WO2010041668A1

WO2010041668A1 - Flux, conductive paste, bonded component, and method for producing bonded component

Info

Publication number: WO2010041668A1
Application number: PCT/JP2009/067430
Authority: WO
Inventors: 和雄河口; 秀俊宮本; 毅渡邉
Original assignee: Jsr株式会社
Priority date: 2008-10-07
Filing date: 2009-10-06
Publication date: 2010-04-15
Also published as: JPWO2010041668A1; TW201016652A

Abstract

Disclosed is a flux which is capable of bonding a substrate and an electronic component or the like and does not leave residues after bonding (such as soldering). Also disclosed are a conductive paste containing the flux, a bonded component formed by bonding constituent members using the conductive paste and having high bonding reliability, and a method for producing the bonded component. The flux contains an aromatic compound which has two phenolic hydroxy groups in two positions of each aromatic ring, said two positions being next to each other or having one position therebetween. The aromatic compound has a melting point not less than 23˚C at 1 atm.

Description

Flux, conductive paste, bonded component and method for manufacturing bonded component

The present invention relates to a flux used for soldering with an electronic component or the like, a conductive paste containing the same, a bonded component using the same, and a method of manufacturing the bonded component.

Conventionally, flux is used in soldering electronic components to a component mounting board. This flux contains an organic acid such as rosin or a halogen compound for the purpose of removing an oxide film on the substrate. If a flux residue remains after soldering using such a solder paste containing flux, there is a problem that the soldered substrate is gradually corroded due to the corrosive action of the flux residue. Therefore, after the soldering is completed, the soldered substrate needs to be cleaned for the purpose of removing the flux residue. For the cleaning, a chlorofluorocarbon solvent is generally used. However, in recent years, from the viewpoint of environmental pollution, chlorofluorocarbons have been promoted, and water-based cleaning in which water is used for cleaning, and low-residue non-cleaning fluxes with low solid content that do not require cleaning after soldering are used.
However, in the case of water-based cleaning, since water is used for cleaning, there is a problem that the water used for cleaning is contaminated with heavy metals. In addition, for semiconductor elements having a connection pitch structure that has been further miniaturized in the future, there is a problem that water-based cleaning has poor cleaning properties, and therefore, a low-residue non-cleaning flux that does not require cleaning is often used. .

In addition, in fluxes used in the manufacture of electronic circuit devices that require a plurality of reflow processes, the bonding strength must be maintained without lowering the bonding strength due to solder even after a plurality of reflows. There is.

As a low-residue flux, Patent Document 1 uses a solvent that substantially does not evaporate before soldering and exhibits an activity of thermally decomposing and reducing and removing the oxide film on the soldering surface during soldering. A soldering flux is disclosed. This solvent is a solvent that gradually evaporates after soldering, and a low residue flux is obtained by using this solvent.

Japanese Patent Laid-Open No. 8-112692

In solder paste, the material composition of the paste is generally composed of solder powder, solvent, solid content (rosin, activator, etc.). The conventional non-cleaning flux described in Patent Document 1 has been devised such as reducing the solid content and not containing a halide. However, after soldering, the resin component or activator component such as rosin must be used. Residues such as these may be generated.

Moreover, when manufacturing an electronic circuit device that requires a plurality of reflow processes, the number of reflow processes can be reduced if the solder paste used is an adhesive paste that does not melt the solder. Soldering can be performed without applying thermal stress. Accordingly, there is a demand for development of a solder paste having an adhesive force without melting the solder.

The present invention solves the above-described problems. Specifically, the flux has adhesiveness and does not generate a residue after joining (soldering, etc.), and a conductive paste containing this flux, and using the same It is an object of the present invention to provide a joining component formed by joining constituent members with high joining (soldering, etc.) reliability and a method for manufacturing the joining component.

The present invention is as follows.
1. An aromatic compound having two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring or having two phenolic hydroxyl groups at two positions of the position number of one jump of the aromatic ring Containing flux,
The flux characterized by the melting point of the aromatic compound under 1 atm being 23 ° C. or higher.
2. The vaporization temperature of the aromatic compound is 100 ° C. or higher under 1 atm. Flux described in
3. An aromatic compound having two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring is a compound represented by the following general formula (1), and
In the above 1., the aromatic compound having two phenolic hydroxyl groups at two positions of the position number of one jump of the aromatic ring is a compound represented by the following general formula (2). Or 2. Flux described in

