JP7400926B2 - Thermosetting composition for forming stretchable resin, stretchable resin, and semiconductor device - Google Patents

Description

The present invention mainly relates to a thermosetting composition for forming a stretchable resin, and a semiconductor device having a stretchable resin layer formed using the thermosetting composition.

Resin members constituting wearable devices, biosensors, connector members, and the like may be required to have higher flexibility and stretchability than before. For example, resin members constituting wearable devices are required to have high flexibility and stretchability in order to be easily attached to curved surfaces of the body and to suppress connection failures that occur when attached and detached. Conventional stretchable resins with high flexibility and stretchability are generally formed by liquid silicone or liquid polyurethane.

However, stretchable resins made from liquid silicone may lack adhesion to other materials. Stretchable resins formed from liquid polyurethane tend to lack heat resistance.

On the other hand, Patent Document 1 discloses a moisture-proof insulating paint containing a copolymer rubber.

Japanese Patent Application Publication No. 2005-162986

Stretchable resins formed from thermosetting compositions containing epoxy resins tend to have high adhesion to other materials and high heat resistance. However, there is room for improvement in terms of elongation at break and stretchability of the stretchable resin.

Therefore, an object of one aspect of the present invention is to further improve the elongation at break and the stretchability of a stretchable resin formed by curing a thermosetting composition containing an epoxy resin.

One aspect of the present invention relates to a thermosetting composition for forming a stretchable resin, which contains (A) an epoxy resin and (B) a thiol compound having two or more thiol groups. (A) Epoxy resin contains (A1) copolymerized epoxy resin. (A1) The copolymerized epoxy resin is a copolymer containing a constitutional unit having an aromatic group or an alicyclic group and a constitutional unit having an oxyalkylene group or an alkylene group having 4 to 8 carbon atoms.

Another aspect of the present invention relates to a stretchable resin comprising a cured product of the thermosetting composition for forming stretchable resin. Yet another aspect of the present invention relates to a semiconductor device including a stretchable resin layer made of a cured product of the thermosetting composition for forming stretchable resin.

According to the present invention, a thermosetting composition capable of forming a stretchable resin having sufficient elongation at break and stretchability is provided. The stretchable resin formed has good properties in terms of heat resistance and adhesion to many materials. The thermosetting composition according to one aspect of the present invention also has excellent stability during storage. The thermosetting composition of the present invention can be solvent-free. Solvent-free thermosetting compositions are advantageous in terms of handling and productivity compared to solvent-containing thermosetting compositions.

It is a stress-strain curve showing an example of measurement of stretch recovery rate. FIG. 1 is a cross-sectional view showing one embodiment of a semiconductor device. FIG. 1 is a cross-sectional view showing an embodiment of a flexible board and a circuit component. FIG. 3 is a cross-sectional view showing an embodiment of a process for obtaining a plurality of semiconductor devices.

Hereinafter, one embodiment of the present invention will be specifically described, but the present invention is not limited thereto. It goes without saying that in the following embodiments, the constituent elements (including elemental steps, etc.) are not necessarily essential, except when explicitly stated or when it is considered to be clearly essential in principle. . This also applies to numerical values and ranges, and should not be construed as unduly limiting the present invention.

In this specification, the term "process" is used not only to refer to an independent process, but also to include a process in which the intended effect of the process is achieved even if the process cannot be clearly distinguished from other processes. .
In this specification, a numerical range indicated using "-" indicates a range that includes the numerical values before and after "-" as the minimum and maximum values, respectively.
When referring to the amount of each component in the composition herein, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, those multiple substances present in the composition means the total amount of

[Thermosetting composition for forming stretchable resin]
A thermosetting composition according to one embodiment contains (A) an epoxy resin and (B) a thiol compound having two or more thiol groups. (A) A copolymerized epoxy resin in which the epoxy resin is a copolymer containing (A1) a constitutional unit having an aromatic group or an alicyclic group and a constitutional unit having an oxyalkylene group or an alkylene group having 4 to 8 carbon atoms. Contains resin. When this thermosetting composition is cured by a reaction between an epoxy group and a thiol group, a stretchable resin having sufficient stretchability is formed. The thermosetting composition according to one embodiment may be a one-component thermosetting composition, or may be composed of (A) a base liquid containing an epoxy resin and (B) a curing agent liquid containing a thiol compound. It may be a two-component thermosetting composition.

