JP2011150836A - Circuit connection member, conductive particles, and manufacturing method of conductive particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit connection member with substantial indentation resistance. <P>SOLUTION: There is provided a sheet-shaped circuit connection member formed of a sheet-forming material containing a polymer material and conductive particles, the conductive particle having at least one flat-face part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a circuit connecting member, conductive particles, and a method for producing conductive particles. More specifically, circuit connection members, such as anisotropic conductive sheets and anisotropic conductive connectors, which are preferably used as electrical connections between circuit elements and connectors in printed circuit board inspection apparatuses, conductive particles used therein and conductive The present invention relates to a method for producing conductive particles.

  An anisotropic conductive sheet exhibits conductivity only in the thickness direction, or exhibits conductivity only in the thickness direction when pressed in the thickness direction. Anisotropic conductive sheets can be compactly connected without using soldering or mechanical fitting, and have soft connections that absorb mechanical shocks and strains. Features such as being possible. For this reason, anisotropic conductive sheets are used in the fields of electronic calculators, electronic digital watches, electronic cameras, computer keyboards, etc., as electrical elements between circuit elements such as printed circuit boards and leadless chip carriers, liquid crystal panels, etc. Widely used as a connector for realizing connection.

  In an electrical inspection of a circuit board such as a printed circuit board, an electrical connection between an electrode to be inspected formed on one surface of the circuit board to be inspected and an electrode for connection formed on the surface of the circuit board for inspection In order to make the connection, an anisotropic conductive sheet is interposed between the inspected electrode region of the circuit board and the connecting electrode region of the circuit board for inspection.

Conventionally, what has various composition is known as such an anisotropically conductive sheet. Patent Document 1 discloses an anisotropic conductive sheet containing conductive particles coated with a conductive metal in a state of being oriented in the thickness direction. Patent Document 2 discloses an anisotropic conductive sheet characterized in that the insulating sheet body is made of an elastic polymer material having a small thermal expansion coefficient. Patent Document 3 discloses that conductive particles contained in an anisotropic conductive sheet are conductive particles A having a number average particle diameter of a [μm] and conductive particles having a number average particle diameter of b [μm]. The particle diameter ratio (a / b) between the number average particle diameter a [μm] of the conductive particles A and the number average particle diameter b [μm] of the conductive particles B is obtained. An anisotropic conductive sheet having 4 to 9 is disclosed. Patent Document 4 discloses an anisotropic conductive sheet characterized in that a lubricant or a release agent is applied to the surface of conductive particles contained in the anisotropic conductive sheet. In Patent Document 5, the conductive particles contained in the anisotropic conductive sheet have a number average particle diameter of 5 to 100 μm and a BET specific surface area of 0.01 × 10 ^{3 to} 0.7 × 10 ³ m ² / kg. An anisotropic conductive sheet characterized by a sulfur element concentration of 0.1% by mass or less, an oxygen element concentration of 0.5% by mass or less, and a carbon element concentration of 0.1% by mass or less is disclosed. .

JP 2005-235509 A JP 2000-243486 A JP 2001-015190 A JP 2002-170608 A JP 2002-173702 A

As described above, conventionally, anisotropic conductive sheets having various configurations are known.
By the way, a circuit board to be connected / inspected is usually not flat but has a step or is bent. In particular, in order to connect an element such as a mobile phone to a small space, this step or bend tends to become larger.

  Therefore, the circuit connecting member has a constant electrical resistance value with respect to the stability (indentation resistance) of the electrical resistance value with respect to the sheet pressing amount (sheet displacement amount), that is, the load amount in the thickness direction of the sheet. Performance is required.

  However, the conventional circuit connecting member does not have sufficient indentation resistance. That is, an object of the present invention is to provide a circuit connecting member having sufficient indentation resistance.

The present inventors have intensively studied to solve the above problems. As a result, it has been found that the above problems can be solved by using conductive particles having a specific shape, and the present invention has been completed.
That is, the present invention and preferred embodiments thereof relate to the following [1] to [16].

  [1] A sheet-like circuit connecting member formed from a sheet forming material containing a polymer material and conductive particles, wherein the conductive particles have at least one flat portion. Connection member.

[2] The circuit connection member according to [1], wherein the conductive particles have at least two flat portions.
[3] The circuit connection member according to [2], wherein at least two flat portions of the conductive particles are present at positions parallel to each other.

[4] The circuit connection member according to any one of [1] to [3], wherein the conductive particles are conductive ferromagnetic particles.
[5] The conductive ferromagnetic particles are single metal particles, composite particles in which two or more metals are mixed, coated particles formed by coating the metal particles or composite particles with metal, organic or inorganic materials. [4] The circuit connection member according to [4], which is a coated particle formed by coating with a metal, or two or more kinds of mixed particles selected from the single metal particles, composite particles, and coated particles.

  [6] When the volume fraction of all components in the circuit connecting member is 100%, the content ratio (volume fraction) of the conductive particles is 3 to 50%. The circuit connection member as described in any one of Claims.

