JP6991104B2 - Joining material and joining method using it - Google Patents

Description

The present invention relates to a joining material and a joining method using the same, and more particularly to a joining material containing a copper compound and a joining method using the same.

Most semiconductor devices have a structure in which a semiconductor element is bonded on a circuit layer made of a metal member. When joining electronic components such as semiconductor elements onto a circuit layer, a method using a solder material is widely used. However, due to the improved heat resistance of the semiconductor elements themselves, the semiconductor device can be used in the engine room of an automobile. It is often used in high temperature environments such as, and heat resistance is required for the bonding material. However, when an electronic component such as a semiconductor element and a circuit layer are bonded using a solder material, if this is used in a high temperature environment, a part of the solder melts and the electronic component such as a semiconductor element and a circuit. The problem is that the bonding reliability with the layer is reduced.

Therefore, as an alternative to the solder material, a technique for joining electronic components such as semiconductor elements to a circuit layer using silver, copper, or the like, which has heat resistance, high thermal conductivity, and conductivity, has been proposed. For example, Japanese Patent Application Laid-Open No. 2008-208442 (Patent Document 1) describes a bonding method using a bonding material containing metal compound particles such as copper oxide and a reducing agent such as ethylene glycol. In this bonding method, an oxide layer is formed at the bonding interface of the bonded layer in order to efficiently remove organic substances such as reducing agents in the bonding layer. Since it is necessary to expose the member to high-temperature steam or immerse it in an alkaline solution, there is a problem of causing damage or deterioration of electronic parts such as semiconductor elements.

Japanese Unexamined Patent Publication No. 2008-208442

The present invention has been made in view of the above-mentioned problems of the prior art, and it is not necessary to form an oxide layer on the member to be joined, and the joining temperature is lower (for example, 400 ° C. or lower, preferably 350 ° C. or lower). It is an object of the present invention to provide a bonding material capable of obtaining high bonding strength even at a temperature of 300 ° C. or lower, and a bonding method using the bonding material.

As a result of diligent research to achieve the above object, the present inventors use a bonding material containing a copper salt of a hydroxycarboxylic acid having 1 to 6 carbon atoms and an alcohol having 3 to 12 hydroxy groups for bonding. As a result, it is not necessary to form an oxide layer on the member to be joined, and high bonding strength can be obtained even at a lower bonding temperature (for example, 400 ° C or lower, preferably 350 ° C or lower, more preferably 300 ° C or lower). We have found and completed the present invention.

That is, the bonding material of the present invention is characterized by containing a copper salt of a hydroxycarboxylic acid having 1 to 6 carbon atoms and an alcohol having 3 to 12 hydroxy groups. In such a bonding material, the hydroxycarboxylic acid preferably has 2 to 4 carbon atoms.

The joining method of the present invention comprises a step of forming a joining material layer between a bonded surface of a metal member and a bonded surface of a non-bonded member using the bonding material according to claim 1 or 2, and the bonding. A method comprising a step of heating a material layer to sinter the bonding material to form a bonding layer, and bonding the metal member and the non-bonding member via the bonding layer. be.

It should be noted that the reason why high bonding strength can be obtained even at a lower bonding temperature (for example, 400 ° C. or lower, preferably 350 ° C. or lower, more preferably 300 ° C. or lower) by bonding using the bonding material of the present invention is not always clear. However, the present inventors infer as follows. That is, the bonding material of the present invention contains a copper salt of a hydroxycarboxylic acid having 1 to 6 carbon atoms and an alcohol having 3 to 12 hydroxy groups. The copper salt of the hydroxycarboxylic acid is decomposed at a low temperature by a self-reduction mechanism to produce metallic copper. At this time, if an alcohol having 3 to 12 hydroxy groups is present in the reaction system, the mixing of oxygen when the copper salt of the hydroxycarboxylic acid is decomposed is prevented. As a result, even if the bonding material of the present invention is fired in the atmosphere, the formation of copper oxide is suppressed, so that a bonding layer containing no copper oxide is formed. Further, since the alcohol having 3 to 12 hydroxy groups is decomposed and volatilized at the decomposition temperature of the hydroxycarboxylate copper, it is sufficiently removed to form a bonding layer without forming an oxide layer on the member to be bonded. Hard to remain. As described above, the bonding layer formed by using the bonding material of the present invention is made of metallic copper and does not contain copper oxide or organic components, so that it is presumed to have high bonding strength.

