paste. After mounting, the die attach paste is heated, and the chip 41 and the lead frame 7 are heat bonded. Thereafter, the chip 41 mounted on the lead frame 7 is molded with resin (not shown). The lead frame 7 may be replaced with a circuit board on which a circuit pattern is formed.

<Examples and comparative examples>
A pressure-sensitive adhesive composition was prepared according to the formulation shown in Table 1. A base film having a thickness of 100 μm made of an ionomer resin (Mitsui / DuPont Polychemical Co., Ltd., High Milan 1855) mainly composed of a Zn salt of an ethylene-methacrylic acid-methacrylic acid alkyl ester copolymer was prepared. This ionomer resin contains Zn ²⁺ ions and has a melting point of 96 ° C. and an MFR (melt flow rate) value of 1.5 g / 10 minutes measured at a temperature of 210 ° C. according to JIS K7210.

  The pressure-sensitive adhesive composition was coated on a PET separator film using a comma coater so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, dried at 100 ° C. for 3 minutes, and then laminated on the base film to form a pressure-sensitive adhesive sheet. Obtained.

  The following were used for the (meth) acrylic acid ester polymer (A), bisphenol A type epoxy acrylate (B), photopolymerization initiator (C), and curing agent (D) described in the table.

(1) (Meth) acrylic acid ester polymer (A)
(A) -1: A commercial product (made by Showa Denko KK, product name Vinylol SPV-8141) made of a copolymer having a weight average molecular weight of 500,000 and obtained by solution polymerization.
(A) -2: In-house polymerized product made of a copolymer having a weight average molecular weight of 700,000 and obtained by solution polymerization.
(A) -3: An in-house polymerized product made of a copolymer having a weight average molecular weight of 1,500,000 and obtained by solution polymerization.
(A) -4: In-house polymerized product made of a copolymer having a weight average molecular weight of 2 million and obtained by solution polymerization.

(2) Bisphenol A type epoxy acrylate (B)
(B) -1: In-house polymerized product having a molecular weight of 1000, which is a bifunctional acrylate.
(B) -2: In-house polymerized product having a molecular weight of 750, which is a tetrafunctional acrylate.
(B) -3: a trifunctional acrylate, a polymer produced in-house with a molecular weight of 1000.
(B) -4: a tetrafunctional acrylate, a commercial product having a molecular weight of 1000 (product name: Lipoxy PX-390HT, manufactured by Showa Denko KK).
(B) -5: In-house polymerized product having a molecular weight of 2000, which is a tetrafunctional acrylate.
(B) -6: In-house polymerized product having a molecular weight of 5000 and a tetrafunctional acrylate.
(B) -7: In-house polymerized product of 6-functional acrylate and having a molecular weight of 1000.

(3) Photopolymerization initiator (C)
Benzyldimethyl ketal (Ciba Japan, product name Irgacure 651).

(4) Curing agent (D)
A trimethylolpropane adduct of tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., product name Coronate L-45E). The molar ratio of hydroxyl group / isocyanate group in the pressure-sensitive adhesive composition was calculated by the following formula.

An adhesive sheet was bonded to a silicon wafer having a diameter of 8 inches and a thickness of 0.725 mm on which a dummy circuit pattern was formed. Dicing was performed under the following conditions using a dicing apparatus (DISCO, DAD341).
Chip size: 3mm x 3mm
Cut amount to adhesive sheet: 45μm
Dicing blade: DISCO, NBC-ZH205O-27HEEE (outer diameter 55.56 mm, blade width 35 μm, inner diameter 19.05 mm)
Dicing blade rotation speed: 40,000 rpm
Dicing blade feed rate: 80 mm / sec Cutting water temperature: 25 ° C.
Cutting water volume: 1.0L / min

The pressure-sensitive adhesive layer was cured by irradiating ultraviolet rays from the substrate side of the pressure-sensitive adhesive sheet. The UV irradiation condition was 150 mJ / cm ^{2 for} UV irradiation. The pressure-sensitive adhesive sheet was expanded (expansion amount: 8 mm) to widen the chip interval, the chip was pushed up with a needle pin, adsorbed with a vacuum collet, peeled between the pressure-sensitive adhesive sheet and the chip, and the chip was picked up. CAP-300II of Canon Machinery Co., Ltd. (needle pin shape 250 μmR, number of needle pins 4, needle pin push-up height 0.5 mm) was used for the pickup device.

The following evaluation was performed about the produced adhesive sheet and a pick-up process.
(1) Measurement of storage elastic modulus "Storage elastic modulus" was measured as follows.
A UV-irradiated pressure-sensitive adhesive sheet having a length of 20 mm, a width of 3 mm, and a thickness of 0.03 mm was prepared as a test piece. The UV irradiation condition was 150 mJ / cm ² . The storage elastic modulus was measured by frequency dispersion (0.01 to 80 Hz) using a viscoelasticity measuring device (RSAIII, manufactured by TA Instruments), and the storage elastic modulus under the following conditions was used as an index.
Frequency: 1Hz
Distortion: 0.1%
Temperature: 30 ° C

(2) Dicing property 20 dicing lines of the silicon wafer after the pick-up process were confirmed, the degree of whiskers generated during dicing was visually confirmed, and evaluation was performed according to the following criteria.
A (excellent): There were 10 or more dicing lines without a beard.
○ (good): There were 5 to 9 dicing lines without beards.
X (impossible): There were less than 5 dicing lines without whiskers.

