JP7174637B2 - curable film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curable film for forming a warp prevention layer for preventing warpage of a semiconductor package on the back surface of the semiconductor package.

In recent years, mounting technology for semiconductor packages (hereinafter sometimes simply referred to as "packages") has advanced in functionality, and a variety of semiconductor chips (hereinafter sometimes simply referred to as "chips") can be accommodated in the same package. Also proposed is a fan-out package in which a single package is mounted, and a three-dimensional structure in which another package is placed on top of the package. Therefore, the number of terminals has increased dramatically, and along with miniaturization, it has become necessary to fabricate wiring three-dimensionally on the back side of the package. As the functionality of such packages progresses, warpage occurs in the package due to stress caused by the difference in coefficient of thermal expansion between various chips and wiring that is complicatedly formed to three-dimensionally connect them. However, there is a problem that the manufacturing process becomes easy and the yield decreases. In addition, as the performance of electronic devices increases, the amount of heat generated is increasing, and if the package warps due to heat generation, connection failures and other problems may occur, reducing the durability and reliability of electronic devices. It has become to.

Various proposals have been made to provide a warp-preventing layer on the package for the purpose of preventing such warpage of the package. , a large amount of inorganic filler such as a metal oxide having a small coefficient of linear expansion is added (see, for example, Patent Document 1). However, when a large amount of inorganic filler is added to the anti-warp layer, the flexibility of the anti-warping layer is reduced and the anti-warpage layer becomes hard and brittle. Furthermore, when forming a through electrode (via) on the back side of the package, if a large amount of inorganic filler is mixed in the anti-warp layer, the via formation speed will decrease, and the inorganic filler will form scum after via formation. It is also a problem that it remains and causes a decrease in yield. Against this background, there is a demand for a technique for forming a flexible, low-linear-expansion anti-warp layer with a reduced content of inorganic fillers.

JP 2016-53181 A

Accordingly, an object of the present invention is to provide a curable film for forming an anti-warp layer on the back surface of a semiconductor package, which can form a cured product with a low coefficient of linear expansion even if the inorganic filler content is small. Another object of the present invention is to provide a curable film capable of efficiently forming vias and forming an anti-warping layer which is less susceptible to scum after via formation.
Another object of the present invention is to provide a semiconductor package having a warp prevention layer formed on the back surface thereof, the semiconductor package having a low linear expansion warp prevention layer in which vias can be efficiently formed and scum is less likely to occur after via formation. It is to provide a manufacturing method of
Another object of the present invention is to provide a semiconductor package having a warp prevention layer formed on the back surface thereof, the semiconductor package having a low linear expansion warp prevention layer in which vias can be efficiently formed and scum is less likely to occur after via formation. is to provide
Another object of the present invention is to provide an electronic device equipped with a semiconductor package having the anti-warp layer on its back surface.

As a result of intensive studies to solve the above problems, the present inventors have found that a sheet-like porous support made of a material having a low coefficient of thermal expansion is filled with a curable composition, and cured at a specific glass transition temperature. The curable film that forms the product can form a cured product with a low coefficient of linear expansion even if the content of the inorganic filler is small, and is useful as a material for forming a warp prevention layer on the back surface of a semiconductor package. I found out. In addition, a semiconductor package in which a warp prevention layer is formed on the back surface using the curable film can efficiently form vias, and since scum is less likely to occur after via formation, the defect rate is reduced and the yield is improved. I also found that I could. The present invention has been completed based on these findings.

That is, the present invention provides a curable film for forming a warp-preventing layer on the back surface of a semiconductor package for preventing the warp of the semiconductor package, the porous sheet-like film made of a material having a linear thermal expansion coefficient of 20 ppm/K or less. Provided is a curable film having a configuration in which the pores of a support are filled with a curable composition, and the cured product has a glass transition temperature of 100° C. or lower.

In the curable film, a cured product of the curable composition may have a glass transition temperature of 100° C. or lower.

In the curable film, the curable composition is a composition containing a curable compound (A) and a curing agent (B) and/or a curing catalyst (C), wherein (A) is 50% by weight of the total amount % or more is an epoxy compound having an epoxy equivalent of 140 to 3000 g/eq.

In the curable film, the curable composition contains a curable compound (A) and a curing agent (B), with respect to 1 mol of the curable group in (A). It may be contained in a proportion of 0.8 to 1.2 mol of reactive groups with curable groups.

In the curable film, the curable composition contains a curable compound (A) and a curing catalyst (C) in a ratio of 0.1 to 10 parts by weight of (C) with respect to 100 parts by weight of (A). may be contained in

In the curable film, all the curable compounds (A) contained in the curable composition (when the curing agent (B) is also contained, all the curable compounds (A) and all the curing agents (B )) may have a weighted average molecular weight per functional group of 180 to 1000 g/eq.

In the curable film, the cured product of the curable composition has a thermal linear expansion coefficient of 100 ppm/K or more, and the thermal linear expansion coefficient (α ₂ ) may be 20 ppm/K or less.

In the curable film, the sheet-like porous support may have a thickness of 5 to 500 μm.

In the curable film, the sheet-like porous support may be a nonwoven fabric of cellulose fibers.

In the curable film, the curable composition may contain an inorganic filler (E) in an amount of 0 to 10% by weight based on the curable composition (100% by weight).

The curable film may be a curable film for forming an anti-warp layer on the back surface of the fan-out package.

The present invention also provides a method of manufacturing a semiconductor package with a warp prevention layer, comprising the following steps.
Step 1: Affixing the curable film to the back surface of the semiconductor wafer Step 2: Curing the curable film to form an anti-warping layer

In the method for manufacturing a semiconductor package with a warp prevention layer, the semiconductor wafer may be a reconfigured wafer in which a plurality of arranged semiconductor chips are sealed with a sealing material.

The method for manufacturing a semiconductor package with an anti-warp layer may further include the following step 3.
Step 3: Form a wiring layer on the reconstructed wafer

The method for manufacturing a semiconductor package with an anti-warp layer may further include the following step 4.
Step 4: Singulate a semiconductor wafer having a warpage prevention layer formed on the back surface to obtain a semiconductor package.

The present invention also provides a semiconductor package with an anti-warpage layer, which has an anti-warp layer made of the cured product of the curable film on the back surface of the semiconductor package.

In addition, the present invention provides a method of manufacturing an electronic device, comprising the step of mounting the semiconductor package with the anti-warp layer on a substrate by reflow soldering.

The present invention also provides an electronic device comprising the semiconductor package with the anti-warp layer.

Further, the present invention has a structure in which the pores of a sheet-like porous support made of a material having a linear thermal expansion coefficient of 20 ppm/K or less are filled with a curable composition, and the glass transition temperature of the cured product is 100. ° C. or lower for forming a warp-preventing layer for preventing the semiconductor package from warping on the back surface of the semiconductor package.

The curable film of the present invention can form a cured product with a low linear expansion coefficient even if the content of inorganic fillers such as metal oxides is small, and is a material for forming a warp prevention layer on the back surface of a semiconductor package. is useful as In addition, since it is not necessary to add a large amount of inorganic filler, a semiconductor package having an anti-warpage layer formed on the back surface using the curable film of the present invention can efficiently form vias, and scum after via formation. is less likely to occur, the defect rate can be reduced and the yield can be improved. Furthermore, the warp prevention layer can be easily formed by laminating (laminating) the curable film of the present invention on the back surface of the semiconductor package and curing the film. Efficient.
Therefore, an electronic device having a semiconductor package having a warpage prevention layer made of the cured product of the curable film of the present invention on the back surface is excellent in durability and reliability, and can be efficiently manufactured with high yield.

FIG. 1 is a schematic diagram (cross-sectional view) showing an example of a semiconductor package (fan-out package). (a) is a fan-out package without an anti-warp layer, and (b) is a fan-out package with an anti-warp layer formed on the back surface. FIG. 2 is a schematic diagram showing an example of a semiconductor wafer (reconstruction wafer). (a) is a bottom view, and (b) is a cross-sectional view along A-A'. FIG. 3 is a schematic diagram (cross-sectional view) of an example of a method for manufacturing a package with an anti-warpage layer.

The curable film of the present invention is a curable film for forming a warp-preventing layer on the back surface of a semiconductor package for preventing the semiconductor package from warping, and is a sheet-like film made of a material having a linear thermal expansion coefficient of 20 ppm/K or less. The curable film has a configuration in which the pores of a porous support are filled with the following curable composition, and the cured product has a glass transition temperature of 100° C. or less.