[In the general formulas (1) and (2), R represents an alkyl group, and n represents an integer of 0 to 4. ]
4). An aromatic compound having two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring is a compound represented by the following general formula (3) or the following general formula (4), and
In the above 1., the aromatic compound having two phenolic hydroxyl groups at two positions of the position number of one jump of the aromatic ring is a compound represented by the following general formula (5). Or 2. Flux described in

[In the general formulas (3) to (5), R represents an alkyl group, and n represents an integer of 0 to 4. ]
5). The above-mentioned 1. containing two or more kinds of compounds as the aromatic compound. To 4. The flux according to any one of the above.
The above 1. which is a solid under an atmosphere of 6.1 atm and 23 ° C. To 5. The flux according to any one of the above.
7). Above 1. To 6. A conductive paste comprising the flux according to any one of the above and conductive metal particles.
8). The constituent member and the other constituent members are the above-mentioned 7. Joined parts characterized by being joined using the conductive paste described in 1.
9. A method of manufacturing a joined part in which a constituent member and another constituent member are joined,
A conductive paste application step of applying the conductive paste according to claim 7 to the constituent members;
A component mounting process for mounting other components on the applied conductive paste;
A method for manufacturing a joined part, comprising:

The flux of the present invention has two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring, or two phenolic hydroxyl groups at two positions of one position number of the aromatic ring. A flux containing an aromatic compound having a melting point, and the melting point of the aromatic compound at 1 atm. Is 23 ° C. or higher. Can be removed. Moreover, this flux has adhesiveness and can fix components only with a flux. Therefore, even in a joining component (such as an electronic circuit device) that requires a plurality of component mounting processes and reflow processes, positioning between electronic components is performed without melting conductive metal particles (solder, etc.). And can be joined (soldered or the like) with a smaller number of reflows. Furthermore, the flux of the present invention contains the aromatic compound, so that the residue of the flux after joining components such as electronic components to the substrate is suppressed, and it can be made a non-cleaning flux.
Further, when the vaporization temperature of the aromatic compound is 100 ° C. or higher under 1 atm, a flux residue can be made more difficult to remain.
In addition, the conductive paste of the present invention contains the flux of the present invention, whereby flux residue generated after bonding electronic components or the like to the substrate is suppressed, and a cleaning step after bonding can be made unnecessary.
In addition, since the component parts and the other component members are bonded using the conductive paste of the present invention, the bonded component of the present invention can be bonded with a small number of reflows. Excessive thermal stress on the constituent members is reduced, and a highly reliable joining component can be provided.

It is a fragmentary sectional view of the joined component concerning the present invention. It is a fragmentary sectional view which shows the manufacturing method of the joining components using the electrically conductive paste containing the flux which concerns on this invention.

1; substrate, 2a, 2b; land, 3a, 3b, 13a, 13b; conductive paste, 4; electronic component, 5a, 5b; external electrodes, 23a, 23b; conductive bonding material (solder, etc.).

[1] Flux The flux of the present invention has two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring or two positions of position numbers of one jump of the aromatic ring. A flux containing an aromatic compound having two phenolic hydroxyl groups (hereinafter simply referred to as “aromatic compound”), wherein the aromatic compound has a melting point of 23 ° C. or more under 1 atm. To do.

The aromatic compound has two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring, or two phenolic hydroxyl groups at two positions of one position number of the aromatic ring. Have When the flux of the present invention contains this aromatic compound, the oxide film formed on the surface of the metal such as the substrate to be soldered can be reduced and the oxide film can be removed. This improves the so-called solder wettability.
Moreover, the flux of this invention has adhesiveness in addition to having said reducing property by including this aromatic compound. Since it has adhesiveness, components can be bonded to each other only by flux (without using molten solder).
Examples of the constituent member include various substrates such as a component mounting substrate and a chip mounting substrate, and various electronic components such as an electronic circuit module, a flip chip IC, and a semiconductor chip (the same applies hereinafter).
Furthermore, since the flux of the present invention contains this aromatic compound, in addition to the reducing property and the adhesive property, it is extremely difficult to remain as a residue after joining, and it is necessary to perform a flux cleaning step that has been conventionally required. Absent.

The melting point of the aromatic compound at 1 atm is 23 ° C. or higher. Usually, this melting point is 250 ° C. or lower. When the melting point of the aromatic compound is 23 ° C. or higher, good adhesion can be maintained even at room temperature. The melting point at 1 atm is preferably 25 to 230 ° C., more preferably 100 to 200 ° C., and still more preferably 120 to 200 ° C.

Examples of the position number in the case of having two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring in the aromatic compound include 1st position, 2nd position, 2nd position, 3rd position and 3rd position. And 4th position.
Moreover, as the position number when there are two phenolic hydroxyl groups at two positions of the position number of one jump of the aromatic ring in the aromatic compound, for example, the 1st position, the 3rd position, the 2nd position and 4th position Rank.