According to the present invention, it is not necessary to form an oxide layer on the member to be bonded, and the bonding is performed with high bonding strength even at a lower bonding temperature (for example, 400 ° C or lower, preferably 350 ° C or lower, more preferably 300 ° C or lower). It becomes possible to do.

It is a schematic diagram which shows the test piece used in the joint strength measurement.

Hereinafter, the present invention will be described in detail according to the preferred embodiment thereof.

[Joining material]
First, the bonding material of the present invention will be described. The bonding material of the present invention contains a copper salt of a hydroxycarboxylic acid having 1 to 6 carbon atoms and an alcohol having 3 to 12 hydroxy groups.

(Copper salt of hydroxycarboxylic acid)
The copper salt of hydroxycarboxylic acid used in the present invention is a copper salt of hydroxycarboxylic acid having 1 to 6 carbon atoms (hereinafter, also simply referred to as "copper salt of hydroxycarboxylic acid"). When the number of carbon atoms of the hydroxycarboxylic acid exceeds the upper limit, the proportion of metallic copper particles produced by the self-reducing mechanism becomes small, so that the bonding strength decreases. In the bonding material of the present invention, the copper salt of the hydroxycarboxylic acid is decomposed by heating to form metallic copper, whereby a bonding layer having high bonding strength can be formed.

Examples of the copper salt of such a hydroxycarboxylic acid include copper hydrogencarbonate (the number of carbon atoms of the hydroxycarboxylic acid: 1); copper glycolate (the number of carbon atoms of the hydroxycarboxylic acid: 2); copper hydroxypropionate (for example, lactic acid). Copper), copper glycerate (above, carbon number of hydroxycarboxylic acid: 3); copper hydroxybutyrate, copper methyl lactate, copper hydroxycyclopropanecarboxylate, copper malate, copper tartrate (above, carbon number of hydroxycarboxylic acid: 4); Copper hydroxyvalerate, hydroxyisovaleric acid, copper dimethylol propionate, copper hydroxypivalate (above, carbon number of hydroxycarboxylic acid: 5); copper hydroxyhexanate, copper dimethylol butyrate, copper gluconate ( As mentioned above, the number of carbon atoms of the hydroxycarboxylic acid: 6) can be mentioned. Such a copper salt of hydroxycarboxylic acid may be used alone or in combination of two or more.

Further, among these copper salts of hydroxycarboxylic acids, the heat generation in the self-reduction reaction is mild, it is easy to form a uniform bonding surface, and the proportion of metallic copper particles is large, so that high bonding strength can be obtained. Therefore, a copper salt of a hydroxycarboxylic acid having 2 to 4 carbon atoms is preferable, and a copper salt of a hydroxycarboxylic acid having 2 to 3 carbon atoms is more preferable.

In the bonding material of the present invention, the content of such a copper salt of hydroxycarboxylic acid is not particularly limited, but the copper salt of hydroxycarboxylic acid is easily uniformly dispersed in the bonding material, and high bonding strength can be obtained. From this viewpoint, 5 to 80% by mass is preferable, 10 to 65% by mass is more preferable, and 15 to 50% by mass is further preferable with respect to the entire bonding material.

(alcohol)
The alcohol used in the present invention is an alcohol having 3 to 12 hydroxy groups (hereinafter, also simply referred to as “polyhydric alcohol”). The alcohol having such a hydroxy group has a thermogravimetric reduction temperature (150 to 300 ° C.) near the decomposition temperature of the copper salt of the hydroxycarboxylic acid, and is decomposed and removed at the time of firing (during joining). Therefore, it does not easily remain in the bonding layer. On the other hand, if the hydroxy group is less than the above lower limit, a non-oxidizing atmosphere cannot be formed at the time of firing (at the time of bonding), so that the bonding strength is lowered. On the other hand, if the hydroxy group exceeds the upper limit, it tends to remain as an organic component even after firing, so that the bonding strength is lowered. In the bonding material of the present invention, this polyhydric alcohol can form a bonding layer having high bonding strength in order to prevent the mixing of oxygen into the metallic copper produced by the decomposition of the copper salt of hydroxycarboxylic acid. can.

