JP2007153933A - Bonding method and adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bonding method capable of forming a pattern of an adhesive layer on part of a bonding surface in a high position accuracy and a high thickness accuracy and capable of providing high productivity. <P>SOLUTION: A method for bonding two adhrends 1 and 2 together through parts of their respective opposing bonding surfaces. This method comprises the successive steps of: forming an adhesive layer 3 from an adhesive on the bonding surface of one adherend 1, exposing the adhesive layer 3 to light by irradiation with light through a negative photomask 4 to change the part irradiated with light into a stage B heat-sensitive adhesive layer 5, removing the area not irradiated with light in the light exposure by developing it, and heating the heat-sensitive adhesive layer 5 remaining after the development after contact with the bonding surface of the other adherend 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bonding method used for bonding two adherends in assembling an electronic component, a semiconductor or a device, and an adhesive used for using this bonding method.

  A method of bonding two adherends using a thermosetting resin adhesive is widely used in manufacturing various electronic parts and semiconductors and assembling electronic / electrical devices (for example, Patent Document 1). 5). As described above, many bonding methods are known, but when bonding two adherends, there are cases where an adhesive is present on all of the facing bonding surfaces and bonding to a part of the facing bonding surfaces. An agent may be present. That is, in the latter case, the adhesive is present on a part of the adhesion surface of the adherend by some method and the adhesive is not present on the other part. Often there is a need to create a unique situation. For example, when a metal cover is attached to the cavity portion of an electronic component, it is necessary to apply an adhesive only to the peripheral portion of the cavity portion. Further, in the liquid crystal module, a space for injecting the liquid crystal compound is formed in the central portion by bonding two glass substrates only at the outer peripheral portion.

As described above, the following three methods are mainly used as a method of partially forming the adhesive layer. That is, the first method is to apply a liquid adhesive in a desired shape using a dispenser, and the second method is to print the liquid adhesive through a mask having a desired shape pattern. In addition, the third method is to cut and paste a sheet-like adhesive into a desired shape pattern.
Japanese Patent Laid-Open No. 11-43661 JP-A-3-179765 JP-A-10-279895 JP 2000-265145 A Japanese Patent Laid-Open No. 1-204982

  However, the three methods for partially forming the adhesive layer have the following problems.

  In other words, the adhesive pattern formation method using the dispenser method (the first method) is easy and widely used, but it is necessary to form each pattern one by one. Inferiority / Unable to form a pattern with high positional accuracy / Difficult to control uniform thickness / Limited to low-viscosity liquid adhesives.

  In addition, the adhesive pattern forming method using the printing method (the second method) can form many patterns at a time, so it is excellent in productivity, but in terms of position accuracy and thickness accuracy. In addition to having the same problems as the dispenser method, it requires the properties of a liquid adhesive that can be printed (does not cause sagging or blurring), and the applicable thickness is limited due to the construction method. .

  Further, in the method of cutting and using the last sheet-like adhesive in a desired shape (the third method), cutting with high productivity enables cutting with high productivity, but the pattern shape is complicated or thick. However, in applications where there is not enough, it is difficult to handle in the process of pasting onto the adherend in the next stage, and the productivity is not high. Furthermore, it is difficult to ensure positional accuracy in the attaching process.

  The present invention has been made in view of the above points, and an adhesion method capable of forming a pattern of an adhesive layer on a part of an adhesion surface with high positional accuracy and thickness accuracy and at the same time achieving high productivity. And it aims at providing an adhesive agent.

  The bonding method according to the first aspect of the present invention is a method of bonding two adherends 1 and 2 at a part of the bonding surfaces facing each other, and using an adhesive on the bonding surface of one adherend 1. The adhesive layer 3 is formed, and the adhesive layer 3 is irradiated with light through a negative photomask 4 and exposed to light, so that the portion irradiated with the light is in a B stage state. And a step of removing by developing a portion that was not irradiated with light at the time of exposure, and contacting the adhesive surface of the other adherend 2 with the heat-sensitive adhesive layer 5 remaining after the development. And the step of heating.

  The invention according to claim 2 is characterized in that, in claim 1, the degree of B-staging of the heat-sensitive adhesive layer 5 is adjusted by heat-aging the adhesive layer 3 before developing after exposure. It is what.

  The invention according to claim 3 is characterized in that, in claim 1 or 2, the temperature during exposure is 50 ° C. or less.

  An adhesive according to a fourth aspect of the present invention is an adhesive used for using the bonding method according to any one of the first to third aspects, and is a liquid containing a cationically polymerizable resin and a photocationic polymerization initiator. Or it is a sheet-like thing, It is characterized by the above-mentioned.

