JP6155651B2 - Conductive particles, insulating coated conductive particles, and anisotropic conductive adhesive - Google Patents

Description

  The present invention relates to conductive particles, insulating coated conductive particles, anisotropic conductive adhesive, a circuit member connection structure, and a method for manufacturing the same.

  The method of mounting a liquid crystal driving IC on a liquid crystal display glass panel can be broadly divided into COG (Chip-on-Glass) mounting and COF (Chip-on-Flex) mounting. In COG mounting, an IC for liquid crystal is directly bonded onto a glass panel using an anisotropic conductive adhesive. On the other hand, in COF mounting, a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and these are bonded to a glass panel using an anisotropic conductive adhesive. Anisotropy here means conducting in the pressurizing direction and maintaining insulation in the non-pressurizing direction.

  Conventionally, as an anisotropic conductive adhesive, an adhesive containing conductive particles having a gold layer formed on the surface has been mainly used. Such conductive particles have a low electrical resistance value. Further, since gold is not likely to be oxidized, the electrical resistance value does not increase even when stored for a long period of time. However, attempts have been made to reduce the amount of current flowing through an integrated circuit in order to reduce power consumption in response to recent energy savings. Accordingly, there has been a demand for conductive particles having a lower electrical resistance than before.

  Patent Documents 1 to 3 disclose conductive particles in which copper plating is formed on the surface of plastic particles. Since copper is a metal having an electric resistance smaller than that of gold, according to copper plating, conductive particles having an electric resistance lower than that of gold-plated conductive particles can be obtained. However, it is known that in the process of producing conductive particles in which copper plating is formed on the surface of plastic particles, the particles are likely to aggregate during electroless copper plating.

  In order to improve this cohesiveness, Patent Document 4 describes a method of forming an alloy plating film containing nickel, copper and phosphorus on a resin surface by an electroless plating method. Specifically, an electroless nickel plating containing phosphorus by an initial electroless plating reaction by adding a plating solution containing a nickel salt, a phosphorus reducing agent and a pH adjuster to a suspension containing core material particles. Form a film. Thereafter, a late alloy plating film containing nickel, copper and phosphorus is formed by a late electroless plating reaction performed by adding a plating solution containing a nickel salt, a copper salt, a phosphorus-based reducing agent and a pH adjuster.

Japanese Patent No. 3581618 JP 2009-48991 A Japanese Patent No. 4352097 JP 2006-52460 A

  In the method described in Patent Document 4, since the latter alloy plating film contains copper, the electric resistance is smaller than that of an alloy plating film made of nickel and phosphorus. However, since the initial alloy plating film is an alloy plating film made of nickel and phosphorus, the ductility is remarkably lower than that of copper. In addition, the late alloy plating film contains phosphorus, so that the ductility is low as compared with copper. It has been found that the electrical resistance value increases when the conductive particles having the structure of the plating film are compressed. Specifically, when the conductive particles are sandwiched between an upper surface and a lower surface parallel to the upper surface and compressed until the size becomes 20% of the original particle size (compression rate 80%), the resin particles The present inventors have found that peeling easily occurs between the plating films, and the electrical resistance value increases. Further, when particles are aggregated during the formation of the plating film, pinholes are generated in the metal layer of the conductive particles. When conductive particles having pinholes are compressed, cracking of the plating film tends to occur starting from the pinhole formation portion, which is considered to cause an increase in electrical resistance.

  Accordingly, an object of the present invention is to provide conductive particles that can maintain a low electric resistance value even when compressed and have few pinholes. Moreover, it aims at providing the insulation coating electrically-conductive particle and anisotropic conductive adhesive using this.

  In order to solve the above problems, the present invention comprises resin particles and a metal layer provided on the surface of the resin particles, the metal layer containing nickel and copper, and away from the surface of the resin particles. Therefore, a conductive particle having a portion where the element ratio of copper to nickel is high is provided. By having such a portion in the metal layer, the conductive particles can maintain a low electric resistance value even when compressed, and there are few pinholes.

  The metal layer has at least a Ni—Cu layer mainly composed of nickel and copper, and this Ni—Cu layer is the above portion (a portion where the element ratio of copper to nickel increases as the distance from the surface of the resin particle increases). You may have. Here, the Ni—Cu layer is a first layer (first part) containing 97 wt% or more of nickel in the order close to the resin particles, a second layer (second part) forming the above part, And it is preferable to have the structure where the 3rd layer (3rd part) which has copper as a main component is arrange | positioned. According to this, the said effect is further show | played.

  The total of the nickel content and the copper content in the second layer is preferably 97% by weight or more. Moreover, it is preferable that the copper content rate in a 3rd layer is 97 weight% or more. According to these, when conductive particles are highly compressed and crimped and connected, cracking of the metal after compression can be further suppressed.

  The first layer, the second layer, and the third layer are preferably formed by an electroless plating solution containing nickel, copper, and formaldehyde. In particular, it is preferable that the first layer and the second layer are sequentially formed in an electroless plating solution in one building tub. By sequentially forming a plurality of layers in one building tub, it is possible to maintain good adhesion between the first layer, the second layer, and the third layer.

  The metal layer may further include a fourth layer containing nickel and not containing copper outside the Ni—Cu layer. The metal layer may further include a fifth layer containing palladium outside the Ni—Cu layer. These layers function as a copper migration stop layer.

  The nickel content in the fourth layer is preferably 85 to 99% by weight. When the content ratio of nickel in the fourth layer is within this range, the depositability of the nickel plating film on the third layer is improved, and it is possible to suppress the formation of a place where the nickel layer is not partially deposited.

  The metal layer may further include a sixth layer containing gold outside the Ni—Cu layer. According to this layer, the electrical resistance value on the surface of the conductive particles is lowered, and the characteristics can be improved. It can also be expected as a copper migration stop layer.

  The conductive particles of the present invention preferably have an average particle size of 1 to 10 μm, and more preferably 2 to 5 μm.

  The present invention also provides insulating coated conductive particles comprising the above conductive particles and insulator particles provided on the surface of the metal layer of the conductive particles and covering at least a part of the surface.

  The present invention also provides an anisotropic conductive adhesive comprising the conductive particles or the insulating coated conductive particles in an adhesive.

  Furthermore, this invention provides the connection structure of a circuit member, and its manufacturing method. The circuit member connection structure according to the present invention includes a first circuit member in which a plurality of first circuit electrodes are formed on the main surface of the first circuit board, and a main surface of the second circuit board. A second circuit member having a plurality of second circuit electrodes formed thereon, and a first circuit board and a second circuit board provided between a main surface of the first circuit board and a main surface of the second circuit board. A circuit connection member for connecting the first and second circuit members with the electrodes facing each other, the circuit connection member being made of a cured product of the anisotropic conductive adhesive, and the first circuit The electrode and the second circuit electrode are electrically connected via the conductive particles or the insulating coated conductive particles. A method for manufacturing a circuit member connection structure according to the present invention includes: a first circuit member having a plurality of first circuit electrodes formed on a main surface of a first circuit board; and a second circuit board. The anisotropic conductive adhesive in the state where the first circuit electrode and the second circuit electrode are opposed to each other between the second circuit member having a plurality of second circuit electrodes formed on the main surface. A step of interposing an agent, and a step of curing the anisotropic conductive adhesive by heating and pressing.

  ADVANTAGE OF THE INVENTION According to this invention, even when it compresses, a low electrical resistance value can be maintained, and the conductive particle with few pinholes and the insulation coating conductive particle using the same are provided. Moreover, according to this invention, the anisotropic conductive adhesive containing the said electroconductive particle or insulation coating electroconductive particle is provided. Furthermore, according to this invention, the method of manufacturing a connection structure using the said anisotropic conductive adhesive, and the connection structure manufactured by this are provided.

