JP4128565B2 - Electrode structure of electronic circuit and manufacturing method thereof - Google Patents

Description

  The present invention relates to an electrode structure of an electronic circuit and a method for manufacturing the same, and more particularly, an electrode structure in which conductive particles are selectively self-organized on the surface of the electrode pattern, so In particular, the present invention relates to an electrode structure of an electronic circuit and a method of manufacturing the same, in which the electrical conductivity of the semiconductor device or the insulation between adjacent electrode patterns is improved and the connection contact reliability between the electronic circuits is improved.

  Circuits facing each other, for example, an anisotropic conductive film (hereinafter referred to as ACF) for contacting a circuit to electrically connect and fix the upper circuit pattern and the lower circuit pattern together. used. In the anisotropic conductive adhesive film, electric conduction is performed by conductive particles. As the degree of integration of the electronic circuit increases, the pitch between the electrode patterns becomes finer and the number of electrode patterns becomes larger. Accordingly, it is necessary to reduce the size of the conductive particles contained in the ACF, and In order to improve conductivity, it is necessary to increase the amount of conductive particles.

  However, if the size of the conductive particles is reduced, connection failure or short circuit between adjacent electrode patterns becomes a problem due to secondary aggregation, and an increase in the blending amount may cause short circuit between electrode patterns.

As a solution to such a problem, attempts have been made to use insulating coated conductive particles obtained by coating the surfaces of conductive particles with an insulating layer as ACF conductive particles (see, for example, Patent Documents 1 to 3). Patent Documents 1 and 2 propose a method in which conductive particles dispersed in a hot-melt adhesive are coated with an insulating resin that is insoluble in the adhesive. A method of encapsulating a conductive particle in an insulating resin coating shell and microencapsulating it is proposed.
US Pat. No. 6,632,532 JP 62-40183 A Japanese Patent Laid-Open No. 08-335407

  However, when such insulating coated conductive particles are used, the insulation layer on the surface of the conductive particles is not sufficiently broken or melted in the low temperature, low pressure ACF mounting process. Since the contact resistance is large and the contact between the electrode pattern and the conductive particles is incomplete, the connection reliability between the circuit electrodes is deteriorated. On the other hand, when the temperature and pressure are high, the insulating resin on the surface of the conductive particles easily dissolves, so that the adjacent conductive particles come into contact with each other and a short circuit between adjacent electrode patterns becomes a problem. Thermal and mechanical properties can be reduced.

  In order to overcome this problem, US Patent Publication No. 2001/0008169 describes a method in which conductive particles are selectively dispersed in a film layer resin so that adjacent conductive particles do not come into contact with each other. The method has the disadvantage that it is not only complicated but also uneconomical.

  An object of the present invention is to provide an electrode structure of an electronic circuit in which the connection of two circuits connected to each other is reliable in terms of electrical conductivity and adhesion, and the manufacturing process is economical.

  Another object of the present invention is to provide an electrode manufacturing method for an electronic circuit capable of selectively adsorbing conductive particles on an electrode pattern of a circuit board to cause self-organization.

  Other objects and features of the invention will be more particularly presented in the following detailed description and claims.

In order to achieve such an object, the electrode structure of the electronic circuit of the present invention includes an electrode pattern formed on a substrate and an aromatic organic compound, or both ends or main chain of an aliphatic organic compound. And a bifunctional compound having two or more functional groups having an affinity for a metal per molecule , coated on the electrode pattern, and chemically applied to the surface of the electrode pattern through one of the functional groups. and a coating layer which is coupled to, said via other functional groups see contains a chemically bonded conductive particles in said coating layer, said layer of conductive particles only on the surface of the electrode pattern of the coating layer Formed and configured.

  In such a configuration, the coating layer is chemically bonded to the electrode pattern via a functional group having a chemical bonding force with the metal, and the conductive particles are chemically bonded to the coating layer via a functional group having a chemical bonding force with the metal. Join. As a result, a conductive particle layer that is selectively self-organized only in the electrode pattern can be formed.

  The conductive particles are any one of metal single particles and particles having organic or organic / inorganic composite particles coated with metal as in claim 2.

The functional group, as claimed in claim 3, selected thiol group, a carboxyl group and derivatives thereof, hydroxyl groups, amine groups and derivatives thereof, metal acids, from base functional group and an ionic bond capable functional group Any one of them.

