JP2020117672A - Sheet-like prepreg for sealing fan-out package - Google Patents

Abstract

To provide a sheet-like prepreg for sealing a fan-out package that has a low heat ray expansion coefficient and high flexibility in combination, can form a cured material having excellent warpage prevention property and crack resistance, and is difficult to generate foams in a sealing member when preparing a reconstructed wafer, a fan-out package and its production method.SOLUTION: A sheet-like prepreg for sealing a fan-out package of the present invention is characterized by having a through hole and/or a recess part. The through hole and/or recess part is preferably arranged at a position corresponding to a semiconductor chip mounting part of the fan-out package. The fan-out package of the present invention is characterized in that the semiconductor chip is sealed by a cured material of the sheet-like prepreg for sealing the fan-out package.SELECTED DRAWING: None

Description

The present invention relates to a sheet-shaped prepreg for sealing a fan-out package.

A fan-out package (Fan-Out Package) is a re-distribution layer (RDL) after arranging individual semiconductor chips (dies) on another wafer and sealing them to form a reconstructed wafer. It is a manufacturing technology of a semiconductor package including a step of forming.

In particular, fan-out wafer level packaging (FOWLP) has been attracting attention as one of high-density mounting technologies for realizing high functionality and high speed of devices. Since FOWLP can make the package area larger than the chip, (1) Applicability to HBM (High Bandwidth Memory), and more chips can be arranged to connect more connection terminals. (2) Through mold via It is possible, and (3) since different types of chips can be housed in the same package, it has excellent features such as high functionality and cost reduction adapted to IoT (Internet of Things). In addition, the low heat dissipation of the RDL improves the heat dissipation, and the shorter wiring length enables higher speed, which makes it possible to reduce the size of the board. There is.

In addition, fan-out panel level packaging (FOPLP: Fan-out panel level packaging) can be manufactured at a time by making the work size larger than FOWLP. Is done vigorously. However, as the work size increases, warpage of the rebuilt chip substrate becomes a problem. This warpage causes a crack in the chip substrate and a reduction in the accuracy of the redistribution layer, which causes a problem that the defective rate increases.

The cause of the warpage is that the coefficient of linear thermal expansion of the sealing material, which is an organic material, is larger than that of the semiconductor chip, which is an inorganic material. Therefore, there is known a method of suppressing the linear expansion of the entire system by adding an inorganic filler having a small linear expansion coefficient for the purpose of reducing the linear expansion coefficient of the organic material (Patent Document 1). However, when a large amount of the inorganic filler is added, the melt viscosity of the encapsulant is significantly increased and the usability is deteriorated. Therefore, the amount of the inorganic filler added is limited to ensure moldability. Further, the flexibility of the encapsulant is reduced, and the encapsulant becomes hard and brittle, so that the encapsulant becomes vulnerable to heat shock and cracks easily occur. Further, in FOWLP, chips are three-dimensionally compounded and used through through-molded vias, but there are problems such as scum generation due to the inorganic filler during via formation and time required for via formation. In order to solve such a problem, a flexible and low linear expansion material is desired, but in general, there is a trade-off relationship between flexibility and low linear expansion, and addition of an inorganic filler satisfies both properties. Things can be very difficult.

On the other hand, a film (sheet-like prepreg) obtained by impregnating a sheet-like porous support such as a low linear expansion fibrous non-woven fabric with a curable material as a core material is a material having both flexibility of resin and low linear expansion of matrix fiber. It is known (Patent Document 2).

JP 2004-56141 A JP, 2018-65892, A

However, since the prepreg using the fibrous nonwoven fabric as the core material has poor followability to the uneven shape of the surface, bubbles are likely to be generated in the encapsulating material when the reconstructed wafer is produced by encapsulation, and the defective rate is There was a problem of rising.

Therefore, an object of the present invention is to have a low thermal linear expansion coefficient and high flexibility together, to form a cured product having excellent warp prevention and crack resistance, and to form a bubble in the encapsulant when producing a reconstructed wafer. It is intended to provide a sheet-like prepreg for encapsulating a fan-out package that is less likely to occur.
Another object of the present invention is to provide a method for manufacturing a fan-out package, which is excellent in warp prevention and crack resistance and in which air bubbles in the sealing material are suppressed.
Another object of the present invention is to provide a fan-out package which is excellent in warp prevention property and crack resistance and in which generation of bubbles in the sealing material is suppressed.
Still another object of the present invention is to provide a high-performance and durable electronic device including the fan-out package.

The present inventors have conducted extensive studies to solve the above problems, and as a result, by using a sheet-like prepreg having a through hole and/or a recess as a sealant (sealing material) for a fan-out package. It was found that the manufactured fan-out package is excellent in warp prevention and crack resistance, and suppresses the generation of bubbles in the encapsulant. The present invention has been completed based on these findings.

That is, the present invention provides a sheet-like prepreg for sealing a fan-out package, which has a through hole and/or a recess.

In the sheet-shaped prepreg for sealing the fan-out package, it is preferable that the through hole and/or the recess is arranged at a position corresponding to a semiconductor chip mounting portion of the fan-out package.

The coefficient of linear thermal expansion (α2) in the temperature range of the glass transition temperature or higher of the cured product of the sheet-shaped prepreg for sealing the fan-out package is preferably 20 ppm/K or less.

The sheet-shaped prepreg for sealing the fan-out package may have a curable resin layer laminated on at least one surface.

The sheet-shaped prepreg for sealing the fan-out package may be formed by laminating two or more sheet-shaped prepregs.

In the sheet-like prepreg for sealing the fan-out package, the core material of the sheet-like prepreg may be a nonwoven fabric of cellulose fiber.

The present invention also provides a method for manufacturing a fan-out package, which comprises using the sheet-like prepreg for sealing the fan-out package.

Further, the present invention provides a fan-out package, in which a semiconductor chip is sealed with a cured product of the sheet-shaped prepreg for sealing a fan-out package.

The fan-out package may be a fan-out wafer level package or a fan-out panel level package.

The present invention also provides an electronic device including the fan-out package.

The present invention also provides the use of a sheet-like prepreg having through holes and/or recesses as a fan-out package sealant.

The sheet-like prepreg for encapsulating a fan-out package of the present invention has an appropriate flexibility by heat curing, and has a low shrinkage rate or expansion rate due to heat, and exhibits excellent warpage prevention and crack resistance. A cured product can be formed. Furthermore, bubbles are less likely to be generated in the encapsulant when encapsulating with the fan-out package encapsulating sheet-like prepreg of the present invention to produce a reconstructed wafer. Therefore, the sheet-shaped prepreg for sealing a fan-out package of the present invention can be suitably used as a sealing material for a fan-out package such as FOWLP or FOPLP.