(A) is sectional drawing which shows typically one Embodiment of the electroconductive particle which concerns on this invention, (b) is a graph which shows an example of the content rate of nickel and copper of a metal layer. (A)-(c) is sectional drawing which shows typically other embodiment of the electroconductive particle which concerns on this invention. It is sectional drawing which shows typically an example of the connection structure in which circuit electrodes were connected. It is sectional drawing which shows typically an example of the manufacturing method of a connection structure. It is the result of having analyzed the cross section of the plating film of the electroconductive particle produced in Example 1 by EDX.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

<Conductive particles>
A conductive particle 2 shown in FIG. 1A includes a resin particle 2a constituting a core of the conductive particle 2 and a metal layer 3 provided on the surface of the resin particle 2a. The metal layer 3 contains nickel and copper, and has a portion where the element ratio of copper to nickel increases as the distance from the surface of the resin particle 2a increases. This portion may be a part of the metal layer 3 in the thickness direction and a layer provided so as to cover almost the entire resin particle 2a or the entire. In other words, the metal layer 3 has at least a layer containing nickel and copper as main components (hereinafter also referred to as “Ni—Cu layer”) 3 a as the above portion, and the Ni—Cu layer 3 a is an element of copper with respect to nickel. You may have the density | concentration gradient from which the ratio becomes high in the direction away from the surface of the resin particle.

  The total of the nickel content and the copper content in the Ni-Cu layer 3a is preferably 97% by weight or more, more preferably 98.5% by weight or more, and 99.5% by weight or more. More preferably. The upper limit of the sum of the nickel content and the copper content in the Ni-Cu layer 3a is 100% by weight. In addition, the element ratio of copper to nickel in the Ni—Cu layer 3a has a concentration gradient that increases in a direction away from the surface of the resin particle 2a, and this concentration gradient is preferably continuous. The element ratio in the present invention is, for example, an EDX (energy dispersive X-ray spectroscope) attached to a transmission electron microscope by cutting out a cross section of a conductive particle with a focused ion beam and observing it with a transmission electron microscope of 400,000 times. The element ratio in the metal layer (for example, a first layer, a second layer, and a third layer described later) can be measured by component analysis using JEOL Datum Co., Ltd.

  The average particle diameter of the conductive particles 2 is preferably in the range of 1 to 10 μm, and more preferably in the range of 2 to 5 μm. By making the average particle diameter of the conductive particles 2 in the range of 1 to 10 μm, it becomes difficult to be affected by variations in the height of the electrodes when a connection structure is produced using an anisotropic conductive adhesive. The average particle diameter of the conductive particles 2 is obtained by observing and measuring 300 arbitrary conductive particles with an electron microscope and taking the average value thereof.

[Resin particles]
The material of the resin particles 2a is not particularly limited, and examples thereof include acrylic resins such as polymethyl methacrylate and polymethyl acrylate, and polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polybutadiene. Moreover, as the resin particles 2a, for example, crosslinked acrylic particles, crosslinked polystyrene particles, and the like can be used.

[Metal layer]
The metal layer 3 has at least a Ni—Cu layer 3a. Ni-Cu layer 3a is composed of, in order close to the resin particles 2a, second containing a first layer (first portion) 3a ₁ containing 97 wt% or more of nickel, an alloy mainly containing nickel and copper 2 layer (second portion) 3a ₂ and a third layer (third portion) 3a ₃ mainly composed of copper are preferably stacked (see FIG. 1B). .

(First layer, second layer, third layer)
The first layer 3a ₁ contains 97% by weight or more of nickel. The nickel content of the first layer 3a ₁ is more preferably 98.5% by weight or more, and further preferably 99.5% by weight or more. When nickel is 97% by weight or more, cracking of the metal after compression can be further suppressed when the conductive particles 2 are subjected to high pressure compression bonding. The upper limit of the nickel content is 100% by weight.

The thickness of the first layer 3a ₁ is preferably in the range of 20 to 200 mm (2 to 20 nm), more preferably in the range of 20 to 150 mm (2 to 15 nm), and still more preferably in the range of 60 to 100 mm (6 to 10 nm). . If the thickness of the first layer is less than 20 mm (2 nm), the metal tends to aggregate during plating. If the thickness exceeds 200 mm (20 nm), when the conductive particles are highly compressed and connected by pressure bonding, a metal is formed at the nickel portion. There is a tendency that cracks are likely to occur.

The second layer 3a ₂ contains an alloy mainly composed of nickel and copper. The total of the nickel content and the copper content in the second layer 3a ₂ is preferably 97% by weight or more, more preferably 98.5% by weight or more, and 99.5% by weight. More preferably, it is the above. When the content is 97% by weight or more, cracking of the metal after compression can be further suppressed when the conductive particles 2 are subjected to high pressure compression connection. The upper limit of the total content of nickel and copper is 100% by weight.

The thickness of the second layer 3a ₂ is preferably in the range of 20 to 500 mm (2 to 50 nm), more preferably in the range of 20 to 400 mm (2 to 40 nm), and still more preferably in the range of 20 to 200 mm (2 to 20 nm). . If the thickness of the second layer 3a ₂ is less than 20 mm (2 nm), it tends to agglomerate during plating. If the thickness exceeds 500 mm (50 nm), when the conductive particles 2 are subjected to high pressure compression bonding, There is a tendency that metal cracking is likely to occur at the portion.

The third layer 3a ₃ is mainly composed of copper. The content of copper in the _third layer 3a ₃ is preferably 97% by weight or more, preferably 98.5% by weight or more, and more preferably 99.5% by weight or more. When the content is 97% by weight or more, cracking of the metal after compression can be further suppressed when the conductive particles 2 are subjected to high pressure compression connection. The upper limit of the copper content is 100% by weight.

The thickness of the third layer 3a ₃ is preferably in the range of 100 to 2000 mm (10 to 200 nm), more preferably in the range of 200 to 1500 mm (20 to 150 nm), and still more preferably in the range of 300 to 1000 mm (30 to 100 nm). . If the thickness of the third layer 3a ₃ is less than 100 mm (10 nm), the conductivity tends to decrease, and if it exceeds 2000 mm (200 nm), the conductive particles tend to aggregate during plating.

The metal layer 3 of the conductive particle 2 shown in FIG. 1A is composed of a Ni—Cu layer 3a. FIG.1 (b) is a graph which shows the nickel content rate and copper content rate of the thickness direction of the metal layer 3 (Ni-Cu layer 3a). In the graph, the boundary line between the first layer 3a ₁ and the second layer 3a ₂ is drawn so as to pass through the point where the Ni content (solid line) has decreased to 97% by weight. On the other hand, the boundary line between the second layer 3a ₂ and the third layer 3a ₃ is drawn so as to pass through a point where the Cu content (broken line) has increased to 97% by weight.

The first layer 3a ₁ , the second layer 3a ₂ and the third layer 3a ₃ are all preferably formed by electroless plating containing nickel, copper and formaldehyde, and in one building tub It is more preferable that they are sequentially formed in the electroless plating solution. By sequentially forming a plurality of layers in one building tub, it is possible to maintain good adhesion between the respective layers.

As the composition of the electroless plating solution for continuously producing the first layer 3a ₁ , the second layer 3a ₂ and the third layer 3a ₃ with the same electroless plating solution, for example, (a) sulfuric acid Water-soluble copper salts such as copper; (b) water-soluble nickel salts such as nickel sulfate; (c) reducing agents such as formaldehyde; (d) complexing agents such as Rochelle salts and EDTA; and (e) alkali hydroxides. What added pH adjusters, such as these, is preferable.