As used herein, "stretchability" refers to the property of being able to recover to its original shape or a shape close to it upon release from the load after being strained by a tensile load. For example, a material that can recover to or near its original shape after being subjected to a 50% strain under a tensile load can be said to be stretchable. More specifically, a resin having a stretch recovery rate of 80% or more, which will be described later, can be said to be a stretchable resin.

<(A1) Copolymerized epoxy resin>
The copolymerized epoxy resin of component (A1) has a structural unit having an aromatic group or an alicyclic group as a rigid component, and a structural unit having an alkylene group having 4 or more carbon atoms as a flexible component. Copolymerized epoxy resins typically have two epoxy groups located at both ends of the copolymer chain. By using this copolymerized epoxy resin, it is possible to obtain a cured product that has both heat resistance reliability and flexibility.

The copolymerized epoxy resin is, for example, a copolymer of a diol having an aromatic group or an alicyclic group and a glycidyl ether having an alkylene group having 4 to 8 carbon atoms, or a copolymer of a diol having an alkylene group having 4 to 8 carbon atoms and an aromatic It may be a copolymer with a diglycidyl ether having a group group or an alicyclic group, or a combination thereof. The diol having an aromatic group or an alicyclic group may be a compound represented by the following formula (21). The glycidyl ether having an alkylene group having 4 or more carbon atoms may be a compound represented by the following formula (31). The diol having an alkylene group having 4 to 8 carbon atoms may be a compound represented by the following formula (22). The diol having an aromatic group or an alicyclic group may be a compound represented by the following formula (32). In these formulas, R ^a represents an aromatic group or an alicyclic group, and R ^b represents an alkylene group having 4 or more carbon atoms. R ^b may be an alkylene group having 4 to 8 carbon atoms.

The aromatic group may be, for example, an aromatic hydrocarbon group such as a benzene ring, a naphthalene ring, an anthracene ring, and a pyrene ring, or an aromatic heterocyclic group such as a pyrrole ring and a thiophene ring. The aromatic group may be a group having two or more aromatic rings, which are bonded by a direct bond, a methanediyl group, a 2,2-propanediyl group, a quaternary spiro carbon atom, or a combination thereof, Examples include a biphenylene group, a tetramethylbiphenylene group, a group having a cardo structure, and a fluorene ring. The alicyclic group may be, for example, a cyclohexane ring or a dicyclopentadiene group.

As the alkylene group having 4 or more carbon atoms, known ones can be used. For example, the alkylene group having 4 or more carbon atoms may be a 1,4-butanediyl group or a 1,6-hexanediyl group. The oxyalkylene group may be, for example, an oxyethylene group, an oxypropylene group, or an oxybutylene group.

Examples of copolymerized epoxy resins include copolymers of bisphenol F and 1,6-hexanediol diglycidyl ether, copolymers of 1,6-hexanediol and bisphenol F diglycidyl ether, and copolymers of bisphenol F and 1,4 - copolymer with butanediol diglycidyl ether, copolymer with 1,4-butanediol and bisphenol F diglycidyl ether, copolymer with bisphenol A and 1,6-hexanediol diglycidyl ether, 1, Copolymer of 6-hexanediol and bisphenol A diglycidyl ether, copolymer of bisphenol A and 1,4-butanediol diglycidyl ether, copolymer of 1,4-butanediol and bisphenol A diglycidyl ether , copolymer of tetramethylbiphenol and 1,6-hexanediol diglycidyl ether, copolymer of 1,6-hexanediol and tetramethylbiphenol diglycidyl ether, tetramethylbiphenol and 1,4-butanediol diglycidyl ether, Copolymer with glycidyl ether, copolymer with 1,4-butanediol and tetramethylbiphenol diglycidyl ether, copolymer with biphenol and 1,6-hexanediol diglycidyl ether, 1,6-hexanediol copolymer of biphenol and biphenol diglycidyl ether, copolymer of biphenol and 1,4-butanediol diglycidyl ether, copolymer of 1,4-butanediol and biphenol diglycidyl ether, 1,4-naphthalenediol and 1,6-hexanediol diglycidyl ether, 1,6-hexanediol and 1,4-naphthalenediol diglycidyl ether, 1,4-naphthalenediol and 1,4-butane Copolymer with diol diglycidyl ether, copolymer with 1,4-butanediol and 1,4-naphthalenediol diglycidyl ether, copolymer with 1,6-naphthalenediol and 1,6-hexanediol diglycidyl ether A copolymer, a copolymer of 1,6-hexanediol and 1,6-naphthalenediol diglycidyl ether, a copolymer of 1,6-naphthalenediol and 1,4-butanediol diglycidyl ether, and Examples include copolymers of 1,4-butanediol and 1,6-naphthalenediol diglycidyl ether. These may be used alone or in any combination of two or more.

