JP2014202821A - Manufacturing method of liquid crystal display element, and joint material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a liquid crystal display element, capable of obtaining a liquid crystal display element less warped, with suppressed thermal degradation and having high connection reliability.SOLUTION: A manufacturing method of a liquid crystal display element 1 includes the steps of: arranging a joint material layer on a surface of a substrate 2 using joint material containing curable component; arranging a semiconductor chip 4 on a surface of the joint material layer and performing tentative press bonding, and before the tentative press bonding, in the tentative press bonding or before a regular press bonding after the tentative press bonding, irradiating the joint material layer with light to thereby obtain a laminate in which the substrate 2, the joint material layer, and the semiconductor chip 4 are tentatively press bonded; heating the laminate at a temperature equal to or higher than 80°C and equal to or lower than 120°C without heating the laminate at a temperature over 120°C to perform the regular press bonding, thereby curing the joint material layer to form a cured layer 3 and obtaining the liquid crystal display element 1 in which the substrate 2, the cured layer 3, and the semiconductor chip 4 are regularly press bonded.

Description

  The present invention relates to a method for manufacturing a liquid crystal display element in which a substrate and a semiconductor chip are connected using a bonding material in the liquid crystal display element. The present invention also relates to a bonding material used in the method for manufacturing the liquid crystal display element.

  Pasty or film-like anisotropic conductive materials are widely known. In the anisotropic conductive material, a plurality of conductive particles are dispersed in a binder resin or the like.

  In order to obtain various connection structures, the anisotropic conductive material is, for example, a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)) or a connection between a semiconductor chip and a flexible printed circuit board (COF ( Chip on Film)), connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)), and the like.

  As an example of the manufacturing method of the connection structure, the following Patent Document 1 uses an anisotropic conductive adhesive including a low temperature side curing component and a high temperature side curing component having different thermosetting mechanisms and including conductive particles. A method for manufacturing a connection structure is disclosed. Here, the anisotropic conductive adhesive is heated and pressed at a reaction temperature of 80% of the low-temperature side curing component, subjected to a predetermined test, and then anisotropically conductive at or above the reaction temperature of 80% of the high-temperature side curing component. It describes that the agent is heated and pressurized.

  Patent Document 2 below includes a step of arranging a first circuit member, an anisotropic conductive film containing conductive particles and a photocurable resin, and a second circuit member in this order, and the first circuit member. A step of applying an ultrasonic wave when the circuit member and the second circuit member are press-contacted via an anisotropic conductive film, and after applying the ultrasonic wave, the first circuit member and the second circuit member. And a step of irradiating the anisotropic conductive film with light while bringing the circuit member into contact with the circuit member through the anisotropic conductive film.

JP 2007-262212 A JP 2010-251789 A

  In a liquid crystal display element, a semiconductor chip may be mounted on a glass substrate by a COG method. When obtaining this liquid crystal display element, generally, an anisotropic conductive material containing conductive particles is disposed on a glass substrate. Next, the semiconductor chips are stacked and thermocompression bonded so that the electrodes of the glass substrate and the electrodes of the semiconductor chip face each other. As a result, the anisotropic conductive material is cured, and the electrodes are electrically connected through the conductive particles to obtain a liquid crystal display element.

  In recent years, in a liquid crystal display element, a narrow frame of a liquid crystal panel and a thin glass substrate have progressed. For this reason, the liquid crystal display element obtained becomes easy to warp by the heating at the time of obtaining a liquid crystal display element. Further, when the liquid crystal display element is warped, display unevenness is likely to occur. Furthermore, in a liquid crystal display element, thermal degradation may be a big problem.

  For example, in the Example of patent document 1, in order to harden the high temperature side hardening component of anisotropic conductive adhesive, it heats to 130-170 degreeC. When a liquid crystal display element is manufactured by such a manufacturing method of a connection structure described in Patent Document 1, the liquid crystal display element is warped or thermally deteriorated because it is heated to a temperature of 130 ° C. or higher.

  In Patent Document 2, after applying an ultrasonic wave, the first circuit member and the second circuit member are pressed against each other through the anisotropic conductive film, and light is applied to the anisotropic conductive film. Is being irradiated. However, heating is not performed in this step. For this reason, in the obtained connection structure, there exists a problem that each layer does not fully adhere | attach but it is easy to produce peeling. For this reason, in the obtained connection structure, connection resistance may become high under a reliability test.

  An object of the present invention is to provide a method of manufacturing a liquid crystal display element that can obtain a liquid crystal display element with little warpage, thermal degradation, and high connection reliability. Moreover, the objective of this invention is providing the joining material used for the manufacturing method of the said liquid crystal display element.

  According to a wide aspect of the present invention, there is provided a method for manufacturing a liquid crystal display element in which a substrate having a first electrode on its surface and a semiconductor chip having a second electrode on its surface are connected. A step of disposing a bonding material layer on a surface of a substrate having a surface of the conductive material layer using a bonding material including a curable component and a curing retarder; and on a surface opposite to the substrate side of the conductive material layer. By placing a semiconductor chip having a second electrode on the surface and performing temporary pressure bonding, and before temporary pressure bonding, at the time of temporary pressure bonding or before final pressure bonding after temporary pressure bonding, light is applied to the bonding material layer. To obtain a laminate in which the substrate, the bonding material layer, and the semiconductor chip are temporarily press-bonded, and without heating the laminate to a temperature exceeding 120 ° C. By heating to a temperature of not lower than 120 ° C. and not higher than 120 ° C. A method of manufacturing a liquid crystal display device is provided, comprising: curing a composite material layer to form a cured product layer, and obtaining a liquid crystal display device in which the substrate, the cured product layer, and the semiconductor chip are permanently bonded. Is done.

