JP5089895B2 - The multilayer adhesive sheet, the adhesive sheet for multilayer adhesive sheets, and the manufacturing method of the electronic component using a multilayer adhesive sheet. - Google Patents

Description

The present invention relates to an adhesive, an adhesive sheet using an adhesive, a multilayer adhesive sheet using an adhesive sheet, and an electronic component manufacturing method using the multilayer adhesive sheet.

As a method of manufacturing an electronic component such as an IC, a chip is manufactured using a wafer or an insulating substrate as a base material, the chip is picked up, fixed to a lead frame or the like with an adhesive, and sealed with a resin or the like. How to do is known. The chip is manufactured by forming a circuit pattern on a semiconductor wafer such as silicon, gallium, or arsenic or an insulating substrate to form an electronic component assembly (work), sticking the electronic component assembly to an adhesive sheet, and then fixing it to a ring frame Then, a method of cutting and separating (dicing) into individual chips has been widely performed (see, for example, Non-Patent Document 1).

A method using a dicing adhesive sheet and a multilayer adhesive sheet (die attach film integrated sheet) having a function of an adhesive for fixing a chip to a lead frame or the like has been proposed. The die attach film integrated sheet is a multilayer adhesive sheet in which an adhesive sheet and a die attach film are integrated. By employing the die attach film integrated sheet for the production of electronic components, the adhesive application step can be omitted.

The die attach film-integrated sheet is superior in controlling the thickness and protrusion of the adhesive portion as compared with a method using an adhesive. Die attach film integrated sheets are widely used for manufacturing semiconductor packages such as chip size packages, stack packages, and system-in packages (see Patent Documents 1 to 3, Non-Patent Document 2, etc.).

Among the die attach film integrated sheets, an acrylic pressure-sensitive adhesive was used for the general pressure-sensitive type. When the acrylic pressure-sensitive adhesive is used, the pressure-sensitive adhesive between the die attach film and the pressure sensitive adhesive sheet is too high, and the pressure sensitive adhesive sheet and the die attach film cannot be mechanically peeled off, which may cause a pickup failure.

Along with the high integration of semiconductor components, the chip size has become larger and thinner, increasing the number of cases where it is difficult to pick up chips after dicing. The adhesive strength between the adhesive sheet and the die attach film is required to have a good balance between chip retention during dicing and ease of peeling during pick-up.

Japanese Patent Laid-Open No. 02-248064 Japanese Patent Laid-Open No. 08-053655 JP 2004-186429 A Ozawa et al., “Furukawa Electric Time Report”, No. 106, P31, Furukawa Electric Co., Ltd. Lintec Corporation, "Adhesive Investigation Line 10", [Search on December 21, 2005], Internet <URL: http://www.lintec.co.jp/l_life/l_life_10.html>

The present invention provides an adhesive, an adhesive sheet using an adhesive, a multilayer adhesive sheet using an adhesive sheet, and a method for producing an electronic component using the multilayer adhesive sheet.

The present invention relates to a urethane polymer having a polyol unit and a polyisocyanate unit, an adhesive containing a polyfunctional isocyanate curing agent, an adhesive sheet using an adhesive, a multilayer adhesive sheet using an adhesive sheet, and a multilayer adhesive sheet. It is the manufacturing method of the used electronic component.

The multilayer pressure-sensitive adhesive sheet of the present invention is excellent in chip retainability at the time of dicing, is difficult to come off from the ring frame at the time of dicing, and has an effect that the chip can be easily peeled off at the time of pick-up work.

In the present specification, the monomer unit means a structural unit derived from a monomer. Unless otherwise indicated, parts and% in this specification are based on mass.

The present invention is a pressure-sensitive adhesive containing a urethane polymer having a polyhydric alcohol unit and an isocyanate unit and a polyfunctional isocyanate curing agent.

(Urethane polymer)
The urethane polymer is a polymer having a polyhydric alcohol unit and an isocyanate unit.

(Polyhydric alcohol unit)
A polyhydric alcohol unit means a structural unit derived from a polyhydric alcohol monomer. A polyhydric alcohol monomer will not be specifically limited if it is a compound which has a 2 or more hydroxyl group, Polyhydric alcohol compounds, such as a diol compound, a triol compound, and a polyol oligomer, are mentioned.

The diol compound is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3′-dimethylol heptane, polyoxyethylene Examples include glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, and butylethylpentanediol.

As the polyol oligomer, a polyester polyol oligomer or a polyether polyol oligomer is preferably used. As the urethane polymer, those having a polyether polyol unit are preferably used.

The polyester polyol oligomer is obtained by condensation polymerization of an acid and a glycol compound. The acid is not particularly limited, and examples thereof include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. As the acid component, not only a carboxylic acid but also a derivative such as a carboxylate, an acid anhydride, and an acid halide can be used as a monomer.