FIG. 1 is a schematic view (cross-sectional view) showing an example of a fan-out package. FIG. 2 is a schematic view showing an example of the sheet-shaped prepreg for sealing a fan-out package of the present invention having a through hole. (A) is a top view and (b) is a sectional view taken along line A-A'. FIG. 3 is a schematic view showing an example of a sheet-shaped prepreg for sealing a fan-out package of the present invention having a recess. (A) is a top view, (b) is a bottom view, and (c) is a sectional view taken along line B-B'. FIG. 4 is a schematic view showing an example of a substrate (wafer or panel) on which semiconductor chips are arranged. (A) is a top view and (b) is a sectional view taken along line C-C'. FIG. 5: is a schematic diagram (cross section) which shows an example of the process of sealing the semiconductor chip arrange|positioned on the board|substrate using the conventional sheet-like prepreg (one which does not have a through-hole and a recessed part). FIG. 6 is a schematic view (cross-sectional view) showing an example of a process of sealing the semiconductor chips arranged on the substrate by using the sheet-like prepreg of the present invention having the through holes. FIG. 7 is a schematic view (cross-sectional view) showing an example of a method for manufacturing a fan-out package using the sheet-like prepreg of the present invention.

[Sheet prepreg for fan-out package encapsulation]
The sheet-shaped prepreg for encapsulating a fan-out package of the present invention (hereinafter, may be abbreviated as “sheet-shaped prepreg of the present invention”) is used as a sealing material for a fan-out package, and includes a through hole and And/or has a recess.

[Fan-out package]
The fan-out package of the present invention sealed with the sheet-like prepreg of the present invention is not particularly limited as long as the semiconductor chip is sealed with the cured product of the sheet-like prepreg of the present invention. , A semiconductor chip, a sealing material, and a rewiring layer as a basic structure. FIG. 1 shows a schematic view (cross-sectional view) of an example of the fan-out package of the present invention. In FIG. 1, 10 is a fan-out package, 11 is a sealing material, 12 is a semiconductor chip, and 13 is a rewiring layer (electrode). In the fan-out package 10, a plurality of arranged semiconductor chips 12 are sealed with a sealing material 11, and a rewiring layer 13 is formed on an unsealed surface of the semiconductor chip 12. The fan-out package may have a configuration other than the semiconductor chip, the sealing material, and the rewiring layer, for example, a solder ball, a through electrode (via), a sensor, a memory, a PMIC, a communication device, an antenna and the like.

The entire encapsulating material in the fan-out package may be formed of the sheet-like prepreg of the present invention, or a part of the encapsulating material may be formed of the sheet-like prepreg of the present invention. Good. That is, the sheet-like prepreg of the present invention is used as a sealing agent (sealing material) that constitutes at least a part of the sealing material in the fan-out package.

Further, the fan-out package of the present invention may be a fan-out wafer level package (FOWLP) or a fan-out panel level package (FOPLP). The FOWLP is manufactured by arranging a plurality of semiconductor chips on a wafer having a diameter of about 300 mm, and the FOPLP is manufactured by arranging the semiconductor chips on a rectangular panel having a side of 300 mm or more, which is larger than the wafer. It is something.

[Sheet prepreg]
The sheet-like prepreg of the present invention is not particularly limited, for example, a sheet-like prepreg having a configuration in which the pores of the sheet-like porous support is filled with a curable composition as a core material, the through-hole and / Alternatively, one having a concave portion can be used.

(Sheet-like porous support)
The sheet-shaped porous support (hereinafter, may be abbreviated as “porous support”) is not particularly limited, but for example, a coefficient of linear thermal expansion [for example, −20° C. to 300° C. (preferably −10 to 300). C., particularly preferably 0 to 300.degree. C., most preferably 0 to 250.degree. C.) is 20 ppm/K or less (preferably 10 ppm/K or less, particularly preferably 7 ppm/K or less). .. When a porous support made of a material having a thermal linear expansion coefficient of 20 ppm/K or less is used for the sheet-like prepreg of the present invention, the curing shrinkage rate and the thermal linear expansion coefficient can be suppressed to be small, and the warp due to the application of thermal shock can be suppressed. There is a tendency that cracks can be suppressed as well as suppressed.

Examples of the material having a coefficient of thermal expansion of 20 ppm/K or less include paper, cellulose, glass fiber, liquid crystal material and the like. In the present invention, among these, paper, cellulose and glass fiber are preferable, and cellulose is particularly preferable because it is lightweight and easily available.

The porosity of the porous support is, for example, 90 to 10 vol%, preferably 80 to 30 vol%, particularly preferably 70 to 30 vol%, and most preferably 70 to 50 vol%. When the porosity is below the above range, it becomes difficult to impregnate a sufficient amount of the curable composition, and it tends to be difficult to obtain surface smoothness. On the other hand, when the porosity exceeds the above range, the reinforcing effect by the porous support cannot be sufficiently obtained, and it tends to be difficult to suppress the curing shrinkage rate and the coefficient of linear thermal expansion to be small.

The term "porosity" as used herein 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 measured at 10 points at various positions of the porous support using a film thickness meter (PDN-20 manufactured by PEACOK), and the average value thereof is adopted.
Porosity (vol%)={1-W/(M×Ar×t)}×100

The thickness of the porous support is, for example, 5 to 500 μm. The lower limit is preferably 10 μm, particularly preferably 15 μm, most preferably 20 μm. The upper limit is preferably 300 μm, more preferably 200 μm, particularly preferably 100 μm, and most preferably 75 μm. The thickness of the porous support can be appropriately adjusted within the above range. For example, when the cured product of the curable composition alone has a low Tg, the porous support is thinned to suppress the curing shrinkage rate. 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 small 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 downsizing and weight reduction of electronic devices. On the other hand, when the thickness is less than the above range, it becomes difficult to obtain sufficient toughness, and when it is used as a sealing material for FOWLP, it tends to be difficult to increase the strength by packaging.

(Curable composition)
The curable composition constituting the sheet-like prepreg of the present invention is not particularly limited, and examples thereof include a composition containing a curable compound (A) and a curing agent (B) and/or a curing catalyst (C). To be

(Curable compound (A))
The curable compound (A) is not particularly limited, but a compound containing at least a compound having an epoxy group (epoxy compound) is preferable. When the curable compound (A) contains an epoxy compound, it is not particularly limited, but for example, the epoxy equivalent (g/eq) is 140 to 3000 (preferably 170 to 1000, more preferably 180 to 1000, and particularly preferably 180 to 1000). The epoxy compound of 500) is 50% by weight or more (preferably 70% by weight or more, particularly preferably 80% by weight or more, most preferably 90% by weight or more, based on the total amount of the curable compound (A). 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 decreases and the crack resistance decreases.

The epoxy compound includes an alicyclic epoxy compound, an aromatic epoxy compound, an aliphatic epoxy compound, and the like.

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

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

In the 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. Examples of the valent alcohol [R″(OH) _p ] include polyhydric alcohols such as 2,2-bis(hydroxymethyl)-1-butanol (alcohols having 1 to 15 carbon atoms) and the like. 1-6 are preferable and, as for n, 1-30 are preferable. When p is 2 or more, n in each group in [] (inside the outer square brackets) 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 [eg, , Trade name “EHPE3150” (manufactured by Daicel Corporation, etc.), and the like.