The polyhydric alcohol is an alcohol represented by the formula: R (OH) _n [n is an integer of 3 to 12], and the carbon chain R may be linear or branched, and may be cyclic. May be. Examples of the linear polyhydric alcohol include glycerin and butanetriol (above, hydroxy group number: 3); erythritol, threitol, diglycerin (above, hydroxy group number: 4); arabitol, xylitol, ribitol and triglycerin (above, hydroxy group number: 4). As described above, the number of hydroxy groups: 5); igitol, galactitol, sorbitol, mannitol (above, number of hydroxy groups: 6); volemitol, persetol (above, number of hydroxy groups: 7) can be mentioned. Examples of the branched polyhydric alcohol include trimethylolethane, trimethylolpropane (above, number of hydroxy groups: 3); pentaerythritol (number of hydroxy groups: 4); and dipentaerythritol (number of hydroxy groups: 6). .. Further, examples of the cyclic polyhydric alcohol include cyclohexanetriol (hydroxy group number: 3); quercitol, glucose, galactose, fructose (above, hydroxy group number: 5); inositol (hydroxy group number: 6) sucrose, lactose, maltose, and the like. Trehalose (above, number of hydroxy groups: 8); maltotriose (number of hydroxy groups: 11) can be mentioned. Such a multivalent alcohol may be used alone or in combination of two or more.

Further, among these polyhydric alcohols, an alcohol having 3 to 8 hydroxy groups is preferable, and an alcohol having 3 to 4 hydroxy groups is preferable from the viewpoint that a non-oxidizing atmosphere can be efficiently formed and high bonding strength can be obtained. Is more preferable. Further, from the viewpoint that it is easily decomposed and removed during firing (during joining) and is unlikely to remain in the joining layer, the thermogravimetric reduction rate of the polyhydric alcohol by heating to 300 ° C. is preferably 70 to 100%, and is 85. ~ 100% is more preferable.

In the bonding material of the present invention, the content of such a polyhydric alcohol is not particularly limited, but high bonding strength can be prevented because oxygen in the atmosphere can be prevented from being mixed and a non-oxidizing atmosphere can be efficiently formed. From the viewpoint of obtaining the above, 1 to 95% by mass is preferable, 10 to 75% by mass is more preferable, and 20 to 55% by mass is further preferable with respect to the entire bonding material.

(solvent)
When the bonding material of the present invention is used as a paste, a solvent may be added to the copper salt of the hydroxycarboxylic acid and the polyhydric alcohol. Examples of such a solvent include water, alcohol (including glycol), ketone, ether (including glycol ether), ester (including cyclic ester), polar alicyclic hydrocarbon, amide, sulfoxide and the like.

Examples of water include ion-exchanged water and distilled water. Examples of the alcohol include isopropyl alcohol, isobutyl alcohol, 3-methoxy-3-methyl-1-butanol, 1-octanol, terpineol, cyclohexanol, ethylene glycol, propylene glycol and the like. Examples of the ketone include isophorone and diisobutyl ketone. Examples of the ether include propylene glycol monomethyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether. Examples of the ester include methyl acetate, propyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monobutyl ether acetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 2-butoxyethyl acetate and the like. Can be mentioned. Examples of the polar alicyclic hydrocarbon include N-methyl-2-pyrrolidone and propylene carbonate. Examples of the amide include N, N-dimethylformamide and the like. Examples of sulfoxide include dimethyl sulfoxide and the like. These solvents may be used alone or in combination of two or more.

Further, among such solvents, a solvent having a boiling point of 350 ° C. or lower is preferable, and a solvent having a boiling point of 300 ° C. or lower is more preferable, from the viewpoint of obtaining high bonding strength because it is difficult to remain in the bonding layer after firing.

In the bonding material of the present invention, the content of such a solvent is not particularly limited, but is preferably 0 to 94% by mass with respect to the entire bonding material paste.

(Dispersant)
In the bonding material of the present invention, a dispersant may be added in order to improve the dispersibility of the copper salt of the hydroxycarboxylic acid. As such a dispersant, a dispersant that has little residue during firing (bonding) and does not easily affect the performance (bonding strength) of the bonding material is preferable. For example, the heat weight reduction rate by heating to 300 ° C. is 70. Anionic surfactants, cationic surfactants, nonionic surfactants and chelating agents, which are ~ 100% (more preferably 85-100%), are preferable.