  [7] The sheet connection circuit member according to any one of [1] to [5], which is a sheet-like circuit connection member including a plurality of conductive portions containing the conductive particles and an insulating portion that insulates the conductive portions from each other. Circuit connection member.

[8] The circuit connection member according to [7], wherein the conductive part is a large number of conductive parts extending in a thickness direction, and is formed from an aggregate of the conductive particles and a polymer material.
[9] The circuit connection member according to [7] or [8], wherein the volume fraction of the conductive portion is 5 to 80% when the volume fraction of all components in the circuit connection member is 100%. .

[10] Conductive particles for circuit connection members, having at least one flat part.
[11] The conductive particle according to [10], which has at least two flat portions.

[12] The conductive particle according to [11], wherein at least two flat portions of the conductive particle are present at positions parallel to each other.
[13] The conductive particle according to any one of [10] to [12], which is a conductive ferromagnetic particle.

  [14] Single metal particles, composite particles in which two or more kinds of metals are mixed, coated particles formed by coating the metal particles or composite particles with metal, coated particles formed by coating an organic or inorganic material with metal Alternatively, the conductive particles according to [13], which are two or more kinds of mixed particles selected from the simple metal particles, composite particles, and coated particles.

[15] A method for producing conductive particles according to any one of [10] to [14], wherein the steps shown in the following (1), (2a) and (3) are sequentially performed. A method for producing conductive particles.
(1) A step of forming a resist pattern corresponding to the shape of the conductive particles on the substrate.
(2a) A step of depositing a conductive particle forming material between the resist patterns.
(3) A step of removing the resist pattern and the substrate.

[16] A method for producing conductive particles, which are coated particles obtained by coating the organic or inorganic material according to [14] with a metal, the following (1), (2b), (3) and (4) A process for producing conductive particles, wherein the steps shown in FIG.
(1) A step of forming a resist pattern corresponding to the shape of the conductive particles on the substrate.
(2b) A step of forming particles made of an organic or inorganic material between the resist patterns.
(3) A step of removing the resist pattern and the substrate.
(4) A step of coating a part or all of the surface of the obtained particles with a metal.

  According to the present invention, a circuit connecting member having sufficient indentation resistance is provided. Moreover, the electroconductive particle for circuit connection members which makes it possible to provide such a circuit connection member, and its manufacturing method are also provided.

FIG. 1 is a schematic diagram for explaining the indentation resistance of the circuit connection member of the present invention. FIG. 2 is a view showing a specific example of the unevenly distributed circuit connecting member of the present invention. FIG. 3 is a diagram for explaining the production process of the conductive particles of the example. FIG. 4 shows the evaluation results of the circuit connection members of the example and the comparative example.

  Hereinafter, after describing the conductive particles for circuit connection members and the manufacturing method thereof, which are the features of the present invention, details of the circuit connection members of the present invention (for example, distributed / unevenly distributed circuit connection members) will be described.

[Conductive particles for circuit connection members]
Hereinafter, the conductive particles for a circuit connection member of the present invention will be described with reference to the drawings.
The conductive particles for a circuit connecting member of the present invention have at least one flat portion.

  The effect of the present invention is presumed to be manifested for the following reason. When the circuit connecting member is pushed in the thickness direction, a force acts on the contacting conductive particles so as to move in a direction perpendicular to the pushing direction. Therefore, when using spherical or elliptical conductive particles as in the past, the contact between the conductive particles is not maintained by this force, so the electrical resistance value with respect to the load amount in the thickness direction of the circuit connecting member Variation will occur. However, since the conductive particles of the present invention have a flat portion, as shown in FIG. 1 (A), contact between the conductive particles is prevented against the movement of the conductive particles in the direction perpendicular to the pressing direction due to the pressing force. Can keep. Further, the contact between the conductive particles here is a surface contact, so that the contact property is good. For this reason, the electrical resistance value is constant with respect to the load amount in the thickness direction of the circuit connecting member, and a circuit connecting member having sufficient indentation resistance can be obtained.

In the present invention, the “flat portion” is substantially an area of 9 × 10 ⁻¹² m ² or more, preferably an area of 2.5 × 10 ⁻¹¹ m ² or more, more preferably an area of 1 × 10 ⁻¹⁰ m ² or more. A portion that is a substantially flat surface having no step or bend. The shape of the flat portion is not particularly limited, and examples thereof include a polygonal shape such as a circle, an ellipse, and a rectangle, and may include a gently curved surface or a fine uneven surface.

  The conductive particles preferably have at least two flat portions. Furthermore, it is more preferable that these flat portions exist at positions parallel to each other. Examples of the shape of the conductive particles in which at least two flat portions exist in parallel to each other include a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, an elliptical column shape, a polygonal column shape, a drum shape, and a drum shape. When conductive particles having at least two flat portions in parallel with each other are used in this way, the normal direction of the flat portion of the particles is substantially aligned with the thickness direction of the circuit connecting member due to magnetic field orientation or the like. The particles can be oriented (see FIG. 1B). In the case of conductive particles having two or more sets of flat portions present at positions parallel to each other such as cubic or rectangular parallelepiped conductive particles, the normal line of one set of flat portions existing at positions parallel to each other It is preferable to make the direction substantially coincide with the thickness direction of the circuit connecting member because the indentation resistance is considered to be further improved.