The method for producing an electrode of an electronic circuit according to the present invention includes a functional group having an affinity for a metal in a substrate on which an electrode pattern is formed, in an aromatic organic compound, or in both ends or main chain of an aliphatic organic compound. Coating two or more bifunctional compounds per molecule to chemically bond the bifunctional compound to one of the functional groups on the surface of the electrode pattern; and Cleaning to remove the bifunctional compound on the substrate portion other than the electrode pattern; coating the substrate with conductive particles; and bonding the bifunctional compound to only the surface of the electrode pattern; a step of chemically bonded via the other of said functional groups and a conductive particle, seen including a the steps of removing the conductive particles of the substrate portion other than the electrode pattern by washing the substrate, wherein Characterized in that so as to form a layer of the conductive particles only on the surface of the electrode pattern.

  According to the present invention, a conductive particle layer that is selectively self-organized is formed only on the surface of the electrode pattern formed on the substrate, thus solving the problem of short circuit between adjacent electrode patterns due to contact between adjacent conductive particles. In addition, the electrical conductivity of each electronic circuit can be improved and the contact reliability can be improved.

In addition, according to the electrode manufacturing method of the present invention, after coating the electrode pattern with a bifunctional compound containing a functional group having a chemical bonding force with a metal, washing is performed to remove the bifunctional compound , and then coating is performed. The manufacturing process is very simple and economical because it is only necessary to wash the bifunctional compound after the conductive particles are coated to remove the conductive particles.

  FIG. 1 shows a schematic structure of an electronic circuit board including an electrode structure having an electrode pattern in which self-organized conductive particles according to the present invention are formed.

In the figure, the lower circuit board and the upper circuit board are coupled to each other in the direction of the arrow in the figure via the adhesive film 2. The electrode pattern 1 formed on the surface of the lower circuit board is coated with a coating layer (not shown) made of a bifunctional compound having a functional group having a chemical bonding force with a metal. A part of the functional group (not shown) of the bifunctional compound is chemically bonded to the surface of the electrode pattern 1, and the conductive particle 3 is chemically bonded to the other functional group 4. As a result, the conductive particles 3 are adsorbed only on the surface of the electrode pattern 1 and selectively self-assembled.

In this way, the surface of the electrode pattern of the electronic circuit is coated with a bifunctional compound that can spontaneously bind to the metal component of the conductive particles 3, and the conductive particles are directly adsorbed on the surface of the bifunctional compound. Of the two functional groups, one functional group is bonded to the electrode pattern, the other functional group is bonded to the metal conductive particles, and the conductive particles are simply selectively aligned only on the surface of the electrode pattern. An organized conductive layer can be formed.

  According to such a configuration, the current passes only in the mutual direction of the electrode pattern, the insulation characteristic in the direction perpendicular to the electrode pattern is maintained, and the high integration of the electronic circuit without the short circuit problem between the electrode patterns due to the contact between the adjacent conductive particles. The contact reliability between electronic circuits can be improved. In addition, the electrode manufacturing process is simple and economical.

Hereinafter, the present invention will be described more specifically through examples.

Bifunctional compounds and metal conductive particles

In one example of the present invention described later, propanedithiol having thiol groups having strong affinity for metal at both ends was used as the bifunctional compound. However, the present invention is not limited to this, for example, an aromatic organic compound having 2 to 1000 carbon atoms, or a functional group having affinity for a metal in both ends or main chain of an aliphatic organic compound. As long as there are two or more groups per molecule, examples of such functional groups include thiol groups, carboxyl groups and derivatives thereof, hydroxyl groups, amine groups and derivatives thereof, metal acids, Either a basic functional group or a functional group capable of ionic bonding can be used. Representative examples of such organic compounds include ethanedithiol, propanedithiol, butanedithiol, pentanedithiol, hexanedithiol, heptanedithiol, octanedithiol, decanedithiol, ethanediol, propanediol, butanediol, pentanediol, hexane. Diol, heptanediol, octanediol, decanediol, ethanedicarboxylic acid, propanedicarboxylic acid, butanedicarboxylic acid, pentanedicarboxylic acid, hexanedicarboxylic acid, heptanedicarboxylic acid, octanedicarboxylic acid, decanedicarboxylic acid, diaminoethane, diaminopropane, diamino Butanediol, diaminopentane, diaminohexane, diaminoheptane, diaminooctane, diaminodecane, ethane diphosphate (eth anediphosphoric acid), propane diphosphate, butane diphosphate, pentane diphosphate, hexane diphosphate, heptane diphosphate, octane diphosphate and decane diphosphate, and these acid-base reactions. And organometallic compounds resulting from the formation of kimonos with metals.

Further, as the metal conductive particles, in one embodiment of the present invention, polystyrene particles coated with gold having a diameter of 5 μm were used. However, the present invention is not limited to this, and organic or organic / inorganic composite particles coated with a metal having an affinity for any of the above organic compounds having a functional group, or particles made of only a metal. Any of these can be used. As the metal component, conductive metals including silver, copper, nickel and the like can be used in addition to the above-described gold.