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

<Aromatic epoxy compound>
Examples of the aromatic epoxy compound include epibis type glycidyl ether type epoxy resins obtained by condensation reaction of bisphenols [eg, bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, etc.] and epihalohydrin; High molecular weight epibis type glycidyl ether type epoxy resin obtained by further addition reaction of bis type glycidyl ether type epoxy resin with the above bisphenols; modified epibis type glycidyl ether type epoxy resin described later; phenols [eg phenol, Cresol, xylenol, resorcin, catechol, bisphenol A, bisphenol F, bisphenol S, etc.] and an aldehyde [eg, formaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, salicylaldehyde, etc.] to obtain a polyhydric alcohol, Furthermore, a novolak alkyl type glycidyl ether type epoxy resin obtained by condensation reaction with epihalohydrin; two phenol skeletons bonded to the 9-position of the fluorene ring, and oxygen atoms obtained by removing hydrogen atoms from the hydroxy groups of these phenol skeletons Examples thereof include epoxy compounds in which a glycidyl group is bonded directly or via an alkyleneoxy group.

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

The hydrocarbon includes an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and a group in which these are bonded.

The aliphatic hydrocarbon group is preferably an aliphatic hydrocarbon group having 1 to 20 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group and a t-butyl group. Group, pentyl group, hexyl group, decyl group, dodecyl group, etc., alkyl group having about 1 to 20 carbon atoms (preferably 1 to 10, particularly preferably 1 to 3); vinyl group, allyl group, 1-butenyl group, etc. An alkenyl group having about 2 to 20 (preferably 2 to 10, particularly preferably 2 to 3) carbon atoms; an ethynyl group, a propynyl group, and the like having 2 to 20 carbon atoms (preferably 2 to 10, particularly preferably 2 to 3) ) Alkynyl group and the like.

As the alicyclic hydrocarbon group, a 3- to 10-membered alicyclic hydrocarbon group is preferable, and examples thereof include 3- to 8-membered (preferably, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, etc.). A cycloalkyl group having about 5 to 8 members) and the like can be mentioned.

The aromatic hydrocarbon group is preferably an aromatic hydrocarbon group having 6 to 14 carbon atoms (preferably 6 to 10 carbon atoms), and examples thereof include a phenyl group.

Among them, as R ^{1 to} R ⁴ , an aliphatic hydrocarbon group (in particular, an alkyl group) is preferable.

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

L ² represents a flexible skeleton, and examples thereof include an oxyalkylene group having 2 to 4 carbon atoms. Specific examples thereof include an oxyethylene group, an oxypropylene group, an oxybutylene group and an oxytetramethylene group.

Since the modified epibis type glycidyl ether type epoxy resin has the above-mentioned constitution, when added to the curable composition, an effect of improving 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. Commercially available products can be used.

<Aliphatic epoxy compound>
Examples of the aliphatic epoxy compound include a glycidyl ether of an alcohol (q is a natural number) having no q-valent cyclic structure; a monovalent or polyvalent carboxylic acid [eg, acetic acid, propionic acid, butyric acid, stearic acid, Adipic acid, sebacic acid, maleic acid, itaconic acid, etc.] glycidyl ester; epoxidized linseed oil, epoxidized soybean oil, epoxidized castor oil, and other epoxidized fats and oils having a double bond; (Including alkadienes) and the like. Examples of the alcohol 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 3,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol and polypropylene glycol; Examples thereof include trihydric or higher polyhydric alcohols such as glycerin, diglycerin, erythritol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitol. Further, the q-valent alcohol may be a polyether polyol, a polyester polyol, a polycarbonate polyol, a polyolefin polyol, or the like.

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

As the curing agent (B), known or commonly used curing agents 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, in particular, 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. At least one compound 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, further 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-methylhexahydroanhydride). Phthalic acid, 3-methylhexahydrophthalic anhydride, etc.), dodecenyl succinic anhydride, methylendomethylenetetrahydrophthalic anhydride, phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylcyclohexenedicarboxylic anhydride , Pyromellitic dianhydride, trimellitic dianhydride, benzophenone tetracarboxylic acid anhydride, nadic acid anhydride, methyl nadic acid anhydride, hydrogenated methyl nadic acid anhydride, 4-(4-methyl-3-pentenyl)tetrahydrophthalic anhydride Examples thereof include acids, succinic anhydride, adipic anhydride, sebacic anhydride, dodecanedioic anhydride, methylcyclohexene tetracarboxylic acid anhydride, vinyl ether-maleic anhydride copolymers and alkylstyrene-maleic anhydride copolymers. Among them, an acid anhydride that is liquid at 25° C. [eg, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenylsuccinic anhydride, methylendomethylenetetrahydrophthalic anhydride, etc.] is preferable from the viewpoint of handleability. As the acid anhydride-based curing agent, an anhydride of a saturated monocyclic hydrocarbon dicarboxylic acid (including a ring to which a substituent such as an alkyl group is bonded) is preferable because it is particularly excellent in crack resistance.

As the acid anhydride (b-1), for example, commercially available products such as trade name "Ricacid 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 and malon. Aliphatic dicarboxylic acid such as acid, succinic acid, adipic acid, 1,6-hexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid; acid anhydride And an ester type dicarboxylic acid obtained by reacting with a polyol compound; and the like. Among these, ester-type dicarboxylic acids obtained by reacting an acid anhydride with a polyol compound are preferable.

The acid anhydride used for the synthesis of the ester-type dicarboxylic acid is preferably an alicyclic acid anhydride, of which 4-methylhexahydrophthalic anhydride and hexahydrophthalic anhydride are preferable.

The polyol compound is preferably a dihydric or trihydric aliphatic alcohol, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, neo. Divalent aliphatic alcohols such as pentyl glycol, dimethylolpropane, poly C _1-5 alkylene glycol (eg, polyethylene glycol, polypropylene glycol, etc.); trivalent aliphatic alcohols such as glycerin, trimethylolpropane, etc. To be

Among these, dihydric aliphatic alcohols are preferable, and poly C _1-5 alkylene glycol is particularly preferable. The weight average molecular weight of the poly C _1-5 alkylene glycol is, for example, 500 to 2000, preferably 600 to 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 the 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, and among them, a methyl group or an ethyl group is preferable. m ¹ and m ² are the same or different and each represents an integer of 0 to 4. L is a group obtained by removing two hydroxyl groups from a polyol compound (divalent group), and among them, a group obtained by removing two hydroxyl groups from polyethylene glycol or polypropylene glycol is preferable.

As the dicarboxylic acid (b-2), for example, a commercially available product such as a trade name “Rikacid HF-08” (manufactured by Shin Nippon Rika Co., Ltd.) can be preferably used.

Examples of the amine (b-3) include aliphatic diamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine and polypropylenetriamine; mensendiamine, isophoronediamine, bis(4 -Amino-3-methyldicyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, N-aminoethylpiperazine, 3,9-bis(3-aminopropyl)-3,4,8,10-tetraoxaspiro Alicyclic polyamines such as [5,5]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 and 3,5-diethyltolylene-2,6-diamine, biphenylenediamine, 4,4-diaminodiphenylmethane, 2,5-naphthylenediamine, 2, Examples thereof include aromatic polyamines such as 6-naphthylenediamine.