  The invention according to claim 5 is characterized in that, in claim 4, the cationically polymerizable resin is a compound having a cyclic structure containing an oxygen atom, and is cured by ring-opening polymerization. .

  The invention according to claim 6 is characterized in that, in claim 5, the compound having a cyclic structure containing an oxygen atom is an epoxy resin.

  The invention according to claim 7 is characterized in that in any one of claims 4 to 6, it contains a thermal cationic polymerization initiator that generates cations by heating.

  The invention according to claim 8 is characterized in that it contains at least one of phenoxy resin, butyral resin, and epoxidized polybutadiene having a hydroxyl group in any one of claims 4 to 7.

  According to the bonding method of the first aspect of the present invention, by using the photolithography method, the pattern of the heat-sensitive adhesive layer in the B stage state is applied to the part of the bonding surface of the adherend with the positional accuracy and the thickness accuracy. In addition, since the heat-sensitive adhesive layer is in a B-stage state, the two adherends can be formed on a part of the adhesive surfaces facing each other. Even in the case of bonding, high adhesion can be obtained.

  According to the invention which concerns on Claim 2, reaction can be advanced to such an extent that it can develop easily, staying at the reaction degree of the grade which can be heat-bonded later.

  According to the invention which concerns on Claim 3, acceleration of the B-stage formation by heat can be suppressed.

  According to the adhesive according to claim 4 of the present invention, it is possible to easily form a B-stage heat-sensitive adhesive layer that does not dissolve in the developer.

  According to the invention which concerns on Claim 5, while being able to obtain favorable sclerosis | hardenability, B-stage-izing of an adhesive bond layer can be controlled easily.

  According to the invention which concerns on Claim 6, while being able to obtain further favorable sclerosis | hardenability, B-stage-izing of an adhesive bond layer can be controlled more easily.

  According to the invention which concerns on Claim 7, the quantity of a cation active species can be increased further in the process of B-staging or heat bonding.

  According to the invention which concerns on Claim 8, the following effects can be acquired.

  That is, in the case of using a phenoxy resin, it is possible to improve the film formability in the varnish coating process when forming the adhesive into a film, and reduce the tackiness of the film after drying, It is possible to impart the effect of reducing the brittleness and exhibiting flexibility, and to impart the effect of reducing pattern chipping during pattern exposure / development after applying a film adhesive. . Moreover, since it has a hydroxyl group in the molecule, it has a chain transfer effect in a cationic curing system and can increase the polymerization rate (curing rate).

  In addition, when using a butyral resin, the curability of the adhesive can be increased, the adhesion to the adherend can be improved, and the tackiness of the dried coating film can be suppressed due to the large molecular weight. The brittleness can be reduced, and when a pattern is formed by development after partial exposure with a mask or the like, it is possible to suppress defects such as cracks and pattern defects during development.

  Even in the case of using an epoxidized polybutadiene having a hydroxyl group, it is possible to exhibit effects such as film-formability, improved curability by the hydroxyl group, and improved developability.

  Embodiments of the present invention will be described below.

  The bonding method according to the present invention is a method of bonding the two adherends 1 and 2 with a part of the bonding surface facing each other. An example of this bonding method is shown in FIG.

  In the steps shown in FIGS. 1A and 1B, first, an adhesive layer 3 is formed on the adhesive surface of one adherend 1 using an adhesive. Here, as one adherend 1, for example, a base plate 6 such as an aluminum plate or FR 4 can be used. Although the case where the base material 6 is used is demonstrated below, this invention is not limited to this. The adhesive is not particularly limited as long as it has negative photosensitivity, can be developed in a B-stage state, and can be thermally bonded. Details of such an adhesive will be described later. Further, the form of the adhesive is not particularly limited, and a liquid or sheet (film) adhesive can be used. In the case of using a liquid adhesive, the adhesive layer 3 can be formed on the surface of the substrate 6 (the surface to be the adhesive surface) by using a spin coating method, a printing method, or the like. On the other hand, when a sheet-like adhesive is used, the adhesive layer 3 can be formed on the surface of the substrate 6 (surface to be an adhesive surface) by using a laminating method or the like. Thus, in the step shown in FIG. 1B, the adhesive layer 3 can be formed on the entire surface to be the bonding surface.