In order to form the metal layer 3 on the surface of the resin particle 2a by electroless plating, for example, a palladium catalyst is applied to the surface of the resin particle 2a, and then a plating film is formed by performing electroless plating. Good. As a specific method for forming the first layer 3a ₁ , the second layer 3a ₂ and the third layer 3a ₃ by electroless plating, for example, (a) a water-soluble copper salt such as copper sulfate, (b (1) A water-soluble nickel salt such as nickel sulfate, (c) a reducing agent such as formaldehyde, (d) a complexing agent such as Rochelle salt and EDTA, and (e) a pH adjusting agent such as alkali hydroxide. By adding resin particles imparted with a palladium catalyst to the liquid, the first layer 3a ₁ and the second layer 3a ₂ are formed, and then (a) a water-soluble copper salt such as copper sulfate, (c) formaldehyde The third layer 3a ₃ is formed by replenishing a replenisher containing a reducing agent such as (d) a complexing agent such as Rochelle salt and EDTA, and (e) a pH adjusting agent such as alkali hydroxide. It becomes possible to do.

  (A) a water-soluble copper salt such as copper sulfate, (b) a water-soluble nickel salt such as nickel sulfate, (c) a reducing agent such as formaldehyde, (d) a complexing agent such as Rochelle salt, EDTA, and (e ) The concentration of the water-soluble nickel salt such as (b) nickel sulfate in the building bath solution to which a pH adjusting agent such as alkali hydroxide is added is preferably 0.0005 to 0.05 mol / L, 0.001 to 0 0.03 mol / L is more preferable, and 0.005 to 0.02 mol / L is more preferable. (B) When the concentration of the water-soluble nickel salt such as nickel sulfate is lower than 0.0005 mol / L, the palladium catalyst on the surface of the resin particle 2a cannot be covered with the nickel plating film, and the copper is deposited on the palladium catalyst. The part where the metal precipitates is likely to appear partially, the particles are easily aggregated, and the part where the metal is not precipitated is easily generated on a part of the surface of the resin particle 2a. (B) When the concentration of the water-soluble nickel salt such as nickel sulfate is higher than 0.05 mol / L, the activity of the liquid is increased by the increase in the nickel concentration, and the aggregation of particles tends to occur.

(A) a water-soluble copper salt such as copper sulfate, (b) a water-soluble nickel salt such as nickel sulfate, (c) a reducing agent such as formaldehyde, (d) a complexing agent such as Rochelle salt, EDTA, and (e ) The concentration of the water-soluble copper salt such as copper sulfate (a) in the building bath solution to which a pH adjusting agent such as alkali hydroxide is added is preferably 0.0005 to 0.05 mol / L, 0.001 to 0 0.03 mol / L is more preferable, and 0.005 to 0.02 mol / L is more preferable. (A) When the concentration of the water-soluble copper salt such as copper sulfate is lower than 0.0005 mol / L, the formation of the second layer 3a ₂ or the third layer 3a ₃ tends to be non-uniform. (A) When the concentration of the water-soluble copper salt such as copper sulfate is higher than 0.05 mol / L, the activity of the liquid increases and the aggregation of particles tends to occur due to the increase in the concentration of copper.

By including (a) a water-soluble copper salt such as copper sulfate and (b) a water-soluble nickel salt such as nickel sulfate in the electroless plating solution at the same time, the first layer 3a ₁ and the second layer 3a ₂ are formed. It can be continuously produced with the same electroless plating solution. The reason is considered as follows. That is, by using formaldehyde as a reducing agent, nickel is preferentially precipitated over copper on the palladium catalyst on the resin surface, so that the first layer 3a ₁ is formed, and then the first layer 3a ₁ The second layer 3a ₂ is formed on the outside. The second layer 3a _2, the ratio of the concentration of copper to nickel, tends to increase with the growth of the second layer 3a ₂ thickness. On the palladium catalyst, nickel is preferentially deposited, and when the palladium catalyst is coated with nickel, copper is immediately deposited. Therefore, a layer containing an alloy containing nickel and copper as a main component (the second layer) It is believed that layer 3a ₂ ) begins to form. And since the influence of a palladium catalyst becomes thin as the thickness of a plating film (Ni-Cu layer 3a) becomes thick, the precipitation of copper becomes more dominant than the precipitation of nickel, and as a result, the resin particle 2a side From the above, it is considered that the copper ratio increases in the thickness direction in the plating film.

If the surface of the resin particles 2a to form a first layer 3a _1, it can be compared with the case of forming the direct copper plating layer on the surface of the resin particles 2a, to suppress the aggregation of the resin particles 2a. The reason is considered as follows. The deposition process from copper ions to copper in electroless copper plating is a reaction in which the valence of copper changes from Cu (divalent) → Cu (monovalent) → Cu (zero valent), and is not suitable as a reaction intermediate. Stable monovalent copper ions are produced. This monovalent copper ion causes a disproportionation reaction, for example, Cu (zero valence) is generated in the plating solution, and the stability of the solution is considered to be very low. On the other hand, the deposition process from nickel ions to nickel in electroless nickel plating is a reaction in which the valence of nickel changes from Ni (divalent) to Ni (zero valent), and is an unstable monovalent as a reaction intermediate. Does not pass through the nickel ion process. Therefore, when comparing electroless copper plating and electroless nickel plating on the surface of the palladium catalyst, the electroless copper plating solution is less stable and the reaction is more intense. It becomes easy to do. On the other hand, as described above, electroless nickel plating has high stability, and it is considered that a plating film can be formed while suppressing aggregation of particles.

  The reason why the pinholes are generated in the metal layer 3 of the conductive particles 2 is considered to be because the particles aggregate when forming the plating film. The present inventors infer about this as follows. That is, if the particles aggregate in the initial stage of plating, and then the particles are separated from each other, plating was not performed in the initial stage where it was agglomerated. And pinholes are formed. In addition, when the conductive particles 2 in which pinholes are formed are compressed, it is considered that the electric resistance value increases because cracks in the plating film are likely to occur starting from the pinhole formation portion.

Next, the reaction of electroless copper plating on the surface of the palladium catalyst on the surface of the resin particle 2a, the reaction of the second layer 3a ₂ on the first layer 3a ₁ , and the reaction of the second layer 3a ₂ on the second layer 3a ₂ 3 the reaction and the layers 3a _3, discussed by comparing growth of the third layer 3a _3, four's.

In the electroless copper plating reaction on the surface of the palladium catalyst on the surface of the resin particle 2a, the oxidation reaction of a reducing agent such as formaldehyde tends to proceed on the palladium catalyst surface. It stabilizes and the particles tend to aggregate. On the other hand, in the reaction of the second layer 3a ₂ in the first layer 3a on _one, the first layer 3a ₁ is the surface of the autocatalytic reducing agent is oxidized. In the reaction of the third layer 3a _{3 on} the surface of the _second layer 3a ₂ , the second layer 3a ₂ becomes the surface of the autocatalyst, and the reducing agent is oxidized. Further, the growth of the third layer 3a _3, copper itself is a surface of the autocatalytic growth of the copper occurs. When the oxidation reaction of a reducing agent such as formaldehyde on the surfaces of the first layer 3a ₁ , the second layer 3a ₂ and the third layer 3a ₃ is compared with the oxidation reaction of a reducing agent such as formaldehyde on the surface of the palladium catalyst, The oxidation reaction of a reducing agent such as formaldehyde on the surfaces of the first layer 3a ₁ , the second layer 3a ₂ and the third layer 3a ₃ is less likely to proceed than on the palladium catalyst surface. Therefore, in electroless copper plating on the surface of the palladium catalyst, particles tend to aggregate, but even if nickel-copper alloy or copper coating grows, the particles hardly aggregate.