Examples of the phenol (b-4) include novolac-type phenol resin, novolac-type cresol resin, p-xylylene-modified phenol resin, aralkyl resin such as p-xylylene/m-xylylene-modified phenol resin, terpene-modified phenol resin, and dicyclohexyl. Examples include pentadiene-modified phenol resin, triphenol propane, and the like.

(Curing catalyst (C))
The curable composition may include a curing catalyst (C) instead of or together with the above-mentioned curing agent (B). By using the curing catalyst (C), the curing reaction of the epoxy compound can proceed and a cured product can be obtained. The curing catalyst (C) is not particularly limited, but for example, one kind of cationic catalyst (cationic polymerization initiator) capable of generating a cationic species by subjecting to ultraviolet irradiation or heat treatment to initiate polymerization can be used. Alternatively, two or more kinds can be used.

Examples of the cation catalyst that generates a cationic species upon irradiation with ultraviolet rays include hexafluoroantimonate salt, pentafluorohydroxyantimonate salt, hexafluorophosphate salt, and hexafluoroalzenate salt. As the above-mentioned cation catalyst, for example, trade name "UVACURE1590" (manufactured by Daicel Cytec Co., Ltd.), trade names "CD-1010", "CD-1011", "CD-1012" (above, manufactured by Sartomer USA), Commercially available products such as the product name “Irgacure 264” (manufactured by Ciba Japan Co., Ltd.) and the product name “CIT-1682” (manufactured by Nippon Soda Co., Ltd.) can be used.

Examples of the cation catalyst that generates a cation species by heat treatment include aryldiazonium salts, aryliodonium salts, arylsulfonium salts, and allene-ion complexes. As the above-mentioned cation catalyst, for example, trade names “PP-33”, “CP-66”, “CP-77” (above, manufactured by ADEKA Corporation), trade name “FC-509” (manufactured by 3M), products Name "UVE1014" (manufactured by GE), trade name "Sun-Aid SI-60L", "Sun-Aid SI-80L", "Sun-Aid SI-100L", "Sun-Aid SI-110L", "Sun-Aid SI-150L" (above) Commercial products such as Sanshin Chemical Industry Co., Ltd.) and trade name "CG-24-61" (manufactured by Ciba Japan Co., Ltd.) can be used. As the above-mentioned cation catalyst, further, a compound of a chelate compound of a metal such as aluminum or titanium and acetoacetic acid or a diketone and a silanol such as triphenylsilanol, or a metal such as aluminum or titanium and an acetoacetic acid or a diketone. It is also possible to use a compound of the chelate compound of 1) with a phenol such as bisphenol S.

(Organic filler (D))
The curable composition may further contain one kind or two or more kinds of organic filler (D) within a range not impairing the effects of the present invention. By containing the organic filler (D), the curing shrinkage rate and the coefficient of linear thermal expansion can be further suppressed to be small, and the effect of suppressing warpage can be improved. In addition, when the curable composition contains the organic filler (D), the curable composition filled in the pores of the porous support can be prevented from flowing out of the pores. Furthermore, the organic filler (D) can also be used as a colorant for the curable composition.

Examples of the organic filler (D) include cellulose nanofibers, cellulose-based particles such as cellulose (nano)crystals, PEEK fibers, liquid crystal materials, single-wall or multi-wall carbon nanotubes containing no metal oxide, graphene, and oxide. Examples thereof 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 be used as a black colorant is preferable.

The shape of the organic filler (D) is not particularly limited, but is, for example, spherical (true spherical, substantially true spherical, elliptic spherical, etc.), polyhedral, rod-shaped (cylindrical, prismatic, etc.), flat plate-shaped, scale-shaped, An indefinite shape and the like can be mentioned.

The average particle diameter of the organic filler (D) is, for example, 5 nm to 100 μm, preferably 50 nm to 50 μm, and particularly preferably 100 nm to 30 μm. When the average particle diameter is less than the above range, the viscosity is remarkably increased and handling tends to be difficult. On the other hand, if the average particle size exceeds the above range, the crack resistance tends to decrease. Further, two or more fillers having sizes within the above range may be mixed and used, whereby the viscosity and physical properties can be controlled. The average particle diameter of the organic filler (D) is the median diameter (d50) measured by the laser diffraction/scattering method.

(Inorganic filler (E))
The curable composition may further contain one kind or two or more kinds of inorganic fillers (E) as long as the effects of the present invention are not impaired. However, if a large amount of inorganic filler is mixed, problems such as scum generation and time required for via formation are likely to occur due to the inorganic filler during via formation. Therefore, the content (blending 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 0% by weight) based on the curable composition (100% by weight). 5% by weight) is more preferable. By setting the content of the inorganic filler (E) to 10% by weight or less, scum generation during via formation is suppressed, and the time required for via formation can be shortened easily. 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 (for example, natural silica and synthetic silica), aluminum oxide (for example, α-alumina), titanium oxide, zirconium oxide, magnesium oxide, cerium oxide, yttrium oxide, and 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 Hydroxides such as calcium hydroxide, aluminum hydroxide, magnesium hydroxide; mica, talc, kaolin, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, amesite, bentonite, asbestos, wo Rastonite, sepiolite, zonolite, zeolite, hydrotalcite, fly ash, dehydrated sludge, glass beads, glass fiber, diatomaceous earth, silica sand, sendust, alnico magnet, magnetic powder of various ferrites, hydrated gypsum, alum, Examples thereof include antimony trioxide, magnesium oxysulfate, silicon carbide, potassium titanate, calcium silicate, magnesium silicate, aluminum silicate, magnesium phosphate, copper and iron. 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 an organosilicon compound such as organohalosilane, organoalkoxysilane, or organosilazane.

The shape of the inorganic filler (E) is not particularly limited, and examples thereof include spherical shapes (true spheres, substantially true spheres, elliptical spheres, etc.), polyhedron shapes, rod shapes (cylindrical shapes, prismatic shapes, etc.), flat plate shapes, scaly shapes, An indefinite shape and the like can be mentioned.

The average particle diameter of the inorganic filler (E) is, for example, 5 nm to 100 μm, preferably 50 nm to 50 μm, and particularly preferably 100 nm to 30 μm. When the average particle diameter is less than the above range, the viscosity is remarkably increased and handling tends to be difficult. On the other hand, if the average particle size exceeds the above range, the crack resistance tends to decrease. Further, two or more fillers having sizes within the above range may be mixed and used, whereby the viscosity and physical properties can be controlled. The average particle diameter of the inorganic filler is the median diameter (d50) measured by the laser diffraction/scattering method.

(Curing accelerator)
The curable composition may contain a curing accelerator together with the curing agent (B). By containing the curing accelerator together with the curing agent (B), the effect of accelerating the curing speed can be obtained. As the curing accelerator, known or commonly used curing accelerators can be used and are not particularly limited. For example, 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) and salts thereof ( For example, phenol salt, octylate, p-toluenesulfonate, formate, tetraphenylborate salt); 1,5-diazabicyclo[4.3.0]nonene-5 (DBN), and salts thereof (for example, Phenol salt, octylate, p-toluenesulfonate, formate, tetraphenylborate salt); benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, N,N-dimethylcyclohexylamine, etc. Tertiary amines; 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole and other imidazoles; phosphoric acid esters, triphenylphosphine (TPP) and other phosphines; tetraphenylphosphonium tetra Phosphonium compounds such as phenyl borate and tetraphenylphosphonium tetra(p-tolyl)borate; organometallic salts such as tin octylate and zinc octylate; 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 name “TPP-K”, “TPP-MK” (above, manufactured by Kitako Chemical Co., Ltd.), trade name “PX-4ET” (manufactured by Nippon Kagaku Kogyo Co., Ltd.), etc. Commercially available products can be preferably used.