[Semiconductor package]
The semiconductor package (hereinafter sometimes referred to as "semiconductor package of the present invention") having a warpage prevention layer formed on the back surface by the curable film of the present invention is not particularly limited, but for example, a wiring layer is used as a basic configuration. A semiconductor package in which a formed semiconductor chip is sealed with a sealing material is exemplified. A fan-out package in which a plurality of semiconductor chips are mounted in the same package is particularly preferable. FIG. 1A shows a schematic diagram (cross-sectional view) of an example of a semiconductor package (fan-out package) that does not have a warp prevention layer. In FIG. 1(a), 10a is a semiconductor package (fan-out package) having no warp prevention layer, 11 is a sealing material, 12 is a semiconductor chip, and 13 is a wiring layer (rewiring layer). In the fan-out package 10a, a plurality of arrayed semiconductor chips 12 are sealed with a sealing material 11, and wiring layers 13 are formed on the unsealed surfaces of the semiconductor chips 12. FIG. The semiconductor package of the present invention may have components other than the semiconductor chip, sealing material, and wiring layer, such as solder balls, through electrodes (vias), sensors, memories, PMICs, communication devices, and antennas.

The fan-out package may be a fan-out wafer level package (FOWLP) or a fan-out panel level package (FOPLP). FOWLP is manufactured by arranging a plurality of semiconductor chips on a wafer with a diameter of about 300 mm, while FOPLP is manufactured by arranging semiconductor chips on a square panel with a side of 300 mm or more, which is larger than the wafer. It is.

The back surface of the semiconductor package means the surface on which wiring layers (electrodes) are formed on the semiconductor chip in the semiconductor package or the surface opposite to the surface on which the wiring layers (electrodes) are formed. "A surface on which a wiring layer is formed" refers to a surface on which a wiring layer has already been formed. A "surface on which a wiring layer is formed" refers to a surface on which a wiring layer is to be formed, although the wiring layer has not yet been formed. FIG. 1B shows a schematic diagram (cross-sectional view) of an example of a semiconductor package (fan-out package) having a warpage prevention layer formed on the back surface. In FIG. 1B, 10b is a semiconductor package (fan-out package) having a warp prevention layer on the back surface, 11 is a sealing material, 12 is a semiconductor chip, 13 is a wiring layer (resale wiring layer), and 14 is a warpage prevention layer. indicates In the fan-out package 10b, a plurality of arrayed semiconductor chips 12 are sealed with a sealing material 11, a wiring layer 13 is formed on the unsealed surface of the semiconductor chips 12, and wiring on the semiconductor chips 12 is formed. A warp prevention layer 14 is formed on the surface (back surface) opposite to the surface on which the layer 13 is formed.

The back surface of the semiconductor package is not particularly limited as long as it is the surface on which the wiring layer is formed on the semiconductor chip or the surface opposite to the surface on which the wiring layer is formed, and the entire back surface may be formed with a sealing material. , the semiconductor chip may be partially exposed. Solder balls, through electrodes (vias), sensors, memories, PMICs, communication devices, antennas, and the like may be formed on the back surface of the semiconductor package.

[Sheet-like porous support]
The sheet-like porous support (hereinafter sometimes abbreviated as "porous support") has a linear thermal expansion coefficient [for example, -20°C to 300°C (preferably -10 to 300°C, particularly preferably 0 to 300° C., most preferably 0 to 250° C.) is 20 ppm/K or less (preferably 10 ppm/K or less, particularly preferably 7 ppm/K or less). Since the curable film of the present invention uses a porous support made of a material having a linear thermal expansion coefficient of 20 ppm/K or less, the cure shrinkage rate and thermal linear expansion coefficient can be suppressed to be small, and warping due to thermal shock can be suppressed. In addition, it is possible to suppress the occurrence of cracks.

Materials having a coefficient of thermal expansion of 20 ppm/K or less include, for example, paper, cellulose, glass fiber, and liquid crystal materials. In the present invention, among others, paper, cellulose, and glass fiber are preferable, and cellulose is particularly preferable because of its light weight and easy availability.

The porosity of the porous support is, for example, 90-10 vol%, preferably 80-30 vol%, particularly preferably 70-30 vol%, most preferably 70-50 vol%. If the porosity is less than the above range, it becomes difficult to impregnate a sufficient amount of the curable composition, and surface smoothness tends to be difficult to obtain. On the other hand, if the porosity exceeds the above range, the reinforcing effect of the porous support cannot be sufficiently obtained, and it tends to be difficult to keep the cure shrinkage and thermal expansion coefficient small.

As used herein, the term "porosity" refers to the volume ratio of voids in the porous support. The porosity of the porous support can be calculated from the following formula by measuring the surface area, thickness and mass of a 10 cm×10 cm sample. Here, Ar is the area (cm ² ) of the porous support, t is the thickness (cm), W is the mass (g) of the porous support, and M is the density of the material of the porous support. The thickness (t) of the porous support is obtained by measuring 10 points at various positions on the porous support using a film thickness meter (PDN-20 manufactured by PEACOK) and adopting the average value.
Porosity (vol%) = {1-W / (M × Ar × t)} × 100

The thickness of the porous support is, for example, 5-500 μm. The lower limit is preferably 10 μm, particularly preferably 15 μm, most preferably 20 μm. Also, the upper limit is preferably 300 μm, more preferably 200 μm, particularly preferably 100 μm, most preferably 75 μm. The thickness of the porous support can be appropriately adjusted within the above range. For example, when the Tg of the cured product of the curable composition alone is rather low, the curing shrinkage rate can be suppressed by making the porous support thinner. be able to. When the cured product of the curable composition alone has a high Tg, the coefficient of linear thermal expansion can be suppressed by increasing the thickness of the porous support. If the thickness of the porous support exceeds the above range, it tends to be difficult to meet the demands for miniaturization and weight reduction of electronic devices. On the other hand, when the thickness is below the above range, it tends to be difficult to obtain sufficient toughness.

[Curable composition]
The curable composition constituting the curable film of the present invention (hereinafter sometimes referred to as "the curable composition of the present invention") is not particularly limited, but for example, a curable compound (A) and a curing agent (B) and/or a curing catalyst (C).

(Curable compound (A))
The curable compound (A) is not particularly limited, but preferably contains at least a compound having an epoxy group (epoxy compound). When the curable compound (A) contains an epoxy compound, it is particularly limited. 500) of the total amount of the curable compound (A) is 50% by weight or more (preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more. The upper limit is 100% by weight. %). Excessive inclusion of a compound having an epoxy equivalent outside the above range is not preferable because the flexibility of the cured product of the curable composition alone is lowered and the crack resistance is lowered.

The epoxy compounds include alicyclic epoxy compounds, aromatic epoxy compounds, aliphatic epoxy compounds, and the like.

<Alicyclic epoxy compound>
The alicyclic epoxy compound includes known or commonly used compounds having one or more alicyclic rings and one or more epoxy groups in the molecule, and the following compounds are preferred.
(1) A compound in which an epoxy group is directly bonded to an alicyclic ring with a single bond (2) A compound having an alicyclic ring and a glycidyl ether group in the molecule (glycidyl ether type epoxy compound)

Examples of (1) compounds in which an epoxy group is directly bonded to an alicyclic ring through a single bond include compounds represented by the following formula (i).

In formula (i), R″ is a group (p-valent organic group) obtained by removing p hydroxyl groups (—OH) from the structural formula of p-valent alcohol, and p and n each represent a natural number. p Examples of the hydric alcohol [R″(OH) _p ] include polyhydric alcohols (such as alcohols having 1 to 15 carbon atoms) such as 2,2-bis(hydroxymethyl)-1-butanol. p is preferably 1-6, and n is preferably 1-30. When p is 2 or more, n in each group within [ ] (inside the outer bracket) may be the same or different. Specific examples of the compound represented by the above formula (i) include a 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol [for example, , trade name “EHPE3150” (manufactured by Daicel Corporation), etc.] and the like.

Examples of (2) compounds having an alicyclic ring and a glycidyl ether group in the molecule include glycidyl ethers of alicyclic alcohols (especially alicyclic polyhydric alcohols). More specifically, for example, 2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane, 2,2-bis[3,5-dimethyl-4-(2,3-epoxypropoxy) Compounds obtained by hydrogenating bisphenol A epoxy compounds such as cyclohexyl]propane (hydrogenated bisphenol A epoxy compounds); bis[o,o-(2,3-epoxypropoxy)cyclohexyl]methane, bis[o , p-(2,3-epoxypropoxy)cyclohexyl]methane, bis[p,p-(2,3-epoxypropoxy)cyclohexyl]methane, bis[3,5-dimethyl-4-(2, Compounds obtained by hydrogenating bisphenol F type epoxy compounds such as 3-epoxypropoxy)cyclohexyl]methane (hydrogenated bisphenol F type epoxy compounds); hydrogenated biphenol type epoxy compounds; hydrogenated phenol novolac type epoxy compounds; hydrogenated cresol Hydrogenated cresol novolak type epoxy compounds of bisphenol A; hydrogenated naphthalene type epoxy compounds; and compounds obtained by hydrogenating epoxy compounds obtained from trisphenolmethane.

