JP7006029B2 - Adhesive compositions and structures for circuit connections - Google Patents

Description

The present invention relates to an adhesive composition for circuit connection and a structure using the same.

In recent years, in the fields of semiconductors, liquid crystal displays and the like, various adhesives have been used for fixing electronic components or connecting circuits. In these applications, the density and the definition are getting higher and higher, and high adhesiveness or reliability is required for the adhesive. In particular, circuit connection materials include connection between a liquid crystal display and a tape carrier package (TCP), connection between a flexible printed circuit board (FPC) and TCP, and connection between an FPC and a printed wiring board (Printed Wiring Board). : PWB) connection, semiconductor silicon chip and board connection, FPC and touch panel module connection, FPC and FPC connection, COF (Chip On Flex) mounting method for COF FPC and PWB connection, COF An idiosyncratic conductive adhesive containing conductive particles is used in the connection between the FPC and the FPC (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 60-191228 Japanese Unexamined Patent Publication No. 1-2517787

In recent years, organic EL elements (OLEDs), liquid crystal display terminals (smartphones, tablets, smart watches, etc.), and wearable terminals (terminals to be worn) have been increasing. In recent years, for these terminals, a connection structure having FPC / FPC connection, FPC / FPC connection for COF, FPC / PWB connection, or FPC / PWB connection for COF via a circuit connection adhesive composition has been used. It has increased. For these connection structures, it is required to reduce the connection resistance in order to improve the display quality and reduce the power consumption. Further, since the above-mentioned terminals are often placed in a high temperature and high humidity environment, the connection structure is required to have high connection reliability that can maintain a low connection resistance even in a high temperature and high humidity environment. ..

Therefore, an object of the present invention is to provide an adhesive composition for circuit connection capable of obtaining a structure exhibiting low connection resistance and high connection reliability, and a structure using the same.

In order to achieve the above object, the present invention comprises (A) solder particles having a Bi content of 20 to 60% by mass and a Sn content of 40 to 80% by mass, and (B) a phosphoric acid ester-based organic substance. Provided is an adhesive composition for circuit connection, which comprises a compound, (C) a radically polymerizable compound, and (D) a radical generator.

According to the circuit connection adhesive composition, a structure capable of exhibiting low connection resistance, exhibiting excellent display quality, and reducing power consumption by containing the above-mentioned specific component. Can be obtained. In addition, the structure using the above-mentioned circuit connection adhesive composition stably shows low connection resistance even after the high temperature and high humidity environment test, so that it has high reliability that can maintain excellent display quality even in a harsh environment. Have. According to the above-mentioned adhesive composition for circuit connection, it is possible to provide a structure exhibiting these performances.

In FPC / FPC connection and FPC / PWB connection, there are many connection methods in which electrodes having a gold plating layer formed on the outermost surface are connected to each other, and a normal circuit connection adhesive composition can be used. Examples of the conductive particles used in the circuit connection adhesive composition include Au-plated plastic particles, Ni-plated plastic particles, metallic Ni particles, and the like, and the type of resin used in the circuit connection adhesive composition is Examples include an epoxy anion type and a radical acrylate type. However, in recent years, high display quality and low power consumption have been achieved because the electrical connection is made by the limited physical contact between the surface of the conductive particles and the surface of the electrode when these adhesive compositions for circuit connection are used. It is becoming difficult to meet market demands such as high connection reliability.

Further, in the FPC / PWB connection for COF and the FPC / FPC connection for COF, the electrode surface of the FPC for COF is Sn-plated, and the electrode surfaces of PWB and FPC are gold-plated. Since the electrical connection in the metal particles is made by the limited physical contact between the surface of the conductive particles and the surface of the electrodes, it is difficult to reduce the resistance.

Further, the present inventors have studied to reduce the connection resistance by forming a close interface or a partial metal bond between the electrode surface and the conductive particle surface in the circuit connection adhesive composition. rice field. We examined any solder particles and flux for any solder connection, but the resistance remained limited and the resistance could not be reduced. The resistance after the reliability test at 85 ° C and 85% RH was Rose. The term "metal bonding" as used herein means that a layer (metal interlayer compound) in which a metal element of solder as conductive particles and a metal element on the outermost surface of electrode plating are mixed is formed in a pressure-bonded body.

The present inventors have studied solder particles suitable for the ultimate crimping temperature of 130 to 180 ° C. The melting point of the BiSn solder particles was 139 ° C., which was considered to be optimal in the market demand. In these studies, it was found that the resistance could be reduced, but the resistance increased in the environmental test such as 85 ° C. and 85% RH.

As a result of diligent studies, the present inventors have (A) a Bi content of 20 to 60% by mass and a Sn content of 40 to 80% by mass in the radical curing adhesive composition for circuit connection. A circuit connection adhesive composition containing (B) a phosphate ester-based organic compound, (C) a radically polymerizable compound, and (D) a radical generator, thereby forming a pressure-bonded structure. We have found that it is possible to reduce the connection resistance and suppress the increase in resistance even in a harsh environment, and have completed the present invention.

In the circuit connection adhesive composition of the present invention, the Bi content of the solder particles (A) may be 21 to 40% by mass and the Sn content may be 79 to 60% by mass.

In the circuit connection adhesive composition of the present invention, the (B) phosphate ester-based organic compound may contain a monofunctional or polyfunctional phosphate ester-based (meth) acrylate monomer.

The circuit connection adhesive composition of the present invention may further contain (E) organic fine particles.

The adhesive composition of the present invention may further contain a silane coupling agent.

The present invention also provides a structure comprising the circuit connection adhesive composition of the present invention or a cured product thereof.

The present invention is further arranged between the first circuit member having the first circuit electrode, the second circuit member having the second circuit electrode, and the first circuit member and the second circuit member. The first circuit electrode and the second circuit electrode are electrically connected to each other, and the circuit connection member is the circuit connection adhesive composition of the present invention or a circuit connection adhesive composition thereof. Provided is a structure containing a cured product.

In the structure of the present invention, the first circuit electrode is an electrode having an Au plating layer on the outermost surface, and the second circuit electrode is an electrode having an Au plating layer or a Sn plating layer on the outermost surface. You may.

According to the present invention, there is provided an adhesive composition for circuit connection capable of obtaining a structure exhibiting low connection resistance and high connection reliability, and a structure using the same (circuit connection structure or the like). be able to.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an application of an adhesive composition for circuit connection or a cured product thereof to a structure (circuit connection structure or the like) or a structure thereof. INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an adhesive composition for circuit connection or a cured product thereof for circuit connection. INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an application of a structure to a wearable application.

It is a schematic cross-sectional view which shows one Embodiment of the structure of this invention. It is a schematic sectional drawing which shows the other embodiment of the structure of this invention. It is a schematic sectional drawing which shows the other embodiment of the structure of this invention. It is a schematic sectional drawing which shows the other embodiment of the structure of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

As used herein, the term "(meth) acrylate" means at least one of an acrylate and a corresponding methacrylate. The same applies to other similar expressions such as "(meth) acryloyl" and "(meth) acrylic acid". Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. The content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. The numerical range indicated by using "-" indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively. "A or B" may include either A or B, and may include both. "Room temperature" means 25 ° C.

