KR101505214B1 - Electrical connection body and method for fabricating the same - Google Patents

Abstract

Provided is an electrical connecting body capable of uniformly crushing the conductive particles contained in the anisotropic conductive film even when the particle diameter is small, and obtaining good conduction characteristics. The electrical connecting body is constituted such that a semiconductor element 1 as a first electronic member and a wiring substrate 3 as a second electronic member are electrically connected via an anisotropic conductive film 5. Bumps (protruding electrodes) 2 are formed on one of the electronic members (here, the semiconductor element 1), and the tops of the bumps 2 are flat surfaces having a surface roughness Ra of 0.05 m or less. The average particle diameter of the conductive particles 6 contained in the anisotropic conductive film 5 is 4 占 퐉 or less.

A semiconductor element, a wiring board, an anisotropic conductive film,

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrical connecting body,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical connection body in which electronic components such as semiconductor elements and electronic boards are electrically connected to each other. More particularly, the present invention relates to an electrical connection body in which electrical connection is made using protruding electrodes (bumps) and anisotropic conductive films.

BACKGROUND ART [0002] Conventionally, for example, when an electronic member such as a semiconductor element is mounted on a wiring board, it is widely practiced to electrically connect the terminal electrode of the semiconductor element and the electrode of the wiring substrate by wire bonding. However, in this kind of wire bonding connection, it is necessary to connect the electrodes with each other through a bonding wire, so that the connection process is troublesome, and it is difficult to cope with miniaturization of the terminal electrode due to high-density mounting, There is a need for improvement.

In such a situation, a flip chip mounting method in which a semiconductor element is mounted on a wiring board in a so-called face-down state has been proposed. In this flip chip mounting method, a protruding electrode called a bump is formed on either one of a terminal electrode of a semiconductor element or an electrode of a wiring board, and the protruding electrode is disposed so as to face the other electrode, Method. The protruding electrodes are formed by plating Au, Cu, or solder, and the height thereof is about several 탆 to several tens of 탆.

In such a flip chip mounting method, an anisotropic conductive film is used for the purpose of improving connection reliability and the like. The anisotropic conductive film is formed by dispersing conductive particles in an insulating resin functioning as an adhesive. When the conductive particles are sandwiched between the protruding electrodes and the opposed electrodes and heated and pressed, the conductive particles are pressed and broken between the electrodes. In the portion where the projection electrode is not present, the conductive particles remain dispersed in the insulating resin, and the electrically insulated state is maintained. Therefore, electrical conduction can be achieved only at the portion where the projection electrode is present.

According to the flip chip mounting method using the anisotropic conductive film, as described above, a plurality of electrodes can be electrically connected together at one time, and there is no need to connect the electrodes with each other by bonding wires like wire bonding, It is relatively easy to cope with miniaturization of the terminal electrode and narrow pitching.

In the flip chip mounting method using such an anisotropic conductive film, in order to secure the reliability of the electrical connection, it is necessary to increase the ability to capture the conductive particles on the protruding electrodes, and studies have been made in various respects. For example, when the heights of the protruding electrodes are not uniform, a problem arises in connection, so that a technique of uniformizing the height of the protruding electrodes has been proposed (see, for example, Patent Documents 1 to 6).

Specifically, Patent Document 1 discloses a method of mounting a semiconductor element having an electrode portion on a substrate having an electrode pattern. Particularly, in this mounting method, a conductive protruding portion protruding from the surface of the semiconductor element is formed in the electrode portion of the semiconductor element, the protruding portion is once pushed into the surface of the rigid body, the adhesive resin is applied to at least one of the substrate or the semiconductor element The semiconductor element and the substrate are pressed and bonded to each other so that the projecting portion and the electrode pattern are in contact with each other, and then the resin for bonding is cured.

Patent Document 2 discloses a method of forming a bump used for bonding with an electrode of a semiconductor element on a plurality of electric paths formed on a surface of a substrate, A bump forming method is disclosed.

In Patent Document 3, at least a bump forming surface of a ceramic circuit board having a through hole filled with a conductor therein is polished, and a piece of metal is soldered on the through hole conductor exposed on the surface of the bump forming substrate. A manufacturing method is disclosed.

