JP5485523B2 - Screen printing adhesive - Google Patents

Description

The present invention is an adhesive excellent in screen printability in which no stringing or plate residue is generated during screen printing, no bubbles are present by screen printing, and an adhesive layer having very small surface irregularities can be formed. It relates to the agent.

Applications that perform precise bonding by printing adhesives by screen printing to form fine patterns are expanding. For example, in order to bond a minute semiconductor on a substrate with a complicated pattern, it is preferable to apply a semiconductor adhesive to a desired bonding area on the substrate by screen printing.

Particularly in the field of adhesives for semiconductors, it is necessary to accurately control the shape of the adhesive layer obtained by screen printing. For this reason, screen adhesiveness and shape stability after application are strictly required for the adhesive.

As an adhesive having excellent screen printing properties, for example, Patent Document 1 describes an adhesive for screen printing containing an epoxy compound, a polyimide resin composed of a specific silicone diamine, an acid dianhydride, and a filler. ing. Such an adhesive is excellent in screen printability, and it is said that the adhesive does not protrude when screen printed.
However, the adhesive for screen printing described in Patent Document 1 has a problem that plate separation is bad at the time of screen printing and the coating amount is unstable.

Patent Document 2 describes an adhesive containing polyimide resin, γ-butyrolactone, diethylene glycol dimethyl ether, etc., and screen printing of such an adhesive enables printing without bleeding or sagging. It is described that an effect can be obtained.
However, when the adhesive described in Patent Document 2 is screen-printed, bubbles are generated at the intersections of the mesh and bubbles are present in the adhesive layer, or the thickness of the adhesive layer is uneven and the surface There was a problem that became uneven.
Japanese Patent Laying-Open No. 2005-060417 Japanese Patent Laid-Open No. 1999-100517

The present invention is an adhesive excellent in screen printability in which no stringing or plate residue is generated during screen printing, no bubbles are present by screen printing, and an adhesive layer having very small surface irregularities can be formed. The purpose is to provide an agent.

The present invention includes an epoxy compound, a solid polymer having a functional group that reacts with an epoxy group and having a weight average molecular weight of 10,000 to 50,000, an ester solvent having an SP value of 9.5 to 10.5, And an adhesive for screen printing containing an acid anhydride curing agent.
The present invention is described in detail below.

The adhesive excellent in screen printability of the present invention (hereinafter also simply referred to as “adhesive of the present invention”) contains an epoxy compound, a solid polymer, an ester solvent, and an acid anhydride curing agent.
The epoxy compound is not particularly limited, and examples thereof include bisphenol type epoxy resins such as bisphenol A type, bisphenol F type, bisphenol AD type, and bisphenol S type, novolak type epoxy resins such as phenol novolak type and cresol novolak type, Examples thereof include aromatic epoxy resins such as trisphenol methane triglycidyl ether, naphthalene type epoxy resins, fluorene type epoxy resins, dicyclopentadiene type epoxy resins, and hydrogenated products thereof. Especially, when using the adhesive agent of this invention for an electronic component use, it is preferable to contain the epoxy compound which has a polycyclic hydrocarbon skeleton in a principal chain. When an epoxy compound having a polycyclic hydrocarbon skeleton in the main chain is contained, the resulting cured product is rigid and impedes molecular movement, exhibits excellent mechanical strength and heat resistance, and absorbs water. Therefore, it exhibits excellent moisture resistance.

The epoxy compound having a polycyclic hydrocarbon skeleton in the main chain is not particularly limited. For example, an epoxy compound having a dicyclopentadiene skeleton such as dicyclopentadiene dioxide and a phenol novolac epoxy compound having a dicyclopentadiene skeleton ( Hereinafter, also referred to as “dicyclopentadiene type epoxy compound”), 1-glycidylnaphthalene, 2-glycidylnaphthalene, 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1 , 7-diglycidylnaphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, 1,2,5,6-tetraglycidylnaphthalene and other epoxy compounds having a naphthalene skeleton (hereinafter referred to as “naphthalene type epoxy compound”) , Te La-hydroxy phenyl ethane type epoxy compounds, tetrakis (glycidyloxyphenyl) ethane, 3,4-epoxy-6-methylcyclohexyl-3,4-epoxy-6-methyl cyclohexanecarboxylate Ne - DOO and the like. Among these, a dicyclopentadiene type epoxy compound is preferably used because it has a rigid skeleton and the cured product can exhibit excellent heat resistance. These epoxy compounds having a polycyclic hydrocarbon skeleton in the main chain may be used alone or in combination of two or more.