The content of the curable compound (A) in the total amount of the curable composition is, for example, 30 to 98% by weight. Further, in the total amount of the curable composition, an aromatic epoxy compound (for example, selected from epibis type glycidyl ether type epoxy resin, high molecular weight epibis type glycidyl ether type epoxy resin, and modified epibis type glycidyl ether type epoxy resin. The compound) content is, for example, 30 to 98% by weight. Further, the proportion of the epoxy compound other than the aromatic epoxy compound 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 as follows.

Aromatic epoxy compounds (for example, epibis type glycidyl ether type epoxy resin, high molecular weight epibis type glycidyl ether type epoxy resin, and modified epibis type glycidyl ether type epoxy resin in the total amount of epoxy compounds contained in the curable composition. The ratio of the compound selected from) is, 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. The upper limit is 100% by weight. Therefore, the proportion of the epoxy compound other than the aromatic epoxy compound in the total amount of the 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, It is preferably 10% by weight or less.

The content of the curing agent (B) is, for example, 1 mol of the curable group (for example, epoxy group) contained in the curable composition, and the reactive group with the curable group of the above (A) in (B) 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, and it becomes more susceptible to moisture, which may lead to lower reliability.

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

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

The content of the curing catalyst (C) is not particularly limited, but should be, for example, 0.1 to 10 parts by weight relative to 100 parts by weight of the curable compound (A) contained in the curable composition. Is preferable, for example, 0.01 to 15 parts by weight, preferably 0.01 to 12 parts by weight, and more preferably 0.05 to 10 parts by weight based on the total amount (100 parts by weight) of the epoxy compound contained in the curable composition. 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 (when two or more kinds are contained, the total amount thereof) contained in the curable composition. Parts), preferably 45 parts by weight or less, particularly preferably 40 parts by weight or less. If 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, but is, for example, 3 parts by weight or less (e.g., 0.1 to 3 parts by weight), preferably 0. 0, based on 100 parts by weight of the epoxy compound contained in the curable composition. 2-3 parts by weight, particularly preferably 0.25 to 2.5 parts by weight.

(Other ingredients)
In addition to the above components, the curable composition may contain one or more other components as required.

The curable composition may contain a curable compound other than an epoxy compound, for example, a cation-curable compound such as an oxetane compound or a radical-curable compound such as (meth)acrylate or urethane (meth)acrylate. can do.

The curable composition further includes, for example, a diluent, a defoaming agent, a leveling agent, a silane coupling agent, a surfactant, a flame retardant, a colorant, a plasticizer, an antistatic agent, a release agent, an antioxidant. , An ultraviolet absorber, a light stabilizer, an ion adsorbent, a phosphor and the like.

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 or glycerin together with the acid anhydride has the effect of promoting the curing reaction. It is preferable in that it can be obtained. 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, based on 100 parts by weight of the acid anhydride.

The curable composition can be prepared by mixing the above components. For mixing, a generally known mixing device such as a self-revolving stirring and defoaming device, a homogenizer, a planetary mixer, a three-roll mill, and a beads mill can be used. Moreover, each component may be mixed simultaneously or sequentially.

The glass transition temperature (Tg) of the cured product (not including the porous support) of the curable composition alone is not particularly limited, but is, for example, −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., further preferably −20° C., further preferably −10° C., particularly preferably 0°C, most preferably 5°C, particularly preferably 10°C), and a temperature above the glass transition temperature (for example, -10 to 220°C, preferably 0 to 220°C, particularly preferably 10 to 200°C, The coefficient of linear thermal expansion of the cured product of the curable composition alone (not including the porous support) at least at one point in the range of most preferably 20 to 220° C., particularly preferably 50 to 220° C. is 100 ppm, for example. /K or more (for example, 100 to 700 ppm/K, preferably 200 to 500 ppm/K, particularly preferably 300 to 500 ppm/K).

[Sheet prepreg]
Examples of the sheet-like prepreg of the present invention include those having a structure in which the pores of the porous support are filled with the curable composition as a core material. The cured product of the curable composition used in the present invention has a low glass transition temperature and is soft as described above, and thus has excellent crack resistance. Further, the curable composition that forms the soft (particularly soft in a high temperature region of 100° C. or higher) cured product has a structure in which the pores of the porous support are filled, but the curable composition is porous. Perhaps because the elastic support cannot be pushed away and expanded, the coefficient of linear thermal expansion can be suppressed to a small value, and the occurrence of warpage can be prevented.

The sheet-like prepreg of the present invention is obtained by, for example, impregnating the curable composition diluted with a solvent (for example, 2-butanone) into the porous support, and then drying the solvent to remove the solvent. It can be produced by semi-curing (curing a part of the curable compound) if 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°C. The immersion time is, for example, about 30 seconds to 30 minutes. It is preferable that the dipping is performed under a reduced pressure or a pressurized environment because the effect of suppressing the remaining foaming and promoting the filling of the curable composition can be obtained.

It is preferable that the conditions of the drying after the impregnation and the semi-curing are appropriately changed depending on the kind of the curing agent used. For example, when an acid anhydride or phenol is used as the curing agent, it can be performed by heating 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. When using an amine as the curing agent, it is preferable to carry out at a lower temperature. If the heating temperature or the 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 sealing material.

The proportion of the porous support in the total volume of the sheet-like prepreg of the present invention is, for example, 10 to 90 vol%, preferably 20 to 70 vol%, particularly preferably 30 to 70 vol%, and most preferably 30 to 50 vol%. That is, the proportion of the curable composition in the total volume of the sheet-like prepreg of the present invention is, for example, 10 to 90 vol%, preferably 30 to 80 vol%, particularly preferably 30 to 70 vol%, and most preferably 50 to 70 vol%. is there. If the proportion of the porous support exceeds the above range, it becomes difficult to impregnate a sufficient amount of the curable composition, and it becomes difficult to obtain surface smoothness. On the other hand, when 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 suppress the curing shrinkage rate and the coefficient of linear thermal expansion to be small.

The sheet-like prepreg of the present invention forms a cured product by being subjected to heat treatment. The heat treatment condition is 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 may be constant or may be changed continuously or stepwise.

The glass transition temperature (Tg) of the cured product of the sheet-like prepreg of the present invention is not particularly limited, but is, for example, −60° C. or higher and 100° C. or lower (−60 to 100° C.), preferably 0 to 90° C., The temperature is more preferably 5 to 80°C, still more preferably 10 to 75°C, particularly preferably 10 to 60°C, most preferably 10 to 50°C, further preferably 10 to 40°C, and particularly preferably 15 to 40°C. When the cured product of the sheet-like prepreg of the present invention has the above Tg, it has appropriate flexibility and is excellent in crack resistance. The glass transition temperature of the cured product is determined by the method described in the examples.