  In a specific aspect of the method for producing a liquid crystal display element according to the present invention, the bonding material includes a curable compound that can be cured by light irradiation, a photocationic polymerization initiator, and the curing retarder, A curable compound curable by light irradiation contains a polymer having a glycidyl ether group and a monomer having a glycidyl ether group.

  According to a wide aspect of the present invention, there is provided a bonding material used in the above-described method for manufacturing a liquid crystal display element, comprising a curable compound that can be cured by light irradiation, a photocationic polymerization initiator, and a curing retarder. In addition, a bonding material is provided in which the curable compound curable by irradiation with light contains a polymer having a glycidyl ether group and a monomer having a glycidyl ether group.

  In the method for manufacturing a liquid crystal display element according to the present invention, a step of disposing a bonding material layer on the surface of the substrate having the first electrode on the surface using a bonding material containing a curable component and a curing retarder; The semiconductor chip having the second electrode on the surface thereof is disposed on the surface opposite to the substrate side of the bonding material layer, and is temporarily bonded. Alternatively, before the final pressure bonding after the temporary pressure bonding, the step of obtaining a laminated body in which the substrate, the bonding material layer, and the semiconductor chip are temporarily pressure bonded by irradiating the bonding material layer with light; and Without heating to a temperature exceeding 120 ° C., the laminate is heated to a temperature of 80 ° C. or higher and 120 ° C. or lower, and is subjected to main pressure bonding to cure the bonding material layer to form a cured product layer. Liquid crystal in which the substrate, the cured product layer, and the semiconductor chip are finally bonded. Because and a step of obtaining a 示素Ko can warp less, to obtain a liquid crystal display device thermal degradation is suppressed.

FIG. 1 is a cross-sectional view schematically showing an example of a liquid crystal display element obtained by a method for manufacturing a liquid crystal display element according to an embodiment of the present invention. 2A to 2C are schematic perspective views for explaining each step of the method for manufacturing the liquid crystal display element according to the embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a modification of the liquid crystal display element shown in FIG. FIG. 4 is a cross-sectional view showing an example of conductive particles.

  Hereinafter, the present invention will be described in detail.

  The liquid crystal display element according to the present invention is a method for manufacturing a liquid crystal display element in which a substrate having a first electrode on its surface and a semiconductor chip having a second electrode on its surface are connected. In the method of manufacturing the liquid crystal display element, the first electrode and the second electrode are brought into direct contact with each other, or conductive particles are disposed between the first electrode and the second electrode. Thus, the first electrode and the second electrode can be electrically connected.

  In the method for manufacturing a liquid crystal display element according to the present invention, a step of disposing a bonding material layer on the surface of the substrate having the first electrode on the surface using a bonding material containing a curable component and a curing retarder; The semiconductor chip having the second electrode on the surface thereof is disposed on the surface opposite to the substrate side of the bonding material layer, and is temporarily bonded. Alternatively, before the final pressure bonding after the temporary pressure bonding, the step of obtaining a stacked body in which the substrate, the conductive material layer, and the semiconductor chip are temporarily pressure bonded by irradiating the conductive material layer with light; and Without heating to a temperature exceeding 120 ° C., the laminate is heated to a temperature of 80 ° C. or more and 120 ° C. or less, and by performing main pressure bonding, the conductive material layer is cured to form a cured product layer, Liquid crystal in which the substrate, the cured product layer, and the semiconductor chip are finally bonded. And a step of obtaining a 示素Ko.

  In the present invention, since the above-described configuration is provided, it is possible to obtain a liquid crystal display element with less warpage, reduced thermal degradation, and high connection reliability. In particular, since the laminated body is not heated to a temperature exceeding 120 ° C., warpage of the obtained liquid crystal display element can be effectively suppressed, and thermal deterioration of the liquid crystal display element can be sufficiently suppressed. Further, even when the obtained liquid crystal display element is used for a long time and exposed to high temperature or high humidity, the connection resistance hardly increases. In addition, since the bonding material layer is irradiated with light before temporary pressing, at the time of temporary pressing, or before final pressing after temporary pressing, it is possible to shorten the main pressing time for sufficiently bonding the layers. . Further, since the bonding material layer is irradiated with light to activate the curing of the bonding material layer, the layers are sufficiently bonded after heat curing, and peeling is unlikely to occur. Further, even when the liquid crystal display element is slightly warped, it is possible to suppress the separation between the layers. Moreover, since the curvature of a liquid crystal display element can be suppressed, the display nonuniformity of a liquid crystal display element can be suppressed.

  In the present invention, since warpage and thermal deterioration can be effectively suppressed, it is possible to cope with narrowing and thinning of the frame of the liquid crystal display element, the substrate and the semiconductor chip.

  Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings.

(Liquid crystal display element)
FIG. 1 is a cross-sectional view schematically showing an example of a liquid crystal display element obtained by a method for manufacturing a liquid crystal display element according to an embodiment of the present invention.

  A liquid crystal display element 1 shown in FIG. 1 includes a substrate 2, a semiconductor chip 4, and a cured product layer 3 that connects the substrate 2 and the semiconductor chip 4. The cured product layer 3 is formed by curing a bonding material including a curable component and the conductive particles 5.

  The substrate 2 has a plurality of first electrodes 2a on the surface (upper surface). The semiconductor chip 4 has a plurality of second electrodes 4a on the surface (lower surface). The first electrode 2 a and the second electrode 4 a are electrically connected by one or a plurality of conductive particles 5.