Patent Document 4 discloses a lead surface having a structure in which a silver plating layer is formed on a lower layer and a nickel plating layer is formed on the upper layer and a gold plating layer is formed on the upper layer, A protruding electrode in a columnar shape is formed by gold plating on a portion of the semiconductor device facing the electrode pad and the protruding electrode is pressed by the flat plate from the upward direction of the semiconductor device mounting substrate, And the surface of the plurality of protruding electrodes, which are the contact surfaces of the protruding electrodes, are matched in the same plane.

Patent Document 5 discloses a solder bump electrode in which the electrical property is inspected by contacting the solder bump electrode to reduce solder failure by reducing the height of the solder bump electrode to reduce the electrical connection resistance and improve the connection strength Thereafter, at least a top portion of the solder bump electrode is polished.

Patent Document 6 discloses a technique in which, with the aim of efficiently matching the bump height, the image pickup means focuses on the top of the bump, and the position of the cutting means at that time is set as the origin, And driving the means to cut the bumps.

In addition to the techniques described in Patent Documents 1 to 6, attempts have also been made to form protrusions and protrusions on protruding electrodes in order to enhance the ability to capture conductive particles between protruding electrodes and connection terminals (see, for example, Patent Documents 7 to 6 10).

For example, Patent Document 7 discloses a liquid crystal display device in which an electrode of a liquid crystal cell is connected to an electrode of a flexible substrate, and the electrode of the flexible substrate has a roughened surface .

In Patent Document 8, a semiconductor device (IC substrate) is provided face down on a flat base having abrasive sheets having abrasive grains so that the bumps come into contact with the polishing sheet, and the semiconductor device is pressed Discloses that ultrasonic vibration is applied to a flat base in a plane perpendicular to the direction of the bump to form an uneven surface on the front end face of the bump.

Patent Document 9 discloses a method of manufacturing a semiconductor device, which comprises a step of forming a gold bump on an electrode of a semiconductor device, a step of attaching an anisotropic conductive film on a circuit board, Forming a concave-convex portion on the end face of the gold bump by pressing the formed pressing substrate against the front end face of the gold bump of the semiconductor device; and aligning the gold bump and the electrode of the circuit board, And a step of pressing and heating the circuit board with the film attached thereto.

Patent Document 10 discloses a method in which a plurality of convex portions of a horn or trapezoidal shape made of a passivation film are previously formed on the wiring electrodes at the time of forming the bump electrodes and in this state, To form a gold electrode, thereby forming a bump electrode. As a result, a concavo-convex portion is formed on the electrode surface of the bump electrode corresponding to the concavo-convex portion formed on the wiring electrode.

Patent Document 1: JP-A-1-278034

Patent Document 2: JP-A-1-295433

Patent Document 3: JP-A-4-33395

Patent Document 4: JP-A-5-291262

Patent Document 5: Japanese Patent Application Laid-Open No. 2000-114313

Patent Document 6: JP-A-2006-324397

Patent Document 7: Japanese Utility Model Publication No. 63-174328

Patent Document 8: JP-A-6-283537

Patent Document 9: JP-A-11-16946

Patent Document 10: Japanese Laid-Open Patent Publication No. 2004-14778

DISCLOSURE OF INVENTION

However, in the anisotropic conductive film used for the flip chip mounting described above, the particle diameter of the conductive particles is usually in the range of 5 탆 to 10 탆. However, in order to meet the request of the recent fine pitch, Or to reduce the particle diameter of the conductive particles. For example, when the ratio of the conductive particles is large and the particle diameter of the conductive particles is large, the conductive particles are clogged between the protruding electrodes in the flip chip mounting with a fine pitch, thereby causing a short circuit.

In this case, decreasing the proportion of the conductive particles is directly related to the trapping property of the conductive particles, so it is appropriate to reduce the particle diameter of the conductive particles. When the particle diameter of the conductive particles is reduced, the conductive particles in the gap between the projection electrodes are dispersed in the insulating resin (adhesive), and the problem of shorting due to contact of the conductive particles with each other between the projection electrodes is avoided.

However, when the particle diameter of the conductive particles is reduced, there arises a problem that the conductive particles are not uniformly crushed by the height deviation of the projection electrodes, the mounting accuracy, and the like, and the phenomenon that the conductive resistance becomes unstable easily occurs. The height of each protruding electrode has a deviation of about 2 占 퐉 (the surface roughness Ra of the conventional protruding electrode is about 0.3 占 퐉). For example, when the average particle diameter of the conductive particles becomes 4 占 퐉 or less, It is difficult to raise.

