JP2014173007A - Epoxy adhesive and lens-provided printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy adhesive which is hardenable at low temperatures, gives a hardened product after hardening white color or a color close to white and improves the adhesive strength of a lens.SOLUTION: An epoxy adhesive is used for fixing a lens 12 to a printed wiring board 11 mounted with an optical semiconductor 11a and comprises an epoxy compound having two or more epoxy groups, a thiol compound having two or more thiol groups, a latent hardening accelerator containing a nitrogen atom and an inorganic filler of a degree of whiteness of 70 or higher. The content of the inorganic filler is 1-30 wt.% in 100 wt.% of an epoxy adhesive. The epoxy adhesive contains no organic solvent or contains an organic solvent in a content of 5 wt.% or lower in 100 wt.% of the epoxy adhesive.

Description

  The present invention relates to an epoxy adhesive used for fixing a lens to a printed wiring board on which an optical semiconductor element is mounted. The present invention also relates to a printed wiring board using the epoxy adhesive and including an optical semiconductor element and a lens.

  Optical semiconductor elements such as light emitting diode (LED) elements are widely used as light sources for display devices. An optical semiconductor device using an optical semiconductor element has low power consumption and long life. Moreover, the said optical semiconductor device can be used also in a severe environment. Therefore, the optical semiconductor device is used in a wide range of applications such as a backlight for mobile phones, a backlight for liquid crystal televisions, an automobile lamp, a lighting fixture, and a signboard.

  Also, in backlight applications for liquid crystal televisions, the use of direct-type optical semiconductor devices that emit light with a printed wiring board on which an optical semiconductor element is mounted placed behind a liquid crystal screen is increasing. Compared with the edge-type optical semiconductor device, which emits light with the thin printed wiring board with the optical semiconductor element mounted on the side of the liquid crystal screen, the direct-type optical semiconductor device An installation area can be increased and heat dissipation can be improved. Therefore, the optical semiconductor device of the direct type has an advantage in terms of cost because it is not necessary to use a metal substrate or the like that is excellent in heat dissipation but high in cost. On the other hand, in the direct type optical semiconductor device, the light emitted from the optical semiconductor element is directly irradiated onto the screen without passing through the light guide plate or the like. For this reason, it is difficult for the direct-type optical semiconductor device to uniformly diffuse light over the entire screen. Therefore, in an optical semiconductor device of a direct type, a printed wiring board in which an optical semiconductor element is mounted and a lens is disposed above the optical semiconductor element is used in order to eliminate non-uniform light diffusion. It has been. The lens diffuses light.

  An adhesive is used to fix the lens to the printed wiring board. The lens is generally formed of a thermoplastic resin such as polymethyl (meth) acrylate, and the heat resistance of the lens is generally low. For this reason, the adhesive is required to be curable at a low temperature. Moreover, in order to effectively utilize the light reflected by the lens, the cured product of the adhesive is also required to be white. Further, the cured product of the adhesive is required to have a high adhesive strength so that the lens does not peel even when the printed wiring board is curved.

  Patent Document 1 below discloses an epoxy resin composition (adhesive) containing an epoxy resin having two or more epoxy groups, a polythiol compound having two or more thiol groups, a latent curing agent, and a solid organic acid. Is disclosed. The solid organic acid is basically insoluble in the mixture of the epoxy compound, the polythiol compound and the latent curing agent.

Japanese translation of PCT publication No. 2002-509178

  Although the conventional adhesive as described in Patent Document 1 can be cured at a low temperature, even if the cured product is not white or the cured product just after curing is substantially white, the optical semiconductor element at a later stage It may become colored and become white due to the influence of heat or light generated by.

  Further, the adhesive described in Patent Document 1 does not sufficiently consider the adhesive force. In particular, in the adhesive described in Patent Document 1, no consideration is given to the adhesiveness (fixing force) of the lens when the lens is bonded to a printed wiring board on which an optical semiconductor element is mounted.

  An object of the present invention is to provide an epoxy adhesive that can be cured at a low temperature, can make the cured product white or a color close to white, and can suppress peeling of the lens after fixing the lens. It is to be. Another object of the present invention is to provide a printed wiring board provided with a lens in which the epoxy adhesive is used, the cured product is white or a color close to white, and the cured product has high adhesive strength. is there.

  According to a wide aspect of the present invention, an epoxy adhesive used for fixing a lens to a printed wiring board on which an optical semiconductor element is mounted, an epoxy compound having two or more epoxy groups, and a thiol group , A latent curing accelerator having a nitrogen atom, and an inorganic filler having a whiteness of 70 or more, and the content of the inorganic filler is 1% in 100% by weight of the epoxy adhesive. Provided is an epoxy adhesive which is not less than 30% by weight and not more than 30% by weight, does not contain an organic solvent, or contains an organic solvent, and the content of the organic solvent in 100% by weight of the epoxy adhesive is 5% by weight or less Is done.

  In a specific aspect of the epoxy adhesive according to the present invention, when a cured product having a thickness of 50 μm is obtained, the reflectance of the cured product is 50% or more.

  It is preferable that the inorganic filler is titanium oxide. The inorganic filler is preferably rutile type titanium oxide. The titanium oxide is preferably surface-treated with alumina or silica.

  The epoxy compound preferably contains an epoxy compound represented by the following formula (1), a bisphenol A liquid epoxy compound, a bisphenol F liquid epoxy compound, a phenol novolac liquid epoxy compound, or a cresol novolac liquid epoxy compound. .

  The epoxy compound preferably contains an epoxy compound having three or more epoxy groups. The thiol compound preferably contains a thiol compound having a secondary thiol group.

  In a specific aspect of the epoxy adhesive according to the present invention, the epoxy adhesive further includes an antioxidant or a light stabilizer.

  In certain aspects of the epoxy adhesive according to the present invention, the epoxy adhesive comprises nanoclay.

  In a specific aspect of the epoxy adhesive according to the present invention, when the cured product is obtained by heating at 80 ° C. for 10 minutes, the cured product includes a sea-island structure including a sea part and an island part in the cured resin. Have

  On the specific situation with the epoxy adhesive which concerns on this invention, in the said hardened | cured material which has a sea-island structure, the elastic modulus in 23 degreeC of the said sea part is higher than the elastic modulus in 23 degreeC of the said island part.

  On the specific situation with the epoxy adhesive which concerns on this invention, in the said hardened | cured material which has a sea-island structure, the said sea part and the said island part are 95: 5-50: 50 by volume ratio.

  According to a wide aspect of the present invention, a printed wiring board on which an optical semiconductor element is mounted, a lens disposed on a surface of the printed wiring board on which the optical semiconductor element is mounted, and the printed wiring board There is provided a printed wiring board including a lens, which is formed by curing the above-described epoxy adhesive, and a cured product fixing the lens.

  On the specific situation with the printed wiring board provided with the lens which concerns on this invention, the said hardened | cured material has a sea-island structure containing a sea part and an island part in the hardened | cured resin.

  In a specific aspect of the printed wiring board including the lens according to the present invention, in the cured product having a sea-island structure, an elastic modulus at 23 ° C. of the sea part is higher than an elastic modulus at 23 ° C. of the island part. high.