<Aromatic epoxy compound>
Examples of the aromatic epoxy compounds include epibis-type glycidyl ether type epoxy resins obtained by a condensation reaction of bisphenols [e.g., bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, etc.] and epihalohydrin; high-molecular-weight epibis-type glycidyl ether-type epoxy resin obtained by subjecting a bis-type glycidyl ether-type epoxy resin to further addition reaction with the above-mentioned bisphenols; a modified epi-bis-type glycidyl ether-type epoxy resin described later; cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, bisphenol S, etc.] and aldehydes [e.g., formaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, salicylaldehyde, etc.] Furthermore, a novolac alkyl type glycidyl ether type epoxy resin obtained by condensation reaction with epihalohydrin; two phenolic skeletons are bonded to the 9-position of the fluorene ring, and the oxygen atom obtained by removing the hydrogen atom from the hydroxy group of these phenolic skeletons. and epoxy compounds to which glycidyl groups are bonded directly or via alkyleneoxy groups.

Examples of the modified epibis-type glycidyl ether-type epoxy resin include compounds represented by the following formula (ii). In the following formulas, R ¹ to R ⁴ are the same or different and represent a hydrogen atom or a hydrocarbon group. k represents an integer of 1 or more. L ¹ represents a low-polarity linking group and L ² represents a flexible skeleton.

The hydrocarbons include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups combined with these groups.

The aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl alkyl groups having about 1 to 20 carbon atoms (preferably 1 to 10, particularly preferably 1 to 3) such as pentyl group, hexyl group, decyl group, dodecyl group; vinyl group, allyl group, 1-butenyl group, etc. alkenyl group having about 2 to 20 carbon atoms (preferably 2 to 10, particularly preferably 2 to 3); ) can be mentioned as an alkynyl group.

The alicyclic hydrocarbon group is preferably a 3- to 10-membered alicyclic hydrocarbon group, such as 3- to 8-membered (preferably 5- to 8-membered) cycloalkyl groups and the like can be mentioned.

The aromatic hydrocarbon group is preferably an aromatic hydrocarbon group having 6 to 14 (preferably 6 to 10) carbon atoms, such as a phenyl group.

Aliphatic hydrocarbon groups (especially alkyl groups) are preferred as R ¹ to R ⁴ .

The above L ¹ represents a low-polarity linking group, and examples thereof include linear or branched alkylene groups having 1 to 3 carbon atoms, such as methylene, methylmethylene, dimethylmethylene and ethylene.

The aforementioned L ² represents a flexible skeleton, such as an oxyalkylene group having 2 to 4 carbon atoms. Specific examples include an oxyethylene group, an oxypropylene group, an oxybutylene group, an oxytetramethylene group, and the like.

Since the modified epibis-type glycidyl ether-type epoxy resin has the above structure, when it is added to the curable composition, an effect of improving the crack resistance can be obtained.

As the modified epibis-type glycidyl ether-type epoxy resin, a compound represented by the following formula (ii-1) can be preferably used. In the present invention, for example, trade name "EPICLON EXA-4850-1000" (epoxy equivalent: 350, manufactured by DIC), trade name "EPICLON EXA-4850-150" (epoxy equivalent: 433, manufactured by DIC), etc. can be used.

<Aliphatic epoxy compound>
Examples of the aliphatic epoxy compounds include glycidyl ethers of q-valent alcohols having no cyclic structure (where q is a natural number); monohydric or polyhydric carboxylic acids [e.g. adipic acid, sebacic acid, maleic acid, itaconic acid, etc.]; epoxidized oils and fats having double bonds such as epoxidized linseed oil, epoxidized soybean oil, and epoxidized castor oil; polyolefins (poly (including alkadienes) epoxidized products, and the like. Examples of alcohols having no q-valent cyclic structure include monohydric alcohols such as methanol, ethanol, 1-propyl alcohol, isopropyl alcohol, and 1-butanol; ethylene glycol, 1,2-propanediol, 1 Dihydric alcohols such as ,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol; trihydric or higher polyhydric alcohols such as glycerin, diglycerin, erythritol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol and sorbitol; The q-valent alcohol may also be polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, or the like.

(Curing agent (B))
The curing agent (B) that constitutes the curable composition of the present invention is a compound that plays a role in curing the epoxy compound.

As the curing agent (B), a curing agent known or commonly used as a curing agent for epoxy resins can be used. Examples thereof include acid anhydrides, dicarboxylic acids, amines, polyamide resins, imidazoles, polymercaptans, phenols, polycarboxylic acids, dicyandiamides, and organic acid hydrazides. In the present invention, it is selected from the group consisting of acid anhydride (b-1), dicarboxylic acid (b-2), amine (b-3), and phenol (b-4) in terms of excellent reliability. is preferred.

The molecular weight per functional group of the curing agent (B) is, for example, 10 to 10000 g/eq (preferably 20 to 8000 g/eq, more preferably 20 to 7000 g/eq, still more preferably 20 to 5000 g/eq, particularly preferably 20 ~2000 g/eq, most preferably 20-1000 g/eq).

Examples of the acid anhydride (b-1) include methyltetrahydrophthalic anhydride (4-methyltetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, etc.), methylhexahydrophthalic anhydride (4-methylhexahydrophthalic anhydride phthalic anhydride, 3-methylhexahydrophthalic anhydride, etc.), dodecenylsuccinic anhydride, methylendomethylenetetrahydrophthalic anhydride, phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylcyclohexenedicarboxylic anhydride pyromellitic anhydride, trimellitic anhydride, benzophenonetetracarboxylic anhydride, nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, 4-(4-methyl-3-pentenyl)tetrahydrophthalic anhydride acid, succinic anhydride, adipic anhydride, sebacic anhydride, dodecanedioic anhydride, methylcyclohexenetetracarboxylic anhydride, vinyl ether-maleic anhydride copolymer, alkylstyrene-maleic anhydride copolymer and the like. Among them, acid anhydrides that are liquid at 25° C. [eg, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenylsuccinic anhydride, methylendomethylenetetrahydrophthalic anhydride, etc.] are preferred from the viewpoint of handling. As the acid anhydride-based curing agent, an anhydride of a saturated monocyclic hydrocarbon dicarboxylic acid (including an anhydride having a substituent such as an alkyl group bonded to the ring) is preferable from the viewpoint of particularly excellent crack resistance.

As the acid anhydride (b-1), for example, commercially available products such as trade name "Likacid MH700F" (manufactured by Shin Nippon Rika Co., Ltd.) and trade name "HN-5500" (manufactured by Hitachi Chemical Co., Ltd.) It can be used preferably.

Examples of the dicarboxylic acid (b-2) include aromatic dicarboxylic acids such as 4,4'-biphenyldicarboxylic acid, 2,2'-biphenyldicarboxylic acid, phthalic acid, isophthalic acid, and terephthalic acid; oxalic acid, malonic acid; Aliphatic dicarboxylic acids such as acids, succinic acid, adipic acid, 1,6-hexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; acid anhydrides and an ester-type dicarboxylic acid obtained by reacting a polyol compound; and the like. Among these, an ester-type dicarboxylic acid obtained by reacting an acid anhydride with a polyol compound is preferable.

As the acid anhydride used for synthesizing the ester-type dicarboxylic acid, an alicyclic acid anhydride is preferable, and 4-methylhexahydrophthalic anhydride and hexahydrophthalic anhydride are particularly preferable.

The polyol compound is preferably a dihydric or trihydric aliphatic alcohol, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, neo dihydric aliphatic alcohols such as pentyl glycol, dimethylolpropane and poly- _C1-5 alkylene glycol (e.g., polyethylene glycol, polypropylene glycol); trihydric aliphatic alcohols such as glycerin and trimethylolpropane; be done.

Among these, dihydric aliphatic alcohols are preferred, and poly-C _1-5 alkylene glycols are more preferred. The weight average molecular weight of the poly-C _1-5 alkylene glycol is, for example, 500-2000, preferably 600-1600.

As the ester-type dicarboxylic acid obtained by reacting an acid anhydride with a polyol compound, a compound represented by the following formula (b-2-1) is preferable.

In formula (b-2-1), R ⁵ and R ⁶ are the same or different and represent an alkyl group having 1 to 5 carbon atoms, preferably a methyl group or an ethyl group. m ¹ and m ² are the same or different and represent an integer of 0 to 4; L is a group (divalent group) obtained by removing two hydroxyl groups from a polyol compound, and among these, a group obtained by removing two hydroxyl groups from polyethylene glycol or polypropylene glycol is preferable.

As the dicarboxylic acid (b-2), for example, commercial products such as the product name "Rikashid HF-08" (manufactured by Shin Nippon Rika Co., Ltd.) can be preferably used.

Examples of the amine (b-3) include aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine and polypropylenetriamine; -amino-3-methyldicyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, N-aminoethylpiperazine, 3,9-bis(3-aminopropyl)-3,4,8,10-tetraoxaspiro [5,5] Alicyclic polyamines such as undecane; m-phenylenediamine, p-phenylenediamine, tolylene-2,4-diamine, tolylene-2,6-diamine, mesitylene-2,4-diamine, 3,5 - mononuclear polyamines such as diethyltolylene-2,4-diamine, 3,5-diethyltolylene-2,6-diamine, biphenylenediamine, 4,4-diaminodiphenylmethane, 2,5-naphthylenediamine, 2, aromatic polyamines such as 6-naphthylenediamine;

Examples of the phenol (b-4) include aralkyl resins such as novolak-type phenol resins, novolak-type cresol resins, p-xylylene-modified phenol resins, p-xylylene/m-xylylene-modified phenol resins, terpene-modified phenol resins, dicyclo Pentadiene-modified phenolic resin, triphenolpropane, and the like can be mentioned.