Considering such a small-sized curing of the conductive particles, it is not possible to cope with the technique of making the height of the protruding electrodes uniform, such as the technique described in the above-described Patent Documents 1 to 6. In the techniques described in Patent Documents 1 to 6, although the height deviation between the protruding electrodes can be made small, the height deviation caused by the surface roughness of the protruding electrode top portion (front end flat portion) can not be eliminated, There is a deviation according to the surface roughness at the top of the electrode. Therefore, if the particle diameter of the conductive particles is reduced, the problem that the conductive particles on the protruded electrodes do not collapse uniformly remains unresolvable.

On the other hand, in the technique of forming the projections and depressions on the projection electrodes in order to enhance the trapping property of the conductive particles as in the above-described technologies described in the above-described Patent Documents 7 to 10, the surface roughness of the projection electrodes is increased. The trapped conductive particles can not be uniformly crushed because they enter into the concave and convex portions, and it is difficult to cope with the hardening of the conductive particles.

When mounting a semiconductor element or the like, annealing is generally performed for the purpose of adjusting the hardness of the protruding electrode to be uniform. However, even if the projecting electrode can reduce the surface roughness by performing a treatment such as cutting, the surface roughness of the projecting electrode is significantly increased by performing the annealing treatment.

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and it is an object of the present invention to provide a method of manufacturing an anisotropic conductive film by which even when the particle diameter of the conductive particles contained in the anisotropic conductive film is small, It is another object of the present invention to provide an electrical connecting body and a manufacturing method thereof.

The inventors of the present invention have conducted intensive studies over a long period of time in order to attain the above-mentioned object. As a result, there is a case in which irregularities are formed on the surface of the protruding electrode, but there is a case where the trapping property of the conductive particles is improved. Rather, the irregularities do not transfer sufficient pressure to the conductive particles in the portion located around the protruding electrode, On the other hand, the surface of the protruding electrode is made particularly smooth so that when the particle diameter of the conductive particles is small, the proportion of the conductive particles effectively acting by crushing increases, I came to find out that there is almost no problem.

The present invention has been completed on the basis of such findings. That is, the electrical connecting body according to the present invention for achieving the above-mentioned object is an electrical connecting body in which a first electronic member and a second electronic member are electrically connected via an anisotropic conductive film, And the top of the protruding electrode is a flat surface having a surface roughness Ra of 0.05 m or less after the annealing treatment.

The method for manufacturing an electrical contact according to the present invention for achieving the above object is a method for manufacturing an electrical connecting body according to any one of the first to fifth aspects of the present invention, wherein a top surface having a surface roughness Ra of 0.05 m or less Forming a protruding electrode on the protruded electrode; forming an anisotropic conductive film between the first electronic member and the secondelectronic member; pressing the conductive particles of the anisotropic conductive film opposed to the protruded electrode by pressing; And a step of electrically connecting the first electronic member and the second electronic member.

When an anisotropic conductive film in which conductive particles with small particle diameters are dispersed is used, an anisotropic conductive film is sandwiched between the first and second electromagnetic members when the surface roughness Ra of the protruding electrodes is large and irregularities are formed on the surface, When the anisotropic conductive film is pressed between the protruding electrode and the opposed electrode, pressure is not sufficiently transmitted to the conductive particles, for example, the concave portion of the surface of the protruding electrode. If the conductive particles are not crushed sufficiently, the electrical contact area or the like is insufficient and it is difficult to secure conduction reliability.

On the contrary, in the present invention, the surface roughness Ra of the protruding electrode is 0.05 m or less, which is a very smooth state. Particularly, in the present invention, the surface roughness Ra becomes 0.05 m or less even after the annealing process, and the top of the projection electrode can be maintained in a very smooth state regardless of whether the annealing process is performed or not. Therefore, even when the particle diameter of the conductive particles is small, uniform pressure is applied to each of the conductive particles, and uniform particle deformation is realized.