(3) Pickup property The number of chips that could be peeled well between the pressure-sensitive adhesive sheet and the chip in the pickup process and could be picked up with the die attach film completely adhered was counted and evaluated according to the following criteria.
◎ (Excellent): More than 95% of chips could be picked up.
○ (good): 80% or more and less than 95% of chips could be picked up.
X (impossible): Less than 80% of chips could be picked up.

(4) Pressure-sensitive adhesive cracking The needle pin push-up location of the pressure-sensitive adhesive sheet after the pickup process was observed with a microscope, the number of locations where the pressure-sensitive adhesive layer was broken was counted, and evaluated according to the following criteria.
A (excellent): Adhesive cracking occurred at a push-up portion of less than 5%.
○ (good): An adhesive crack occurred at a push-up portion of 5% or more and less than 10%.
X (impossible): An adhesive crack occurred at a push-up portion of 10% or more.

(5) Stability over time The pressure-sensitive adhesive sheet was bonded to a silicon wafer, stored for 1 week, and irradiated with 150 mJ / cm ² of ultraviolet light with a high-pressure mercury lamp, and then the pressure-sensitive adhesive sheet was peeled off. The silicon wafer surface after peeling was observed and evaluated according to the following criteria.
A (Excellent): No adhesive remains on the silicon wafer surface.
○ (good): The adhesive remains on the surface of the silicon wafer, and the degree is less than 5% of the pasted area.
X (impossible): When the pressure-sensitive adhesive remains on the surface of the silicon wafer and the degree thereof is 5% or more of the pasting area.

  The evaluation results are shown in Table 1. In Examples 1 to 6, excellent or good evaluation was obtained in any evaluation items of dicing properties, pickup properties, adhesive cracking, and stability over time. On the other hand, in the pressure-sensitive adhesive sheets according to Comparative Examples 1 to 4, occurrence of cracks in the pressure-sensitive adhesive layer was significant.

  According to the pressure-sensitive adhesive sheet according to the present invention, it is possible to suppress cracking of the pressure-sensitive adhesive due to pin push-up at the time of picking up, and it is possible to prevent problems that cause cracks and contamination during mounting due to the broken pressure-sensitive adhesive layer adhering to the semiconductor member. Accordingly, the pressure-sensitive adhesive sheet according to the present invention is suitably used in a method for manufacturing an electronic component in which a chip is picked up after dicing, mounted on a lead frame, and bonded.

DESCRIPTION OF SYMBOLS 1 Adhesive sheet 2 Base film 3 Adhesive layer 4 Silicon wafer or package 41 Chip 5 Ring frame 6 Dicing blade 61 Notch 7 Lead frame

Claims (6)

A pressure-sensitive adhesive sheet comprising a substrate and a photocurable pressure-sensitive adhesive layer formed on one side of the substrate, and the storage elastic modulus after photocuring of the pressure-sensitive adhesive layer measured under the following conditions is 0.5 to 2.0 (× 108Pa) a and, and the value of the storage modulus of the storage modulus / substrate after photocuring of the adhesive layer is Ri 1-3 der, pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer Contains a (meth) acrylic acid ester polymer (A), a bisphenol A type epoxy acrylate (B), a photopolymerization initiator (C), and a curing agent (D), and (B) has 3 to 4 functionalities. acrylate der Ru pressure-sensitive adhesive sheet.
Frequency: 1Hz
Distortion: 0.1%
Temperature: 30 ° C Before molecular weight of millet scan phenol A type epoxy acrylate (B) is 1000 to 2000, in which the curing agent (D) having a trifunctional or more isocyanate groups, hydroxyl group / isocyanate group in the pressure-sensitive adhesive composition The pressure-sensitive adhesive sheet according to claim 1, wherein the molar ratio is 0.6 to 1.2.   The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the (meth) acrylic acid ester polymer (A) has a weight average molecular weight of 700,000 to 1,500,000.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the base material has a storage elastic modulus of 0.5 to 2.0 (x108 Pa).   The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive has a storage elastic modulus after photocuring of 0.5 to 1.5 (× 108 Pa).   A bonding step of bonding an electronic component to the pressure-sensitive adhesive sheet according to any one of claims 1 to 5, a dicing step of dicing the electronic component after the bonding step, a dicing step, and a base material pressure-sensitive adhesive And a pickup step of picking up the electronic component from the pressure-sensitive adhesive layer by irradiating light from the surface side on which the layer is not formed.