JP2015010214A - Solder composition and thermosetting resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solder composition that has both sufficient solder meltability and sufficient resin curability.SOLUTION: The solder composition contains not less than 50 mass% to not more than 90 mass% of a lead-free solder power having a melting point of 240°C or lower, not less than 10 mass% to not more than 40 mass% of a thermosetting resin composition containing a thermosetting resin and an aromatic carboxylic acid. The aromatic carboxylic acid is a compound having a benzene ring or a naphthalene ring in which one of hydrogen atoms of the benzene ring or the naphthalene ring is substituted with a carboxylic group and one or two of hydrogen atoms are substituted with at least any one of a hydroxyl group, a methoxy group, an ethoxy group, a protoxy group and an acetoxy group.

Description

  The present invention relates to a solder composition for connecting an electronic component and a wiring board, and a thermosetting resin composition for the solder composition.

  In recent years, electronic devices have been reduced in size and weight, and at the same time, high-density mounting of wiring boards has been advanced. Semiconductor packages have also been downsized, and BGA and LGA, which are grid array type electronic components, have also been downsized into chip size packages (hereinafter also referred to as CSP). As the size of the package is further reduced, the connection terminal pitch is reduced, and a CSP having a pitch of 0.5 mm has become widespread. As a result, since the connection terminal itself needs to be small, the connection strength between the electronic component and the wiring board is weakened. As one of the strengthening measures, a method of putting an underfill agent between an electronic component and a wiring board and curing it has been put into practical use. However, there is a drawback that the mounting process becomes long, or repair is not possible when an electronic component or a bonding failure is found.

  Therefore, it is required to improve the connection strength between the electronic component and the wiring board by using a solder paste. For example, it contains a flux containing a thermosetting resin, an organic acid, a solvent and a curing agent, and a solder powder. A solder paste has been proposed (for example, Patent Document 1).

JP 2001-219294 A

However, the solder paste described in Patent Document 1 has a problem that the resin curability is insufficient, and it is necessary to perform after-cure after reflow as necessary.
On the other hand, in order to improve the resin curability, it may be possible to adjust the amount of the curing component. However, if the resin curability is increased, the solder meltability is lowered. Thus, solder meltability and resin curability are in a trade-off relationship, and it has been difficult to achieve both.

  Then, an object of this invention is to provide the solder composition which has sufficient resin meltability while having sufficient solder meltability, and the thermosetting resin composition for this solder composition.

  The solder composition of the present invention is a lead-free solder powder having a melting point of 240 ° C. or less, 50 mass% to 90 mass%, and a thermosetting resin composition containing 10% by mass of a thermosetting resin and an aromatic carboxylic acid. The aromatic carboxylic acid has a benzene ring or a naphthalene ring, and one of the hydrogen atoms of the benzene ring or the naphthalene ring is substituted with a carboxyl group, and the benzene ring Or one or two hydrogen atoms of the naphthalene ring is a compound substituted with at least one of a hydroxy group, a methoxy group, an ethoxy group, a protoxy group, a butoxy group and an acetoxy group It is.

In the solder composition of the present invention, the aromatic carboxylic acid is preferably 2,4-dihydroxybenzoic acid.
In the solder composition of the present invention, it is preferable that the thermosetting resin composition further contains 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

  The thermosetting resin composition of the present invention contains a thermosetting resin and an aromatic carboxylic acid, and the aromatic carboxylic acid has a benzene ring or a naphthalene ring, and a hydrogen atom of the benzene ring or the naphthalene ring. Is substituted with a carboxyl group, and one or two hydrogen atoms of the benzene ring or the naphthalene ring are at least one of a hydroxy group, a methoxy group, an ethoxy group, a protoxy group, a butoxy group, and an acetoxy group It is characterized by being a compound substituted by.