(Curing catalyst (C))
The curable composition of the present invention may contain a curing catalyst (C) instead of the curing agent (B) described above or together with the curing agent (B) described above. By using the curing catalyst (C), the curing reaction of the epoxy compound can be advanced to obtain a cured product. The curing catalyst (C) is not particularly limited, but for example, one type of cationic catalyst (cationic polymerization initiator) capable of initiating polymerization by generating cationic species by applying ultraviolet irradiation or heat treatment. Or 2 or more types can be used.

Examples of cationic catalysts (photocationic polymerization initiators) that generate cationic species upon irradiation with ultraviolet rays include hexafluoroantimonate salts, pentafluorohydroxyantimonate salts, hexafluorophosphate salts, and hexafluoroarzenate salts. Examples of the cationic catalyst include, for example, trade name "UVACURE 1590" (manufactured by Daicel Cytec Co., Ltd.), trade names "CD-1010", "CD-1011", and "CD-1012" (manufactured by Sartomer, USA), Commercially available products such as "Irgacure 264" (manufactured by Ciba Japan Co., Ltd.) and "CIT-1682" (manufactured by Nippon Soda Co., Ltd.) can be used.

Examples of cationic catalysts (thermal cationic polymerization initiators) that generate cationic species by heat treatment include aryldiazonium salts, aryliodonium salts, arylsulfonium salts, and allene-ion complexes. Examples of the cationic catalyst include, for example, trade names "PP-33", "CP-66", "CP-77" (manufactured by ADEKA Corporation), trade name "FC-509" (manufactured by 3M), Name "UVE1014" (manufactured by G.E.), product names "San-Aid SI-60L", "San-Aid SI-80L", "San-Aid SI-100L", "San-Aid SI-110L", "San-Aid SI-150L" (above , Sanshin Kagaku Kogyo Co., Ltd.), trade name "CG-24-61" (Ciba Japan Co., Ltd.), and other commercially available products can be used. As the cationic catalyst, further, a compound of a chelate compound of a metal such as aluminum or titanium and acetoacetic acid or diketones and a silanol such as triphenylsilanol, or a metal such as aluminum or titanium and acetoacetic acid or diketones A compound of a chelate compound of and a phenol such as bisphenol S can also be used.

(Organic filler (D))
The curable composition of the present invention may further contain one or more organic fillers (D) as long as the effects of the present invention are not impaired. By containing the organic filler (D), the cure shrinkage and the coefficient of linear thermal expansion can be further suppressed, and the effect of suppressing warpage can be improved. In addition, when the curable composition contains the organic filler (D), an effect of suppressing the curable composition filled in the pores of the porous support from flowing out of the pores is also obtained. Furthermore, the organic filler (D) can also be used as a coloring agent for the curable composition.

Examples of the organic filler (D) include cellulose nanofibers, cellulose particles such as cellulose (nano) crystals, PEEK fibers, liquid crystal materials, single-walled or multi-walled carbon nanotubes free of metal oxides, graphene, oxides, and the like. Examples include carbon materials such as graphene, carbon black, fullerene, and nanodiamond, and these can be used alone or in combination of two or more. The organic filler may have any structure such as a solid structure, a hollow structure, and a porous structure. Among these, a carbon material that can also be used as a black colorant is preferred.

The shape of the organic filler (D) is not particularly limited. An irregular shape and the like can be mentioned.

The average particle size of the organic filler (D) is, for example, 5 nm to 100 μm, preferably 50 nm to 50 μm, particularly preferably 100 nm to 30 μm. If the average particle size is less than the above range, the viscosity tends to increase significantly, making handling difficult. On the other hand, if the average particle size exceeds the above range, the crack resistance tends to decrease. In addition, two or more fillers having sizes within the above range may be mixed and used, thereby making it possible to control the viscosity and physical properties. The average particle size of the organic filler (D) is the median size (d50) determined by a laser diffraction/scattering method.

(Inorganic filler (E))
The curable composition of the present invention may further contain one or more inorganic fillers (E) as long as the effects of the present invention are not impaired. However, when a large amount of inorganic filler is added, problems such as generation of scum due to the inorganic filler and time required for via formation tend to occur during via formation. Therefore, the content (blended amount) of the inorganic filler (E) is preferably 10% by weight or less (0 to 10% by weight), and 5% by weight or less (0 to 5% by weight) is more preferred. By setting the content of the inorganic filler (E) to 10% by weight or less, the generation of scum during via formation is suppressed, making it easier to shorten the time required for via formation. Moreover, it is also preferable that the inorganic filler (E) is not substantially contained by not blending the inorganic filler (E).

Examples of the inorganic filler (E) include silica (e.g., natural silica, synthetic silica, etc.), aluminum oxide (e.g., α-alumina, etc.), titanium oxide, zirconium oxide, magnesium oxide, cerium oxide, yttrium oxide, oxide Metal oxides such as calcium, zinc oxide and iron oxide; carbonates such as calcium carbonate and magnesium carbonate; sulfates such as barium sulfate, aluminum sulfate and calcium sulfate; nitriding such as aluminum nitride, silicon nitride, titanium nitride and boron nitride substances; hydroxides such as calcium hydroxide, aluminum hydroxide, magnesium hydroxide; Lastonite, sepiolite, xonolite, zeolite, hydrotalcite, fly ash, dehydrated sludge, glass beads, glass fiber, diatomaceous earth, silica sand, sendust, alnico magnets, various magnetic powders such as ferrite, hydrated gypsum, alum, Antimony trioxide, magnesium oxysulfate, silicon carbide, potassium titanate, calcium silicate, magnesium silicate, aluminum silicate, magnesium phosphate, copper, iron, etc., which may be used alone or in combination of two or more. can be used. The inorganic filler may have any structure such as a solid structure, a hollow structure, and a porous structure. The inorganic filler may be surface-treated with a known surface treatment agent such as organosilicon compounds such as organohalosilanes, organoalkoxysilanes, and organosilazanes.

The shape of the inorganic filler (E) is not particularly limited. An irregular shape and the like can be mentioned.

The inorganic filler (E) has an average particle size of, for example, 5 nm to 100 μm, preferably 50 nm to 50 μm, particularly preferably 100 nm to 30 μm. If the average particle size is less than the above range, the viscosity tends to increase significantly, making handling difficult. On the other hand, if the average particle size exceeds the above range, the crack resistance tends to decrease. In addition, two or more fillers having sizes within the above range may be mixed and used, thereby making it possible to control the viscosity and physical properties. The average particle size of the inorganic filler is the median size (d50) determined by the laser diffraction/scattering method.

(Curing accelerator)
The curable composition of the present invention may contain a curing accelerator together with the curing agent (B). By containing a curing accelerator together with the curing agent (B), the effect of accelerating the curing speed can be obtained. As the curing accelerator, a known or commonly used curing accelerator can be used without particular limitation, but examples thereof include 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) and salts thereof ( phenol salt, octylate, p-toluenesulfonate, formate, tetraphenylborate salt); 1,5-diazabicyclo[4.3.0]nonene-5 (DBN), and salts thereof (such as phenol salt, octylate, p-toluenesulfonate, formate, tetraphenylborate salt); benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, N,N-dimethylcyclohexylamine, etc. tertiary amine; imidazoles such as 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole; phosphoric acid esters, phosphines such as triphenylphosphine (TPP); tetraphenylphosphonium tetra Phosphonium compounds such as phenylborate and tetraphenylphosphonium tetra(p-tolyl)borate; organometallic salts such as tin octylate and zinc octylate; and metal chelates. These can be used individually by 1 type or in combination of 2 or more types.

As the curing accelerator, for example, trade names "U-CAT SA 506", "U-CAT SA 102", "U-CAT 5003", "U-CAT 18X", "U-CAT 12XD)" (above, San-Apro Co., Ltd.), trade names “TPP-K”, “TPP-MK” (manufactured by Hokko Chemical Industry Co., Ltd.), trade names “PX-4ET” (manufactured by Nippon Chemical Industry Co., Ltd.), etc. A commercial item can be used suitably.

The content of the curable compound (A) in the total amount of the curable composition of the present invention is, for example, 30 to 98% by weight. In addition, selected from aromatic epoxy compounds (e.g., epibis-type glycidyl ether-type epoxy resins, high molecular weight epibis-type glycidyl ether-type epoxy resins, and modified epibis-type glycidyl ether-type epoxy resins) in the total amount of the curable composition. compound) is, for example, 30 to 98% by weight. Further, the proportion of epoxy compounds other than aromatic epoxy compounds in the total amount of the curable composition is, for example, 20% by weight or less, preferably 10% by weight or less, particularly preferably 5% by weight or less, and most preferably 1% by weight. It is below.