The particle diameter of the conductive particles is usually 2 to 200 μm, preferably 5 to 150 μm, more preferably 7 to 100 μm. For example, when the conductive particles have a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, an elliptical column shape, or a polygonal column shape, the bottom area is usually 9 × 10 ⁻¹² to 1 × 10 ⁻⁸ m ² , preferably 1 × 10 ⁻¹⁰ to 1 × 10 ⁻⁸ m ² , and the height (thickness) is usually 5 to 200 μm, preferably 10 to 100 μm.

  In the present invention, the particle diameter (length and thickness) of the conductive particles and the area of the flat portion are measured by a scanning electron microscope or a laser displacement meter. In the rectangular parallelepiped conductive particles, the smallest side among the three sides is defined as the thickness direction.

The conductive particles can be easily oriented or assembled in the thickness direction of the circuit connecting member by applying a magnetic field, and as a result, better indentation resistance can be obtained. Magnetic particles are preferred. In the present invention, “ferromagnetic” means a material having a magnetic susceptibility of 1 × 10 ⁶ cm ³ / g or more.

  The conductive particles do not need to be entirely formed of a conductive material, and at least the surface may be formed of a conductive material. The means for coating the surface of the particles with the conductive metal is not particularly limited, and examples thereof include electroplating or electroless plating.

  Conductive particles include single metal particles, composite particles in which two or more metals are mixed, coated particles formed by coating the metal particles or composite particles with metal, and organic or inorganic materials coated with metal. Or two or more kinds of mixed particles selected from the single metal particles, composite particles and coated particles.

  Examples of such conductive particles include (1) particles of metals that exhibit ferromagnetism such as nickel, iron, and cobalt, and particles of alloys containing these, and (2) inorganic particles such as ceramics and organic particles such as resins. Particles obtained by kneading the metal particles or alloy particles therein and having magnetism, (3) particles formed by coating these particles with gold, silver, copper, tin, palladium, rhodium, etc., and the like, and (4) Inorganic particles such as polymer particles, non-magnetic metal particles, or glass beads are particles obtained by plating a metal exhibiting ferromagnetism such as nickel, iron, cobalt, and the like.

  From the viewpoint of reducing the manufacturing cost, nickel, iron, or an alloy thereof is preferable. Further, in applications such as sockets and connectors that use electrical characteristics of low conduction resistance, particles whose surfaces are plated with gold are preferable.

[Method for producing conductive particles for circuit connecting member]
The 1st manufacturing method of the electroconductive particle for circuit connection members of this invention is a manufacturing method of the electroconductive particle which has the said flat part, Comprising: The process shown to following (1), (2a) and (3) It is characterized by performing sequentially. You may further perform the process shown to following (4) as needed.

(1) A step of forming a resist pattern corresponding to the shape of the conductive particles on the substrate.
(2a) A step of depositing a conductive particle forming material between the resist patterns.
(3) A step of removing the resist pattern and the substrate.
(4) A step of coating a part or all of the surface of the obtained particles with a metal.

<< Process (1) >>
In step (1), a resist pattern corresponding to the shape of the above-described conductive particles described above is formed on the substrate. Hereinafter, the substrate on which the resist pattern is formed is also referred to as a “patterning substrate”.

  The method for forming the resist pattern and the resist composition used are not particularly limited, and conventionally known methods and resist compositions can be employed. For example, the resist composition is described in JP-A-8-301911, JP-A-2005-181976, and JP-A-2005-189810 in view of damage to the resist pattern during electroforming. Resist compositions are preferred, and the conditions described in these publications can be adopted as the resist pattern formation conditions.

  Usually, a resist composition is applied onto a substrate to form a coating film, and an exposure process and a development process are performed to form a resist pattern corresponding to the shape of the conductive particles. The following description is one specific example, but the formation conditions of the resist pattern are not limited to these.

  Coating film formation: A resist composition is applied on a substrate and dried by heating to remove the solvent, thereby forming a desired coating film. As the substrate, a conductive substrate (eg, SUS plate, copper foil plate) is usually used. Examples of the coating method on the substrate include a spin coating method, a roll coating method, a screen printing method, and an applicator method. The drying condition of the coating film varies depending on the type of each component in the resist composition, the blending ratio, the thickness of the coating film, etc., but is usually 40 to 160 ° C., preferably 50 to 150 ° C., for about 5 to 60 minutes. is there.