The thermal linear expansion coefficient α ₂ of the cured product of the sheet-like prepreg of the present invention [the thermal linear expansion coefficient in the temperature region of Tg or higher 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, expansion and contraction of the cured product of the curable composition at a temperature higher than Tg are suppressed, and for example, warpage can be suppressed when the fan-out package is mounted on the substrate by reflow soldering, and the manufacturing yield can be improved. Can be improved.

Thermal linear expansion coefficient α ₁ of the cured product of the sheet-like prepreg of the present invention [heat ray in the temperature region of Tg or lower of the cured product, for example, −20° C. to 100° C., preferably −10 to 100° C., particularly preferably 0 to 100° C. Expansion coefficient] is, for example, 55 ppm/K or less (for example, −1 to 55 ppm/K), preferably 50 ppm/K or less, more preferably 45 ppm/K or less, further preferably 25 ppm/K or less, particularly preferably 20 ppm/K. It is as follows. Therefore, expansion and contraction of the cured product of the curable composition at a temperature lower than Tg are suppressed, and, for example, generation of warpage due to heat generation of electronic devices can be suppressed, and durability and reliability can be improved. ..

The sheet-like prepreg of the present invention can also be suitably used as a sealing material for compression molding.

[Through hole, recess]
The sheet-like prepreg of the present invention has a through hole and/or a recess. Since the sheet-like prepreg of the present invention has through holes and/or recesses, it is a sealing material when sealing semiconductor chips arranged on a wafer or panel (hereinafter, may be collectively referred to as “substrate”). Bubbles are less likely to be generated inside, and the effect of reducing the defective rate (improving the yield) is achieved. Hereinafter, description will be given with reference to the drawings.

2A and 2B are schematic views showing an example of the sheet-like prepreg of the present invention having through holes, in which FIG. 2A is a top view and FIG. 2B is a sectional view taken along line AA′. In FIG. 2, 20 is a sheet-like prepreg having a through hole, and 21 is a through hole. The sheet-like prepreg 20 has a plurality of through holes 21.
3A and 3B are schematic views showing an example of the sheet-like prepreg of the present invention having a concave portion, FIG. 3A is a top view, FIG. 3B is a bottom view, and FIG. 3C is a sectional view taken along line BB′. In FIG. 3, 30 is a sheet-like prepreg having a recess, and 31 is a recess. The sheet-like prepreg 30 has a plurality of recesses 31.

The sheet-like prepreg of the present invention may have only through holes, only recesses, or both through holes and recesses. The number of through holes and/or recesses (total number of through holes and recesses) included in the sheet-like prepreg of the present invention is not particularly limited, but generally 1 to 6 per unit depending on the design of the fan-out package to be manufactured. It can be appropriately selected from the above range.

4A and 4B are schematic views of an example of a substrate on which semiconductor chips are arranged, FIG. 4A is a top view, and FIG. 4B is a sectional view taken along line C-C′. In FIG. 4, reference numeral 40 denotes a substrate on which semiconductor chips are arranged (may be simply referred to as “substrate 40”), 41 denotes a semiconductor chip, 42 denotes a substrate, and 43 denotes a temporary fixing tape. The substrate 42 may be a wafer having a diameter of about 300 mm or a rectangular panel having a side of 300 mm or more. On the substrate 40, a plurality of semiconductor chips 41 are arranged and fixed (temporarily fixed) on the substrate 42 via a temporary fixing tape 43.

In the sheet-like prepreg of the present invention, it is preferable that the through hole and/or the recess is arranged at a position corresponding to the semiconductor chip mounting portion of the fan-out package. That is, in the sheet-like prepreg of the present invention, it is preferable that the through holes and/or the concave portions are arranged at positions corresponding to the semiconductor chips arranged and fixed (temporarily fixed) on the substrate.

FIG. 5 is a schematic view (cross-sectional view) showing an example of a process of sealing the semiconductor chips 41 arranged on the substrate 40 using a conventional sheet-like prepreg 50 (one having no through holes and no recesses). is there. When the sheet-like prepreg 50 is pressed and heated on the semiconductor chip 41 on the substrate 40 to cure, the conventional sheet-like prepreg 50 does not have sufficient followability to the uneven shape formed by the semiconductor chip 41 on the substrate 42. In this case, there is a problem that bubbles 52 tend to remain near the semiconductor chip 41 in the sealing material 51.

FIG. 6 is a schematic view (cross-sectional view) showing an example of a process of sealing the semiconductor chips 41 arranged on the substrate 40 using the sheet-like prepreg 20 of the present invention having the through holes 21. When the sheet-like prepreg 20 of the present invention is pressed and heated on the substrate 40 to cure, the semiconductor chip 41 is sealed so as to fit into the through hole 21, so that air bubbles are generated in the sealing material 61. Hard to do.
Even when the sheet-like prepreg 30 of the present invention having a recess is used in place of the sheet-like prepreg 20 of the present invention having a through hole, the semiconductor chip 41 is similarly sealed in the recess 31 so as to be fitted. , Bubbles are less likely to be generated in the sealing material.

The method for producing the sheet-like prepreg of the present invention having a through hole is not particularly limited, but for example, a flat sheet-like prepreg having no through hole (dried or semi-cured) is punched with a die or the like. It can be manufactured by punching.

The method for producing a sheet-like prepreg of the present invention having a recess is not particularly limited, for example, a sheet-like prepreg in a state where the curable composition is impregnated in the sheet-like porous support, a recessed shape and an inverted shape. It can be manufactured by pressing it against a molding die having convex portions, drying it under the same conditions as in the above-mentioned sheet-like prepreg production, and semi-curing it if necessary.
Alternatively, the sheet-like prepreg of the present invention having the above-mentioned through hole may be produced once and then laminated with a flat sheet-like prepreg having the same outer shape.

The shapes of the through holes and the recesses (the shape viewed from the top view) of the sheet-like prepreg of the present invention are not particularly limited, and may be square, rectangular, round, etc., but are the shapes that a semiconductor chip normally has. Squares and rectangles are preferred.

The depth of the recess of the sheet-like prepreg of the present invention is not particularly limited, but is preferably approximately the same as the height of the semiconductor chip, and can be appropriately selected from the range of 10 to 500 μm.

The area of the through hole and the recess (the area viewed from the top view) of the sheet-like prepreg of the present invention is not particularly limited, and it is preferable that the area is approximately the same as or slightly wider than the area of the semiconductor chip, and is in the range of 1 to 400 mm ² . It can be appropriately selected. That is, the area of the through hole and the recess of the sheet-like prepreg of the present invention is preferably about 100 to 150% of the area of the corresponding semiconductor chip. Even if the area of the through hole and the recess is wider than the corresponding semiconductor chip, the curable composition oozes out and fills the gap when the sheet-like prepreg of the present invention is compressed and heated. The chip can be reliably sealed.