Next, in the step shown in FIG. 1C, the adhesive layer 3 is exposed to light such as ultraviolet rays (indicated by arrows) through a negative photomask 4 having a desired mask pattern. As a result, a chemical reaction occurs in a portion exposed to light, and no reaction occurs in a portion not exposed to light. In this manner, the portion irradiated with light in the adhesive layer 3 is changed to the heat-sensitive adhesive layer 5 in the B stage state. The exposure amount is not particularly limited, but is preferably in the range of 0.1 to 10 J / cm ² .

  Next, in the step shown in FIG. 1D, light is blocked by the negative photomask 4 at the time of the previous exposure, and the portion of the adhesive layer 3 that is not irradiated with light is removed by development. If it does so, the base material 7 with a heat-sensitive adhesive layer as shown in FIG.1 (d) can be obtained. Depending on the presence or absence of the chemical reaction described above, the developer resistance differs between the exposed part and the non-exposed part. Therefore, by selecting an appropriate developer / development condition, as shown in FIG. Only the part of the adhesive layer 3 exposed to light remains as the heat-sensitive adhesive layer 5 in the B stage state, and the other part of the adhesive layer 3 is removed. This series of processes is so-called “photolithography” and is a method that has been used in many fields for a long time. In the present invention, the adhesive layer 3 remaining as a pattern here is in a B-stage state. There are some features.

  Next, when the base material 7 with a heat-sensitive adhesive layer obtained in the step shown in FIG. 1 (d) was cut into a plurality of pieces as shown by broken lines, it was separated into pieces as shown in FIG. 1 (e). The base material 8 can be obtained. In addition, what is necessary is just to perform singulation as needed. When not separated into pieces, the base material 7 with a heat-sensitive adhesive layer can be used as a normal bonding sheet.

  Then, in the last step shown in FIG. 1 (f), the heat-sensitive adhesive layer 5 remaining after development is brought into contact with the adhesive surface of the other adherend 2 and heated. Then, the heat-sensitive adhesive layer 5 shifts from the B-stage state to the C-stage state, so that the two adherends 1 and 2 are partly bonded to each other as shown in FIG. It will be able to adhere. Here, the other adherend 2 is not particularly limited, and for example, a glass plate or the like can be used. In the case shown in FIG. 1 (f), the cavity portion 9 is formed. A base material 10 is used, and the cavity portion 9 is sealed with an individual base material 8 which is one adherend 1. Reference numeral 11 denotes an electronic device provided in the cavity 9.

  If the above-described series of steps are sequentially performed, the following effects can be obtained. That is, since the photolithography method is used, the pattern of the heat-sensitive adhesive layer 5 in the B-stage state can be formed on a part of the adhesion surface of the adherend 1 with high positional accuracy and thickness accuracy. It is possible to obtain high properties. More specifically, since the pattern formation of the heat-sensitive adhesive layer 5 is performed using a photolithography method, high positional accuracy can be obtained, and the pattern formation is performed in a lump. Further, productivity can be increased, and the thickness of the adhesive layer 3 can be determined at an initial stage shown in FIG. Further, since the heat-sensitive adhesive layer 5 is in a B-stage state, even when the two adherends 1 and 2 are bonded to each other at a part of the facing adhesive surface, high adhesion can be obtained. It can be done. Moreover, since the photolithographic method is used, even if the pattern of the heat-sensitive adhesive layer 5 has a complicated shape, it can be easily formed.

  In the present invention, the degree of B-staging of the heat-sensitive adhesive layer 5 can be adjusted by subjecting the adhesive layer 3 to heat aging before development after exposure. That is, the control of advancing the reaction to such an extent that it can be easily developed while keeping the reaction level so that it can be thermally bonded later can be performed by heat aging. The temperature at this time is not particularly limited, but is preferably about 50 to 130 ° C. If it is lower than 50 ° C., there is a possibility that a sufficient change cannot be expected as compared with the degree of reaction due to exposure. There is a possibility that sufficient properties may not be obtained.

  In the present invention, the temperature during exposure (working temperature) is preferably 50 ° C. or lower (the practical lower limit is room temperature). This is because if the temperature at the time of exposure is higher than 50 ° C., not only photoreaction but also acceleration of B-stage formation by heat may occur, which may make control difficult. The exposure time means from the start of exposure to the end of exposure.