  FIG. 3 is a cross-sectional view schematically showing a modification of the liquid crystal display element shown in FIG.

  The liquid crystal display element 11 illustrated in FIG. 3 includes a substrate 12, a semiconductor chip 14, and a cured product layer 13 that connects the substrate 12 and the semiconductor chip 14. The cured product layer 13 is formed by curing a bonding material that includes a curable component and does not include conductive particles.

  The substrate 12 has a plurality of first electrodes 12a on the surface (upper surface). The semiconductor chip 14 has a plurality of second electrodes 14a on the surface (lower surface). The first electrode 12a and the second electrode 14a are, for example, bump electrodes. The first electrode 12a and the second electrode 14a are electrically connected to each other without being in contact with conductive particles. Therefore, the substrate 12 and the semiconductor chip 14 are electrically connected.

  The liquid crystal display element 1 shown in FIG. 1 can be obtained through the steps shown in FIGS. 2A to 2C, for example, as follows.

  As shown in FIG. 2A, a substrate 2 having a first electrode 2a on the surface is prepared. Next, the bonding material layer 3 </ b> A is disposed on the surface of the substrate 2 using a bonding material containing a curable component and a plurality of conductive particles 5 (not shown) (first step). At this time, it is preferable that one or a plurality of conductive particles 5 be disposed on the first electrode 2a. Here, the bonding material is applied using the dispenser 21.

  In the first step, it is preferable to apply the bonding material using a dispenser. In application | coating by a dispenser, a joining material can be arrange | positioned to a predetermined area | region with high precision.

  Next, the semiconductor chip 4 having the second electrode 4a on the surface thereof is disposed on the surface opposite to the substrate 2 side of the bonding material layer 3A, and temporary pressure bonding is performed. At this time, the first electrode 2a and the second electrode 4a are opposed to each other. Further, the light is irradiated to the bonding material layer 3A before the temporary pressure bonding, at the time of the temporary pressure bonding, or before the main pressure bonding after the temporary pressure bonding. As shown in FIG. 2B, a laminate 11 is obtained in which the substrate 2, the bonding material layer 3A, and the semiconductor chip 4 are temporarily bonded (second step). Here, in order to perform temporary pressure bonding, the temporary pressure bonding member 22 is lowered. In addition, the light irradiation device 23 irradiates the bonding material layer 3 </ b> A with light from the lower side to the upper side of the substrate 2. The substrate 2 is preferably a transparent substrate, and is preferably a glass substrate. If the substrate 2 is not transparent, light may be irradiated from above the bonding material layer 3A.

  In the second step, the light irradiation may be performed before temporary pressure bonding, may be performed at the time of temporary pressure bonding, or may be performed before the main pressure bonding after temporary pressure bonding. For example, light transmitted through the substrate can be guided to the bonding material layer by irradiating the bonding material layer with light from the surface side opposite to the bonding material layer of the substrate.

In order to effectively advance the photocuring of the bonding material layer, the integrated light amount when irradiating with light is preferably 50 mJ / cm ² or more, more preferably 100 mJ / cm ² or more, preferably 2000 mJ / cm ² or less, More preferably, it is 1000 mJ / cm ² or less. When the integrated light quantity is not less than the above lower limit and not more than the above upper limit, the bonding material layer is more efficiently cured.

  The time from the irradiation of light to the final pressing is preferably 60 minutes or less, more preferably 10 minutes or less.

  The light source used when irradiating light is not specifically limited. Examples of the light source include a light source having a sufficient light emission distribution at a wavelength of 420 nm or less. Specific examples of the light source include, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, and an LED lamp.

  In the second step, the pressure during temporary pressure bonding is preferably 0.1 MPa or more, more preferably 0.3 MPa or more, preferably 3 MPa or less, more preferably 5 MPa or less. When the pressure at the time of the temporary pressure bonding is not less than the above lower limit and not more than the above upper limit, a laminate that has been preliminarily pressure bonded can be obtained.

  Next, without heating the laminated body 11 to a temperature exceeding 120 ° C., the laminated body 11 is heated to a temperature of 80 ° C. or higher and 120 ° C. or lower, and the main bonding is performed to cure the bonding material layer 3A. A cured product layer 3 is formed. As shown in FIG.2 (c), the liquid crystal display element 1 to which the board | substrate 2, the hardened | cured material layer 3, and the semiconductor chip 4 were press-bonded is obtained (3rd process). Here, in order to perform the main press bonding, the main press bonding member 24 is lowered.

  In the third step, the heating temperature for heating the laminate is 80 ° C. or higher and 120 ° C. or lower. The heating temperature is preferably 90 ° C. or higher, more preferably 110 ° C. or lower. As the heating temperature is lower, the warpage and thermal deterioration of the liquid crystal display element are further suppressed.

  In the third step, the heating time is preferably 1 second or longer, more preferably 3 seconds or longer, preferably 20 seconds or shorter, more preferably 10 seconds or shorter. When the heating time is not less than the lower limit, the bonding material layer is sufficiently cured. When the heating time is not more than the above upper limit, warpage and thermal deterioration of the liquid crystal display element are further suppressed.

  In the third step, the pressure during the main press bonding is preferably 1 MPa or more, more preferably 5 MPa or more, preferably 80 MPa or less, more preferably 60 MPa or less per electrode area of the semiconductor chip. When the pressure at the time of the main press-bonding is not less than the above lower limit and not more than the above upper limit, a liquid crystal display element that is satisfactorily press-bonded can be obtained. Further, when the bonding material includes conductive particles, the first and second electrodes are electrically connected to each other by compressing the conductive particles with the first electrode and the second electrode by pressurization during the main press bonding. The contact area with the conductive particles increases. For this reason, conduction reliability increases. By compressing the conductive particles, even if the distance between the first and second electrodes increases, the particle diameter of the conductive particles increases so as to follow the expansion.