In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value of the numerical range of one step may be replaced with the upper limit value or the lower limit value of the numerical range of another step. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

<Adhesive composition>
The adhesive composition of the present embodiment has (A) solder particles having a Bi content of 20 to 60% by mass and a Sn content of 40 to 80% by mass (hereinafter, also referred to as “component (A)”). , (B) Phosphoric acid ester organic compound (hereinafter, also referred to as "(B) component"), (C) radically polymerizable compound (hereinafter, also referred to as "(C) component"), and (D) radical. A circuit connection adhesive composition containing a generator (hereinafter, also referred to as “component (D)”). Further, the adhesive composition may further contain (E) organic fine particles (hereinafter, also referred to as “(E) component”). Hereinafter, each component will be described.

((A) component: solder particles)
The adhesive composition of the present embodiment contains solder particles as conductive particles. Depending on the type, the solder particles exist in a mixed state of a solid state and a liquid state at a certain temperature. For example, Sn88-In8.0-Ag3.5-Bi0.5 solder is solid at around 160 ° C, but endothermic at around 196 ° C, and solid and liquid states coexist at around 200 ° C. Further, it absorbs heat at around 206 ° C and becomes completely liquid. A DSC (Differential Scan Calorimetry) was used to investigate the characteristics of these solders. For example, the endothermic peak of the solder occurs at the first point around 196 ° C and at the second point around 206 ° C. In the present specification, this is referred to as a first exothermic peak and a second exothermic peak, respectively. The first exothermic peak and the second exothermic peak are values measured in the He gas flow at a heating rate of 10 ° C./min in the present embodiment.

From the viewpoint of the crimping temperature, the solder particles in the present embodiment are preferably solder particles having a first endothermic peak of 130 to 170 ° C. in DSC, and more preferably BiSn solder particles having a first endothermic peak of 139 ° C. in DSC.

In the present embodiment, solder particles having a Bi (bismuth) content of 20 to 60% by mass and a Sn (tin) content of 40 to 80% by mass are used as the component (A). (A) The solder particles are preferably solder particles having a Bi content of 21 to 58% by mass and a Sn content of 79 to 42% by mass, and have a Bi content of 21 to 40% by mass. Solder particles having a Sn content of 79 to 60% by mass are more preferable. When the composition of Bi and Sn is within the above range, the solder component in the liquid state melted at around 139 ° C. and the solder component in the solid state are mixed at the time of heat crimping, and the electrodes are connected while maintaining the distance between the electrodes. It is possible for solder particles to wet and spread on the surface to form close and widespread physical contact and partial metal joints. This makes it possible to achieve low connection resistance and high connection reliability.

(A) The solder particles may contain only Bi and Sn as metal elements, and may further contain other metal elements as long as the Bi content and Sn content are within the above-mentioned ranges. Examples of other metal elements include general metal elements that can be contained in solder. From the viewpoint of low connection resistance and high connection reliability, (A) the only metal elements contained in the solder particles are Bi and Sn (that is, the total of Bi content and Sn content is 100% by mass). preferable.

(A) The average particle size of the solder particles may be arbitrarily selected according to the size of the electrode and the space portion of the crimping structure. The average particle size is preferably 1/3 to 1/50 times the size of the space portion in order to avoid a short circuit due to coupling between adjacent circuit electrodes. Generally, the average particle size of (A) solder particles may be 0.1 to 30 μm or 0.5 to 10 μm. (A) The average particle size of the solder particles can be measured by using instrumental analysis such as a laser diffraction method, for example.

(A) The amount of solder particles added is preferably adjusted appropriately in consideration of the required resistance and avoiding short circuit due to particle connection between adjacent circuit electrodes. In general, when the sum of the resin component to be added and the radically polymerizable compound is 100 parts by mass, 1 to 30 parts by mass is often added to the sum, and 2 to 20 parts by mass may be added. ..

(Component (B): Phosphate ester-based organic compound)
(B) The phosphate ester-based organic compound enhances the activity of the surface of the solder particles and the surface of the circuit electrode, and develops a partial metal bond between the solder particle interface and the electrode interface and a close and wide contact interface with the solder particles. Has an effect. The phosphoric acid ester-based organic compound is preferably a monofunctional or polyfunctional phosphoric acid ester-based radically polymerizable compound. In particular, as the phosphoric acid ester-based radically polymerizable compound, it is preferable to use a radically polymerizable compound having a phosphoric acid ester structure represented by the following general formula (I) or (II), and radicals such as (meth) acrylate compounds are used. It is more preferable to use the polymerizable compound in combination with the radically polymerizable compound having a phosphate ester structure represented by the formula (I) or (II). In the present invention, the phosphoric acid ester-based radically polymerizable compound is classified into (B) a phosphoric acid ester-based organic compound, not (C) a radically polymerizable compound described later.

［式中、ｎは１～３の整数を示し、Ｒは、水素原子又はメチル基を示す。］

［式中、ａは１～３の整数を示す。］

[In the formula, n represents an integer of 1 to 3, and R represents a hydrogen atom or a methyl group. ]

[In the formula, a indicates an integer of 1 to 3. ]

The radically polymerizable compound having the phosphoric acid ester structure can be obtained, for example, by reacting anhydrous phosphoric acid with 2-hydroxyethyl (meth) acrylate. Specific examples of the radically polymerizable compound having the phosphoric acid ester structure include mono (2- (meth) acryloyloxyethyl) acid phosphate, di (2- (meth) acryloyloxyethyl) acid phosphate and the like. .. The radically polymerizable compound having a phosphoric acid ester structure represented by the formula (I) or (II) may be used alone or in combination of two or more.

The content of the radically polymerizable compound having a phosphoric acid ester structure represented by the formula (I) or (II) is (C) from the viewpoint of facilitating the formation of a partial metal bond between the solder particle interface and the electrode interface. ) The total amount of the component and the film forming material (component used if necessary) is 90 parts by mass, preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass. When this content is 0.5 parts by mass or more, the effect of partial metal bonding is likely to be exhibited, and when it is 15 parts by mass or less, deterioration of workability in the transfer step and the heating and pressurizing step due to stickiness is suppressed. be able to.

The content of the (B) phosphate ester-based organic compound is the content of the component (C) and the film forming material (component used as necessary) from the viewpoint of the effect of partial metal bonding and workability in the transfer step and the crimping step. It is preferably 0.5 to 15 parts by mass, and more preferably 1 to 10 parts by mass with respect to 90 parts by mass of the total amount.

(Component (C): radically polymerizable compound)
The radically polymerizable compound is a compound having a functional group capable of radical polymerization. Examples of such radically polymerizable compounds include (meth) acrylate compounds, maleimide compounds, citraconimide compounds, and nadiimide compounds. The "(meth) acrylate compound" means a compound having a (meth) acryloyl group. The radically polymerizable compound may be used in the state of a monomer or an oligomer, and the monomer and the oligomer may be used in combination. The radically polymerizable compound may be used alone or in combination of two or more.