In the total amount of epoxy compounds contained in the curable composition of the present invention, aromatic epoxy compounds (e.g., epibis-type glycidyl ether-type epoxy resins, high molecular weight epibis-type glycidyl ether-type epoxy resins, and modified epibis-type glycidyl ether-type A compound selected from epoxy resins) accounts for, for example, 60% by weight or more, preferably 70% by weight or more, particularly preferably 80% by weight or more, and most preferably 90% by weight or more. In addition, an upper limit is 100 weight%. Therefore, the proportion of epoxy compounds other than aromatic epoxy compounds in the total amount of epoxy compounds contained in the curable composition is, for example, 40% by weight or less, preferably 30% by weight or less, particularly preferably 20% by weight or less, and most preferably 40% by weight or less. Preferably, it is 10% by weight or less.

The content of the curing agent (B) is such that the reactive group in (B) with respect to 1 mol of the curable group (e.g., epoxy group) contained in the curable composition is, for example, The ratio is 0.8 to 1.2 mol.

If the content of the curing agent (B) is less than the above range, the curing tends to be insufficient and the toughness of the cured product tends to decrease. On the other hand, when the content of the curing agent (B) exceeds the above range, the polarity of the cured product of the curable composition alone increases, making it susceptible to moisture, which may lead to a decrease in reliability.

The proportion of the total content of the curable compound (A) and the curing agent (B) in the total amount of the curable composition of the present invention (excluding the organic filler (D) and the inorganic filler (E)) is, for example, 80% by weight. Above, preferably 90% by weight or more, particularly preferably 95% by weight or more.

Functionality of all curable compounds (A) (all curable compounds (A) and all curing agents (B) when the curing agent (B) is also contained) contained in the curable composition of the present invention The weighted average molecular weight per group (weighted content ratio) (g/eq) is, for example, 180 to 1000, preferably 200 to 700, particularly preferably 200 to 500, most preferably 250 to 450, particularly preferably 300. ~450. In the curable composition of the present invention, the curable compound (A) (when the curing agent (B) is also contained, the curable compound (A) and the curing agent (B)) have a weighted average value within the above range. It is preferable to select and contain in such a manner that a cured product having flexibility and excellent crack resistance can be obtained by having an appropriate distance between cross-linking points. When the weighted average value is below the above range, flexibility tends to decrease and crack resistance tends to decrease. On the other hand, when the weighted average value exceeds the above range, the density of the cured resin tends to be low, making it difficult to obtain sufficient toughness and weather resistance. The molecular weight per functional group of the epoxy compound is the epoxy equivalent. In addition, the molecular weight per functional group of the acid anhydride (b-1) as a curing agent is the acid anhydride group equivalent, the molecular weight per functional group of the dicarboxylic acid (b-2) is the carboxyl group equivalent, and the amine (b The molecular weight per functional group of -3) is the amine equivalent, and the molecular weight per functional group of phenol (b-4) is the hydroxyl equivalent.

The content of the curing catalyst (C) is not particularly limited, but it should be contained in a proportion of, for example, 0.1 to 10 parts by weight with respect to 100 parts by weight of the curable compound (A) contained in the curable composition. is preferable, relative to the total amount (100 parts by weight) of the epoxy compound contained in the curable composition, for example 0.01 to 15 parts by weight, preferably 0.01 to 12 parts by weight, more preferably 0.05 to 10 parts by weight, particularly preferably 0.1 to 10 parts by weight. By using the curing catalyst (C) within the above range, a cured product having excellent heat resistance and weather resistance can be obtained.

The content of the organic filler (D) is, for example, 50 parts by weight or less (e.g., 1 to 50 parts by weight) with respect to 100 parts by weight of the curable compound contained in the curable composition (the total amount when two or more are contained) parts), preferably 45 parts by weight or less, particularly preferably 40 parts by weight or less. When the content of the organic filler (D) is excessive, the Tg of the cured product of the curable composition alone tends to increase, the flexibility tends to decrease, and the crack resistance tends to decrease.

The content of the curing accelerator is not particularly limited. 2 to 3 parts by weight, particularly preferably 0.25 to 2.5 parts by weight.

(other ingredients)
In addition to the above components, the curable composition of the present invention may contain one or more other components as necessary.

The curable composition of the present invention may contain curable compounds other than epoxy compounds, for example, cationic curable compounds such as oxetane compounds, radical curable compounds such as (meth)acrylates and urethane (meth)acrylates. can contain

The curable composition of the present invention further includes, for example, diluents, antifoaming agents, leveling agents, silane coupling agents, surfactants, flame retardants, colorants, plasticizers, antistatic agents, release agents, oxidizing Inhibitors, UV absorbers, light stabilizers, ion adsorbents, phosphors, and the like can be contained.

In addition, when an acid anhydride is used as the curing agent (B), the use of a hydroxyl group-containing compound such as ethylene glycol, diethylene glycol, propylene glycol, glycerin together with the acid anhydride has the effect of accelerating the curing reaction. It is preferable in that it is The content of the hydroxyl group-containing compound is, for example, 0.1 to 15 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of the acid anhydride.

The curable composition of the present invention can be prepared by mixing the above ingredients. For mixing, generally known mixing devices such as a rotation-revolution stirring deaerator, a homogenizer, a planetary mixer, a three-roll mill, and a bead mill can be used. Moreover, each component may be mixed simultaneously and may be mixed one by one.

The glass transition temperature (Tg) of the cured product (not including the porous support) of the curable composition alone of the present invention is not particularly limited, but is preferably 100° C. or less (eg, −60 to 100° C.). . The upper limit of Tg is preferably 50°C, particularly preferably 40°C, most preferably 25°C. The lower limit of Tg is preferably -40°C, more preferably -30°C, still more preferably -20°C, still more preferably -10°C, particularly preferably 0°C, most preferably 5°C, particularly preferably 10°C. There is). By using a curable composition having a cured product Tg of 100° C. or lower, it becomes easier to control the Tg of the cured product of the curable film of the present invention to 100° C. or lower. That is, the Tg of the cured product of the curable film of the present invention tends to correlate with the Tg of the cured product of the curable composition alone. At least in the range of a temperature higher than the glass transition temperature (for example, -10 to 220°C, preferably 0 to 220°C, particularly preferably 10 to 200°C, most preferably 20 to 220°C, particularly preferably 50 to 220°C) At one point, the cured product of the curable composition of the present invention alone (not including the porous support) has a linear thermal expansion coefficient of, for example, 100 ppm/K or more (eg, 100 to 700 ppm/K, preferably 200 to 500 ppm/K , particularly preferably 300 to 500 ppm/K).

[Curable film]
The curable film of the present invention has a core material in which the pores of the porous support are filled with the curable composition, and the glass transition temperature of the cured product is 100° C. or lower. Since the cured product of the curable film used in the present invention has a low glass transition temperature and is soft as described above, it is excellent in crack resistance. In addition, the curable film that forms a soft cured product (especially soft in a high temperature range of 100 ° C. or higher) has a configuration in which the pores of the porous support are filled with the curable composition. Perhaps because the composition cannot push aside the porous support and expand, the coefficient of linear thermal expansion can be suppressed to a small value, and the occurrence of warping can be prevented.

The curable film of the present invention can be prepared, for example, by impregnating the curable composition diluted with a solvent (eg, 2-butanone) into the porous support, followed by drying to remove the solvent, and It can be produced by semi-curing (curing a part of the curable compound) as necessary.

The method of impregnating the curable composition is not particularly limited, and examples thereof include a method of immersing the porous support in the curable composition. The temperature during immersion is, for example, about 25 to 60.degree. The immersion time is, for example, about 30 seconds to 30 minutes. It is preferable that the immersion is performed under a reduced pressure or pressurized environment because the effect of suppressing the remaining foam and promoting the filling of the curable composition can be obtained.

Drying after impregnation and semi-curing conditions are preferably changed as appropriate depending on the type of curing agent used. For example, when an acid anhydride or phenol is used as a curing agent, heating can be performed at a temperature of less than 100° C. (for example, 25° C. or more and less than 100° C.) for about 1 minute to 1 hour. Lower temperatures are preferred when using amines as curing agents. If the heating temperature or heating time exceeds the above range, the curing reaction of the curable composition filled in the porous support proceeds too much, which may make it difficult to use as a warpage prevention layer.

The ratio of the porous support to the total volume of the curable film of the present invention is, for example, 10 to 90 vol%, preferably 20 to 70 vol%, particularly preferably 30 to 70 vol%, most preferably 30 to 50 vol%. That is, the proportion of the curable composition in the total volume of the curable film of the present invention is, for example, 10 to 90 vol%, preferably 30 to 80 vol%, particularly preferably 30 to 70 vol%, most preferably 50 to 70 vol%. be. When the ratio of the porous support exceeds the above range, it becomes difficult to impregnate the support with a sufficient amount of the curable composition, and surface smoothness tends to be difficult to obtain. On the other hand, if the curable composition exceeds the above range, the reinforcing effect of the porous support cannot be sufficiently obtained, and it tends to be difficult to keep the cure shrinkage and thermal expansion coefficient small.

