JP2009070650A - Functional conductive coating, its manufacturing method, and printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-temperature setting functional conductive coating high in adhesion with a resin board or copper foil, good in conductivity, and capable of soldering; to provide its manufacturing method and a printed wiring board. <P>SOLUTION: The functional conductive coating contains 70-99 wt.% metallic powder comprising at least powder of Ag-coated Ni powder or Ag powder, and has thermosetting resin containing chelate modified epoxy resin. The chelate modified epoxy resin in the thermosetting resin is contained 10-20 wt.%, and formed by adding an unsaturated fatty acid. The printed wiring board has a conductive path formed by applying the functional conductive coating to an insulating board. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a functional conductive paint having a soldering function, adhesion between a copper foil and conductivity, a method for producing the same, and a printed wiring board.

  Conductive paint containing metal powder is widely used because it is used in many fields, such as bonding of electronic components and wiring, jumper wires using printed wiring boards, and terminal lead wires for printed resistors. It has been studied.

  Conventionally, resin binder-type low-temperature curing conductive paints in which metal powders such as silver, copper, and nickel are mixed with resin are used as printed wirings and conductive adhesives for electronic circuits. However, these conductive paints contain about 20% resin by weight, so the volume ratio is overwhelmingly high, and any of the commercially available conductive paints cannot be soldered. is there.

  Moreover, although the electrically conductive paint which can be soldered as disclosed in Patent Documents 1 and 2 has been proposed, it does not have sufficient performance. Furthermore, as disclosed in Patent Document 3, in order to realize rust prevention and proper printability of metal powder, there is a conductive paint to which an unsaturated fatty acid is added. However, when a phenol resin is used for the binder and an unsaturated fatty acid is added, the adhesion with the copper foil is deteriorated.

On the other hand, since most of the recent electronic circuits have been surface-mounted, conductive paints that can be soldered to surface-mounted electronic components and have good adhesion to wiring formed of copper foil through through holes Development of is strongly desired.
Japanese Patent Laid-Open No. 7-14429 JP 2002-212492 A JP 2006-28213 A

  The present invention has been made in view of the above-described background art, and has a low adhesion property and a low-curing functional conductive paint that has high adhesion to a resin substrate or copper foil, good conductivity, and solderability. An object of the present invention is to provide a printed wiring board.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention, in the process of manufacturing a paint by mixing a metal powder, a binder, and an organic solvent, Ag coated Ni powder alone or Ag Using a mixture of coated Ni powder and Ag powder, a conductive paint was formed using a mixture of a chelate-modified epoxy resin and a phenol resin and / or a reaction product of a chelate-modified epoxy resin and a phenol resin as a binder. The pattern of the conductive paint obtained by printing this conductive paint on an insulating substrate and baked and cured at a low temperature of about 150 to 170 ° C. exhibits excellent conductivity, good solder wettability, and good bonding properties with solder. It has been found that the adhesiveness with the copper foil is also excellent, and the present invention has been completed.

  The present invention is a functional conductive paint comprising a metal powder comprising at least one of an Ag-coated Ni powder and an Ag powder, a thermosetting resin containing a chelate-modified epoxy resin, and an unsaturated fatty acid added thereto. The thermosetting resin is a mixture of a chelate-modified epoxy resin and a phenol resin, and / or a reaction product of a chelate-modified epoxy resin and a phenol resin. The unsaturated fatty acid is oleic acid and / or linoleic acid.

  Furthermore, the content of the metal powder is 70 to 99 wt. %, And the chelate-modified epoxy resin in the thermosetting resin is 10 to 20 wt. %.

  The present invention also includes mixing a metal powder composed of at least one of Ag-coated Ni powder and Ag powder and a thermosetting resin containing a chelate-modified epoxy resin, adding an unsaturated fatty acid and a curing agent, and using these as a solvent. This is a method for producing a functional conductive paint that dissolves to form a reaction product of a chelate-modified epoxy resin and a phenol resin.