  Next, the adhesive which can be used suitably for use of the adhesion | attachment method based on this invention is demonstrated. The adhesive is not particularly limited as long as it can be developed in the B-stage state and can be thermally bonded. For example, a group that undergoes a photodimerization reaction and a thermosetting property. An adhesive having the functions of both reactive groups can be used. When such an adhesive is used, it is possible to use a method in which developability is realized by photodimerization and then adhesion is performed with the other reactive group. Specific examples of such an adhesive include an oligomer having a cinnamic acid terminal as a component that causes a reaction capable of photodimerization, and further, a thermal cationic polymerization initiator and an epoxy resin, or a thermal radical initiator and an acrylic oligomer. And a composition containing a monomer and a monomer at the same time. Other examples include liquid or sheet-like (film-like) adhesives containing a cationically polymerizable resin and a photocationic polymerization initiator. In the present invention, such adhesives are used. Is preferred. By using such an adhesive, it is possible to easily form the heat-sensitive adhesive layer 5 in the B stage state that does not dissolve in the developer.

  Here, examples of the cationically polymerizable resin include an epoxy resin, a vinyl ether resin, an oxetane resin, and a furan resin. However, in terms of curability and control of B-stage formation, the cationically polymerizable resin is It is preferable that the compound has a cyclic structure containing an oxygen atom and is cured by ring-opening polymerization. Specific examples of such cationically polymerizable resins include epoxy resins, oxetane resins, and furan resins. Moreover, it is preferable that the compound which has a cyclic structure containing an oxygen atom is an epoxy resin. Compositions containing acrylic oligomers and monomers containing photoradical initiators that are commonly used in applications that form patterns with light (for dry film and solder resist applications) are suitable for use as adhesives in the present invention. Absent. This is because radicals generated by light are chain-polymerized even at low temperatures, so that it is difficult to control the degree of reactivity that can withstand development and can be thermally bonded.

  The epoxy resin is not particularly limited as long as it has a plurality of epoxy groups in one molecule, and a commercially available liquid epoxy resin or solid epoxy resin can be appropriately used. Specific examples of the epoxy resin include alicyclic epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin having biphenyl skeleton, naphthalene ring-containing epoxy resin, dicyclopentadiene Dicyclopentadiene type epoxy resin having a skeleton, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, bromine-containing epoxy resin, aliphatic epoxy resin, triglycidyl isocyanurate, etc. These can be used alone or in combination of two or more. In addition to the epoxy resin, other cationic polymerizable resins such as an oxetane resin can be used in combination.

The cationic photopolymerization initiator is not particularly limited as long as it generates a Lewis acid or a Bronsted acid by light. Specific examples thereof include PF ₆ ⁻ , AsF ₆ ⁻ as anions. , SbF ₆ ⁻ , SbCl ₆ ²⁻ , BF ₄ ⁻ , SnCl ₆ ⁻ , FeCl ₄ ⁻ , BiCl ₅ ^{2−, and the} like, and as anions, PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , SbCl ₆ ²⁻ , BF ₄ ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , FSO ₃ ⁻ , F ₂ PO ₂ ⁻ , B (C ₆ F ₅ ) ₄ ^{− and the} like, diaryl iodonium salts, triaryl sulfonium salts , triarylselenonium salt, as an ^{_{anion, PF 6 -, AsF 6 -}} , SbF 6 - Jiarukirufu with like Nasylsulfonium salts, dialkyl-4-hydroxyphenylsulfonium salts, and sulfonic acids such as α-hydroxymethylbenzoin sulfonate, N-hydroxyimide sulfonate, α-sulfonyloxy ketone and β-sulfonyloxy ketone An ester, an iron allene compound, a silanol-aluminum complex, o-nitrobenzyl-triphenylsilyl ether, etc. can be mentioned, and only one kind may be used, or a plurality of initiators may be used in combination. Good. Among these cationic photopolymerization initiators, triallylsulfonium salt or diallyl iodonium salt is most preferable because of its cation generation efficiency and stability. In addition, the addition amount of a photocationic polymerization initiator is although it does not specifically limit, It is preferable that it is the range of 0.1-10PHR.

  Photocationic polymerization initiators generate cationically active species efficiently by light irradiation, but unlike radical systems, some heating is required for the cationic polymerization reaction of epoxy resins and the like to proceed due to the generated cations. In the stage where the cation active species are generated at a low temperature, the resin chain reaction does not occur so much, and the degree of the reaction can be easily controlled by the heating temperature and time. As a result of finding out this point by the present inventor, the present invention has been completed.

  Moreover, in this invention, it is preferable to contain the thermal cationic polymerization initiator which generate | occur | produces a cation by heating in addition to the photocationic polymerization initiator for generating a cation by a light irradiation process. Thereby, the amount of cationic active species can be further increased in the B-staging and heat bonding processes. In addition, although the addition amount of a thermal cationic polymerization initiator is not specifically limited, It is preferable that it is the range of 0.1-5 PHR.