The curable film of the present invention forms a cured product by heat treatment. The heat treatment conditions are not particularly limited, but the heating temperature is preferably 40 to 300°C, more preferably 60 to 250°C. The heating time can be appropriately adjusted according to the heating temperature and is not particularly limited, but is preferably 1 to 10 hours, more preferably 1 to 5 hours. In the above heat treatment, the heating temperature can be constant, or can be changed continuously or stepwise.

As described above, the glass transition temperature (Tg) of the cured product of the curable film of the present invention is 100° C. or less (eg, −60 to 100° C.), preferably 0 to 90° C., more preferably 5 to 80° C. °C, more preferably 10 to 75°C, particularly preferably 10 to 60°C, most preferably 10 to 50°C, even more preferably 10 to 40°C, most preferably 15 to 40°C. When the cured product of the curable film of the present invention has the above Tg, it has appropriate flexibility and can form an anti-warp layer with excellent crack resistance. Incidentally, the glass transition temperature of the cured product is determined by the method described in Examples.

The coefficient of linear thermal expansion α ₂ of the cured product of the curable film of the present invention [the coefficient of thermal expansion in a temperature range above Tg of the cured product, for example, 100 to 300° C.] is not particularly limited, but is, for example, 20 ppm/K or less (for example, −1 to 20 ppm/K), preferably 15 ppm/K or less, more preferably 12 ppm/K or less, still more preferably 10 ppm/K or less. Therefore, the expansion and contraction at a temperature higher than the Tg of the cured product of the curable composition is suppressed, for example, it is possible to suppress the occurrence of warping when mounting a semiconductor package on a substrate by reflow soldering, and the production yield is improved. can be improved.

The thermal expansion coefficient α ₁ of the cured product of the curable film of the present invention [The temperature range below the Tg of the cured product, for example, -20°C to 100°C, preferably -10 to 100°C, and expansion coefficient] is, for example, 55 ppm/K or less (eg, -1 to 55 ppm/K), preferably 50 ppm/K or less, more preferably 45 ppm/K or less, even more preferably 25 ppm/K or less, particularly preferably 20 ppm/K. It is below. Therefore, the expansion and contraction of the cured product of the curable composition is suppressed at a temperature lower than the Tg, for example, the occurrence of warping due to heat generation of electronic devices can be suppressed, and durability and reliability can be improved. .

Although the film thickness of the curable film of the present invention is not particularly limited, it is, for example, 5 to 500 μm. The lower limit is preferably 10 μm, particularly preferably 15 μm, most preferably 20 μm. Also, the upper limit is preferably 400 μm, more preferably 300 μm, particularly preferably 250 μm, and most preferably 200 μm. If the thickness of the curable film of the present invention exceeds the above range, it tends to be difficult to meet the demands for miniaturization and weight reduction of electronic devices. On the other hand, when the thickness is below the above range, it tends to be difficult to obtain sufficient toughness.

The curable film of the present invention may be further laminated with a metal foil, an insulating layer, a heat radiation sheet, an electromagnetic wave shielding film, etc. on at least one surface.

[Semiconductor package with anti-warp layer]
The semiconductor package with an anti-warp layer of the present invention (hereinafter sometimes referred to as "package with an anti-warp layer") comprises a warp-preventing layer (hereinafter, " It has at least one layer of anti-warp layer of the present invention. Since the anti-warping layer of the present invention has a low coefficient of thermal expansion, it prevents warping and cracking caused by stress due to the difference in coefficient of thermal expansion of semiconductor chips, wiring layers (electrodes), sealing materials, etc., which constitute a semiconductor package. can be suppressed. The degree of warpage of a semiconductor package depends on the combination of the semiconductor chip, encapsulant, wiring layer, etc., which constitute the semiconductor package, and the thickness and structure thereof. Therefore, it is preferable that the composition and thickness of the anti-warp layer of the present invention are appropriately adjusted according to the structure of the semiconductor package.

The thickness of the anti-warp layer of the present invention is, for example, 5 to 500 μm. The lower limit is preferably 10 μm, particularly preferably 15 μm, most preferably 20 μm. Also, the upper limit is preferably 400 μm, more preferably 300 μm, particularly preferably 250 μm, and most preferably 200 μm. When the thickness of the anti-warp layer exceeds the above range, it tends to be difficult to meet the demands for miniaturization and weight reduction of electronic devices. On the other hand, when the thickness is below the above range, it tends to be difficult to obtain sufficient toughness.

The anti-warp layer of the present invention may function as a reinforcing material for printed wiring boards, glass films, and the like.

[Method for manufacturing a semiconductor package with an anti-warpage layer]
The package with a warp prevention layer of the present invention is preferably manufactured through the following steps.
Step 1: Affixing the curable film of the present invention to the back surface of a semiconductor wafer Step 2: Curing the curable film to form an anti-warping layer

As the semiconductor wafer in step 1, any known or commonly used semiconductor wafer containing a plurality of semiconductor chips can be used without particular limitation. Reconstruction wafers in which the semiconductor chips are encapsulated with an encapsulant are preferred. FIG. 2 shows a schematic diagram (cross-sectional view) of an example of a semiconductor wafer (reconstructed wafer), where (a) is a bottom view and (b) is a cross-sectional view taken along line A-A'. In FIG. 2, 20 denotes a rebuilt wafer, 11 denotes a sealing material, and 12 denotes a semiconductor chip. In the reconstructed wafer 20 , a plurality of arranged semiconductor chips 12 are sealed with a sealing material 11 .

A reconstructed wafer can be manufactured by a known and commonly used method, for example, by a method including the following steps I to III.
Step I: A temporary fixing tape is attached to a substrate (wafer or panel), and a semiconductor chip is attached to the substrate through the temporary fixing tape. Obtaining the Reconstructed Wafer Stopped Step III: Stripping the Substrate to Obtain the Reconstructed Wafer

In step I, the substrate may be a wafer with a diameter of about 300 mm or a rectangular panel with a side of 300 mm or more.
In the above step II, as a method for sealing the semiconductor chip, for example, a sealing agent (resin) is applied to the semiconductor chip attached on the substrate, or a sheet-like prepreg is attached to the semiconductor chip, followed by heat treatment. It can be done by The heat treatment can be carried out under the same heating conditions as those for obtaining the above-described cured product of the curable film of the present invention.

The semiconductor wafer used in step 1 may be a semiconductor wafer in which the surface opposite to the back surface (front surface) is temporarily fixed to the substrate. As the semiconductor wafer whose front surface is temporarily fixed to the substrate, for example, a reconstructed wafer temporarily fixed to the substrate obtained in the above step II can be used. When a semiconductor wafer whose front surface is temporarily fixed to a substrate is used, the substrate can be peeled off after forming a warp prevention layer on the back surface in step 2 and then performing step III.

In step 1, the method of attaching the curable film of the present invention to the back surface of a semiconductor wafer includes, for example, attaching the curable film of the present invention to the back surface of a semiconductor wafer, and compressing using a substrate for flattening the surface (for example, It can be performed by pressing at 0.1 to 5 MPa.

As a method for curing the curable film in step 2, for example, when the curable composition constituting the curable film contains a photocationic polymerization initiator, it is preferable to apply light irradiation. Further, when the curable composition constituting the curable film contains a curing agent or a thermal cationic polymerization initiator, heat treatment is preferably performed. Curing of the curable film can be performed while compressing (for example, pressing at 0.1 to 5 MPa) using a substrate for flattening the surface or the like.

For the light irradiation, for example, a mercury lamp, a xenon lamp, a carbon arc lamp, a metal halide lamp, sunlight, an electron beam source, a laser light source, an LED light source, etc. are used, and the cumulative irradiation amount is, for example, 500 to 5000 mJ/cm ² . It is preferable to irradiate in a range. UV-LED (wavelength: 350 to 450 nm) is particularly preferable as the light source.
As the heat treatment, for example, the same heating conditions as those for obtaining a cured product of the curable film of the present invention can be used.

When the semiconductor wafer is a reconstructed wafer, the method for manufacturing a semiconductor package with an anti-warpage layer of the present invention preferably further includes the following steps.
Step 3: Form a wiring layer on the reconstructed wafer

A wiring layer (electrode) can be formed by a well-known and commonly used method. Step 3 may be carried out before Step 1, between Steps 1 and 2, or after Step 2, and is not particularly limited. It is preferably done after step 2 to avoid damage.

It is preferable that the method for manufacturing a semiconductor package with an anti-warp layer of the present invention further includes the following steps.
Step 4: Singulate a semiconductor wafer having a warpage prevention layer formed on the back surface to obtain a semiconductor package.