As a reducing agent for the electroless plating solution used in this embodiment, for example, a reducing agent such as sodium hypophosphite, sodium borohydride, dimethylamine borane, hydrazine may be used, but formaldehyde is used alone. Most preferred. When adding sodium hypophosphite, sodium borohydride, dimethylamine borane, etc., since phosphorus and boron are likely to co-deposit, the nickel content in the first layer 3a ₁ is set to 97% by weight or more. For this, it is preferable to adjust the concentration. By using formaldehyde as the reducing agent, it is easy to form a plating film having a nickel content of 99% by weight or more in the first layer 3a ₁ . In this case, when the conductive particles 2 are highly compressed and crimped and connected, it is possible to suppress cracking of the metal after compression. On the other hand, when the nickel content in the first layer 3a ₁ is lower than 97% by weight, cracking of the metal after compression tends to occur. When a reducing agent such as sodium hypophosphite, sodium borohydride, dimethylamine borane, hydrazine is used, it is preferable to use at least one of these in combination with formaldehyde.

  Examples of complexing agents for the electroless plating solution used in the present embodiment include amino acids such as glycine, amines such as ethylenediamine and alkylamine, copper complexing agents such as EDTA and pyrophosphate, citric acid, tartaric acid, hydroxyacetic acid, Malic acid, lactic acid, gluconic acid and the like may be used.

  It is desirable that the washing with water after the electroless copper plating is completed efficiently in a short time. As the washing time is shorter, an oxide film is less likely to be formed on the copper surface, so that subsequent plating tends to be advantageous.

(4th layer, 5th layer, 6th layer)
As shown in FIG. 2A, the metal layer 3 of the conductive particle 2 may further include a fourth layer 4 containing nickel and not containing copper outside the Ni—Cu layer 3a.

The fourth layer 4 contains nickel and does not contain copper. The fourth layer 4 functions as a copper migration stop layer. Thus, the fourth layer 4 is preferably provided on the third layer 3a _3. The nickel content in the fourth layer 4 is preferably in the range of 85 to 99% by weight, more preferably in the range of 88 to 98% by weight, and still more preferably in the range of 90 to 97% by weight. When the nickel content is lower than 85% by weight, the depositing property of the nickel plating film on the surface of the third layer 3a ₃ is lowered, and there may be a place where the nickel is not partially deposited. If the nickel content is higher than 99% by weight, the magnetic properties of nickel increase, and the aggregation of the conductive particles 2 tends to occur.

The thickness of the fourth layer 4 is preferably in the range of 20 to 1000 mm (2 to 100 nm), more preferably in the range of 50 to 500 mm (5 to 50 nm), and further preferably in the range of 100 to 300 mm (10 to 30 nm). . If the thickness of the fourth layer 4 is less than 20 mm (2 nm), there may be a place where the copper surface of the third layer 3a ₃ is not covered, and copper diffuses and oxidizes on the nickel surface, resulting in conductivity. Tend to decrease. If it exceeds 1000 mm (100 nm), the conductive particles 2 tend to aggregate during plating.

  For example, the fourth layer 4 is a solution in which a water-soluble nickel salt such as nickel sulfate, a reducing agent such as sodium hypophosphite, a complexing agent such as Rochelle salt, and a pH adjusting agent such as alkali hydroxide are added. Can be formed. As the reducing agent, for example, a reducing agent such as sodium hypophosphite, sodium borohydride, dimethylamine borane, hydrazine may be used. From the viewpoint of the stability of the plating solution, sodium hypophosphite is used. It is preferable to use it alone. The complexing agent may be any complexing agent capable of complexing with nickel, and examples thereof include Rochelle salt, citric acid, hydroxyacetic acid, malic acid, and lactic acid.

In the conductive particle 2 of the present embodiment, the metal layer 3 may further include a fifth layer (hereinafter also simply referred to as “fifth layer”) 5 containing palladium outside the Ni—Cu layer 3 a. Good. The fifth layer 5 may be provided on the third layer 3a ₃ or on the fourth layer 4 (see FIG. 2B).

The fifth layer functions as a copper migration stop layer. Thus, the layer 5 of the fifth is preferably provided on the third layer 3a _3. The thickness of the fifth layer 5 is preferably 100 to 1000 mm (10 to 100 nm), more preferably 100 to 300 mm (10 to 30 nm). If the thickness of the fifth layer 5 is less than 100 mm (10 nm), the fifth layer 5 becomes sparse when the fifth layer 5 is formed by plating or the like, and the effect as a copper migration stop layer is reduced. Tend to. If the thickness of the fifth layer 5 exceeds 1000 mm (100 nm), the manufacturing cost tends to increase.

  The fifth layer 5 can be formed, for example, through a palladium plating step, and the fifth layer 5 is preferably an electroless plating type palladium layer. For electroless palladium plating, either a substitution type (a type that does not contain a reducing agent) or a reduction type (a type that contains a reducing agent) may be used. Examples of such electroless palladium plating include APP (product name) manufactured by Ishihara Pharmaceutical Co., Ltd. for the reduction type, and MCA (product name manufactured by World Metal Co., Ltd.) for the replacement type.

  When the substitution type and the reduction type are compared, the reduction type is particularly preferable because voids tend to decrease. Since the substitution type precipitates while dissolving the inner metal, the coating area is less likely to increase than the reduction type.

In the conductive particles 2 of the present embodiment, the metal layer 3 further includes a sixth layer 6 (hereinafter also simply referred to as “sixth layer”) 6 containing gold outside the Ni—Cu layer 3a. Also good. The sixth layer 6 may be provided on the third layer 3 a ₃ , may be provided on the fourth layer 4, or may be provided on the fifth layer 5 (FIG. 2 (c)).

  The sixth layer 6 reduces the electrical resistance value on the surface of the conductive particles and improves the characteristics. From this viewpoint, the sixth layer 6 is preferably formed as the outermost layer of the metal layer 3. In this case, the thickness of the sixth layer 6 is preferably more than 0 mm (0 nm) and not more than 300 mm (30 nm) from the viewpoint of the balance between the effect of reducing the electric resistance value on the surface of the conductive particles 2 and the manufacturing cost. However, there is no problem in characteristics even if it is 300 mm (30 nm) or more. Moreover, when the function as a copper migration stop layer is expected, the sixth layer 6 is preferably provided on the third layer 3. In this case, the thickness of the sixth layer 6 is preferably 100 to 1000 mm (10 to 100 nm).

  The sixth layer 6 can be formed through a gold plating process, for example. For the gold plating, for example, substitution type gold plating such as HGS-100 (manufactured by Hitachi Chemical Co., Ltd., trade name) or reduction type gold plating such as HGS-2000 (product name of Hitachi Chemical Co., Ltd.) is used. be able to.

  When the substitution type and the reduction type are compared, the reduction type is particularly preferable because voids tend to decrease. Since displacement plating precipitates while dissolving the inner metal, the coating area is less likely to increase compared to the reduced type.

<Insulation coated conductive particles>
Next, the insulating coated conductive particles of this embodiment will be described. Insulating coated conductive particles 10 shown in FIG. 3 are formed by covering at least part of the surface of the metal layer 3 of the conductive particles 2 with the insulating particles 1. In recent years, anisotropic conductive adhesives for COG mounting have been required to have insulation reliability at a narrow pitch of 10 μm level. Therefore, in order to further improve insulation reliability, it is preferable to apply an insulating coating to the conductive particles 2. . According to the insulating coated conductive particles 10, such required characteristics can be effectively realized.

  As the insulator particles 1 covering the conductive particles 2, inorganic oxide fine particles are preferable from the viewpoint of insulation reliability. When organic fine particles are used, the insulation reliability is difficult to improve as compared with the case of using inorganic oxide fine particles, but the insulation resistance value is likely to be lowered.