  The electrode width (the first electrode width and the second electrode width) is preferably 5 μm or more, more preferably 10 μm or more, preferably 3000 μm or less, more preferably 2000 μm or less. The inter-electrode width (the first inter-electrode width and the second inter-electrode width) is preferably 3 μm or more, more preferably 10 μm or more, preferably 3000 μm or less, more preferably 2000 μm or less. Further, L / S (line / space) as electrode width / interelectrode width is preferably 5 μm / 5 μm or more, more preferably 10 μm / 10 μm or more, preferably 3000 μm / 3000 μm or less, more preferably 2000 μm / 2000 μm or less. is there.

  The bonding material includes a curable component and a curing retardant. The bonding material is a bonding material that can be cured by light irradiation. The bonding material is preferably a bonding material that can be cured by heating after light irradiation. The bonding material preferably contains a curable compound (curable component) that can be cured by light irradiation and a photocationic polymerization initiator (curable component).

  The viscosity of the bonding material at 30 ° C. is preferably 10 Pa · s or more, more preferably 50 Pa · s or more, preferably 3000 Pa · s or less, more preferably 2000 Pa · s or less. The viscosity is measured using an E-type viscometer (Rotor No. 7 manufactured by Toki Sangyo Co., Ltd.) under conditions of 30 ° C. and a rotation speed of 2.5 rpm. Specific examples of the E-type viscometer include “TV-35” manufactured by Toki Sangyo Co., Ltd.

  Hereinafter, the detail of each component used suitably for the said joining material is demonstrated.

(Curable compound curable by light irradiation)
The curable compound that can be cured by the light irradiation is not particularly limited. Conventionally known curable compounds can be used as the curable compound that can be cured by the light irradiation. As for the curable compound which can be hardened | cured by irradiation of the said light, only 1 type may be used and 2 or more types may be used together.

  Examples of the curable compound that can be cured by the light irradiation include a cationic photopolymerizable compound. The photocationically polymerizable compound is not particularly limited as long as it is a compound having at least one photocationically polymerizable functional group.

  The photocationically polymerizable functional group is not particularly limited, and examples thereof include a group containing an epoxy group such as a glycidyl ether group and an alicyclic epoxy group, an oxetanyl group, a hydroxyl group, a vinyl ether group, an episulfide group, and an ethyleneimine group. It is done.

  From the viewpoint of increasing the storage stability of the bonding material and further suppressing the warpage of the liquid crystal display element, the curable compound that can be cured by irradiation with light includes a polymer having a glycidyl ether group and a glycidyl ether group. It is preferable to contain the monomer which has.

  The weight average molecular weight of the polymer is preferably 4000 or more, more preferably 8000 or more, preferably 30000 or less, more preferably 20000 or less. When the weight average molecular weight is not less than the above lower limit and not more than the above upper limit, the photocurability of the bonding material is further improved. The weight average molecular weight of the polymer indicates a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

  In 100% by weight of the conductive material, the content of the curable compound curable by irradiation with light is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, preferably 20% by weight or less. More preferably, it is 10% by weight or less.

  The content of the polymer having a glycidyl ether group is preferably 10% by weight or more, more preferably 20% by weight or more, preferably 80% by weight or less in 100% by weight of the curable compound curable by light irradiation. More preferably, it is 70 weight% or less. In 100% by weight of the curable compound curable by light irradiation, the content of the monomer having a glycidyl ether group is preferably 10% by weight or more, more preferably 20% by weight or more, preferably 80% by weight or less. More preferably, it is 70% by weight or less. When each content of the polymer having a glycidyl ether group and the monomer having a glycidyl ether group is not less than the above lower limit and not more than the above upper limit, warpage of the liquid crystal display element is further suppressed.

(Photocationic polymerization initiator)
The above cationic photopolymerization initiator generates cations when irradiated with light. The bonding material layer is preferably photocured by the action of the photocationic polymerization initiator. As the photocationic polymerization initiator, iodonium salts and sulfonium salts are preferably used. As a commercial item of the said photocationic polymerization initiator, Adeka optomer SP-150, Adeka optomer SP-170, Adeka optomer SP-171 (above, the product made by ADEKA), UVE-1014 (made by General Electronics Co., Ltd.), And CD-1012 (manufactured by Sartomer).

Preferable examples of the anionic portion of the cationic photopolymerization initiator include PF ₆ , BF ₄ , and B (C ₆ F ₅ ) ₄ .