The separation of the semiconductor wafer into individual pieces in step 4 can be performed using a well-known and commonly used cutting device such as a dicing saw. In addition, when the semiconductor wafer is temporarily fixed to the substrate, it is preferable to separate it from the substrate before separating into individual pieces. If there is adhesive residue after separation, the adhesive residue can be removed by cleaning or the like. preferable.
Process 4 is not particularly limited, but it is efficient to perform it after process 2 (when process 3 is performed, process 3).

FIG. 3 shows a schematic diagram (cross-sectional view) of an example of the method for manufacturing a package with a warp prevention layer according to the present invention. In FIG. 3A, a temporary fixing tape 32 is attached to a substrate 31 (wafer or panel), and a semiconductor chip 12 is attached to the substrate 31 via the temporary fixing tape 32 (step I). Next, in FIG. 3B, the semiconductor chip 12 attached to the substrate 31 is sealed with the sealing material 11 to obtain a reconstructed wafer temporarily fixed on the substrate (step II). Next, in FIGS. 3(c) and 3(d), a curable film 33 is attached to the sealing material 11 (back surface) of the reconstructed wafer (step 1), and the curable film 33 is cured to form the warp prevention layer 14. is formed (step 2). The curable film 33 may be attached and cured while being compressed using the substrate 34 for flattening the surface. Next, in FIG. 3(e), the substrate 31 is peeled off to obtain the reconstructed wafer 30 having the warpage prevention layer 14 on the back surface (step III). Finally, in FIG. 3F, a semiconductor package 10b (fan-out package) having a wiring layer 13 on the surface (front surface) opposite to the anti-warp layer 14 and an anti-warp layer 14 on the back surface. is obtained (step 3). The semiconductor package 10b may be further divided into pieces by dicing (step 4).

[Electronics]
An electronic device of the present invention is characterized by comprising the package with a warp prevention layer of the present invention. Since the electronic device of the present invention includes the package with the warp prevention layer of the present invention, it is possible to suppress the occurrence of warpage and cracking due to heat generation of the semiconductor package, so that it is excellent in durability and reliability. The electronic device of the present invention includes, for example, portable electronic devices such as mobile phones, digital cameras, smart phones, tablet terminals, and electronic dictionaries.

The electronic device of the present invention can be manufactured through a step of mounting the warp prevention layer-attached package obtained by the above method on a substrate by reflow soldering (in particular, reflow soldering using lead-free solder). The anti-warping layer of the package with an anti-warping layer of the present invention has an excellent anti-warping effect even in a high-temperature environment (for example, 150 to 250 ° C.) in which reflow soldering (especially reflow soldering using lead-free solder) is performed. can be demonstrated. Therefore, according to the manufacturing method, high-performance electronic devices can be manufactured with excellent workability and high yield.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Preparation Example 1: Preparation of support (preparation of cellulose nonwoven fabric)
A slurry of microfiber Celish KY110N (manufactured by Daicel Co., Ltd.) was diluted to 0.2% by weight, and a No. A wet cellulose nonwoven fabric was obtained by making a 5C filter paper as a filter cloth.
Blotting papers were placed on both sides of the resulting wet cellulose nonwoven fabric and pressed at a pressure of 0.2 MPa for 1 minute. Next, it is pressed at a pressure of 0.2 MPa for 1 minute, and further dried for 120 seconds by applying it to a drum dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) whose surface temperature is set to 100 ° C., cellulose nonwoven fabric (voids of 60 vol %, basis weight of 9.9 g/m ² , thermal linear expansion coefficient of 5 ppm/K, and thickness of 25 μm).

Examples 1-7
(Preparation of curable film)
A curable composition was prepared according to the formulation shown in Table 1.
After immersing the cellulose non-woven fabric obtained in Preparation Example 1 in the curable composition obtained above under reduced pressure, the solvent is removed under reduced pressure and the curable composition is impregnated again to form a curable film ( Proportion of curable composition: 65 vol%) was prepared.
A cured product obtained by curing the obtained curable film under the curing conditions shown in Table 1 was measured for glass transition temperature and thermal linear expansion coefficient by the following methods. Table 1 shows the results.

(Preparation of sealing material)
100 g of bisphenol A glycidyl ether (YD128), 87 g of Rikacid MH-700F, 2 g of ethylene glycol and 0.5 g of curing accelerator (U-CAT 12XD) were added, and a rotation/revolution vacuum mixer (trade name "Awatori Mixer") was added. (manufactured by Thinky Co.) was used to knead for 2 minutes in a vacuum to obtain a sealing material.

(Fabrication of reconstructed wafer)
A PET double-sided adhesive film having the same diameter was pasted on a circular silicon wafer having a diameter of 6 inches, 37 glass substrates cut into 10 mm squares were arranged on the entire surface at intervals of 10 mm, and the sealing material obtained above was placed thereon. After application, the adhesive was cured at 150° C. for 10 minutes while applying pressure to produce a reconstructed wafer (A) temporarily fixed on a silicon wafer (substrate) shown in FIG. 3(b).

(Preparation of Reconstructed Wafer with Warpage Prevention Layer)
The curable film obtained above is attached to the back surface of the reconstructed wafer (A) obtained above (the surface opposite to the temporarily fixed silicon wafer), and cured at 150 ° C. for 2 hours while applying pressure again. to form an anti-warp layer (cured product). The silicon wafer, which had been temporarily fixed via the PET film, was removed to obtain a reconstructed wafer (B) with an anti-warp layer having an anti-warp layer formed on the back surface shown in FIG. 3(e).

Comparative example 1
(Preparation of curable composition)
A curable composition was prepared according to the formulation shown in Table 2.
A cured product obtained by curing the obtained curable composition alone under the curing conditions shown in Table 2 was measured for the glass transition temperature and thermal linear expansion coefficient by the following methods. Table 2 shows the results.

(Preparation of Reconstructed Wafer with Warpage Prevention Layer)
The curable composition obtained above is applied to the back surface of the reconstructed wafer (A) obtained above (the surface opposite to the temporarily fixed silicon wafer), and cured at 150 ° C. for 2 hours, An anti-warp layer (cured product) was formed. The silicon wafer, which had been temporarily fixed via the PET film, was removed to obtain a reconstructed wafer (B) with an anti-warp layer having an anti-warp layer formed on the back surface shown in FIG. 3(e).

Comparative example 2
(Preparation of curable film)
A curable composition was prepared according to the formulation shown in Table 2.
After immersing the glass cloth in the curable composition obtained above under reduced pressure, the solvent is removed under reduced pressure and the curable composition is impregnated again to form a curable film (the proportion of the curable composition : 65 vol%) was produced.
A cured product obtained by curing the obtained curable film under the curing conditions shown in Table 2 was measured for the glass transition temperature and thermal linear expansion coefficient by the following methods. Table 2 shows the results.

(Preparation of Reconstructed Wafer with Warpage Prevention Layer)
The curable film obtained above is attached to the back surface of the reconstructed wafer (A) obtained above (the surface opposite to the temporarily fixed silicon wafer), and cured at 150 ° C. for 2 hours while applying pressure again. to form an anti-warp layer (cured product). The silicon wafer, which had been temporarily fixed via the PET film, was removed to obtain a reconstructed wafer (B) with an anti-warp layer having an anti-warp layer formed on the back surface shown in FIG. 3(e).

Comparative Examples 3 and 4
A warp-preventing layer-attached reconstructed wafer (B) having a warp-preventing layer formed on the back surface was obtained in the same manner as in Comparative Example 1, except that the curable composition having the formulation shown in Table 2 was used.

[evaluation]
The following evaluations were performed on the cured products obtained in the above Examples and Comparative Examples and the restructured wafers (B) with a warp prevention layer.

(Glass transition temperature (Tg), thermal linear expansion coefficient (α ₁ ) in temperature region lower than Tg, thermal linear expansion coefficient (α ₂ ) in temperature region higher than Tg)
The glass transition temperature and thermal linear expansion coefficient of the cured products of the curable films obtained in the above Examples and Comparative Examples (cured products of the curable composition in the case of Comparative Examples 1, 3 and 4) were measured under the following conditions. did. In both cases, the measured values in 2nd-heating were adopted. Tables 1 and 2 show the results.
Test piece size: initial length 10 mm × width 3.5 mm × thickness 0.035 mm
Measuring device: thermomechanical analysis device (Exstar TMA/SS7100, manufactured by Hitachi High-Technologies Corporation)
Measurement mode: Tensile, constant load measurement (40mN)
Measurement atmosphere: Nitrogen Temperature conditions: 1st-heating -60°C to 120°C, 5°C/min
Cooling from 120°C to -60°C, 20°C/min
2nd-heating -60°C to 220°C, 5°C/min

(Warp prevention)
When the warp-preventing layer-attached reconstructed wafers (B) obtained in the above Examples and Comparative Examples were placed on a flat plate, the difference in height from the flat plate between the center portion and the edge portion was defined as "warp." The temperature of the flat plate was controlled at room temperature (20° C.), 100° C., 200° C., or 250° C., and the “warpage” at each temperature was measured. When the value of "warp" is 200 μm or less at all temperatures, the evaluation of the anti-warp effect is "○", when it is 200 to 1000 μm at any temperature, the evaluation of the anti-warp effect is "△", when it exceeds 1000 μm , and the evaluation of the warp prevention effect was "x". Tables 1 and 2 show the results.