Further, two or more sheet-like prepregs of the present invention may be laminated and used, or the sheet-like prepreg of the present invention and a flat sheet-like prepreg may be laminated and used. In that case, the film thickness of two or more sheet-like prepregs may be the same or different.

The sheet-like prepreg of the present invention may further have a curable resin layer laminated on at least one surface. Since the sheet-like prepreg of the present invention has the curable resin layer, the followability to the uneven shape of the semiconductor chip on the substrate is further improved, and bubbles are less likely to be generated. Therefore, the curable resin layer is preferably laminated on at least the surface of the substrate that contacts the semiconductor chip.

The curable composition forming the curable resin layer may be the same as or different from the curable composition forming the sheet-like prepreg of the present invention. The thickness of the curable resin layer is not particularly limited, but can be selected from, for example, 10 to 200 μm, preferably 20 to 100 μm. If the film thickness of the curable resin layer is smaller than this range, air bubbles may remain in the sealing material.

The method for laminating the curable resin layer is not particularly limited, but on one or both sides of the sheet-like prepreg of the present invention (which does not have the curable resin layer), under reduced pressure or vacuum, by printing or dispensing. An uncured or semi-cured curable resin layer can be formed by applying the curable composition, drying it, and then heating it if necessary. The drying and heating conditions can be the same as those for the sheet-like prepreg of the present invention. The curable resin layer may be formed before forming the through holes and/or recesses or after forming the through holes and/or recesses.

The film thickness of the sheet-like prepreg of the present invention is not particularly limited, but is, for example, 5 to 500 μm. The lower limit is preferably 10 μm, particularly preferably 15 μm, most preferably 20 μm. 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 sheet-like prepreg of the present invention exceeds the above range, it tends to be difficult to meet the demand for downsizing and weight saving of electronic devices. On the other hand, when the thickness is less than the above range, it tends to be difficult to obtain sufficient toughness, and it becomes difficult to increase the strength by packaging.

[Fan-out package manufacturing method]
The method for manufacturing a fan-out package of the present invention is characterized by using the sheet-like prepreg of the present invention. Specifically, it is a method including a step of sealing the semiconductor chips arranged on the substrate as described above with the sheet-like prepreg of the present invention.

FIG. 7 shows a schematic diagram (cross-sectional view) of an example of a method for manufacturing a fan-out package of the present invention using the sheet-like prepreg of the present invention.
The fan-out package of the present invention can be manufactured, for example, by a method including the following steps I to III.
Step I: A substrate 42 (wafer or panel) is pasted with a temporary fastening tape 43, and the semiconductor chip 41 is attached to the substrate 42 via the temporary fastening tape 43 to produce the substrate 40. Step II: Sheet-like prepreg of the present invention (Sheet-like prepreg 20 having a through hole in FIG. 7) for sealing the semiconductor chip 41 Step III: The substrate 42 is peeled off to obtain a reconstructed wafer 70.

The fan-out package manufacturing method of the present invention may further include the following step IV.
Step IV: Further, a rewiring layer and an electrode are formed, and dicing is performed to obtain a fan-out package.

As a method for sealing a semiconductor chip using the sheet-like prepreg of the present invention in the step II, for example, the sheet-like prepreg of the present invention is attached to a semiconductor chip on a substrate, and a surface-flattening substrate 71 or the like is used. It can be carried out by compressing (pressing at 0.1 to 5 MPa) using the composition and subjecting it to heat treatment by the above method.

Since the semiconductor chip fits into the through hole and/or the recess of the sheet-like prepreg of the present invention, bubbles are unlikely to remain in the sealing material.
At the same time as or after sealing the semiconductor chip with the sheet-like prepreg of the present invention, another sheet-like prepreg of the present invention or a flat sheet-like prepreg having no through holes and recesses is used for sealing. You may go.

The formation of the redistribution layer and the electrodes in step IV can be performed by a well-known and commonly used method. The rewiring layer and the electrodes are formed in a high temperature environment of about 200° C., but the cured product of the sheet-like prepreg of the present invention has a low coefficient of linear thermal expansion, so that the difference from the coefficient of thermal expansion of the semiconductor chip is suppressed. Therefore, it is possible to suppress warpage and cracks caused by the stress resulting from the difference from the coefficient of thermal expansion of the semiconductor chip.

[Electronics]
The electronic device of the present invention is provided with the fan-out package of the present invention. Since the fan-out package of the present invention is excellent in warpage prevention and crack resistance and the generation of bubbles in the encapsulant is suppressed, the electronic device of the present invention has high performance and excellent durability. Therefore, the electronic device of the present invention can be suitably used for portable electronic devices such as a mobile phone, a digital camera, a smartphone, a tablet terminal, and an electronic dictionary.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Preparation Example 1: Preparation of Support (Preparation of Cellulose Nonwoven Fabric)
The slurry of the microfiber Serish KY110N (manufactured by Daicel Co., Ltd.) was diluted to 0.2% by weight, and a No. 1 papermaking machine (standard square machine manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used. The 5C filter paper was used as a filter cloth for papermaking to obtain a cellulose nonwoven fabric in a wet state.
Blotting paper was placed on both surfaces of the obtained cellulose nonwoven fabric in a wet state, and pressed at a pressure of 0.2 MPa for 1 minute. Then, it is pressed at a pressure of 0.2 MPa for 1 minute, and further stuck to a drum dryer (made by Kumagai Riki Kogyo Co., Ltd.) whose surface temperature is set to 100° C. and dried for 120 seconds to give a cellulose nonwoven fabric (void). Ratio: 60 vol%, basis weight 9.9 g/m ² , thermal linear expansion coefficient: 5 ppm/K, thickness 25 μm) were obtained.

Preparation Example 2: Preparation of Support (Preparation of Cellulose Nonwoven Fabric)
A cellulose nonwoven fabric (porosity: 60 vol%, basis weight 9.9 g/m ² , thermal linear expansion coefficient: 5 ppm/K, thickness 200 μm) was obtained by the same method as in Preparation Example 1.

Examples 1-5
(Adjustment of sheet prepreg)
A curable composition was prepared according to the formulation shown in Table 1.
In the obtained curable composition, under reduced pressure, after dipping the cellulose nonwoven fabric obtained in Preparation Examples 1 and 2, or glass cloth, through solvent removal under reduced pressure and impregnation of the curable composition again, A flat sheet-like prepreg (having no through holes) was prepared. Table 1 shows the film thickness of the obtained sheet-like prepreg.

(Production of sheet-like prepreg having through holes)
The sheet-like prepreg obtained above was punched out to obtain 37 sheet-like prepregs having 37 10.5 mm square through holes shown in FIG.

Examples 6-12
(Manufacture of rebuilt wafers)
A PET double-sided adhesive film of the same diameter was stuck on a circular silicon wafer with a diameter of 6 inches, and 37 glass substrates cut into 10 mm squares were arranged on the entire surface at 10 mm intervals, and the substrate on which the semiconductor chips shown in FIG. 4 were arranged was arranged. Manufactured.
Next, in the combinations shown in Table 2, the sheet-like prepreg obtained above was laminated so that the positions of the through holes of the glass substrate and the sheet-like prepreg arranged on the substrate were aligned, and then 150° C. while applying pressure. Cured for 2 hours. The silicon wafer that had been temporarily adhered via the PET film was removed to obtain a reconstructed wafer for fan-out wafer level package (FOWLP) shown at 70 in FIG.