Specific examples of the (meth) acrylate compound include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, ethylene glycol di (meth) acrylate, and diethylene glycol di (meth) acrylate. Trimethylol Propane Tri (meth) Acrylate, Tetramethylol Methantetra (Meta) Acrylate, 2-Hydroxy-1,3-di (Meta) Acryloxy Propane, 2,2-Bis [4-((Meta) Acryloxymethoxy) Phenyl] propane, 2,2-bis [4-((meth) acryloxypolyethoxy) phenyl] propane, dicyclopentenyl (meth) acrylate, tricyclodecanyl (meth) acrylate, tris ((meth) acryloyloxyethyl) ) Isocyanurate, isocyanuric acid EO-modified di (meth) acrylate, isocyanuric acid EO-modified tri (meth) acrylate, urethane (meth) acrylate and the like. As the radically polymerizable compound other than the (meth) acrylate compound, for example, the compound described in International Publication No. 2009/0638227 can be preferably used. The (meth) acrylate compound may be used alone or in combination of two or more.

As the radically polymerizable compound (C), a (meth) acrylate compound is preferable, and a urethane (meth) acrylate is more preferable, from the viewpoint of obtaining further excellent connection reliability. From the viewpoint of improving heat resistance, the (meth) acrylate compound preferably has at least one substituent selected from the group consisting of a dicyclopentenyl group, a tricyclodecanyl group and a triazine ring.

(C) The radically polymerizable compound may contain an allyl (meth) acrylate. In this case, the content of the allyl (meth) acrylate is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass in total of the (C) radically polymerizable compound and the film forming material (components used as necessary). , 0.5 to 5 parts by mass is more preferable.

The content of the radically polymerizable compound (C) is preferably at least the following lower limit from the viewpoint of maintaining the initial adhesive strength and the adhesive strength after the reliability test, and the workability in the transfer step and the workability in the connection step. From the viewpoint of the above, it is preferable that the value is not more than the following upper limit. The content of the radically polymerizable compound (C) is preferably in the following range based on the total mass of the adhesive component (solid content other than conductive particles in the adhesive composition; the same applies hereinafter) of the adhesive composition. The content of the radically polymerizable compound (C) is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more. The content of the radically polymerizable compound (C) is preferably 90% by mass or less, more preferably 80% by mass or less, and further preferably 70% by mass or less. From these viewpoints, the content of the (C) radically polymerizable compound is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and further preferably 30 to 70% by mass. preferable.

(Component (D): radical generator)
The radical generator is a curing agent (radical polymerization initiator, etc.) that is decomposed by heat, ultrasonic waves, electromagnetic waves, or the like to generate free radicals.

Examples of the radical generator include peroxides (organic peroxides and the like), azo compounds and the like. The radical generator is appropriately selected according to the target connection temperature, connection time, pot life, and the like. The 10-hour half-life temperature of the radical generator is preferably 40 ° C. or higher, more preferably 60 ° C. or higher, from the viewpoint of high reactivity and improvement of pot life. The 1-minute half-life temperature of the radical generator is preferably 180 ° C. or lower, more preferably 170 ° C. or lower, from the viewpoint of high reactivity and improvement of pot life. From the viewpoint of high reactivity and improvement of pot life, the radical generator is preferably an organic peroxide having a 10-hour half-life temperature of 40 ° C. or higher and a 1-minute half-life temperature of 180 ° C. or lower, and has a 10-hour half-life. Organic peroxides having a temperature of 60 ° C. or higher and a one-minute half-life temperature of 170 ° C. or lower are more preferable.

Specific examples of peroxides, which are curing agents that generate free radicals by heat, include diacyl peroxides (benzoyl peroxides, etc.), peroxydicarbonates, peroxyesters, peroxyketals, dialkyl peroxides, and hydroperoxides. , Cyril peroxide and the like.

As the radical generator, a curing agent having a concentration of chlorine ions and organic acids of 5000 ppm or less is preferable from the viewpoint of suppressing corrosion of electrodes (circuit electrodes, etc.), and a curing agent having a small amount of organic acids generated after thermal decomposition is preferable. Is more preferable. Specific examples of such a curing agent include diacyl peroxide, peroxydicarbonate, peroxyester, dialkyl peroxide, hydroperoxide, silyl peroxide and the like, and diacyl from the viewpoint of obtaining high reactivity. At least one selected from the group consisting of peroxides, peroxydicarbonates and peroxyesters is preferable. The curing agent that generates free radicals by heat may be used alone or in combination of two or more.

Peroxyesters include cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, and t-hexyl. Peroxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-di (2-) Ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate Ate, t-butylperoxyisobutyrate, 1,1-bis (t-butylperoxy) cyclohexane, t-hexylperoxyisopropylmonocarbonate, t-butylperoxy-3,5,5-trimethylhexanoate , T-Butylperoxylaurate, 2,5-dimethyl-2,5-di (m-toloilperoxy) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate , T-hexyl peroxybenzoate, t-butyl peroxyacetate and the like. The peroxy ester may be used alone or in combination of two or more. As the curing agent that generates free radicals by heat other than the peroxyester, for example, the compound described in International Publication No. 2009/063827 can be preferably used.

Examples of the azo compound that is a curing agent that generates free radicals by heat include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis. (Cyclohexane-1-carbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2' -Azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'-azobis [2 -(Imidazoline-2-yl) propane] and the like.

The radical generator may be used alone or in combination of two or more. A curing agent (peroxide, azo compound, etc.) that generates free radicals by heat may be used in combination with a decomposition accelerator, a decomposition inhibitor, or the like. Further, the radical generator may be coated with a polyurethane-based or polyester-based polymer substance or the like and microencapsulated. Microencapsulated hardeners are preferred because of their extended pot life.

The content of the radical generator is preferably in the following range from the viewpoint that a sufficient reaction rate can be easily obtained when the connection time is 25 seconds or less. The content of the radical generator is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and 1 part by mass or more with respect to 100 parts by mass of the radically polymerizable compound. Is even more preferable. The content of the radical generator is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound. .. From these viewpoints, the content of the radical generator is preferably 0.1 to 40 parts by mass and 0.5 to 30 parts by mass with respect to 100 parts by mass of the radically polymerizable compound. It is more preferably 1 to 30 parts by mass, further preferably 1 to 30 parts by mass.

The content of the radical generator is preferably in the following range from the viewpoint that a sufficient reaction rate can be easily obtained when the connection time is 25 seconds or less. The content of the radical generator is preferably 0.1 part by mass or more, preferably 0.5 part by mass, based on 100 parts by mass of the total of the radically polymerizable compound and the film forming material (components used as necessary). The above is more preferable, and it is further preferable that the amount is 1 part by mass or more. The content of the radical generator is preferably 40 parts by mass or less, preferably 30 parts by mass or less, based on 100 parts by mass of the total of the radically polymerizable compound and the film forming material (components used as necessary). Is more preferable, and 20 parts by mass or less is further preferable. From these viewpoints, the content of the radical generator is preferably 0.1 to 40 parts by mass with respect to 100 parts by mass in total of the radically polymerizable compound and the film forming material (components used as necessary). , 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass.