(A1) Examples of commercially available copolymerized epoxy resins include "YX7105" and "YX7110" (copolymers of bisphenol F and 1,6-hexanediol diglycidyl ether) manufactured by Mitsubishi Chemical Corporation. .

The content of the copolymerized epoxy resin (A1) may be 30 parts by mass or more, or 50 parts by mass or more with respect to 100 parts by mass of the total amount of the epoxy resin (A). When the content of component (A1) is 30 parts by mass or more, a cured product having particularly high flexibility can be easily obtained.

<(B) Thiol compound having two or more thiol groups>
The thiol compound of component (B) has two or more thiol groups (-SH). (B) The thiol compound may have 2 to 5, 3 to 5, or 3 to 4 thiol groups. (B) The thiol group that the thiol compound has may be a secondary thiol group. A thermosetting composition containing a thiol compound having a secondary thiol group can have particularly excellent storage stability. A secondary thiol group is a thiol group bonded to a carbon atom that is bonded to two carbon atoms and one hydrogen atom.

(B) The thiol compound may be a compound represented by the following formula (1), (2) or (3).

In formula (1), X ¹ , X ² , X ³ and ^{X 4} each independently represent ^a monovalent group having ^a thiol group or ^a hydrogen atom; Two or more are monovalent groups having a thiol group. In formula (2), X ⁵ , X ⁶ and X ⁷ each independently represent a monovalent group having a thiol group or a hydrogen atom, and two or more of X ⁵ , X ⁶ and X ⁷ are thiol groups. It is a monovalent group having In formula (3), X ⁸ and X ⁹ each independently represent a monovalent group having a thiol group, and R ¹ represents an alkylene group. R ¹ may be an alkylene group having 2 to 10 carbon atoms. The group having a thiol group may be a group represented by the following formula (11) having a secondary thiol group, or a group represented by the following formula (12) or (13) having a primary thiol group. It may be. In formula (11), R ² represents an alkylene group. In formula (12), R ³ represents an alkylene group. In formula (13), R ⁴ represents an alkylene group. R ² may be an alkylene group having 1 to 8 carbon atoms. R ³ and R ⁴ may be alkylene groups having 2 to 10 carbon atoms.

Examples of the thiol compound having a secondary thiol group include pentaerythritol tetrakis (3-mercaptobutyrate) represented by the following formula (1a) (for example, "Karens MT PE-1" manufactured by Showa Denko K.K.), 1,3,5-tris(2-(3-mercaptobutyryloxy)ethyl)-1,3,5-triazine-2,4,6(1H,3H,5H) represented by the following formula (2a) - Trion (for example, “Karens MT NR-1” manufactured by Showa Denko K.K.) and 1,4-bis(3-mercaptobutyryloxy)butane represented by the following formula (3a) (for example, “Karens MT NR-1” manufactured by Showa Denko K.K.) ``Karens MT BD-1'' manufactured by Co., Ltd.).

Other examples of thiol compounds having secondary thiol groups include ethylene glycol bis(3-mercaptobutyrate), trimethylolethane tris(3-mercaptobutyrate), butanediol bis(3-mercaptobutyrate), penta Erythritol tris(3-mercaptobutyrate), trimethylolethane (3-mercaptobutyrate), trimethylolpropane tris(3-mercaptobutyrate), and dipentaerythritol hexakis(3-mercaptobutyrate).