  Other specific examples of the cationic photopolymerization initiator include 2-butenyldimethylsulfonium tetrakis (pentafluorophenyl) borate, 2-butenyldimethylsulfonium tetrafluoroborate, 2-butenyldimethylsulfate. Phonium hexafluorophosphate, 2-butenyltetramethylenesulfonium tetrakis (pentafluorophenyl) borate, 2-butenyltetramethylenesulfonium tetrafluoroborate, 2-butenyltetramethylenesulfonium hexafluorophosphate, 3 -Methyl-2-butenyldimethylsulfonium tetrakis (pentafluorophenyl) borate, 3-methyl-2-butenyldimethylsulfonium tetrafluoroborate, 3-methyl-2-butenyldimethyls Phonium hexafluorophosphate, 3-methyl-2-butenyltetramethylenesulfonium tetrakis (pentafluorophenyl) borate, 3-methyl-2-butenyltetramethylenesulfonium tetrafluoroborate, 3-methyl-2- Butenyltetramethylenesulfonium hexafluorophosphate, 4-hydroxyphenylcinnamylmethylsulfonium tetrakis (pentafluorophenyl) borate, 4-hydroxyphenylcinnamylmethylsulfonium tetrafluoroborate, 4-hydroxyphenylcinnamylmethyl Sulfonium hexafluorophosphate, α-naphthylmethyltetramethylenesulfonium tetrakis (pentafluorophenyl) borate, α-naphthylmethyltetramethyl Sulfonium tetrafluoroborate, α-naphthylmethyltetramethylenesulfonium hexafluorophosphate, cinnamyldimethylsulfonium tetrakis (pentafluorophenyl) borate, cinnamyldimethylsulfonium tetrafluoroborate, cinnamyldimethylsulfonium Hexafluorophosphate, cinnamyltetramethylenesulfonium tetrakis (pentafluorophenyl) borate, cinnamyltetramethylenesulfonium tetrafluoroborate, cinnamyltetramethylenesulfonium hexafluorophosphate, biphenylmethyldimethylsulfonium tetrakis (penta Fluorophenyl) borate, biphenylmethyldimethylsulfonium tetrafluoroborate, Biphenylmethyldimethylsulfonium hexafluorophosphate, biphenylmethyltetramethylenesulfonium tetrakis (pentafluorophenyl) borate, biphenylmethyltetramethylenesulfonium tetrafluoroborate, biphenylmethyltetramethylenesulfonium hexafluorophosphate, phenylmethyldimethyl Sulfonium tetrakis (pentafluorophenyl) borate, phenylmethyldimethylsulfonium tetrafluoroborate, phenylmethyldimethylsulfonium hexafluorophosphate, phenylmethyltetramethylenesulfonium tetrakis (pentafluorophenyl) borate, phenylmethyltetramethylene Sulfonium tetrafluoroborate, phenyl Rutetramethylenesulfonium hexafluorophosphate, fluorenylmethyldimethylsulfonium tetrakis (pentafluorophenyl) borate, fluorenylmethyldimethylsulfonium tetrafluoroborate, fluorenylmethyldimethylsulfonium hexafluorophosphate, Examples include fluorenylmethyltetramethylenesulfonium tetrakis (pentafluorophenyl) borate, fluorenylmethyltetramethylenesulfonium tetrafluoroborate, and fluorenylmethyltetramethylenesulfonium hexafluorophosphate.

  The cationic photopolymerization initiator preferably releases inorganic acid ions upon irradiation with light, or releases organic acid ions containing boron atoms upon irradiation with light. The photocationic polymerization initiator is preferably a component that releases inorganic acid ions when irradiated with light, and is also preferably a component that releases organic acid ions containing boron atoms when irradiated with light.

The photocationic polymerization initiator that releases inorganic acid ions upon irradiation with light is preferably a compound having SbF ^6- or PF ^6- as an anion moiety. The photocationic polymerization initiator is preferably a compound having SbF ⁶⁻ as the anion moiety, and is preferably a compound having PF ⁶⁻ as the anion moiety.

Anionic portion of the cationic photopolymerization initiator is _{B (C 6 X 5) 4} - is preferably represented by. The photocationic polymerization initiator that releases an organic acid ion containing a boron atom is preferably a compound having an anion moiety represented by the following formula (1).

  In the above formula (1), X represents a halogen atom. X in the formula (1) is preferably a chlorine atom, a bromine atom or a fluorine atom, and more preferably a fluorine atom.

Anionic portion of the cationic photopolymerization initiator is _{B (C 6 F 5) 4} - is preferably represented by. As for the photocationic polymerization initiator which discharge | releases the said organic acid ion containing a boron atom, it is more preferable that it is a compound which has an anion part represented by following formula (1A).

  The type of the cationic photopolymerization initiator may be an ionic photoacid generating type or a nonionic photoacid generating type. The cationic photopolymerization initiator is preferably an antimony complex, a salt having phosphorus hexafluoride ion, or a salt represented by the following formula (2).

  In the above formula (2), n represents an integer of 1 to 12, m represents an integer of 1 to 5, and Rf is a fluoroalkyl group in which all or part of the hydrogen atoms of the alkyl group are substituted with fluorine atoms. Represents.

  The antimony complex is not particularly limited, but is preferably a sulfonium salt. Examples of the sulfonium salt that is the antimony complex include tetraphenyl (diphenyl sulfide-4,4′-diyl) bissulfonium di (antimony hexafluoride), tetra (4-methoxyphenyl) [diphenyl sulfide-4,4 ′. -Diyl] bissulfonium di (antimony hexafluoride), diphenyl (4-phenylthiophenyl) sulfonium hexamonium fluoride, and di (4-methoxyphenyl) [4-phenylthiophenyl] sulfonium hexamonium hexafluoride Etc.

  As a commercial item of the said antimony complex, Adeka optomer SP-170 (made by ADEKA) etc. are mentioned, for example.

  As a commercial item of the salt which has the said hexafluoride phosphorus ion, WPI-113 (made by Wako Pure Chemical Industries), CPI-100P (made by San Apro), etc. are mentioned, for example.

  Content of the said photocationic polymerization initiator is not specifically limited. The content of the cationic photopolymerization initiator is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and still more preferably with respect to 100 parts by weight of the curable compound curable by light irradiation. Is 1 part by weight or more, preferably 10 parts by weight or less, more preferably 8 parts by weight or less, and still more preferably 6 parts by weight or less. When the content of the cationic photopolymerization initiator with respect to the curable compound that can be cured by the light irradiation is not less than the lower limit and not more than the upper limit, the bonding material is sufficiently cured.