As the inorganic oxide fine particles, for example, an oxide containing at least one element selected from the group consisting of silicon, aluminum, zirconium, titanium, niobium, zinc, tin, cerium, and magnesium is preferable, and these may be used alone or in two kinds. The above can be mixed and used. Among the inorganic oxide fine particles, water-dispersed colloidal silica (SiO ₂ ) is particularly suitable because it has a hydroxyl group on the surface, and thus has excellent bonding properties with conductive particles, easily aligns the particle diameter, and is inexpensive. Examples of such commercially available inorganic oxide fine particles include Snowtex, Snowtex UP (trade name, manufactured by Nissan Chemical Industries, Ltd.), Quateron PL series (trade name, manufactured by Fuso Chemical Industries, Ltd.), and the like. It is done.

  As the size of the inorganic oxide fine particles, the average particle diameter measured by a specific surface area conversion method by the BET method or the X-ray small angle scattering method is preferably 20 to 500 nm. If this average particle size is less than 20 nm, the inorganic oxide fine particles adsorbed on the conductive particles do not act as an insulating film, and a short circuit tends to occur in part. When this average particle diameter exceeds 500 nm, the conductivity in the pressurizing direction of connection tends to decrease.

  The hydroxyl group on the surface of the inorganic oxide fine particle can be modified to an amino group, a carboxyl group, an epoxy group, etc. with a silane coupling agent, etc., but it is difficult if the average particle size of the inorganic oxide fine particle is 500 nm or less There is. In that case, it is desirable to coat the conductive particles without modification with a functional group.

  In general, by having a hydroxyl group, it can be bonded to a hydroxyl group, a carboxyl group, an alkoxyl group, an alkoxycarbonyl group, or the like. Examples of the bonding form include a covalent bond by dehydration condensation, a hydrogen bond, and a coordination bond.

  When the surface of the conductive particle 2 is made of gold or palladium, it is a compound having a mercapto group, sulfide group, disulfide group, or the like that forms a coordinate bond with these in the molecule, and has a hydroxyl group, carboxyl group, alkoxyl group, alkoxy group on the surface. A functional group such as a carbonyl group may be formed. Examples of the compound include mercaptoacetic acid, 2-mercaptoethanol, methyl mercaptoacetate, mercaptosuccinic acid, thioglycerin, and cysteine.

  In particular, noble metals such as gold, palladium, and copper easily react with thiol, and base metals such as nickel hardly react with thiol. That is, when the outermost layer of the conductive particles 2 is a noble metal, it reacts more easily with thiol than when the outermost layer of the conductive particles 2 is a base metal.

  For example, the method for treating the above compound on the gold surface is not particularly limited, but a compound such as mercaptoacetic acid is dispersed in an organic solvent such as methanol or ethanol at about 10 to 100 mmol / L, and the outermost layer is made of gold. A certain conductive particle 2 is dispersed.

  Next, as a method of coating the surface of the conductive particles 2 having functional groups with inorganic oxide fine particles, for example, a method of alternately laminating polymer electrolytes and inorganic oxide fine particles is preferable. As a more specific production method, (1) a step of dispersing conductive particles 2 having functional groups in a polymer electrolyte solution, adsorbing the polymer electrolyte on the surfaces of the conductive particles 2, and then rinsing, (2) The conductive particles 2 are dispersed in a dispersion solution of inorganic oxide fine particles, the inorganic fine particles are adsorbed on the surface of the conductive particles 2 and then rinsed, whereby the polymer electrolyte and the inorganic oxide fine particles are formed on the surface. The coated insulating coated conductive particles 10 can be manufactured. Such a method is called an alternating lamination method (Layer-by-Layer assembly). The alternate lamination method is described in G.H. This is a method of forming an organic thin film published in 1992 by Decher et al. (Thin Solid Films, 210/211, p831 (1992)). In this method, a polycation adsorbed on a substrate by electrostatic attraction by alternately immersing the base material in an aqueous solution of a polymer electrolyte having a positive charge (polycation) and a polymer electrolyte having a negative charge (polyanion). A combination of polyanions is laminated to obtain a composite film (alternate laminated film).

  In the alternating layering method, the film is grown by attracting the charge of the material formed on the substrate and the material having the opposite charge in the solution by electrostatic attraction, so that the adsorption proceeds and the charge is neutralized. When this occurs, no further adsorption occurs. Therefore, when reaching a certain saturation point, the film thickness does not increase any more. Lvov et al. Reported on a method of applying an alternate lamination method to fine particles and laminating a polymer electrolyte having a charge opposite to the surface charge of the fine particles using each fine particle dispersion such as silica, titania, and ceria. (Langmuir, Vol. 13, (1997) p6195-6203). By using this method, silica fine particles having a negative surface charge and polydiallyldimethylammonium chloride (PDDA) or polyethyleneimine (PEI), which are polycations having the opposite charge, are alternately laminated to form silica. It is possible to form a fine particle laminated thin film in which fine particles and a polymer electrolyte are alternately laminated.

  As the polymer electrolyte, for example, a polymer that is ionized in an aqueous solution and has a charged functional group in the main chain or side chain can be used. In this case, a polycation is preferably used. The polycation generally has a positively charged functional group such as polyamines, such as polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethylammonium chloride ( PDDA), polyvinyl pyridine (PVP), polylysine, polyacrylamide, a copolymer containing at least one of these, and the like can be used. Among the polymer electrolytes, polyethyleneimine is preferable because of its high charge density and strong binding force.

  The ratio (coverage) that the insulator particles 1 cover the surfaces of the conductive particles 2 is preferably 20 to 40%. From the viewpoint of achieving both maintenance of a low resistance value of the circuit connection body and excellent insulation between adjacent circuit electrodes, the coverage is more preferably 25 to 35%, and more preferably 28 to 32%. Further preferred. If the coverage is 20% or more, sufficient insulation between adjacent circuit electrodes can be secured, and if it is 40% or less, both the sufficiently low initial resistance value of the connection portion and the suppression of the increase in resistance value over time are both suppressed. Can be fully achieved. The coverage here is based on the following measured values obtained by observation with a differential scanning electron microscope (magnification 8000 times). That is, the coverage is a value calculated based on the respective particle diameters of the conductive particles 2 and the insulator particles 1 and the number of insulator particles 1 attached to one conductor particle 2.

The particle size of the conductive particles 2 is measured as follows. That is, one conductive particle is arbitrarily selected and observed with a differential scanning electron microscope to measure the maximum diameter and the minimum diameter. The square root of the product of the maximum diameter and the minimum diameter is defined as the particle diameter of the particle. The particle diameter of 300 arbitrarily selected core particles is measured as described above, and the average value is defined as the average particle diameter (D ₁ ) of the conductive particles 2. As for the particle size of the insulator particles 1, the particle size of 300 arbitrary insulator particles is measured in the same manner, and the average value is defined as the average particle size (D ₂ ) of the insulator particles 1.

  The number of insulator particles 1 included in one conductive particle 2 is measured as follows. That is, one conductive particle whose surface is partially covered with a plurality of insulator particles is arbitrarily selected. And this is imaged with a differential scanning electron microscope, and the number of the insulating particles adhering to the surface of the core particle which can be observed is counted. By doubling the count number obtained in this way, the number of insulator particles attached to one conductive particle is calculated. The number of insulator particles is measured as described above for 300 arbitrarily selected conductive particles, and the average value is defined as the number of insulator particles included in one conductive particle.

<Anisotropic conductive adhesive>
The anisotropic conductive adhesive 50 can be produced by containing the conductive particles 2 or the insulating coated conductive particles 10 produced as described above in an adhesive. The anisotropic conductive adhesive 50 includes an adhesive component 20 having insulating properties, and conductive particles 2 or insulating coated conductive particles 10 dispersed in the adhesive component 20 (see FIG. 4). The anisotropic conductive adhesive 50 can be used as a circuit connecting material.

  As the adhesive component 20 used for the anisotropic conductive adhesive of this embodiment, for example, a mixture of a heat-reactive resin and a curing agent is used. Examples of the adhesive preferably used include (a) a mixture of an epoxy resin and (b) a latent curing agent, (c) a mixture of a radical polymerizable compound and (d) an organic peroxide, and the like.