The content of the radical generator when the connection time is not limited is preferably in the following range from the viewpoint that a sufficient reaction rate can be easily obtained. The content of the radical generator is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and 1 part by mass or more with respect to 100 parts by mass of the radically polymerizable compound. Is even more preferable. The content of the radical generator is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 15 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound. .. From these viewpoints, the content of the radical generator is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the radically polymerizable compound. It is more preferably 1 to 15 parts by mass.

The content of the radical generator when the connection time is not limited is preferably in the following range from the viewpoint that a sufficient reaction rate can be easily obtained. The content of the radical generator is preferably 0.1 part by mass or more, preferably 0.5 part by mass, based on 100 parts by mass of the total of the radically polymerizable compound and the film forming material (components used as necessary). The above is more preferable, and it is further preferable that the amount is 1 part by mass or more. The content of the radical generator is preferably 30 parts by mass or less, preferably 20 parts by mass or less, based on 100 parts by mass of the total of the radically polymerizable compound and the film forming material (components used as necessary). Is more preferable, and it is further preferable that the amount is 15 parts by mass or less. From these viewpoints, the content of the radical generator is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the total of the radically polymerizable compound and the film forming material (components used as necessary). , 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass.

((E) component: organic fine particles)
From the viewpoint of high connection reliability, it is preferable that the adhesive composition of the present embodiment can maintain a constant connection distance between the electrodes of the structure after pressure bonding with higher accuracy. From this point of view, (E) organic fine particles (organic insulating fine particles) may be used as a gap control agent. These organic insulating fine particles are preferably (A) having an average particle size of 1/6 to 1.5 times the average particle size of the solder particles, and in a flat indenter test using a Fisher hardness tester at room temperature. At a maximum load of 5 mN and a load rate of 0.33 mN / sec, organic fine particles having a characteristic that the short diameter after deformation is 1/6 to 2/3 times the average particle size of the solder particles (A) are preferable. Examples of the organic fine particles having these characteristics include, but are not limited to, the contents of the present invention, polystyrene fine particles, methyl polyacrylate fine particles, polymethyl methacrylate fine particles, and the like. The average particle size of the organic fine particles can be measured by the same method as the average particle size of the solder particles.

The content of (E) organic particles is relative to the content of (A) solder particles from the viewpoint of high connection reliability and more accurately keeping the connection distance between the electrodes of the structure after crimping constant. The mass ratio is preferably 1/300 to 2/3 times, more preferably 1/200 to 1/2 times.

(Silane coupling agent)
The adhesive composition of the present embodiment may contain a silane coupling agent. By using a silane coupling agent, the adhesive force (adhesive force to glass, etc.) of the adhesive composition can be increased. Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3- (meth) acryloxypropylmethyldimethoxy. Silane, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropylmethyldiethoxysilane, 3- (meth) acryloxylpropyltriethoxysilane, N-2- (aminoethyl) -3- Aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isoxapropyltriethoxysilane, and condensates thereof. Be done.

The content of the silane coupling agent is preferably 0.1 to 10% by mass, more preferably 0.25 to 5% by mass, based on the total mass of the adhesive components of the adhesive composition. When the content of the silane coupling agent is 0.1% by mass or more, the effect of suppressing the generation of exfoliated bubbles at the interface between the circuit member and the circuit connecting material tends to be further increased, and the silane coupling agent is contained. When the amount is 10% by mass or less, the pot life of the adhesive composition tends to be long.

(Film forming material)
The adhesive composition of the present embodiment may contain a film-forming material, if necessary. The film-forming material improves the handleability of the film under normal conditions (normal temperature and pressure) when the liquid adhesive composition is solidified into a film, and has characteristics such as resistance to tearing, resistance to cracking, and resistance to stickiness. Can be applied to the film. Examples of the film forming material include phenoxy resin, polyvinyl formal, polystyrene, polyvinyl butyral, polyester, polyamide, xylene resin, polyurethane and the like. Among these, phenoxy resin is preferable from the viewpoint of excellent adhesiveness, compatibility, heat resistance and mechanical strength. The film forming material may be used alone or in combination of two or more.

Examples of the phenoxy resin include a resin obtained by double-adding a bifunctional epoxy resin and a bifunctional phenol, and a resin obtained by reacting the bifunctional phenol with epihalohydrin until polymerization. Can be mentioned. The phenoxy resin contains, for example, 1 mol of bifunctional phenol and 0.985 to 1.015 mol of epihalohydrin in the presence of a catalyst such as an alkali metal hydroxide at a temperature of 40 to 120 ° C. in a non-reactive solvent. It can be obtained by reacting. As the phenoxy resin, from the viewpoint of excellent mechanical and thermal properties of the resin, the compounding equivalent ratio of the bifunctional epoxy resin and the bifunctional phenols is particularly set to epoxy group / phenol hydroxyl group = 1 / 0.9 to. It is set to 1 / 1.1, and organic solvents (amide-based, ether-based, ketone-based, lactone-based, alcohol-based) having a boiling point of 120 ° C. or higher in the presence of catalysts such as alkali metal compounds, organic phosphorus compounds, and cyclic amine compounds. Etc.), a resin obtained by heating to 50 to 200 ° C. under the condition that the reaction solid content is 50% by mass or less and performing a heavy addition reaction is preferable. The phenoxy resin may be used alone or in combination of two or more.

Examples of the bifunctional epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy resin, biphenyl diglycidyl ether, and methyl-substituted biphenyl diglycidyl ether. Bifunctional phenols are compounds having two phenolic hydroxyl groups. Examples of the bifunctional phenols include bisphenols such as hydroquinones, bisphenol A, bisphenol F, bisphenol AD, bisphenol S, bisphenol fluorene, methyl-substituted bisphenol fluorene, dihydroxybiphenyl and methyl-substituted dihydroxybiphenyl. The phenoxy resin may be modified (for example, epoxy-modified) with a radically polymerizable functional group or other reactive compound.

The content of the film-forming material is preferably 10 to 90% by mass, more preferably 20 to 60% by mass, based on the total mass of the adhesive components of the adhesive composition.

(Other ingredients)
The adhesive composition of the present embodiment may contain conductive particles other than (A) solder particles, if necessary. Examples of the constituent materials of the other conductive particles include gold (Au), silver (Ag), nickel (Ni), copper (Cu), metals such as solder, and carbon. Further, coated conductive particles in which a non-conductive resin, glass, ceramic, plastic or the like is used as a core and the core is coated with the above metal (metal particles or the like) or carbon may be used. Since the coated conductive particles (for example, conductive particles having a plastic core) or the heat-molten metal particles are deformable by heating and pressurizing, the height variation of the circuit electrode is eliminated at the time of connection, and the contact area with the electrode at the time of connection is eliminated. Is preferable because the reliability is improved because the number of particles increases. Further, as the other conductive particles, solder particles having a composition other than the solder particles as the component (A) may be used.