Other examples of thiol compounds having a primary thiol group include pentaerythritol tripropanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1 ,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,10-decanedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 4,4'-thiobisbenzenedithiol , 4,4'-biphenyldithiol, 1,5-dimercaptonaphthalene, 4,5-bis(mercaptomethyl)-ortho-xylene, 1,3,5-benzenedithiol, 1,4-butanediol bis(thio glycolate), dithioethithritol, 3,6-dioxa-1,8-octanedithiol, 3,7-dithia-1,9-nonanedithiol, bis(2-mercaptoethyl) sulfide, ethylene glycol bis(mercaptoacetate) ), ethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(3-mercaptoisobutyrate), butanediol bis(mercaptoacetate), butanediol bis(3-mercaptopropionate), butanediol bis( 3-mercaptoisobutyrate), pentaerythritol tri(mercaptoacetate), pentaerythritol tri(3-mercaptopropionate), pentaerythritol tri(3-mercaptoisobutyrate), pentaerythritol tetrakis(mercaptoacetate), pentaerythritol Tetrakis (3-mercaptopropionate), Pentaerythritol Tetrakis (3-mercaptoisobutyrate), Trimethylolethane (Mercaptoacetate), Trimethylolethane (3-Mercaptopropionate), Trimethylolethane (3-Mercaptoisobutyrate) butyrate), trimethylolpropane tris (mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (3-mercaptoisobutyrate), dipentaerythritol hexakis (mercaptoacetate), dipentaerythritol hexakis (mercaptoacetate), Pentaerythritol hexakis (3-mercaptopropionate), dipentaerythritol hexakis (3-mercaptoisobutyrate), 1,4-bis(3-mercaptopropyloxy)butane, tris[(3-mercaptopropionyloxy) ethyl] isocyanurate, and tetraethylene glycol bis(3-mercaptopropionate).

The thiol compounds exemplified above can be used alone or in combination of two or more.

(B) Even if the thiol equivalent (equivalent of thiol group) of the thiol compound is 0.5 to 1.5 or 0.8 to 1.2 with respect to the epoxy equivalent of the total amount of the epoxy resin (A) good. When the thiol equivalent of the thiol compound is within this range, unreacted epoxy resin (A) and thiol compound (B) are unlikely to remain in the cured product.

<(A2) Monofunctional epoxy resin having an alkyl group having 6 or more carbon atoms>
The thermosetting composition according to one embodiment may further contain (A2) a monofunctional epoxy resin having an alkyl group having 6 or more carbon atoms as the epoxy resin (A). The monofunctional epoxy resin as component (A2) contains one or more epoxy compounds having an alkyl group having 6 or more carbon atoms and one epoxy group. The number of carbon atoms in the alkyl group may be 8 or more, 20 or less, or 17 or less. When the number of carbon atoms in the alkyl group is within these numerical ranges, the cured product tends not to become cloudy. (A2) The alkyl group having 6 or more carbon atoms that the monofunctional epoxy resin has may be a linear alkyl group.

(A2) The monofunctional epoxy resin may contain a glycidyl ether compound represented by the following formula (5), a glycidyl ester compound represented by the following formula (6), or a combination thereof. R ⁵ and R ⁶ in formulas (5) and (6) are alkyl groups having 6 or more carbon atoms.

(A2) Examples of monofunctional epoxy resins include glycidyl ether compounds having an alkyl group having 12 to 13 carbon atoms (for example, "ADEKA Glycilol ED-502" manufactured by ADEKA Co., Ltd.), and alkyl groups having 17 carbon atoms. Examples include glycidyl ester compounds having the following: (eg, "Denacol EX-1113" manufactured by Nagase ChemteX Co., Ltd.). These compounds can be used alone or in combination of two or more.

(A2) The content of the monofunctional epoxy resin may be 60 parts by mass or less, or 50 parts by mass or less, or 10 parts by mass or more, based on 100 parts by mass of the total amount of the epoxy resin (A). good. When the content of component (A2) is within these numerical ranges, a cured product as a stretchable resin tends to be particularly easily formed.

<(A3) Alicyclic group-containing polyfunctional epoxy resin>
The thermosetting composition according to one embodiment may contain (A3) an alicyclic group-containing polyfunctional epoxy resin as the (A) epoxy resin. The alicyclic group-containing polyfunctional epoxy resin of component (A3) is an epoxy resin having an alicyclic group and two or more epoxy groups, and is different from the copolymerized epoxy resin of component (A1). The alicyclic group may be, for example, a cyclohexane ring or a dicyclopentadiene group.