  (A) As an epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolak type epoxy Examples thereof include resins, alicyclic epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, and aliphatic chain epoxy resins. These epoxy resins may be halogenated or hydrogenated. These epoxy resins can be used individually by 1 type or in combination of 2 or more types.

  (B) Examples of latent curing agents include amines, phenols, acid anhydrides, imidazoles, hydrazides, dicyandiamide, boron trifluoride-amine complexes, sulfonium salts, iodonium salts, amine imides, and the like. These can be used alone or in admixture of two or more, and may be used by mixing a decomposition accelerator, an inhibitor and the like. (B) The blending amount of the latent curing agent is preferably about 0.1 to 60.0% by mass and more preferably 1.0 to 20.0% by mass based on the total mass of the adhesive component. preferable. When the blending amount of the curing agent is less than 0.1% by mass, the progress of the curing reaction becomes insufficient, and it tends to be difficult to obtain good adhesive strength and connection resistance value. On the other hand, when the blending amount exceeds 60% by mass, the fluidity of the adhesive component tends to be reduced, the pot life tends to be shortened, and the connection resistance value of the connection portion tends to be high.

  (C) A radically polymerizable compound is a compound having a functional group that is polymerized by radicals, and examples thereof include (meth) acrylates and maleimide compounds.

  Examples of the organic peroxide (d) include diacyl peroxide, peroxydicarbonate, peroxyester, peroxyketal, dialkyl peroxide, hydroperoxide, and the like. (D) The compounding amount of the organic peroxide is preferably 0.05 to 10% by mass and more preferably 0.1 to 5% by mass based on the total mass of the adhesive component.

  The anisotropic conductive adhesive 50 may be a paste or processed into a film. In order to form a film, it is effective to blend a thermoplastic resin such as a phenoxy resin, a polyester resin, a polyamide resin, a polyester resin, a polyurethane resin, an acrylic resin, or a polyester urethane resin. The blending amount of these resins is preferably 2 to 80% by mass, more preferably 5 to 70% by mass, and 10 to 60% by mass based on the total mass of the adhesive component. Further preferred.

  In the anisotropic conductive adhesive 50, the content of the conductive particles 2 or the insulating coated conductive particles 10 is preferably 0.5 to 60 parts by volume when the total volume of the adhesive is 100 parts by volume, and the content thereof The amount depends on the application.

<Method for manufacturing connection structure>
A connection structure manufactured using the anisotropic conductive adhesive produced as described above and a method for manufacturing the connection structure will be described with reference to FIGS. 3 and 4.

[Connection structure]
The connection structure 100 shown in FIG. 3 includes a first circuit member 30 and a second circuit member 40 that face each other, and the connection between the first circuit member 30 and the second circuit member 40. A connecting portion 50a for connecting them is provided.

  The first circuit member 30 includes a circuit board (first circuit board) 31 and a circuit electrode (first circuit electrode) 32 formed on the main surface 31 a of the circuit board 31. The second circuit member 40 includes a circuit board (second circuit board) 41 and a circuit electrode (second circuit electrode) 42 formed on the main surface 41 a of the circuit board 41.

  Specific examples of the circuit member include a chip component such as an IC chip (semiconductor chip), a resistor chip, a capacitor chip, and a driver IC, a rigid package substrate, and the like. These circuit members are provided with circuit electrodes, and generally have many circuit electrodes. Specific examples of the other circuit member to which the circuit member is connected include a flexible tape substrate having metal wiring, a flexible printed wiring board, and a wiring substrate such as a glass substrate on which indium tin oxide (ITO) is deposited. Can be mentioned. According to the film-like anisotropic conductive adhesive 50, these circuit members can be connected efficiently and with high connection reliability. The anisotropic conductive adhesive of this embodiment is suitable for COG mounting or COF mounting on a wiring board of a chip component having many fine circuit electrodes.

  The connecting portion 50a includes a cured product 20a of an insulating adhesive contained in the anisotropic conductive adhesive, and insulating coated conductive particles 10 dispersed therein. And in the connection structure 100, the circuit electrode 32 and the circuit electrode 42 which oppose are electrically connected through the insulation coating electrically-conductive particle 10. FIG. More specifically, as shown in FIG. 3, in the insulating coated conductive particles 10, the conductive particles 2 are deformed by compression and are in direct contact with both the circuit electrodes 32 and 42. On the other hand, in the illustrated horizontal direction, insulation is maintained by the presence of the insulator particles 1 between the conductive particles 2. Therefore, if the anisotropic conductive adhesive of this embodiment is used, it is possible to improve the insulation reliability at a narrow pitch of 10 μm level. Further, depending on the application, it is also possible to use conductive particles that are not covered with insulation instead of insulating coated conductive particles.

[Method of manufacturing connection structure]
FIG. 4 is a process diagram showing a schematic cross-sectional view of a process for manufacturing the connection structure using an anisotropic conductive adhesive. In the present embodiment, the anisotropic conductive adhesive is thermoset to produce a connection structure.

  First, the first circuit member 30 described above and the anisotropic conductive adhesive 50 formed into a film shape are prepared. The film-like anisotropic conductive adhesive 50 is obtained by containing the insulating coated conductive particles 10 in the insulating adhesive component 20 as described above.

  Next, the film-like anisotropic conductive adhesive 50 is placed on the surface of the first circuit member 30 on which the circuit electrodes 32 are formed. Then, the film-like anisotropic conductive adhesive 50 is pressed in the directions of arrows A and B in FIG. 4A, and the film-like anisotropic conductive adhesive 50 is laminated on the first circuit member 30 ( FIG. 4 (b)).

  Next, as shown in FIG. 4C, the film-like anisotropic conductive adhesive 50 is arranged so that the second circuit member 40 faces the second circuit electrode 42 toward the first circuit member 30. Put it on top. Then, while the film-like anisotropic conductive adhesive 50 is heated, the whole is pressurized in the directions of arrows A and B in FIG. The connection portion 50a is formed by curing the film-like anisotropic conductive adhesive 50, and a connection structure 100 as shown in FIG. 3 is obtained.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to the following Example.

<Example 1>
(Process a) (Pretreatment process)
2 g of crosslinked polystyrene particles having an average particle size of 3.8 μm are added to 100 mL of a palladium-catalyzed solution containing 8 wt% of Atotech Neogant 834 (trade name, manufactured by Atotech Japan Co., Ltd.), which is a palladium catalyst, and 30 minutes at 30 ° C. After stirring, the solution was filtered through a membrane filter of φ3 μm (Millipore Corporation) and washed with water. Thereafter, the resin particles were added to a 0.5 wt% dimethylamine borane solution adjusted to pH 6.0 to obtain resin particles whose surface was activated. Thereafter, the resin particles whose surfaces were activated were immersed in 20 mL of distilled water and ultrasonically dispersed.

(Process b) (Plating process)
Thereafter, resin particles are added to 1 L of a building bath liquid having a composition shown in Table 1 heated to 40 ° C., and a first layer containing 97% by weight or more of the value shown in Table 2; and A second layer containing an alloy mainly composed of nickel and copper was formed. Further, 930 mL of replenisher A and replenisher B not containing nickel having the following composition were prepared by the addition method, and continuously dropped at a rate of 20 mL / min, and the copper having the content and thickness shown in Table 2 was added. A third layer as a main component was formed.
(Replenisher A)
_{CuSO 4 · 5H 2 O: 0.8mol} / L
HCHO: 1 mol / L
NaCN: 0.001 mol / L
(Replenisher B)
EDTA · 4Na: 1 mol / L
NaOH: 1 mol / L

  After washing with water and filtering, the conductive particles are immersed in HGS-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.) at 85 ° C., which is a displacement gold plating, and the gold film having the thickness shown in Table 2 is contained. 6 layers were formed to produce conductive particles.