As anionic surfactants, soap, alkylbenzene sulfonate, higher alcohol sulfate ester salt, polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid ester, α-olefin sulfonate, alkane sulfonate, monoalkyl phosphate. Examples include ester salts. Examples of the cationic surfactant include an alkyltrimethylammonium salt, a dialkyldimethylammonium salt, an alkyldimethylbenzylammonium salt and the like. Nonionic surfactants include higher alcohol alkylene oxide adducts, alkylphenol alkylene oxide adducts, fatty acid alkylene oxide adducts, polyhydric alcohol fatty acid ester alkylene oxide adducts, higher alkylamine alkylene oxide adducts, and fatty acid amide alkylene oxide adducts. , Polyalkylene glycol type nonionic surfactant such as alkylene oxide adduct of polyoxypropylene; Polyhydric alcohol type nonionic surfactant such as glycerol fatty acid ester, pentaerythritol fatty acid ester, sorbitol fatty acid ester, sucrose fatty acid ester can be mentioned. .. The higher alcohol is usually a linear or branched higher alcohol having a saturated or unsaturated total carbon number of 8 to 22, and the alkylphenol is usually a linear or branched, saturated or saturated. Unsaturated alkylphenols with a total carbon number of 7 to 22, fatty acids are usually saturated or unsaturated fatty acids with a total carbon number of 10 to 22, and polyhydric alcohols are usually saturated or unsaturated with a total carbon number of 3 to 22. Twelve polyhydric alcohols, the higher alkylamines are usually linear or branched, saturated or unsaturated higher alkylamines with a total carbon number of 8-22. Examples of the chelating agent include citric acid and ethylenediaminetetraacetic acid. These dispersants may be used alone or in combination of two or more.

In the bonding material of the present invention, the content of such a dispersant is preferably 0.01 to 40% by mass, preferably 0.01 to 10% by mass, based on the entire bonding material from the viewpoint of handleability of the bonding material. % Is more preferable.

(Other additives)
In the bonding material of the present invention, a binder and a flux may be blended in order to improve the coatability and promote the bonding. From the viewpoint of bonding strength, these binders and fluxes preferably have a thermogravimetric reduction rate of 70 to 100% (more preferably 85 to 100%) when heated to 300 ° C. Further, a metal component may be added in order to promote joining.

The binder may be either an organic binder or an inorganic binder. Further, the organic binder may have a viscosity adjusting function. Examples of the organic binder include water-soluble resins and water-based resins. Specifically, various modified polyester resins (for example, polyester resin, urethane modified polyester resin, epoxy modified polyester resin, acrylic modified polyester resin), polyether urethane resin, polycarbonate urethane resin, acrylic urethane resin, vinyl chloride and vinyl acetate are all used. Polymers, epoxy resins, phenolic resins, phenoxy resins, acrylic resins, maleic acid resins, fumaric acid resins, polyvinyl butyral resins, polyamideimides, polyimides, polyamides, modified celluloses (eg, nitrocellulose, cellulose acetate butyrate (CAB)) ), Cellulose acetate propionate (CAP)), vinyl resin (eg vinyl acetate, polyvinylidene fluoride), fluororesin, silicone resin, cellulose resin (eg ethyl cellulose, nitrocellulose), DAP resin (diallyl phthalate resin) , Polyolefin resin, synthetic rubber latex, polyvinyl alcohol, polyvinylpyrrolidone, paraffin and the like. Examples of the inorganic binder include silica sol, alumina sol, zirconia sol, titania sol and the like. These binders may be used alone or in combination of two or more.

Examples of the flux include monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, benzoic acid and avietic acid; succinic acid, malonic acid, glutaric acid, adipic acid, sebacic acid and decane. Dicarboxylic acids such as diacids and dodecanedioic acids; hydroxycarboxylic acids such as glycolic acid, lactic acid, DL-glyceric acid, DL-2-hydroxybutyric acid, DL-3-hydroxybutyric acid, 2-hydroxy-n-octanoic acid and the like. Can be mentioned. These fluxes may be used alone or in combination of two or more.

The metal component is not particularly limited in its constituent components, particle size and the like, and can be appropriately selected depending on the intended use. Further, the metal particles may contain impurities such as oxygen and dissimilar metals that are unavoidable in the manufacturing method, and oxygen, metal oxides and mercaptocarboxylic acids may be contained in advance as necessary to prevent rapid oxidation of the metal particles. Other organic compounds may be contained.

As the metal component, metals of Group VIII (iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum) and Group IB (copper, silver, gold) are preferable from the viewpoint of conductivity. Such a metal component may be one kind of metal or two or more kinds of metals (for example, an alloy or a laminate).