(Curing retarder)
The bonding material includes a curing retarder. The curing retarder has a property of lowering the curing rate of the bonding material containing the curing retarder than the bonding material not containing the curing retarder. As for the said hardening retarder, only 1 type may be used and 2 or more types may be used together.

  It does not specifically limit as said hardening retarder, A polyether compound etc. are mentioned. It does not specifically limit as said polyether compound, Polyethylene glycol, polypropylene glycol, polytetramethylene glycol, a crown ether compound, etc. are mentioned. Of these, crown ether compounds are preferred.

  The crown ether compound is not particularly limited, and examples thereof include 12-crown-4, 15-crown-5, 18-crown-6, 24-crown-8, and compounds represented by the following formula (12). .

  In said formula (12), R1-R12 represents a hydrogen atom or a C1-C20 substituted or unsubstituted alkyl group, respectively. However, at least one of R1 to R12 represents an alkyl group having 1 to 20 carbon atoms. The substituted or unsubstituted alkyl group is one or more functional groups selected from the group consisting of an alkoxyl group having 1 to 20 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, and a carboxylic acid alkyl ester group having 1 to 20 carbon atoms. It may be substituted with a group, and adjacent Rn and Rn + 1 (where n represents an even number of 1 to 12) may together form a cyclic alkyl skeleton. The C1-C20 alkoxyl group may be linear or branched.

  Of the compounds represented by the formula (12), a compound having at least one cyclohexyl group is preferable. The presence of the cyclohexyl group stabilizes the skeleton of the crown ether and increases the delay effect.

  Specific examples of the compound having a cyclohexyl group and represented by the above formula (12) include a compound represented by the following formula (12A).

  The compound represented by the chemical formula (12A) has two cyclohexyl groups at positions that are axisymmetric with respect to a line passing through the center of the 18-crown-6-ether molecule. For this reason, it is considered that the delay effect is enhanced without causing distortion or the like in the skeleton of the 18-crown-6-ether molecule.

  The content of the curing retarder is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, preferably 5 parts by weight with respect to 100 parts by weight of the curable compound that can be cured by the light irradiation. Below, more preferably 3 parts by weight or less. When the content of the curing retarder is not less than the above lower limit and not more than the above upper limit, the curing rate of the bonding material becomes even more appropriate.

(Conductive particles)
The bonding material preferably contains conductive particles. The said electroconductive particle should just have an electroconductive part on the electroconductive surface. The conductive part is preferably a conductive layer. As shown in a sectional view of an example of the conductive particles in FIG. 4, the conductive particles 31 may include base material particles 32 and a conductive layer 33 disposed on the surface of the base material particles 32. . The conductive particles may be metal particles whose entirety is a conductive portion. Among these, from the viewpoint of reducing the cost and increasing the flexibility of the conductive particles to increase the conduction reliability between the electrodes, the base particles and the conductive material disposed on the surface of the base particles are used. Conductive particles having a layer are preferred.

  Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles excluding metal particles, and are preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles.

  The substrate particles are preferably resin particles formed of a resin. When connecting between electrodes using electroconductive particle, after arrange | positioning electroconductive particle between electrodes, electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles, the conductive particles are likely to be deformed during the pressure bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes still higher.

  Examples of the resin for forming the resin particles include polyolefin resin, acrylic resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, and polyphenylene. Examples thereof include oxide, polyacetal, polyimide, polyamideimide, polyetheretherketone, polyethersulfone, divinylbenzene polymer, and divinylbenzene copolymer. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid ester copolymer. Since the hardness of the resin particles can be easily controlled within a suitable range, the resin for forming the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. It is preferably a coalescence.

  Examples of the inorganic substance for forming the inorganic particles include silica and carbon black. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

  When the substrate particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium.

  The metal for forming the conductive part is not particularly limited. Furthermore, in the case where the conductive particles are metal particles that are conductive parts as a whole, the metal for forming the metal particles is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and these. And the like. Examples of the metal include tin-doped indium oxide (ITO) and solder. Especially, since the connection resistance between electrodes becomes still lower, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is preferable.

  The conductive layer may be formed of a single layer. The conductive layer may be formed of a plurality of layers. That is, the conductive layer may have a stacked structure of two or more layers. When the conductive layer is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver, and is a gold layer. Is more preferable. When the outermost layer is these preferred conductive layers, the connection resistance between the electrodes is further reduced. Moreover, when the outermost layer is a gold layer, the corrosion resistance is further enhanced.

  The method for forming the conductive layer on the surface of the substrate particles is not particularly limited. As a method for forming the conductive layer, for example, a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating the surface of base particles with metal powder or a paste containing metal powder and a binder Etc. Especially, since formation of a conductive layer is simple, the method by electroless plating is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering.

  The average particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 500 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, and particularly preferably 70 μm or less. When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrode becomes sufficiently large and the conductive Aggregated conductive particles are less likely to be formed when the layer is formed. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the base material particles.

  The “average particle size” of the conductive particles indicates a number average particle size. The average particle diameter of the conductive particles can be obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  The thickness of the conductive layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. When the thickness of the conductive layer is not less than the above lower limit and not more than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed when connecting the electrodes. .