Exposure process: The obtained coating film is irradiated with actinic rays through a photomask having a pattern corresponding to the shape of the conductive particles described in detail. Here, active light means ultraviolet light, visible light, and the like, and examples of the light source include known light sources such as a carbon arc lamp, a mercury vapor arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, and a xenon lamp. The irradiation amount of actinic rays varies depending on the type of each component in the resist composition, the blending ratio, the thickness of the coating film, and the like, but is usually 100 to 1500 mJ / cm ² when a (super) high pressure mercury lamp is used.

Development processing: The resist film is formed by selectively removing the coating film (negative type) in the unexposed area or the coating film (positive type) in the exposed area using a developer. As the developer, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanol Amine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [4.3.0] An aqueous solution of an alkali such as -5-nonane can be used. Further, an aqueous solution obtained by adding an appropriate amount of a water-soluble organic solvent such as methanol or ethanol or a surfactant to the alkaline aqueous solution can also be used as a developer. In addition, after the development process with an alkaline aqueous solution is performed, a washing process is usually performed.
The thickness of the resist pattern is usually 5 to 200 μm, preferably 10 to 100 μm, more preferably 20 to 80 μm, corresponding to the thickness of the conductive particles.

<< Step (2a) >>
In the step (2a), a conductive particle forming material is deposited between the resist patterns. Here, the resist pattern serves as a mold. In order to deposit the conductive particle forming material, for example, an electroplating method or the like can be employed. Specifically, the patterning substrate is dipped in various plating solutions for electroplating, and plating is performed by setting the current value and energizing time so as to obtain a desired plating thickness, thereby forming an electroformed product. Examples of the various plating solutions include nickel plating solutions, cobalt plating solutions, iron plating solutions, and alloy plating solutions containing those metal ions.

<< Step (3) >>
In step (3), the resist pattern and the substrate are removed. In order to peel the resist pattern and the substrate from the conductive particles formed between the patterns, for example, the patterning substrate may be immersed in a stripping solution being stirred at 50 to 80 ° C. for 5 to 30 minutes. Examples of the stripping solution used here include an aqueous solution of a quaternary ammonium salt, a mixed solution of a quaternary ammonium salt, dimethyl sulfoxide and water, and an aqueous sodium hydroxide solution.

<< Step (4) >>
In step (4) performed as necessary, a part or all of the surface of the obtained particles is coated with a metal. The means for coating the surface of the particles with the conductive metal is not particularly limited, and examples thereof include electroplating or electroless plating. Examples of the various plating solutions include a gold plating solution, a silver plating solution, a copper plating solution, a nickel plating solution, and a solder plating solution.

As described above, the conductive particles of the present invention can be produced.
A second method for producing conductive particles for a circuit connecting member of the present invention is a method for producing conductive particles which are coated particles having the above-mentioned flat portion and coated with an organic or inorganic material with a metal. Then, the following steps (1), (2b), (3) and (4) are sequentially performed.

(1) A step of forming a resist pattern corresponding to the shape of the conductive particles on the substrate.
(2b) A step of forming particles made of an organic or inorganic material between the resist patterns.
(3) A step of removing the resist pattern and the substrate.
(4) A step of coating a part or all of the surface of the obtained particles with a metal.

<< Process (1) >>
Step (1) is the same as step (1) described in detail in the first production method.

<< Step (2b) >>
In the step (2b), particles made of an organic or inorganic material are formed between the resist patterns. As the formation method, for example, a composition such as an organic material (such as a thermosetting resin), an inorganic material (such as a ceramic material or polysiloxane), or a mixture of an organic material and an inorganic material is resisted by screen printing or intaglio printing. A method of curing after embedding between the patterns can be mentioned. In the case where a resin paste, ceramic paste, or the like mixed with magnetic particles (ferrite, ferromagnetic metal powder, etc.) is used as the composition, the following plating step for imparting magnetism after the curing treatment can be omitted.

<< Step (3) >>
Step (3) is the same as step (3) described in detail in the first production method.

<< Step (4) >>
In the step (4), a part or all of the surface of the obtained particle is coated with a metal. The means for coating the surface of the particles with the conductive metal is not particularly limited, and examples thereof include electroplating or electroless plating. Examples of the various plating solutions include nickel plating solutions, cobalt plating solutions, iron plating solutions, and alloy plating solutions containing those metal ions.
As described above, the conductive particles of the present invention can be produced.

[Circuit connection member]
The circuit connecting member of the present invention is a sheet-like circuit connecting member formed from a sheet forming material containing a polymer material and conductive particles, and the conductive particles have at least one flat portion. It is characterized by. The conductive particles are the above-described conductive particles of the present invention.

The above circuit connection member includes a "dispersed circuit connection member" in which conductive particles are uniformly dispersed in the surface direction of the circuit connection member, a large number of conductive parts containing conductive particles, and an insulating part that insulates them from each other Any of the sheet-like “unevenly-distributed circuit connecting member” composed of The distributed circuit connection member of the present invention exhibits conductivity only in the thickness direction when pressed in the thickness direction. The unevenly distributed circuit connection member of the present invention may be conductive only in the thickness direction, or may be conductive only in the thickness direction when pressed in the thickness direction.
The circuit connecting member of the present invention is in the form of a sheet, and the thickness of the sheet is not particularly limited and can be appropriately determined according to the purpose, and is usually 0.1 to 10 mm.