The reason why the solder composition of the present invention has sufficient solder meltability and sufficient resin curability is not necessarily clear, but the present inventors speculate as follows.
That is, in the solder composition of the present invention, the aromatic carboxylic acid not only acts as a solder activator but also acts as a curing component that cures the thermosetting resin. The aromatic carboxylic acid in the present invention has a carboxyl group and a hydroxy group. In the aromatic carboxylic acid in the present invention, the carboxyl group mainly contributes to the activity of the solder, and the hydroxyl group mainly contributes to the curing of the thermosetting resin such as an epoxy resin. Accordingly, if the number of hydroxy groups in the aromatic carboxylic acid is increased, the polymerization is facilitated and the resin curability can be improved. However, if there are too many hydroxy groups in the aromatic carboxylic acid, the solder meltability will decrease as polymerization proceeds. In the present invention, from the above viewpoint, by adjusting the number of hydroxy groups and carboxyl groups of the aromatic carboxylic acid within a predetermined range, it is possible to achieve both solder meltability and resin curability, which has been difficult in the past. The present inventors speculate that this is possible.

  ADVANTAGE OF THE INVENTION According to this invention, while having sufficient solder meltability, the solder composition which has sufficient resin curability can be provided.

First, the solder composition and thermosetting resin composition of the present invention will be described.
The solder composition of the present invention is a solder composition for connecting an electronic component and a wiring board. And this solder composition contains 50 mass% or more and 90 mass% or less of the lead-free solder powder demonstrated below, and 10 mass% or more and 50 mass% or less of the thermosetting resin composition demonstrated below.
When the content of the lead-free solder powder is less than 50% by mass (when the content of the thermosetting resin composition exceeds 50% by mass), the electronic component is bonded with the obtained solder composition. When sufficient solder joints cannot be formed between the wiring board and the electronic component and the wiring board, the electrical conductivity between the electronic component and the wiring board becomes insufficient. On the other hand, the content of lead-free solder powder exceeds 90% by mass (thermosetting When the content of the resin composition is less than 10% by mass), the bonding strength between the electronic component and the wiring board is insufficient when the resulting solder composition is adhered. Further, in the obtained solder composition, from the viewpoint of achieving a balance between connection strength and conductivity, the content of the lead-free solder powder is preferably 60% by mass or more and 90% by mass or less, and 70% by mass. More preferably, it is 85 mass% or less.

[(A) Lead-free solder powder]
The lead-free solder powder (A) used in the present invention has a melting point of 240 ° C. or lower. When the lead-free solder powder having a melting point exceeding 240 ° C. is used, it is difficult to melt the lead-free solder powder at a normal bonding temperature in the solder composition.
Here, the lead-free solder powder refers to a solder metal or alloy powder to which lead is not added. However, it is allowed that lead is present as an inevitable impurity in the lead-free solder powder, but in this case, the amount of lead is preferably 100 mass ppm or less.

The lead-free solder powder is at least one selected from the group consisting of tin (Sn), copper (Cu), silver (Ag), bismuth (Bi), antimony (Sb), indium (In), and zinc (Zn). It is preferred to include a seed metal.
Moreover, as a specific solder composition (mass ratio) in the said lead-free solder powder, the following can be illustrated.
As binary alloys, for example, Ag-Bi type such as 95.3Ag / 4.7Bi, Ag-Li type such as 66Ag / 34Li, Ag-In type such as 3Ag / 97In, Ag-type such as 67Ag / 33Te, etc. Te, Ag-Tl such as 97.2Ag / 2.8Tl, Ag-Zn such as 45.6Ag / 54.4Zn, Au-Sn such as 80Au / 20Sn, 52.7Bi / 47.3In, etc. Bi-In series, 35In / 65Sn, 51In / 49Sn, In-Sn series such as 52In / 48Sn, Bi-Zn series such as 8.1Bi / 91.9Zn, Sn-Bi series such as 43Sn / 57Bi, 42Sn / 58Bi , 98Sn / 2Ag, 96.5Sn / 3.5Ag, 96Sn / 4Ag, Sn-Ag series such as 95Sn / 5Ag, 91Sn / 9Zn, 30Sn / 7 Sn-Zn-based, such as Zn, Sn-Cu system, such 99.3Sn / 0.7Cu, include Sn-Sb system, such as 95Sn / 5Sb. +
Examples of ternary alloys include Sn—Ag—In such as 95.5Sn / 3.5Ag / 1In, Sn—Zn—In such as 86Sn / 9Zn / 5In, 81Sn / 9Zn / 10In, and 95.5Sn. Sn-Ag-Cu systems such as /0.5Ag/4Cu, 96.5Sn / 3.0Ag / 0.5Cu, 98.3Sn / 1.0Ag / 0.7Cu, 99.0Sn / 0.3Ag / 0.7Cu 90.5Sn / 7.5Bi / 2Ag, Sn-Bi-Ag system such as 41.0Sn / 58Bi / 1,0Ag, and Sn-Zn-Bi system such as 89.0Sn / 8.0Zn / 3.0Bi. It is done.
Examples of other alloys include Sn / Ag / Cu / Bi system.