Comparative Example 1
(Manufacture of sealant)
100 g of bisphenol A glycidyl ether (YD128) and 187 g of silica filler were charged into a crusher (manufactured by Ishikawa Factory) and kneaded for 30 minutes to highly disperse the filler. Next, 87 g of RIKACID MH-700F, 2 g of ethylene glycol and 0.5 g of a curing accelerator (U-CAT 12XD) were added and kneaded to produce a sealing material containing 50 wt% of silica filler.

(Manufacture of rebuilt wafers)
The semiconductor chip was encapsulated by applying the encapsulant obtained above onto the substrate on which the semiconductor chips obtained above were arranged and curing the same at 150° C. for 2 hours while applying pressure. The silicon wafer that had been temporarily adhered via the PET film was removed to obtain a reconstructed wafer in which the rewiring layer was removed from the fan-out wafer level package (FOWLP) shown in FIG.

Comparative Examples 2 and 3
Reconstructed wafers were obtained in the same manner as in Examples 7 and 10 except that a sheet-like prepreg having no through holes was used.

[Evaluation]
The reconstructed wafers obtained in the above Examples and Comparative Examples were evaluated as follows.

(Glass transition temperature (Tg), coefficient of linear thermal expansion in temperature range lower than Tg (α ₁ ), coefficient of linear thermal expansion in temperature range higher than Tg (α ₂ ))
The glass transition temperature and the coefficient of linear thermal expansion of the reconstructed wafers obtained in the above Examples and Comparative Examples were measured under the following conditions. In addition, the measured value in 2nd-heating was employ|adopted for all. The results are shown in Table 2.
Test piece size: Initial length 10 mm × width 3.5 mm × thickness 0.035 mm
Measuring device: Thermomechanical analyzer (Exstar TMA/SS7100, manufactured by Hitachi High-Technologies Corporation)
Measurement mode: Tensile, constant load measurement (40mN)
Measurement atmosphere: Nitrogen temperature condition: 1st-heating-60 to 120°C, 5°C/min
cooling 120°C to -60°C, 20°C/min
2nd-heating-60°C to 220°C, 5°C/min

(Warp prevention property)
When the reconstructed wafers obtained in the above Examples and Comparative Examples were placed on a flat plate, the difference in height between the central portion and the edge portion from the flat plate was defined as “warpage”. The temperature of the flat plate was controlled to 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 warp prevention effect is “◯”, when the temperature is 200 to 1000 μm, the evaluation of the warp prevention effect is “Δ”, when the evaluation exceeds 1000 μm The evaluation of the warp prevention effect was rated as "x". The results are shown in Table 2.

(Via formation)
The reconstructed wafers obtained in the above Examples and Comparative Examples were formed with a 60 μmφ opening by a laser processing machine using a UV-YAG laser. After formation, the state of the bottom of the via was observed under a microscope to confirm the presence or absence of scum. The case where no foreign matter such as scum was observed was evaluated as “◯”, the case where slight foreign matter was observed was evaluated as “Δ”, and the case where many foreign matter was observed was evaluated as “x”. The results are shown in Table 2.

(Presence of bubbles)
The reconstructed wafers obtained in the above Examples and Comparative Examples were checked for the presence or absence of air bubbles around the 10 mm square glass substrate using X-ray. Out of 37 cells, the case where no bubbles were observed at all was designated as “◯”, the case where bubbles were observed at 1 to 4 was designated as “Δ”, and the case where bubbles were observed at 5 or more were designated as “x”. The results are shown in Table 2.

<Epoxy compound>
-YD-128: Bisphenol A type diglycidyl ether (epoxy equivalent 190, viscosity 13600 mPas/25°C), epoxy equivalent 188.6, Nippon Steel & Sumitomo Metal Corporation-EXA-4850-150: Modified epibis type glycidyl Ether type epoxy resin, epoxy equivalent: 433, trade name "EPICLON EXA-4850-150", manufactured by DIC <Curing agent>
* RIKACID MH-700F: Methylhexahydrophthalic anhydride, acid anhydride group equivalent 164.5, manufactured by Shin Nippon Rika Co., Ltd. RIKACID HF-08: Ester of alicyclic acid anhydride and polyalkylene glycol (Dicarboxylic acid), carboxyl group equivalent 672.7, Shin Nippon Rika Co., Ltd. TD2091: phenol novolac, hydroxyl group equivalent 104.0, DIC <hydroxyl group-containing compound>
・EG: ethylene glycol, Wako Pure Chemical Industries, Ltd. <solvent>
-2-butanone, 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. <silica filler>
・Silica filler: particle size 3 μm or less, manufactured by Nippon Electric Glass Co., Ltd. <glass cloth>
・Glass cloth: Porosity: 62 vol%, basis weight 24 g/m ² , thermal linear expansion coefficient: 3 ppm/k, thickness 25 μm, trade name “1037”, manufactured by Toyobo Co., Ltd.

10 Fan-out Package 11 Encapsulant 12 Semiconductor Chip 13 Rewiring Layer 20 Sheet-Shaped Prepreg (with Through Hole)
21 through hole 30 sheet-like prepreg (having a recess)
31 recess 40 substrate on which semiconductor chips are arranged (wafer or panel)
41 semiconductor chip 42 substrate (wafer or panel)
43 Temporary fastening tape 50 Sheet-like prepreg (having neither through-holes nor recesses)
51, 61 sealing material 70 reconstructed wafer 71 surface flattening substrate

Claims (11)

A sheet-like prepreg for sealing a fan-out package, which has a through hole and/or a recess. The sheet-shaped prepreg for sealing a fan-out package according to claim 1, wherein the through hole and/or the recess is arranged at a position corresponding to a semiconductor chip mounting portion of the fan-out package. The fan-out package encapsulation according to claim 1 or 2, wherein the cured product of the sheet-like prepreg for encapsulating a fan-out package has a coefficient of linear thermal expansion (α ₂ ) of 20 ppm/K or less in a temperature range of the glass transition temperature or higher. Sheet prepreg for use. The sheet-shaped prepreg for encapsulating a fan-out package according to claim 1, wherein a curable resin layer is laminated on at least one surface. The sheet-like prepreg for sealing a fan-out package according to claim 1, wherein two or more sheet-like prepregs are laminated. The sheet-shaped prepreg for encapsulating a fan-out package according to any one of claims 1 to 5, wherein the core material of the sheet-shaped prepreg is a nonwoven fabric of cellulose fiber. A method for manufacturing a fan-out package, comprising using the sheet-like prepreg for sealing a fan-out package according to claim 1. A fan-out package, wherein a semiconductor chip is sealed with a cured product of the sheet-shaped prepreg for sealing a fan-out package according to any one of claims 1 to 6. The fan-out package according to claim 8, which is a fan-out wafer level package or a fan-out panel level package. An electronic device comprising the fan-out package according to claim 8. Use of a sheet-like prepreg having a through hole and/or a recess as a fan-out package sealant.

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