《Distributed circuit connection member》
In the distributed circuit connection member of the present invention, it is preferable that the conductive particles are uniformly dispersed in the surface direction of the circuit connection member and are aligned in the thickness direction. When using a conductive ferromagnetic particle as the conductive particle and manufacturing a circuit connecting member by magnetic field orientation, the conductive ferromagnetic particles can be aligned in the thickness direction by the magnetic field orientation, and thus the obtained circuit connecting member Becomes highly anisotropic. In particular, it is preferable that the conductive particles are arranged so that the normal direction of the flat portions present at the parallel positions of the conductive particles substantially coincides with the thickness direction of the circuit connecting member. In the case of conductive particles having two or more sets of flat portions present at positions parallel to each other such as cubic or rectangular parallelepiped conductive particles, the normal line of one set of flat portions existing at positions parallel to each other It is preferable to make the direction substantially coincide with the thickness direction of the circuit connecting member because the indentation resistance is considered to be further improved.

  When the volume fraction of all components in the distributed circuit connecting member of the present invention is 100%, the content ratio (volume fraction) of the conductive particles is usually 3 to 50%, preferably 5 to 25%. More preferably, it is 7 to 23%. When this content ratio is less than the above range, a circuit connecting member having a sufficiently small electric resistance value may not be obtained. On the other hand, when the content ratio exceeds the above range, the obtained circuit connection member tends to be fragile, and the elasticity necessary for the circuit connection member may not be obtained. Furthermore, electrical insulation between the connection terminal and other connection terminals may not be ensured.

The distributed circuit connection member of the present invention can be manufactured, for example, by the following method.
First, a sheet forming material containing a polymer material and conductive particles is prepared. Here, the defoaming process by pressure reduction can be performed with respect to a sheet forming material as needed. In the sheet forming material, the content ratio (volume fraction) of the conductive particles is usually 5 to 50%, preferably 5 to 25%, more preferably 7 to 23%.

  Next, the sheet forming material is applied onto a conventionally known substrate film (eg, polytetrafluoroethylene (PTFE) film) to form a sheet forming material layer, and a coated substrate comprising the sheet forming material layer and the substrate film. Manufacturing.

  Next, for example, an electromagnet or a permanent magnet is disposed on the upper and lower surfaces of the coated substrate, and a parallel magnetic field is applied in the thickness direction of the sheet forming material layer. By this magnetic field orientation, the conductive particles dispersed in the sheet forming material layer are aligned in the thickness direction while maintaining a state of being uniformly dispersed in the surface direction. The intensity of the parallel magnetic field applied to the sheet forming material layer is preferably 0.02 to 1.5 T (Tesla) on average. Note that the step of applying the parallel magnetic field can be omitted.

  Here, by curing the sheet forming material layer, the conductive particles are uniformly dispersed in the surface direction in the cured layer formed from the polymer material (preferably the insulating polymer material), and the thickness is increased. The distributed circuit connecting member of the present invention contained in an aligned state in the direction is obtained.

  The curing process of the sheet forming material layer can be performed with the parallel magnetic field applied, but can also be performed after the parallel magnetic field is stopped. Alternatively, the parallel magnetic field may be applied again after the action of the parallel magnetic field is stopped halfway and the direction of action is reversed.

  The curing treatment of the sheet forming material layer is appropriately selected depending on the type of polymer material, but is usually performed by heat treatment. Specific heating temperature and heating time are appropriately set in consideration of the type of polymer material, the time required for orientation of the conductive particles, and the like.

<< Unevenly distributed circuit connection member >>
In the unevenly distributed circuit connecting member of the present invention, the conductive portion is formed according to the electrode pattern of the circuit board or the like and the opposite pattern, so that the electrodes to be connected are arranged at a smaller pitch than the distributed circuit connecting member. This is advantageous in that the electrical connection between the electrodes can be achieved with high reliability even for a circuit device or the like. In particular, the unevenly distributed circuit connecting member formed so that the conductive portion protrudes from the insulating portion is more advantageous in that the contact with the electrode to be inspected is reliably performed.

  FIG. 2 shows a schematic view of a part of a cross section perpendicular to the upper surface 5 and the lower surface 6 of the circuit connection member 1 which is a specific example of the unevenly distributed circuit connection member of the present invention (the shape of the conductive particles is spherical for convenience). Although shown, it is actually a particle having the flat part). Hereinafter, the basic structure of the unevenly distributed circuit connection member of the present invention will be described by taking the circuit connection member 1 as an example.

  The circuit connection member 1 includes a large number of conductive parts 2 containing conductive particles 2 and an insulating part 3 that insulates them from each other. For example, when the volume fraction of all components in the circuit connecting member 1 is 100%, the volume fraction of the conductive portion 2 is usually 5 to 80%, preferably 10 to 70%, more preferably 20 to 60%.