  When the conductive layer is formed of a plurality of layers, the thickness of the outermost conductive layer is preferably 0.001 μm or more, more preferably the thickness of the gold layer when the outermost layer is a gold layer. It is 0.01 μm or more, preferably 0.5 μm or less, more preferably 0.1 μm or less. When the thickness of the outermost conductive layer is not less than the above lower limit and not more than the above upper limit, the coating with the outermost conductive layer becomes uniform, corrosion resistance is sufficiently high, and the connection resistance between the electrodes is sufficiently high. Lower. Further, the thinner the gold layer when the outermost layer is a gold layer, the lower the cost.

  The thickness of the conductive layer can be measured, for example, by observing a cross section of the conductive particles or the conductive particles using a transmission electron microscope (TEM).

  From the viewpoint of increasing the contact area between the electrode and the conductive particle and further enhancing the conduction reliability between the electrodes, the conductive particle is composed of a resin particle and a conductive layer (on the surface of the resin particle ( First conductive layer).

  The content of the conductive particles is not particularly limited. In 100% by weight of the bonding material, the content of the conductive particles is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, still more preferably 1% by weight or more, preferably 40% by weight or less. More preferably, it is 30 weight% or less, More preferably, it is 19 weight% or less. A conductive particle can be easily arrange | positioned between the upper and lower electrodes which should be connected as content of the said electroconductive particle is more than the said minimum and below the said upper limit. Furthermore, it becomes difficult to electrically connect adjacent electrodes that should not be connected via a plurality of conductive particles. That is, a short circuit between adjacent electrodes can be further prevented.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to the following examples.

(Synthesis Example 1) Polymer Synthesis 72 parts by weight of bisphenol F, 100 parts by weight of 1,6-hexanediol diglycidyl ether and 1 part by weight of triphenylphosphine were placed in a three-necked flask and dissolved at 150 ° C. Thereafter, an addition polymerization reaction was carried out at 180 ° C. for 7 hours to obtain an epoxy compound (polymer).

  After confirming that the addition polymerization reaction has progressed, the epoxy compound has in its main chain a structural unit in which a skeleton derived from bisphenol F and a skeleton derived from 1,6-hexanediol diglycidyl ether are bonded, and 1 , 6-hexanediol diglycidyl ether was confirmed to have an epoxy group at both ends.

  The resulting polymer had a weight average molecular weight of 8,000.

  In addition, the weight average molecular weight of a polymer shows the weight average molecular weight in polystyrene conversion measured by gel permeation chromatography (GPC).

Example 1
(1) Preparation of Bonding Material To 50 parts by weight of the epoxy compound obtained in Synthesis Example 1 and 50 parts by weight of bisphenol A epoxy resin (“EXA-850CRP” manufactured by DIC), a photocationic polymerization initiator (manufactured by ADEKA “ 3 parts by weight of Adekaoptomer SP-170 "), 0.2 parts by weight of 18-crown-6, and 17 parts by weight of conductive particles A (average particle size 3 μm) were added, and 2000 rpm using a planetary stirrer. Was stirred for 5 minutes to obtain a bonding material (conductive paste).

  The conductive particles A used are conductive particles having a conductive layer in which a nickel plating layer is formed on the surface of divinylbenzene resin particles and a gold plating layer is formed on the surface of the nickel plating layer. is there.

(2) Production of Connection Structure A glass substrate (thickness 300 μm) having an L / S of 20 μm / 20 μm and a Mo / Al / Mo electrode pattern having 998 electrodes formed on the upper surface was prepared. Further, a semiconductor chip (18 mm × 1.1 mm) having a gold electrode pattern on the lower surface with L / S of 20 μm / 20 μm, 998 electrodes, and bump height of 15 μm was prepared.

On the glass substrate, the bonding material immediately after fabrication was applied using a dispenser so as to have a width of 2.3 mm and a thickness of 30 μm, and after forming a bonding material layer, 365 nm ultraviolet light was irradiated at a light irradiation intensity of 700 mW / Irradiation was performed for 3 seconds so as to be cm ² .

  Next, the semiconductor chip was stacked on the bonding material layer so that the electrodes were opposed to each other and connected. Thereafter, the temperature of the heating head is adjusted so that the temperature of the bonding material layer becomes 120 ° C. (final pressure bonding temperature), the heating head is placed on the upper surface of the semiconductor chip, and the bonding material is cured at 120 ° C. for 10 seconds to be cured. Layers were formed to obtain a connection structure.

(Example 2)
A connection structure was obtained in the same manner as in Example 1 except that the semiconductor chip was laminated on the bonding material layer and at the same time ultraviolet rays were irradiated from the back surface of the glass substrate.

Example 3
A connection structure was obtained in the same manner as in Example 1 except that ultraviolet rays were irradiated from the back surface of the glass substrate after the semiconductor chip was laminated on the bonding material layer.

Example 4
A connection structure was obtained in the same manner as in Example 1 except that the main pressure bonding temperature was set to 80 ° C.

(Example 5)
A connection structure was obtained in the same manner as in Example 2 except that the main pressure bonding temperature was set to 80 ° C.

(Example 6)
A connection structure was obtained in the same manner as in Example 3 except that the main pressure bonding temperature was set to 80 ° C.

(Example 7)
A connection structure was obtained in the same manner as in Example 3 except that the conductive particles A were not used.

(Example 8)
A connection structure was obtained in the same manner as in Example 6 except that the conductive particles A were not used.

(Comparative Example 1)
A connection structure was obtained in the same manner as in Example 1 except that 18-crown-6 was not used.

(Comparative Example 2)
A connection structure was obtained in the same manner as in Example 2 except that 18-crown-6 was not used.