As long as the said aromatic compound has the said characteristic, the structure is not specifically limited. Examples of the skeleton of the aromatic compound include benzene, naphthalene, acenaphthene, and the like. Of these skeletons, benzene and naphthalene are preferred. In particular, compounds represented by the following general formulas (1) to (5) are more preferable.

[In the general formulas (1) to (5), R represents an alkyl group, and n represents an integer of 0 to 4. ]

The number of carbon atoms of the alkyl group in R in the general formulas (1) to (5) is preferably 1 to 10, more preferably 1 to 8, and still more preferably 1 to 5. The structure of this alkyl group is not particularly limited, and may be linear or have a side chain (branched). Examples of the alkyl group include a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, pentyl group, isopentyl group, Neopentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group and the like can be mentioned.
In the general formulas (1) to (5), n is preferably 0 to 2, more preferably 0 or 1. When n in the general formulas (1) to (5) is n ≧ 2, each R may be the same or different.

That is, as a preferable compound, the compound of the formula (1) is preferably a compound of the following formula (6) in which n is 0 or 1, and the compound of the formula (2) is in the following of n of 0 or 1 A compound of formula (7) is preferred.

[In the general formulas (6) to (7), R represents a hydrogen atom or an alkyl group. ]

Further, as a preferable compound, the compound of the formula (3) is a compound of the following formula (8) in which n is 0 or 1, and the R is bonded to a benzene ring having no phenolic hydroxyl group. Preferably, the compound of the formula (4) is a compound of the following formula (9) in which n is 0 or 1, and the R is bonded to a benzene ring having no phenolic hydroxyl group. Preferably, the compound of the formula (5) is a compound of the following formula (10) in which n is 0 or 1 and the R is bonded to a benzene ring having no phenolic hydroxyl group.

[In the general formulas (8) to (10), R represents a hydrogen atom or an alkyl group. ]

Specific examples of such aromatic compounds include resorcinol, 4-methylcatechol, 4-t-butylcatechol, 3-methylcatechol, 5-methylresorcinol, 5-t-butylresorcinol, 1,2 -Dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene and the like. These may use only 1 type and may use 2 or more types together. Of these aromatic compounds, 4-methylcatechol and 4-t-butylcatechol are preferred. These are preferable because of their strong ability to reduce to metal oxides compared to other aromatic compounds.

When two kinds of aromatic compounds are used in combination, it is preferable to use 4-methylcatechol and 4-t-butylcatechol in combination among the aromatic compounds. When these are used in combination, it is preferable because the reducing ability to metal oxide is stronger than other combinations.
Furthermore, the blending ratio when used in combination is not particularly limited, but when the total of 4-methylcatechol and 4-t-butylcatechol is 100 mol%, the ratio of 4-methylcatechol is 30 to 80 mol%. It is preferable to do. In this range, a particularly excellent reducing effect can be obtained. The range is more preferably 40 to 70 mol%, and particularly preferably 50 to 60 mol%.

The vaporization temperature of the aromatic compound is preferably 100 ° C. or higher under 1 atm. When the temperature is 100 ° C. or higher, the aromatic compound is vaporized when joining (soldering or the like), no residue is generated, and a non-cleaning flux can be obtained. The vaporization temperature under 1 atm is usually 400 ° C. or lower, more preferably 150 ° C. or higher, and further preferably 200 ° C. or higher.
The vaporization temperature under 1 atm is a temperature at which a decrease in weight is observed when the temperature is raised under the condition of 1 atm. This vaporization temperature is measured by the following method. That is, using a differential thermal balance (TG / DTA), the temperature inside the system was raised under nitrogen, and the temperature at which weight loss due to flux vaporization (usually 5 mass% or more of the entire sample) was first observed was The vaporization temperature.

The amount of the aromatic compound contained in the flux of the present invention is not particularly limited and may be contained as a part of the flux or may constitute the entire amount of the flux. That is, for example, when the total flux is 100% by mass, the aromatic compound can be contained in an amount of 70 to 100% by mass. If content of the said aromatic compound is this range, it can be set as the flux excellent in reducibility and low residue property. The content is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass.

The flux of the present invention can contain other components in addition to the aromatic compound as long as the object of the present invention is achieved. Examples of other components include solvents, activators, and thixotropic agents. These may use only 1 type and may use 2 or more types together.