The average particle size of the other conductive particles is preferably 1 to 30 μm from the viewpoint of excellent dispersibility and conductivity. The average particle size of the conductive particles can be measured using, for example, instrumental analysis such as laser diffraction. When other conductive particles are added, the content thereof is preferably 0.1 part by mass or more, preferably 1 part by mass or more, based on 100 parts by mass of the adhesive component of the adhesive composition from the viewpoint of excellent conductivity. More preferred. The content of the conductive particles is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, based on 100 parts by mass of the adhesive component of the adhesive composition, from the viewpoint of easily suppressing a short circuit of the electrodes (circuit electrodes, etc.). preferable. From these viewpoints, the content of the conductive particles is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass.

The adhesive composition of the present embodiment may appropriately contain a polymerization inhibitor such as hydroquinone and methyl ether hydroquinone, if necessary.

The adhesive composition of the present embodiment is a homopolymer or a copolymer obtained by polymerizing at least one monomer component selected from the group consisting of (meth) acrylic acid, (meth) acrylic acid ester and acrylonitrile. It may be further contained. From the viewpoint of excellent stress relaxation, the adhesive composition of the present embodiment preferably contains acrylic rubber or the like, which is a copolymer obtained by polymerizing a glycidyl (meth) acrylate having a glycidyl ether group. The weight average molecular weight of the acrylic rubber is preferably 200,000 or more from the viewpoint of enhancing the cohesive force of the adhesive composition.

The adhesive composition of the present embodiment may contain coated fine particles in which the surface of conductive particles ((A) solder particles or other conductive particles) is coated with a polymer resin or the like. When such coated fine particles are used in combination with conductive particles, even when the content of the conductive particles increases, it is easy to suppress a short circuit due to contact between the conductive particles, so that the insulation between adjacent circuit electrodes can be improved. Can be improved. The coated fine particles may be used alone without using the conductive particles, or the coated fine particles and the conductive particles may be used in combination.

The adhesive composition of the present embodiment includes rubber fine particles, a filler, a softener, an accelerator, an antiaging agent, a colorant, a flame retardant, a thixotropic agent, a coupling agent, a phenol resin, a melamine resin, and isocyanates. Etc. can also be contained. The adhesive composition of the present embodiment may appropriately contain additives such as an adhesion improver (excluding a coupling agent), a thickener, a leveling agent, a colorant, and a weather resistance improver.

The rubber fine particles have an average particle size of (A) less than twice the average particle size of the solder particles, and have a storage elastic modulus at room temperature (A) storage of the solder particles and the adhesive composition at room temperature. Particles having an elastic modulus of 1/2 or less are preferable. In particular, when the material of the rubber fine particles is silicone, acrylic emulsion, SBR, NBR or polybutadiene rubber, it is preferable to use the rubber fine particles alone or in combination of two or more. The three-dimensionally crosslinked rubber fine particles have excellent solvent resistance and are easily dispersed in the adhesive composition.

The filler can improve the electrical characteristics (connection reliability, etc.) between the circuit electrodes. As the filler, for example, particles having an average particle size of 1/4 or less of the average particle size of the solder particles (A) can be preferably used. When non-conductive particles are used in combination with a filler, particles having an average particle size or less of the non-conductive particles can be used as the filler. The content of the filler is preferably 5 to 60% by mass based on the total mass of the adhesive components of the adhesive composition. When the content is 60% by mass or less, the effect of improving the connection reliability tends to be further sufficiently obtained. When the content is 5% by mass or more, the effect of adding the filler tends to be sufficiently obtained.

The adhesive composition of the present embodiment can be used in the form of a paste when it is liquid at room temperature. When the adhesive composition is in a solid state at room temperature, it may be used by heating it, or it may be made into a paste by using a solvent. The solvent that can be used is not particularly limited as long as it is a solvent that is not reactive with the components in the adhesive composition and exhibits sufficient solubility. The solvent is preferably a solvent having a boiling point of 50 to 150 ° C. at normal pressure. When the boiling point is 50 ° C. or higher, the solvent is poorly volatile at room temperature, so that it can be used even in an open system. When the boiling point is 150 ° C. or lower, it is easy to volatilize the solvent, so that good reliability can be obtained after bonding.

The adhesive composition of the present embodiment may be in the form of a film. If necessary, a solution of the adhesive composition containing a solvent or the like is applied onto a fluororesin film, a polyethylene terephthalate film, or a releaseable base material (release paper, etc.), and then the solvent or the like is removed to form a film. An adhesive composition can be obtained. Further, a film-like adhesive composition can be obtained by impregnating a base material such as a non-woven fabric with the above solution, placing it on a peelable base material, and then removing the solvent or the like. When the adhesive composition is used in the form of a film, it is more convenient from the viewpoint of excellent handleability and the like.

When a film-like adhesive composition with a peelable base material is used for forming a connecting structure, the film-like adhesive composition side is placed on the first adherend side, and the peelable base material side on the opposite side is used. A step of transferring the film-shaped adhesive composition to the first adherend and peeling the peelable substrate from the film-shaped adhesive composition by heat-pressing is required (transfer step). The heating temperature is not particularly limited, but is preferably a temperature of 50 to 100 ° C. when a predetermined number of seconds is reached (the temperature reached when heat crimping is performed for a predetermined number of seconds). The pressure is not particularly limited as long as it does not damage the adherend, but is preferably 0.1 to 2 MPa. Heating and pressurization are preferably performed in the range of 0.3 seconds to 3 seconds. After installing the second adherend on the first adherend to which the film-like adhesive composition from which the peelable substrate has been peeled off by the transfer step is attached, the process proceeds to the heating and pressurizing step.

The adhesive composition of the present embodiment can be adhered, for example, by heating and pressurizing. By using both heating and light irradiation, adhesion can be performed at a lower temperature in a short time. The heating temperature is not particularly limited, but is preferably a temperature of 130 to 180 ° C. when a predetermined number of seconds is reached. The pressure is not particularly limited as long as it does not damage the adherend, but is preferably 0.1 to 10 MPa. Heating and pressurization are preferably performed in the range of 0.5 seconds to 30 seconds.

The adhesive composition of the present embodiment may be used as an adhesive for the same type of adherend, or may be used as an adhesive for different types of adherends having different coefficients of thermal expansion. Specifically, it is used as a circuit connection material typified by an anisotropic conductive adhesive, a silver paste, a silver film, etc .; an elastomer for CSP, an underfill material for CSP, a semiconductor element adhesive material typified by LOC tape, etc. be able to.

<Structure and its manufacturing method>
(First aspect)
The structure (circuit connection structure) of the present embodiment includes the adhesive composition of the present embodiment or a cured product thereof. The structure of the present embodiment is, for example, a connection structure for a display input circuit or as a connector substitute circuit. As one aspect of the structure of the present embodiment, the circuit connection structure includes a first circuit member having a first circuit electrode, a second circuit member having a second circuit electrode, and a first circuit member. And a circuit connecting member arranged between the second circuit members.

FIG. 1 is a schematic cross-sectional view showing the first aspect of the structure. In the structure 100 shown in FIG. 1, the first circuit member is a printed wiring board (FR-4 board or the like) including a board 11 such as a glass epoxy board and a circuit electrode 15 formed on the board 11. PWB) 10. The circuit electrode 15 is an electrode having an Au plating layer 14 on the outermost surface, in which a Ni (nickel) plating layer 13 and an Au (gold) plating layer 14 are sequentially formed on a copper circuit (copper foil circuit) 12. In some cases, an insulating layer (not shown) may be arranged on the main surface of the substrate 11 (the surface on which the circuit electrode 15 is provided). The second circuit member is a flexible circuit board (FPC) 20 including a substrate 21 such as a polyimide film substrate and a circuit electrode 25 formed on the substrate 21. The circuit electrode 25 is an electrode having an Au plating layer 24 on the outermost surface, in which a Ni plating layer 23 and an Au plating layer 24 are sequentially formed on a copper circuit (copper foil circuit) 22. In some cases, an insulating layer (not shown) may be arranged on the main surface (the surface on which the circuit electrode 25 is provided) of the substrate 21.

In the structure 100, the circuit electrode 15 (first circuit electrode) and the circuit electrode 25 (second circuit electrode) are opposed to each other and electrically connected to each other. A circuit connection member 50 for connecting the printed wiring board 10 and the flexible circuit board 20 is arranged. The circuit connection member 50 contains the adhesive composition of the present embodiment or a cured product thereof. That is, the circuit connection member contains an insulating substance (a component excluding conductive particles or a cured product thereof) 51 and conductive particles 52, and the conductive particles include (A) solder particles.

(Second aspect)
FIG. 2 is a schematic cross-sectional view showing a second aspect of the structure. In the structure 200 shown in FIG. 2, both the first and second circuit members are the flexible circuit boards 20 described in the first aspect. In the structure 200, the circuit electrode 25 (first circuit electrode) and the circuit electrode 25 (second circuit electrode) are opposed to each other and electrically connected to each other. A circuit connection member 50 for connecting the flexible circuit board 20 and the flexible circuit board 20 is arranged. The circuit connection member 50 contains the adhesive composition of the present embodiment or a cured product thereof.

(Third aspect)
FIG. 3 is a schematic cross-sectional view showing a third aspect of the structure. In the structure 300 shown in FIG. 3, the first circuit member is the printed wiring board 10 described in the first aspect. The second circuit member is a flexible circuit board (COF FPC) 30 used in a COF mounting method, which comprises a substrate 31 such as a polyimide film substrate and a circuit electrode 35 formed on the substrate 31. The circuit electrode 35 is an electrode having a Sn plating layer 33 formed on a copper circuit (copper foil circuit) 32 and having a Sn plating layer 33 on the outermost surface. In some cases, an insulating layer (not shown) may be arranged on the main surface of the substrate 31 (the surface on which the circuit electrode 35 is provided). In the structure 300, the circuit electrode 15 (first circuit electrode) and the circuit electrode 35 (second circuit electrode) are opposed to each other and electrically connected to each other. A circuit connection member 50 for connecting the printed wiring board 10 and the COF flexible circuit board 30 is arranged. The circuit connection member 50 contains the adhesive composition of the present embodiment or a cured product thereof.

(Fourth aspect)
FIG. 4 is a schematic cross-sectional view showing a fourth aspect of the structure. In the structure 400 shown in FIG. 4, the first circuit member is the flexible circuit board 20 described in the first aspect, and the second circuit member is used in the COF mounting method described in the third aspect. The flexible circuit board 30. In the structure 400, the circuit electrode 25 (first circuit electrode) and the circuit electrode 35 (second circuit electrode) are opposed to each other and electrically connected to each other. A circuit connection member 50 for connecting the flexible circuit board 20 and the COF flexible circuit board 30 is arranged. The circuit connection member 50 contains the adhesive composition of the present embodiment or a cured product thereof.

The structures of the first and second aspects described above are those in which electrodes having Au plating on the outermost surface are connected to each other, and the structures of the third and fourth aspects have Au plating on the outermost surface. The electrode is connected to the electrode with Sn plating on the outermost surface. In these connection methods, by connecting the electrodes via a circuit connection member containing the adhesive composition of the present embodiment or a cured product thereof, the connection resistance is lowered and the connection is made even in a high temperature and high humidity environment. It is possible to realize high reliability that can keep the resistance low.

The method for producing a structure of the present embodiment includes a step of curing the adhesive composition of the present embodiment. As one aspect of the method for manufacturing the structure of the present embodiment, the method for manufacturing the circuit connection structure includes a first circuit member having a first circuit electrode and a second circuit member having a second circuit electrode. In the arrangement step of arranging the adhesive composition of the present embodiment between the two, the first circuit member and the second circuit member are pressurized to electrically press the first circuit electrode and the second circuit electrode. It also comprises a heating and pressurizing step of heating and curing the adhesive composition. In the arrangement step, the first circuit electrode and the second circuit electrode can be arranged so as to face each other. In the heating and pressurizing step, the first circuit member and the second circuit member can be pressurized in opposite directions. In the method for manufacturing the structure of the present embodiment, the adhesive composition of the present embodiment is interposed between the circuit electrodes of the semiconductor elements facing each other and the circuit electrodes of the semiconductor mounting substrate, and the circuit electrodes facing each other are added. It may be a mode in which pressure is applied to electrically connect the electrodes in the pressurizing direction.

In the heating and pressurizing step, the heating temperature is not particularly limited, but is preferably a temperature of 130 to 180 ° C. when a predetermined number of seconds is reached. The pressure is not particularly limited as long as it does not damage the first circuit member and the second circuit member, but is preferably 0.1 to 10 MPa. Heating and pressurization are preferably performed in the range of 0.5 seconds to 30 seconds.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

<Manufacturing of film-shaped circuit connection material>
(Example 1)
A phenoxy resin having a solid content of 40% by mass by dissolving 50 g of a phenoxy resin (trade name: PKHC, manufactured by Union Carbide Co., Ltd., weight average molecular weight 45,000) in a mixed solvent of toluene / ethyl acetate (mass ratio: 50/50). A solution was prepared. As radically polymerizable compounds, isocyanuric acid EO-modified diacrylate (trade name: M-215, manufactured by Toa Synthetic Co., Ltd.), 2-methacryloyloxyethyl acid phosphate (phosphate ester, trade name: light ester P-2M, Kyoeisha Co., Ltd.) Chemical Co., Ltd.) and urethane acrylate (trade name: U-2PPA, manufactured by Shin-Nakamura Chemical Co., Ltd.) were used. As a silane coupling agent, 3-methacryloxypropyltrimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared. As a radical generator, a peroxy ester (trade name: Perhexa 25O, manufactured by NOF CORPORATION, 1-minute half-life temperature: 118.8 ° C., 10-hour half-life temperature: 66.2 ° C.) was prepared. As the solder particles, Bi28Sn72 solder particles manufactured by Mitsui Mining & Smelting Co., Ltd. (Bi content 28% by mass, Sn content 72% by mass, average particle size 5 μm, trade name: ST-5 (composition of Bi28Sn72)) are used. did. The first endothermic peak and the second endothermic peak of the Bi28Sn72 solder particles in DSC were 139 ° C. and the second endothermic peak was 190 ° C.

The above material is phenoxy resin / isocyanuric acid EO-modified diacrylate / urethane acrylate / 2-methacryloyloxyethyl acid phosphate / silane coupling agent / radical generator in solid content mass of 50 g / 20 g / 20 g / 5 g / 3 g / 3 g. The mixture was mixed in a ratio to prepare an adhesive composition-containing liquid A. Further, 10 parts by mass of Bi28Sn72 solder particles (average particle size 5 μm) was added to 15 parts by mass of methyl ethyl ketone and sufficiently dispersed by ultrasonic waves to prepare a preparation liquid B. A circuit connection material-containing liquid (adhesive composition for circuit connection) was prepared by dispersing 25 parts by mass (10 parts by mass of solder particles) of the preparation liquid B with respect to 101 parts by mass of the adhesive composition-containing liquid A.

After applying the circuit connection material-containing liquid on a PET film having a thickness of 50 μm with one side surface-treated using a coating device, the PET film is dried with hot air at 70 ° C. for 3 minutes to form a PET film having a thickness of 25 μm and 35 μm. Film-shaped circuit connection materials were obtained respectively.

(Example 2)
In the same manner as in Example 1, except that P-2M was changed to PM-21 (a phosphoric acid ester containing an ethylenically unsaturated bond, manufactured by Nippon Kayaku Co., Ltd., product name) as the component (B). A film-shaped circuit connection material was produced.

(Example 3)
As the component (A), Bi28Sn72 solder particles are used as Bi58Sn42 solder particles (Bi content 58% by mass, Sn content 42% by mass, average particle size 5 μm, trade name: ST-5 (composition of Bi58Sn42), Mitsui Mining & Smelting Co., Ltd.). A film-shaped circuit connection material was produced in the same manner as in Example 1 except that the material was changed to (manufactured by Co., Ltd.). The first endothermic peak of the Bi58Sn42 solder particles was 139 ° C., and no secondary heat peak was present.

(Example 4)
A film-shaped circuit connection material was produced in the same manner as in Example 2 except that the Bi28Sn72 solder particles were changed to Bi58Sn42 solder particles as the component (A).

(Example 5)
3 parts by mass of polystyrene fine particles (trade name: PB-3006W, manufactured by Matsuura Co., Ltd., average particle size 6 μm) were prepared and dispersed in 7 parts by mass of a MEK / toluene mixed solution to obtain a dispersion liquid C. After mixing 101 parts by mass of the adhesive composition-containing liquid A and 25 parts by mass (10 parts by mass of solder particles) of the preparation liquid B in Example 2, 10 parts by mass of the dispersion liquid C (3 parts by mass of polystyrene fine particles). Part) was added and mixed to prepare a circuit connection material-containing liquid. Then, in the same manner as in Example 1, a film-shaped circuit connection material was produced.

(Comparative Example 1)
A film-shaped circuit connection material was produced in the same manner as in Example 1 except that P-2M was not used.

(Comparative Example 2)
A film-shaped circuit connection material was produced in the same manner as in Comparative Example 1 except that the Bi28Sn72 solder particles were changed to Bi58Sn42 solder particles as the component (A).

(Comparative Example 3)
As a flux, 5 parts by mass of propionic acid was dissolved in 45 parts by mass of ethanol, and this was added to the circuit connection material-containing liquid of Comparative Example 1. Then, in the same manner as in Example 1, a film-shaped circuit connection material was produced.

(Comparative Example 4)
A film-shaped circuit connection material was produced in the same manner as in Example 1 except that the Bi28Sn72 solder particles were changed to nickel particles having an average particle size of 5 μm (manufactured by Nikkoshi Co., Ltd., trade name: Ni123).

<Evaluation of connection resistance (evaluation of initial resistance and connection resistance after reliability test)>
(1) In the case of FPC (outermost layer Au plating) / PWB (outermost layer Au plating) connection A film-shaped circuit connection material (0.6 mm width) obtained by the above manufacturing method is used with a line width of 100 μm, a pitch of 200 μm, and a thickness of 35 μm. The copper circuit of No. 1 was allowed to stand on an FR-4 substrate (PWB) having 150 circuit electrodes subjected to Ni / Au plating treatment. A silicone cushion material with a thickness of 200 μm is laid on the PET film side, and a thermocompression bonding device (heating method: constant heat type, manufactured by Nikka Kikai Engineering Co., Ltd.) is used from the PET film side to reach a temperature of 70 ° C. and 1 MPa for 2 seconds. Was heated and pressurized. Then, the PET film was peeled off.

A flexible circuit board (FPC) having 150 circuit electrodes obtained by Ni / Au plating on a copper circuit having a line width of 100 μm, a pitch of 200 μm, and a thickness of 18 μm via the film-shaped circuit connection material from which the PET film has been peeled off. And the above FR-4 substrate (PWB) to a circuit connection area of 30,000 μm ² (per electrode) using a thermal crimping device (heating method: constant heat type, manufactured by JVC Gumy Plus Engineering Co., Ltd.). Then, a silicone cushion material having a thickness of 200 μm was laid, a tool was applied from the FPC side, and heating and pressurization was performed at an ultimate temperature of 160 ° C. and 5 MPa for 5 seconds to connect them over a width of 30 mm to prepare a circuit connection structure. At this time, a film-shaped circuit connection material having a thickness of 35 μm was used.

Next, the resistance per terminal of the connected circuit was measured by the 4-terminal method. The measured current was 1 mA, the measured voltage V (mV) was measured, and the connection resistance per connection terminal was calculated. Based on the calculated connection resistance, the initial resistance and the connection resistance after the reliability test were evaluated as follows.
Initial resistance (X): Among the measurement electrodes of the circuit connection structure having a plurality of circuit electrodes, the maximum value of the initial resistance was defined as X (Ω). Those having an X of 0.01 Ω or less were evaluated as “◯”, and those having an X of more than 0.01 Ω were evaluated as “×”.
Connection resistance (Y) after reliability test: The circuit connection structure was placed in an environment of 85 ° C. and 85% RH for 100 hours, and the connection resistance was measured. After that, among the measurement electrodes of the circuit connection structure having a plurality of circuit electrodes, the maximum value of the connection resistance was set to Y (Ω). The rate of increase in resistance (Z) = Y / X was evaluated as "A" when it was 3 or less, "B" when it was more than 3 and 5 or less, and "C" when it was more than 5. ..

(2) In the case of FPC (outermost layer Au plating) / FPC (outermost layer Au plating) The film-shaped circuit connection material (1.2 mm width) obtained by the above manufacturing method is used with a line width of 50 μm, a pitch of 100 μm, and a thickness of 12 μm. The copper circuit of No. 1 was allowed to stand on a first flexible circuit board (first FPC) having 300 circuit electrodes subjected to Ni / Au plating treatment. A silicone cushion material with a thickness of 200 μm is laid on the PET film side, and a thermocompression bonding device (heating method: constant heat type, manufactured by Nikka Kikai Engineering Co., Ltd.) is used from the PET film side to reach a temperature of 70 ° C. and 1 MPa for 2 seconds. Was heated and pressurized. Then, the PET film was peeled off.

A second flexible circuit board having 300 circuit electrodes obtained by Ni / Au plating on a copper circuit having a line width of 50 μm, a pitch of 100 μm, and a thickness of 12 μm via the film-shaped circuit connection material from which the PET film has been peeled off. (2nd FPC) and the above-mentioned 1st flexible circuit board (1st FPC) are connected to each other using a thermal crimping device (heating method: constant heat type, manufactured by Nikka Kikai Engineering Co., Ltd.) with a circuit connection area of 30,000 μm. In ² (per electrode), lay a silicone cushioning material with a thickness of 200 μm, apply a tool from the 2nd FPC side, heat and pressurize at an ultimate temperature of 160 ° C. and 5 MPa for 5 seconds, and connect over a width of 30 mm. A connection structure was prepared. At this time, a film-shaped circuit connection material having a thickness of 25 μm was used. The connection resistance evaluation method is the same as (1) above.

(3) In the case of connection of FPC (outermost layer Sn plating) / PWB (outermost layer Au plating) for COF The film-shaped circuit connection material (0.6 mm width) obtained by the above manufacturing method is used with a line width of 100 μm and a pitch of 200 μm. A copper circuit having a thickness of 35 μm was allowed to stand on an FR-4 substrate (PWB) having 150 circuit electrodes subjected to Ni / Au plating treatment. A silicone cushion material with a thickness of 200 μm is laid on the PET film side, and a thermocompression bonding device (heating method: constant heat type, manufactured by Nikka Kikai Engineering Co., Ltd.) is used from the PET film side to reach a temperature of 70 ° C. and 1 MPa for 2 seconds. Was heated and pressurized. Then, the PET film was peeled off.

A flexible circuit board (FPC for COF) having 150 circuit electrodes obtained by Sn-plating a copper circuit having a line width of 100 μm, a pitch of 200 μm, and a thickness of 8 μm via the film-shaped circuit connection material from which the PET film has been peeled off. And the above FR-4 substrate (PWB) to a circuit connection area of 30,000 μm ² (per electrode) using a thermal crimping device (heating method: constant heat type, manufactured by Nikka Kikai Engineering Co., Ltd.). Then, a silicone cushion material having a thickness of 200 μm was laid, a tool was applied from the FPC side for COF, and heating and pressurization was performed at an ultimate temperature of 160 ° C. and 5 MPa for 5 seconds to connect over a width of 30 mm to prepare a circuit connection structure. .. At this time, a film-shaped circuit connection material having a thickness of 35 μm was used. The connection resistance evaluation method is the same as (1) above.

(4) Connection of FPC for COF (Sn plating on the outermost layer) / FPC (Au plating on the outermost layer) The film-shaped circuit connection material (1.2 mm width) obtained by the above manufacturing method is used with a line width of 50 μm and a pitch of 100 μm. A copper circuit having a thickness of 12 μm was allowed to stand on a first flexible circuit board (FPC) having 300 circuit electrodes subjected to Ni / Au plating treatment. A silicone cushion material with a thickness of 200 μm is laid on the PET film side, and a thermocompression bonding device (heating method: constant heat type, manufactured by Nikka Kikai Engineering Co., Ltd.) is used from the PET film side to reach a temperature of 70 ° C. and 1 MPa for 2 seconds. Was heated and pressurized. Then, the PET film was peeled off.

A flexible circuit board (FPC for COF) having 300 circuit electrodes obtained by Sn-plating a copper circuit having a line width of 50 μm, a pitch of 100 μm, and a thickness of 8 μm via the film-shaped circuit connection material from which the PET film has been peeled off. And the above-mentioned first flexible circuit board (FPC), using a thermal crimping device (heating method: constant heat type, manufactured by Nikka Kikai Engineering Co., Ltd.), a circuit connection area of 30,000 μm ² (per electrode). ), Lay a silicone cushion material with a thickness of 200 μm, apply a tool from the FPC side for COF, heat and pressurize at an ultimate temperature of 160 ° C. and 5 MPa for 5 seconds, and connect over a width of 30 mm to form a circuit connection structure. Made. At this time, a film-shaped circuit connection material having a thickness of 25 μm was used. The connection resistance evaluation method is the same as (1) above.

Table 1 shows the results of the connection resistance evaluation (evaluation of the initial resistance and the connection resistance after the reliability test). In the table, the FPC for COF is represented by "COF", and the circuit connection material is represented by "ACF".

From the above, it was confirmed that in the examples, a circuit connection structure having a lower connection resistance and a small resistance increase even after the reliability test and stably showing a low resistance can be obtained as compared with the comparative example.

10 ... Printed circuit board (PWB), 20 ... Flexible circuit board (FPC), 30 ... Flexible circuit board for COF (FPC for COF), 11,21,31 ... Board, 12, 22, 32 ... Copper circuit, 13, 23 ... Ni plating layer, 33 ... Sn plating layer, 14, 24 ... Au plating layer, 15, 25, 35 ... circuit electrodes, 50 ... circuit connection members, 51 ... insulating material, 52 ... conductive particles, 100, 200, 300, 400 ... Structure.

Claims (7)

(A) Solder particles having a Bi content of 21 to 40 % by mass and a Sn content of 79 to 60 % by mass.
(B) Phosphate ester-based organic compounds and
(C) Radical polymerizable compound and
(D) Radical generator and
An adhesive composition for circuit connection. The circuit connection adhesive composition according to claim 1, wherein the (B) phosphate ester-based organic compound contains a monofunctional or polyfunctional phosphate ester-based (meth) acrylate monomer. (E) The adhesive composition for circuit connection according to claim 1 or 2 , further containing organic fine particles. The circuit connection adhesive composition according to any one of claims 1 to 3, wherein the radically polymerizable compound (C) contains isocyanuric acid EO-modified di (meth) acrylate. A structure comprising the circuit connection adhesive composition according to any one of claims 1 to 4 or a cured product thereof. With the first circuit member having the first circuit electrode,
A second circuit member with a second circuit electrode, and
A circuit connecting member arranged between the first circuit member and the second circuit member is provided.
The first circuit electrode and the second circuit electrode are electrically connected to each other.
A structure in which the circuit connecting member comprises the circuit connecting adhesive composition according to any one of claims 1 to 4 or a cured product thereof. The first circuit electrode is an electrode having an Au plating layer on the outermost surface.
The structure according to claim 6, wherein the second circuit electrode is an electrode having an Au plating layer or a Sn plating layer on the outermost surface.

Images