The molecular weight of the epoxy compound having the polycyclic hydrocarbon skeleton in the main chain is not particularly limited, but the preferable lower limit of the weight average molecular weight is 500, and the preferable upper limit is 1000. When the molecular weight of the epoxy compound having a polycyclic hydrocarbon skeleton in the main chain is less than 500, the mechanical strength, heat resistance, moisture resistance, etc. of the resulting cured product may not be sufficiently improved. Mechanical properties such as drop tests may be lost.
The weight average molecular weight of the epoxy compound can be measured by a gel permeation chromatography (GPC) method.

The solid polymer has a functional group that reacts with an epoxy group. By containing such a solid polymer, the adhesive of the present invention is excellent in the stability of the layer shape of the adhesive layer formed by screen printing.

It does not specifically limit as a solid polymer which has a functional group which reacts with the said epoxy group, For example, resin which has an amino group, a urethane group, an imide group, a hydroxyl group, a carboxyl group, an epoxy group etc. is mentioned. Among these, a polymer having an epoxy group is preferable. When a polymer having an epoxy group is contained, the epoxy group reacts with the epoxy compound and is incorporated into the skeleton of the cured product, so that the obtained cured product can exhibit excellent heat resistance.

The polymer having an epoxy group is not particularly limited as long as it is a polymer having an epoxy group at the terminal and / or side chain (pendant position). Specifically, for example, epoxy group-containing acrylic rubber, epoxy Examples thereof include a group-containing butadiene rubber, a bisphenol type high molecular weight epoxy resin, an epoxy group-containing phenoxy resin, an epoxy group-containing acrylic resin, an epoxy group-containing urethane resin, and an epoxy group-containing polyester resin. Among them, an epoxy group-containing acrylic resin is suitable because a polymer containing a large amount of epoxy groups can be obtained, and the resulting cured product has better mechanical strength and heat resistance. These polymer polymers having an epoxy group may be used alone or in combination of two or more.

The solid polymer has a lower limit of 10,000 and an upper limit of 50,000 for the weight average molecular weight. If the weight average molecular weight of the solid polymer is less than 10,000, the adhesive layer formed by screen printing is inferior in shape stability, and if it exceeds 50,000, stringing tends to occur during screen printing. Printability is poor. The preferable lower limit of the weight average molecular weight of the solid polymer is 20,000, the preferable upper limit is 40,000, and the more preferable upper limit is 30,000.
The weight average molecular weight of the solid polymer can be measured by a gel permeation chromatography (GPC) method.

Although it does not specifically limit as a compounding quantity of the said solid polymer, A preferable minimum is 10 weight part with respect to 100 weight part of said epoxy resins, and a preferable upper limit is 5000 weight part. When the blending amount of the solid polymer is less than 10 parts by weight, the adhesive layer formed by screen printing may be inferior in film forming stability. When it exceeds 5000 parts by weight, the viscosity of the adhesive of the present invention is low. It becomes too high and screen printability may be inferior. The more preferable lower limit of the blending amount of the solid polymer is 20 parts by weight, and the more preferable upper limit is 1000 parts by weight.

The ester solvent has a lower SP value of 9 and an upper limit of 10.5. By using an ester solvent having an SP value in a specific range in combination with the epoxy compound and a solid polymer having a group capable of reacting with the epoxy group, stringing or the like did not occur during screen printing and was formed. No bubbles are generated in the adhesive layer. The preferable lower limit of the SP value is 9.5, and the preferable upper limit is 10.
In the present specification, the SP value means a solubility parameter, and is a value defined as the square root of the intermolecular bond energy (value obtained by subtracting gas energy from latent heat of evaporation) at 25 ° C. . Generally, the closer the SP value is, the higher the hydrophilicity is, and the higher the SP value is, the lower the hydrophilicity is.

Although the reason for this is not clear, it is considered that the SP value is in a specific range, and thus the affinity with the epoxy resin is high.
Further, such an effect is recognized only in the case of an ester solvent. For example, in an ether solvent or an alcohol solvent, even if the SP value is in the above range, stringing or the like may occur during screen printing. Then, bubbles are generated in the formed adhesive layer. This is thought to be because these solvents have a high self-association property and thus have poor compatibility with epoxy compounds and acid anhydrides.