  The average particle size of the lead-free solder powder is preferably 10 μm or more and 70 μm or less, and more preferably 20 μm or more and 60 μm or less. If the average particle size of the lead-free solder powder is less than the lower limit, the conductivity between the electronic component and the wiring board tends to decrease. On the other hand, if the upper limit is exceeded, the insulation in the solder composition tends to decrease. . The average particle size can be measured with a dynamic light scattering type particle size measuring device.

[(B) Thermosetting resin]
As the thermosetting resin used in the present invention, a known thermosetting resin can be used as appropriate, but it is particularly preferable to use an epoxy resin from the viewpoint of having a flux action.
In the present invention, having a flux action means that the coating film covers the metal surface of the object to be soldered and shields the atmosphere, like metal rosin flux, and the metal surface of the metal surface is oxidized during soldering. The material is reduced, and the coating film is pushed away by the molten solder to allow contact between the molten solder and the metal surface, and the residue has a function of insulating between the circuits.

As such an epoxy resin, a known epoxy resin can be appropriately used. Examples of such epoxy resins include bisphenol A type, bisphenol F type, biphenyl type, naphthalene type, cresol novolac type, phenol novolac type, and dicyclopentadiene type epoxy resins. These epoxy resins may be used individually by 1 type, and may mix and use 2 or more types. Further, these epoxy resins preferably contain a liquid at normal temperature, and when a solid at normal temperature is used, it is preferably used in combination with a liquid at normal temperature. In addition, among these epoxy resin molds, the dispersibility of the metal particles and the paste viscosity can be adjusted, and further, the resistance to the drop impact of the cured product can be improved, and the wettability of the solder can be improved. Liquid bisphenol A type, liquid bisphenol F type, liquid hydrogenated bisphenol A type, naphthalene type, dicyclopentadiene type, and biphenyl type are preferable, and liquid bisphenol A type, liquid bisphenol F type, and biphenyl type are more preferable.
As content of the said epoxy resin, it is preferable that it is 50 to 99 mass% with respect to 100 mass% of thermosetting resin compositions, and it is more preferable that it is 55 to 85 mass%. 60 mass% or more and 71 mass% or less is especially preferable. If the content of the epoxy resin is less than the lower limit, sufficient strength for fixing the electronic component cannot be obtained, and thus the resistance to drop impact tends to decrease. On the other hand, if the content exceeds the upper limit, the thermosetting resin The content of the curing component in the composition is decreased, and the rate at which the epoxy resin is cured tends to be delayed.