Examples of the solvent include alcohols, esters, ethers and hydrocarbons. Examples of the solvent include monohydric alcohols such as isopropanol and butanol; dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, pentanediol, and hexanediol. Ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether and propylene glycol monobutyl ether Alkyl ethers; propylene glycol di Propylene glycol dialkyl ethers such as chill ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate Propylene glycol monoalkyl ether acetates such as; cellosolves such as ethyl cellosolve and butyl cellosolve; carbitols such as butyl carbitol; lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate and isopropyl lactate; N-propyl acetate, isopropyl acetate, n-butyl acetate, Aliphatic carboxylic acid esters such as isobutyl acid, n-amyl acetate, isoamyl acetate, isopropyl propionate, n-butyl propionate, isobutyl propionate; methyl 3-methoxypropionate, ethyl 3-methoxypropionate, 3-ethoxy Other esters such as methyl propionate, ethyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate; aromatic hydrocarbons such as toluene, xylene; 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone, etc. Ketones; amides such as N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone; and lactones such as γ-butyrolactone. These may use only 1 type and may use 2 or more types together.

The flux of the present invention can contain a solvent. The amount of the solvent is not particularly limited, but when the total amount of aromatic compounds is 100 parts by mass, 0.1 to 100,000 parts by mass can be used, preferably 1 to 10,000 parts by mass, and more preferably Is 10 to 1000 parts by mass. The viscosity of the flux can be adjusted by the content of the solvent. That is, an appropriate viscosity can be selected according to the flux application method, and the viscosity can be adjusted by the amount of solvent in the above range.

Examples of the activator include amine salts of hydrochloric acid and hydrobromic acid, and carboxylic acids and amine salts thereof. Examples of the activator include primary amines such as methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine; dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n Secondary amines such as butylamine; Tertiary amines such as trimethylamine, triethylamine, tri-n-propylamine and triisopropylamine; Hydrogen chlorides such as alkanolamines such as monoethanolamine, diethanolamine and triethanolamine Acid salts and hydrobromides, as well as oxalic acid, malonic acid, succinic acid, adipic acid, glutaric acid, diethyl glutaric acid, pimelic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, diglycolic acid, caprin Acid, lauric acid, myris Acid, palmitic acid, linoleic acid, oleic acid, stearic acid, arachidic acid, behenic acid, linolenic acid and other aliphatic carboxylic acids; benzoic acid and other aromatic acids; hydroxypivalic acid, dimethylolpropionic acid, citric acid Examples thereof include hydroxy acids such as acid, malic acid, glyceric acid and lactic acid, and amine salts of these carboxylic acids. These may use only 1 type and may use 2 or more types together.

Examples of the thixotropic property-imparting agent include polyolefin waxes such as castor wax (hardened castor oil); fatty acid amides such as m-xylylene bis stearamide; substituted urea waxes such as N-butyl-N′-stearyl urea; Examples thereof include polymer compounds such as polyethylene glycol, polyethylene oxide, methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose; inorganic particles such as silica particles and kaolin particles. These may use only 1 type and may use 2 or more types together.

In the flux of the present invention, a thixotropic agent can be contained. The amount of the thixotropy-imparting agent is not particularly limited. When the total amount of aromatic compounds is 100 parts by mass, 0.1 to 30 parts by mass can be used, preferably 0.1 to 20 parts by mass. More preferably, it is 0.1 to 10 parts by mass. The adhesive force between the constituent members can be adjusted by the content of the thixotropic agent.

Further, the properties of the flux of the present invention are not particularly limited, that is, for example, it may be a solid or a liquid (including a paste, the same shall apply hereinafter). Among these, the solid means a state in which it does not flow in an atmosphere of 1 atm and 23 ° C. regardless of whether or not an external force is applied.
Further, the liquid means a state in which it flows without applying an external force in an atmosphere of 1 atm and 23 ° C. In the case of a liquid flux, for example, the viscosity at 1 atmosphere and a temperature of 23 ° C. can be 0.001 to 1000 Pa · S. This viscosity can be further set to 0.01 to 800 Pa · S, and can be set to 0.1 to 700 Pa · S.

The flux of the present invention may be in any of the above states, and can be appropriately selected depending on the usage situation. For example, the solid flux can be used after being cut into pieces and placed on a target site. Further, the liquid flux can be attached to the target site by screen printing or the like, and can be further attached to the target site by coating.

In addition, the flux of this invention can exhibit adhesiveness as mentioned above by containing the said aromatic compound. This adhesion usually occurs when this flux is interposed between metals, but with a liquid flux, the adhesion tends to be exhibited in a shorter time. On the other hand, the solid flux tends to have a longer time until sufficient adhesiveness is obtained compared to the liquid flux. For this reason, when using a solid-state flux, it is preferable to heat. The heating temperature is preferably not higher than the vaporization temperature, and particularly preferably 20 to 100 ° C. lower than the vaporization temperature and 10 to 50 ° C. higher than the melting point.