  On the specific situation with the printed wiring board provided with the lens which concerns on this invention, in the said hardened | cured material which has a sea-island structure, the said sea part and the said island part are 95: 5-50: 50 by volume ratio.

  The epoxy adhesive according to the present invention includes an epoxy compound having two or more epoxy groups, a thiol compound having two or more thiol groups, a latent curing accelerator having a nitrogen atom, and an inorganic having a whiteness of 70 or more. And 100 wt% of the epoxy adhesive, the content of the inorganic filler is 1 wt% or more and 30 wt% or less, and the epoxy adhesive does not contain an organic solvent or an organic solvent And the content of the organic solvent in 100% by weight of the epoxy adhesive is 5% by weight or less, so that it can be cured at low temperature and the cured product after curing can be made white or a color close to white. it can. Furthermore, after the lens is fixed to the printed wiring board on which the optical semiconductor element is mounted using the epoxy adhesive according to the present invention, peeling of the lens can be suppressed.

FIG. 1 is a cross-sectional view schematically showing an example of a printed wiring board provided with a lens using an epoxy adhesive according to an embodiment of the present invention.

  Hereinafter, the present invention will be described in detail.

  The epoxy adhesive according to the present invention is used for fixing a lens to a printed wiring board on which an optical semiconductor element is mounted. The epoxy adhesive according to the present invention includes an epoxy compound (A) having two or more epoxy groups, a thiol compound (B) having two or more thiol groups, and a latent curing accelerator (C) having a nitrogen atom. And an inorganic filler (D) having a whiteness of 70 or more. In 100% by weight of the epoxy adhesive according to the present invention, the content of the inorganic filler is 1% by weight or more and 30% by weight or less. The epoxy adhesive according to the present invention does not contain an organic solvent, or contains an organic solvent, and the content of the organic solvent in 100% by weight of the epoxy adhesive is 5% by weight or less. Even if the epoxy adhesive which concerns on this invention contains the said organic solvent, content of the said organic solvent is very small, and is 5 weight% or less.

  Since the epoxy adhesive according to the present invention has the above-described configuration, it can be cured at a low temperature. For example, the epoxy adhesive according to the present invention can be cured at 90 ° C. or lower and can be cured at 80 ° C. or lower. Therefore, when the epoxy adhesive according to the present invention is used to fix a lens to a printed wiring board on which an optical semiconductor element is mounted, thermal degradation of the lens can be suppressed. For example, when the lens is formed of a thermoplastic resin such as polymethyl (meth) acrylate, the heat resistance of the lens is low. By using the epoxy adhesive according to the present invention, it is possible to prevent the lens from being exposed to a high temperature when the epoxy adhesive is cured, even if the heat resistance of the lens is relatively low. Can be suppressed.

  Furthermore, since the epoxy adhesive according to the present invention has the above-described configuration, the cured product after curing can be white or a color close to white. When the lens is fixed using a conventional adhesive that can be cured at low temperatures, the cured product is not white or the whiteness of the cured product is relatively low. There is a problem that cannot be utilized. On the other hand, the use of the epoxy adhesive according to the present invention can fully utilize the light emission of the optical semiconductor element.

  In addition, since the epoxy adhesive according to the present invention has the above-described configuration, the cured product has high adhesiveness after fixing the lens to the printed wiring board on which the optical semiconductor element is mounted. Lens peeling can be suppressed.

  Although it is preferable that the said epoxy adhesive does not contain the said organic solvent, it originates in the organic solvent contained in the compounding raw material, and a trace amount of the said organic solvent may be contained in the said epoxy adhesive. When the epoxy adhesive contains the organic solvent, the lower the content of the organic solvent, the better. In 100% by weight of the epoxy adhesive, the content of the organic solvent is preferably 5% by weight or less, more preferably 1% by weight or less.

  The adhesive is preferably liquid at 23 ° C. In order to improve the handling property at the time of adhesion, the viscosity at 25 ° C. of the adhesive is preferably 0.1 Pa · s or more, more preferably 1 Pa · s or more, further preferably 5 Pa · s or more, preferably 100 Pa · s. Hereinafter, it is more preferably 80 Pa · s or less. When the viscosity is equal to or higher than the lower limit, the epoxy adhesive tends to stay at a predetermined position during bonding, and it is difficult to excessively wet and spread at an unintended position. Furthermore, when the viscosity is equal to or more than the lower limit, it is possible to prevent the thickness of the cured product from being excessively thinned, to increase the adhesiveness of the cured product, and to further suppress the peeling of the lens. be able to. When the viscosity is less than or equal to the above upper limit, application of the adhesive by dispensing or the like becomes even easier.

  The thixotropy index of the epoxy adhesive is preferably 1.1 or more, more preferably 1.3 or more, still more preferably 1.5 or more, preferably 10 or less, more preferably 8 or less, still more preferably 5 or less. When the thixotropy index is equal to or greater than the lower limit, the epoxy adhesive tends to stay in a predetermined position even when the lens is pressed when the lens is fixed, and it is difficult to wet and spread excessively at an unintended position. Furthermore, when the thixotropic index is equal to or more than the above lower limit, the thickness of the cured product after bonding can be prevented from becoming excessively thin, the adhesiveness of the cured product can be increased, and the lens can be further peeled off. Can be suppressed. When the thixotropy index is below the above upper limit, when the lens is pressed when the lens is fixed, the epoxy adhesive is sufficiently wetted and spread on the surface of the lens, and the adhesion of the cured product can be increased, and the lens is peeled off. Can be further suppressed.

  The thixotropy index means the ratio (η1 / η2) of the viscosity η1 of the epoxy adhesive at 23 ° C. and 1 rpm to the viscosity η2 of the epoxy adhesive at 23 ° C. and 10 rpm.

  The viscosity is measured using an E-type viscometer, and can be measured under conditions of 1 rpm and 10 rpm using, for example, a “TV22 viscometer” apparatus manufactured by Toki Sangyo Co., Ltd.

  Next, the detail of each component contained in the epoxy adhesive which concerns on this invention is demonstrated.

(Epoxy compound (A))
The epoxy compound (A) is not particularly limited as long as it has two or more epoxy groups. As the epoxy compound (A), an epoxy compound having two or more conventionally known epoxy groups can be used. The epoxy compound (A) having two or more epoxy groups is cured at a low temperature by the action of the thiol compound (B) and the latent curing accelerator (C). As for the said epoxy compound (A), only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of controlling the viscosity and thixotropy index of the adhesive to a more suitable range, the epoxy compound (A) is preferably liquid at 23 ° C.

  Specific examples of the epoxy compound include an epoxy monomer having a bisphenol skeleton, an epoxy monomer having a dicyclopentadiene skeleton, an epoxy monomer having a naphthalene skeleton, an epoxy monomer having an adamantane skeleton, an epoxy monomer having a fluorene skeleton, and a biphenyl skeleton. Epoxy monomer, epoxy monomer having bi (glycidyloxyphenyl) methane skeleton, epoxy monomer having xanthene skeleton, epoxy monomer having anthracene skeleton, epoxy monomer having disulfide skeleton, epoxy monomer having urethane skeleton, epoxy having aliphatic skeleton Examples thereof include an epoxy monomer having a flexible skeleton such as a monomer and butadiene, and an epoxy monomer having a pyrene skeleton. These hydrogenated products or modified products may be used. As for these epoxy compounds, only 1 type may be used and 2 or more types may be used together.