In the bonding material of the present invention, the content of such an additive is preferably 0.01 to 40% by mass, preferably 0.01 to 10% by mass, based on the entire bonding material from the viewpoint of handleability of the bonding material. % Is more preferable.

(Production method)
The bonding material of the present invention can be produced, for example, by stirring and mixing the copper salt of the hydroxycarboxylic acid, the polyhydric alcohol, and if necessary, a solvent or the like. The mixer used for such stirring and mixing is not particularly limited, and for example, a mixer such as a homomixer, an agitator, a disper, a planetary mixer, an ajihomo mixer, a universal mixer, an attritor, a rotation / revolution type mixer, or the like. Can be appropriately selected and used. These mixers may be used alone or in combination of two or more.

<Joining method>
Next, the joining method of the present invention will be described. The bonding method of the present invention comprises a step of forming a bonding material layer between a bonded surface of a metal member and a bonded surface of a metal member using the bonding material of the present invention, and heating the bonding material layer. This is a method including a step of sintering the bonding material to form a bonding layer, and bonding the metal member and the bonded member via the bonding layer.

The metal member is not particularly limited as long as it is a conductive metal member, and examples thereof include circuit layers such as electrodes and wiring of electronic parts such as semiconductor devices. The type of metal constituting the metal member is not particularly limited, and examples thereof include gold, silver, copper, and nickel. Further, the member to be joined is not particularly limited as long as it is an electronic member, and examples thereof include a semiconductor element and the like.

In such a joining method of the present invention, the arrangement state of the joining material layer formed between the joined surface of the metal member and the joined surface of the joined member is, for example,
(1) A state in which the bonding material layer is arranged only between the bonded surface of the metal member and the bonded surface of the bonded member.
(2) A state in which the bonding material layer is arranged only on the outer edges of both the bonded surfaces of the metal member and the bonded surface of the bonded member.
(3) A state in which the bonding material layer is arranged between the bonded surface of the metal member and the bonded surface of the bonded member and at the outer edges of both bonded surfaces.
And so on.

In the joining method of the present invention, as a method of forming the joining material layer, for example, a necessary portion (for example, a connection portion of an electronic component) of a metal member (for example, an electrode on a substrate) and / or a member to be joined (for example, a connection portion of an electronic component) is used. A method of applying, adhering, injecting, coating or filling a paste-like bonding material from a fine nozzle into a region forming a bonding material layer) by an inkjet method; an open metal mask or mesh. A method of applying, adhering, injecting, coating or filling the joining material using a mask; a method of applying, adhering, injecting, coating or filling the joining material using a dispenser and the like can be mentioned. These methods can be appropriately selected or combined according to the area, shape, and the like of the metal member to be joined (for example, the electrode on the substrate) and the member to be joined (for example, the connection portion of the electronic component).

The arrangement amount of the bonding material (size of the bonding material layer, etc.) in the bonding method of the present invention is determined by the metal member to be bonded (for example, the electrode on the substrate) and the member to be bonded (for example, the connection portion of the electronic component). It can be appropriately set according to the area, joint strength, etc., and is not particularly limited.

Further, in the bonding method of the present invention, the heating temperature (firing temperature) at which the bonding material is sintered is not particularly limited as long as the bonding material is melted and sintered, but the hydroxycarboxylic acid can be used. The decomposition temperature of the copper salt is preferably 235 ° C or higher and 400 ° C or lower, more preferably 250 ° C or higher and 400 ° C or lower, and further preferably 250 ° C or higher and 350 ° C or lower from the viewpoint of reactivity. .. When the heating temperature exceeds the upper limit, the member to be joined such as an electronic component tends to be easily damaged (for example, melting, deformation, etc.) by heat.

Further, in the joining method of the present invention, the pressure for sintering the joining material may be no pressure as long as the pressure at which the metal member and the member to be joined are joined, but the joining is promoted. From this point of view, pressurization may be performed. As the pressure at the time of such joining, for example, 0 to 20 MPa is preferable, 0 to 15 MPa is more preferable, and 0 to 10 MPa is further preferable, and 0 to 10 MPa is more preferable from the viewpoint of suppressing damage to the member to be joined such as an electronic component. 1 MPa is particularly preferable.