[2] Conductive paste The conductive paste of the present invention contains the flux in the present invention and conductive metal particles.

The flux of the present invention described above can be applied as it is. The amount of the flux contained in the conductive paste of the present invention is not particularly limited, but the content of the flux is preferably 0.1 to 30% by mass when the conductive paste is 100% by mass. More preferably, the content is 1 to 20% by mass, and still more preferably 5 to 10% by mass. When the content of the flux is in the above range, a conductive paste having excellent substrate wettability can be obtained.

The conductive metal particles are not particularly limited as long as they are conductive metal particles used for bonding between metals, or fixing each member (electronic component, etc.) to a substrate in an electronic circuit or the like. A solder powder, a metal powder made of gold, silver, copper, aluminum, an alloy containing these metals, or the like can be used. Among these, solder powder is preferable when used for joining metals at low temperatures.

Examples of the solder powder include Sn—Pb, Sn—Pb—Ag, Sn—Pb—Bi, Sn—Pb—In, Sn—Pb—Sb, etc., as well as lead-free Sn—Sb alloys, Sn -Bi alloy, Sn-Ag alloy, Sn-Zn alloy (Ag, Cu, Bi, In, Ni, P, etc. may be added) and the like. These may use only 1 type and may use 2 or more types together.

The shape of the conductive metal particles may be either spherical or irregular. The particle diameter of the conductive metal particles may be a normal one. In the case of a spherical shape, the diameter is preferably 5 to 200 μm, more preferably 5 to 100 μm, and further preferably 5 to 50 μm.

Further, the content of the conductive metal particles is preferably 70 to 99.9% by mass, more preferably 80 to 99% by mass, and still more preferably when the entire conductive paste is 100% by mass. 90 to 95% by mass. When the content of the conductive metal particles is in the above range, a conductive paste having excellent substrate wettability can be obtained.

In addition, in the conductive paste of the present invention, as long as the object of the present invention is achieved, other additives can be contained in addition to the flux containing the aromatic compound and the conductive metal particles.

Examples of the method for producing the conductive paste of the present invention include a method of kneading the flux, the solder powder, and an additive added as necessary by a conventional method. Examples of the kneading machine include a vacuum stirring device, a kneading device, and a planetary mixer. The temperature and conditions at the time of blending are not particularly limited, but kneading at 5 to 25 ° C. is usually preferable.

[3] Joined component In the joined component of the present invention, a component member and another component member are bonded using the conductive paste of the present invention.

The above-mentioned constituent members and other constituent members are not particularly limited as long as they are members bonded by bonding. Examples of the members (constituent members and other constituent members) include various substrates such as a component mounting substrate and a chip mounting substrate, and various electronic components such as an electronic circuit module, a flip chip IC, and a semiconductor chip.

In the joining component of the present invention, the constituent members are joined together via a conductive metal derived from the conductive paste of the present invention.
As the joining component of the present invention, for example, a surface mounting type electronic substrate (hereinafter referred to as “mounting body”) shown in FIG. This mounting body will be described below as an example.
As shown in FIG. 1, in this mounting body,

external electrodes

5a and 5b of a multilayer ceramic capacitor 4 are provided on component connection conductors (hereinafter referred to as “lands”) 2a and 2b of a substrate 1 for component mounting. These are bonded via conductive bonding materials (solder or the like) 23a, 23b derived from the conductive paste of the present invention.

The manufacturing method of the said joining component (joining method at the time of using the electrically conductive paste of this invention) will not be specifically limited if it is a manufacturing method to which the said structural member is joined using the electrically conductive paste of this invention. For example, a normal manufacturing method including a conductive paste application process and a component mounting process in this order can be given. That is, the method for manufacturing a bonded part of the present invention is a method for manufacturing a bonded part in which a component member and another component member are bonded, and the conductive paste application for applying the conductive paste of the present invention to the component member. And a component mounting step of mounting other constituent members on the applied conductive paste.
The method for manufacturing a joined component of the present invention usually further includes a reflow step after the component mounting step. Moreover, as a preferable manufacturing method, a manufacturing method including a preheating step between the component mounting step and the reflow step can be cited.