(Comparative Example 3)
A connection structure was obtained in the same manner as in Example 3 except that 18-crown-6 was not used.

(Comparative Example 4)
A connection structure was obtained in the same manner as in Example 3 except that the main pressure bonding temperature was set to 60 ° C.

(Comparative Example 5)
Except for adding 15 parts by weight of a thermosetting agent (imidazole compound, “2MZ-H” manufactured by Shikoku Kasei Kogyo Co., Ltd.) without adding a photocationic polymerization initiator (“ADEKA OPTMER SP-170” manufactured by ADEKA). Obtained a bonding material (conductive paste) in the same manner as in Example 1. Using the obtained bonding material, a connection structure was obtained in the same manner as in Example 1 except that ultraviolet rays were not irradiated.

(Comparative Example 6)
A connection structure was obtained in the same manner as in Comparative Example 5 except that the main pressing temperature was set to 80 ° C.

(Comparative Example 7)
A connection structure was obtained in the same manner as in Comparative Example 5 except that the main pressure bonding temperature was set to 180 ° C.

(Evaluation)
(1) Warpage of Connection Structure The amount of warpage of the semiconductor element of the obtained connection structure (liquid crystal display element) was measured using a shape measurement laser microscope (“VK-X200 series” manufactured by Keyence Corporation). The maximum height displacement from the end of the semiconductor chip to the center was taken as the value of warpage.

(2) Conduction reliability (connection resistance value)
The connection resistance between the upper and lower electrodes of the obtained connection structure was measured by a four-terminal method. The average value of the connection resistance at 40 locations was calculated. Note that the connection resistance can be obtained by measuring the voltage when a constant current is passed from the relationship of voltage = current × resistance. The conduction reliability between the electrodes in the obtained connection structure was determined according to the following criteria.

[Judgment criteria for conduction reliability]
○○: Connection resistance is less than 1.5Ω ○: Connection resistance is 1.5Ω or more and less than 2Ω △: Connection resistance is 3Ω or more and less than 5Ω ×: Connection resistance is 5Ω or more

(3) Connection reliability The obtained connection structure was allowed to stand for 500 hours at 60 ° C. and a relative humidity of 90%. The connection resistance after standing was measured in the same manner as in the above (2) evaluation of conduction reliability. Connection reliability was determined according to the following criteria.

[Connection reliability criteria]
○○: Connection resistance is less than 3Ω ○: Connection resistance is 3Ω or more and less than 5Ω Δ: Connection resistance is 5Ω or more and less than 10Ω ×: Connection resistance is 10Ω or more

(4) Storage stability Viscosity η1 at 25 ° C. of the obtained bonding material was measured using an E-type viscosity measuring device (“VISCOMETER TV-22” manufactured by TOKI SANGYO CO. LTD, cone rotor: No. 7, temperature: 25 )) At 25 ° C. and 2.5 rpm. Next, the bonding material was allowed to stand at 25 ° C. for 168 hours. The viscosity η2 at 25 ° C. of the bonding material after standing was measured in the same manner. Storage stability was determined according to the following criteria.

[Criteria for storage stability]
◯: Ratio of viscosity η2 to viscosity η1 is less than 1.2 ○: Ratio of viscosity η2 to viscosity η1 is 1.2 or more and less than 1.4 Δ: Ratio of viscosity η2 to viscosity η1 is 1.4 or more, 1 Less than 6 x: Ratio of viscosity η2 to viscosity η1 is 1.6 or more

  The results are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 1,11 ... Liquid crystal display element 2,12 ... Board | substrate 2a, 12a ... 1st electrode 3,13 ... Hardened | cured material layer 3A ... Bonding material layer 4,14 ... Semiconductor chip 4a, 14a ... 2nd electrode 5 ... Conductivity Particle 11 ... Laminate 21 ... Dispenser 22 ... Temporary pressure bonding member 23 ... Main pressure bonding member 24 ... Light irradiation device 31 ... Conductive particle 32 ... Base material particle 33 ... Conductive layer

Claims (3)

A method of manufacturing a liquid crystal display element in which a substrate having a first electrode on its surface and a semiconductor chip having a second electrode on its surface are connected,
A step of disposing a bonding material layer on the surface of the substrate having the first electrode on the surface using a bonding material containing a curable component and a curing retarder;
On the surface opposite to the substrate side of the bonding material layer, by placing a semiconductor chip having a second electrode on the surface and performing temporary pressure bonding, and before temporary pressure bonding, Irradiating the bonding material layer with light before the final pressure bonding after the temporary pressure bonding to obtain a laminate in which the substrate, the bonding material layer, and the semiconductor chip are temporarily pressure bonded;
Without heating the laminated body to a temperature exceeding 120 ° C., the laminated body is heated to a temperature of 80 ° C. or higher and 120 ° C. or lower and subjected to main pressure bonding, whereby the bonding material layer is cured and a cured product layer is formed. And a step of obtaining a liquid crystal display element in which the substrate, the cured product layer, and the semiconductor chip are permanently bonded to each other. The bonding material includes a curable compound curable by light irradiation, a cationic photopolymerization initiator, and the curing retardant.
The method for producing a liquid crystal display element according to claim 1, wherein the curable compound curable by light irradiation contains a polymer having a glycidyl ether group and a monomer having a glycidyl ether group. A bonding material used in the method for manufacturing a liquid crystal display element according to claim 1 or 2,
A curable compound curable by light irradiation, a cationic photopolymerization initiator, and a curing retarder;
The bonding material, wherein the curable compound curable by light irradiation contains a polymer having a glycidyl ether group and a monomer having a glycidyl ether group.

Images