Further, in the joining method of the present invention, the heating time (firing time) when sintering the joining material is not particularly limited as long as the joining material is sufficiently melted and sintered, but is 1 to 120. Minutes are preferred, 30-90 minutes are more preferred, and 60-90 minutes are even more preferred.

Further, in the bonding method of the present invention, the atmosphere when forming or heating the bonding material layer is not particularly limited, and is, for example, an air atmosphere, an inert gas (for example, nitrogen, argon) atmosphere, or a reduction. Any atmosphere such as an atmosphere (for example, a hydrogen gas atmosphere) may be used.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. The thermogravimetric reduction temperature and the thermogravimetric reduction rate of alcohol and the like used in Examples and Comparative Examples were measured by the following methods.

<Thermogravimetric analysis>
Using a thermogravimetric analyzer (“TG-DTA8122” manufactured by Rigaku Co., Ltd.), a TG curve was obtained at a temperature rise rate of 10 ° C./min in the atmosphere, and the extrapolated temperature of the thermal weight decrease in the obtained TG curve ( The temperature at which the thermogravimetric analysis was reduced was defined as the intersection of the two tangents when the tangent line before the start of thermogravimetric reduction and the tangent line at the inversion point after the start of thermogravimetric analysis were taken. Further, based on the obtained TG curve, the mass at 50 ° C. and 300 ° C. was obtained, and the following formula:
Thermogravimetric reduction rate (%) = {1- (mass at 300 ° C) / (mass at 50 ° C)} x 100
The thermogravimetric reduction rate was calculated.

(Example 1)
37 parts by mass of copper lactate (number of carbon atoms of hydroxycarboxylic acid: 3), 33 parts by mass of pentaerythritol (number of hydroxy groups: 4, heat weight reduction temperature: 249 ° C., heat weight reduction rate: 90%) and 30 parts by mass of terpineol. The mixture was further mixed, and further stirred at 2000 rpm for 3 minutes using a rotation / revolution type mixer (“SR-500” manufactured by Shinky Co., Ltd.) to prepare a bonding material paste.

25 mg of this bonding material paste was applied to the surface of the copper plate A (length 50 mm, width 10 mm, thickness 1.6 mm) in a region of length 10 mm and width 10 mm using a mask. After application, the mask was removed and pre-dried at 60 ° C. for 30 minutes. On the paste film of the copper plate A after pre-drying, a copper plate B (length 50 mm, width 10 mm, thickness 1.6 mm) in which the paste film was produced in the same manner as the copper plate A was placed so that the paste films were in contact with each other. In an air atmosphere, under the temperature condition of 260 ° C., the copper plate A and the copper plate are fired from the upper part of the copper plate B at a pressure of 0.5 MPa for 90 minutes while being pressed for 90 minutes through the bonding layer (length 10 mm, width 10 mm). B was joined to prepare a test piece for measuring the joining strength shown in FIG. Three pieces of this test piece were prepared. As the copper plate A and the copper plate B, those which had been degreased with acetone in advance and then washed with distilled water were used.

(Example 2)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper glycolate (the number of carbon atoms of the hydroxycarboxylic acid: 2) was used instead of copper lactate. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 3)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper malate (carbon number of hydroxycarboxylic acid: 4) was used instead of copper lactate. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 4)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper tartrate (carbon number of hydroxycarboxylic acid: 4) was used instead of copper lactate. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 5)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of diglycerin (hydroxy group number: 4, thermogravimetric reduction temperature: 257 ° C., thermogravimetric reduction rate: 98%) was used instead of pentaerythritol. .. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 6)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of glycerin (hydroxy group number: 3, thermogravimetric reduction temperature: 193 ° C., thermogravimetric reduction rate: 100%) was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 7)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of trimethylolpropane (hydroxy group number: 3, thermogravimetric reduction temperature: 194 ° C., thermogravimetric reduction rate: 100%) was used instead of pentaerythritol. did. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 8)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of xylitol (hydroxy group number: 5, thermogravimetric reduction temperature: 269 ° C., thermogravimetric reduction rate: 63%) was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 9)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of lactose (hydroxy group number: 8, thermogravimetric reduction temperature: 226 ° C., thermogravimetric reduction rate: 48%) was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 10)
A bonding material paste was prepared in the same manner as in Example 1 except that the amount of copper lactate was changed to 52 parts by mass and the amount of pentaerythritol was changed to 18 parts by mass. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 11)
A bonding material paste was prepared in the same manner as in Example 1 except that the amount of copper lactate was changed to 35 parts by mass and the amount of pentaerythritol was changed to 35 parts by mass. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 12)
A bonding material paste was prepared in the same manner as in Example 1 except that the amount of copper lactate was changed to 18 parts by mass and the amount of pentaerythritol was changed to 52 parts by mass. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Example 13)
25 mg of the bonding material paste prepared in the same manner as in Example 1 was applied to the surface of the copper plate A (length 50 mm, width 10 mm, thickness 1.6 mm) in a region of length 10 mm and width 10 mm using a mask. After coating, the mask is removed, and the paste film B (length 50 mm, width 10 mm, thickness 1.6 mm) in which the paste film is produced in the same manner as the copper plate A is placed on the paste film of the copper plate A so that the paste films are in contact with each other. After the arrangement, the copper plate A and the copper plate B were joined by firing in an air atmosphere under a temperature condition of 260 ° C. for 90 minutes without applying pressure to prepare a test piece for measuring the joining strength. Three pieces of this test piece were prepared. As the copper plate A and the copper plate B, those which had been degreased with acetone in advance and then washed with distilled water were used.