That is, a method for manufacturing a joined part in which a constituent member and another constituent member are joined, the conductive paste applying step of applying the conductive paste of the present invention to the constituent member, and the applied conductive paste A component mounting step for mounting other constituent members, and a preheating step for preheating the constituent members mounted with the other constituent members without melting the conductive metal particles. And Furthermore, in the case of particles (for example, solder powder) in which the conductive metal particles can be melted, a reflow step of melting the conductive metal particles contained in the conductive paste can be provided as necessary.

The joining member manufacturing method of the present invention will be described below as an example.
(1) Conductive paste application process: Conducted on the

lands

2a and 2b on the substrate 1 (component) having the component connecting conductors (hereinafter referred to as “lands”) 2a and 2b shown in FIG. Printing

paste

3a, 3b is printed or applied [see FIG. 2 (b)].
(2) Component mounting step: After the step (1), the electronic component 4 (other components) including the

external electrodes

5a and 5b is mounted on the

conductive pastes

3a and 3b [FIG. )reference〕.
(3) Preheating step: After the step (2), the

conductive pastes

3a and 3b are printed or applied on the substrate 1 (component), and the electronic component 4 (other component) is mounted. Things are preheated. By this preliminary heating, the

conductive pastes

13a and 13b become viscous and exhibit more adhesive force (see FIG. 2D). The substrate 1 and the electronic component 4 are bonded by the

conductive pastes

13a and 13b having the adhesive force, and the electronic component 4 is held on the

conductive pastes

13a and 13b. And when mounting electronic components other than the above separately on the board | substrate 1, a conductive paste is newly apply | coated or printed and an electronic component is mounted on it. Since the electronic component mounted before the preheating is mounted on the conductive paste that has developed an adhesive force by the preheating, the substrate and the electronic component are bonded via the conductive paste. Therefore, a new electronic component can be mounted without causing a positional shift. Further, since the

conductive pastes

13a and 13b have adhesive strength, positioning between components mounted on the substrate 1 can be easily performed without melting the conductive metal particles.
(4) Reflow step: in the case where the conductive metal particles are meltable particles, the conductive particles contained in the

conductive pastes

13a and 13b are heated by passing through a reflow furnace or the like after the preliminary heating. Are melted and bonded. In other words, the constituent member and the other constituent member are joined by the conductive metal.

The heating temperature in the preheating step can be appropriately selected depending on the type of conductive metal particles, but is preferably 80 to 200 ° C, more preferably 100 to 180 ° C. When the heating temperature in the preheating step is within the above range, the conductive paste exhibits an adhesive force, and can bond the substrate and the electronic component. Further, the preheating step can be performed by a normal reflow furnace or the like.

The heating temperature in the reflow step can be appropriately selected depending on the type of conductive metal particles, but is preferably 200 to 350 ° C., more preferably 250 to 300 ° C. When the heating temperature in this reflow step is within the above range, the flux and the like contained in the conductive paste are volatilized and the flux residue hardly remains. Moreover, the conductive metal particles contained in the conductive paste can be melted to join the substrate and the electronic component.

Since the conductive paste of the present invention has an adhesive force, the substrate and the electronic component can be bonded without melting the conductive metal particles, and the number of reflows related to the manufacture of the bonded component can be reduced. it can. That is, for example, when a module board (other constituent member) to which an electronic component is joined (soldered or the like) is joined to a mother circuit board (constituent member), the electronic component is first joined to the module substrate. It is necessary to join the joined module board (other constituent member) to the mother circuit board (constituent member). In this case, the module substrate bonded to the mother circuit board is passed through the reflow furnace again when being bonded to the mother circuit board, and the module substrate is reflowed for the second time.

However, when the conductive paste of the present invention is used, first, an electronic component is bonded to the module substrate. Next, the module substrate to which the electronic component is bonded is bonded to the mother circuit substrate. Then, by passing the mother circuit board to which the module board is bonded to the reflow, all of the module board and the mother board can be joined. Thereby, the reflow which concerns on manufacture of joining components can be made only once.
That is, this method for manufacturing a joined part is a method for producing a joined part in which a constituent member and another constituent member are joined using the conductive paste of the present invention, and the first constituent member is electrically conductive. Conductive first paste applying step of applying paste, first component mounting step of mounting a second component on the applied conductive paste, and first of mounting the second component A first preheating step of preheating the component member without melting the conductive metal particles to bond the second component member and the first component member; and conducting to the third component member Conductive second paste application step of applying a conductive paste, and, if necessary, a second component mounting step of mounting a first component member having a second component member bonded onto the applied conductive paste And a third configuration in which the first component is mounted A second preheating step of preheating the material without melting the conductive metal particles to bond the first component and the third component; and, if necessary, a conductive metal In the case where the particles are meltable particles, a reflow step of melting the conductive metal particles contained in the conductive paste can be provided.