According to the present invention, even when the particle diameter of the conductive particles contained in the anisotropic conductive film is small, it can be evenly crushed and good conduction characteristics can be obtained. Therefore, according to the present invention, it is possible to provide an electrical connecting body having excellent conduction reliability.

1 is a schematic cross-sectional view showing a structural example of an electrical connecting member.

Fig. 2 is a schematic cross-sectional view schematically showing the degree of collapse of the conductive particles when the surface of the bumps has irregularities.

3 is an optical microscope image of the vicinity of the bump in the first embodiment.

4 is an optical microscope image of the vicinity of the bumps in Comparative Example 1. Fig.

5 is another optical microscope image in the vicinity of the bump in the first embodiment.

6 is another optical microscope image in the vicinity of the bumps in Comparative Example 1. Fig.

7 is a view showing a state of crystal grains in the bump section in Example 1. Fig.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. On the other hand, in the present specification, the bump and the protruding electrode are treated as the same meaning.

Fig. 1 shows an example of an electrical connecting body. The electrical connecting body is, for example, an electronic member such as a semiconductor element electrically and mechanically connected and fixed to an electronic member such as a wiring board. Here, the case where the first electronic member is a semiconductor element (IC chip) and the second electronic member is a wiring substrate will be described as an example.

In Fig. 1, bumps (protruding electrodes) 2 are formed as connection terminals in a semiconductor element 1 as a first electronic member. On the other hand, the electrodes 4 are formed on the wiring board 3, which is the second electronic member, at positions facing the bumps 2. [ The anisotropic conductive film 5 is interposed between the semiconductor element 1 and the wiring board 3 and the conductive particles 5 contained in the anisotropic conductive film 5 are located at the portions where the bumps 2 and the electrodes 4 face each other. (6) is crushed and broken, so that electrical conduction is achieved.

The bumps 2 are formed of a conductive metal such as Au, Cu, or solder, and have a height of about 5 탆 to 50 탆. The bumps 2 can be formed by plating or the like. For example, only the surface can be plated with gold. The bump 2 is required to have surface smoothness as described later, and from this viewpoint, it is preferable to use gold plating.

In the electrical connecting body having such a structure, the surface roughness of the bumps 2 formed on the semiconductor element 1 is important. If the surface roughness of the bump 2 is large, for example, as shown schematically in FIG. 2, some of the conductive particles 6 may fit into the concave portion 2a of the connection surface of the bump 2, Is not applied and is not collapsed, so that the conductive resistance tends to become unstable. On the other hand, if the connection surface of the bump 2 is flat, all the conductive particles 6 caught between the bump 2 and the electrode 4 are uniformly pressed and crushed, and reliability of conduction is stably ensured.

From this point of view, in the present invention, the surface roughness of the bumps 2 is set to 0.05 m or less in terms of the center line average roughness Ra. In the electrical connecting body, by making the surface roughness Ra equal to or less than 0.05 mu m, it is possible to realize uniform particle deformation even when the average particle diameter of the conductive particles 6 is 4 mu m or less. The surface roughness Ra of the bumps 2 is preferably set in consideration of the average particle diameter of the conductive particles 6, and is preferably 0.02 占 퐉 or less.

The surface roughness Ra of the bumps 2 can be measured, for example, by using a contact type measuring instrument such as a surface profiler manufactured by Tencor Corporation.

Here, in the case of performing the annealing treatment in the subsequent step, in the case of the electrical connecting body, even if the surface roughness Ra before the annealing treatment can be formed to 0.05 mu m or less, the surface roughness Ra is greatly increased after the annealing treatment Lt; / RTI > On the other hand, in the electrical connecting body according to the present invention, by controlling the crystal state of the plating at the time of forming the bumps 2, the surface roughness Ra of the bump 2 is 0.05 mu m or less, more preferably 0.02 mu m or less As shown in FIG.

It is also preferable that the bumps 2 are appropriately set to the hardness in addition to the surface roughness Ra. The hardness of the bumps 2 can be designed in accordance with the kind of the conductive material used for the bumps 2 and the forming conditions for forming the plating, for example, and it is possible to realize uniform particle deformation of the conductive particles 6 It is preferable that the Vickers hardness Hv is 40 to 150. By setting the Vickers hardness Hv of the bump 2 within the range of this value, the pressing force is appropriately transmitted to the conductive particles 6 at the time of pushing the conductive particles 6 in the electrical connecting body, You can trick.