  The conductive portion 2 is formed from the upper surface 5 to the lower surface 6 of the circuit connection member 1 and has a function of ensuring conductivity in the thickness direction of the circuit connection member 1. A large number of conductive portions 2 are formed to such an extent that the conductivity in the thickness direction of the circuit connecting member 1 can be secured. That is, the conductive portion 2 is preferably a large number of conductive portions extending in the thickness direction, and is preferably formed from an aggregate of conductive particles 4 and a polymer material.

  The conductive particles 4 are preferably oriented in a state where they are aligned in the thickness direction. In particular, it is preferable that the conductive particles are arranged so that the normal direction of the flat portions present at the parallel positions of the conductive particles substantially coincides with the thickness direction of the circuit connecting member. The conductive particles 4 are arranged in the thickness direction of the circuit connecting member 1 from the upper surface 5 to the lower surface 6 while being in contact with each other or in contact with each other when being pressed to form the conductive portion 2. That is, the conductive portion 2 may be conductive only in the thickness direction, or may be a pressure conductive portion in which the resistance portion decreases and the conductive portion 2 is formed when pressed and compressed in the thickness direction. .

The insulating portion 3 is formed of a polymer material so as to surround the conductive portion 2 in the surface direction, and has a function of insulating a large number of the conductive portions 2 from each other and ensuring insulation in the surface direction of the circuit connecting member 1.
There is no restriction | limiting in particular in the shape of the cross section parallel to the surface direction of a circuit connection member of an electroconductive part, Circular shape, elliptical shape, linear shape, and other arbitrary shapes can be taken. The shape and size of the cross section of the conductive portion may be the same at any position in the thickness direction of the circuit connecting member, or may be different depending on the position in the thickness direction. The diameter of the conductive part is usually 0.02 to 1 mm, preferably 0.05 to 0.5 mm. Moreover, as long as the electroconductivity part of the thickness direction of a circuit connection member is ensured, the electroconductive part may be formed in parallel with the thickness direction of a circuit connection member, and does not need to be formed in parallel.

  It is preferable that the aggregate density of the conductive particles in the conductive portion viewed from the surface side of the circuit connection member is uniform. When the assembly density is uniform, it becomes easy to reduce the conduction resistance to such an extent that the circuit connecting member can be used for mounting an electronic circuit such as a socket or a connector.

  The unevenly distributed circuit connection member of the present invention may have a flat surface portion and a protrusion portion including a conductive portion protruding from the flat surface portion on at least one of the upper surface and the lower surface. The shape of the protrusion is not particularly limited, and examples thereof include a disk-shaped protrusion. When the circuit connection member has such a protrusion, there is an advantage that the load applied to the connection terminal during pressurization can be reduced.

The uneven distribution type circuit connecting member of the present invention can be manufactured, for example, by the following method.
First, a sheet forming material containing a polymer material and conductive particles is prepared. Here, the defoaming process by pressure reduction can be performed with respect to a sheet forming material as needed. In the sheet forming material, the content ratio (volume fraction) of the conductive particles is determined in consideration of the content ratio of the conductive particles in the conductive portion to be formed, and is usually 5 to 40%, preferably 8 ˜33%, more preferably 10-30%.

  Next, (1) the sheet forming material is injected into a mold including an electromagnet and a magnetic pole plate to form a sheet forming material layer, and (2) a magnetic field having an intensity distribution with respect to the sheet forming material layer. By acting in the thickness direction of the sheet-forming material layer, the conductive particles in the sheet-forming material layer are gathered in a portion to be a conductive portion, (3) by curing the sheet-forming material layer in that state, An unevenly distributed circuit of the present invention comprising a large number of conductive portions in which conductive particles are densely packed in a hardened layer formed of a polymer material, and an insulating portion formed of a polymer material that insulates them from each other A connecting member is obtained.

  The curing process of the sheet forming material layer can be performed with the parallel magnetic field applied, but can also be performed after the parallel magnetic field is stopped. Alternatively, the parallel magnetic field may be applied again after the action of the parallel magnetic field is stopped halfway and the direction of action is reversed.

  The curing treatment of the sheet forming material layer is appropriately selected depending on the type of polymer material, but is usually performed by heat treatment. Specific heating temperature and heating time are appropriately set in consideration of the type of polymer material, the time required for orientation of the conductive particles, and the like.

《Polymer material》
The polymer material used in the circuit connection member of the present invention is not particularly limited as long as the effects of the present invention are not impaired, but is preferably an insulating polymer material. Insulating polymer materials include silicone rubber, ethylene propylene rubber, urethane rubber, fluorine rubber, polyester rubber, styrene butadiene rubber, styrene butadiene block copolymer rubber, styrene isopropylene block copolymer rubber, Examples include soft epoxy resins.

  As the insulating polymer material, a material that is liquid at the temperature at the time of sheet manufacture or has fluidity and is then cured is preferable. When the insulating polymer material has such properties, the conductive ferromagnetic particles can be oriented or assembled by applying a magnetic field during sheet production, and then the insulating polymer material is cured to be conductive. Ferromagnetic particles can be fixed.