[(C) aromatic carboxylic acid]
The aromatic carboxylic acid used in the present invention has a benzene ring or a naphthalene ring, and one of the hydrogen atoms of the benzene ring or the naphthalene ring is substituted with a carboxyl group, and the hydrogen atom of the benzene ring or the naphthalene ring One or two of these are compounds substituted with at least one of a hydroxy group and a methoxy group. When the number substituted with carboxyl groups is 2 or more, the insulation in the solder composition becomes insufficient. Moreover, when the number substituted by the hydroxy group or the methoxy group is 3 or more, the solder meltability in the solder composition becomes insufficient. Furthermore, from the viewpoint of resin curability, the number substituted with a hydroxy group or a methoxy group is more preferably two.
The aromatic carboxylic acid may have any aromatic ring of a benzene ring and a naphthalene ring, but preferably has a benzene ring.
The aromatic carboxylic acid may have any substituent among a hydroxy group, a methoxy group, an ethoxy group, a protoxy group, a butoxy group and an acetoxy group, but preferably has a hydroxy group. In the aromatic carboxylic acid, from the viewpoint of solder meltability and resin curability, the hydroxy group is preferably in the ortho position or meta position of the carboxyl group, and in the ortho position and meta position of the carboxyl group. Is more preferable.
One or two hydrogen atoms of the benzene ring or the naphthalene ring in the aromatic carboxylic acid may be further substituted with at least one of an alkyl group having 1 to 4 carbon atoms and a formyl group.

  Examples of the aromatic carboxylic acid include 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3, 5-dihydroxybenzoic acid, 2-hydroxybenzoic acid, 4-hydroxybenzoic acid, 3,5-dimethoxybenzoic acid, 2-hydroxy-3-naphthoic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid , 5-formylsalicylic acid and the like. Among these, 2,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, and 3,5-dimethoxybenzoic acid are preferable, and 2,4-dihydroxybenzoic acid is particularly preferable. These aromatic carboxylic acids may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The content of the aromatic carboxylic acid is preferably 1% by mass or more and 50% by mass or less, and preferably 2% by mass or more and 35% by mass or less with respect to 100% by mass of the thermosetting resin composition. More preferably, it is 7 mass% or more and 30 mass% or less, and it is still more preferable that it is 12 mass% or more and 20 mass% or less. If the content of the aromatic carboxylic acid is less than the lower limit, the curing rate tends to be delayed due to a delay in the rate of curing the thermosetting resin such as an epoxy resin. On the other hand, if the content exceeds the upper limit, the resulting solder composition There is a tendency that the insulation in the object is lowered.

  In addition to the thermosetting resin and the aromatic carboxylic acid, the thermosetting resin composition used in the present invention includes 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, thixo An agent and a curing agent may be contained.

[(D) HCA]
As (D) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter also referred to as “HCA”) used in the present invention, a commercially available product can be used as appropriate. With this HCA, it is possible to further improve the solder meltability while maintaining the resin curability in the solder composition.
The content of the HCA is preferably 0.5% by mass or more and 15% by mass or less, and more preferably 3% by mass or more and 8% by mass or less with respect to 100% by mass of the thermosetting resin composition. preferable. If the content of HCA is less than the lower limit, the effect of improving the solder melting property tends to be difficult to obtain. On the other hand, if the upper limit is exceeded, the insulating property is lowered and the solder melting property is lowered due to resin curing. is there.

As the thixotropic agent used in the present invention, a known thixotropic agent can be appropriately used. Examples of such thixotropic agents include organic thixotropic agents (fatty acid amide, hydrogenated castor oil, olefinic wax, etc.) and inorganic thixotropic agents (colloidal silica, benton, etc.). These thixotropic agents may be used alone or in combination of two or more. Among these, fatty acid amide, colloidal silica, and benton are preferable. Moreover, it is preferable to use it in combination with an organic thixotropic agent and an inorganic thixotropic agent from a viewpoint of the difficulty of bleeding of the solder composition obtained. Specifically, a combination of fatty acid amide and colloidal silica, and a combination of fatty acid amide and benton are exemplified.
The thixotropic agent content is preferably 0.5% by mass or more and 25% by mass or less, and preferably 1% by mass or more and 20% by mass or less, with respect to 100% by mass of the thermosetting resin composition. More preferably, it is 10 mass% or more and 15 mass% or less. If the content of the thixotropic agent is less than the above lower limit, thixotropy cannot be obtained, the sagging is likely to occur on the electrode of the wiring board, and the adhesion force when electronic components are mounted on the wiring board electrode tends to decrease. On the other hand, if the upper limit is exceeded, the thixotropy is too high and the syringe needles tend to become defective due to clogging.