On the other hand, the anisotropic conductive film 5 used for establishing electrical connection and mechanical fixing between the bumps 2 and the electrodes 4 in the electrical connecting body is obtained by dispersing the conductive particles 6 in the insulating resin . As the insulating resin, for example, urethane resin, polyester resin, thermoplastic hot melt resin such as chloroprene, thermosetting resin such as epoxy resin and the like can be used. Examples of the epoxy resin include BPA type epoxy resin, BPF type epoxy resin, novolak type epoxy resin, and various modified epoxy resins such as rubber and urethane. These may be used alone or in combination of two or more kinds. They may be mixed and used.

Further, a latent curing agent may be added to the anisotropic conductive film 5 and heated to activate the curing agent. By adding a latent curing agent to the anisotropic conductive film 5, it is possible to impart an ignition reactivity, and the curing can be reliably and quickly performed by a heating operation at the time of connection. In this case, as the latent curing agent, an imidazole-based latent curing agent or the like can be used. For example, Novacure HX3741 (manufactured by Asahi Chemical Industry Co., Ltd.), surface-treated and microencapsulated, Nova Cure HX3921HP (manufactured by Asahi Chemical Industry Co., , Trade name Amicia PN-23 (manufactured by Ajinomoto), trade name ACR Hard and H-3615 (manufactured by ACR), and the like.

If the viscosity of the insulating resin contained in the anisotropic conductive film 5 is high, the insulating resin can not be sufficiently removed from between the electrodes to be conducted, and the reliability of conduction may be lowered. When the viscosity of the insulating resin contained in the anisotropic conductive film 5 is increased, it is necessary to increase the pressing pressure at the time of thermal curing in order to sufficiently remove the insulating resin between the electrodes to be connected. 2 or the electrode 4 may become stronger to cause cracks or the like. Therefore, the insulating resin preferably has a melt viscosity of 10 ⁸ mPa s or less at the thermocompression bonding temperature of the anisotropic conductive film 5, and more preferably 10 ⁷ mPa 쨌 s or less.

On the other hand, if the melting viscosity at the time of thermocompression bonding of the insulating resin is excessively low, there is a fear that the electrodes to be electrically connected to the conductive particles 6 are likely to deviate from each other, thereby causing a problem in terms of the trapping property. Therefore, it is preferable that the insulating resin has a melt viscosity of 10 mPa · s or more at the thermocompression bonding temperature of the anisotropic conductive film 5.

As the conductive particles 6 constituting the anisotropic conductive film 5, any known conductive particles used in this type of anisotropic conductive film can be used. For example, a metal is coated on the surfaces of particles of various metals or metal alloys such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver and gold, metal oxide, carbon oxide, graphite, glass, ceramic, Or a coating of an insulating thin film on the surface of these particles, or the like.

However, in the electrical connecting body according to the present invention, it is preferable that the surface of the resin particles is coated with a metal because the conductive particles 6 need to be pressed between the electrodes. In this case, it is preferable that the resin particles have a compression hardness of 100 to 1000 kgf / mm 2 (1 kgf / mm 2 = 9.80665 MPa) at 20% compression deformation. If the K value at 20% compression deformation of the resin particles is larger than 1000 kgf / mm < 2 >, the resin particles are not properly crushed and the height deviation of the electrode surface can not be absorbed. , The repulsive force of the conductive particles 6 becomes large, which may cause problems such as interface delamination.

Examples of the resin particles satisfying such a requirement include particles of an epoxy resin, a phenol resin, an acrylic resin, an acrylonitrile-styrene (AS) resin, a benzoguanamine resin, a divinylbenzene resin, .

The average particle diameter of the conductive particles 6 is arbitrary, but the effect of the present invention is large when the conductive particles 6 having an average particle diameter of 4 m or less are used. Therefore, the average particle diameter of the conductive particles 6 is preferably 1 mu m to 4 mu m. In addition, the grain size deviation of the conductive particles may be influenced by the hardness of the conductive particles in accordance with the flattening of the top of the projection electrodes. In the case of the present invention, it is preferable that 90% or more of the total particles are contained in the range of ± 1 μm of the average particle diameter of the conductive particles.