  For example, thermosetting silicone rubber is preferable because it is in a liquid state at normal temperature and is cured by heating to become a solid rubber. Also, for example, soft liquid epoxy resins, thermoplastic elastomers, thermoplastic soft resins, etc. are preferable because they are fluid at the time of sheet production to be described later and become solid after sheet production even if they are solid at room temperature.

  Further, as the insulating polymer material, those having a crosslinked structure are preferable in terms of heat resistance and durability. Examples of the material having such a crosslinked structure include silicone rubber, ethylene propylene rubber, urethane rubber, fluorine rubber, polyester rubber, styrene butadiene rubber, styrene butadiene block copolymer rubber, and styrene isopropylene block copolymer. Examples include polymer rubber and soft epoxy resin.

  Insulating polymer materials that are solid and have rubber elasticity absorb irregularities on their surfaces when connecting circuit connection members to electrical circuit components, electrical circuit boards, etc. It is preferable in that it is advantageous for obtaining a mechanical contact. Depending on the use of the sheet, it may be of low elasticity.

  In addition, when it is required to adhere or adhere the circuit connecting member to a substrate or the like, the insulating polymer material is preferably an insulating polymer material having adhesiveness or tackiness. Examples of such an insulating polymer material having adhesiveness or tackiness include epoxy resins and melamine resins.

(1) Production of conductive particles [Example 1] Production of conductive particles (see FIG. 3)
The resist composition was applied on a SUS plate using a spin coater, and then heat-treated at 100 ° C. for 5 minutes on a hot plate to form a coating film having a thickness of 50 μm. The obtained coating film was exposed to ultraviolet rays of 600 mJ / cm ² using a super high pressure mercury lamp (USH-1000KS manufactured by USHIO INC.) Through a pattern mask of 100 μm × 50 μm. The exposed coating film was developed with a 2.38 wt% aqueous solution of tetramethylammonium hydroxide. Thereafter, it was washed with running water with deionized water and spin-dried to form a resist pattern having a hole pattern of 100 μm in length, 50 μm in width, and 50 μm in height. A substrate having this resist pattern is referred to as a “patterning substrate”.

  Nickel plating was performed on the patterning substrate using an electrolytic nickel bath (nickel sulfamate bath). Thereafter, THB-S2 (manufactured by JSR) was used as a stripping solution, and the resist pattern and the SUS plate were stripped by immersing the patterning substrate while stirring at 50 ° C. for 10 minutes to obtain a nickel electroformed product. When this nickel electroformed product was observed with a scanning electron microscope (SEM), it was a rectangular parallelepiped having a length of 100 μm, a width of 50 μm, and a height of 50 μm.

By the electroless plating method, gold plating was performed on the surface of the nickel electroformed product under the condition that the thickness of the gold plating was approximately 60 to 100 nm to obtain conductive particles. When the conductive particles were observed with a scanning electron microscope (SEM), they were rectangular parallelepipeds having a length of 100 μm, a width of 50 μm, and a height of 50 μm. It was 55 * 10 < ⁹ > cm < ³ > / g when the magnetic susceptibility was measured with the magnetic susceptibility measuring apparatus.

In addition, as the resist composition, an alkali-soluble resin (methacrylic acid / p-isopropenylphenol / isobornyl acrylate / n-butyl acrylate / tricyclo (5.2.1.0 ^2,6 ) decanyl methacrylate = 10 / 15/40/5/15 (parts by weight of copolymer) 100 parts by weight, as ethylenically unsaturated compound, trade name “Aronix M8100” (manufactured by Toagosei Co., Ltd.), 60 parts by weight, trade name “ 10 parts by weight of Aronix M320 "(manufactured by Toagosei Co., Ltd.) and 2,2'-bis (2-chlorophenyl) -4,5,4 ', 5'-tetraphenyl-1,2 as a radical polymerization initiator 4 parts by weight of '-biimidazole, 10 parts by weight of 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, 4,4'-bis (die A composition containing 0.2 part by weight of (tilamino) benzophenone, 0.3 part by weight of a trade name “FTX-218” (manufactured by Neos Co., Ltd.) and 150 parts by weight of ethyl lactate as a surfactant was used.

(2) Manufacture of circuit connection member [Example 2] Manufacture of circuit connection member The conductive particles obtained in Example 1 are added to the addition-type liquid silicone rubber so that the volume fraction of the conductive particles is 12%. After being added to and mixed, a sheet forming material was prepared by performing a defoaming treatment under reduced pressure. This sheet forming material was applied on a PTFE film (trademark) by a screen printing method to form a coated substrate. The obtained coated substrate was placed in a parallel magnetic field (0.5 to 1 Tesla) while being heated to 100 ° C., and an external magnetic field was applied for 30 minutes. After peeling off the PTFE film, a dispersion type circuit connecting member having a thickness of 400 μm was manufactured by performing a heat treatment at 200 ° C. for 4 hours.