The ester solvent having an SP value of 9 to 10.5 is not particularly limited, but examples thereof include diacetate compounds such as ethylene glycol diacetate and propylene glycol diacetate, ethylene glycol monoacetate, diethylene glycol monoacetate, and ethylene glycol monomethyl. Examples thereof include monoacetate compounds such as ether monoacetate, ethylene glycol monoethyl monoacetate, propylene glycol monoacetate, dipropylene glycol monoacetate, propylene glycol monomethyl monoacetate and propylene glycol monoethyl monoacetate. Among them, an ester solvent having two or more ester skeletons and a glycol skeleton is preferable because the dipole moment is small and the self-association property is small and the solubility is excellent. Specifically, for example, ethylene glycol diacetate, propylene Glycol diacetate, diethylene glycol diacetate, dipropylene glycol diacetate and the like are suitable. Among these, ethylene glycol diacetate or propylene glycol diacetate is more preferable because the temperature at which the solvent is dried can be lowered. These ester solvents having an SP value of 9 to 10.5 may be used alone or in combination of two or more.

Although it does not specifically limit as a compounding quantity of the said ester solvent, It is preferable to mix | blend so that the adhesive agent of this invention may become the viscosity mentioned later.

The acid anhydride curing agent is not particularly limited. For example, polyazeline acid anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, 5-norbornene-2 , 3-dicarboxylic acid anhydride, norbornane-2,3-dicarboxylic acid anhydride, methyl-5-norbornene-2,3-dicarboxylic acid anhydride, methyl-norbornane-2,3-dicarboxylic acid anhydride, cyclohexane-1 , 2,3-tricarboxylic acid-1,2 anhydride, cyclohexane-1,2,4-tricarboxylic acid-1,2 anhydride and other alicyclic acid anhydrides, 3-methylglutaric acid anhydride, etc. 3-alkyl glutaric acid anhydride having an alkyl group having 1 to 8 carbon atoms, which may have no 2-ethyl-3-propyl glutaric acid 2,3-dialkylglutaric anhydride, 2,4-diethylglutaric anhydride, 2,4-dimethylglutaric anhydride, etc. having an alkyl group having 1 to 8 carbon atoms, which may be branched Alkyl-substituted glutaric anhydrides such as 2,4-dialkylglutaric anhydride having a C 1-8 alkyl group which may be branched, such as phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, etc. Aromatic acid anhydrides, trialkyltetrahydrophthalic anhydride, succinic anhydride and the like can be mentioned. Especially, since a softness | flexibility can be provided to hardened | cured material and adhesive reliability can be improved, a succinic anhydride is suitable. These acid anhydride curing agents may be used alone or in combination of two or more.

The blending amount of the acid anhydride curing agent is not particularly limited, but the preferred lower limit is 5 parts by weight with respect to 100 parts by weight of the epoxy compound (when the solid polymer has an epoxy group), A preferred upper limit is 100 parts by weight. If the blending amount of the acid anhydride curing agent is less than 5 parts by weight, sufficient curability may not be obtained, and if it exceeds 100 parts by weight, it will not contribute to further curability and bleed out. It may cause. The more preferable lower limit of the amount of the acid anhydride curing agent is 10 parts by weight, and the more preferable upper limit is 80 parts by weight.

The adhesive of the present invention may contain a curing accelerator for the purpose of adjusting the curing speed and the physical properties of the cured product.
It does not specifically limit as said hardening accelerator, For example, an imidazole series hardening accelerator, a tertiary amine type hardening accelerator, etc. are mentioned. Among these, an imidazole-based curing accelerator is preferable because it is easy to control the reaction system for adjusting the curing speed and the physical properties of the cured product. These hardening accelerators may be used independently and may use 2 or more types together.

The imidazole curing accelerator is not particularly limited, and examples thereof include 1-cyanoethyl-2-phenylimidazole in which the 1-position of imidazole is protected with a cyanoethyl group, and those whose basicity is protected with isocyanuric acid (trade name “2MA- OK ”, manufactured by Shikoku Kasei Kogyo Co., Ltd.).