(Example 14)
A test piece for measuring joint strength was prepared by joining the copper plate A and the copper plate B in the same manner as in Example 1 except that the applied pressure at the time of joining was changed to 1 MPa.

(Example 15)
A test piece for measuring joint strength was prepared by joining copper plate A and copper plate B in the same manner as in Example 1 except that the firing temperature at the time of joining was changed to 245 ° C.

(Example 16)
A test piece for measuring joint strength was prepared by joining copper plate A and copper plate B in the same manner as in Example 1 except that the firing temperature at the time of bonding was changed to 275 ° C. and the firing time was changed to 60 minutes.

(Example 17)
A test piece for measuring joint strength was prepared by joining copper plate A and copper plate B in the same manner as in Example 1 except that the firing temperature at the time of bonding was changed to 290 ° C. and the firing time was changed to 30 minutes.

(Comparative Example 1)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of 2-hydroxy-n-copper octanate (the number of carbon atoms of the hydroxycarboxylic acid: 8) was used instead of copper lactate. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 2)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper acetate was used instead of copper lactate. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 3)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper formate was used instead of copper lactate. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 4)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper caprylate was used instead of copper lactate. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 5)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of terpineol (hydroxy group number: 1, thermogravimetric reduction temperature: 92 ° C., thermogravimetric reduction rate: 100%) was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 6)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of decanol (hydroxy group number: 1, thermogravimetric reduction temperature: 125 ° C., thermogravimetric reduction rate: 100%) was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 7)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of diethylene glycol (hydroxy group number: 2, thermogravimetric reduction temperature: 142 ° C., thermogravimetric reduction rate: 100%) was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 8)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of acetic acid was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 9)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of formic acid was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 10)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of lactic acid was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 11)
A bonding material paste was prepared in the same manner as in Example 1 except that 33 parts by mass of hydrochloric acid was used instead of pentaerythritol. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 12)
A bonding material paste was prepared in the same manner as in Example 1 except that the amount of copper lactate was changed to 55 parts by mass and the amount of terpineol was changed to 45 parts by mass, and pentaerythritol was not used. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 13)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper oxide was used instead of copper lactate, 33 parts by mass of ethylene glycol was used instead of pentaerythritol, and 30 parts by mass of toluene was used instead of terpineol. .. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 14)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of copper oxide was used instead of copper lactate, 33 parts by mass of ascorbic acid was used instead of pentaerythritol, and 30 parts by mass of toluene was used instead of terpineol. .. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 15)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of silver acetate was used instead of copper lactate, 33 parts by mass of ethylene glycol was used instead of pentaerythritol, and 30 parts by mass of toluene was used instead of terpineol. .. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

(Comparative Example 16)
A bonding material paste was prepared in the same manner as in Example 1 except that 37 parts by mass of silver acetate was used instead of copper lactate, 33 parts by mass of ascorbic acid was used instead of pentaerythritol, and 30 parts by mass of toluene was used instead of terpineol. .. Further, the copper plate A and the copper plate B were joined in the same manner as in Example 1 except that this bonding material paste was used to prepare a test piece for measuring the bonding strength.