  Moreover, in order to generate a cation efficiently by an initiator, a so-called sensitizer can be used in combination. Specific examples include benzophenone, acridine orange, perylene, anthracene, phenothiazine, 2,4-diethylthioxanthone, and the like.

  In the cationic curing system, a chain transfer agent can be used in combination for the purpose of increasing the polymerization rate and preventing unreacted epoxy resin from being left behind. In general, polyfunctional alcohols are used, and examples thereof include ethylene glycol, butanediol, trimethylolpropane triol, pentaerythritol, and polyvinyl alcohol.

  Furthermore, a coupling agent for increasing the adhesive property of the adhesive, for example, various silane coupling agents, titanate coupling agents, and aluminate coupling agents may be used. It is also possible to use additives such as fillers, pigments and dyes as long as they do not inhibit the generation of cations by light irradiation.

  In the present invention, the adhesive preferably contains at least one of phenoxy resin, butyral resin, and epoxidized polybutadiene having a hydroxyl group.

  Here, the phenoxy resin is a polyhydroxy polyether having an epoxy group synthesized from a bisphenol A-type or bisphenol F-type epoxy resin, and commercially available having a weight average molecular weight (Mw) of 40,000 to 60,000. Has been. For example, “Epicoat 1256” (Mw approx. 50,000 for bisphenol A type), “Epicoat 4250”, “Epicoat 4275” (Mw approx. 60,000 for a mixture of bisphenol A type and F type) are available from Japan Epoxy Resin Co., Ltd. In addition, “Phenototo YP-50” (bisphenol A type, Mw of about 60,000) is marketed by Toto Kasei Co., Ltd. Since the phenoxy resin is a thermoplastic resin having a reactive group, it can improve the film formability in the varnish coating process when it is formed into a film, and also reduces the tackiness of the film after drying, It is possible to impart the effect of reducing the brittleness and exhibiting flexibility, and to impart the effect of reducing pattern chipping during pattern exposure / development after applying a film adhesive. . Moreover, since it has a hydroxyl group in the molecule, it has a chain transfer effect in a cationic curing system and can increase the polymerization rate (curing rate).

  A preferable blending ratio of the phenoxy resin is 1 to 10% by weight in the total resin. If it is less than 1% by weight, it will be difficult to exert effects such as good varnish film formability and tackiness suppression, flexibility, and core defect suppression during development, which are the characteristics of blending phenoxy resin. On the contrary, if it exceeds 10% by weight, the thickening of the varnish becomes remarkable, and if the solvent content of the varnish is increased, coating becomes possible, but the amount of solvent used increases and the cost increases. In any case, there is a possibility that the thickness of the wet film is significantly reduced after drying.

  Butyral resin is also sold as an industrial reagent or a chemical experiment reagent, and as an industrial resin, for example, Denka Butyral is sold by Denki Kagaku Kogyo Co., Ltd. In terms of the degree of polymerization of how many monomers are polymerized, those of about 630 to 2400 (about 70,000 to 300,000 when converted to weight average molecular weight) are produced. Since this resin contains a hydroxyl group derived from vinyl alcohol, it can increase the curability of the adhesive by acting as a chain transfer agent for cationic polymerization and improve the adhesion to the adherends 1 and 2. It has a high molecular weight and can suppress the tackiness of the dried coating film and reduce brittleness. When developing and patterning after partial exposure with a mask, etc., cracks and patterns during development It is possible to suppress defects such as chipping.

  A preferable blending amount of the butyral resin is 1 to 30% by weight in the total resin. If the amount is less than 1% by weight, it may be difficult to exhibit the characteristics of blending a butyral resin. Conversely, if the amount exceeds 30% by weight, the varnish will increase in viscosity, and the varnish contains a solvent. If the rate is increased, coating is possible, but there is a risk that the amount of solvent used will increase and the cost will increase, or the thickness of the wet film will decrease significantly after drying. . The molecular weight of the butyral resin is preferably 800 or less (about 100,000 or less in terms of weight average molecular weight) in terms of degree of polymerization. If the degree of polymerization exceeds 800, varnish thickening becomes noticeable, resulting in the disadvantages described above. When the molecular weight is decreased, the effect of improving the tackiness and brittleness of the dried coating film becomes weaker, but the one with the lowest polymerization degree provided in the past by Denki Kagaku Kogyo Co., Ltd. is 300 (converted to the weight average molecular weight) Then, about 30,000), and up to this level, a sufficient effect can be maintained. In addition, no knowledge has been obtained when the molecular weight is further reduced.