A plurality of compounds may be used in combination as the acid and polyhydric alcohol compound used in the polyester polyol oligomer. Similarly, the polyhydric alcohol used in the polyether polyol oligomer may be used in combination with a plurality of compounds.

The polyol oligomer may have a monomer unit derived from glycerin, trimethylolpropane, pentaerythritol and the like. Instead of the glycol component, a glycol-derived alkoxide may be used as a monomer, and lactones such as polycaprolactone, poly (β-methyl-γ-valerolactone), and polyvalerolactone are used as monomers and subjected to ring-opening polymerization. It may be a polyol unit.

The polyether polyol is not particularly limited, and examples thereof include polypropylene glycol and polyethylene adipate. The polyether polyol can be synthesized by polymerizing an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran using a low molecular weight polyol such as propylene glycol, ethylene glycol, glycerin, trimethylolpropane or the like as an initiator.

(Polyisocyanate unit)
A polyisocyanate unit means a structural unit derived from a polyisocyanate monomer. The polyisocyanate monomer is not particularly limited, and examples thereof include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate.

The aromatic polyisocyanate is not particularly limited, and for example, 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2 , 6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4- Diethyl Benzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate and the like.

The aliphatic polyisocyanate is not particularly limited. For example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene. Examples thereof include diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.

The alicyclic polyisocyanate is not particularly limited. For example, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl -2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatomethyl) cyclohexane, and 1,4-bis (isocyanatomethyl) cyclohexane Etc.

Of the polyisocyanates, readily available aromatic polyisocyanates such as 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-triisocyanate Range isocyanate, 2,6-tolylene diisocyanate, and 4,4′-toluidine diisocyanate are preferably used.

(Multifunctional isocyanate curing agent)
The polyfunctional isocyanate curing agent is not particularly limited, and examples thereof include polyisocyanates and trimethylolpropane adducts thereof, burettes reacted with water, and trimers having an isocyanurate ring.

A catalyst can be used in the polymerization reaction of the polyol and the polyisocyanate. The catalyst is not particularly limited, and an amine-based or organometallic compound such as dibutyltin dilaurate can be used.

Examples of the amine catalyst include ethylenediamine, triethylenediamine, triethylamine, ethanolamine, diethanolamine, and tetramethylhexamethylenediamine.

When the adhesive strength of the pressure-sensitive adhesive is high, pick-up failure may occur. When the pressure-sensitive adhesive is excessive, the pressure-sensitive adhesive strength is lowered and the chip holding property is lowered, and at the same time, it is easily peeled off from the ring frame. For these reasons, the ratio of the urethane polymer and the polyfunctional isocyanate curing agent should be adjusted so that the adhesive strength between the die attach film and the adhesive sheet is about 0.05 to 0.9 N / 20 mm. Is preferred.

The compounding ratio of the urethane-based adhesive and the polyfunctional isocyanate curing agent is 0.5 to 20 parts by mass with respect to 100 parts by mass, and preferably 1 to 10 parts by mass. If the amount of the polyfunctional isocyanate curing agent is small, the adhesive strength may be too strong and pickup failure may occur. If the amount is excessive, the adhesive strength may decrease and chip retention may be deteriorated, and at the same time, the adhesive may be easily peeled off from the ring frame.

1-100 micrometers is preferable and, as for the thickness of an adhesive layer, 2-40 micrometers is more preferable. If the pressure-sensitive adhesive layer is thin, the pressure-sensitive adhesive strength decreases, and chip retention during dicing and peeling from the ring frame may occur. If the pressure-sensitive adhesive layer is thick, the adhesive strength is high, and pickup failure may occur.

(Additives, etc.)
Various additives such as a tackifier resin, a softening agent, an anti-aging agent, a filler, and a thermal polymerization inhibitor may be appropriately added to the adhesive.

(Adhesive sheet)
The pressure-sensitive adhesive sheet is produced by applying a pressure-sensitive adhesive on a base film. 30-300 micrometers is preferable and, as for the thickness of a base film, 60-200 micrometers is more preferable.

Various synthetic resins can be used for the base film. Examples of the material for the base film include polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, ethylene-acrylic acid copolymer, and ionomer resin. A mixture of these resins, a copolymer, a multilayer film, and the like can be used for the base film.

It is preferable to use an ionomer resin as a material for the base film. Among ionomer resins, if an ionomer resin obtained by crosslinking a copolymer having an ethylene unit, a methacrylic acid unit, and a (meth) acrylic acid alkyl ester unit with a metal ion such as Na ⁺ , K ⁺ , or Zn ²⁺ is used, cutting The dust suppressing effect is remarkable and is preferably used.

The molding method of the base film is not particularly limited, and examples thereof include calendar, T-die extrusion, inflation, and casting.