  Further, according to the present invention, a metal powder composed of at least one of an Ag-coated Ni powder and an Ag powder is added to 70 to 99 wt. % Containing a thermosetting resin containing a chelate-modified epoxy resin, and the chelate-modified epoxy resin in the thermosetting resin is 10 to 20 wt. % Is a printed wiring board in which a functional conductive paint formed by adding an unsaturated fatty acid is applied on an insulating substrate to form a conductive path.

  According to the functional conductive paint of the present invention, in the manufacture of electronic circuits including printed wiring using a resin substrate or the like, the electronic components such as chip parts, circuit components and solder wiring between printed wiring and the like, through holes, etc. Since it can be bonded to all copper foils, an electronic circuit can be easily manufactured.

  Furthermore, by using the functional conductive paint of the present invention, it is possible to manufacture electronic circuits stably and simply with printed wiring at a low temperature of about 150 to 170 ° C., greatly simplifying the circuit board manufacturing process. Can be Therefore, a part of the conductor circuit for surface mounting by the conventional copper foil etching process is a printed wiring according to the present invention, thereby simplifying circuit manufacture and significantly improving cost and yield. Further, the amount of waste liquid can be reduced, the cost can be reduced, and the environmental load can be reduced. This greatly contributes to the technical field.

  In addition, since a thin natural oxide film is formed on the surface of the metal powder in the conductive paint by moisture or oxygen in the air, stable electrical conduction may not be obtained. In the conductive conductive paint, since the unsaturated fatty acid also removes the oxide film, an electronic circuit having a very small resistance value can be formed.

  Hereinafter, embodiments of the present invention will be described in detail. Examples of the metal powder used in the functional conductive paint of the present invention include Ag-coated Ni powder, Cu powder, Ag powder, Ni powder, and Al powder. Among these, Ag-coated Ni is used from the viewpoint of solderability. A powder or a mixed powder of Ag-coated Ni powder and Ag powder is preferred. The content of the metal powder is preferably 70 to 99 wt.%, More preferably 70 to 95 wt.% In the entire functional conductive paint.

  Examples of the thermosetting resin contained in the binder used in the functional conductive paint of the present invention include an epoxy resin, a melamine resin, a phenol resin, a polyimide resin, and a polycarbonate resin. Among these, from the viewpoint of coating film characteristics. Chelate-modified epoxy resins and phenol resins are preferred. The content of the thermosetting resin is preferably 1 to 30 wt.%, More preferably 5 to 15 wt.% In the entire functional conductive paint.

  Curing agents such as imidazole, dicyandiamide, and aromatic polyamine are added to the binder. Of these, imidazole is preferred. Further, the content of the curing agent is preferably 1 to 30 wt.%, More preferably 2 to 20 wt.% In the entire functional conductive paint.

  The organic solvent used in the functional conductive paint of the present invention is not particularly limited as long as the thermosetting resin is uniformly dispersed in the paint, and examples thereof include butyl carbitol, methyl carbitol, and Solvesso 150. An organic solvent may be added to adjust the viscosity so that screen printing can be performed (about 200 to 500 poise). Of these organic solvents, butyl carbitol is preferable, and the content thereof is preferably 0.1 to 20 wt.%, More preferably 0.5 to 15 wt.% In the entire functional conductive paint.

  Furthermore, in the functional conductive paint of the present invention, unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid may be dissolved for the purpose of promoting the destruction of the oxide film on the surface of the metal powder. Of these unsaturated fatty acids, oleic acid and linoleic acid are preferable, and the content is preferably 0.1 to 5.0 wt.% In the entire functional conductive paint, and more preferably 0.5 to 3 0.0 wt.%.

  The functional conductive paint of the present invention having the above composition is mixed in a desired shape by various methods such as printing, spraying, brush coating, etc., after mixing well until the material blended in a revolving mixer such as a hybrid mixer is uniformly dispersed. It can be applied on an insulating substrate. And an electronic circuit can be simply formed by baking for 5 to 30 minutes at the temperature of 150-170 degreeC.