  Similarly, addition of a hydroxyl group-containing epoxidized polybutadiene can exhibit effects such as film-formability, improvement of curability by hydroxyl group, and improvement of developability. In addition, at least one or more of the phenoxy resin, butyral resin, and epoxidized polybutadiene having a hydroxyl group described above may be contained in a liquid adhesive or a sheet-like adhesive, Needless to say, curability and developability can be improved.

  Finally, a method for producing a sheet-like (film-like) adhesive will be described. In producing such a sheet-like adhesive, a general method can be used. For example, a varnish obtained by blending a cationically polymerizable resin and a photocationic polymerization initiator is coated on a base film, dried, and then the cover film is brought into close contact with each other to complete. Various surfactants can be blended in order to improve the coatability in this processing process. Examples thereof include a leveling agent for improving wettability to the base film and an antifoaming agent for preventing the generation of bubbles. Depending on the type of solvent, care must be taken because the solvent remaining in the adhesive even after drying may impair the curability. Moreover, since the uneven | corrugated state of a surface may be transcribe | transferred on the film surface after hardening, it is preferable to use a base film and a cover film with few unevenness | corrugations.

  Hereinafter, the present invention will be specifically described by way of examples.

  First, raw materials used for manufacturing the adhesive will be described.

  As the bisphenol type epoxy resin, “Epicoat 1006” which is solid at room temperature (epoxy equivalent 1100, manufactured by Japan Epoxy Resin Co., Ltd.), “YDF175S” which is liquid at room temperature (Bisphenol F type manufactured by Toto Kasei Co., Ltd.), liquid at room temperature “840S” (Dainippon Ink Industries, Ltd., bisphenol A type) was used.

  As an alicyclic epoxy resin, “Celoxide 2021P” (abbreviated as “CEL2021P”), which is liquid at room temperature, “YL7170” (manufactured by Japan Epoxy Resin Co., Ltd., hydrogenated bisphenol A type, solid at room temperature) Epoxy), “EHPE3150” (manufactured by Daicel Chemical Industries, Ltd., an epoxy resin that is a 1,2-epoxy-4- (2-oxiranyl) cyclosoxane adduct of 2,2-bis (hydroxymethyl) -1-butanol) It was used.

  As the oxetane compound, “OXT-121” (manufactured by Toagosei Co., Ltd., 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene) was used.

  As the phenoxy resin, “YP50” (manufactured by Toto Kasei Co., Ltd.) was used.

  As the epoxidized polybutadiene having a hydroxyl group, “PB3600” (manufactured by Daicel Chemical Industries, Ltd.) was used.

  “Denka Butyral 3000-1” (manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as the butyral resin.

  “SP-170” (manufactured by Asahi Denka Kogyo Co., Ltd.) was used as the photo cationic polymerization initiator, and “SI-150L” (manufactured by Sanshin Chemical Industry Co., Ltd.) was used as the thermal cationic polymerization initiator. Although this “SI-150L” is thermosetting, the sensitivity is inferior, but the curing reaction can be slightly initiated by light irradiation, but is generally commercially available for thermosetting. Further, “Photoinitiator 2074” (abbreviated as “PI2074”, manufactured by Rhodia Japan Co., Ltd.) was used as an initiator capable of similarly starting cationic curing with light or heat.

  As a solvent, anone (cyclohexanone), toluene, 2-butanone, and propylene glycol (industrial reagent) as a chain transfer additive were used.

(Formulation Examples 1-8)
The liquid adhesive was manufactured with the blending amounts (parts by weight) shown in Formulation Examples 1, 2, 7, and 8 in [Table 1] below. Specifically, the raw materials other than the cationic polymerization initiator and “PB3600” are weighed, heated to 100 ° C. with stirring and mixed, then cooled to room temperature, added with the cationic polymerization initiator, and stirred and mixed. “PB3600” was added to the mixture, heated to 80 ° C., stirred and mixed, allowed to cool to room temperature, filtered through a membrane filter having a pore size of 3 μm, and degassed under reduced pressure to obtain a liquid adhesive.

  The sheet-like adhesive was produced with the blending amounts (parts by weight) shown in Formulation Examples 3 to 6 in [Table 1] below. Specifically, the resin and solvent other than the cationic polymerization initiator are weighed, heated to 80 ° C. and mixed with stirring, then cooled to room temperature, added with the cationic polymerization initiator, mixed with stirring, and the pore size of 3 μm. The varnish was prepared by filtering through a membrane filter and degassing under reduced pressure. Subsequently, a sheet-like adhesive was produced using this varnish as follows. A varnish is applied to a 25 μm thick PET film (base film) with a bar coater, followed by primary drying at 80 ° C. for 10 minutes, followed by secondary drying at 120 ° C. for 10 minutes to obtain a sheet-like adhesive. It was. This sheet-like adhesive had no tackiness and the thickness of the coating film was 80 μm.