As the curing agent used in the present invention, a known curing agent can be appropriately used. For example, when an epoxy resin is used as the thermosetting resin, the following can be used. One of these curing agents may be used alone, or two or more thereof may be mixed and used.
Examples of the latent curing agent include NOVACURE HX-3722, HX-3721, HX-3748, HX-3088, HX-3613, HX-392HP, and HX-3941HP (trade name, manufactured by Asahi Kasei Epoxy Co., Ltd.).
Examples of the aliphatic polyamine curing agent include Fujicure FXR-1020, FXR-1030, FXR-1050, FXR-1080 (trade name, manufactured by Fuji Kasei Kogyo Co., Ltd.).
Examples of the epoxy resin amine adduct-based curing agent include Amicure PN-23, PN-F, MY-24, VDH, UDH, PN-31, and PN-40 (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name), EH-3615S. EH-3293S, EH-3366S, EH-3842, EH-3670S, EH-3636AS, EH-4346S, EH-5016S (trade name, manufactured by ADEKA).
Examples of the imidazole curing accelerator include 2P4MHZ, 2MZA, 2PZ, C11Z, C17Z, 2E4MZ, 2P4MZ, C11Z-CNS, and 2PZ-CNZ (and above, trade names).

  As content of the said hardening | curing agent, it is preferable that it is 0.5 mass% or more and 10 mass% or less with respect to 100 mass% of thermosetting resin compositions, and it is 1 mass% or more and 5 mass% or less. More preferred. If the content of the curing agent is less than the lower limit, the rate at which the thermosetting resin is cured tends to be delayed. On the other hand, if the upper limit is exceeded, the reactivity tends to be faster and the paste usage time tends to be shorter. .

  In addition to the epoxy resin, the aromatic carboxylic acid, the HCA, the thixotropic agent, and the curing agent, a thermosetting resin composition used in the present invention is optionally provided with a surfactant, a coupling agent, and an antifoaming agent. It may contain additives such as an agent, a powder surface treatment agent, a reaction inhibitor, and an anti-settling agent. The content of these additives is preferably 0.01% by mass or more and 10% by mass or less, and 0.05% by mass or more and 5% by mass or less with respect to 100% by mass of the thermosetting resin composition. More preferably. If the content of the additive is less than the lower limit, the effect of each additive tends to be difficult to achieve. On the other hand, if the content exceeds the upper limit, the bonding strength due to the thermosetting resin composition tends to decrease.

Next, a method for connecting electrodes such as a wiring board and an electronic component using the solder composition of the present invention will be described. Here, the case where the electrodes of the wiring board and the electronic component are connected will be described as an example.
Thus, as a method of connecting the electrodes of the wiring board and the electronic component, an application step of applying the solder composition on the wiring board, and arranging the electronic component on the solder composition, and using a reflow furnace And a reflow process of heating the electronic component on the wiring board under a predetermined condition.

In the applying step, the solder composition is applied onto the wiring board.
Examples of the coating apparatus used here include a dispenser, a screen printing machine, a jet dispenser, and a metal mask printing machine.
The thickness of the coating film is not particularly limited, but is preferably 50 μm or more and 500 μm or less, and more preferably 100 μm or more and 300 μm or less. If the thickness is less than the lower limit, the adhesive force when electronic components are mounted on the electrodes of the wiring board tends to decrease. On the other hand, if the thickness exceeds the upper limit, the paste tends to protrude beyond the connection portion. .