Reaction of electrode pattern with compound having two functional groups

A substrate using copper as an electrode pattern is treated with a propanedithiol solution for 24 hours, for example, by spraying a propanedithiol solution on the substrate or dipping in a propanedithiol solution. Of these functional groups, one thiol group was bonded to react with an unmasked electrode pattern of the substrate. At this time, the other one thiol group remains without reacting.

Then, the said board | substrate was wash | cleaned 3-5 times with ethanol, and the propane dithiol physically adsorb | sucked to board | substrate parts other than an electrode pattern was removed. At this time, the number of washings may be any number that can sufficiently remove propanedithiol physically adsorbed on the substrate portion other than the electrode pattern.

Selective self-organization of metal conductive particles

Unreacted thiol groups of propanedithiol bonded to the copper electrode pattern and metal conductive particles were reacted in an ethanol solution for 24 hours at room temperature. After the reaction, it was washed 3 to 5 times with ethanol to remove the metal conductive particles physically adsorbed on the substrate portion other than the electrode pattern. At this time, the number of washings may be any number that can sufficiently remove propanedithiol physically adsorbed on the substrate portion other than the electrode pattern. The result of Fig.2 (a) was confirmed using the electron microscope from the board | substrate obtained by such a method. From FIG. 2A, it can be seen that the conductive particles (fine circular particles in the figure) are selectively adsorbed only on the metal electrode pattern (rod-like portion in the figure).

  For comparison, the electrode pattern not reacted with propanedithiol and the metal conductive particles were reacted in an ethanol solution for 24 hours at room temperature. The result of FIG.2 (b) was confirmed using the electron microscope from the board | substrate obtained by such a method. As shown in FIG. 2B, the conductive particles are not selectively adsorbed only on the metal electrode pattern (the bar-shaped portion in the figure) and are also present in the insulating portion (the portion other than the electrode pattern) between the adjacent electrode patterns. I understand. In addition, since the conductive particles on the surface of the electrode pattern not reacted with propanedithiol have a weak physical bonding force, they are mostly removed in the cleaning process to form a conductive particle layer on the surface of the electrode pattern. I couldn't.

The figure which shows the typical structure of the electronic circuit board which shows one Embodiment of the electrode structure of the electronic circuit which concerns on this invention It is an electron micrograph of the electrode pattern of an electronic circuit board, (a) is an electron micrograph of an electrode pattern coated with a bifunctional compound containing a functional group having an affinity for metal, and (b) is an affinity for metal. Electron micrograph of electrode pattern not coated with bifunctional compound containing functional group

Explanation of symbols

1 Electrode Pattern 2 Adhesive Film 3 Conductive Particle 4 Functional Group

Claims (4)

An electrode pattern formed on the substrate;
The electrode pattern comprising a bifunctional compound in which two or more functional groups having an affinity for a metal exist in one molecule per molecule in an aromatic organic compound or in both ends or main chain of an aliphatic organic compound A coating layer coated thereon and chemically bonded to the surface of the electrode pattern via one of the functional groups ;
Look containing a chemically bonded conductive particles in said coating layer through the other of said functional groups of the coating layer,
An electrode structure of an electronic circuit , wherein the conductive particle layer is formed only on the surface of the electrode pattern .   2. The electrode structure of an electronic circuit according to claim 1, wherein the conductive particles are any one of metal single particles and particles in which metal is coated on the surface of organic or organic / inorganic composite particles. The functional group is any one selected from thiol group, carboxyl group and derivatives thereof, hydroxyl group, amine group and derivatives thereof, metal acid, base functional group and functional group capable of ionic bonding. The electrode structure of the electronic circuit according to claim 1, wherein the electrode structure is an electronic circuit. There are two or more functional groups having an affinity for a metal per molecule in an aromatic organic compound or in both ends or main chain of an aliphatic organic compound on a substrate on which an electrode pattern is formed. by coating the functional compound, and a step of chemically bonding said through one of the functional groups bifunctional compounds on the surface of the electrode pattern,
Cleaning the substrate to remove the bifunctional compound on the substrate portion other than the electrode pattern;
Coating the substrate with conductive particles, and chemically bonding the bifunctional compound bonded to only the surface of the electrode pattern and the conductive particles through the other of the functional groups ;
Cleaning the substrate to remove the conductive particles on the substrate portion other than the electrode pattern;
Only including,
An electrode manufacturing method for an electronic circuit , wherein the conductive particle layer is formed only on the surface of the electrode pattern .

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