Examples of alicyclic group-containing polyfunctional epoxy resins include dicyclopentadiene type epoxy resins (for example, "EPICLON HP-7200 series" manufactured by DIC Corporation), 3,4-epoxycyclohexylmethyl-3',4'- Epoxycyclohexane carboxylate (for example, "Celoxide 2021P, Celoxide 2081, Celoxide 8000" manufactured by Daicel Corporation), hydrogenated bisphenol A epoxy resin (for example, "Epicote YX8000, Epicote YX8034, Epicote YL8040" manufactured by Mitsubishi Chemical Corporation) ), 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (for example, "EHPE3150" manufactured by Daicel Corporation), butanetetracarboxylic acid tetra (3,4-epoxycyclohexylmethyl)-modified ε-caprolactone (e.g., "Epolead GT-401" manufactured by Daicel Corporation), silicone oligomers having an alicyclic group and an epoxy group (e.g., "Epolead GT-401" manufactured by Daicel Corporation), X-40-2670''). From the viewpoint of heat resistance reliability, (A3) alicyclic-containing polyfunctional epoxy resin may contain a dicyclopentadiene type epoxy resin. These epoxy resins can be used alone or in combination of two or more.

(A3) The content of the alicyclic group-containing polyfunctional epoxy resin may be 5 parts by mass or more, or 10 parts by mass or more, and 50 parts by mass or less, based on 100 parts by mass of the total amount of the epoxy resin (A). , or 40 parts by mass or less. When the content of component (A3) is 5 parts by mass or more, a cured product with particularly high strength and heat resistance tends to be formed. When the content of component (A3) is 50 parts by mass or less, the cured product tends to exhibit even higher elasticity.

<Other ingredients>
In addition to the above-described (A) epoxy resin and (B) thiol compound, the thermosetting composition according to one embodiment may contain other components as necessary. The epoxy resin (A) may contain epoxy resins other than the components (A1), (A2), and (A3). However, the ratio of the total amount of components (A1), (A2) and (A3) to the total amount of epoxy resin (A) is usually 80 to 100% by mass or 90 to 100% by mass. The total amount of (A) epoxy resin and (B) thiol compound is 50 to 100% by mass, 60 to 100% by mass, 70 to 100% by mass, based on the mass of the thermosetting composition excluding the solvent. It may be 80 to 100% by mass, or 90 to 100% by mass.

The thermosetting composition according to one embodiment includes inorganic fine particles, a curing catalyst, an antifoaming agent, a leveling agent, a silane coupling agent, an antioxidant, an anti-yellowing agent, an ultraviolet absorber, a visible light absorber, and a colorant. , a plasticizer, and a flame retardant. Examples of inorganic fine particles include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), barium carbonate (BaCO ₃ ), talc (3MgO・4SiO ₂・H ₂ O), and zinc oxide (ZnO). ), barium sulfate (BaSO ₄ ), organic bentonite, and hydrotalcite. Examples of curing catalysts include tertiary amines, imidazoles, phosphorus compounds, quaternary ammonium salts, and organometallic salts. Defoamers and leveling agents can be silicone-based, fluorine-based, or polymeric, for example. The silane coupling agent can be, for example, thiazole-based or triazole-based. The thermosetting composition may be a resin varnish containing a solvent.

[Stretchable resin/stretchable resin layer]
The stretchable resin according to one embodiment is a cured product formed by thermosetting the thermosetting composition according to the embodiment described above. The stretchable resin can have any shape, and may form a stretchable resin layer, for example.

The stretchable resin or stretchable resin layer according to one embodiment can be used, for example, as a sealing layer or protective film of a wearable device, a biosensor, a connection connector member, or as a protective film of wiring of a flexible substrate.

The elongation at break of the stretchable resin in a tensile test may be 100% or more. Sufficient tensile strength can be obtained if the elongation at break is 100% or more.

The stretchability of the stretchable resin can be evaluated using the stretch recovery rate measured by the following procedure including two tensile tests as an index.
1) A strip of stretchable resin with a length of 40 mm and a width of 5 mm is prepared as a test piece.
2) While holding the test piece with a chuck with a distance between chucks of 20 mm, the test piece is pulled to a displacement (strain) X in the first tensile test.
3) Return the chuck to its initial position.
4) Perform a second tensile test and record the amount of displacement (strain) Y in the section where the load is applied.
5) Calculate the elasticity recovery rate using the equation: elasticity recovery rate R (%) = (Y/X) x 100.
The tensile test is conducted in a 25°C environment. X can be set to a displacement of 10 mm (50% strain). As the testing machine, for example, a micro force testing machine (Illinois Tool Works Inc., "Instron 5948") can be used. FIG. 1 is an example of a stress-strain curve obtained from a tensile test to determine the stretch recovery rate.