In the reflow process, the electronic component is placed on the solder composition and heated in a reflow furnace under predetermined conditions. By this reflow process, sufficient soldering can be performed between the electronic component and the wiring board, and the resin can be cured. As a result, the electronic component can be mounted on the wiring board.
What is necessary is just to set reflow conditions suitably according to melting | fusing point of solder. For example, when using a Sn—Ag—Cu-based solder alloy, prebaking may be performed at a temperature of 150 to 180 ° C. for 60 to 120 seconds, and a peak temperature may be set to 230 to 250 ° C.

In addition, in the method of connecting the electrodes of the wiring board and the electronic component in this way, a thermocompression bonding process described below may be provided instead of the reflow process or as a pre-process of the reflow process.
In the thermocompression bonding step, the electronic component is disposed on the solder composition, and the electronic component is thermocompression bonded to the wiring board at a temperature higher by 1 ° C. than the melting point of the solder powder.
If the temperature at the time of thermocompression bonding does not satisfy the condition that the temperature is higher than the melting point of the solder powder by 1 ° C. or more, the solder cannot be sufficiently melted and sufficient solder bonding between the electronic component and the wiring board is possible. Cannot be formed, and the electrical conductivity between the electronic component and the wiring board becomes insufficient.
The temperature during thermocompression bonding is preferably 130 ° C. or higher and 200 ° C. or lower, and more preferably 140 ° C. or higher and 180 ° C. or lower.
Although the pressure at the time of thermocompression bonding is not particularly limited, it is preferably 0.05 MPa or more and 3 MPa or less, and more preferably 0.1 MPa or more and 2 MPa or less. If the pressure is less than the upper limit, sufficient solder joints cannot be formed between the electronic component and the wiring board, and the electrical conductivity between the electronic component and the wiring board tends to decrease. It tends to be stressed and the dead space has to be widened.
In the present invention, as described above, the pressure at the time of thermocompression bonding can be set to a lower pressure range as compared with the case of the conventional method using a conductive filler-based anisotropic conductive material. . Therefore, cost reduction of the apparatus used for a thermocompression bonding process can also be achieved.
The time for thermocompression bonding is not particularly limited, but is usually 1 second to 60 seconds, preferably 2 seconds to 20 seconds, and more preferably 3 seconds to 10 seconds.

In addition, the method for connecting the electrodes of the wiring board and the electronic component as described above may further include a peeling step, a re-coating step, and a re-reflow step described below.
In the peeling step, the electronic component is peeled from the wiring board at a temperature higher by 1 ° C. than the melting point of the solder powder.
Here, the method for peeling the electronic component from the wiring board is not particularly limited. As such a method, for example, a method of peeling the electronic component from the wiring board while heating the connection portion using a soldering iron or the like can be employed. In such a case, a known peeling device used for repair may be used.
Moreover, after peeling an electronic component from a wiring board, you may wash | clean the said wiring board with a solvent etc. as needed.

In the re-application process, the solder composition is applied onto the wiring board after the peeling process. Here, the thickness and thickness of the coating device and the coating film can be the same as those in the coating step and conditions.
In the re-reflow step, the electronic component is placed on the solder composition after the re-application step, and heated under a predetermined condition in a reflow furnace, and the electronic component is mounted on the wiring board. Here, the heating conditions can employ the same conditions as in the reflow process.

  According to the method for connecting electronic components described above, since the electrodes of the electronic component and the wiring board are soldered to each other, the electrodes and conductive fillers are different from the conventional conductive filler-based anisotropic conductive material. Compared with the case where they are connected by contacting each other, extremely high connection reliability can be achieved. In addition, after reflow, if the heat at a temperature equal to or higher than the melting point of the solder powder is applied, the solder can be melted, and the thermosetting resin composition can be softened. Can be peeled off. In the present invention, when a wiring board and an electronic component are connected again using a solder composition after peeling, even if a certain amount of residue (solder, etc.) remains on the electrode, the residue is combined. Soldering can be performed, and conductivity can be ensured. Therefore, the connection method of the electronic component is excellent in repairability as compared with a conventional method using a conductive filler-based anisotropic conductive material.