In order to prevent the base film from being charged when the die attach film is peeled off, an antistatic treatment may be applied to the die attach film contact surface and / or non-contact of the base film. For the antistatic treatment, an antistatic agent such as 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- Examples thereof include dimethylaminostyrene quaternary chloride and p-diethylaminostyrene quaternary chloride, and dimethylaminoethyl methacrylate quaternary chloride is preferably used.

The method of using the slip agent and the antistatic agent is not particularly limited. For example, the adhesive may be applied to one side of the base film, and the slip agent and / or the antistatic agent may be applied to the back side thereof. Alternatively, an antistatic agent may be kneaded into the resin of the base film to form a sheet.

A die attach film can be laminated on one side of the base film, and the other side can be an embossed surface having an average surface roughness (Ra) of 0.3 to 1.5 μm. By installing the embossed surface on the machine table side of the expanding device, the base film can be easily expanded in the expanding process after dicing.

(Slip agent)
In order to further improve the expandability after dicing, a slipping agent may be applied to the non-contact surface of the base film, or the slipping agent may be kneaded into the base film.

The slip agent is not particularly limited as long as it is a substance that lowers the coefficient of friction between the pressure-sensitive adhesive sheet and the expander. For example, silicone compounds such as silicone resin and (modified) silicone oil, fluororesin, hexagonal boron nitride, carbon black , And molybdenum disulfide. These friction reducing agents may mix a plurality of components. Since electronic parts are manufactured in a clean room, it is preferable to use a silicone compound or a fluororesin. Among silicone compounds, a copolymer having a silicone graft monomer unit is particularly preferably used because it has good compatibility with the antistatic layer and can achieve a balance between antistatic properties and expandability.

In order to improve the peelability between the pressure-sensitive adhesive sheet and the die attach film, the arithmetic average Ra of the die attach film contact surface of the base film is preferably 0.5 μm or more and 1.5 μm or less.

In order to facilitate the peelability of the adhesive sheet and the die attach film, the die attach film contact surface of the base film may be subjected to a mold release treatment. For the release treatment, release agents such as alkyd resin, silicone resin, fluororesin, unsaturated polyester resin, and wax can be used.

(Manufacture of adhesive sheet)
The method of forming the pressure-sensitive adhesive layer on the base film and forming the pressure-sensitive adhesive sheet is not particularly limited. For example, the pressure-sensitive adhesive on the base film with a coater such as a gravure coater, comma coater, bar coater, knife coater, or roll coater. The method of apply | coating directly is mentioned. The adhesive may be printed on the base film by convex plate printing, concave plate printing, flat plate printing, flexographic printing, offset printing, screen printing, or the like. Although the thickness of an adhesive layer is not limited, It is preferable to set it as about 1-100 micrometers by the thickness after drying.

(Die attach film)
The die attach film is an adhesive film formed by forming a pressure-sensitive adhesive or an adhesive into a film shape. The die attach film is commercially available in a state where an adhesive or a pressure-sensitive adhesive is laminated on a peeling film made of a PET resin or the like, and can transfer the adhesive or the pressure-sensitive adhesive to an adherend.

The material of the die attach film may be a commonly used adhesive or adhesive component. Examples of the adhesive include epoxy, polyamide, acrylic, and polyimide. Examples of adhesives include acrylic, vinyl acetate, ethylene / vinyl acetate copolymer, ethylene / acrylate ester copolymer, polyamide, polyethylene, polysulfone, epoxy, polyimide, polyamic acid, and silicone. , Phenolic, rubber-based polymer, fluororubber-based polymer, and fluororesin.

A mixture, a copolymer, and a laminate of these pressure-sensitive adhesive and adhesive components can be used for the die attach film. The die attach film may be mixed with optional additives such as a photopolymerization initiator, an antistatic agent, and a crosslinking accelerator as necessary.

(Multilayer adhesive sheet)
A method for producing a chip with a die attach film using the dicing tape of the present invention is not particularly limited and may be a known method. For example, a dicing tape is bonded to the die attach film, and the die attach film side is set to 80 ° C. Affixed to a silicon wafer heated in step 1 and fixed, and then diced with a dicing blade to form a chip.

(Method for manufacturing electronic parts)
Although the manufacturing method of the electronic component which uses a multilayer film is not specifically limited, For example, the following procedure is mentioned.
(1) Affix and fix the silicon wafer on the multilayer adhesive sheet.
(2) Fix the multilayer adhesive sheet to the ring frame.
(3) The silicon wafer is diced with a dicing blade.
(4) After expanding the multilayer film radially to increase the chip interval, the chip is pushed up with a needle or the like.
(5) The chip is adsorbed with a vacuum collector or air tweezers, peeled between the adhesive sheet and the die attach film, and the chip with the die attach film attached is picked up.
(6) Mount (mount) the chip with die attach film on the lead frame.
(7) Heat the die attach film and heat bond the chip and lead frame.
(8) Mold the chip mounted on the lead frame or circuit board with resin.
In this manufacturing method, a circuit board or the like on which a circuit pattern is formed can be used instead of the lead frame.

The pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and multilayer pressure-sensitive adhesive sheet according to the examples were manufactured according to the following formulation.
Urethane pressure-sensitive adhesive A: a mixture of 100 parts by mass of a urethane polymer reacted with polypropylene glycol and 4,4′-diphenylmethane diisocyanate and 5 parts by mass of a polyfunctional isocyanate curing agent.
Urethane pressure-sensitive adhesive B: a mixture of 100 parts by mass of a urethane polymer reacted with polyethylene adipate and hexamethylene diisocyanate and 5 parts by mass of a polyfunctional isocyanate curing agent.
Acrylic adhesive: A copolymer of butyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate.
Multifunctional isocyanate curing agent: Trimethylolpropane adduct of 2,4-tolylene diisocyanate (Nihon Polyurethane Coronate L-45E).

The pressure-sensitive adhesive was applied onto a PET separator film, coated so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and laminated on a 100 μm base film to obtain a pressure-sensitive adhesive sheet. A 30 μm die attach film was laminated on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet to obtain a pressure-sensitive adhesive sheet.
Ionomer resin: Mainly composed of Zn salt of ethylene-methacrylic acid-methacrylic acid alkyl ester copolymer, MFR value 1.5 g / 10 min (JIS K7210, 210 ° C.), melting point 96 ° C., containing Zn ²⁺ ions, Mitsui・ A commercial product made by DuPont Polychemical.
Die attach film: Mainly polyimide adhesive, 30 μm thick, commercially available.

(Electronic component assembly)
For the manufacture of electronic components, a silicon wafer having a diameter of 6 inches and a thickness of 0.4 mm formed with a dummy circuit pattern was used. The amount of cut into the dicing tape was 30 μm. Dicing was performed with a chip size of 10 mm × 10 mm.

A DAD341 manufactured by DISCO was used as the dicing apparatus. As a dicing blade, NBC-ZH205O-27HEEE made by DISCO was used.
Dicing blade shape: outer diameter 55.56 mm, blade width 35 μm, inner diameter 19.05 mm.
Dicing blade rotation speed: 40,000 rpm
Dicing blade feed speed: 80 mm / sec.
Cutting water temperature: 25 ° C
Cutting water amount: 1.0 L / min.

(Expanding)
After the silicon wafer was diced, expansion was performed using an expanding apparatus: ELECTRONICS HS-1800 manufactured by HUGLE.
Withdrawal amount: 20mm
Pull-down speed: 20 mm / sec Heating condition: 40 ° C. × 1 minute

Die attach film adhesive strength: A dicing tape laminated to a die attach film is pasted on a silicon wafer preheated to 80 ° C, and it is pressure-bonded in one reciprocation of a 2 kg roller, and 180 ° peel after one day of pressure bonding. The adhesive strength was measured under the conditions of a pulling speed of 300 mm / min.

Chip retention: When the semiconductor wafer was diced under the above conditions, the number of chips held on the multilayer adhesive sheet was evaluated.
◎ (excellent): Chip skipping is less than 5%.
○ (Good): Chip skipping is 5% or more and less than 10%.
X (impossible): chip jump is 10% or more

Pickup property: After the semiconductor wafer was diced under the above conditions, the number of chips to which the die attach film was attached was evaluated.
◎ (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.

The multilayer pressure-sensitive adhesive sheet of the present invention is characterized in that it has excellent chip retention during dicing, is unlikely to come off the ring frame during dicing, and can be easily peeled off during pick-up work. The multilayer pressure-sensitive adhesive sheet is suitable for a method of manufacturing an electronic component that is picked up with a die attach film layer attached to the back surface of the chip after dicing, mounted on a lead frame, etc., and cured and bonded by heating or the like.

Claims (4)

A urethane polymer 100 parts by weight with a polyether polyol Unit and aromatic polyisocyanates units, the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive containing 0.5 to 20 parts by weight of the polyfunctional isocyanate curing agent, a die attach film A multi-layer adhesive sheet that is laminated. The pressure-sensitive adhesive sheet for a multilayer pressure-sensitive adhesive sheet according to claim 1. The manufacturing method of the electronic component using the multilayer adhesive sheet of Claim 1. The polyhydric alcohol unit is a polyether polyol unit and the isocyanate unit is an aromatic polyisocyanate unit. 100 parts by mass of a urethane polymer, and 0.5 to 20 parts by mass of a polyfunctional isocyanate curing agent are contained. The adhesive for multilayer adhesive sheets as described in 1 ..