The blending amount of the curing accelerator is not particularly limited, and a preferred lower limit is 1 part by weight, preferably 100 parts by weight of the epoxy compound (the total when the solid polymer has an epoxy group). The upper limit is 20 parts by weight. If the blending amount of the curing accelerator is less than 1 part by weight, a sufficient curing rate acceleration effect may not be obtained, and if it exceeds 20 parts by weight, it does not contribute to further acceleration of the curing rate. May cause bleed-out. The more preferable lower limit of the blending amount of the curing accelerator is 2 parts by weight, and the more preferable upper limit is 10 parts by weight.

The adhesive of the present invention may contain an inorganic filler for the purpose of reducing water absorption or improving heat resistance.
The inorganic filler is not particularly limited, and examples thereof include silica, glass fiber, alumina fine particles, and carbon black. Of these, spherical silica is preferred. When blending the above inorganic filler, it is preferable to select a surface-treated inorganic filler for the purpose of preventing the adhesive from thickening, and the adherend may be damaged depending on the purpose. It is preferable to select one having a particle size of about 0.1 to 10 μm so as not to occur.

The amount of the inorganic filler is not particularly limited, and the preferred lower limit is 10 parts by weight and the preferred upper limit is 400 parts by weight with respect to 100 parts by weight of the components other than the inorganic filler. When the blending amount of the inorganic filler is less than 10 parts by weight, effects such as a reduction in water absorption may not be obtained, and when it exceeds 400 parts by weight, screen printability may be impaired.

When the adhesive of the present invention is screen-printed, for example, on a polyethylene terephthalate (PET) sheet that has been subjected to a release treatment, so-called repellency may occur in which the obtained adhesive layer does not adhere to the sheet. The adhesive of the present invention may contain a thickener for the purpose of preventing such repelling.
The thickener is not particularly limited, and examples thereof include silica, polyethylene oxide, hydrogenated castor oil, and ethoxycellulose. Of these, silica is preferred. In addition, when using a silica, it is preferable to use an average particle diameter of 0.1-100 nm. If the average particle diameter of silica is less than 0.1 nm, the viscosity may be excessively increased and screen printability may be impaired. If the average particle diameter exceeds 100 nm, precipitation may occur in the adhesive.

Although it does not specifically limit as a viscosity of the adhesive agent of this invention, The preferable minimum of the viscosity measured on 25 degreeC and 0.5 rpm conditions using an E-type viscosity meter is 0.5 Pas, and a preferable upper limit is 50 Pas. If the viscosity of the adhesive of the present invention is less than 0.5 Pas, the adhesive layer formed after printing may spread out. If it exceeds 50 Pas, stringing occurs during screen printing, resulting in poor release. May be. The more preferable lower limit of the viscosity of the adhesive of the present invention is 1 Pas, and the more preferable upper limit is 40 Pas.

The adhesive according to the present invention has a ratio A / B between the viscosity (A) measured at 25 ° C. and 1 rpm using an E-type viscometer and the viscosity (B) measured at 25 ° C. and 10 rpm. The preferred lower limit is 1 and the preferred upper limit is 5. If the A / B value is less than 1, stringing may occur during screen printing. If it exceeds 5, the leveling of the adhesive layer formed after printing may be poor and irregularities may appear on the surface. . The more preferable lower limit of the A / B value is 1.5, and the more preferable upper limit is 4.

The adhesive of the present invention includes, for example, a predetermined amount of the above-mentioned epoxy compound, solid polymer, ester solvent, acid anhydride curing agent, and additives to be blended as necessary, such as a homodisper, a universal mixer, and a Banbury mixer. And can be produced by a method of mixing using a conventionally known mixer such as a kneader.

The adhesive of the present invention can form an adhesive layer that does not cause stringing or plate residue during screen printing, has no air bubbles by screen printing, and has very small surface irregularities. Therefore, the adhesive of the present invention is suitable as an adhesive for electronic components for bonding a semiconductor and a substrate and semiconductors, for example.

Since the adhesive of the present invention is excellent in screen printability and shape stability of the obtained adhesive layer, it is also suitable as an adhesive layer of a die bonding tape. That is, first, the adhesive of the present invention is applied to one surface of an undivided semiconductor wafer by a screen printing method. Thereafter, the adhesive surface is laminated to face the dicing film. Then, the semiconductor wafer is diced. Also, it can be used in a process of forming a pattern on the plate side of the screen to print an adhesive for screen printing on one side of the divided wafer and then laminating the adhesive side facing the dicing film. . The adhesive printed on the semiconductor wafer or the separated chip obtained by this method can be used for bonding between the substrate and the chip, between the chip and the chip, or between the chip and the glass. The adhesive of the present invention is suitable for a method of applying to the entire surface of a semiconductor wafer because an adhesive layer without bubbles is obtained without the stringing of the adhesive, and the formed adhesive layer is not easily uneven. Can be used.