In addition, the connection method using the solder composition of the present invention is not limited to the connection method described above, and modifications, improvements and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the connection method, the wiring board and the electronic component are bonded by the reflow process, but the present invention is not limited to this. For example, instead of the reflow process, the wiring board and the electronic component may be bonded by a process of heating the solder composition using laser light (laser heating process). In this case, the laser light source is not particularly limited, and can be appropriately selected according to the wavelength matched to the metal absorption band. As the laser light source, for example, a solid laser (ruby, glass, YAG, etc.), semiconductor laser (GaAs, InGaAsP, etc.), (such as a dye) liquid laser, a gas laser (He-Ne, Ar, CO 2, etc. excimer) is Can be mentioned.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples. In addition, the material used in the Example and the comparative example is shown below.
((A) component)
Lead-free solder powder: average particle size is 39 μm, solder melting point is 217-220 ° C., solder composition is 96.5Sn / 3.0Ag / 0.5Cu
((B) component)
Thermosetting resin A: bisphenol A type and bisphenol F type liquid epoxy resin, manufactured by DIC Corporation, trade name “EXA-830LVP”
Thermosetting resin B: biphenyl type epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd., trade name “YX-4000HK”
((C) component)
Aromatic carboxylic acid A: 2,4-dihydroxybenzoic acid aromatic carboxylic acid B: 3,5-dimethoxybenzoic acid aromatic carboxylic acid C: 3,5-dihydroxybenzoic acid aromatic carboxylic acid D: 4-hydroxybenzoic acid Aromatic carboxylic acid E: 2-hydroxy-3-naphthoic acid,
(Other ingredients)
Aromatic carboxylic acid F: gallic acid Aromatic carboxylic acid G: stearyl gallic acid dicarboxylic acid: adipic acid, thixotropic agent manufactured by Kanto Denka Kogyo Co., Ltd., trade name “Sripacs ZHH”
HCA: 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, curing agent manufactured by Sanko Co., Ltd .: modified polyamine, manufactured by ADEKA, trade name “EH-5016S”

[Example 1]
36% by mass of thermosetting resin A, 20% by mass of thermosetting resin B, 14% by mass of thixotropic agent and 30% by mass of aromatic carboxylic acid A are charged in a container, premixed with a stirrer, and then room temperature is set using three rolls. Were mixed and dispersed to obtain a thermosetting resin composition.
Next, 20% by mass of the obtained thermosetting resin composition and 80% by mass of lead-free solder powder (100% by mass in total) were put into a container and mixed in a kneader to prepare a solder composition. .

[Examples 2 to 10]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1.
[Examples 11 to 18]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 2.
[Comparative Examples 1-4]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 3.