In the electrical connecting body having the above-described configuration, even when the particle diameter of the conductive particles 6 contained in the anisotropic conductive film 5 is as small as 4 m or less, for example, the conductive particles 6 can be uniformly pressed and crushed, Characteristics can be obtained. Therefore, it is possible to realize an electrical connecting body having excellent conduction reliability.

Next, a method of manufacturing the above described electrical connecting body will be described. In order to manufacture the electrical connection body having the above-described configuration, it is necessary to form the bumps 2 on the electrodes of the semiconductor element 1 first. The bumps 2 are formed by a plating method or the like. In order to reduce the surface roughness Ra before and after the annealing treatment to 0.05 탆 or less, it is preferable to use gold plating. Further, by selecting the plating conditions, It is necessary to make the surface of the bump 2 smooth.

Here, in the gold plating, the following gold plating solution is used to control the crystal state and smooth the surface of the bump 2 to be formed.

The gold plating solution,

a) gold compound

b) Conducting salts and buffers

c) Crystal growth agent

d) Organic polish

And the like. Examples of the gold compound include a sulfurous acid gold salt and a cyanide gold salt. Conductive salts and buffers include sulfites, phosphates, citrates, oxalates, sulphates, borates, hydrochlorides, amine salts and chelating agents. As the crystal growth agent, there are Tl, Pb, As, Bi, Co, Ni, Fe, and Sb. Examples of the organic brightener include a polymer having an NH group, that is, ethoxylated polyethyleneimine (PEIE), polyalkylimine (PAI), polyethyleneimine (PEI), and the like. The gold plating obtained from these liquid compositions is very suitable for applications in which the precipitates are dense and glossy and the surfaces of the bumps 2 formed in the present invention are smoothed.

After the formation of the bumps 2, the connection between the bumps 2 of the semiconductor element 1 and the electrodes 4 of the wiring board 3 is effected. In this case, for example, the surface of the wiring board 3 After the anisotropic conductive film 5 is attached to the semiconductor element 1 and subjected to positioning and provisional connection, the conductive particles 6 are pressed and pressed by thermocompression at a predetermined temperature and pressure, The insulating resin constituting the anisotropic conductive film 5 is cured while the bumps 2 of the anisotropic conductive film 5 and the electrodes 4 of the wiring board 3 are electrically connected. The temperature and pressure at the time of thermocompression depend on the kind of the anisotropic conductive film 5 to be used and the like, but for example, the temperature and the pressure are preferably from 180 to 220 캜 and from 30 to 120 MPa, respectively.

By carrying out the above steps, even when the particle diameter of the conductive particles 6 contained in the anisotropic conductive film 5 is small, it can be evenly crushed and good conduction characteristics can be obtained in the produced electrical connecting body.

Example

Next, concrete implementation of the electrical connecting body to which the present invention is applied will be described based on experimental results.

(Example 1)

In order to evaluate the trapping property and crushing state of the conductive particles according to the difference in the surface roughness Ra of the bumps, the bump-forming IC was mounted on the glass via the anisotropic conductive film. The anisotropic conductive film was formed by compounding the binder component so as to have a conductive particle of about 3,000 particles / square and forming it into a film. Details of each component are as follows.

Epoxy resin: manufactured by Japan Epoxy Resin Co., Ltd., trade name EP828 30 parts by weight

Phenoxy resin: manufactured by InChem, trade name: PKHH 40 parts by weight

Epoxy curing agent: manufactured by Asahi Chemical Industry Co., Ltd .; trade name: HX3941HP 30 parts by weight

Conductive particles: Ni / Au plated resin particles

Two kinds of anisotropic conductive films (anisotropic conductive film A and anisotropic conductive film B) were produced using conductive particles having an average particle diameter of 4 占 퐉 and conductive particles having an average particle diameter of 2 占 퐉 as conductive particles.

The bumps of the bump forming IC were formed by gold plating. This gold plating was carried out under the conditions of a plating temperature of 50 캜 and a current density of 0.4 A / dm ² , using Micropave Au310, manufactured by Nippon Electroplating Engineers Co., Ltd., as a gold plating solution. The resulting surface roughness Ra of the connection surface of the bumps was 0.0105 mu m. The pressing conditions at the time of mounting were as follows: an attained temperature of 200 캜, a pressure of 40 MPa, and a time of 5 seconds.