(Evaluation of film thickness and components of conductive particles)
About the obtained electroconductive particle, the cross section was cut out with the focused ion beam, and it observed with the transmission electron microscope of 400,000 times. At this time, the components of the first layer, the second layer, and the third layer are analyzed by component analysis using EDX (energy dispersive X-ray spectrometer, manufactured by JEOL Datum Co., Ltd.) and the film thickness is determined. Measured. The measurement results are shown in FIG. The film thickness was also measured for the sixth layer containing gold.

(Method for measuring resistance value of conductive particles)
Using a micro compression tester MCTW-200 (manufactured by Shimadzu Corporation, trade name), the conductive particles were compressed under the condition of a load speed of 0.5 mN / sec and compressed to 70% of the original particle size. In case (compression rate 30%), when compressed to 50% of original particle size (compression rate 50%), compressed to 40% of original particle size (compression rate 60%), original When compressed to 30% of the particle size (compression rate 70%), compressed to 20% of the original particle size (compression rate 80%), and until 10% of the original particle size The electrical resistance value (Ω) when compressed (compression ratio 90%) was measured. Ten conductive particles were measured, and the average value is shown in Table 5.

(Evaluation of cohesiveness by plating of conductive particles)
The obtained conductive particles were crushed, 300 conductive particles were observed with an SEM, the ratio of the number of conductive particles in which pinholes were generated in the plating film was calculated as the pinhole generation rate, and the cohesiveness evaluation by plating was evaluated. Went. The results are shown in Table 5. The conductive particles were crushed as follows. That is, 1 g of conductive particles, 40 g of zirconia balls having a diameter of 1 mm, and 20 mL of ethanol were put into a 100 mL beaker. The liquid in the beaker was stirred for 2 minutes at a rotational speed of 400 rpm using four stainless steel stirring blades, and then filtered and dried. The electroconductive particle which passed through these processes was observed by SEM.

<Example 2>
In the plating step of Example 1 (step b), all except that the bathing solution was changed to the bathing solution shown in Table 1 and that the replenishers A and B not containing nickel were changed to 830 mL, respectively. The same operation as in Example 1 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Example 3>
In the plating step of Example 1 (step b), all except that the bathing solution was changed to the bathing solution shown in Table 1 and that the replenishers A and B not containing nickel were each changed to 800 mL. The same operation as in Example 1 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Example 4>
In the plating step of Example 1 (step b), all except that the bath solution was changed to the bath solution shown in Table 1 and that the replenishers A and B not containing nickel were changed to 730 mL, respectively. The same operation as in Example 1 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Example 5>
In the plating step of Example 1 (step b), all except that the bath solution was changed to the bath solution shown in Table 1 and that the replenishers A and B not containing nickel were each changed to 700 mL. The same operation as in Example 1 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Example 6>
In the plating step of Example 1 (step b), all except that the bathing solution was changed to the bathing solution shown in Table 1 and that the replenishers A and B not containing nickel were changed to 670 mL, respectively. The same operation as in Example 1 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative Example 1>
In the plating process of Example 1 (step b), all was performed in the same manner as in Example 1 except that the bath solution was changed to the bath solution shown in Table 1. As in Example 1, Table 5 shows the measurement result of the electrical resistance value (Ω) with respect to the compression rate and the calculation result of the pinhole generation rate (%) after crushing.

<Comparative example 2>
In the plating process of Example 1 (step b), all was performed in the same manner as in Example 1 except that the bath solution was changed to the bath solution shown in Table 1. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative Example 3>
In the plating process of Example 1 (step b), all was performed in the same manner as in Example 1 except that the bath solution was changed to the bath solution shown in Table 1. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative example 4>
In the plating process of Example 1 (step b), all was performed in the same manner as in Example 1 except that the bath solution was changed to the bath solution shown in Table 1. As in Example 1, the measurement results of the film thickness are shown in Table 2, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative Example 5>
The pretreatment step of (Step a) of Example 1 was performed. Thereafter, a solution containing 0.084 mol / L (1% by weight) of succinic acid was prepared, the resin particles subjected to the pretreatment step were added, and sulfuric acid was further added to prepare 1 L of a resin particle-containing solution having a pH of 5.

In order to produce a seventh layer alloy plating film containing nickel and phosphorus, a plating solution having the following composition was prepared.
(Electroless plating solution for preparing the seventh layer containing nickel and phosphorus)
_{NiSO 4 · 6H 2 O: 0.76mol} / L (20 wt%)
_{NaPO 2 · H 2 O: 1.89mol} / L (20 wt%)
NaOH: 2 mol / L (8% by weight)

  1 L of the obtained resin particle-containing solution was brought to 80 ° C., and 20 mL of a seventh layer-forming electroless plating solution containing nickel and phosphorus was continuously dropped at a rate of 20 mL / min. A layer was obtained.

Next, in order to produce the 8th layer alloy plating film containing nickel, copper, and phosphorus, the plating solution of the following composition was prepared.
(Electroless plating solution for preparing the eighth layer containing nickel, copper and phosphorus)
_{NiSO 4 · 6H 2 O: 0.76mol} / L (20 wt%)
_{CuSO 4 · 5H 2 O: 0.80mol} / L (20 wt%)
NaH ₂ PO ₂ .H ₂ O: 1.89 mol / L (20% by weight)
NaOH: 2 mol / L (8% by weight)

  Thereafter, 980 mL of the plating solution for preparing the alloy plating of the obtained eighth layer was continuously dropped at a rate of 20 mL / min into the solution where the preparation of the seventh layer was finished. 8 layers were obtained.

  After washing with water and filtration, the conductive particles were immersed in HGS-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.) at 85 ° C., which is a displacement gold plating, and the gold film having the thickness shown in Table 3 is contained. 6 layers were formed to produce conductive particles. As in Example 1, the measurement results of the film thickness are shown in Table 3, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative Example 6>
In Comparative Example 5, the seventh layer preparation electroless plating solution was changed to 50 mL, and the eighth layer preparation electroless plating solution was changed to 950 mL, and the thicknesses of the seventh layer and the eighth layer were changed. Except for this, the same procedure as in Comparative Example 5 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 3, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative Example 7>
In Comparative Example 5, the electroless plating solution for preparing the seventh layer was changed to 100 mL and the electroless plating solution for preparing the eighth layer was changed to 900 mL, and the thicknesses of the seventh layer and the eighth layer were changed. Except for this, the same procedure as in Comparative Example 5 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 3, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative Example 8>
The thickness of the seventh layer and the eighth layer was changed by changing the electroless plating solution for preparing the seventh layer in Comparative Example 5 to 200 mL and the electroless plating solution for preparing the eighth layer to 800 mL, respectively. Except for this, the same procedure as in Comparative Example 5 was performed. As in Example 1, the measurement results of the film thickness are shown in Table 3, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

<Comparative Example 9>
The same operation as in Comparative Example 5 was performed to form a seventh layer containing nickel and phosphorus, and then washed with water and filtered. 1 L of the obtained conductive particle-containing solution was brought to 40 ° C., and 980 mL of replenishers A and B each containing no nickel having the following composition were prepared by the addition method, and continuously dropped at a rate of 20 mL / min. A third layer having the value shown in FIG.
(Replenisher A)
_{CuSO 4 · 5H 2 O: 0.8mol} / L
HCHO: 1 mol / L
NaCN: 0.001 mol / L
(Replenisher B)
EDTA · 4Na: 1 mol / L
NaOH: 1 mol / L

  After washing with water and filtering, the conductive particles are immersed in 85 ° C HGS-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a displacement gold plating, and a sixth layer containing gold is formed. Particles were made. As in Example 1, the measurement results of the film thickness are shown in Table 4, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