  The addition-type liquid silicone rubber is a two-component type in which the viscosity of the liquid A is 250 Pa · s and the viscosity of the liquid B is 250 Pa · s, and the cured product has a permanent compression strain of 5 at 150 ° C. %, The durometer A hardness of the cured product was 35, and the tear strength of the cured product was 25 kN / m.

[Comparative Example 1]
A circuit connecting member was produced in the same manner as in Example 2 except that spherical nickel particles having a diameter of 50 μm (gold thickness = 60 to 100 nm) coated with gold were used as the conductive particles.

(3) Evaluation of circuit connection member (indentation resistance)
A circuit connection member was placed on the gold-plated plate, and a probe electrode (circular shape with a diameter of 300 μm) was placed thereon. While pushing the probe electrode, the resistance value (Ω) of the current flowing between the gold-plated plate and the probe electrode was measured. The results are shown in Table 1 and FIG.

上記結果から明らかなように、実施例２の回路接続部材は、シートの厚み方向に係る負荷量に対して電気抵抗値が一定であった。これに対して、比較例１の回路接続部材は、シートの厚み方向に係る負荷量に対して電気抵抗値にバラツキが生じた。

As is clear from the above results, the circuit connection member of Example 2 had a constant electrical resistance value with respect to the load amount in the thickness direction of the sheet. On the other hand, the circuit connection member of Comparative Example 1 had variations in the electric resistance value with respect to the load amount in the thickness direction of the sheet.

DESCRIPTION OF SYMBOLS 1 ... Circuit connection member 2 ... Conductive part 3 ... Insulating part 4 ... Conductive particle 5 ... Upper surface 6 of a circuit connection member ... Lower surface of a circuit connection member

Claims (16)

  A circuit connection member, which is a sheet-like circuit connection member formed from a sheet forming material containing a polymer material and conductive particles, wherein the conductive particles have at least one flat portion.   The circuit connection member according to claim 1, wherein the conductive particles have at least two flat portions.   The circuit connection member according to claim 2, wherein at least two flat portions of the conductive particles are present at positions parallel to each other.   The circuit connection member according to claim 1, wherein the conductive particles are conductive ferromagnetic particles.   The conductive ferromagnetic particles are single metal particles, composite particles obtained by mixing two or more metals, coated particles obtained by coating the metal particles or composite particles with metal, and organic or inorganic materials are coated with metal. The circuit connection member according to claim 4, wherein the circuit connection member is a coated particle, or two or more kinds of mixed particles selected from the single metal particles, composite particles, and coated particles.   The content ratio (volume fraction) of the conductive particles is 3 to 50% when the volume fraction of all components in the circuit connecting member is 100%. The circuit connection member as described.   The circuit connection member according to any one of claims 1 to 5, wherein the circuit connection member is a sheet-like circuit connection member including a plurality of conductive portions containing the conductive particles and an insulating portion that insulates the conductive portions.   The circuit connection member according to claim 7, wherein the conductive portion is a large number of conductive portions extending in a thickness direction, and is formed from an aggregate of the conductive particles and a polymer material.   The circuit connection member according to claim 7 or 8, wherein the volume fraction of the conductive portion is 5 to 80% when the volume fraction of all components in the circuit connection member is 100%.   Conductive particles for circuit connection members, characterized by having at least one flat part.   The electroconductive particle of Claim 10 which has an at least 2 flat part.   The conductive particle according to claim 11, wherein at least two flat portions of the conductive particle are present at positions parallel to each other.   It is an electroconductive ferromagnetic particle, The electroconductive particle as described in any one of Claims 10-12.   A single metal particle, a composite particle in which two or more metals are mixed, a coated particle obtained by coating the metal particle or the composite particle with a metal, a coated particle obtained by coating an organic or inorganic material with a metal, or the above The conductive particles according to claim 13, which are two or more kinds of mixed particles selected from simple metal particles, composite particles, and coated particles. It is a manufacturing method of the electroconductive particle as described in any one of Claims 10-14, Comprising: The process shown to the following (1), (2a) and (3) is performed sequentially, Conductive particle | grains characterized by the above-mentioned. Production method.
(1) A step of forming a resist pattern corresponding to the shape of the conductive particles on the substrate.
(2a) A step of depositing a conductive particle forming material between the resist patterns.
(3) A step of removing the resist pattern and the substrate. It is a manufacturing method of the electroconductive particle which is a covering particle formed by coat | covering the organic or inorganic material of Claim 14 with a metal, Comprising: The process shown to following (1), (2b), (3) and (4) A method for producing conductive particles, which is performed sequentially.
(1) A step of forming a resist pattern corresponding to the shape of the conductive particles on the substrate.
(2b) A step of forming particles made of an organic or inorganic material between the resist patterns.
(3) A step of removing the resist pattern and the substrate.
(4) A step of coating a part or all of the surface of the obtained particles with a metal.

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