CN116529838A - Adhesive film for circuit connection, connection structure, and method for manufacturing same - Google Patents

Abstract

A circuit-connecting adhesive film comprising solder particles having an average particle diameter of 1 to 30 [ mu ] m and a C.V. value of the particle diameter of 20% or less, wherein the ratio of the thickness of the circuit-connecting adhesive film to the average particle diameter of the solder particles exceeds 1.0 and is less than 1.5, and the melting point of the solder particles is T _m T when heating at a heating rate of 10 ℃/min under a nitrogen atmosphere _m The curing rate at the temperature is more than 80 percent.

Description

Adhesive film for circuit connection, connection structure, and method for manufacturing same

Technical Field

The present invention relates to an adhesive film for circuit connection, a connection structure, and a method for manufacturing the same.

Background

The method of mounting the liquid crystal driving IC on the Glass panel for liquid crystal display can be roughly classified into two types, COG (Chip-on-Glass: flip-Chip) mounting and COF (Chip-on-Flex: flip-Chip) mounting. In COG mounting, for example, a liquid crystal driving IC is directly bonded to a glass panel using a film-like circuit connection adhesive (hereinafter referred to as "circuit connection adhesive film"). On the other hand, in COF mounting, for example, a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and these are bonded to a glass panel using an adhesive film for circuit connection.

However, with the recent high definition of liquid crystal display, the pitch and area of metal bumps as circuit electrodes of an IC for driving liquid crystal are gradually narrowed. Therefore, the conductive particles in the adhesive may flow out between adjacent circuit electrodes to cause a short circuit. This tendency is remarkable particularly in COG mounting. If the conductive particles flow out between the adjacent circuit electrodes, the number of conductive particles trapped between the metal bump and the glass panel decreases, and there is a possibility that connection failure occurs due to an increase in connection resistance between the opposing circuit electrodes.

As a method for solving these problems, a method of forming composite particles (insulating coated conductive particles) by attaching a plurality of insulating particles (sub particles) to the surface of conductive particles (master particles) has been proposed. For example, patent document 1 proposes a method of attaching spherical resin particles to the surfaces of conductive particles.

Technical literature of the prior art

Patent literature

Patent document 1: japanese patent No. 4773685

Disclosure of Invention

Technical problem to be solved by the invention

The main object of the present invention is to provide an adhesive film for circuit connection, which can ensure sufficient capturing rate of conductive particles and sufficient insulation between adjacent electrodes even if the insulating coated conductive particles are not used as described above.

Means for solving the technical problems

An aspect of the present invention relates to an adhesive film for circuit connection shown in the following [1 ].

[1]A circuit-connecting adhesive film comprising solder particles having an average particle diameter of 1 to 30 [ mu ] m and a C.V. value of the particle diameter of 20% or less, wherein the ratio of the thickness of the circuit-connecting adhesive film to the average particle diameter of the solder particles exceeds 1.0 and is less than 1.5, and wherein the melting point of the solder particles is T _m T when heating at a heating rate of 10 ℃/min under a nitrogen atmosphere _m The curing rate at the temperature is more than 80 percent.

According to the adhesive film for circuit connection of the above aspect, it is possible to ensure a sufficient capturing rate of conductive particles (solder particles) and a sufficient insulation property between adjacent electrodes. The term "capture rate" as used herein refers to the ratio of the number of conductive particles captured per unit area of the connection site to the number of conductive particles (solder particles) per unit area of the adhesive film for circuit connection.

However, in recent years, with development of a new technology called micro LED or the like, a circuit member having a low height of an electrode is used. In the case of using such a circuit member, the total height of the electrodes to be connected may be smaller than the particle diameter of the conductive particles used in the adhesive for circuit connection. As a result of the studies by the present inventors, it has been found that even when the above-described circuit-connecting adhesive (for example, circuit-connecting adhesive film) containing insulating coated conductive particles is used in the production of such a connection structure, it is difficult to achieve both a sufficient capturing rate and a sufficient insulating property. On the other hand, according to the adhesive film for circuit connection of the above aspect, even when the total value of the heights of the connected electrodes is smaller than the particle diameter of the conductive particles, it is possible to ensure a sufficient capturing rate of the conductive particles (solder particles) and a sufficient insulation property between the adjacent electrodes.

The adhesive film for circuit connection of the above aspect may be the adhesive film for circuit connection shown in the following [2] to [6 ].

[2] The adhesive film for circuit connection according to [1], which contains a polymerizable compound and a thermal polymerization initiator.

[3] The adhesive film for circuit connection according to [2], wherein the polymerizable compound is a cationically polymerizable compound, and the thermal polymerization initiator is a thermal cationic polymerization initiator.

[4] The adhesive film for circuit connection according to [3], wherein the polymerizable compound contains at least one selected from the group consisting of alicyclic epoxy compounds and oxetane compounds.

[5] The adhesive film for circuit connection according to any one of [1] to [4], wherein the melting point of the solder particles is 280 ℃ or lower.

[6] The adhesive film for circuit connection according to any one of [1] to [5], which is used for bonding a 1 st circuit member having a 1 st electrode and a 2 nd circuit member having a 2 nd electrode, and electrically connecting the 1 st electrode and the 2 nd electrode to each other, the total of the height of the 1 st electrode and the height of the 2 nd electrode being smaller than the average particle diameter of the solder particles.

Another aspect of the present invention relates to a connecting structure shown in the following [7 ].

[7] A connection structure is provided with: a 1 st circuit part having a 1 st electrode; a 2 nd circuit part having a 2 nd electrode electrically connected to the 1 st electrode; and a connecting portion electrically connecting the 1 st electrode and the 2 nd electrode to each other via a solder layer and bonding the 1 st circuit member and the 2 nd circuit member, the connecting portion comprising a cured product of the adhesive film for circuit connection of any one of [1] to [6 ].

The connection structure of the above aspect may be the connection structure shown in the following [8 ].

[8] The connection structure according to [7], wherein a total of the height of the 1 st electrode and the height of the 2 nd electrode is smaller than an average particle diameter of the solder particles.

Another aspect of the present invention relates to a method for producing a connection structure shown in the following [9 ].

[9] A method of manufacturing a connection structure, comprising the steps of: disposing the adhesive film for circuit connection of [1] to [6] between a surface of a 1 st circuit member having a 1 st electrode provided with the 1 st electrode and a surface of a 2 nd circuit member having a 2 nd electrode provided with the 2 nd electrode; and heating a laminate including the 1 st circuit member, the adhesive film for circuit connection, and the 2 nd circuit member in a state of being pressed in a thickness direction of the laminate, thereby electrically connecting the 1 st electrode and the 2 nd electrode to each other via a solder layer and bonding the 1 st circuit member and the 2 nd circuit member.

The method for producing the connection structure of the above aspect may be the method shown in [10] below.

[10] The method for producing a connection structure according to [9], wherein the total of the height of the 1 st electrode and the height of the 2 nd electrode is smaller than the average particle diameter of the solder particles.

Effects of the invention

According to the present invention, it is possible to provide an adhesive film for circuit connection capable of ensuring a sufficient capturing rate of conductive particles (solder particles) and also ensuring a sufficient insulation property between adjacent electrodes.

Drawings

Fig. 1 is a schematic cross-sectional view showing an embodiment of an adhesive film for circuit connection.

Fig. 2 is a schematic plan view showing an example of arrangement of conductive particles in the adhesive film for circuit connection of fig. 1.

Fig. 3 is a schematic plan view showing an example of arrangement of conductive particles in the adhesive film for circuit connection of fig. 1.

Fig. 4 is a schematic cross-sectional view of a substrate for manufacturing the adhesive film for circuit connection of fig. 1.

Fig. 5 is a diagram showing a modification of the cross-sectional shape of the recess of the base body of fig. 4.

Fig. 6 is a view showing a state in which solder particles are arranged in the concave portion of the base body in fig. 4.

Fig. 7 is a schematic cross-sectional view showing a step of the method for producing the adhesive film for circuit connection of fig. 1.

Fig. 8 is a schematic cross-sectional view showing a step of the method for producing the adhesive film for circuit connection of fig. 1.

Fig. 9 is a schematic cross-sectional view showing an embodiment of the connection structure.

Fig. 10 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a connection structure.

Detailed Description

Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments. In addition, as for the materials exemplified below, one kind may be used alone or two or more kinds may be used in combination unless otherwise specified. The content of each component in the composition means the total amount of a plurality of substances present in the composition, unless otherwise specified, in the case where the plurality of substances corresponding to each component are present in the composition. The numerical ranges shown in the "to" are ranges including the numerical values before and after the "to" as the minimum value and the maximum value, respectively. In the numerical ranges described in the present specification in stages, the upper limit value or the lower limit value of the numerical range in one stage may be replaced with the upper limit value or the lower limit value of the numerical range in another stage. In the numerical ranges 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 embodiment. In the present specification, "(meth) acrylate" means at least one of an acrylate and a methacrylate corresponding thereto. The same applies to other similar expressions such as "(meth) acryl".

Adhesive film for circuit connection

The adhesive film for circuit connection according to one embodiment is a thermosetting adhesive film, and contains, as conductive particles, solder particles having an average particle diameter of 1 to 30 μm and a c.v. value of 20% or less. Here, the term "circuit connection" means connection for circuit components (for example, mounting of a light emitting element). The adhesive film for circuit connection may or may not have anisotropic conductivity. That is, the circuit-connecting adhesive film may be an anisotropic conductive adhesive film or a non-anisotropic conductive (e.g., isotropic conductive) adhesive film. The term "anisotropic conductivity" as used herein means conduction in the pressing direction and insulation in the non-pressing direction. Next, an adhesive film for circuit connection according to an embodiment will be described with reference to fig. 1.

Fig. 1 is a view schematically showing a longitudinal section of an adhesive film for circuit connection according to an embodiment. The "longitudinal section" refers to a section (section in the thickness direction) substantially orthogonal to the main surface of the adhesive film for circuit connection. The adhesive film 10 for circuit connection shown in fig. 1 is composed of a thermosetting adhesive film 1 and solder particles 2 arranged in the adhesive film 1.

The adhesive film 1 includes a 1 st adhesive layer 3 and a 2 nd adhesive layer 4 provided on the 1 st adhesive layer 3. The 1 st adhesive layer 3 is a layer to which solder particles 2 are transferred in a method for producing an adhesive film 10 for circuit connection described later.

The solder particles 2 are arranged near the boundary S between the 1 st adhesive layer 3 and the 2 nd adhesive layer 4, and the boundary S is located at the divided portion between the adjacent solder particles 2, 2. In fig. 1, the surface of the solder particles 2 (the surface on the 2 nd adhesive layer 4 side) is exposed from the surface of the 1 st adhesive layer 3, but the entire solder particles 2 may be embedded in the 1 st adhesive layer 3.

In a longitudinal section of the adhesive film 10 for circuit connection, adjacent solder particles are arranged in a lateral direction in a state of being separated from each other. In other words, the adhesive film 10 for circuit connection is composed of a central region 10a in which solder particles 2 are separated from adjacent solder particles in a longitudinal section thereof and are formed in a row along a lateral direction, and surface side regions 10b, 10c in which the solder particles 2 are substantially absent. The term "transverse direction" as used herein refers to a direction (left-right direction in fig. 1) substantially parallel to the main surface of the adhesive film for circuit connection. Adjacent solder particles are arranged in a state of being separated from each other in the lateral direction, and can be confirmed by, for example, observing a longitudinal section of the adhesive film for circuit connection by a scanning electron microscope or the like.