(Example 2)

A bump-forming IC was produced by changing the gold plating solution and the plating conditions of Example 1. The gold plating was carried out under the conditions of a plating temperature of 65 캜 and a current density of 0.5 A / dm ² using Neutronax 240, manufactured by Nippon Electroplating Engineers Co., Ltd., as a gold plating solution. The resulting surface roughness Ra of the connection surface of the bump was 0.004 mu m. Otherwise, the bump-forming IC was mounted on the glass through the anisotropic conductive film under the same conditions as in Example 1. [

(Comparative Example 1)

A bump-forming IC was manufactured by changing the gold plating solution and plating conditions in Example 1 and Example 2. The gold plating was carried out under the conditions of a plating temperature of 60 캜 and a current density of 0.5 A / dm ² , using Micropave Au100, manufactured by Nippon Electroplating Engineers Co., Ltd., as a gold plating solution. The resulting surface roughness Ra of the connection surface of the bumps was 0.298 mu m. Otherwise, the bump-forming IC was mounted on the glass through the anisotropic conductive film under the same conditions as in Example 1. [

(Comparative Example 2)

A bump-forming IC was manufactured by changing the gold plating solution and plating conditions of Example 1, Example 2, and Comparative Example 1. The gold plating was performed under the conditions of a plating temperature of 60 DEG C and a current density of 0.8 A / dm < ² > using gold microfabric Au660 manufactured by Nippon Electroplating Engineers Co., Ltd. as a gold plating solution. The resulting surface roughness Ra of the connection surface of the bumps was 0.130 mu m. Otherwise, the bump-forming IC was mounted on the glass through the anisotropic conductive film under the same conditions as in Example 1. [

evaluation

The conductive particles captured on the bumps were observed from the back surface of the glass using an optical microscope for each of the anisotropic conductive films A and B prepared as the examples and the comparative examples and the number of particles captured was counted to determine the total number of particles captured , And the particles having passed the crushing state were counted to determine the effective particle trapping number (range: 2000 탆 ² ). The results are shown in Table 1 and Table 2 below. Table 1 shows the results for the anisotropic conductive film A, and Table 2 shows the results for the anisotropic conductive film B.

As apparent from Table 1 and Table 2, it can be seen that the number of effective conductive particles contributing to electrical connection is greatly increased by making the surface roughness Ra of the bumps 0.05 mu m or less. Also, the total number of particles captured is equal to or larger than that of the comparative example.

Fig. 3 shows an optical microscope image of the vicinity of the bumps in Example 1 (anisotropic conductive film A), and Fig. 4 shows an optical microscope image of the vicinity of the bumps in Comparative Example 1 (anisotropic conductive film B) . Comparing these drawings, it is clear that the top portion of the bump is in a very smooth state in Embodiment 1, whereas in Comparative Example 1, the top portion of the bump is rough.

5 shows another optical microscope image in the vicinity of the bumps in Example 1 (anisotropic conductive film A), and FIG. 6 shows another optical microscope image in the vicinity of the bumps in Comparative Example 1 (anisotropic conductive film B) . It is an optical microscope image of any drawing (photograph) or bump periphery. When these figures are compared, it can be seen that in the first embodiment, the conductive particles are uniformly pressed and crushed in the entire bumps including the periphery of the bumps. On the other hand, in Comparative Example 1, the degree of crushing of the conductive particles in the periphery of the bump was insufficient.

Annealing  Impact assessment of treatment

Next, in order to evaluate the influence of the annealing process on the surface roughness Ra of the bumps, the bump forming IC manufactured as Example 1 was annealed to measure the surface roughness Ra before and after the annealing process. The results are shown in Table 3 below.

As is clear from Table 3, when the bump forming IC manufactured as Example 1 is subjected to the annealing treatment, the surface roughness Ra of the bumps after the annealing treatment is 0.0179 占 퐉, and, for example, Which is different from the conventional method such as the annealing process for the bumps formed on the surface of the substrate.