  Next, examples and comparative examples of bonding methods using the liquid and sheet-like adhesives obtained as described above will be described.

Example 1
Using the liquid adhesive shown in Formulation Example 1, printing was performed on an aluminum plate to a thickness of 20 μm (see FIG. 1B). This was subjected to UV exposure through a mask using a normal high-pressure mercury lamp type parallel exposure machine (see FIG. 1C). The mask used was a 50 μm wide line pattern arranged around a 5 mm square. The exposure was completed at a stage where energy (exposure amount) of ² J / cm ² was applied. The workpiece temperature at that time was 40 ° C. At this stage, no tack was observed on the surface of the irradiated product. Further, the irradiated product was subjected to a heat aging treatment at 100 ° C. for 10 minutes, followed by development treatment with a mixed solvent of isopropyl alcohol and acetone in a volume ratio of 7: 3 in an ultrasonic bath, and then solvent drying at 80 ° C. for 5 minutes ( (Refer FIG.1 (d)).

  Then, when the state of the formed heat-sensitive adhesive layer was observed with a microscope, pattern formation as in the mask was observed, no pattern chipping or development residue was observed, there was no peeling of the heat-sensitive adhesive layer, and good resistance It had developability / pattern formability. That is, it was confirmed that the pattern formability was excellent.

  In addition, a 100 μm thick, 7 mm square glass plate was overlaid on the B-staging pattern obtained as described above, and a 10 g weight was placed thereon, followed by heat treatment in an oven at 180 ° C. for 20 minutes ( (Refer FIG.1 (f)). After cooling at room temperature, the glass plate was firmly bonded. That is, it was confirmed that the glass plate adhesion was excellent.

Separately, using a mask having a 2 mm square opening, a 2 mm square B-staging pattern is formed by the same process, and a 2 mm square silicon chip is formed thereon using a flip chip bonder at 180 ° C., 30 ° C. Pressurized for 2 seconds. After the sample was further cured at 180 ° C. in an oven, the shear adhesive strength was measured by a bond tester and found to be 2.94 MPa (30 kgf / cm ² ).

  The above results are shown in [Table 2] below.

(Example 2)
In Example 1, in place of the liquid adhesive shown in Formulation Example 1, except that the liquid adhesive shown in Formulation Example 2 was used, the pattern formability and the glass plate were the same as in Example 1. Adhesion was evaluated and shear bond strength was measured. These results are shown in [Table 2] below.

(Example 3)
In Example 1, the pattern formation and glass plate adhesion were evaluated in exactly the same manner as in Example 1 except that the exposure dose was extended to 5 J / cm ² and no post-exposure after exposure was performed. The shear bond strength was measured. These results are shown in [Table 2] below.

Example 4
In Example 1, except that a spot-type high-pressure mercury lamp was used as an exposure machine, pattern forming property and glass plate adhesiveness were evaluated in the same manner as in Example 1, and shear adhesive strength was measured. These results are shown in [Table 2] below. However, in Example 4, the workpiece temperature at the start of exposure was room temperature (25 ° C.), but the workpiece temperature at the end of exposure was increased to 75 ° C.

(Example 5)
In Example 1, in place of the liquid adhesive shown in Formulation Example 1, except that the liquid adhesive shown in Formulation Example 7 was used, the pattern formability and the glass plate were the same as in Example 1. Adhesion was evaluated and shear bond strength was measured. These results are shown in [Table 2] below.

(Example 6)
In Example 1, in place of the liquid adhesive shown in Formulation Example 1, except that the liquid adhesive shown in Formulation Example 8 was used, the pattern formability and glass plate adhesion were the same as in Example 1. And the shear bond strength was measured. These results are shown in [Table 2] below.

(Comparative Example 1)
In Example 1, in place of the liquid adhesive shown in Formulation Example 1, except that a commercially available UV curable adhesive was used, pattern forming properties and glass plate adhesiveness were exactly the same as in Example 1. Evaluation and shear bond strength were measured. These results are shown in [Table 2] below.

  (* 1) The pattern formability was evaluated based on the following criteria.

  “A”: Pattern formation as observed in the mask is observed, and pattern chipping and development residue are not observed.