The shortest distance (d 11 and d21 in fig. 1) from the surface of the solder particle 2 to the surface of the circuit-connecting adhesive film 10 (the surface 3a of the 1 st adhesive layer 3 on the side opposite to the 2 nd adhesive layer 4 and the surface 4a of the 2 nd adhesive layer 4 on the side opposite to the 1 st adhesive layer 3) may be 0.05 to 1.5 μm. If the shortest distances d11 and d21 are 0.05 μm or more, the binder resin can be satisfactorily filled between the circuit members after the press-bonding, and therefore the insulation properties of the circuit tend to be improved, and if the shortest distances d11 and d21 are 1.5 μm or less, the flow of the conductive particles during the press-bonding is suppressed, and high particle trapping properties tend to be obtained. The shortest distances d11 and d21 may be 0.1 μm or more and 0.2 μm or more and may be 1.4 μm or less and 1.2 μm or less. The shortest distance d11 may be the same as or different from the shortest distance d 21.

Fig. 2 and 3 are plan views schematically showing an example of arrangement of solder particles 2 in the adhesive film 10 for circuit connection. As shown in fig. 2 and 3, at least a part of the plurality of solder particles 2 may be arranged in a predetermined pattern when the adhesive film for circuit connection is viewed from above. In fig. 2, the solder particles 2 are arranged at regular and substantially uniform intervals throughout the entire area of the adhesive film 10 for circuit connection, but for example, as shown in fig. 3, the solder particles 2 may be arranged so that an area 10d in which a plurality of solder particles 2 are regularly arranged and an area 10e in which substantially no solder particles 2 are present are regularly formed when the adhesive film for circuit connection is viewed from above. The positions and the number of the solder particles 2 can be set according to, for example, the shape, size, pattern, and the like of the electrodes to be connected. At least a part of the plurality of solder particles are arranged in a predetermined pattern, and can be confirmed by, for example, observing the circuit-connecting adhesive film from above the main surface of the circuit-connecting adhesive film using an electron microscope or the like.

The ratio (monodispersion) of the solder particles 2 existing in a state separated from other solder particles 2 (monodispersed state) is preferably 90.0% or more, and may be 93.0% or more, 95.0% or more, 97.0% or more, or 98.0% or more. The upper limit of the monodispersity is 100%. The higher the monodispersity, the easier it is to obtain a connection structure excellent in insulation reliability. In the method for producing the adhesive film 10 for circuit connection described later, the dispersed state can be formed by using a substrate in which the solder particles 2 are arranged in a predetermined arrangement.

The adhesive film 10 for circuit connection has a thickness of more than 1.0 times and less than 1.5 times the average particle diameter of the solder particles 2. That is, the ratio of the thickness of the adhesive film 10 for circuit connection to the average particle diameter of the solder particles 2 exceeds 1.0 and is less than 1.5. In terms of further improving the capture rate of the solder particles 2 between the opposing electrodes and further improving the insulation resistance between the adjacent electrodes, the ratio of the thickness of the adhesive film 10 for circuit connection to the average particle diameter of the solder particles 2 may be 1.4 or less, 1.3 or less, 1.2 or less, or 1.1 or less. That is, the ratio of the thickness of the adhesive film 10 for circuit connection to the average particle diameter of the solder particles 2 may be more than 1.0 and 1.4 or less, more than 1.0 and 1.3 or less, more than 1.0 and 1.2 or less, or more than 1.0 and 1.1 or less. The thickness of the circuit-connecting adhesive film 10 is equal to the thickness of the adhesive film 1.

The thickness of the circuit-connecting adhesive film 10 may be, for example, 2.0 μm or more, 3.0 μm or more, or 4.0 μm or more, 10.0 μm or less, 8.0 μm or less, or 6.0 μm or less, and 2.0 to 10.0 μm, 3.0 to 8.0 μm, or 4.0 to 6.0 μm.

Regarding the adhesive film 10 for circuit connection, if the melting point of the solder particles is set to T _m T when heating at a heating rate of 10 ℃/min under a nitrogen atmosphere _m The curing rate at the temperature is more than 80 percent. In general, in manufacturing a connection structure using solder particles, after solder is melted to connect circuit components to each other, a sealing resin is cured. Therefore, in general, the melting point of solder particlesLower than the curing temperature of the binder component. However, if the thickness of the adhesive film 10 for circuit connection is smaller than 1.5 times the average particle diameter of the conductive particles, the amount of the adhesive component is reduced relative to the amount of the conductive particles, and therefore, when solder particles are used as the conductive particles, the solder that diffuses into the adhesive film 1 by thermocompression bonding at the time of connection may deteriorate the insulation (for example, short circuit is likely to occur). On the other hand, in the above-mentioned curable adhesive film 10 for circuit connection, the adhesive film 1 is cured before the solder particles 2 are melted by thermocompression bonding at the time of connection, and the diffusion of solder is suppressed, so that even if the thickness of the adhesive film 10 for circuit connection is less than 1.5 times the average particle diameter of the conductive particles, sufficient insulation between adjacent electrodes can be ensured. T under the above conditions from the viewpoint that the insulation between adjacent electrodes becomes better _m The curing rate at the temperature may be 85% or more, 90% or more, or 95% or more, or 100%.

Regarding the curing rate (T when heated at a heating rate of 10 ℃/min under nitrogen atmosphere) of the adhesive film 10 for circuit connection _m Cure rate at c), can be obtained using the amount of heat generated by measurement using a differential scanning calorimeter (Differential Scanning Calorimeter). Specifically, a differential scanning calorimeter was used to measure the heat in nitrogen (N ₂ ) The heat generation amount of the adhesive film 10 for circuit connection was measured at a temperature rising rate of 10 ℃/min under an atmosphere, and the heat generation amount (Q) from 50 ℃ until the adhesive film 10 for circuit connection was completely cured was obtained ₁ ) And a melting point T from 50 ℃ to the solder particles _m Heating value (Q) ₂ ) Then, the obtained value is substituted into the following formula (a), whereby the curing rate can be calculated. Find Q ₁ At the time, the change rate of the differential curve (DDSC curve) of the DSC curve obtained by the measurement was 0.01[ W.g. ] C]In the following cases, it is determined that the adhesive film 10 for circuit connection is completely cured.

Cure rate (%) =q ₂ /Q ₁ ×100(A)

The pressure-sensitive adhesive film 10 for circuit connection having the above-mentioned curing rate can be easily produced by one skilled in the art by using, for example, a compound having a cyclic ether group or the like as a thermosetting component, selection of the kind of a polymerization initiator, adjustment of the blending amount, or the like.

The adhesive film 10 for circuit connection having the above-described features is suitable for use in bonding a 1 st circuit member having a 1 st electrode to a 2 nd circuit member having a 2 nd electrode and electrically connecting the 1 st electrode and the 2 nd electrode to each other. In particular, the adhesive film 10 for circuit connection contains solder particles as conductive particles, and has a thickness of 1.0 times to less than 1.5 times the average particle diameter of the solder particles 2, and is therefore suitable for mounting under low pressure (for example, 5MPa or less based on the area of the circuit component having a small bonding area among the 1 st circuit component or the 2 nd circuit component).

According to the adhesive film for circuit connection 10, it is possible to ensure a sufficient capturing rate of conductive particles (solder particles) and a sufficient insulation property between adjacent electrodes. In particular, when the total value of the heights of the connected electrodes (the total value of the heights of the 1 st electrode and the 2 nd electrode) is smaller than the average particle diameter of the solder particles, the above effect becomes remarkable. Further, according to the adhesive film 10 for circuit connection, a sufficiently low connection resistance tends to be obtained.

The adhesive film 1 and the solder particles 2 will be described in detail below.

(adhesive film)

The adhesive film 1 is, for example, an insulating adhesive film made of a material (insulating resin or the like) having no conductivity. The 1 st adhesive layer 3 and the 2 nd adhesive layer 4 constituting the adhesive film 1 are each composed of a thermosetting adhesive composition. Hereinafter, the adhesive composition constituting the 1 st adhesive layer 3 is referred to as "1 st adhesive composition" and the adhesive composition constituting the 2 nd adhesive layer 4 is referred to as "2 nd adhesive composition" as the case may be.

The adhesive composition (1 st adhesive composition and 2 nd adhesive composition) contains at least a thermosetting component. The thermosetting component is a component that can flow and cure by heating at the time of joining. The adhesive composition may contain a polymerizable compound and a thermal polymerization initiator as thermosetting components. The polymerizable compound may be a cationically polymerizable compound, and the thermal polymerization initiator may be a thermal cationic polymerization initiator, in view of the further excellent effect of reducing the connection resistance.

[ cationically polymerizable Compound ]

The cation polymerizable compound may be a compound having a cyclic ether group in view of further improving the effect of reducing the connection resistance and further improving the connection reliability. In the case of using at least 1 selected from the group consisting of alicyclic epoxy compounds and oxetane compounds among compounds having a cyclic ether group, the effect of reducing the connection resistance tends to be further improved. The cationically polymerizable compound may contain both an alicyclic epoxy compound and an oxetane compound from the viewpoint of easily obtaining a desired melt viscosity.

The alicyclic epoxy compound is not particularly limited as long as it is a compound having an alicyclic epoxy group (for example, epoxycyclohexyl group). Examples of the commercially available alicyclic epoxy compounds include EHPE3150, EHPE3150CE, and CELLOXIDE2021P, CELLOXIDE2081 (trade name, manufactured by Daicel Corporation), in addition to CELLOXIDE8010 (trade name, manufactured by bis-7-oxabicyclo [4.1.0] heptane, daicel Corporat ion). These may be used alone or in combination of 1 or more.

The oxetane compound is not particularly limited as long as it is a compound having an oxetanyl group. Examples of commercial products of oxetane compounds include ETERNACOLL OXBP (trade name, 4' -bis [ (3-ethyl-3-oxetanyl) methoxymethyl ] biphenyl, manufactured by UBE INDUSTRIES, LTD.), OXSQ, OXT-121, OXT-221, OXT-101, OXT-212 (trade name, TOAGOSEI CO., manufactured by LTD.) and the like. These may be used alone or in combination of 1 or more.

As the compound having a cyclic ether group, an epoxy compound other than an alicyclic epoxy compound may be used. Specifically, for example, an epoxy compound having an aromatic hydrocarbon group such as bisphenol a epoxy resin or bisphenol F epoxy resin (for example, the trade name "jER1010" manufactured by Mitsubishi Chemical Corporatio n) can be used. In view of further improving the effect of reducing the connection resistance and further improving the connection reliability, an epoxy compound having an aromatic hydrocarbon group may be used in combination with an alicyclic epoxy compound.

[ thermal cationic polymerization initiator ]

The thermal cationic polymerization initiator is, for example, a compound capable of starting polymerization by generating an acid or the like by heating (thermal latent cationic initiator). The thermal cationic polymerization initiator may be a salt compound composed of a cation and an anion. Examples of the thermal cationic polymerization initiator include a initiator having BF ₄ ^- 、BR ₄ ^- (R represents a phenyl group substituted with 2 or more fluorine atoms or 2 or more trifluoromethyl groups), PF ₆ ^- 、SbF ₆ ^- 、AsF ₆ ^- Sulfonium salts, phosphonium salts, ammonium salts, diazonium salts, iodonium salts, anilinium salts, pyridinium salts, and the like of the plasma anions. These may be used alone or in combination of 1 or more.