<Measurement of joint strength>
The joint strength of the test pieces for measuring the joint strength obtained in Examples and Comparative Examples was measured using a precision universal testing machine (“Autograph AG-IS” manufactured by Shimadzu Corporation). That is, as shown in FIG. 1, a hole is made in each of the copper plate A and the copper plate B of the test piece for measuring the joint strength, a wire is passed through the hole, a tensile test is performed at a shear rate of 1 mm / min, and the maximum load at break is measured. did. This maximum load was divided by the joint area (length 10 mm × width 10 mm) to determine the joint strength (shear strength). This measurement was performed on three test pieces, and the average value was calculated. The obtained joint strength (average value) was evaluated according to the following criteria. The results are shown in Tables 1 to 5.
A: 4 MPa or more.
B: 1 MPa or more and less than 4 MPa.
C: Less than 1 MPa.

As shown in Tables 1 and 2, it was found that the bonding material of the present invention can bond copper plates to each other at a low temperature of 300 ° C. or lower with high bonding strength. As shown in Table 2, it was found that the bonding strength was particularly high when the firing temperature was 260 to 275 ° C.

Further, as shown in Table 1, when copper lactate or copper glycolate was used as the hydroxycarboxylate (Examples 1 and 2), copper malate or copper tartrate was used (Example 3). It was found that the bonding strength was higher than that in 4). Furthermore, when pentaerythritol, diglycerin or glycerin is used as the alcohol (Examples 5 to 7), the bonding strength may be higher than when xylitol or lactose is used (Examples 8 to 9). all right.

On the other hand, as shown in Tables 3 to 4, when a copper salt of a hydroxycarboxylic acid having 8 carbon atoms (2-hydroxy-n-copper octanate) was used as the hydroxycarboxylic acid copper (Comparative Example 1). When a copper salt of a carboxylic acid having no hydroxy group (copper acetate, copper formate, copper caprylate) is used instead of the hydroxycarboxylic acid copper (Comparative Examples 2 to 4), instead of an alcohol having 3 to 12 hydroxy groups. When an alcohol having 1 to 2 hydroxy groups is used (Comparative Examples 5 to 7), when an acid is used instead of an alcohol having 3 to 12 hydroxy groups (Comparative Examples 8 to 11), an alcohol having 3 to 12 hydroxy groups is used. When not used (Comparative Example 12), it was difficult to join the copper plates to each other at 260 ° C.

Further, when copper oxide or silver acetate is used instead of copper hydroxycarboxylate and ethylene glycol or ascorbic acid is used instead of alcohol having 3 to 12 hydroxy groups (Comparative Examples 13 to 16), the copper plates are 260 to each other. It was difficult to join at ° C.

From the above results, by joining using the joining material of the present invention, it is not necessary to form an oxide layer on the member to be joined, and the joining temperature is lower in the atmosphere (for example, 400 ° C. or lower, preferably 400 ° C. or lower, preferably). It was found that sintering can be performed at 350 ° C. or lower, more preferably 300 ° C. or lower), and a bonding layer having excellent bonding strength can be formed.

As described above, according to the present invention, it is not necessary to form an oxide layer on the member to be joined, and the joining temperature is lower (for example, 400 ° C. or lower, preferably 350 ° C. or lower, more preferably 300 ° C. or lower). However, it is possible to join with high joining strength.

Therefore, the joining material of the present invention is useful as a joining material used for joining a metal member and a member to be joined. In particular, since the bonding material of the present invention can be bonded at a lower bonding temperature (for example, 400 ° C. or lower, preferably 350 ° C. or lower, more preferably 300 ° C. or lower), it is possible to bond electronic components such as semiconductor devices. It is useful as a joining material used when joining a metal member such as a circuit layer such as an electrode or a wiring and a member to be joined of an electronic member such as a semiconductor element.

1: Test piece for measuring joint strength, 11: Copper plate A, 12: Copper plate B, 13: Bonding layer, 2: Wire

Claims (3)

A bonding material comprising a copper salt of a hydroxycarboxylic acid having 1 to 6 carbon atoms and an alcohol having 3 to 12 hydroxy groups. The bonding material according to claim 1, wherein the hydroxycarboxylic acid has 2 to 4 carbon atoms. A step of forming a bonding material layer between a bonded surface of a metal member and a bonded surface of a non-bonded member using the bonding material according to claim 1 or 2.
A step of heating the bonding material layer to sintered the bonding material to form a bonding layer, and bonding the metal member and the non-bonding member via the bonding layer.
A joining method comprising.

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