  Examples of the epoxy monomer having a bisphenol skeleton include epoxy monomers having a bisphenol skeleton such as a bisphenol A skeleton, a bisphenol F skeleton, and a bisphenol S skeleton.

  Examples of the epoxy monomer having a dicyclopentadiene skeleton include dicyclopentadiene dioxide and a phenol novolac epoxy monomer having a dicyclopentadiene skeleton.

  Examples of the epoxy monomer having a naphthalene skeleton include 1-glycidylnaphthalene, 2-glycidylnaphthalene, 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1,7-diglycidyl. Naphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, 1,2,5,6-tetraglycidylnaphthalene and the like can be mentioned.

  Examples of the epoxy monomer having an adamantane skeleton include 1,3-bis (4-glycidyloxyphenyl) adamantane and 2,2-bis (4-glycidyloxyphenyl) adamantane.

  Examples of the epoxy monomer having a fluorene skeleton include 9,9-bis (4-glycidyloxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3-methylphenyl) fluorene, and 9,9-bis (4- Glycidyloxy-3-chlorophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-bromophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-fluorophenyl) fluorene, 9,9-bis (4-Glycidyloxy-3-methoxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dimethylphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dichlorophenyl) Fluorene and 9,9-bis (4-glycidyloxy-3,5-dibromophenyl) Fluorene, and the like.

  Examples of the epoxy monomer having a biphenyl skeleton include 4,4'-diglycidylbiphenyl and 4,4'-diglycidyl-3,3 ', 5,5'-tetramethylbiphenyl.

  Examples of the epoxy monomer having a bi (glycidyloxyphenyl) methane skeleton include 1,1′-bi (2,7-glycidyloxynaphthyl) methane, 1,8′-bi (2,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,7-glycidyloxynaphthyl) methane, 1,8′-bi (3,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,5-glycidyloxynaphthyl) methane 1,8'-bi (3,5-glycidyloxynaphthyl) methane, 1,2'-bi (2,7-glycidyloxynaphthyl) methane, 1,2'-bi (3,7-glycidyloxynaphthyl) Examples include methane and 1,2′-bi (3,5-glycidyloxynaphthyl) methane.

  Examples of the epoxy monomer having a xanthene skeleton include 1,3,4,5,6,8-hexamethyl-2,7-bis-oxiranylmethoxy-9-phenyl-9H-xanthene.

  From the viewpoint of further improving the heat resistance, the epoxy compound (A) is an epoxy compound represented by the following formula (1), a bisphenol A liquid epoxy compound, a bisphenol F liquid epoxy compound, or a phenol novolac liquid. It is preferable to contain an epoxy compound or a cresol novolac type liquid epoxy compound. The liquid epoxy compound is liquid at 23 ° C.

  From the viewpoint of further improving the heat resistance, the epoxy compound (A) preferably contains an epoxy compound having three or more epoxy groups.

  The molecular weight of the epoxy compound (A) is not particularly limited. The molecular weight of the epoxy compound (A) is preferably less than 10,000. The molecular weight of the epoxy compound (A) is preferably 200 or more, more preferably 1200 or less, still more preferably 600 or less, and particularly preferably 550 or less. When the molecular weight of the epoxy compound (A) is equal to or higher than the lower limit, the volatility of the epoxy compound (A) is decreased, and the storage stability of the adhesive is further increased. When the molecular weight of the epoxy compound (A) is not more than the above upper limit, the adhesiveness of the cured product is further enhanced.

  In the present specification, the molecular weight in the epoxy compound (A) means a molecular weight that can be calculated from the structural formula when it is not a polymer and when the structural formula can be specified. Means weight average molecular weight.

  In 100% by weight of the epoxy adhesive, the content of the epoxy compound (A) is preferably 10% by weight or more, more preferably 20% by weight or more, preferably 80% by weight or less, more preferably 70% by weight or less. . When the content of the epoxy compound (A) is not less than the above lower limit and not more than the above upper limit, the heat resistance is further improved.

(Thiol compound (B))
The thiol compound (B) is not particularly limited as long as it has two or more thiol groups. As the thiol compound (B), a conventionally known thiol compound having a thiol group can be used. The thiol compound (B) has a role of increasing the low temperature curability of the epoxy compound (A). As for the said thiol compound (B), only 1 type may be used and 2 or more types may be used together.

  As the thiol compound (B), an aliphatic polythiol compound or an aromatic polythiol compound may be used. Furthermore, a polythiol compound having a sulfide bond may be used as the thiol compound (B).

  Examples of the dithiol compound that is the aliphatic polythiol compound and has two thiol groups include 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1, 6-hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 2,2-dimethyl-1,3- Propanedithiol, 3-methyl-1,5-pentanedithiol, 2-methyl-1,8-octanedithiol, 1,4-cyclohexanedithiol, 1,4-bis (mercaptomethyl) cyclohexane, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, bicyclo [2,2,1] hept -Exo-cis-2,3-dithiol, 1,1-bis (mercaptomethyl) cyclohexane, bis (2-mercaptoethyl) ether, ethylene glycol bis (2-mercaptoacetate), and ethylene glycol bis (3-mercaptopro Pionate).

  Examples of the trithiol compound that is the aliphatic polythiol compound and has three thiol groups include 1,1,1-tris (mercaptomethyl) ethane, 2-ethyl-2-mercaptomethyl-1,3-propanedithiol, 2,3-propanetrithiol, trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), tris [(mercaptopropionyloxy) -ethyl] isocyanurate, and the like. .

  Examples of the polythiol compound that is an aliphatic polythiol compound and has four or more thiol groups include pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), and pentaerythritol tetrakis (3-mercapto). Butyrate) and dipentaerythritol hexa-3-mercaptopropionate.

  Examples of the aromatic polythiol compound include 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis (mercaptomethyl) benzene, 1,3-bis (mercapto). Methyl) benzene, 1,4-bis (mercaptomethyl) benzene, 1,2-bis (2-mercaptoethyl) benzene, 1,3-bis (2-mercaptoethyl) benzene, 1,4-bis (2-mercapto) Ethyl) benzene, 1,2-bis (2-mercaptoethyleneoxy) benzene, 1,3-bis (2-mercaptoethyleneoxy) benzene, 1,4-bis (2-mercaptoethyleneoxy) benzene, 1,2, 3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, 1, , 3-Tris (mercaptomethyl) benzene, 1,2,4-tris (mercaptomethyl) benzene, 1,3,5-tris (mercaptomethyl) benzene, 1,2,3-tris (2-mercaptoethyl) benzene 1,2,4-tris (2-mercaptoethyl) benzene, 1,3,5-tris (2-mercaptoethyl) benzene, 1,2,3-tris (2-mercaptoethyleneoxy) benzene, 1,2 , 4-Tris (2-mercaptoethyleneoxy) benzene, 1,3,5-tris (2-mercaptoethyleneoxy) benzene, 1,2,3,4-tetramercaptobenzene, 1,2,3,5-tetra Mercaptobenzene, 1,2,4,5-tetramercaptobenzene, 1,2,3,4-tetrakis (mercaptomethyl) benzene, 1,2, , 5-tetrakis (mercaptomethyl) benzene, 1,2,4,5-tetrakis (mercaptomethyl) benzene, 1,2,3,4-tetrakis (2-mercaptoethyl) benzene, 1,2,3,5- Tetrakis (2-mercaptoethyl) benzene, 1,2,4,5-tetrakis (2-mercaptoethyl) benzene, 1,2,3,4-tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,3 5-tetrakis (2-mercaptoethyleneoxy) benzene, 1,2,4,5-tetrakis (2-mercaptoethyleneoxy) benzene, 2,2′-mercaptobiphenyl, 4,4′-thiobis-benzenethiol, 4, 4'-dimercaptobiphenyl, 4,4'-dimercaptobibenzyl, 2,5-toluenedithiol, 3,4-tolue Dithiol, 1,4-naphthalenedithiol, 1,5-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7-naphthalenedithiol, 2,4-dimethylbenzene-1,3-dithiol, 4,5-dimethylbenzene 1,3-dithiol, 9,10-anthracenedimethanethiol, 1,3-bis (2-mercaptoethylthio) benzene, 1,4-bis (2-mercaptoethylthio) benzene, 1,2-bis (2 -Mercaptoethylthiomethyl) benzene, 1,3-bis (2-mercaptoethylthiomethyl) benzene, 1,4-bis (2-mercaptoethylthiomethyl) benzene, 1,2,3-tris (2-mercaptoethyl) Thio) benzene, 1,2,4-tris (2-mercaptoethylthio) benzene, 1,3,5-tris ( -Mercaptoethylthio) benzene, 1,2,3,4-tetrakis (2-mercaptoethylthio) benzene, 1,2,3,5-tetrakis (2-mercaptoethylthio) benzene, and 1,2,4 Examples include 5-tetrakis (2-mercaptoethylthio) benzene.

  Examples of the polythiol compound having a sulfide bond include bis (2-mercaptoethyl) sulfide, bis (2-mercaptoethylthio) methane, 1,2-bis (2-mercaptoethylthio) ethane, 1,3-bis (2 -Mercaptoethylthio) propane, 1,2,3-tris (2-mercaptoethylthio) propane, tetrakis (2-mercaptoethylthiomethyl) methane, 1,2-bis (2-mercaptoethylthio) propanethiol, 2 , 5-Dimercapto-1,4-dithiane, bis (2-mercaptoethyl) disulfide, 3,4-thiophenedithiol, 1,2-bis (2-mercaptoethyl) thio-3-mercaptopropane, and bis- (2 -Mercaptoethylthio-3-mercaptopropane) sulfide and the like.

  From the viewpoint of further improving heat resistance, the thiol compound (B) preferably contains a thiol compound having 3 or more thiol groups, and preferably contains an aliphatic polythiol compound. The number of thiol groups in the thiol compound (B) is generally 8 or less. From the viewpoint of further improving the heat resistance, the thiol compound (B) is trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), tris [(mercaptopropionyloxy). ) -Ethyl] isocyanurate, pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutanate), or dipentaerythritol hexa-3-mercaptopro Pionate is preferred.

  From the viewpoint of further improving heat resistance, the thiol compound (B) preferably contains a thiol compound having a secondary thiol group, and preferably contains a compound having two or more secondary thiol groups. preferable. From the viewpoint of making the heat resistance even better, the thiol compound (B) is pentaerythritol tetrakis (3-mercaptobutyrate), trimethylolpropane tris (3-mercaptobutyrate), or trimethylolethane tris (3 -Mercaptobutyrate).

  The content of the thiol compound (B) is preferably 20 parts by weight or more, more preferably 30 parts by weight or more, preferably 200 parts by weight or less, more preferably 150 parts by weight with respect to 100 parts by weight of the epoxy compound (A). Or less. When the content of the thiol compound (B) is not less than the above lower limit and not more than the above upper limit, the heat resistance is further improved.

(Latent curing accelerator (C))
The latent curing accelerator (C) is not particularly limited as long as it has a nitrogen atom. As the latent curing accelerator (C), a conventionally known latent curing accelerator having a nitrogen atom can be used. The latent curing accelerator (C) has a role of increasing the low temperature curability of the epoxy compound (A). As for the said latent hardening accelerator (C), only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further suppressing coloring after curing and coloring over time, the latent curing accelerator (C) is dicyandiamide, polyamidoamine, imidazole compound, hydrazide compound, polyamine, urea compound, or a modified product thereof. It is preferable that These latent curing accelerators (C) may be microencapsulated.

  The latent curing accelerator (C) is a polyamidoamine, an amine adduct of an imidazole compound, or a microcapsule of an imidazole compound from the viewpoint of achieving both low-temperature curability and storage stability at a higher level. It is particularly preferred.

  Commercially available products of the latent curing accelerator (C) include “Novacure HX3941HP”, “Novacure HX3921HP”, “Novacure HX3721”, “Novacure HX3722”, and “Novacure HX3748” manufactured by Asahi Kasei Chemicals Co., Ltd., which are imidazole microcapsules. , “Novacure HX3088”, “Novacure HX3741”, “Novacure HX3742”, “Novacure HX361”; “Amicure PN-23”, “Amicure PN-H”, “Amicure PN-” produced by Ajinomoto Co., which is an amine adduct of an imidazole compound "31", "Amicure PN-40", "Amicure PN-50", "Amicure PN-F", "Amicure PN-23J", "Amicure PN-31J", "Amicure PN-40J", "Amicure MY-" 4 ”,“ Amicure MY-H ”;“ VDH ”,“ VDH-J ”,“ UDH ”,“ UDH-J ”manufactured by Ajinomoto Co., which is a hydrazide compound; Fuji Kasei Co., Ltd., a polyamine-modified latent curing accelerator "Fujicure FXR-1020", "Fujicure FXR-1030", "Fujicure FXR-1071", "Fujicure FXR-1211"; "Tomide 275", "Tomide" manufactured by Fuji Kasei Co., Ltd., a polyamidoamine type latent curing accelerator HR-11 "," Tomide 255-A "," Tomide 245-HS "," Tomide 235-S "," Tomide 225-E "," Tomide 252-A "," Tomide 245-S "," Tomide 245 " "," Tomide 235-A "," Tomide 225-X "," Tomide 215-X "," -Tomide 210 "," Tomide 2510 "," Tomide 235-R "," Tomide 2602 "," Tomide 225-R "," Tomide 292 "," Tomide 290-CA "," Tomide 290-F "; "Omicure U-210", "Omicure U-210M", "Omicure U-24", "Omicure U-24M", "Omicure U-35", "Omicure U-" manufactured by Emerald Performance Materials, Inc. 35M "," Omicure U-52 "," Omicure U-52M "," Omicure U-405 "," Omicure U-405M "," Omicure U-410 "," Omicure U-410M "," Omicure U-415 " ", Omicure U-415M" and the like.

  The content of the active ingredient of the latent curing accelerator (C) is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, preferably 100 parts by weight with respect to 100 parts by weight of the epoxy compound (A). It is 30 parts by weight or less, more preferably 30 parts by weight or less. When the content of the latent curing accelerator (C) is not less than the above lower limit, the epoxy adhesive can be cured at a lower temperature or more quickly. When the content of the latent curing accelerator (C) is not more than the above upper limit, the storage stability of the epoxy adhesive is further improved.

(Inorganic filler (D))
The inorganic filler (D) is not particularly limited as long as the whiteness is 70 or more. As the inorganic filler (C), a conventionally known inorganic filler having a whiteness of 70 or more can be used. When the whiteness of the inorganic filler (D) is 70 or more, the cured product can be white or a color close to white, the concealability by the cured product can be increased, and the heat resistance of the cured product can be increased. Can be increased. The said inorganic filler (D) has a role which makes hardened | cured material white or a color close | similar to white. As for the said inorganic filler (D), only 1 type may be used and 2 or more types may be used together.

  Examples of the inorganic filler (D) include silica, talc, clay, kaolin, mica, wollastonite, magnesium oxide, magnesium carbonate, barium sulfate, aluminum hydroxide, calcium carbonate, and titanium oxide.

  The whiteness of the inorganic filler (D) is preferably 80 or more, more preferably 90 or more, and still more preferably from the viewpoint of making the cured product white and further enhancing the concealability by the cured product and the heat resistance of the cured product. Is 95 or more, particularly preferably 99 or more. The higher the whiteness, the better.

  From the viewpoint of making the cured product white and further enhancing the concealability by the cured product and the heat resistance of the cured product, the inorganic filler (D) is particularly preferably titanium oxide.

  The inorganic filler is preferably rutile titanium oxide. Anatase-type titanium oxide has high activity as a photocatalyst and tends to promote deterioration of the resin over time. Since the catalytic activity of the rutile type titanium oxide is lower than that of the anatase type titanium oxide, the storage stability of the epoxy adhesive using the rutile type titanium oxide is further increased.

  The titanium oxide and the rutile titanium oxide are preferably surface-treated with alumina or silica. Surface treatment with alumina or silica further increases the storage stability of the epoxy adhesive.

  The average particle diameter of the inorganic filler (D) is not particularly limited. The average particle diameter of the inorganic filler (D) is preferably 0.1 μm or more, and preferably 20 μm or less. The said inorganic filler (D) disperse | distributes favorably in the said epoxy adhesive as the said average particle diameter is more than the said minimum. When the average particle diameter is not more than the above upper limit, the application thickness of the epoxy adhesive can be controlled to a more suitable range, and the peeling of the lens can be further suppressed after fixing the lens. The “average particle diameter” is an average particle diameter obtained from a volume average particle size distribution measurement result measured by a laser diffraction particle size distribution measuring apparatus.

  In 100% by weight of the epoxy adhesive, the content of the inorganic filler (D) is 1% by weight or more and 30% by weight or less. In 100% by weight of the epoxy adhesive, the content of the inorganic filler (D) is preferably 2% by weight or more, more preferably 3% by weight or more, preferably 20% by weight or less, more preferably 10% by weight or less. . As the content of the inorganic filler increases, the cured product becomes white or a color closer to white. When the content of the inorganic filler is not less than the above lower limit and not more than the above upper limit, it is possible to easily confirm the adhesion state of the lens visually after fixing the lens. Further, when the content of the inorganic filler (D) is not less than the above lower limit, when a cured product having a thickness of 30 μm is obtained using the epoxy adhesive, the reflectance of the cured product is set to 50% or more. Is easy.

(Antioxidant, light stabilizer)
The epoxy adhesive preferably contains an antioxidant or a light stabilizer. By using an antioxidant or a light stabilizer, even if the cured product is exposed to heat and UV generated from the optical semiconductor element for a long time, the whiteness of the cured product is maintained high. The epoxy adhesive may contain the antioxidant, may contain the light stabilizer, and may contain both the antioxidant and the light stabilizer. As for the said antioxidant and the said light stabilizer, only 1 type may be used respectively and 2 or more types may be used together.

  Examples of the antioxidant include hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, amine antioxidants, and lactone antioxidants.

  Examples of the hindered phenol antioxidant include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylenebis [3- (3,5-di-tert). -Butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N′-hexane-1,6-diylbis [3- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionamide], benzenepropanoic acid, 3,5-bis (1,1-dimethylethyl) -4-hydroxy, C7-C9 side chain alkyl ester, 3, 3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ″-(mesitylene- , 4,6-triyl) tri-p-cresol, 4,6-bis (dodecylthiomethyl) -o-cresol, 4,6-bis (octylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3, 5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-tris [(4-tert-Butyl-3-hydroxy-2,6-xylyl) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di- t rt-butyl-4- [4,6-bis (octylthio) -1,3,5-triazin-2-ylamino] phenol, diethyl [{3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl } Methyl] phosphonate and the like.

  Examples of the phosphorus-based antioxidant include tris (2,4-di-tert-butylphenyl) phosphite, tris [2-[[2,4,8,10-tetra-tert-butyldibenzo [d, f]. [1,3,2] dioxaphosphine-6-yl] oxy] ethyl] amine, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis [2,4-bis ( 1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphorous acid, tetrakis (2,4-di-tert-butylphenyl) (1,1-biphenyl) -4,4′-diylbisphosphonite Etc.

  Examples of the lactone-based antioxidant include a reaction product of 3-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene.

  The antioxidant preferably contains both a phenolic antioxidant that is a primary antioxidant and a phosphorus antioxidant that is a secondary antioxidant. By using the phenolic antioxidant and the phosphorus antioxidant together, the progress of the thermal oxidation deterioration cycle can be further suppressed. The antioxidant preferably contains a phenolic antioxidant that is a primary antioxidant, a phosphorus antioxidant that is a secondary antioxidant, and a lactone antioxidant. The lactone antioxidant captures alkyl radicals in the thermal oxidative degradation cycle and suppresses the progress of the thermal oxidative degradation cycle at the radical generation point.

  Examples of the light stabilizer include hindered amine light stabilizers. The light stabilizer is preferably a hindered amine light stabilizer.

  Examples of the hindered amine light stabilizer include dibutylamine, 1,3,5-triazine, N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine, Polycondensate with N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5 -Triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] Bis (1,2,2,6,6-pentamethyl-4-piperidyl) [{3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl} methyl] butyl malonate, and bis ( 2,2,6,6-tetra Chill 4-piperidyl) sebacate, and the like.

  In 100% by weight of the epoxy adhesive, the content of the antioxidant or the light stabilizer is preferably 0.1% by weight or more, more preferably 0.3% by weight or more, and further preferably 0.7% by weight. As mentioned above, Preferably it is 10 weight% or less, More preferably, it is 5 weight% or less, More preferably, it is 3 weight% or less. When the content of the antioxidant or the light stabilizer is equal to or more than the lower limit, discoloration of the cured product is further suppressed. When the content of the antioxidant or the light stabilizer is not more than the above upper limit, after the lens is fixed, the adhesiveness between the cured product and the lens is further increased, and the peeling of the lens is further suppressed. In addition, when the epoxy adhesive contains both the antioxidant and the light stabilizer, the content of the antioxidant or the light stabilizer is the amount of the antioxidant and the light stabilizer. It means the total content.

(Nano clay)
The epoxy adhesive preferably contains nanoclay. The epoxy adhesive contains nanoclay as a filler other than the inorganic filler (D) or the inorganic filler (D). The epoxy adhesive preferably contains nanoclay as the inorganic filler (D). By using nanoclay, even if the cured product is exposed to heat generated from the optical semiconductor element, the adhesive strength of the cured product is maintained high. As for the said nano clay, only 1 type may be used and 2 or more types may be used together.

  Examples of the nanoclay include smectite, mica, bentonite, montmorillonite, and kaolin.

  The nanoclay may be organically treated so as to be easily dispersed in the epoxy compound (A). Typical organic treatment includes treatment with quaternary ammonium, quaternary phosphonium, rosin and fatty acid.

  In 100% by weight of the epoxy adhesive, the content of the nanoclay is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, still more preferably 1.0% by weight or more, preferably 20% by weight. Hereinafter, it is more preferably 10% by weight or less, still more preferably 5% by weight or less. When the content of the nanoclay is not less than the above lower limit, the adhesive strength of the cured product is further maintained even at a high temperature. When the content of the nanoclay is not more than the above upper limit, the adhesion between the cured product and the lens is further increased after the lens is fixed, and the peeling of the lens is further suppressed.

(Other ingredients)
The epoxy adhesive may contain a tackifier, a plasticizer, a coupling agent, a thixotropic agent, a flame retardant, a photosensitizer, a colorant, and the like as necessary.

(Printed wiring board with epoxy adhesive, cured product, and lens)
When the epoxy adhesive is heated at 80 ° C. for 10 minutes to obtain a cured product, the cured product preferably has a sea-island structure including a sea part and an island part in the cured resin. By having such a sea-island structure, the toughness of the resin is increased, the adhesiveness between the cured product and the lens is further enhanced after the lens is fixed, and the lens is further prevented from peeling.

  In the cured product having a sea-island structure, the elastic modulus of the sea part (continuous layer) is preferably higher than the elastic modulus of the island part (dispersion layer). When such a relationship of the elastic modulus is satisfied, after the lens is fixed, the adhesiveness between the cured product and the lens is further increased, and the peeling of the lens is further suppressed.

  The elastic modulus can be measured using a dynamic viscoelasticity measuring device under conditions of 5 ° C./min. Examples of the dynamic viscoelasticity measuring apparatus include “DMS6100” manufactured by SII Nano Technology.

  In the cured product having a sea-island structure, the sea part and the island part are preferably in a volume ratio (volume of the sea part: volume of the island part) of 95: 5 to 50:50, and 90:10 More preferably, it is 70:30. By satisfying such a volume ratio, after the lens is fixed, the adhesiveness between the cured product and the lens is further increased, and the separation of the lens is further suppressed.

  The sea-island structure may be formed by phase separation at the time of curing, or may be formed by previously adding a component that becomes an island part such as rubber particles to the epoxy adhesive.

  The rubber particles for forming the sea-island structure are not particularly limited, but acrylic rubber particles, butadiene rubber particles, isoprene rubber particles, acrylonitrile butadiene rubber particles, styrene butadiene rubber particles, styrene isoprene rubber particles, urethane rubber particles, silicone rubber Examples thereof include particles, fluororubber particles, and natural rubber particles.

  The rubber particles may be single rubber particles or core-shell rubber particles.

  The average particle diameter of the rubber particles is not particularly limited. The average particle diameter of the rubber particles is preferably 0.1 μm or more, and preferably 30 μm or less. When the average particle size is not less than the lower limit, the rubber particles are easily dispersed in the epoxy adhesive. When the average particle size is not more than the above upper limit, the adhesion between the cured product and the lens is further enhanced after the lens is fixed, and the separation of the lens is further suppressed. The “average particle diameter” is an average particle diameter obtained from a volume average particle size distribution measurement result measured by a laser diffraction particle size distribution measuring apparatus.

  In order to form the sea-island structure, additives other than the rubber particles may be used. Examples of additives other than the rubber particles include silicone polymers, acrylonitrile butadiene polymers, polyurethanes, polybutadienes, polyisoprenes, (meth) acrylic polymers, thermoplastic polymers such as styrene polymers and natural rubber polymers, and copolymer polymers thereof. And modified products thereof.

  From the viewpoint of forming a good sea-island structure, a terminal carboxy-modified acrylonitrile butadiene polymer (CTBN) or a terminal amine-modified acrylonitrile butadiene polymer (ATBN) is preferably used.

  The contents of the rubber particles and additives other than the rubber particles are appropriately adjusted in order to form the sea-island structure.

  When a cured product having a thickness of 50 μm is obtained using the epoxy adhesive, the reflectance (Y value) of the cured product is preferably 50% or more. The reflectance is more preferably 60% or more, still more preferably 70% or more. The reflectance is adjusted by using a cured product obtained by curing the epoxy adhesive with a bar coater or screen printing so that the thickness of the cured product obtained is 50 μm and then heating at 80 ° C. for 10 minutes. Measured.

  The epoxy adhesive according to the present invention is used for fixing a lens to a printed wiring board on which an optical semiconductor element is mounted. Since the hardened | cured material of the epoxy adhesive which concerns on this invention is white or a color close | similar to white, when it uses for the printed wiring board which mounts an optical semiconductor element, the utilization efficiency of light can be improved.

  A printed wiring board including the lens according to the present invention includes a printed wiring board on which an optical semiconductor element is mounted, a lens disposed on a surface of the printed wiring board on which the optical semiconductor element is mounted, and the above And a cured product in which the lens is fixed to the printed wiring board. The cured product is formed by curing the epoxy adhesive.

  In FIG. 1, an example of the printed wiring board provided with the lens using the epoxy adhesive which concerns on one Embodiment of this invention is typically shown with sectional drawing.

  1 includes a printed wiring board 11 on which an optical semiconductor element 11a is mounted, and a lens disposed on the upper surface of the printed wiring board 11 on which the optical semiconductor element 11a is mounted. 12 and a cured product 13 in which the lens 12 is fixed to the printed wiring board 11. The lens 12 includes a lens body and a connection portion for fixing the lens 12 to the printed wiring board 11 on the side opposite to the lens surface of the lens body. The connecting part is a convex part. The upper surface of the printed wiring board 11 and the lower surface of the connecting portion of the lens 12 are bonded by a cured product 13. The lens body of the lens 12 is disposed above the optical semiconductor element 11a. Accordingly, the light emitted upward from the optical semiconductor element 11 a passes through the lens 12 and is emitted from the lens 12. A white resist 14 is disposed on the upper surface of the printed wiring board 11 at the side of the lens 12.

  In the printed wiring board including the lens according to the present invention, it is preferable that the cured product has a sea-island structure including a sea part and an island part in the cured resin. In the printed wiring board provided with the lens according to the present invention, in the cured product, the elastic modulus at 23 ° C. of the sea part is preferably higher than the elastic modulus at 23 ° C. of the island part. In the printed wiring board provided with the lens according to the present invention, in the cured product, the sea part and the island part have a volume ratio (volume of the sea part: volume of the island part) of 95: 5 to 50:50. It is preferable that the ratio is 90:10 to 70:30.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. The present invention is not limited to the following examples.

  The following materials were prepared.

[Epoxy compound (A)]
(1) Bisphenol A type liquid epoxy resin (“Epicoat 828” manufactured by Mitsubishi Chemical Corporation, Mw = 370)
(2) Bisphenol F type liquid epoxy resin (“Epicoat 806” manufactured by Mitsubishi Chemical Corporation, Mw = 342)
(3) Phenol novolac type epoxy resin (“Epicoat 152” manufactured by Mitsubishi Chemical Corporation, Mw = 530)
(4) Cresol novolac type epoxy resin (“EPICLON N-660” manufactured by DIC, Mw = 890)
(5) Alicyclic epoxy resin ("Celoxide 2021P" manufactured by Daicel Corporation, Mw = 252.3)

[Thiol Compound (B)]
(1) Trimethylolpropane tris (3-mercaptopropienate) (“TMMP” manufactured by SC Organic Chemical Co., Ltd.)
(2) Pentaerythritol tetrakis (3-mercaptopropienate) (“TEMPIC” manufactured by SC Organic Chemical Co., Ltd.)
(3) Pentaerythritol tetrakis (3-mercaptobutyrate)

[Curing agents other than thiol compound (B)]
(1) Alicyclic skeleton acid anhydride (“MH-700” manufactured by Shin Nippon Rika Co., Ltd.)

[Latent curing accelerator (C)]
(1) Amine adduct type imidazole (“Amicure PN-23” manufactured by Ajinomoto Fine Techno Co., Ltd.)
(2) Polyaminoamide ("Tomide 290-F" manufactured by Fuji Kasei)
(3) Solid modified amine compound ("Fuji Cure FXR-1030" manufactured by Fuji Chemical Co., Ltd.)
(4) Microcapsule type imidazole ("Novacure HX-3722" manufactured by Asahi Kasei E-Materials)

[Latent curing accelerators other than latent curing accelerator (C)]
(1) Triphenylphosphine [Inorganic filler (D)]
(1) Alumina surface-treated rutile titanium oxide (average particle size 0.26 μm, whiteness 99)
(2) Alumina / silica surface-treated rutile titanium oxide (average particle size 0.25 μm, whiteness 99)
(3) Anatase type titanium oxide (average particle size 0.15 μm, whiteness 99)
(4) Talc (average particle size 2.7 μm, whiteness 95)
(5) Mica (average particle size 9 μm, whiteness 86)
(6) Silica (average particle size 8 μm, whiteness 93)
(7) Clay (average particle size 7 μm, whiteness 70)
(8) Smectite (average particle size: 0 μm, whiteness: 80)

[Fillers other than inorganic filler (D)]
Bentonite (average particle size 2μm, whiteness 55)

[Ingredients for forming sea-island structure]
(1) Acrylonitrile butadiene rubber (2) Terminal carboxy-modified acrylonitrile butadiene rubber (3) Acrylic rubber particles (“KW4426” manufactured by Mitsubishi Rayon Co., Ltd., average particle size 5 μm)
(4) Silicone rubber particles ("Torefill E601" manufactured by Toray Dow Corning Co., Ltd., average particle size 2 μm)

[Other additives]
(1) Surface hydrophobized fumed silica (“MT-10” manufactured by Tokuyama Corporation, average particle size 15 nm)
(2) Phenol antioxidant ("Irganox Q1010" manufactured by Ciba Specialty Chemicals)
(3) Phosphorus antioxidant ("Irgafoss 168" manufactured by Ciba Specialty Chemicals)
(4) N-OR type HALS (“TINUVIN XT855” manufactured by Ciba Specialty Chemicals)

(Examples 1-42 and Comparative Examples 1-4)
Using a homodisper-type stirrer, the components shown in the following Tables 1 to 5 excluding the latent curing accelerator are blended in the contents shown in the following Tables 1 to 5 (the blending unit is parts by weight) and kneaded. A kneaded product was obtained. In addition, with respect to Example Zero 17 and Example 30, in order to nano-disperse smectite to less than 1 μm, kneading was further performed with three rolls to obtain a kneaded product. Next, the latent curing accelerators shown in Tables 1 to 5 below are blended in the obtained kneaded materials with the contents shown in Tables 1 to 5 below (the blending unit is parts by weight) and do not apply strong shear. The mixture was gently stirred at a low speed to prepare an epoxy adhesive.

(Evaluation)
(1) Curability 1 mg of epoxy adhesive was dropped between two 1 cm × 1 cm polymethyl methacrylate plates and heated in an oven at 80 ° C. for 10 minutes to cure the epoxy adhesive. The curability of the epoxy adhesive at the time of curing was determined according to the following criteria.

[Criteria for curability]
◯: Epoxy adhesive is completely solidified △: Epoxy adhesive is solidified, but moves when pressed lightly with a finger ×: Epoxy adhesive is not liquid and hardened

(2) Storage stability The epoxy adhesive was left in an oven at 25 ° C. for 24 hours. The viscosity before standing and the viscosity after standing were compared. The viscosity was measured using a “TV22 viscometer” manufactured by Toki Sangyo Co., Ltd. at 23 ° C. under the conditions of 1 rpm and 10 rpm. Storage stability was determined according to the following criteria.

[Criteria for storage stability]
◯: The viscosity after standing is less than 1.5 times the viscosity before leaving ◯: The viscosity after standing is 1.5 times or more and less than 2 times the viscosity before leaving △: The viscosity after standing is left as it is It is more than twice the previous viscosity, but the epoxy adhesive is not solidified ×: The epoxy adhesive is solidified

(3) Measurement of shear adhesive strength CEM3 having a thickness of 3 cm × 3 cm and a thickness of 1 mm prepared by etching all metals was prepared. 1 mg of an epoxy adhesive was applied to the central portion of the CEM 3, a 1 cm × 1 cm polymethyl methacrylate plate was placed thereon, and the epoxy adhesive was cured at 80 ° C. for 10 minutes to obtain a laminate. The die shear strength of the polymethyl methacrylate plate of the obtained laminate was measured at room temperature of 23 ° C.

(4) PCT · Measurement of Shear Adhesion Strength After 24 Hours CEM3 having a thickness of 3 cm × 3 cm and a thickness of 1 mm was prepared by etching all metals. 1 mg of an epoxy adhesive was applied to the central portion of the CEM 3, a 1 cm × 1 cm polymethyl methacrylate plate was placed thereon, and the epoxy adhesive was cured at 80 ° C. for 10 minutes to obtain a laminate. The obtained laminate was treated with PCT for 24 hours and then aged at 23 ° C. and 50% RH. The die shear strength of the polymethylmethacrylate plate was measured at room temperature of 23 ° C.

(5) Measurement of shear adhesive strength at 60 ° C. A CEM 3 having a thickness of 3 cm × 3 cm and a thickness of 1 mm prepared by etching all metals was prepared. 1 mg of an epoxy adhesive was applied to the central portion of the CEM 3, a 1 cm × 1 cm polymethyl methacrylate plate was placed thereon, and the epoxy adhesive was cured at 80 ° C. for 10 minutes to obtain a laminate. The die shear strength of the polymethyl methacrylate plate of the obtained laminate was measured at room temperature of 60 ° C.

(6) Adhesiveness A polymethyl methacrylate film having a size of 1 cm × 10 cm and a thickness of 1 mm was prepared. 1 mg of epoxy adhesive is applied to the center of this polymethyl methacrylate film, a 1 cm × 1 cm polymethyl methacrylate plate is placed thereon, and the epoxy adhesive is cured at 80 ° C. for 10 minutes to obtain a laminate. It was. Whether or not the polymethyl methacrylate plate was peeled when the obtained laminate was wound around cylinders having different diameters was observed. Adhesiveness was determined according to the following criteria.

[Adhesion criteria]
○○: Polymethylmethacrylate plate does not peel off even if it is wound around a cylinder with a diameter of 5 cm. ○: Polymethylmethacrylate plate does not peel off even if it is wound around a cylinder with a diameter of 10 cm. The polymethyl methacrylate plate does not peel off, but the polymethyl methacrylate plate peels off when wound around a cylinder with a diameter of 10 cm. X: When wound around a cylinder with a diameter of 20 cm, the polymethyl methacrylate plate peels off.

(7) Reflectance (Y value)
An epoxy adhesive was applied to a thickness of 50 μm on a 35 μm thick polyethylene terephthalate (PET) film using a bar coater, and cured at 80 ° C. for 10 minutes to obtain a cured product having a thickness of 50 μm. The Y value of the surface of the obtained cured product was measured using a color / color difference meter (“CR-400” manufactured by Konica Minolta). The Y value was taken as the reflectance. The reflectance (Y value) was determined according to the following criteria.

[Criteria for reflectance Y value]
○: Reflectance (Y value) is 70% or more ○: Reflectance (Y value) is 60% or more and less than 70% Δ: Reflectance (Y value) is 50% or more and less than 60% ×: Reflectivity ( Y value) is less than 50%

(8) Heat-resistant discoloration The cured product obtained by the evaluation of the above (7) reflectance (Y value) was prepared. The cured product was irradiated with UV for 24 hours in an oven at 80 ° C. using a UV irradiation device (EFOS LITE, manufactured by Sanei Tech Co., Ltd.) having a lamp power of nominal 50 W, and then the reflectance (Y value) was measured. From the reflectance Y value after UV irradiation, heat discoloration was determined according to the following criteria.

[Judgment criteria for heat discoloration]
○: Reflectance (Y value) is 70% or more ○: Reflectance (Y value) is 60% or more and less than 70% Δ: Reflectance (Y value) is 50% or more and less than 60% ×: Reflectivity ( Y value) is less than 50%

(9) State of sea-island structure A cured product obtained by the evaluation of the above (7) reflectance (Y value) was prepared. The cross section of the cured product was observed using a scanning electron microscope (SEM) at an area of 1 mm × 1 mm. The state of the sea-island structure was observed. Further, the elastic modulus at 23 ° C. of the sea part and the elastic modulus at 23 ° C. of the island part in the sea-island structure were evaluated. The relationship between the elastic part and the sea part was determined according to the following criteria. Furthermore, the volume ratio between the sea and the island was evaluated.

[Relationship between elastic modulus of sea and island]
A: The elastic modulus at 23 ° C of the sea part is higher than the elastic modulus at 23 ° C of the island part. B: The elastic modulus of the sea part at 23 ° C is equal to or less than the elastic modulus of the island part at 23 ° C. Shown in Tables 1-5.

DESCRIPTION OF SYMBOLS 1 ... Printed wiring board provided with lens 11 ... Printed wiring board 11a ... Optical semiconductor element 12 ... Lens 13 ... Hardened | cured material 14 ... White resist

Claims (17)

An epoxy adhesive used for fixing a lens to a printed wiring board on which an optical semiconductor element is mounted,
An epoxy compound having two or more epoxy groups, a thiol compound having two or more thiol groups, a latent curing accelerator having a nitrogen atom, and an inorganic filler having a whiteness of 70 or more,
In 100% by weight of the epoxy adhesive, the content of the inorganic filler is 1% by weight or more and 30% by weight or less,
The epoxy adhesive which does not contain an organic solvent, or contains an organic solvent, and content of the said organic solvent in 100 weight% of epoxy adhesives is 5 weight% or less.   The epoxy adhesive according to claim 1, wherein when a cured product having a thickness of 50 μm is obtained, the reflectance of the cured product is 50% or more.   The epoxy adhesive according to claim 1 or 2, wherein the inorganic filler is titanium oxide.   The epoxy adhesive according to claim 3, wherein the inorganic filler is rutile titanium oxide.   The epoxy adhesive according to claim 3 or 4, wherein the titanium oxide is surface-treated with alumina or silica. The epoxy compound contains an epoxy compound represented by the following formula (1), a bisphenol A liquid epoxy compound, a bisphenol F liquid epoxy compound, a phenol novolak liquid epoxy compound, or a cresol novolac liquid epoxy compound. The epoxy adhesive of any one of 1-5.

  The epoxy adhesive according to any one of claims 1 to 6, wherein the epoxy compound contains an epoxy compound having three or more epoxy groups.   The epoxy adhesive according to claim 1, wherein the thiol compound contains a thiol compound having a secondary thiol group.   The epoxy adhesive according to any one of claims 1 to 8, further comprising an antioxidant or a light stabilizer.   The epoxy adhesive according to any one of claims 1 to 9, comprising nanoclay.   When heating at 80 degreeC for 10 minutes and obtaining hardened | cured material, the said hardened | cured material has a sea island structure containing a sea part and an island part in hardened resin, In any one of Claims 1-10. The epoxy adhesive described.   The epoxy adhesive according to claim 10, wherein the cured product having a sea-island structure has an elastic modulus at 23 ° C. of the sea part higher than an elastic modulus at 23 ° C. of the island part.   The epoxy adhesive according to claim 11 or 12, wherein the sea part and the island part have a volume ratio of 95: 5 to 50:50 in the cured product having a sea-island structure. A printed wiring board on which an optical semiconductor element is mounted;
A lens disposed on a surface of the printed wiring board on which the optical semiconductor element is mounted;
A cured product fixing the lens to the printed wiring board,
The printed wiring board provided with the lens in which the said hardened | cured material is formed by hardening the epoxy adhesive of any one of Claims 1-13.   The printed wiring board provided with the lens according to claim 14, wherein the cured product has a sea-island structure including a sea part and an island part in the cured resin.   In the said hardened | cured material which has a sea island structure, the elastic modulus in 23 degreeC of the said sea part is higher than the elastic modulus in 23 degreeC of the said island part, The print provided with the lens of any one of Claim 15 Wiring board.   The printed wiring board provided with the lens according to claim 15 or 16, wherein in the cured product having a sea-island structure, the sea part and the island part have a volume ratio of 95: 5 to 50:50.

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