This is due to the following reasons. That is, the bumps manufactured in Example 1 are formed by accumulating grain aggregates (crystal grains) of a gold plating solution. In order to smooth the top portion, a gold plating solution is used in which crystal states are controlled so as to decrease the crystal grains. Specifically, in the bumps manufactured in Example 1, when the shape of the crystal grains in the bump cross section before the annealing treatment is measured, as shown in the distribution chart on the left side in Fig. 7, extremely fine crystal grains are gathered, As shown in the right side of the figure, the average particle size was 0.08 mu m. That is, the bumps manufactured in Example 1 are formed by extremely finely accumulating crystal grains having an average grain size of 0.1 占 퐉 or less before the annealing process. Thus, even if the annealing process is carried out, the crystal grains of the plating solution do not become large before and after the annealing process And the surface roughness Ra of the bumps is maintained at 0.05 mu m or less.

As described above, according to the present invention, the surface roughness Ra of the bumps can be made 0.05 mu m or less before and after the annealing process, and even when the particle diameter of the conductive particles contained in the anisotropic conductive film is small, this can be uniformly crushed It has been found that good conduction characteristics can be obtained in the electrical connecting body.

Claims (11)

An electrical connecting body in which a first electronic member and a second electronic member are electrically connected via an anisotropic conductive film, Crystal grains having an average grain size of 0.1 占 퐉 or less are finely deposited on the electron members of either one of them to form protruding electrodes, The top of the protruding electrode is formed by gold plating, The gold plating composition is preferably a gold compound, b) a conductive salt / buffering agent, c) a crystal growth agent, d) a) The gold compound is selected from a sulfite gold salt or cyanide cigarette, b) Conducting salts and buffering agents are selected from sulfites, phosphates, citrates, oxalates, sulphates, borates, hydrochlorides, amine salts and chelating agents, c) the crystal growth agent is selected from Tl, Pb, As, Bi, Co, Ni, Fe, and Sb, d) The organic brightener is selected from ethoxylated polyethyleneimine (PEIE), polyalkylimine (PAI), polyethyleneimine (PEI) And the top of the protruding electrode is a flat surface having a surface roughness Ra of 0.05 m or less after the annealing process. The method according to claim 1, Wherein a top portion of the protruding electrode is a flat surface having a surface roughness Ra of 0.02 占 퐉 or less after the annealing process. delete 3. The method according to claim 1 or 2, Wherein the average particle diameter of the conductive particles contained in the anisotropic conductive film is 4 占 퐉 or less. 5. The method of claim 4, Wherein the conductive particles comprise a resin particle as a core material and a conductive layer formed on the surface thereof. 6. The method of claim 5, Wherein said resin particles have a compression hardness of 20 to 100 kgf / mm < 2 > at the time of compressive deformation at 20%. A step of forming protruding electrodes having a flat surface with a surface roughness Ra of 0.05 mu m or less by gold plating with fine grains having an average particle diameter of 0.1 mu m or less finely deposited on either one of the first and second electronic members and, Interposing an anisotropic conductive film between the first electronic member and the second electronic member; Pressing and pressing the conductive particles of the anisotropic conductive film opposed to the protruded electrodes by pressing to electrically connect the first electronic member and the second electronic member, The gold plating composition is preferably a gold compound, b) a conductive salt / buffering agent, c) a crystal growth agent, d) a) The gold compound is selected from a sulfite gold salt or cyanide cigarette, b) Conducting salts and buffering agents are selected from sulfites, phosphates, citrates, oxalates, sulphates, borates, hydrochlorides, amine salts and chelating agents, c) the crystal growth agent is selected from Tl, Pb, As, Bi, Co, Ni, Fe, and Sb, d) The organic brightener is selected from ethoxylated polyethyleneimine (PEIE), polyalkylimine (PAI), polyethyleneimine (PEI) Wherein the step of forming the protruding electrode includes an annealing treatment and a flat surface having a surface roughness Ra of 0.05 mu m or less after the annealing treatment. 8. The method of claim 7, Wherein the top of the protruding electrode is a flat surface having a surface roughness Ra of 0.02 占 퐉 or less. delete 9. The method according to claim 7 or 8, Wherein a top portion of the protruding electrode is a flat surface having a surface roughness Ra of 0.02 占 퐉 or less after the annealing process. 9. The method according to claim 7 or 8, Wherein the crystal grains of the plating liquid used for forming the protruding electrodes have an average particle diameter of 0.1 mu m or less before the annealing treatment.

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