From the viewpoint of rapid curability, the thermal cationic polymerization initiator may be, for example, a salt compound having an anion containing boron as a constituent element. Examples of such a salt compound include a compound having BF ₄ ^- Or BR ₄ ^- (R represents a phenyl group substituted with 2 or more fluorine atoms or 2 or more trifluoromethyl groups). The anion containing boron as a constituent element may be BR ₄ ^- More specifically, it may be a tetrakis (pentafluorophenyl) borate.

From the viewpoint of storage stability, the thermal cationic polymerization initiator may be a salt compound having a cation represented by the following formula (I) or the following formula (II).

In the formula (I), R ¹ R is R ² Each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an organic group containing a substituted or unsubstituted aromatic hydrocarbon group, R ³ Represents an alkyl group having 1 to 6 carbon atoms.

The salt compound having a cation represented by the formula (I) may be an aromatic sulfonium salt compound (aromatic sulfonium salt type thermal acid initiator) in view of both storage stability and low-temperature activity. Namely, R in the formula (I) ¹ R is R ² At least one of them may be an organic group containing a substituted or unsubstituted aromatic hydrocarbon group. The anion in the salt compound having a cation represented by the formula (I) may be an anion containing antimony as a constituent element, and for example, may be hexafluoroantimonate (hexafluoroantimonic acid).

Specific examples of the compound having a cation represented by the formula (I) include 1-naphthylmethyl-p-hydroxyphenylsulfonium hexafluoroantimonate (SANSHIN CHEMICAL inhibitor co., ltd. Manufactured, SI-60 base), and the like.

In the formula (II), R ⁴ R is R ⁵ Each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an organic group containing a substituted or unsubstituted aromatic hydrocarbon group, R ⁶ R is R ⁷ Each independently represents an alkyl group having 1 to 6 carbon atoms.

The salt compound having a cation represented by the formula (II) (quaternary ammonium salt type thermal acid initiator) has resistance against a substance that may cause curing inhibition against cationic curing, and thus may be, for example, an aniline salt compound. Namely, R in the formula (II) ⁴ R is R ⁵ At least one of them may be an organic group containing a substituted or unsubstituted aromatic hydrocarbon group. Examples of the aniline salt compound include N, N-dialkylaniline salts such as N, N-dimethylaniline salt and N, N-diethylaniline salt. The anion in the salt compound having a cation represented by the formula (II) may be an anion containing boron as a constituent element, and for example, may be tetrakis (pentafluorophenyl) borate.

The compound having a cation represented by formula (II) may be an aniline salt having an anion containing boron as a constituent element. Examples of commercial products of such salt compounds include CXC-1821 (trade name, manufactured by King Industries, inc.), and the like.

The content of the thermal cationic polymerization initiator may be, for example, 0.1 to 20 parts by mass, 1 to 18 parts by mass, 3 to 15 parts by mass, or 5 to 12 parts by mass, relative to 100 parts by mass of the cationically polymerizable compound, in terms of securing the formability and curability of the adhesive film. In addition, the content of the thermal cationic polymerization initiator in the 1 st adhesive composition (based on 100 parts by mass of the cationic polymerizable compound in the 1 st adhesive composition) may be within the above-mentioned range, and the content of the thermal cationic polymerization initiator in the 2 nd adhesive composition (based on 100 parts by mass of the cationic polymerizable compound in the 2 nd adhesive composition) may be within the above-mentioned range.

From the viewpoint of ensuring curability of the adhesive film, the content of the thermosetting component (for example, the total content of the polymerizable compound and the thermal polymerization initiator) may be, for example, 5 mass% or more, 10 mass% or more, 15 mass% or more, or 20 mass% or more based on the total mass of the adhesive composition. The content of the thermosetting component may be, for example, 70 mass% or less, 60 mass% or less, 50 mass% or less, or 40 mass% or less based on the total mass of the adhesive composition in terms of ensuring the formability of the adhesive film. From these viewpoints, the content of the thermosetting component may be, for example, 5 to 70 mass%, 10 to 60 mass%, 15 to 50 mass%, or 20 to 40 mass% based on the total mass of the adhesive composition. In addition, the content of the thermosetting component in the 1 st adhesive composition (based on the total mass of the 1 st adhesive composition) may be within the above-mentioned range, and the content of the thermosetting component in the 2 nd adhesive composition (based on the total mass of the 2 nd adhesive composition) may be within the above-mentioned range. Hereinafter, similarly, the content of each component contained in the adhesive composition (based on the total mass of the adhesive composition) can be modified as the content of the thermosetting component in the 1 st adhesive composition (based on the total mass of the 1 st adhesive composition), and also as the content of the thermosetting component in the 2 nd adhesive composition (based on the total mass of the 2 nd adhesive composition).

[ other Components ]

The adhesive composition (1 st adhesive composition and 2 nd adhesive composition) may contain, for example, a thermoplastic resin, a filler, a coupling agent, and the like in addition to the thermosetting component.

The thermoplastic resin contributes to improving the film formability of the adhesive film. Examples of the thermoplastic resin include phenoxy resin, polyester resin, polyamide resin, polyurethane resin, polyester amine ester resin, acrylic rubber, and epoxy resin (solid at 25 ℃). Examples of the phenoxy resin include fluorene type phenoxy resin and bisphenol a/bisphenol F copolymerized phenoxy resin. These may be used alone or in combination of 1 or more.

The weight average molecular weight (Mw) of the thermoplastic resin may be, for example, 5000 to 200000, 10000 to 100000, 20000 to 80000, or 40000 to 60000 from the viewpoint of resin exclusivity at the time of mounting. The Mw is a value measured by Gel Permeation Chromatography (GPC) and converted using a ken line based on standard polystyrene.

The content of the thermoplastic resin may be, for example, 1 mass% or more, 5 mass% or more, 10 mass% or more, or 20 mass% or more, 70 mass% or less, 60 mass% or less, 50 mass% or less, or 40 mass% or less, and may be 1 to 70 mass%, 5 to 60 mass%, 10 to 50 mass%, or 20 to 40 mass%, based on the total mass of the adhesive composition.

As the filler, for example, a nonconductive filler (for example, nonconductive particles) is cited. The filler may be any of an inorganic filler and an organic filler. Examples of the inorganic filler include metal oxide particles such as silica particles, alumina particles, silica-alumina particles, titania particles, and zirconia particles; inorganic particles such as metal nitride particles. Examples of the organic filler include organic particles such as silicone particles, methacrylate-butadiene-styrene particles, acrylic-silicone particles, polyamide particles, and polyimide particles. These may be used alone or in combination of 1 or more. The filler material may be, for example, silica particles. The filler may be contained in an amount of, for example, 0.1 to 10 mass% based on the total mass of the adhesive composition.

Examples of the coupling agent include silane coupling agents having an organic functional group such as a (meth) acryloyl group, a mercapto group, an amino group, an imidazolyl group, and an epoxy group (such as γ -glycidoxypropyl trimethoxysilane), silane compounds such as tetraalkoxysilane, tetraalkoxy titanate derivatives, and polydialkyl titanate derivatives. These may be used alone or in combination of 1 or more. The adhesion can be further improved by the binder composition containing a coupling agent. The content of the coupling agent may be, for example, 0.1 to 10 mass% based on the total mass of the adhesive composition.

The adhesive composition (the 1 st adhesive composition and the 2 nd adhesive composition) may further contain other additives such as softeners, accelerators, degradation inhibitors, colorants, flame retardants, thixotropic agents, and the like as other components. The content of the other additives may be, for example, 0.1 to 10 mass% based on the total mass of the adhesive composition.

The 1 st adhesive composition and the 2 nd adhesive composition may contain the same components as each other or may contain different components from each other.

In terms of transferability of the solder particles 2 when the circuit-connecting adhesive film 10 is manufactured, the thickness d1 (distance indicated by d1 in fig. 1) of the 1 st adhesive layer 3 may be, for example, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more. The thickness d1 of the 1 st adhesive layer 3 may be, for example, 5.0 μm or less, 4.0 μm or less, or 3.0 μm or less from the viewpoint of being able to further efficiently capture solder particles at the time of connection. From these viewpoints, the thickness d1 of the 1 st adhesive layer 3 may be, for example, 0.5 to 5.0 μm, 1.0 to 4.0 μm, or 2.0 to 3.0 μm.

The thickness d2 (the distance denoted by d2 in fig. 1) of the 2 nd adhesive layer 4 may be set appropriately according to the height of the electrodes of the circuit member to be connected, etc., so that the space between the electrodes can be sufficiently filled to seal the electrodes, and from the viewpoint of obtaining a more excellent connection reliability, the thickness d2 of the 2 nd adhesive layer 4 may be, for example, 0.5 μm or more, 1.0 μm or more, 2.0 μm or more, 10 μm or less, 5.0 μm or less, 4.0 μm or less, or 3.0 μm or less, and may be 0.5 to 10 μm, 0.5 to 5.0 μm, 1.0 to 4.0 μm, or 2.0 to 3.0 μm.

The thickness d1 of the 1 st adhesive layer 3 and the thickness d2 of the 2 nd adhesive layer are obtained, for example, by: the adhesive film 10 for circuit connection was sandwiched by 2 pieces of glass (thickness: about 1 mm), injection-molded with a resin composition composed of 100g of bisphenol A type epoxy resin (trade name: manufactured by jER811, mitsubishi Chemical Corporation) and 10g of curing agent (trade name: epomount curing agent manufactured by Refine Tec Ltd.), cross-section ground with a grinder, and measured with a scanning electron microscope (SEM, trade name: manufactured by SE-8020,Hitachi High-Tech Science Corpor ation).

(solder particles)

The solder particles have, for example, a melting point lower than the joining temperature. Therefore, the solder particles are melted and fixed to the electrode by thermocompression bonding at the time of connection. Thereby, the opposing electrodes are electrically connected to each other. In view of being able to be mounted at a low temperature, the melting point of the solder particles may be 280 ℃ or lower, 220 ℃ or lower, 180 ℃ or lower, 160 ℃ or lower, or 140 ℃ or lower, for example. The melting point of the solder particles is, for example, 100 ℃ or higher.

From the viewpoint of both the connection strength and the low melting point, the solder particles may contain at least one selected from the group consisting of tin, tin alloy, indium, and indium alloy.

As the tin alloy, for example, in-Sn alloy, in-Sn-Ag alloy, sn-Au alloy, sn-Bi-Ag alloy, sn-Ag-Cu alloy, sn-Cu alloy, or the like can be used. Specific examples of these tin alloys include the following.

In-Sn (In 52 mass%, sn48 mass%, melting point 118 ℃ C.)

In-Sn-Ag (In 20 mass%, sn77.2 mass%, ag2.8 mass%, melting point 175 ℃ C.)

Sn-Bi (Sn 43 mass%, bi57 mass%, melting point 138 ℃ C.)

Sn-Bi-Ag (42% by mass of Sn, 57% by mass of Bi, 1% by mass of Ag, melting point 139 ℃ C.) Sn-Ag-Cu (96.5% by mass of Sn, 3% by mass of Ag, 0.5% by mass of Cu, melting point 217 ℃ C.)

Sn-Cu (Sn99.3 mass%, cu0.7 mass%, melting point 227 ℃ C.)

Sn-Au (Sn21.0 mass%, au79.0 mass%, melting point 278 ℃ C.)

As the indium alloy, for example, an in—bi alloy, an in—ag alloy, or the like can be used. Specific examples of these indium alloys include the following.

In-Bi (In66.3 mass%, bi33.7 mass%, melting point 72 ℃ C.)

In-Bi (In33.0 mass%, bi67.0 mass%, melting point 109 ℃ C.)

In-Ag (In97.0 mass%, ag3.0 mass%, melting point 145 ℃ C.)

In addition, the above-described indium alloy containing tin is classified as a tin alloy.

The solder particles may contain at least one selected from the group consisting of In-Bi alloy, in-Sn-Ag alloy, sn-Au alloy, sn-Bi-Ag alloy, sn-Ag-Cu alloy, and Sn-Cu alloy In terms of higher reliability at the time of high temperature and high humidity test and at the time of thermal shock test.

The tin alloy or indium alloy may be selected according to the use of the solder particles (temperature at the time of use), and the like. For example, when the solder particles are used for soldering at low temperature, if an in—sn alloy or an sn—bi alloy is used, soldering can be performed at a temperature of 150 ℃. In the case of using a material having a high melting point such as a Sn-Ag-Cu alloy or a Sn-Cu alloy, high reliability can be maintained even after being left at a high temperature.

The solder particles may include one or more selected from Ag, cu, ni, bi, zn, pd, pb, au, P and B. When the solder particles contain Ag or Cu, the melting point of the solder particles can be reduced to about 220 ℃ and the bonding strength with the electrode can be further improved, so that better conduction reliability can be easily obtained.

The Cu content of the solder particles is, for example, 0.05 to 10 mass%, and may be 0.1 to 5 mass% or 0.2 to 3 mass%. When the Cu content is 0.05 mass% or more, better solder connection reliability is easily achieved. When the Cu content is 10 mass% or less, the melting point is low, and the solder particles are easily formed with excellent wettability, and as a result, the connection reliability of the joint portion by the solder particles is easily improved.

The Ag content of the solder particles is, for example, 0.05 to 10% by mass, and may be 0.1 to 5% by mass or 0.2 to 3% by mass. When the Ag content is 0.05 mass% or more, better solder connection reliability is easily achieved. When the Ag content is 10 mass% or less, the melting point is low, and the solder particles are easily formed with excellent wettability, and as a result, the connection reliability of the joint portion by the solder particles is easily improved.

The solder particles may have a planar portion at a portion of the surface thereof. In the case of using such solder particles, the planar portion of the solder particles contacts the electrode, and thus a large contact area can be ensured between the planar portion and the electrode. When an electrode made of a material which is easily spread by wetting with solder and an electrode made of a material which is not easily spread by wetting with solder are connected, the connection between the two electrodes can be appropriately performed by adjusting the planar portion of the solder particles to be disposed on the electrode side of the latter. The surface of the solder particle other than the plane portion may have a spherical cap shape. That is, the solder particles may be curved surfaces having a planar surface portion and a spherical cap shape. Specifically, the solder particles may have a shape in which a plane portion having a diameter B is formed on a part of the surface of the ball having a diameter a. When such solder particles are used, more excellent conduction reliability and insulation reliability are easily obtained.

In the case where the solder particles have a shape in which a flat portion having a diameter B is formed on a part of the surface of the ball having a diameter a, the ratio (B/a) of the diameter B of the flat portion to the diameter a of the solder particles may be, for example, more than 0.01 and less than 1.0 (0.01 < B/a < 1.0), or may be 0.1 to 0.9 from the viewpoint of achieving more excellent conduction reliability and insulation reliability. The diameter a of the solder particles and the diameter B of the flat surface portion can be observed by, for example, a scanning electron microscope. Specifically, arbitrary solder particles are observed by a scanning electron microscope, and an image is taken. The diameter A of the solder particles and the diameter B of the flat surface portion were measured from the obtained image, and the B/A of the particles was obtained. This operation was performed on 300 solder particles and an average value was calculated as the B/a of the solder particles.

When a quadrangle circumscribed with the projection image of the solder particle is formed by two pairs of parallel lines, if the distance between the opposing sides is X and Y (where Y < X), the ratio of Y to X (Y/X) may be more than 0.8 and 1.0 or less (0.8 < Y/X. Ltoreq.1.0), or may be more than 0.8 and less than 1.0 or 0.81 to 0.99, respectively. Such solder particles can be referred to as particles that are closer to spheres. If the solder particles have a shape close to a sphere, the solder particles tend to be easily accommodated in the concave portion of the base in a manufacturing method described later. In addition, since the solder particles have a shape close to a sphere, when the electrodes are electrically connected to each other via the solder layer, unevenness is less likely to occur in contact between the solder particles and the electrodes, and stable connection tends to be obtained. The projection image of the solder particles can be obtained by observing arbitrary solder particles with a scanning electron microscope, for example. When Y/X is obtained, two pairs of parallel lines are drawn on the obtained projection image, one pair of parallel lines is arranged at a position where the distance between the parallel lines is the smallest, and the other pair of parallel lines is arranged at a position where the distance between the parallel lines is the largest. This operation was performed on 300 solder particles, and an average value of Y/X was calculated as Y/X of the solder particles.

The average particle diameter of the solder particles is 1-30 mu m. The average particle diameter of the solder particles may be 2 μm or more or 4 μm or more from the viewpoint of easy obtaining of excellent conductivity. The average particle diameter of the solder particles may be 25 μm or less or 20 μm or less from the viewpoint of easy obtaining of better connection reliability with the micro-sized electrode. From these viewpoints, the average particle diameter of the solder particles may be 2 to 25 μm or 4 to 20 μm.

The average particle diameter of the solder particles can be measured using various methods corresponding to the size. For example, methods such as dynamic light scattering, laser diffraction, centrifugal sedimentation, electrical detection zone, and resonance type mass measurement can be used. Further, a method of measuring the particle size from an image obtained by an optical microscope, an electron microscope, or the like can be utilized. Specific examples of the apparatus include a flow type particle image analyzer, a microtrac, and a coulter counter. The particle diameter of the non-spherical solder particles may be the diameter of a circle circumscribing the solder particles in the SEM image.

The C.V. value of the particle diameter of the solder particles is 20% or less. The c.v. value of the particle diameter is a value calculated by multiplying a value obtained by dividing the standard deviation of the particle diameter of the solder particles by the average particle diameter by 100, and is a parameter indicating the degree of deviation of the particle diameter of the solder particles. A small c.v. value of the particle diameter of the solder particles means that the variation in the particle diameter of the solder particles is small. The standard deviation of the particle diameter of the solder particles was measured by the same method as the method for measuring the average particle diameter of the solder particles described above. The c.v. value of the particle diameter of the solder particles may be 10% or less, 9% or less, 8% or less, 7% or less, or 5% or less from the viewpoint of enabling more excellent conductive reliability and insulation reliability. The lower limit of the c.v. value of the particle diameter of the solder particles is not particularly limited, and may be, for example, 0.1% or more, 1% or more, or 2% or more. That is, the C.V. value of the particle diameter of the solder particles may be 0.1 to 20%, 1 to 10%, 2 to 9%, 2 to 8%, etc.

The content of the solder particles may be, for example, 40 mass% or more, 50 mass% or more, or 60 mass% or more based on the total mass of the adhesive film for circuit connection, in terms of further improving the conductivity. The content of the solder particles may be, for example, 80 mass% or less, 75 mass% or less, or 70 mass% or less based on the total mass of the adhesive film for circuit connection, from the viewpoint of easy suppression of short-circuiting. From these viewpoints, the content of the solder particles may be, for example, 40 to 80 mass%, 50 to 75 mass%, or 60 to 70 mass% based on the total mass of the adhesive film for circuit connection.

The solder particles in the adhesive film 10 for circuit connection may have a particle density of 100 pieces/mm from the viewpoint of obtaining stable connection resistance ² Above mentioned1000 pieces/mm ² Above 3000 pieces/mm ² Above or 5000 pieces/mm ² The above. The particle density of the solder particles in the adhesive film 10 for circuit connection may be 100000 pieces/mm from the viewpoint of improving the insulation between adjacent electrodes ² Below 70000 pieces/mm ² Below 50000 pieces/mm ² Below or 30000 pieces/mm ² The following is given.

Method for producing adhesive film for circuit connection

The adhesive film 10 for circuit connection can be produced, for example, by a method comprising the steps of: a step (preparation step) of preparing a substrate having a plurality of solder particles 2 arranged on a surface thereof (for example, a substrate having a plurality of recesses on a surface thereof and at least a part of the plurality of recesses being arranged with solder particles 2); a step (transfer step) of transferring solder particles to the 1 st adhesive layer 3 by providing the 1 st adhesive layer 3 on the surface (for example, a surface on which a recess is formed) of the base; and a step (lamination step) of providing the 2 nd adhesive layer 4 on one surface of the 1 st adhesive layer 3. According to this method, by using a substrate in which solder particles are arranged in a predetermined arrangement, the adhesive film 10 for circuit connection having a predetermined arrangement and also excellent in monodispersity can be obtained.

Hereinafter, a method for producing the adhesive film 10 for circuit connection will be described with reference to fig. 4 to 8. Fig. 4 is a schematic view showing a longitudinal section of a substrate used in the method for manufacturing the adhesive film 10 for circuit connection, fig. 5 is a view showing a modification of the cross-sectional shape of the concave portion of the substrate of fig. 4, fig. 6 is a schematic view showing a state in which solder particles 2 are arranged in the concave portion of the substrate of fig. 4, fig. 7 is a schematic view showing an example of a preparation process, and fig. 8 is a schematic view showing an example of a transfer process. In the method described below, a substrate having a plurality of recesses on the surface and solder particles 2 disposed in at least a part of the plurality of recesses is used, but the present invention is not limited to such a substrate, and for example, a substrate having a support portion (needle or the like) on the surface to which solder particles can be fixed may be used.

(preparation step)

In the preparation step, first, a substrate 6 having a plurality of recesses 7 on the surface thereof is prepared (see fig. 4). The base body 6 has a plurality of recesses 7. The plurality of concave portions 7 are arranged regularly in a predetermined pattern (for example, a pattern corresponding to an electrode pattern of the circuit member), for example. When the concave portions 7 are arranged in a predetermined pattern, the solder particles 2 are transferred to the 1 st adhesive layer in a predetermined pattern. Thus, the adhesive film 10 for circuit connection in which the solder particles 2 are regularly arranged in a predetermined pattern (such as the pattern shown in fig. 2 and 3) can be obtained.

As shown in fig. 4, the recess 7 of the base 6 may be formed in a tapered shape in which an opening area is enlarged from the bottom 7a side of the recess 7 toward the surface 6a side of the base 6, for example. That is, the width of the bottom 7a of the recess 7 (width a in fig. 4) may be narrower than the width of the opening of the recess 7 (width b in fig. 4). The dimensions (width a, width b, volume, taper angle, depth, etc.) of the recess 7 can be set according to the size of the target solder particle and the position of the solder particle in the adhesive film for circuit connection. For example, the width (width b) of the opening of the recess 7 may be larger than the maximum particle diameter of the solder particle 2 or smaller than 2 times the maximum particle diameter of the solder particle.

The shape of the recess 7 (the cross-sectional shape of the recess 7) in the longitudinal section of the base 6 may be, for example, a shape as shown in fig. 5 (a) to (h). Any of the cross-sectional shapes shown in fig. 5 (a) to (h) is such that the width (width b) of the opening of the recess 7 is the largest width among the cross-sectional shapes. This facilitates removal of the solder particles disposed in the recess 7, and improves workability.

The shape of the opening of the recess 7 may be circular, elliptical, triangular, quadrangular, polygonal, or the like.

The recess 7 of the base 6 can be formed by a known method such as photolithography and machining. In these methods, the size and shape of the recess can be freely designed.

As a material constituting the substrate 6, for example, inorganic materials such as silicon, various ceramics, glass, metal such as stainless steel, and organic materials such as various resins can be used. As described later, in the manufacturing method of the present embodiment, the solder particles 2 can be arranged in the recess 7 of the base 6 by forming the solder particles 2 in the recess 7 of the base 6, but in this case, the base 6 may have heat resistance that does not deteriorate at the melting temperature of the fine particles for forming the solder particles 2.

Next, the solder particles 2 are disposed (housed) in at least a part (a part or all) of the plurality of recesses 7 of the base 6 (see fig. 6).

The arrangement method of the solder particles 2 is not particularly limited. The configuration method may be either dry or wet. For example, by disposing the solder particles 2 on the surface 6a of the base 6 and scraping the surface 6a of the base 6 with a squeegee or a micro-adhesive roller, the solder particles 2 can be disposed in the concave portion 7 while removing the excessive solder particles 2. When the width b of the opening of the recess 7 is larger than the depth of the recess 7, solder particles may fly out of the opening of the recess 7. When the squeegee is used, the solder particles flying out from the opening of the recess 7 are removed. As a method for removing the excessive solder particles, there is a method of blowing compressed air and scraping the surface 6a of the substrate 6 with a nonwoven fabric or a fiber bundle. These methods are preferable in terms of handling easily deformable particles (e.g., solder particles) as solder particles because they are weaker in physical force than the squeegee.

In the method for manufacturing the adhesive film 10 for circuit connection, the solder particles 2 can be arranged in the concave portion 7 by forming the solder particles 2 in the concave portion 7 of the base 6. Specifically, for example, as shown in fig. 7, after the particles 8 for forming the solder particles 2 are accommodated in the recess 7, the particles 8 accommodated in the recess 7 are fused, whereby the solder particles 2 can be formed in the recess 7. The fine particles 8 stored in the recess 7 are melted and integrated, and are spherical by surface tension, but at this time, in the contact portion with the bottom 7a of the recess 7, the melted metal takes a shape following the bottom 7 a. Therefore, for example, in the case where the bottom 7a of the recess 7 has a flat shape as shown in fig. 7, the solder particles 2 have a flat portion 2a at a part of the surface.

The fine particles 8 may be accommodated in the concave portion 7, and the variation in the particle size distribution may be large, or the shape may be deformed.

As a method of melting the fine particles 8 accommodated in the recess 7, there is a method of heating the fine particles 8 to a temperature equal to or higher than the melting point of the material (solder) forming the fine particles. The particles 8 may not be melted, wet-spread or both of them even when heated at a temperature equal to or higher than the melting point due to the influence of the oxide film. Therefore, the microparticles 8 are exposed to a reducing atmosphere, and after removing the oxide film on the surface of the microparticles 8, the microparticles 8 are heated to a temperature equal to or higher than the melting point of the microparticles 8, whereby the microparticles 8 can be melted, wet-spread, and the combination thereof can be achieved. From the same point of view, the melting of the fine particles 8 may be performed under a reducing atmosphere.

The method of setting to the reducing atmosphere is not particularly limited as long as the above-described effects can be obtained, and there are methods using hydrogen gas, hydrogen radicals, formic acid gas, and the like, for example. For example, the fine particles 8 can be melted in a reducing atmosphere by using a hydrogen reducing furnace, a hydrogen radical reducing furnace, a formic acid reducing furnace, or a conveyor furnace or a continuous furnace of these. These devices can be provided with a heating device, a chamber filled with an inert gas (nitrogen gas, argon gas, or the like), a mechanism for setting the chamber to a vacuum, or the like in the furnace, whereby the reducing gas can be controlled more easily. Further, if the chamber can be evacuated, the fine particles 8 can be melted and combined, and then the voids can be removed by reducing the pressure, so that the solder particles 2 having further excellent connection stability can be obtained.

The configuration file such as reduction, dissolution conditions, temperature, and adjustment of the furnace atmosphere of the fine particles 8 can be appropriately set in consideration of the melting point, particle size, size of the concave portion, material of the substrate 6, and the like of the fine particles 8.

According to the above method, the solder particles 2 having a substantially uniform size can be formed regardless of the material and shape of the fine particles 8. Since the size and shape of the solder particles 2 depend on the amount of the fine particles 8 stored in the recess 7, the shape of the recess 7, and the like, the size and shape of the solder particles 2 can be freely designed by designing the recess 7 (adjusting the size, shape, and the like of the recess), and the solder particles having a target particle size distribution (solder particles having an average particle diameter of 1 to 30 μm and a c.v. value of 20% or less) can be easily prepared.

The above method is particularly suitable for the case where the solder particles 2 are indium-based solder particles. That is, although indium solder can be deposited by plating, it is not easily deposited in the form of particles, and is a soft and difficult-to-handle material. However, in the above method, indium-based solder particles having a substantially uniform particle diameter can be easily produced by using indium-based solder particles as a raw material.

After the solder particles 2 are disposed in the recess 7, the base 6 can be operated in a state where the solder particles 2 are disposed (housed) in the recess 7. For example, when the substrate 6 is transported or stored in a state where the solder particles 2 are disposed (stored) in the recess 7, deformation of the solder particles 2 can be prevented. In addition, since the solder particles 2 are easily taken out in a state where the solder particles 2 are disposed (accommodated) in the concave portions 7, deformation such as recovery and surface treatment of the solder particles 2 is also easily prevented.

(transfer step)

In the transfer step, the 1 st adhesive layer 3 is provided on the surface (surface on which the recess 7 is formed) of the base 6, whereby the solder particles 2 are transferred to the 1 st adhesive layer 3 (see fig. 8).

Specifically, first, after the 1 st adhesive layer 3 is formed on the support 11 to obtain the laminated film 12, the surface 6a of the base 6 on which the concave portion 7 is formed (the surface of the base 6) is opposed to the 1 st adhesive layer 3 side surface (the surface of the 1 st adhesive layer 3 opposite to the support 11) of the laminated film 12, and the base 6 and the 1 st adhesive layer 3 are brought close to each other (see fig. 8 (a)). Next, the 1 st adhesive layer 3 is brought into contact with the surface (surface on which the concave portion 7 is formed) 6a of the base 6 by bonding the laminated film 12 to the base 6, whereby the solder particles 2 are transferred to the 1 st adhesive layer 3. Thus, the particle transfer layer 13 including the 1 st adhesive layer 3 and the solder particles 2 at least a part of which is embedded in the 1 st adhesive layer 3 can be obtained (see fig. 8 (b)). At this time, as shown in fig. 8 (b), when the bottom of the recess 7 is flat, the solder particles 2 have a flat portion 2a corresponding to the shape of the bottom of the recess 7, and are disposed in the 1 st adhesive layer 3 in a state where the flat portion 2a faces the opposite side to the support 11.

The 1 st adhesive layer 3 can be formed using a varnish composition (varnish-like 1 st adhesive composition) prepared by dissolving or dispersing the constituent components of the 1 st adhesive layer 3 in an organic solvent by stirring, mixing, kneading, or the like. Specifically, for example, the 1 st adhesive layer 3 can be formed by applying the varnish composition on the support 11 (for example, a substrate subjected to a mold release treatment) using an air knife coater, a roll coater, an applicator, a corner-gap wheel coater, a die coater, or the like, and then evaporating the organic solvent by heating. In this case, the thickness of the finally obtained 1 st adhesive layer can be adjusted by adjusting the coating amount of the varnish composition.

The organic solvent used in the preparation of the varnish composition is not particularly limited as long as it has a property of being able to substantially uniformly dissolve or disperse each component. Examples of such organic solvents include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, and the like. These organic solvents can be used singly or in combination of 2 or more. The stirring and mixing or kneading in the preparation of the varnish composition can be performed using, for example, a stirrer, a grinder, 3 rolls, a ball mill, a bead mill, a homogenizing and dispersing machine, or the like.

The support 11 is not particularly limited as long as it has heat resistance capable of withstanding the heating conditions at the time of volatilizing the organic solvent. The support 11 may be a plastic film or a metal foil. As the support 11, for example, a base material (e.g., film) using, as a constituent material, stretched polypropylene (OPP), polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, polyolefin, polyacetate, polycarbonate, polyphenylene sulfide, polyamide, polyimide, cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, a synthetic rubber system, a liquid crystal polymer, or the like can be used.

The heating conditions for volatilizing the organic solvent from the varnish composition applied on the substrate can be appropriately set according to the organic solvent or the like used. The heating conditions may be, for example, 40 to 120℃and 0.1 to 10 minutes.

A part of the solvent may remain in the 1 st adhesive layer 3 without being removed. The content of the solvent in the 1 st adhesive layer 3 may be, for example, 10 mass% or less based on the total mass of the 1 st adhesive layer 3.

Examples of the method for bonding the laminated film 12 to the substrate 6 include hot pressing, roll lamination, and vacuum lamination. The lamination can be performed, for example, under a temperature condition of 0 to 80 ℃.

In the transfer step, the 1 st adhesive layer 3 can be formed by directly applying the varnish composition to the substrate 6, but the particle transfer layer 13 in which the support 11, the 1 st adhesive layer 3, and the solder particles 2 are integrally formed can be easily obtained by using the laminated film 12 as described above.

(lamination step)

In the lamination step, the 2 nd adhesive layer 4 is provided on the surface of the 1 st adhesive layer 3 opposite to the support 11 (the side to which the solder particles 2 are transferred). Thus, the adhesive film 10 for circuit connection shown in fig. 1 can be obtained.

The 2 nd adhesive layer 4 may be provided on the 1 st adhesive layer 3 in the same manner as the method of providing the 1 st adhesive layer 3 on the substrate 6 except that a varnish composition (varnish-like 2 nd adhesive composition) prepared by dissolving or dispersing constituent components of the 2 nd adhesive layer 4 in an organic solvent by stirring, mixing, etc. is used instead of the varnish-like 1 st adhesive composition. That is, the 2 nd adhesive layer 4 may be provided on the 1 st adhesive layer 3 by bonding the 1 st adhesive layer 3 to a laminated film obtained by forming the 2 nd adhesive layer 4 on the support, or the 2 nd adhesive layer 4 may be provided on the 1 st adhesive layer 3 by directly applying a 2 nd adhesive composition in a varnish form to the 1 st adhesive layer 3.

In the lamination step, the 2 nd adhesive layer 4 may be provided on the surface on the side where the support 11 is provided after the support 11 is peeled off, but by providing the 2 nd adhesive layer 4 on the surface on the opposite side to the support 11 as described above, it is possible to expect improvement in the adhesion of the adhesive film for circuit connection to the circuit member and suppression of peeling at the time of connection.

The method for producing the adhesive film for circuit connection of the present invention has been described above by way of example with reference to the adhesive film for circuit connection 10 and the method for producing the same, but the present invention is not limited to the above-described embodiments.

For example, the adhesive film 1 in the adhesive film 10 for circuit connection may be composed of only the 1 st adhesive layer 3, and may further include other adhesive layers than the 1 st adhesive layer 3 and the 2 nd adhesive layer 4.

Connection structure and method for manufacturing the same

Hereinafter, a connection structure (circuit connection structure) using the above-described adhesive film 10 for circuit connection as a connection material and a method for manufacturing the same will be described.

Fig. 9 is a schematic cross-sectional view showing an embodiment of the connection structure. As shown in fig. 9, the connection structure 100 includes: a 1 st circuit part 23 having a 1 st circuit substrate 21 and a 1 st electrode 22 formed on a main surface 21a of the 1 st circuit substrate 21; a 2 nd circuit member 26 having a 2 nd circuit substrate 24 and a 2 nd electrode 25 formed on a main surface 24a of the 2 nd circuit substrate 24; and a connection portion 27 electrically connecting the 1 st electrode 22 and the 2 nd electrode 25 to each other via the solder layer 30 and bonding the 1 st circuit member 23 and the 2 nd circuit member 26.

The 1 st circuit member 23 and the 2 nd circuit member 26 may be the same as each other or may be different from each other. The 1 st circuit member 23 and the 2 nd circuit member 26 may be glass substrates or plastic substrates on which circuit electrodes are formed; a printed wiring board; a ceramic wiring board; a flexible wiring board; an IC chip such as a driving IC. The 1 st and 2 nd circuit substrates 21 and 24 may be formed of an inorganic material such as a semiconductor, glass, or ceramic, an organic material such as polyimide or polycarbonate, or a composite material such as glass/epoxy. The 1 st circuit substrate 21 may be a plastic substrate. The 1 st circuit member 23 may be, for example, a plastic substrate (a plastic substrate having an organic material such as polyimide, polycarbonate, polyethylene terephthalate, or cyclic olefin polymer as a constituent material) on which a circuit electrode is formed, and the 2 nd circuit member 26 may be, for example, an IC wafer such as a driving IC. The plastic substrate on which the electrodes are formed may be a plastic substrate on which a display region is formed by regularly arranging pixel driving circuits such as organic TFTs or a plurality of organic EL elements R, G, B in a matrix, for example.

The 1 st electrode 22 and the 2 nd electrode 25 may be electrodes containing metals such as gold, silver, tin, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, aluminum, molybdenum, titanium, or the like, oxides such as Indium Tin Oxide (ITO), indium Zinc Oxide (IZO), indium Gallium Zinc Oxide (IGZO), or the like. The 1 st electrode 22 and the 2 nd electrode 25 may be electrodes formed by stacking 2 or more of these metals, oxides, and the like. The number of electrodes formed by stacking 2 or more kinds may be 2 or more, or 3 or more. The 1 st electrode 22 and the 2 nd electrode 25 may be circuit electrodes or bump electrodes. In fig. 9, the 1 st electrode 22 is a circuit electrode, and the 2 nd electrode 25 is a bump electrode.

The total value of the height of the 1 st electrode 22 and the height of the 2 nd electrode 25 may be smaller than the average particle diameter of the solder particles 2 in the adhesive film for circuit connection used to form the connection portion 27. The total value may be, for example, 30 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, 5 μm or less, less than 4 μm, less than 3 μm, less than 2 μm or less than 1 μm. The height of the 1 st electrode 22 (e.g., the height of the circuit electrode) may be, for example, 0.05 to 5.0 μm, 0.1 to 4.0 μm, or 0.5 to 3.0 μm. The height of the 2 nd electrode 25 (e.g., the height of the bump electrode) may be, for example, 0.5 to 25.0 μm, 2.0 to 15.0 μm, or 5.0 to 10.0 μm.

The connection portion 27 is a cured product of the adhesive film 10 for circuit connection. The connection portion 27 includes, for example: a 1 st region 28 which is located on the 1 st circuit member 23 side in a direction in which the 1 st circuit member 23 and the 2 nd circuit member 26 face each other (hereinafter, referred to as a "facing direction"), and which contains a cured product of the 1 st adhesive layer 3; a 2 nd region 29 which is located on the 2 nd circuit member 26 side in the opposing direction and includes a cured product of the 2 nd adhesive layer 4; a solder layer 30 interposed between the 1 st electrode 22 and the 2 nd electrode 25 to electrically connect the 1 st electrode 22 and the 2 nd electrode 25 to each other; and solder particles 2 located between adjacent electrodes. The solder particles 2 may be in a molten state in the connection portion 27. The connection portion 27 may not have 2 distinct regions between the 1 st region 28 and the 2 nd region 29, and may include, for example, a region cured in a state where the 1 st adhesive layer 3 and the 2 nd adhesive layer 4 are mixed.

Examples of the connection structure include a color display in which a plastic substrate on which fine LED elements (light emitting elements) are regularly arranged is connected to a driving circuit element as an image display driver, and a micro LED display device such as a touch panel in which a plastic substrate on which fine LED elements are regularly arranged is connected to an input element such as a touch panel. The connection structure may be an organic EL display device in which the LED element is an organic EL element. The connection structure can also be applied to various monitors such as smart phones, tablet computers, televisions, navigation systems of vehicles, wearable terminals and the like; furniture; household appliances; daily necessities, and the like.

Fig. 10 is a schematic cross-sectional view showing an embodiment of a method for manufacturing the connection structure 100. Fig. 10 (a) and 10 (b) are schematic cross-sectional views showing the respective steps. As shown in fig. 10, the method for manufacturing the connection structure 100 includes the steps of: the adhesive film 10 for circuit connection is disposed between the surface of the 1 st circuit member 23 on which the 1 st electrode 22 is disposed and the surface of the 2 nd circuit member 26 on which the 2 nd electrode 25 is disposed; and heating the laminate including the 1 st circuit member 23, the circuit-connecting adhesive film 10, and the 2 nd circuit member 26 in a state of being pressed in a thickness direction of the laminate, thereby electrically connecting the 1 st electrode 22 and the 2 nd electrode 25 to each other via the solder layer 30 and bonding the 1 st circuit member 23 and the 2 nd circuit member 26.

Specifically, first, a 1 st circuit component 23 including the 1 st circuit board 21 and the 1 st electrode 22 formed on the main surface 21a of the 1 st circuit board 21 and a 2 nd circuit component 26 including the 2 nd circuit board 24 and the 2 nd electrode 25 formed on the main surface 24a of the 2 nd circuit board 24 are prepared.

Next, the 1 st circuit member 23 and the 2 nd circuit member 26 are arranged so that the 1 st electrode 22 and the 2 nd electrode 25 face each other, and the adhesive film 10 for circuit connection is arranged between the 1 st circuit member 23 and the 2 nd circuit member 26. For example, as shown in fig. 10 (a), the 1 st adhesive layer 3 side is opposed to the main surface 21a of the 1 st circuit board 21, and the circuit-connecting adhesive film 10 is laminated on the 1 st circuit member 23. Next, the 2 nd circuit member 26 is disposed on the 1 st circuit member 23 on which the circuit connecting adhesive film 10 is laminated so that the 1 st electrode 22 on the 1 st circuit substrate 21 and the 2 nd electrode 25 on the 2 nd circuit substrate 24 face each other.

As shown in fig. 10 (b), the laminated body formed by laminating the 1 st circuit member 23, the circuit connecting adhesive film 10, and the 2 nd circuit member 26 in this order is heated in a state of being pressed in the thickness direction of the laminated body, and the 1 st circuit member 23 and the 2 nd circuit member 26 are thermally pressed against each other. At this time, as shown by arrows in fig. 10 b, the flowable uncured thermosetting component contained in the 1 st adhesive layer 3 and the 2 nd adhesive layer 4 flows to fill the gaps of the electrodes adjacent to each other (the gaps between the 1 st electrode 22 and the gaps between the 2 nd electrode 25), and is cured by the above-mentioned heating. Then, the solder particles 2 are melted by heating in a pressed state, and are accumulated between the 1 st electrode 22 and the 2 nd electrode 25 to form the solder layer 30, and then, the solder layer 30 is fixed between the 1 st electrode 22 and the 2 nd electrode 25 by cooling. Thus, the 1 st electrode 22 and the 2 nd electrode 25 are electrically connected to each other via the solder layer 30 (melt-solidified product of the solder particles 2), and the 1 st circuit member 23 and the 2 nd circuit member 26 are bonded to each other, whereby the connection structure 100 shown in fig. 9 can be obtained.

The heating temperature at the time of connection may be, for example, 130 to 260 ℃ as long as the solder particles can be melted (for example, a temperature higher than the melting point of the solder particles). The pressurizing is not particularly limited as long as it does not damage the adherend, but for example, the area conversion pressure of the wafer may be 0.1 to 50MPa, 40MPa or less, or 0.1 to 40MPa. These heating and pressurizing times may be in the range of 0.5 to 300 seconds.

Examples

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

< preparation of Material >

In examples and comparative examples, the following materials were used as the materials of the adhesive film.

(A: cationically polymerizable Compound)

A1: CELLOXIDE8010 (bis-7-oxabicyclo [4.1.0] heptane, manufactured by Daicel Corporation)

A2: ETERNACOLL OXBP (4, 4' -bis [ 3-ethyl-3-oxetanyl ] methoxymethyl ] biphenyl manufactured by UBE INDUSTRIES, LTD.)

A3: jER1010 (bisphenol A type solid epoxy resin, manufactured by Mitsubishi Chemical Corporati on)

( B: thermal cationic polymerization initiator (thermal latent cationic initiator) )

B1: CXC-1821 (quaternary ammonium salt type thermal acid initiator, manufactured by King Industries Co., ltd.)

(C: thermoplastic resin)

C1: p-1 (fluorene type phenoxy resin synthesized by the method described later)

C2: YP-70 (bisphenol A/bisphenol F copolymerized phenoxy resin, NIPPON STEEL Chemical & Material Co., ltd.)

[ Synthesis of P-1 ]

45g of 4,4' - (9-fluorenylidene) -diphenol (manufactured by Sigma-Aldrich Japan K.K.) and 50g of 3,3', 5' -tetramethyl bisphenol diglycidyl ether (manufactured by YX-4000H,Mitsubishi Chemica l Corporation) were dissolved in 1000mL of N-methylpyrrolidone in a 3000mL three-necked flask equipped with a Dysosmate cooling tube, a calcium chloride tube, and a stirring rod made of PT FE connected to a stirring motor, to prepare a reaction solution. 21g of potassium carbonate was added thereto, and the mixture was stirred while being heated to 110℃using a heating pack. After stirring for 3 hours, the reaction was added dropwise to a beaker containing 1000mL of methanol, and the resultant precipitate was filtered by suction filtration. The collected precipitate was further washed 3 times with 300mL of methanol to obtain 75g of phenoxy resin P-1.

Thereafter, the molecular weight of the phenoxy resin P-1 was measured by using a high performance liquid chromatograph GP8020 manufactured by TOSOH CORPORATION (chromatographic column: hitachi Chemical Company, gelpak GL-A150S and GLA160S manufactured by Ltd., eluent: tetrahydrofuran, flow rate: 1.0 ml/min). As a result, mn= 15769, mw= 38045, and Mw/mn=2.413 were calculated as polystyrene transforms.

(D: filler)

D1: AEROSIL R805 (hydrolysis product of trimethoxyoctylsilane and silica (silica particles), manufactured by Evonik Industries AG, using a solvent diluted to 10% by mass of nonvolatile matter)

D2: surface-treated silica particles (hydrolysis product of silica and bis (trimethylsilyl) amine)

(E: coupling agent)

E1: KBM-403 (gamma-glycidoxypropyl trimethoxysilane, shin-Etsu Chemical Co., ltd.)

Preparation of the substrate

A substrate (A) (PET film, thickness: 55 μm), a substrate (B) (PET film, thickness: 54 μm) and a substrate (C) (PET film, thickness: 57 μm) having a plurality of recesses on the surface thereof were prepared.

The concave portion of the base (A) was formed in a conical trapezoid shape having an opening area enlarged toward the front surface side of the base (the center of the bottom portion is the same as the center of the opening portion when viewed from the top surface of the opening portion), the opening diameter was set to 4.3 μm phi, the bottom portion diameter was set to 4.0 μm phi, and the depth was set to 4.0 μm. The plurality of recesses of the base (a) were regularly formed in a three-way arrangement at intervals of 6.2 μm (center-to-center distances of the respective bottoms) so that 29,000 recesses were formed every 1mm square.

The concave portion of the base (B) was formed in a conical trapezoid shape having an opening area enlarged toward the front surface side of the base (the center of the bottom portion is the same as the center of the opening portion when viewed from the top surface of the opening portion), the opening diameter was set to 3.3 μm phi, the bottom portion diameter was set to 3.0 μm phi, and the depth was set to 3.0 μm. Further, a plurality of concave portions were regularly formed at intervals of 6.2 μm (center-to-center distances of the respective bottoms) in a three-way arrangement so that 29,000 were formed every 1mm square.

The concave portion of the base (C) was formed in a conical trapezoid shape having an opening area enlarged toward the front surface side of the base (the center of the bottom portion is the same as the center of the opening portion when viewed from the top surface of the opening portion), the opening diameter was set to 5.3 μm phi, the bottom portion diameter was set to 5.0 μm phi, and the depth was set to 5.0 μm. Further, a plurality of concave portions were regularly formed at intervals of 6.2 μm (center-to-center distances of the respective bottoms) in a three-way arrangement so that 29,000 were formed every 1mm square.

Example 1 to example 8, comparative example 1 to comparative example 6 >

Examples 1 to 8 and comparative examples 1 to 6 each having an adhesive film having the composition shown in table 1 and conductive particles disposed in the adhesive film were prepared by the following method. As the step (a), the step (a 1) was performed in examples 1 to 5, comparative examples 1 to 3 and comparative example 5, the step (a 2) was performed in example 6, the step (a 3) was performed in example 7 and comparative example 4, the step (a 4) was performed in example 8, and the step (a 5) was performed in comparative example 6.

(step (a)) preparation step

[ step (a 1): production and arrangement of solder particles (type: F1, average particle size: 4.0 μm)

100g of Sn-Bi solder particles (manufactured by 5N Plus Inc. having a melting point of 138 ℃ C., type 8) were immersed in distilled water, and after ultrasonic dispersion, leveling was performed, whereby solder particles floating in the supernatant liquid were recovered. This operation was repeated, and 10g of solder particles were recovered. The obtained solder particles had an average particle diameter of 1.0 μm and a c.v. value of 42%. Next, the obtained solder particles (average particle diameter: 1.0 μm, C.V. value of particle diameter: 42%) were disposed on the surface of the base (A) on which the recesses were formed. Then, the surface of the substrate (a) on which the concave portions are formed is scraped with a micro-adhesive roller to remove excessive solder particles, and only the solder particles are disposed in the concave portions. Next, the substrate having the solder particles disposed in the concave portions was put into a hydrogen radical reduction furnace (SHINKO SEIKI co., ltd. Manufactured by ltd.) and then, after vacuum-pumping, hydrogen gas was introduced into the furnace to fill the furnace with hydrogen gas. Thereafter, the temperature in the furnace was adjusted to 120℃and the hydrogen radicals were irradiated for 5 minutes. Thereafter, the hydrogen gas in the furnace was removed by vacuum evacuation, and after heating to 145 ℃, the nitrogen gas was introduced into the furnace to return to atmospheric pressure, and then the temperature in the furnace was lowered to room temperature, whereby solder particles were formed. Thus, a substrate having conductive particles (solder particles) disposed in the recesses is prepared for use in the step (b 2).

In addition, solder particles were produced by the same operation, and the obtained solder particles were recovered from the concave portion by striking the back side of the concave portion of the base. It was confirmed that a part of the surface of the solder particle had a flat surface portion, and the ratio (B/a) of the diameter B of the flat surface portion to the diameter a of the solder particle was 0.35. When a quadrangle circumscribed with the projected image of the solder particles was formed from two pairs of parallel lines, it was confirmed that when the distance between the opposing sides was X and Y (where Y < X), Y/X was 0.93. When the average particle diameter and the c.v. value of the particle diameter of the solder particles were measured, the average particle diameter was 4.0 μm, and the c.v. value of the particle diameter was 7.9%. The average particle diameter of the solder particles and the average particle diameter of B/A, Y/X were measured by cutting the particle transfer layer produced in the step (B) into 10cm×10cm, performing Pt sputtering on the surface on which the solder particles are disposed, and then performing SEM observation on 300 solder particles.

[ step (a 2): production and arrangement of solder particles (type: F1, average particle size: 3.0 μm)

A substrate (B) was used instead of the substrate (a), and a substrate having conductive particles (solder particles) disposed in recesses, which was used in the step (B2), was prepared in the same manner as in the step (a 1).

In addition, solder particles were produced by the same operation, and the obtained solder particles were recovered from the concave portion by striking the back side of the concave portion of the base. It was confirmed that a part of the surface of the solder particle had a flat surface portion, and the ratio (B/a) of the diameter B of the flat surface portion to the diameter a of the solder particle was 0.40. When a quadrangle circumscribed with the projected image of the solder particles was formed from two pairs of parallel lines, it was confirmed that when the distance between the opposing sides was X and Y (where Y < X), Y/X was 0.93. When the average particle diameter and the c.v. value of the particle diameter of the solder particles were measured, the average particle diameter was 3.0 μm, and the c.v. value of the particle diameter was 8.8%. The average particle diameter of the solder particles and the average particle diameter of B/A, Y/X were measured by cutting the particle transfer layer produced in the step (B) into 10cm×10cm, performing Pt sputtering on the surface on which the solder particles are disposed, and then performing SEM observation on 300 solder particles.

[ step (a 3): production and arrangement of solder particles (type: F1, average particle size: 5.0 μm)

A substrate (C) was used instead of the substrate (a), and a substrate having conductive particles (solder particles) disposed in recesses, which was used in the step (b 2), was prepared in the same manner as in the step (a 1).

In addition, solder particles were produced by the same operation, and the obtained solder particles were recovered from the concave portion by striking the back side of the concave portion of the base. It was confirmed that a part of the surface of the solder particle had a flat surface portion, and the ratio (B/a) of the diameter B of the flat surface portion to the diameter a of the solder particle was 0.44. When a quadrangle circumscribed with the projected image of the solder particles was formed from two pairs of parallel lines, it was confirmed that when the distance between the opposing sides was X and Y (where Y < X), Y/X was 0.93. When the average particle diameter and the c.v. value of the particle diameter of the solder particles were measured, the average particle diameter was 5.0 μm, and the c.v. value of the particle diameter was 7.6%. The average particle diameter of the solder particles and the average particle diameter of B/A, Y/X were measured by cutting the particle transfer layer produced in the step (B) into 10cm×10cm, performing Pt sputtering on the surface on which the solder particles are disposed, and then performing SEM observation on 300 solder particles.

[ step (a 4): production and arrangement of solder particles (type: F2, average particle size: 4.0 μm)

Solder particles were formed in the same manner as in step (a 1) except that Sn-Ag-Cu solder particles (manufactured by MITSUI MINING & SMELTING CO. LTD., melting point was 219 ℃, ST-3) were used instead of Sn-Bi solder particles, the temperature before the irradiation of hydrogen radicals in the hydrogen radical reduction furnace was 200 ℃ instead of 120 ℃, and the heating temperature after the removal of hydrogen gas in the furnace was 225 ℃ instead of 145 ℃, and a base body having conductive particles (solder particles) disposed in recesses and used in step (b 2) was prepared.

In addition, solder particles were produced by the same operation, and the obtained solder particles were recovered from the concave portion by striking the back side of the concave portion of the base. It was confirmed that a part of the surface of the solder particle had a flat surface portion, and the ratio (B/a) of the diameter B of the flat surface portion to the diameter a of the solder particle was 0.35. When a quadrangle circumscribed with the projected image of the solder particles was formed from two pairs of parallel lines, it was confirmed that when the distance between the opposing sides was X and Y (where Y < X), Y/X was 0.93. When the average particle diameter and the c.v. value of the particle diameter of the solder particles were measured, the average particle diameter was 4.0 μm, and the c.v. value of the particle diameter was 7.9%. The average particle diameter of the solder particles and the average particle diameter of B/A, Y/X were measured by cutting the particle transfer layer produced in the step (B) into 10cm×10cm, performing Pt sputtering on the surface on which the solder particles are disposed, and then performing SEM observation on 300 solder particles.

[ step (a 5): preparation and arrangement of conductive particles (type: F3, average particle size: 3.9 μm)

As the conductive particles, conductive particles (type: F3, average particle diameter: 3.9 μm, C.V. value of particle diameter: 3.0%, specific gravity: 2.7) in which a nickel layer having a thickness of 0.15 μm was formed on the surface of a core (particle) composed of a plastic (crosslinked polystyrene) were prepared, and the particles were arranged on the surface of the substrate (A) on which the concave portion was formed. Next, the surface of the substrate (a) on which the concave portions are formed is scraped with a micro adhesive roller to remove excess conductive particles, and only the conductive particles are disposed in the concave portions. The average particle diameter and c.v. value of the particle diameter of the conductive particles were measured by cutting the particle transfer layer produced in the step (b) into 10cm×10cm, performing Pt sputtering on the surface on which the conductive particles were disposed, and then subjecting 300 conductive particles to SEM observation.

(step (b)) transfer step

[ step (b 1): production of the 1 st adhesive layer ]

The components shown as X1 or X2 in Table 1 were mixed together with an organic solvent (2-butanone) in the blending amounts shown in Table 1 (unit: parts by mass, amount of solid components), to obtain resin solutions. Next, the resin solution was applied to a PET film having a thickness of 38 μm subjected to silicone release treatment, and hot air drying was performed at 60 ℃ for 3 minutes, thereby producing a 1 st adhesive layer having the thickness shown in tables 2 to 4 on the PET film.

[ step (b 2): transfer of conductive particles

The 1 st adhesive layer formed on the PET film produced in the step (b 1) is disposed so as to face the substrate having the conductive particles disposed in the recesses produced in the step (a), and the conductive particles are transferred to the 1 st adhesive layer. Thus, a particle transfer layer was obtained.

(step c: lamination step)

[ step (c 1): production of the 2 nd adhesive layer

The components shown as X1 or X2 in Table 1 were mixed together with an organic solvent (2-butanone) in the blending amounts shown in Table 1 (unit: parts by mass, amount of solid components), to obtain resin solutions. Next, the resin solution was applied to a PET film having a thickness of 50 μm subjected to silicone release treatment, and hot air drying was performed at 60 ℃ for 3 minutes, thereby producing a 2 nd adhesive layer having the thickness shown in tables 2 to 4 on the PET film.

[ step (c 2): lamination of the 2 nd adhesive layer

The particle transfer layer produced in step (b) and the 2 nd adhesive layer produced in step (c 1) are bonded together while applying a temperature of 50 ℃. Thus, an anisotropically conductive adhesive film was obtained. The ratio r of the thickness of the anisotropic conductive adhesive film to the average particle diameter of the conductive particles is shown in tables 2 to 4.