(via formation)
An opening of 60 μmφ was formed in the reconstructed wafer (B) with the anti-warpage layer obtained in the above Examples and Comparative Examples with a laser processing machine using a UV-YAG laser. After formation, the state of the via bottom was observed under a microscope to confirm the presence or absence of scum or the like. A case in which no foreign matter such as scum was observed was evaluated as "good", a case in which a small amount of foreign matter was observed was rated as "fair", and a case in which a large amount of foreign matter was observed was rated as "bad". Tables 1 and 2 show the results.

＜硬化剤＞
・リカシッドＭＨ－７００Ｆ：メチルヘキサヒドロ無水フタル酸、酸無水物基当量１６４．５、新日本理化（株）製
・リカシッドＨＦ－０８：脂環族酸無水物とポリアルキレングリコ－ルとのエステル（ジカルボン酸）、カルボキシル基当量６７２．７、新日本理化（株）製
・ＴＤ２０９１：フェノールノボラック、水酸基当量１０４．０、ＤＩＣ社製
・ＴＥＴＡ：トリエチルテトラミン、アミン当量２３．４、三井化学ファイン（株）製
・Ｄ－４００：ポリオキシアルキレンジアミン、アミン当量１０７．０、三井化学ファイン（株）製
＜水酸基含有化合物＞
・ＥＧ：エチレングリコール、和光純薬工業（株）製
＜溶剤＞
・２－ブタノン、和光純薬工業（株）製
＜硬化促進剤＞
・Ｕ－ＣＡＴ １２ＸＤ：特殊アミン型触媒、サンアプロ（株）製
・ＴＰＰ：トリフェニルホスフィン、和光純薬工業（株）製
＜フィラー＞
・シリカフィラー：粒子径３μｍ以下、日本電気硝子（株）製
＜多孔性支持体＞
・ガラスクロス：空隙率：６２vol％、坪量２４ｇ／ｍ²、熱線膨張係数：３ｐｐｍ／ｋ、厚み２５μｍ、商品名「1037」、東洋紡（株）製 <Epoxy compound>
YD-128: bisphenol A type diglycidyl ether (epoxy equivalent 190, viscosity 13600 mPa s / 25 ° C.), epoxy equivalent 188.6, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. Celoxide 2021P: 3,4-epoxycyclohexylmethyl ( 3,4-epoxy)cyclohexanecarboxylate, epoxy equivalent 130, EXA-4850-150 manufactured by Daicel Corporation: modified epibis-type glycidyl ether type epoxy resin, epoxy equivalent: 433, trade name “EPICLON EXA-4850-150” ”, EXA-4850-1000 manufactured by DIC: modified epibis-type glycidyl ether epoxy resin represented by the following formula (ii-1), epoxy equivalent: 350, trade name “EPICLON EXA-4850-1000”, DIC manufactured by the company

<Curing agent>
・ Rikashid MH-700F: Methylhexahydrophthalic anhydride, acid anhydride group equivalent 164.5, manufactured by Shin Nippon Rika Co., Ltd. ・ Rikashid HF-08: Ester of alicyclic acid anhydride and polyalkylene glycol (Dicarboxylic acid), carboxyl group equivalent 672.7, manufactured by Shin Nippon Rika Co., Ltd. TD2091: phenol novolac, hydroxyl equivalent 104.0, manufactured by DIC TETA: triethyltetramine, amine equivalent 23.4, Mitsui Chemicals Fine ( Co., Ltd. D-400: Polyoxyalkylenediamine, amine equivalent 107.0, Mitsui Chemicals Fine Co., Ltd. <hydroxyl-containing compound>
・ EG: ethylene glycol, manufactured by Wako Pure Chemical Industries, Ltd. <solvent>
・ 2-Butanone, manufactured by Wako Pure Chemical Industries, Ltd. <Curing accelerator>
・U-CAT 12XD: Special amine type catalyst, manufactured by San-Apro Co., Ltd. ・TPP: Triphenylphosphine, manufactured by Wako Pure Chemical Industries, Ltd. <Filler>
・ Silica filler: particle size 3 μm or less, manufactured by Nippon Electric Glass Co., Ltd. <Porous support>
・Glass cloth: Porosity: 62 vol%, Basis weight: 24 g/m ² , Thermal expansion coefficient: 3 ppm/k, Thickness: 25 µm, Trade name: "1037", manufactured by Toyobo Co., Ltd.

10a Semiconductor package without warp prevention layer (fan-out package)
10b Semiconductor package with anti-warp layer (fan-out package)
11 sealing material 12 semiconductor chip 13 wiring layer (rewiring layer)
14 warp prevention layer 20 semiconductor wafer (reconstruction wafer)
30 reconstructed wafer with anti-warp layer 31 substrate (wafer or panel)
32 temporary fixing tape 33 curable film 34 surface flattening substrate

Claims (19)

Curable film for forming an anti-warpage layer on the back surface of a semiconductor package to prevent the warp of the semiconductor package by curing after sticking to the back surface of the semiconductor package, the material having a linear thermal expansion coefficient of 20 ppm/K or less. A curable film having a structure in which the pores of a sheet-like porous support are filled with a curable composition, and the glass transition temperature of the cured product is 100° C. or lower. The curable film according to claim 1, wherein the cured product of the curable composition has a glass transition temperature of 100°C or lower. The curable composition is a composition containing a curable compound (A), a curing agent (B) and / or a curing catalyst (C), and 50% by weight or more of the total amount of (A) has an epoxy equivalent 3. The curable film according to claim 1, wherein the composition is 140-3000 g/eq of an epoxy compound. The curable composition reacts the curable compound (A) and the curing agent (B) with 1 mol of the curable group in (A) with the curable group in (A) in (B). 4. The curable film according to claim 3, which contains 0.8 to 1.2 mol of the reactive group. The curable composition contains a curable compound (A) and a curing catalyst (C) in a ratio of 0.1 to 10 parts by weight of (C) with respect to 100 parts by weight of (A). The curable film according to 3 or 4. Per functional group of all curable compounds (A) (all curable compounds (A) and all curing agents (B) when the curing agent (B) is also contained) contained in the curable composition The curable film according to any one of claims 3 to 5, wherein the weighted average molecular weight of is 180 to 1000 g/eq. A cured product of the curable composition has a coefficient of linear thermal expansion of 100 ppm/K or more, and a coefficient of linear thermal expansion (α2) in a temperature range equal to or higher than the glass transition temperature of the cured product of the curable film is 20 ppm/K or less. A curable film according to any one of claims 1 to 6. The curable film according to any one of claims 1 to 7, wherein the sheet-like porous support has a thickness of 5 to 500 µm. The curable film according to any one of claims 1 to 8, wherein the sheet-like porous support is a nonwoven fabric of cellulose fibers. The curable film according to any one of claims 1 to 9, wherein the curable composition contains 0 to 10% by weight of the inorganic filler (E) relative to the curable composition (100% by weight). The curable film according to any one of claims 1 to 10, which is a curable film for forming an anti-warp layer on the back surface of a fan-out package. A method for manufacturing a semiconductor package with an anti-warpage layer having the following steps.
Step 1: Affixing the curable film according to any one of claims 1 to 11 to the back surface of a semiconductor wafer Step 2: Curing the curable film to form an anti-warping layer 13. The method of manufacturing a semiconductor package with an anti-warp layer according to claim 12, wherein said semiconductor wafer is a reconstructed wafer in which a plurality of arranged semiconductor chips are sealed with a sealing material. 14. The method of manufacturing a semiconductor package with an anti-warpage layer according to claim 13, further comprising the following step 3.
Step 3: Form a wiring layer on the reconstructed wafer 15. The method for manufacturing a semiconductor package with a warp prevention layer according to any one of claims 12 to 14, further comprising the following step 4.
Step 4: Singulate a semiconductor wafer having a warpage prevention layer formed on the back surface to obtain a semiconductor package. A semiconductor package with an anti-warp layer, which has an anti-warp layer made of the cured product of the curable film according to any one of claims 1 to 11 on the back surface of the semiconductor package. A method of manufacturing an electronic device, comprising the step of mounting the semiconductor package with a warp prevention layer according to claim 16 on a substrate by reflow soldering. An electronic device comprising the semiconductor package with an anti-warp layer according to claim 16 . A sheet-like porous support made of a material having a linear thermal expansion coefficient of 20 ppm/K or less has a configuration in which the pores are filled with a curable composition, and a cured product having a glass transition temperature of 100 ° C. or less. The film is applied to the back surface of the semiconductor package and then cured to form an anti-warpage layer on the back surface of the semiconductor package to prevent the semiconductor package from warping.

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