  “◯”: A pattern is formed, but a development residue appears in portions to be removed.

  “△”: Some of the pattern lines are missing.

  “X”: A pattern does not appear even after development, and the film remains.

  “XX”: All that was eluted during development.

  (* 2) Glass plate adhesion was evaluated based on the following criteria.

  “◎”: A material that is firmly bonded, does not peel off, and breaks the glass if it is forcibly removed.

  "○": Can be peeled off, but requires considerable force.

  “×”: A material that can be easily peeled off when a little force is applied.

  “XX”: Not thermally bonded.

(Example 7)
The sheet-like adhesive shown in Formulation Example 3 (resin thickness: 80 μm) is vacuum-laminated on the surface of the FR4 copper foil etched off (see FIG. 1B), and the inner dimension is 2 mm in line width through the base film. Is a close contact with a negative photomask having a rectangular pattern of 2 mm square, cured with an energy of 1500 mJ / cm ² with a light source of an ultra-high pressure mercury lamp (see FIG. 1C), peeled off the base film, 100 ° C., Heat treatment (heat aging) was performed for 10 minutes. Next, after developing with a mixed solvent having a volume ratio of isopropyl alcohol and acetone of 7: 3 in an ultrasonic bath, the solvent was dried at 80 ° C. for 5 minutes to form a heat-sensitive adhesive layer ( (Refer FIG.1 (d)). In addition, the workpiece | work temperature at the time of exposure was 40 degreeC.

  When the state of the formed heat-sensitive adhesive layer was observed with a microscope, this layer was not peeled off and had good development resistance. That is, it was confirmed that the pattern formability was excellent.

  Moreover, it replaced with the liquid adhesive shown to the compounding example 1, and evaluated the glass plate adhesiveness exactly like Example 1 except having used the sheet-like adhesive shown to the compounding example 3. The shear bond strength was measured. These results are shown in [Table 3] below.

(Example 8)
In Example 7, in place of the sheet-like adhesive shown in Formulation Example 3, except that the sheet-like adhesive shown in Formulation Example 4 was used, the pattern forming property and Glass plate adhesion was evaluated and shear bond strength was measured. These results are shown in [Table 3] below.

Example 9
In Example 7, in place of the sheet-like adhesive shown in Formulation Example 3, except that the sheet-like adhesive shown in Formulation Example 5 was used, the pattern forming property and Glass plate adhesion was evaluated and shear bond strength was measured. These results are shown in [Table 3] below.

(Example 10)
In Example 7, in place of the sheet-like adhesive shown in Formulation Example 3, except that the sheet-like adhesive shown in Formulation Example 6 was used, the pattern forming property and Glass plate adhesion was evaluated and shear bond strength was measured. These results are shown in [Table 3] below.

An example of embodiment of this invention is shown and (a)-(f) is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Adhering body 2 Adhering body 3 Adhesive layer 4 Negative type photomask 5 Heat-sensitive adhesive layer

Claims (8)

  A method of adhering two adherends at a part of an opposing adhesive surface, the step of forming an adhesive layer using an adhesive on the adhesive surface of one adherend, and through a negative photomask By irradiating the adhesive layer with light and exposing it, the step of changing the light-irradiated part into a B-stage heat-sensitive adhesive layer, and developing the part that was not irradiated with light at the time of exposure A bonding method comprising: a step of removing, and a step of bringing the heat-sensitive adhesive layer remaining after development into contact with the bonding surface of the other adherend and heating.   2. The bonding method according to claim 1, wherein the degree of B-staging of the heat-sensitive adhesive layer is adjusted by subjecting the adhesive layer to heat aging after exposure and before development.   The bonding method according to claim 1 or 2, wherein the temperature during exposure is 50 ° C or lower.   An adhesive used in the use of the adhesion method according to any one of claims 1 to 3, wherein the adhesive is a liquid or a sheet containing a cationically polymerizable resin and a photocationic polymerization initiator. adhesive.   The adhesive according to claim 4, wherein the cationically polymerizable resin is a compound having a cyclic structure containing an oxygen atom, and is cured by ring-opening polymerization.   6. The adhesive according to claim 5, wherein the compound having a cyclic structure containing an oxygen atom is an epoxy resin.   The adhesive according to any one of claims 4 to 6, comprising a thermal cationic polymerization initiator that generates cations by heating.   The adhesive according to any one of claims 4 to 7, comprising at least one of a phenoxy resin, a butyral resin, and an epoxidized polybutadiene having a hydroxyl group.

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