Excessive thermal stress on a joining component such as an electronic substrate may cause melting of conductive metal particles joined to the substrate, cracking of the substrate or joint due to thermal expansion, or the like. Melting or cracking of the conductive metal particles may cause problems such as short-circuit failure and reduction in bonding strength between the substrate and the electronic component.
Therefore, when the conductive paste of the present invention is used, bonding can be performed without applying excessive thermal stress, and a highly reliable bonded component can be provided.

Since the joined part of the present invention is joined using the conductive paste of the present invention, the flux residue is hardly left after joining, and it is not necessary to clean the joined part after joining. Furthermore, since excessive thermal stress can be reduced in the joining, a joining component with high joining reliability can be obtained.

Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not restrict | limited at all by these Examples. Further, “parts” in the examples are based on mass unless otherwise specified. Moreover, the measurement of the viscosity (Pa * s) in an Example and a comparative example was performed by the following method.
[viscosity]
It was measured with an E-type viscometer RE-105H manufactured by Toki Sangyo Co., Ltd.

[1] Preparation of solid flux <Examples 1 to 4>
In Table 1, the aromatic compounds shown in Examples 1 to 4 were used as solid flux.

[2] Preparation of liquid flux <Examples 5 and 6>
In Table 1, the aromatic compounds shown in Examples 5 and 6 were mixed, and the mixture was heated to 100 ° C. and stirred until it became liquid, thereby obtaining a liquid flux. The liquid flux was liquid at room temperature under atmospheric pressure and was not recrystallized even when cooled to 5 ° C. Table 1 also shows the viscosity (Pa · s) of this liquid flux under an atmosphere of 1 atm and 23 ° C.

<Comparative Example 1>
In Table 1, the compound shown in Comparative Example 1 and the solvent were mixed, and the mixture was heated to 100 ° C. and stirred until it became liquid, thereby obtaining a liquid flux. The liquid flux was liquid at room temperature under atmospheric pressure and was not recrystallized even when cooled to 5 ° C. Table 1 also shows the viscosity (Pa · s) of this liquid flux under an atmosphere of 1 atm and 23 ° C.

[3] Evaluation of Flux The following evaluations were performed on the fluxes obtained in Examples 1 to 6 and Comparative Example 1. The results are shown in Table 2.
(Production of oxide film (copper oxide) substrate)
A copper substrate was prepared by depositing copper in a thickness of 10 μm on a silicon wafer (thickness 1 mm, diameter 20 cm). Thereafter, the copper substrate was placed on a hot plate at 200 ° C. for 6 hours under air at 1 atm and heated to obtain an oxide film (copper oxide) substrate in which one side was completely oxidized.
(Production of oxide film (tin oxide) substrate)
A tin substrate was prepared by depositing tin with a thickness of 10 μm on a silicon wafer (thickness 1 mm, diameter 20 cm). Thereafter, the tin substrate was placed on a hot plate at 1 ° C. under air at 200 ° C. for 6 hours and heated to obtain an oxide film (tin oxide) substrate having one surface completely oxidized.

(1) Evaluation of Adhesiveness of Solid Flux (Examples 1 to 4) by Oxide Film (Copper Oxide) Substrate 0.5 g of solid flux was sampled and placed on the oxide film (copper oxide) substrate (oxide film) (Formation surface) was sprayed evenly and heated on a hot plate until the solid flux became liquid. Then, after the flux spread on the substrate is melted, another oxide film substrate of the same type is overlapped so that the oxide film forming surface is in contact with the molten flux, and the two oxide film substrates are stacked. The oxide film forming surface was adhered without a gap through the melted flux. The two oxide film substrates after adhesion were cooled to room temperature, and whether or not the oxide film (copper oxide) substrate was firmly adhered was visually evaluated. The case where it was firmly bonded was evaluated as “◯”, and the case where it was not firmly bonded was evaluated as “x”.

(2) Evaluation of Adhesiveness of Solid Flux (Examples 1 to 4) by Oxide Film (Tin Oxide) Substrate 0.5 g of solid flux was sampled and formed on the oxide film (tin oxide) substrate (oxide film formation) And uniformly heated on a hot plate until the solid flux becomes liquid. Then, after the flux spread on the substrate is melted, another oxide film substrate of the same type is overlapped so that the oxide film forming surface is in contact with the molten flux, and the two oxide film substrates are stacked. The oxide film forming surface was adhered without a gap through the melted flux. The two oxide film substrates after adhesion were cooled to room temperature, and whether or not the oxide film (tin oxide) substrate was firmly adhered was visually evaluated. The case where it was firmly bonded was evaluated as “◯”, and the case where it was not firmly bonded was evaluated as “x”.