(measurement of distance from adhesive film surface to conductive particle)

After the anisotropic conductive adhesive film was injection molded using an epoxy resin injection molding resin (manufactured by finer Tec ltd., trade name: epomo unt), a cross section of the conductive adhesive film was cut out. Thereafter, a section was observed using a metal FPD/LSI inspection microscope L300ND manufactured by Nikon Solutions co., ltd. And the shortest distance from the 1 st adhesive layer side surface of the anisotropic conductive adhesive film to the surface of the conductive particles and the shortest distance from the 2 ND adhesive layer side surface of the anisotropic conductive adhesive film to the surface of the conductive particles were measured at 10, and the average of the measured values at 10 was taken as shortest distance d11 and shortest distance d21, respectively. The results are shown in tables 2 to 4.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

< evaluation >

(measurement of curing Rate of Anisotropic conductive adhesive film)

Anisotropic conductive adhesive films of examples 1 to 8 and comparative examples 1 to 6 were prepared by using a differential scanning calorimeter (trade name: DSC Q1000) manufactured by Perkinelmer, inc. under the condition of nitrogen (N ₂ ) DSC measurement was performed at a temperature rise rate of 10 ℃/min under an atmosphere to determine the heat generation amount Q when heating from 50 ℃ to 130 DEG C _A Heating value Q when heating from 50 ℃ to 160 DEG C _B Heating value Q when heating from 50 ℃ to 210 DEG C _C And a heat generation amount Q when heated from 50 ℃ to 300 DEG C _D . In any anisotropic conductive adhesive film, no increase in heat generation was observed at a temperature of 300℃or higher (the change rate of the differential curve (DDSC curve) of DSC curve was 0.01[ W.g. ] C]Hereinafter), it was judged that the cured product was completely cured at 300 ℃. Based on the obtained heat generation amount Q _A 、Q _B 、Q _C Q and Q _D Respectively find 130Cure Rate A (Q) at DEG C _A /Q _D X 100), cure rate B (Q) at 160 DEG C _B /Q _D X 100), cure C (Q) at 210 ℃ _C /Q _D X 100). The results are shown in tables 5 and 6.

(measurement of monodisperse Rate of conductive particles in Anisotropic conductive adhesive film)

The anisotropic conductive adhesive films of examples 1 to 8 and comparative examples 1 to 6 were observed from the 1 st adhesive layer side at a magnification of 200 times using a metal microscope, the number of conductive particles in the anisotropic conductive adhesive film was actually measured, and the monodispersity of the conductive particles was determined according to the following formula. The monodispersity of the conductive particles in the anisotropic conductive adhesive films of examples 1 to 8 and comparative examples 1 to 6 was 98%.

Monodisperse (%) = (2500 μm) ² Conductive particle count in monodisperse state/2500 μm ² Number of conductive particles) x 100

(evaluation of connection resistance and insulation resistance)

[ preparation of Circuit Components ]

As the 1 st circuit component, a substrate (A) with electrodes, in which Cr (20 nm)/Au (200 nm) electrodes (electrode size: 22 μm. Times.22 μm, electrode space: 8 μm) were formed on the surface of an alkali-free glass substrate (manufactured by OA-11,Nippon Electric Glass Co, ltd., outline: 76 mm. Times.28 mm, thickness: 0.3 mm) was prepared. As the 2 nd circuit member, a sapphire wafer (outer shape: 0.5 mm. Times.0.5 mm, thickness: 0.2mm, size of bump electrode: 20. Mu.m. Times.20. Mu.m, inter-bump space: 10. Mu.m, bump electrode thickness: 1.5 μm) was prepared with bump electrodes arranged.

[ production of connection Structure (A) ]

The anisotropic conductive adhesive films of examples 1 to 8 and comparative examples 1 to 6 were used to produce a connection structure (a). Specifically, first, an anisotropic conductive adhesive film is disposed on the 1 st circuit member. Next, a thermocompression bonding device (LD-06,OHASHI ENGINEERING Co, ltd) composed of a stage including a ceramic heater and a tool (8 mm×50 mm) was used.Manufactured) at 50℃and 0.98MPa (10 kgf/cm) ² ) The anisotropic conductive adhesive film was bonded to the 1 st circuit member under heating and pressure for 2 seconds, and the release film (PET film) on the opposite side of the anisotropic conductive adhesive film to the 1 st circuit member side was peeled off. Next, after the bump electrodes of the 1 st circuit member and the circuit electrodes of the 2 nd circuit member were aligned, heating/pressurizing was started on the mount heated to 30 ℃ under the conditions of a temperature of 50 ℃ and a pressure of 1MPa, and the pressure was kept substantially constant (1 MPa) and was raised to 160 ℃ or 230 ℃ under the conditions of 1 ℃/sec, whereby the anisotropic conductive adhesive film was bonded to the 2 nd circuit member, and a connection structure (a) was produced. The temperature represents the highest measured temperature of the anisotropic conductive adhesive film, and the pressure represents the value calculated for the wafer area of the 2 nd circuit member. The temperature of the temperature rise was 160℃in examples 1 to 7 and comparative examples 1 to 6, and 230℃in example 8.

[ evaluation of connection resistance ]

The measurement was performed by a four-point measurement method, and the connection resistance was evaluated by using the average value of the connection resistance values measured at 4 immediately after the production of the connection structure (a) and after the 250-hour treatment in a high-temperature and high-humidity tank having a temperature of 85 ℃ and a humidity of 85% rh. As the current generating device, 6240B (trade name) manufactured by ADC CORPORATION was used, and as the digital multimeter, 7461A (trade name) manufactured by ADC CORPORATION was used. The connection resistance is less than 0.2Ω as "S" determination, the connection resistance is 0.2Ω or more and less than 0.5Ω as "a" determination, and the connection resistance is 0.5Ω or more as "D" determination. The results are shown in tables 5 and 6.

[ evaluation of insulation resistance ]

Immediately after the production of the connection structure (a) and after 250 hours of treatment in a high-temperature and high-humidity tank having a temperature of 85 ℃ and a humidity of 85% rh, the insulation resistance was evaluated using the minimum value of the insulation resistance measured at 4. The insulation resistance meter used SM7120 (trade name)). The insulation resistance value is 1.0X10 ¹⁰ The case of Ω or more was evaluated as "S" determination, and the insulation resistance value was 1.0x10 ⁹ Omega or more and less than 1.0X10 ¹⁰ The case of Ω was evaluated as "a" judgment, and the insulation resistance value was less than 1.0X10 ⁹ The case of Ω is evaluated as "D" judgment. The results are shown in tables 5 and 6.

(evaluation of particle capturing Rate)

[ production of connection Structure (B) ]

The anisotropic conductive adhesive films of examples 1 to 8 and comparative examples 1 to 6 were used to produce a connection structure (B). The connection structure (B) was produced in the same manner as the production of the connection structure (A) except that an electrode-carrying substrate (B) having an ITO (220 nm) electrode (electrode size: 22 μm. Times.22 μm, electrode space: 8 μm) was formed on the surface of an alkali-free glass substrate (OA-11,Nippon Electric Glass Co, ltd.) as the 1 st circuit component, and the electrode-carrying substrate (B) was used instead of the electrode-carrying substrate (A).

[ evaluation of particle capturing Rate ]

The connection site of the connection structure (B) was observed from the substrate (B) side with a voltage using a metal FPD/LSI inspection microscope L300ND manufactured by Nikon Solutions co. Using the obtained average captured particle number and the density of conductive particles in the anisotropic conductive adhesive film (29000 pieces/mm ² ) And the capturing ratio of the conductive particles captured between the electrodes is calculated according to the following formula. The method comprises the steps of evaluating a case in which the capturing rate of the conductive particles is 70% or more as an "S" judgment, evaluating a case in which the capturing rate of the conductive particles is 60% or more and less than 70% as an "A" judgment, evaluating a case in which the capturing rate of the conductive particles is 50% or more and less than 60% as a "B" judgment, and obtaining a case in which the capturing rate of the conductive particles is less than 50% of the cases were evaluated as "D" decisions. The results are shown in tables 5 and 6.

The capturing ratio (%) of the conductive particles= (average capturing particle number/(bump electrode area×density of conductive particles in the anisotropic conductive adhesive film)) ×100[ table 5]

TABLE 6

Symbol description

1-adhesive film, 2-solder particles, 3-1 st adhesive layer, 4-2 nd adhesive layer, 6-base, 7-recess, 10-adhesive film for circuit connection, 21-1 st circuit substrate, 22-1 st electrode (circuit electrode), 23-1 st circuit member, 24-2 nd circuit substrate, 25-2 nd electrode (bump electrode), 26-2 nd circuit member, 27-connection portion, 30-solder layer, 100-connection structure.

Claims (10)

1. An adhesive film for circuit connection, which is a thermosetting adhesive film for circuit connection,

Which contains solder particles having an average particle diameter of 1 to 30 mu m and a C.V. value of 20% or less,

the ratio of the thickness of the adhesive film for circuit connection to the average particle diameter of the solder particles exceeds 1.0 and is less than 1.5,

if the melting point of the solder particles is set to T _m T when heating at a heating rate of 10 ℃/min under a nitrogen atmosphere _m The curing rate at the temperature is more than 80 percent.

2. The adhesive film for circuit connection according to claim 1, which contains a polymerizable compound and a thermal polymerization initiator.

3. The adhesive film for circuit connection according to claim 2, wherein,

the polymerizable compound is a cationically polymerizable compound, and the thermal polymerization initiator is a thermal cationic polymerization initiator.

4. The adhesive film for circuit connection according to claim 3, wherein,

the polymerizable compound includes at least one selected from the group consisting of alicyclic epoxy compounds and oxetane compounds.

5. The adhesive film for circuit connection according to any one of claims 1 to 4, wherein,

the melting point of the solder particles is 280 ℃ or lower.

6. The adhesive film for circuit connection according to any one of claims 1 to 5 for bonding a 1 st circuit part having a 1 st electrode to a 2 nd circuit part having a 2 nd electrode and electrically connecting the 1 st electrode and the 2 nd electrode to each other,

The total of the height of the 1 st electrode and the height of the 2 nd electrode is smaller than the average particle diameter of the solder particles.

7. A connection structure is provided with: a 1 st circuit part having a 1 st electrode; a 2 nd circuit part having a 2 nd electrode electrically connected to the 1 st electrode; and a connection portion electrically connecting the 1 st electrode and the 2 nd electrode to each other via a solder layer and bonding the 1 st circuit component and the 2 nd circuit component,

the connecting portion comprises a cured product of the adhesive film for circuit connection according to any one of claims 1 to 6.

8. The connection structure according to claim 7, wherein,

the total of the height of the 1 st electrode and the height of the 2 nd electrode is smaller than the average particle diameter of the solder particles.

9. A method of manufacturing a connection structure, comprising the steps of:

disposing the adhesive film for circuit connection according to any one of claims 1 to 6 between a surface of a 1 st circuit member having a 1 st electrode provided with the 1 st electrode and a surface of a 2 nd circuit member having a 2 nd electrode provided with the 2 nd electrode; a kind of electronic device with high-pressure air-conditioning system

And heating a laminate including the 1 st circuit member, the adhesive film for circuit connection, and the 2 nd circuit member in a state of being pressed in a thickness direction of the laminate, thereby electrically connecting the 1 st electrode and the 2 nd electrode to each other via a solder layer and bonding the 1 st circuit member and the 2 nd circuit member.

10. The method for manufacturing a connection structure according to claim 9, wherein,

the total of the height of the 1 st electrode and the height of the 2 nd electrode is smaller than the average particle diameter of the solder particles.