(Comparative Example 10)
By performing the same operation as in Comparative Example 6, the seventh layer shown in Table 4 was formed, and 950 mL of replenishing solutions A and B that did not contain nickel were also prepared in the same manner as in Comparative Example 9, and 20 mL / min. The third layer having the values shown in Table 4 was formed by continuous dropwise addition at a rate of. Further, a sixth layer was formed in the same manner as in Comparative Example 9. As in Example 1, the measurement results of the film thickness are shown in Table 4, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

(Comparative Example 11)
By performing the same operation as in Comparative Example 7, the seventh layer shown in Table 4 was formed, and 900 mL of replenishers A and B containing no nickel as in Comparative Example 9 were prepared, and 20 mL / min. The third layer having the values shown in Table 4 was formed by continuous dropwise addition at a rate of. Further, a sixth layer was formed in the same manner as in Comparative Example 9. As in Example 1, the measurement results of the film thickness are shown in Table 4, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

(Comparative Example 12)
By performing the same operations as in Comparative Example 8, the seventh layer shown in Table 4 was formed, and 800 mL of replenishers A and B that did not contain nickel were also prepared, and 20 mL / min. The third layer having the values shown in Table 4 was formed by continuous dropwise addition at a rate of. Further, a sixth layer was formed in the same manner as in Comparative Example 9. As in Example 1, the measurement results of the film thickness are shown in Table 4, and the measurement results of the electrical resistance value (Ω) with respect to the compression rate and the calculation results of the pinhole occurrence rate (%) after crushing are shown in Table 5.

  From the above results, the conductive particles produced in Examples 1 to 6 have a resistance value of 5Ω or less even when the compression rate is 90% (that is, the compression is performed until the size becomes 10% of the original particle size). It became clear that it can be maintained. Moreover, even if it looked at the pinhole incidence after crushing, it was 0%, and it turned out that the aggregation between the particles in the middle of plating can be suppressed. On the other hand, even if formaldehyde is used as the reducing agent, conductive particles produced by the method of Comparative Example 1 that does not contain nickel in the initial bathing solution of plating deposition, and comparison using hypophosphorous acid instead of formaldehyde as the reducing agent It was found that the conductive particles produced in Examples 2 to 4 increased in electrical resistance when compressed, and exceeded 5Ω when the compression ratio was 80%. Moreover, when the pinhole incidence after crushing was seen, it turned out that it has generate | occur | produced in the ratio around 10%. Since the conductive particles produced in Comparative Examples 5 to 12 do not have pinholes after crushing, the formation of a plating film containing nickel and phosphorus at the initial stage of plating deposition causes aggregation between particles during plating. It was found that the electrical resistance value accompanying compression tends to increase as the thickness of the plating film containing nickel and phosphorus increases.

  ADVANTAGE OF THE INVENTION According to this invention, even when it compresses, a low electrical resistance value can be maintained, and the conductive particle with few pinholes and the insulation coating conductive particle using the same are provided. Moreover, according to this invention, the anisotropic conductive adhesive containing the said electroconductive particle or insulation coating electroconductive particle is provided. Furthermore, according to this invention, the method of manufacturing a connection structure using the said anisotropic conductive adhesive, and the connection structure manufactured by this are provided.

DESCRIPTION OF SYMBOLS 1 ... Insulator child particle, 2 ... Conductive particle, 2a ... Resin particle, 3 ... Metal layer, 3a ... Ni-Cu layer, 3a ₁ ... 1st layer (1st part), 3a ₂ ... 2nd layer ( 2nd part), 3a ₃ ... 3rd layer (3rd part), 4 ... 4th layer, 5 ... 5th layer, 6 ... 6th layer, 10 ... Insulation coated conductive particles, 20 ... Insulating adhesive component, 20a ... cured product of insulating adhesive component, 30 ... first circuit member, 31 ... circuit board (first circuit board), 31a ... main surface of first circuit board, 32 ... Circuit electrode (first circuit electrode), 40 ... Second circuit member, 41 ... Circuit board (second circuit board), 41a ... Main surface of the second circuit board, 42 ... Circuit electrode (second) Circuit electrode), 50... Film-like anisotropic conductive adhesive, 50 a... Connection part, 100.

Claims (17)

Resin particles and a metal layer provided on the surface of the resin particles,
The metal layer having at least a including Ni-Cu layer of nickel and copper,
The Ni—Cu layer is a first portion containing 97% by weight or more of nickel in order closer to the resin particles, and a second portion in which the element ratio of copper to nickel increases as the distance from the surface of the resin particles increases . and, Rushirubeden particles from the third portion are arranged structure containing copper. The sum of the content and the copper content of the nickel in the second portion is 97 wt% or more, the conductive particle according to claim 1. The electroconductive particle of Claim 1 or 2 whose content rate of the copper in a said 3rd part is 97 weight% or more. Said first portion, said second portion and said third portion, nickel, and is formed by an electroless plating solution containing copper and formaldehyde, according to any one of claims 1 to 3 Conductive particles. The conductive particles according to claim 4 , wherein the first portion and the second portion are sequentially formed in an electroless plating solution in one building tub. The metal layer, the outside of the Ni-Cu layer further includes a fourth layer containing no copper containing nickel, conductive particles according to any one of claims 1 to 5. The electroconductive particle of Claim 6 whose content rate of the nickel in a said 4th layer is 85 to 99 weight%. The metal layer, the outside of the Ni-Cu layer, further comprising a fifth layer containing palladium, conductive particles according to any one of claims 1 to 7. The metal layer, the outside of the Ni-Cu layer, having further a sixth layer containing gold, conductive particles according to any one of claims 1-8. Average particle size of 1 to 10 [mu] m, the conductive particles according to any one of claims 1-9. Average particle diameter of 2 to 5 [mu] m, the conductive particles according to any one of claims 1-9. Conductive particles according to any one of claims 1 to 11 ,
Insulator particles provided on the surface of the metal layer of the conductive particles and covering at least a part of the surface;
Insulating coated conductive particles. An anisotropic conductive adhesive comprising the conductive particles according to any one of claims 1 to 11 in an adhesive. An anisotropic conductive adhesive comprising the insulating coated conductive particles according to claim 12 in an adhesive. A first circuit member having a plurality of first circuit electrodes formed on the main surface of the first circuit board;
A second circuit member having a plurality of second circuit electrodes formed on the main surface of the second circuit board;
The first and second circuit electrodes are provided between the main surface of the first circuit board and the main surface of the second circuit board, and the first and second circuit electrodes face each other. A circuit connecting member for connecting two circuit members;
A circuit member connection structure comprising:
The circuit connection member is made of a cured product of the anisotropic conductive adhesive according to claim 13 ,
A connection structure for a circuit member, wherein the first circuit electrode and the second circuit electrode are electrically connected via the conductive particles. A first circuit member having a plurality of first circuit electrodes formed on the main surface of the first circuit board;
A second circuit member having a plurality of second circuit electrodes formed on the main surface of the second circuit board;
The first and second circuit electrodes are provided between the main surface of the first circuit board and the main surface of the second circuit board, and the first and second circuit electrodes face each other. A circuit connecting member for connecting two circuit members;
A circuit member connection structure comprising:
The circuit connection member comprises a cured product of the anisotropic conductive adhesive according to claim 14 ,
A connection structure for a circuit member, wherein the first circuit electrode and the second circuit electrode are electrically connected via the insulating coating conductive particles. A first circuit member having a plurality of first circuit electrodes formed on a main surface of the first circuit board; and a second circuit member having a plurality of second circuit electrodes formed on a main surface of the second circuit board. A step of interposing the anisotropic conductive adhesive according to claim 13 or 14 with the first circuit electrode and the second circuit electrode opposed to each other between two circuit members;
Curing the anisotropic conductive adhesive by heating and pressing; and
The manufacturing method of the connection structure of a circuit member provided with this.

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