According to the present invention, stringing and plate residue do not occur at the time of screen printing, and there are no bubbles by screen printing, and it is excellent in screen printability that can form an adhesive layer with very small surface irregularities. Adhesive can be provided.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Examples 1-5, Comparative Examples 1-5)
Each material shown in Table 1 and Table 2 was mixed using a homodisper type stirrer to prepare an adhesive.
The following materials were used for each material.

(Epoxy compound)
(1) HP-7200HH (phenol novolac epoxy compound having a dicyclopentadiene skeleton, manufactured by DIC)
(2) EPR-4023 (epoxy-modified nitrile rubber, manufactured by Adeka)

(Solid polymer)
(1) CP-50S (a copolymer of styrene and GMA, Mw = 20000, epoxy equivalent 310, manufactured by NOF Corporation)
(2) CP-50M (Copolymer of MMA and GMA, Mw = 10000, epoxy equivalent 310, manufactured by NOF Corporation)
(3) CP-30 (Copolymer of MMA and GMA, Mw = 9000, epoxy equivalent 530, manufactured by NOF Corporation)
(4) G-1005S (Copolymer of styrene and GMA, Mw = 100000, epoxy equivalent 3300, manufactured by NOF Corporation)

(solvent)
(1) Ethylene glycol diacetate (Wako Pure Chemical Industries, Ltd.)
(2) Propylene glycol diacetate (Wako Pure Chemical Industries, Ltd.)
(3) Diethylene glycol diacetate (Wako Pure Chemical Industries, Ltd.)
(4) Ethylene glycol monoethyl ether (Wako Pure Chemical Industries, Ltd.)
(5) Methyl lactate (Wako Pure Chemical Industries)

(Acid anhydride curing agent)
YH-309 (Methylbutenyltetrahydrophthalic anhydride, manufactured by JER)

(Curing accelerator)
2MA-OK (imidazole compound, manufactured by Shikoku Chemicals)

(Other)
AC-4030 (core shell type rubber particles, manufactured by Ganz Kasei Co., Ltd.)

(Evaluation)
The adhesives obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were evaluated according to the following criteria. The results are shown in Tables 1 and 2.

(Evaluation of screen printability)
Using ST325 mesh with an opening of 100 mm □ (plate size 320 mm □, emulsion thickness 20 μm), when each varnish was screen-printed on a mirror wafer, the presence of stringing and plate residue was visually observed, evaluated. Screen printing was performed under the conditions of a squeegee pressure of 250 MPa, a squeegee speed of 50 mm / sec, and a gap of 1 mm.

(Evaluation of formed adhesive layer)
After the solvent was dried at 80 ° C. for 20 minutes, the presence or absence of bubbles was visually observed and evaluated using a microscope (VHX S-15, manufactured by Keyence Corporation). Further, the surface roughness was measured using an interference microscope (R3300H manufactured by Nikon Corporation).

According to the present invention, stringing and plate residue do not occur at the time of screen printing, and there are no bubbles by screen printing, and it is excellent in screen printability that can form an adhesive layer with very small surface irregularities. Adhesive can be provided.

Claims (4)

An epoxy compound, a solid polymer having a functional group that reacts with an epoxy group and having a weight average molecular weight of 10,000 to 50,000, an ester solvent having an SP value of 9.5 to 10.5, and acid anhydride An adhesive for screen printing, comprising a product curing agent . 2. The screen printing adhesive according to claim 1, wherein the ester solvent is ethylene glycol diacetate or propylene glycol diacetate. The adhesive for screen printing according to claim 1, wherein the viscosity measured using an E-type viscometer at 25 ° C and 0.5 rpm is 0.5 to 50 Pas. The value of the ratio A / B between the viscosity (A) measured at 25 ° C. and 1 rpm using an E-type viscometer and the viscosity (B) measured at 25 ° C. and 10 rpm is 1 to 5. The adhesive for screen printing according to claim 1.