The stretch recovery rate may be 80% or more, 85% or more, or 90% or more from the viewpoint of durability against repeated use. The upper limit of the stretch recovery rate is 100%. The thermosetting composition according to the embodiment described above can usually easily form a cured product exhibiting a stretch recovery rate of 80%.

The tensile modulus of the stretchable resin may be 0.1 MPa or more and 50 MPa or less. When the tensile modulus is 0.1 MPa or more and 50 MPa or less, the stretchable resin can be expanded and contracted more easily. From the same viewpoint, the tensile modulus of the stretchable resin may be 0.1 MPa or more and 30 MPa or less, or 0.1 MPa or more and 10 MPa or less.

The stretchable resin or stretchable resin layer is prepared by disposing a thermosetting composition in a desired form by dispensing, dipping, various coatings, casting, etc., and then thermosetting the thermosetting composition. It can be formed by a method including. The heating conditions for thermal curing may be set within a range where thermal curing sufficiently proceeds, and may be, for example, a temperature of 100° C. to 200° C.

[Semiconductor device]
FIG. 2 is a cross-sectional view showing one embodiment of a semiconductor device. A semiconductor device 100 shown in FIG. 2 includes a stretchable flexible substrate 1, a circuit component 2, and a sealing resin layer 3. Circuit component 2 is mounted on flexible substrate 1. The sealing resin layer 3 can be a stretchable resin formed from the thermosetting composition according to the above embodiment. The sealing resin layer 3 seals the flexible substrate 1 and the circuit components 2, thereby protecting them.

The flexible substrate 1 may be a resin film containing at least one resin selected from the group consisting of polyimide resin, acrylic resin, silicone resin, urethane resin, bismaleimide resin, epoxy resin, and polyethylene glycol resin. From the viewpoint of excellent elasticity, the flexible substrate 1 may be made of polyimide resin, acrylic resin, silicone resin, urethane resin, long-chain alkyl chain (for example, alkyl having 1 to 20 carbon atoms) having a siloxane group, an aliphatic ether group, or a diene structure. The resin film may include at least one resin selected from the group consisting of a bismaleimide resin having a chain), an epoxy resin, and a polyethylene glycol resin having a rotaxane structure. From the same viewpoint, the flexible substrate 1 is made of at least one selected from the group consisting of polyimide resins having siloxane groups, aliphatic ether groups or diene structures, silicone resins, urethane resins, and bismaleimide resins having long alkyl chains. It may also be a resin film containing a seed resin.

The circuit component 2 can be one type or two or more types of components. The circuit component 2 may be, for example, a control circuit, a memory chip, a light emitting diode (LED), an RF tag (RFID), a temperature sensor, an acceleration sensor, or a combination thereof.

The semiconductor device 100 includes, for example, as shown in FIG. 3, a step of mounting a circuit component 2 on a flexible substrate 1, and a step of forming a sealing resin layer 3 for sealing the flexible substrate 1 and the circuit component 2. It can be manufactured by a method. The sealing resin layer 3 is formed by curing a film of a thermosetting composition formed on the flexible substrate 1. The film of the thermosetting composition can be formed, for example, by coating or printing the thermosetting composition on the flexible substrate 1 and the circuit components 2, or by immersing the flexible substrate 1 and the circuit components 2 in the thermosetting composition. can be formed by

If necessary, as shown in FIG. 4, a plurality of semiconductor devices may be obtained by forming a sealing structure including a plurality of parts that become semiconductor devices, and cutting and separating the structure. Thereby, a plurality of semiconductor devices can be manufactured at once.

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

1. Raw material (A1) Copolymerized epoxy resin YX7105: manufactured by Mitsubishi Chemical Corporation, copolymer of bisphenol F and 1,6-hexanediol diglycidyl ether, epoxy equivalent 487
(B) Thiol compound/PEPT: manufactured by SC Organic Chemical Co., Ltd., pentaerythritol tripropanethiol, trifunctional primary thiol, molecular weight 358.6
・PE-1: Karenz MT PE-1, manufactured by Showa Denko K.K., pentaerythritol tetrakis (3-mercaptobutyrate, tetrafunctional secondary thiol, molecular weight 544)
(A2) Monofunctional epoxy resin with an alkyl chain having 6 or more carbon atoms・ED-502: ADEKA Glycilol ED-502, manufactured by ADEKA Co., Ltd., glycidyl ether of alkyl alcohol having 12 or 13 carbon atoms, epoxy equivalent: 320
(A3) Alicyclic group-containing polyfunctional epoxy resin/HP-7200L: EPICLON HP-7200L, manufactured by DIC Corporation, dicyclopentadiene type epoxy resin, epoxy equivalent 248
(acid anhydride)
・HN-5500: Hitachi Chemical Co., Ltd., 3 or 4-methyl-hexahydrophthalic anhydride, molecular weight 168
(curing catalyst)
・2E4MZ: Curazole 2E4MZ, manufactured by Shikoku Kasei Co., Ltd., 2-ethyl-4-methylimidazole (other epoxy resins)
・Celoxide 2081: manufactured by Daicel Corporation, ε-caprolactone modified 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, epoxy equivalent 200
・Denacol EX-991L: manufactured by Nagase ChemteX Co., Ltd., polyether glycol diglycidyl ether, epoxy equivalent 450
・Denarex R15-EPT: Manufactured by Nagase ChemteX Co., Ltd., bifunctional epoxy resin containing polybutadiene/hydrogenated polybutadiene skeleton, epoxy equivalent: 910
・Denarex R45-EPT: Manufactured by Nagase ChemteX Co., Ltd., bifunctional epoxy resin containing polybutadiene/hydrogenated polybutadiene skeleton, epoxy equivalent 1570

2. Preparation Example 1 of resin varnish (thermosetting composition for forming stretchable resin)
Put 60.0 parts by mass of YX7105, 14.7 parts by mass of PEPT, and 0.1 parts by mass of Curesol 2E4MZ into a plastic container with a lid, and mix these mixtures with an autorotating/revolving mixer ("ARE-" manufactured by Shinky Co., Ltd.). 250'') to produce a resin varnish for forming a stretchable resin.

Examples 2 to 7, Comparative Examples 1 to 5
Resin varnishes of Examples 2 to 7 and Comparative Examples 1 to 5 were prepared in the same manner as Example 1 except that the blending ratio (parts by mass) shown in Table 1 was changed. The resin varnish of Comparative Example 1 contains an acid anhydride instead of the thiol compound (B). The resin varnishes of Comparative Examples 2 to 5 contain other epoxy resins having a flexible structure instead of the copolymerized epoxy resin (A1).

3. Preparation of film for evaluation: Apply a mold release agent (“Daifree GA-7500” manufactured by Daikin Industries, Ltd.) to the bottom of an aluminum container (L 102 mm x W 45 mm x H 23 mm), and apply the coating film using a hot air heating furnace. The bottom of the container was subjected to mold release treatment by heating at 120° C. for 3 minutes. Next, the resin varnishes of each example and comparative example were poured into an aluminum container. The resin varnish in the aluminum container was cured by heating at 120° C. for 1 hour to obtain an evaluation film (1 mm thick) consisting of a cured product of the thermosetting composition.

4. Evaluation [elastic modulus, elongation rate]
A test piece with a length of 40 mm and a width of 5 mm was cut out from the evaluation film. A tensile test of this test piece was conducted using an autograph (Shimadzu Corporation "EZ-S") to obtain a stress-strain curve. The elastic modulus and elongation at break of the cured product were determined from the obtained stress-strain curve. The tensile test was conducted under conditions of a distance between chucks of 20 mm and a tensile speed of 50 mm/min. The elastic modulus is a value under a load of 0.1 to 0.5N, and the elongation rate is the elongation at the time the test piece breaks (elongation at break). Since no cured product was formed from the resin varnish of Comparative Example 2, the elastic modulus and elongation rate of the cured product could not be measured.

[Stretch recovery rate]
A test piece with a length of 40 mm and a width of 5 mm was cut out from the evaluation film. A tensile test of this test piece was performed twice using a micro force tester ("Instron 5948" manufactured by Illinois Tool Works Inc.). The test piece was held between a pair of chucks, and tensile stress was applied to the test piece up to a displacement (strain) of X in the first tensile test. Next, the chuck was returned to the initial position, and a tensile test was performed again up to the displacement (strain) X, and the displacement (strain) Y in the section where the load was applied was measured. The stretch recovery rate R was determined by the formula: R=(Y/X)×100. In this measurement, the initial length (distance between chucks) was 20 mm, and X was 10 mm (50% strain). The film formed from the resin varnish of Comparative Example 4 broke before reaching 50% strain in the first tensile test.