<Evaluation of solder composition>
The performance (solder melting, LGA mounting suitability, resin curability, shear strength) of the solder composition was evaluated or measured by the following method. The obtained results are shown in Tables 1 to 3.
(1) Melting of solder The obtained solder composition was applied on a wiring board (on a land) having a plurality of lands having a diameter of 1 mm to 2 mm as a circuit pattern (thickness: 0.2 mm). Then, a chip (electrode: copper electrode with gold plating (Cu / Ni / Au)) was placed on the solder composition after application. Thereafter, reflow was carried out under conditions of pre-baking 150 to 180 ° C. for 90 seconds and a peak temperature of 240 ° C. to prepare a test substrate. About the obtained test substrate, the chip side ball and the solder ball on the land where the chip is not mounted were observed, and the melting of the solder was evaluated according to the following criteria, respectively.
A: There is no solder ball.
○: There are 5 or less solder balls.
Δ: There are 6 or more and 10 or less solder balls.
X: 11 or more solder balls or solder does not melt.
(2) LGA (Land Grid Array) Mounting Suitability A wiring board having a 1.5 mm pitch land (land / space = 750 μm / 750 μm) as a circuit pattern was prepared. The obtained solder composition was applied onto this wiring board (on the land) (thickness: 0.25 mm). And the LGA component which has a 1.5 mm pitch land was arrange | positioned on the solder composition after application | coating. Thereafter, reflow was carried out under conditions of pre-baking 150 to 180 ° C. for 90 seconds and a peak temperature of 240 ° C. to prepare a test substrate. About the obtained test board, the presence or absence of unmelted solder was observed, and LGA mounting suitability was evaluated according to the following criteria.
○: There is no unmelted solder.
X: Solder is not melted.
(3) Resin curability Evaluation is performed using the test substrate prepared in (1). With respect to the obtained test substrate, the resin on the side of the chip and the resin on the land were observed, and the resin curability was evaluated according to the following criteria, respectively.
A: The resin is hard.
○: A mark remains when the resin is pressed strongly.
Δ: A mark remains when the resin is pressed.
X: Resin is soft and has tack.
(4) Shear strength The obtained solder composition was applied on a wiring board (on the land) having a plurality of lands having a diameter of 1 mm to 2 mm as a circuit pattern (thickness: 0.15 mm). A 1608 CR chip (size: 1.6 mm × 0.8 mm) was placed on the solder composition after application. Thereafter, reflow was carried out under conditions of pre-baking 150 to 180 ° C. for 90 seconds and a peak temperature of 240 ° C. to prepare a test substrate. About the obtained test board | substrate, the shear strength (unit: N / mm < ² >) of the chip | tip was measured on conditions of 5 mm / min. In addition, when the shear strength was too low to be measured, it was determined as “not measurable”.

As is apparent from the results shown in Tables 1 to 3, when the wiring board and the electronic component are connected using the solder composition of the present invention (Examples 1 to 18), solder melting, LGA It was confirmed that mounting suitability, resin curability and shear strength were good. Therefore, it was confirmed that the solder composition of the present invention has sufficient solder meltability and sufficient resin curability. For example, from the results of Example 3 and Example 10, it was confirmed that 2,4-dihydroxybenzoic acid is particularly preferable among aromatic carboxylic acids. Furthermore, for example, from the results of Example 3 and Example 7, it was confirmed that the component (D) is preferably further contained.
On the other hand, when a solder composition containing a carboxylic acid other than the component (C) is used instead of the component (C) (Comparative Examples 1 to 4), the solder meltability becomes insufficient, so that the LGA mounting is possible. It turned out to be inappropriate. In particular, it has been found that aliphatic dicarboxylic acids such as adipic acid are insufficient in both solder meltability and resin curability.

  The solder composition of the present invention can be suitably used as a technique for connecting an electronic component and a wiring board.

Claims (4)

Contains 50 mass% or more and 90 mass% or less of lead-free solder powder having a melting point of 240 ° C. or less, and 10 mass% or more and 50 mass% or less of a thermosetting resin composition containing a thermosetting resin and an aromatic carboxylic acid. And
The aromatic carboxylic acid has a benzene ring or a naphthalene ring,
One of the hydrogen atoms of the benzene ring or the naphthalene ring is substituted with a carboxyl group;
One or two hydrogen atoms of the benzene ring or the naphthalene ring are compounds substituted with at least one of a hydroxy group, a methoxy group, an ethoxy group, a protoxy group, a butoxy group, and an acetoxy group. A solder composition. The solder composition according to claim 1,
The said aromatic carboxylic acid is 2, 4- dihydroxy benzoic acid. The solder composition characterized by the above-mentioned. In the solder composition according to claim 1 or 2,
The thermosetting resin composition further contains 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Containing a thermosetting resin and an aromatic carboxylic acid,
The aromatic carboxylic acid has a benzene ring or a naphthalene ring,
One of the hydrogen atoms of the benzene ring or the naphthalene ring is substituted with a carboxyl group;
One or two hydrogen atoms of the benzene ring or the naphthalene ring are compounds substituted with at least one of a hydroxy group, a methoxy group, an ethoxy group, a protoxy group, a butoxy group, and an acetoxy group. A thermosetting resin composition.