  Next, the manufacturing method of the printed wiring board using the functional conductive paint of this invention is shown. First, the paint of the present invention is deposited on a resin substrate for printed wiring by a screen printing method or the like and dried. Thereafter, baking is performed at a temperature of 150 to 170 ° C. Thereby, the printed wiring electrode from which favorable electrical continuity was taken is manufactured. Since the functional conductive paint of the present invention is excellent in solder adhesion between an electronic component and a printed wiring, a surface-mount electronic circuit can be easily produced.

EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not restrict | limited to a following example. First, the following ingredients are prepared and mixed.
Metal powder containing 10 wt% of Ag powder in Ag coated Ni powder (Ag coat amount 15 wt%) 88 parts by weight Oleic acid 2 parts by weight Imidazole-added chelate-modified epoxy resin (as solid content) 0-2 parts by weight (chelate-modified epoxy resin Addition amount of imidazole to 20 phr)
Phenolic resin (as solids) 8-10 parts by weight Butyl carbitol 2.5 parts by weight

A conductive coating containing these materials was screen-printed on a glass epoxy resin substrate with a zigzag pattern shown in FIG. 1 and baked at 160 ° C. for 30 minutes to form a conductive path.
1 is a zigzag pattern for screen printing, the line width is 2 mm, and the magnification is 184 times. Therefore, the volume resistivity ρ is obtained from the following equation.
ρ = (Rx / 184) × d (Ω · cm)
However, Rx: Resistance value between both ends of the zigzag pattern (Ω)
d: Sample pattern film thickness (cm)

Outline of materials used in Examples Ag coated Ni powder YNA series manufactured by Yokozawa Metal Industry Co., Ltd. (custom product)
Ag powder AG-3500M manufactured by Sakai Chemical Industry Co., Ltd.
Chelate-modified epoxy resin manufactured by Adeka Corporation EP-49-23
Epoxy resin curing agent EH-4344S manufactured by ADEKA CORPORATION (can also be used as a curing accelerator for phenolic resin)
AH-880 made of phenolic resin Lignite Co., Ltd.
Oleic acid Wako Pure Chemical Industries, Ltd. First grade reagent butyl carbitol Wako Pure Chemical Industries, Ltd. Special grade reagent hybrid mixer KEYENCE Corporation

Under the above conditions, the performance when the amount of the chelate-modified epoxy (EP) resin relative to the phenol resin was changed was evaluated. The evaluation results are shown in Table 1.

  According to Table 1, the amount of the chelate-modified epoxy resin relative to the phenol resin is 10 to 20 wt. % Gave favorable results. As a result, it was confirmed that the functional conductive paint of the present invention has good solderability and adhesion with copper foil, and can be used for the production of electronic circuits or the formation of electronic circuits.

A zigzag pattern for screen printing is shown.

Claims (6)

  A functional conductive paint comprising a metal powder comprising at least one of Ag-coated Ni powder and Ag powder, a thermosetting resin containing a chelate-modified epoxy resin, and an unsaturated fatty acid added thereto.   The functional conductive paint according to claim 1, wherein the thermosetting resin is a mixture of a chelate-modified epoxy resin and a phenol resin.   The functional conductive paint according to claim 1 or 2, wherein the unsaturated fatty acid is oleic acid and / or linoleic acid.   The content of the metal powder is 70 to 99 wt. %, And the chelate-modified epoxy resin in the thermosetting resin is 10 to 20 wt. The functional conductive paint according to claim 1, which is%.   A metal powder composed of at least one of Ag-coated Ni powder and Ag powder and a thermosetting resin containing a chelate-modified epoxy resin are mixed, an unsaturated fatty acid and a curing agent are added, and these are dissolved in a solvent. A method for producing a functional conductive paint that forms a reaction product of a resin and a phenol resin. A metal powder composed of at least one of Ag-coated Ni powder and Ag powder was added in an amount of 70 to 99 wt. % Containing a thermosetting resin containing a chelate-modified epoxy resin, and the chelate-modified epoxy resin in the thermosetting resin is 10 to 20 wt. %, And a conductive wiring formed by adding a functional conductive paint to which an unsaturated fatty acid is added on an insulating substrate to form a conductive path.

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