[Adhesion with polyimide]
The resin varnish of each example was applied onto a polyimide film ("Kapton 200EN" manufactured by DuPont-Toray Co., Ltd.) with a thickness of 50 μm using a film applicator (Tester Sangyo Co., Ltd.). It was cured under the curing conditions shown in 2.The formed cured film was cut in a grid pattern at 1 mm intervals, and the cured film was divided into 100 square parts. The adhesive tape was strongly pressed and the end of the adhesive tape was peeled off at once at a 45° angle.Then, based on the number of square parts that did not peel off from the polyimide film out of 100 square parts, the adhesion was evaluated as follows. Evaluation was made on a three-level scale.
A: 100 (no peeling)
B:95-99
C: Less than 95

[Viscosity (storage stability)]
The viscosity of the resin varnish of each Example at the initial stage and at 25° C. after being stored at room temperature (25° C.) for 24 hours was measured using an E-type viscometer (“TVE25H” manufactured by Toki Sangyo Co., Ltd.). The storage stability of the resin varnish was evaluated based on the change in viscosity.

The cured product (stretchable resin) formed from the resin varnish of the example exhibited a high elongation at break of 130% or more, and a high elastic recovery rate of 90% or more. In particular, the cured products (stretchable resins) formed from the resin varnishes of Examples 3 to 7 exhibited extremely high elongation at break exceeding 200%. The resin varnishes of Examples 6 and 7 using thiol compounds having a secondary thiol group showed a small increase in viscosity after being stored at room temperature for 24 hours, and had excellent storage stability.

DESCRIPTION OF SYMBOLS 1... Flexible board, 2... Circuit component, 3... Sealing resin layer (stretchable resin), 100... Semiconductor device.

Claims (9)

(A) an epoxy resin;
(B) a thiol compound having two or more thiol groups;
Contains
(A) The epoxy resin includes (A1) a copolymerized epoxy resin that is a copolymer containing a constitutional unit having an aromatic group or an alicyclic group and a constitutional unit having an alkylene group having 4 or more carbon atoms.
A thermosetting composition for forming a stretchable resin,
(A1) The copolymerized epoxy resin is a copolymer of a diol having an aromatic group or an alicyclic group and a glycidyl ether having an alkylene group having 4 to 8 carbon atoms, or a diol having an alkylene group having 4 to 8 carbon atoms. Contains a copolymer with diglycidyl ether having an aromatic group or an alicyclic group, or a combination thereof,
The tensile modulus of the stretchable resin formed by thermosetting the thermosetting composition is 0.1 MPa or more and 2.2 MPa or less,
The tensile modulus is a value at a load of 0.1 to 0.5 N, determined from a stress-strain curve obtained by a tensile test of a test piece with a length of 40 mm, a width of 5 mm, and a thickness of 1 mm, and is carried out in an environment of 25°C, with a distance between chucks of 20 mm, and a pulling speed of 50 mm/min.
Thermosetting composition for forming stretchable resin. The thermosetting composition for forming a stretchable resin according to claim 1, wherein (A) the epoxy resin further comprises (A2) a monofunctional epoxy resin having an alkyl group having 6 or more carbon atoms. The thermosetting composition for forming a stretchable resin according to claim 2, wherein the monofunctional epoxy resin (A2) is a monofunctional epoxy resin having an alkyl group having 6 to 17 carbon atoms. (A) The epoxy resin further includes (A3) an alicyclic group-containing polyfunctional epoxy resin having an alicyclic group, and (A3) the alicyclic group-containing polyfunctional epoxy resin is different from (A1) the copolymerized epoxy resin. The thermosetting composition for forming a stretchable resin according to any one of claims 1 to 3, which is a compound. (A3) The thermosetting composition for forming a stretchable resin according to claim 4, wherein the alicyclic group-containing polyfunctional epoxy resin includes a dicyclopentadiene group-containing polyfunctional epoxy resin. The thermosetting composition for forming a stretchable resin according to any one of claims 1 to 5, wherein the thiol compound (B) contains a thiol compound having a secondary thiol group. The thermosetting resin for forming a stretchable resin according to any one of claims 1 to 6, wherein the content of the copolymerized epoxy resin (A1) is 50 parts by mass or more based on 100 parts by mass of the (A) epoxy resin. Composition. A stretchable resin comprising a cured product of the thermosetting composition for forming a stretchable resin according to any one of claims 1 to 7. A semiconductor device comprising a stretchable resin layer made of a cured product of the thermosetting composition for forming stretchable resin according to any one of claims 1 to 7.

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