(3) Evaluation of Adhesiveness of Liquid Flux (Examples 5 and 6 and Comparative Example 1) by Oxide Film (Copper Oxide) Substrate Liquid Flux is Applied on the Oxide Film (Copper Oxide) Substrate (Oxide Film Formation) And the other oxide film substrate of the same type is overlapped so that the oxide film formation surface is in contact with the liquid flux, and the oxide film formation surfaces of the two oxide film substrates are stacked. It was made to adhere without a gap through a liquid flux. After 24 hours, it was visually evaluated whether or not the oxide film (copper oxide) substrate was firmly adhered. The case where it was firmly bonded was evaluated as “◯”, and the case where it was not firmly bonded was evaluated as “x”.

(4) Adhesive Evaluation of Liquid Flux (Examples 5 and 6 and Comparative Example 1) by Oxide Film (Tin Oxide) Substrate Liquid Form Flux on Oxide Film (Tin Oxide) Substrate (Oxide Film Formation) And the other oxide film substrate of the same type is overlapped so that the oxide film formation surface is in contact with the liquid flux, and the oxide film formation surfaces of the two oxide film substrates are stacked. It was made to adhere without a gap through a liquid flux. After 24 hours, whether or not the oxide film (tin oxide) substrate was firmly adhered was visually evaluated. The case where it was firmly bonded was evaluated as “◯”, and the case where it was not firmly bonded was evaluated as “x”.

(5) Reducibility evaluation of flux oxide film Each substrate after the adhesion evaluation was heated on a hot plate. This substrate has two oxide film substrates that are attached and stacked via a solid flux or a liquid flux. And the temperature at which a reducing action was expressed was measured. When the oxide film is copper oxide, the temperature at which this reduction action appears was the temperature at which the color of the oxide film changed from black to red gold. When the oxide film was tin oxide, the temperature was such that the color of the oxide film changed from purple black to white.

(6) Flux residue evaluation Each substrate after the adhesion evaluation was placed on a hot plate in a nitrogen atmosphere and heated at 250 ° C., which is equivalent to the solder melting temperature, for 120 minutes. This substrate has two oxide film substrates that are attached and stacked via a solid flux or a liquid flux. And the presence or absence of the residue in the oxide film substrate surface after a heating was evaluated. Evaluation of the residue was made by visually observing the heated oxide film substrate, and when no stain or burn was observed, it was evaluated as “◯” as no residue. Moreover, the case where a spot and a burn were observed was evaluated as "x" as there was a residue.

From the results shown in Table 2, the flux composition of the present invention is not only excellent in reducing ability to metal oxides, but also excellent in substrate adhesion and does not generate any residue that adversely affects wiring insulation. It has excellent characteristics not found in the flux composition.

Claims

An aromatic compound having two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring or having two phenolic hydroxyl groups at two positions of the position number of one jump of the aromatic ring Containing flux,
The flux characterized by the melting point of the aromatic compound under 1 atm being 23 ° C. or higher.
The flux according to claim 1, wherein the vaporization temperature of the aromatic compound is 100 ° C or higher under 1 atm.
An aromatic compound having two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring is a compound represented by the following general formula (1), and
The aromatic compound which has two phenolic hydroxyl groups in two positions of the position number of one jump of the aromatic ring is a compound represented by the following general formula (2). flux.

[In the general formulas (1) and (2), R represents an alkyl group, and n represents an integer of 0 to 4. ]
An aromatic compound having two phenolic hydroxyl groups at two positions of adjacent position numbers of the aromatic ring is a compound represented by the following general formula (3) or the following general formula (4), and
The aromatic compound which has two phenolic hydroxyl groups in two positions of the position number of one jump of the aromatic ring is a compound represented by the following general formula (5). flux.

[In the general formulas (3) to (5), R represents an alkyl group, and n represents an integer of 0 to 4. ]
The flux according to any one of claims 1 to 4, wherein the aromatic compound contains two or more kinds of compounds.
The flux according to any one of claims 1 to 5, which is solid under an atmosphere of 1 atm and 23 ° C.
7. A conductive paste comprising the flux according to any one of claims 1 to 6 and conductive metal particles.
A joining component, wherein the constituent member and another constituent member are joined using the conductive paste according to claim 7.
A method of manufacturing a joined part in which a constituent member and another constituent member are joined,
A conductive paste application step of applying the conductive paste according to claim 7 to the constituent members;
A component mounting process for mounting other components on the applied conductive paste;
A method for manufacturing a joined part, comprising: