JP7011892B2 - Manufacturing method of solder joint material and connection structure - Google Patents

Description

The present invention relates to a solder bonding material containing solder particles in an amount of more than 80% by weight. The present invention also relates to a connection structure using the above solder bonding material and a method for manufacturing the connection structure.

Anisotropic conductive materials including solder are known. The content of the solder particles in the anisotropic conductive material is, for example, 80% by weight or less.

On the other hand, solder bonding materials containing a large amount of solder are known. The solder bonding material is, for example, a solder paste or the like. The content of solder particles in the solder bonding material exceeds, for example, 80% by weight.

In order to obtain various connection structures, the solder bonding material is, for example, a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on)). It is used for (Film))), connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

When electrically connecting the electrodes, the solder bonding material is selectively applied onto the electrodes, which are soldered portions of a circuit board or the like, by, for example, screen printing. Next, semiconductor chips and the like are laminated, the solder is melted, and then solidified. The solidified solder electrically connects the electrodes.

As an example of the anisotropic conductive material, Patent Document 1 below describes an anisotropic conductive material containing conductive particles and a resin component whose curing is not completed at the melting point of the conductive particles. Specific examples of the conductive particles include tin (Sn), indium (In), bismuth (Bi), silver (Ag), copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd). ), Metals such as gallium (Ga) and thallium (Tl), and alloys of these metals are mentioned.

In Patent Document 1, a resin heating step for heating an anisotropic conductive resin to a temperature higher than the melting point of the conductive particles and the curing of the resin component is not completed, and a resin component curing step for curing the resin component. It is described that the electrodes are electrically connected through the above. Further, Patent Document 1 describes that the mounting is performed with the temperature profile shown in FIG. 8 of Patent Document 1. In Patent Document 1, the conductive particles are melted in the resin component whose curing is not completed at the temperature at which the anisotropic conductive resin is heated.

Patent Document 2 below discloses a solder paste containing solder particles and a flux. The flux contains 1.0% by mass or more and less than 2.0% by mass of polyalkyl methacrylate and 5.0% by mass or more and less than 15.0% by mass of stearic acid amide. The viscosity of the solder paste is 50 to 150 Pa · s. It is desirable that the flux is decomposed or evaporated by heating during soldering and does not remain as a residue.

Japanese Unexamined Patent Publication No. 2004-260131 Japanese Unexamined Patent Publication No. 2013-132654

In conventional anisotropic conductive materials and solder bonding materials, conductive particles or solder particles may not be efficiently arranged between the upper and lower electrodes to be connected.

In recent years, the width of electrodes with electrodes or the width between electrodes without electrodes has become narrower with respect to solder bonding materials, and solder paste or the like is selected only on one electrode, which is the soldered portion, by screen printing or the like. It is becoming difficult to apply the soldering material. Therefore, it is assumed that the solder paste is applied so as to straddle a plurality of electrodes adjacent to each other in the lateral direction. However, in this case, a plurality of electrodes adjacent to each other in the lateral direction are electrically connected by solder, and insulation failure is likely to occur.

In particular, in an anisotropic conductive material having a solder particle content of 80% by weight or less, it is difficult for a plurality of electrodes adjacent to each other in the lateral direction to be electrically connected by solder, whereas the solder particle content is high. In a solder paste exceeding 80% by weight, a plurality of electrodes adjacent to each other in the lateral direction are easily electrically connected by the solder. When the solder paste is used, there is a problem that insulation failure is particularly likely to occur when the electrode width or the electrode-to-electrode width is narrow.

An object of the present invention is a solder joint that can efficiently arrange solder between electrodes to be connected even if the electrode width or the width between electrodes is narrow, and can improve conduction reliability and insulation reliability. To provide the material. Another object of the present invention is to provide a connection structure and a method for manufacturing the connection structure using the solder bonding material.

According to a broad aspect of the present invention, a solder containing solder particles, a flux, and a binder, the content of the solder particles exceeds 80% by weight, and the solder particles have an amino group or a thiol group on the outer surface. Solder bonding materials are provided that contain particles or contain a compound having an amino group or a thiol group as at least one of the flux and the binder.

In certain aspects of the solder bonding material according to the present invention, the solder bonding material contains a compound having an amino group or a thiol group as at least one of the flux and the binder.

In certain aspects of the solder bonding material according to the present invention, the compound having an amino group or a thiol group has an amino group or a thiol group at the molecular terminal.

In certain aspects of the solder bonding material according to the present invention, the compound having an amino group or a thiol group is liquid at 25 ° C.

In certain aspects of the solder bonding material according to the present invention, the compound having an amino group or a thiol group has a polyether skeleton.

In a specific aspect of the solder bonding material according to the present invention, at least one of the decomposition temperature and the volatilization temperature of the compound having an amino group or a thiol group is at a melting point of −45 ° C. or higher and 260 ° C. or lower of the solder particles. be.

In a specific aspect of the solder bonding material according to the present invention, at least one of the decomposition temperature and the volatilization temperature of the compound having an amino group or a thiol group is equal to or higher than the melting point of the solder particles and lower than 260 ° C.

In certain aspects of the solder bonding material according to the present invention, the solder bonding material includes a compound having a thiol group as the compound having an amino group or a thiol group.

In certain aspects of the solder bonding material according to the present invention, the solder bonding material includes, as the compound having an amino group or a thiol group, a compound having an amino group and a compound having a thiol group.

In a specific aspect of the solder bonding material according to the present invention, the boiling point of the flux is 180 ° C. or higher and 260 ° C. or lower.

In certain aspects of the solder bonding material according to the present invention, the solder particles have a carboxyl group on the outer surface.

In a particular aspect of the solder bonding material according to the present invention, the solder bonding material is a solder paste, which comprises a first connection target member having a plurality of first electrodes on the surface and a plurality of second electrodes. It is used for electrical connection between the first electrode and the second electrode in the second connection target member having a surface, and is used on the first electrode on the side of the first electrode. It is applied so as to protrude, or is applied on the plurality of the first electrodes so as to straddle the plurality of the first electrodes.

According to a broad aspect of the present invention, a first connection target member having at least one first electrode on the surface, a second connection target member having at least one second electrode on the surface, and the first connection target member. The solder portion for connecting the connection target member and the second connection target member is provided, and the material of the solder portion is the above-mentioned solder joining material, and the first electrode and the second electrode are used. A connection structure is provided in which the solder and the solder are electrically connected to each other by the solder portion.

In a specific aspect of the connection structure according to the present invention, the first connection target member has a plurality of the first electrodes, and the second connection target member has a plurality of the second electrodes. However, the solder portion does not straddle the adjacent first electrodes, and the solder portion does not straddle the adjacent second electrodes.

According to a broad aspect of the present invention, the step of arranging the above-mentioned solder bonding material on the surface of the first connection target member having at least one first electrode on the surface, and the first step of the solder bonding material. A second connection target member having at least one second electrode on the surface is arranged on the surface opposite to the connection target member so that the first electrode and the second electrode face each other. By heating to a temperature equal to or higher than the melting point of the solder particles in the step, a solder portion connecting the first connection target member and the second connection target member is formed by the solder bonding material and Provided is a method for manufacturing a connection structure, comprising a step of electrically connecting the first electrode and the second electrode by the solder portion.

In a specific aspect of the method for manufacturing a connection structure according to the present invention, the solder bonding material is a solder paste, the first connection target member has a plurality of the first electrodes, and the second electrode is present. The member to be connected has a plurality of the second electrodes, and the solder bonding material is arranged on the first electrode so as to protrude laterally from the first electrode. The solder bonding material is arranged on the first electrode of the above so as to straddle the adjacent first electrodes, and the solder portion does not straddle the adjacent first electrodes. , To obtain a connection structure in which the solder portion does not straddle between the adjacent second electrodes.

In certain aspects of the method for producing a connecting structure according to the present invention, the solder bonding material contains a compound having an amino group or a thiol group as at least one of the flux and the binder, and the solder particles. By heating above the melting point of the above, and by heating above at least one of the decomposition temperature and the volatilization temperature of the compound having an amino group or a thiol group, the first connection target member and the first. The solder portion connecting the member to be connected with 2 is formed of the solder bonding material, and the first electrode and the second electrode are electrically connected by the solder portion.

The solder bonding material according to the present invention contains solder particles, a flux, and a binder, and the content of the solder particles exceeds 80% by weight, and the solder particles have an amino group or a thiol group on the outer surface. Since it contains particles or contains a compound having an amino group or a thiol group as at least one of the flux and the binder, the electrodes to be connected even if the electrode width or the solder-to-solder width is narrow. In addition, the solder can be placed efficiently, and the continuity reliability and insulation reliability can be improved.

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained by using the solder bonding material according to the embodiment of the present invention. 2 (a) to 2 (c) are cross-sectional views for explaining each step of an example of a method of manufacturing a connection structure using the solder bonding material according to the embodiment of the present invention. 3 (a) to 3 (c) are cross-sectional views for explaining each step of another example of the method of manufacturing a connection structure using the solder bonding material according to the embodiment of the present invention.

Hereinafter, the details of the present invention will be described.

(Soldering material)
The solder bonding material according to the present invention includes solder particles, a flux, and a binder. In the solder bonding material according to the present invention, the content of the solder particles exceeds 80% by weight. The solder bonding material according to the present invention contains solder particles having an amino group or a thiol group on the outer surface as the solder particles, or an amino group or a thiol group as at least one of the flux and the binder. Contains a compound having. The solder bonding material according to the present invention may contain solder particles having an amino group or a thiol group on the outer surface as the solder particles, and as at least one of the flux and the binder, the amino group or the thiol may be contained. It may contain a compound having a group. The solder bonding material according to the present invention contains solder particles having an amino group or a thiol group on the outer surface as the solder particles, and has an amino group or a thiol group as at least one of the flux and the binder. It may contain a compound having.

In the present invention, since the above configuration is provided, even if the electrode width (line) with the electrodes is narrow or the electrode width (space) without the electrodes is narrow, the solder between the electrodes to be connected is soldered. Can be efficiently arranged, and conduction reliability and insulation reliability can be improved. When the electrode width or the inter-electrode width is narrow, it tends to be difficult to collect the solder on the electrodes, but in the present invention, even if the electrode width or the inter-electrode width is narrow, the solder can be sufficiently collected on the electrodes. can. In the present invention, since the above configuration is provided, when the electrodes are electrically connected, the solder easily collects between the upper and lower facing electrodes, and the solder is efficiently arranged on the electrodes (lines). can do. Further, in the present invention, when the electrode width with the electrode is wide, the solder is arranged more efficiently on the electrode. Further, in the present invention, when the width between the electrodes without electrodes is wide, the insulation reliability between the electrodes adjacent to each other in the lateral direction becomes higher.

Further, in the present invention, it is difficult for a part of the solder to be arranged in the region (space) where the electrode is not formed, and the amount of the solder arranged in the region where the electrode is not formed can be considerably reduced. In the present invention, solder that is not located between the facing electrodes can be efficiently moved between the facing electrodes. Therefore, the continuity reliability between the electrodes can be improved. Moreover, it is possible to prevent electrical connection between electrodes adjacent to each other in the lateral direction that should not be connected, and it is possible to improve insulation reliability.

Further, the solder bonding material according to the present invention may be selectively arranged on one electrode, or may be arranged so as to straddle a plurality of electrodes adjacent to each other in the lateral direction. In recent years, the electrode width or the inter-electrode width has become narrower, and it has become difficult to selectively apply solder paste or the like onto only one electrode, which is a soldered portion, by screen printing or the like. Therefore, it is assumed that the solder paste is applied so as to straddle the plurality of electrodes adjacent in the horizontal direction, and as a result, the plurality of electrodes adjacent in the horizontal direction are easily electrically connected by the solder. There is. In particular, in a solder paste having a solder particle content of more than 80% by weight, there is a problem that a plurality of electrodes adjacent to each other in the lateral direction are easily electrically connected by soldering. In the present invention, it is possible to effectively prevent a plurality of electrodes adjacent to each other in the lateral direction from being electrically connected by soldering. In the present invention, even if a solder bonding material (solder paste, etc.) is applied so as to straddle a plurality of electrodes adjacent to each other in the lateral direction, the solder efficiently moves between the upper and lower electrodes, and as a result, the plurality of electrodes adjacent to each other in the lateral direction are applied. It is possible to effectively prevent the electrodes of the above from being electrically connected by solder.

Further, in the present invention, it is possible to prevent the positional deviation between the electrodes. In the present invention, when the second connection target member is superposed on the first connection target member on which the solder bonding material is arranged on the upper surface, the electrodes of the first connection target member and the electrodes of the second connection target member are used. Even if the first connection target member and the second connection target member are overlapped with each other in a state where the alignment with the first connection target member is deviated, the misalignment is corrected and the electrode of the first connection target member and the second connection are connected. It can be connected to the electrodes of the target member (self-alignment effect).

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the solder bonding material preferably contains a compound having an amino group or a thiol group as at least one of the flux and the binder. The solder bonding material may contain a compound having an amino group or a thiol group as the flux, and may contain a compound having an amino group or a thiol group as the binder. The solder bonding material may contain a compound having an amino group or a thiol group as the flux, and may contain a compound having an amino group or a thiol group as the binder.

The compound having an amino group or a thiol group may not be a thermosetting compound, may not be a photocurable compound, may not be a thermosetting agent, and may not be a photopolymerization initiator.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the compound having an amino group or a thiol group is preferably having an amino group or a thiol group at the molecular terminal. The compound having an amino group or a thiol group preferably has an amino group or a thiol group at the molecular end of the molecular end and the molecular side chain. When an amino group or a thiol group is present at the end of the molecule, the amino group or the thiol group tends to promote the movement of the solder particles between the upper and lower electrodes.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, it is preferable that the compound having an amino group or a thiol group is liquid at 25 ° C.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, it is preferable that the compound having an amino group or a thiol group has a polyether skeleton.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, at least one of the decomposition temperature and the volatilization temperature of the compound having an amino group or a thiol group is the melting point of the solder particles of −50 ° C. or higher and 260 ° C. It is preferably the following, more preferably the melting point of the solder particles is −45 ° C. or higher and 260 ° C. or lower, further preferably the melting point of the solder particles is −38 ° C. or higher and 260 ° C. or lower, and the solder particles. It is even more preferable that the temperature is equal to or higher than the melting point of 260 ° C. or lower. It is particularly preferable that at least one of the decomposition temperature and the volatilization temperature is the melting point of the solder particles + 5 ° C. or higher, and most preferably the melting point of the solder particles + 10 ° C. or higher. The lower of the decomposition temperature and the volatilization temperature is preferably the melting point of the solder particles of −50 ° C. or higher, more preferably the melting point of the solder particles of −45 ° C. or higher, and the solder particles of the solder particles. The melting point is more preferably −38 ° C. or higher, further preferably higher than the melting point of the solder particles, particularly preferably the melting point of the solder particles + 5 ° C. or higher, and the melting point of the solder particles + 10 ° C. or higher. Most preferably. By using such a compound having an amino group or a thiol group, the compound having an amino group or a thiol group can be removed after solder bonding, and the residue of the compound having an amino group or a thiol group can be reduced. It is possible to prevent adverse effects due to a compound having a group or a thiol group.

The compound having an amino group or a thiol group may have an amino group, may have a thiol group, or may have an amino group and a thiol group. From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the solder bonding material may include a compound having an amino group and a compound having a thiol group as the compound having an amino group or a thiol group. preferable.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the total content of the compound having an amino group or a thiol group in 100% by weight of the solder bonding material is preferably 2% by weight or more, more preferably. Is 5% by weight or more, preferably less than 20% by weight, and more preferably 17% by weight or less. From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the total content of the compound having an amino group or a thiol group is preferably 10 in 100% by weight of the components excluding the solder particles in the solder bonding material. By weight% or more, more preferably 25% by weight or more, preferably 90% by weight or less, more preferably 80% by weight or less.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the total content of the compound having an amino group in 100% by weight of the solder bonding material is preferably 1% by weight or more, more preferably 5% by weight. % Or more, preferably less than 20% by weight, more preferably 15% by weight or less. From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the total content of the compound having an amino group is preferably 5% by weight or more in 100% by weight of the components excluding the solder particles in the solder bonding material. , More preferably 25% by weight or more, preferably 90% by weight or less, and more preferably 80% by weight or less.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the total content of the compound having a thiol group in 100% by weight of the solder bonding material is preferably 2% by weight or more, more preferably 3% by weight. % Or more, more preferably 4% by weight or more, particularly preferably 5% by weight or more, preferably 23% by weight or less, more preferably 21% by weight or less, still more preferably 20% by weight or less, still more preferably 18% by weight. % Or less, particularly preferably 17% by weight or less, most preferably 16% by weight or less. From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the total content of the compound having a thiol group is preferably 10% by weight or more in 100% by weight of the components excluding the solder particles in the solder bonding material. , More preferably 15% by weight or more, even more preferably 20 parts by weight or more, still more preferably 25 parts by weight or more, particularly preferably 90% by weight or less, still more preferably 80% by weight or less.

From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the content of the compound having a thiol group is preferably higher than the content of the compound having an amino group in the solder bonding material. From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, in the solder bonding material, the content of the compound having a thiol group and the content of the compound having an amino group in 100% by weight of the solder bonding material are contained. The absolute value of the difference from the amount is preferably 1% by weight or more, more preferably 3% by weight or more. From the viewpoint of efficiently arranging the solder between the upper and lower electrodes, the content of the compound having a thiol group and the amino in the solder bonding material in 100% by weight of the components excluding the solder particles in the solder bonding material. The absolute value of the difference from the content of the compound having a group is preferably 5% by weight or more, more preferably 15% by weight or more.

The solder bonding material can be used as a solder paste, a solder film, or the like. From the viewpoint of more efficiently arranging the solder on the electrodes, the solder bonding material is preferably a solder paste. The solder bonding material is preferably used for electrical connection of electrodes. The solder bonding material is preferably a circuit connection material.

The solder bonding material is the first electrode and the first electrode in a first connection target member having a plurality of first electrodes on the surface and a second connection target member having a plurality of second electrodes on the surface. It is preferably used for electrical connection with the electrode of 2. Since the solder particles can be efficiently moved between the upper and lower electrodes, the solder bonding material may be applied onto the first electrode so as to protrude laterally from the first electrode. Alternatively, it can be applied and used on the plurality of the first electrodes so as to straddle the plurality of the first electrodes. However, the solder bonding material may be applied and used so as not to straddle the plurality of the first electrodes, or may be selectively applied and used on one of the first electrodes. ..

In order to dispose the solder more efficiently on the electrodes, the solder bonding material is preferably liquid at 25 ° C., preferably a solder paste. In order to arrange the solder more efficiently on the electrodes, the viscosity (η25) of the solder bonding material at 25 ° C. is preferably 50 Pa · s or more, more preferably 100 Pa · s or more, still more preferably 150 Pa · s or more. Particularly preferably 200 Pa · s or more, preferably 800 Pa · s or less, more preferably 600 Pa · s or less, still more preferably 500 Pa · s or less, still more preferably 400 Pa · s or less, particularly preferably 300 Pa · s or less. Most preferably, it is 250 Pa · s or less. The viscosity (η25) can be appropriately adjusted depending on the type and amount of the compounding component.

The viscosity (η25) can be measured under the conditions of 25 ° C. and 5 rpm using, for example, an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

Hereinafter, each component contained in the solder bonding material will be described.

(Solder particles)
The solder particles electrically connect between the electrodes of the member to be connected. The solder particles may be solder particles. The solder particles are formed of solder. In the solder particles, both the central portion and the outer surface portion of the conductive portion are formed of solder. The solder particles are particles in which both the central portion of the solder particles and the conductive outer surface are solder. The solder particles do not have base particles as core particles. The solder particles are different from the conductive particles having the base particles and the solder portions arranged on the surface of the base particles. The solder particles contain, for example, solder in an amount of preferably 90% by weight or more, more preferably 95% by weight or more.

From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, the solder particles preferably have a carboxyl group on the outer surface. The outer surface of the solder particles preferably has a carboxyl group or an amino group, preferably a carboxyl group, and preferably an amino group. The solder particles may have a group containing a carboxyl group or an amino group covalently bonded to the outer surface via a Si—O bond, an ether bond, an ester bond or a group represented by the following formula (X). It is more preferable that a group containing a carboxyl group or an amino group is covalently bonded via an ether bond, an ester bond or a group represented by the following formula (X). The group containing a carboxyl group or an amino group may contain both a carboxyl group and an amino group. In the following formula (X), the right end portion and the left end portion represent a binding site.

Hydroxyl groups are present on the surface of the solder. By covalently bonding this hydroxyl group and a group containing a carboxyl group, a stronger bond can be formed than in the case of bonding by another coordination bond (chelate coordination) or the like, so that the connection resistance between the electrodes is lowered. Moreover, solder particles capable of suppressing the generation of voids can be obtained.

In the solder particles, the bonding form between the surface of the solder and the group containing a carboxyl group may not include a coordination bond, or may not include a bond due to a chelate coordination.

From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, the solder particles are compounds having a functional group capable of reacting with a hydroxyl group and a carboxyl group or an amino group (hereinafter referred to as a compound). , Compound X) is preferably used to react the hydroxyl group on the surface of the solder with a functional group capable of reacting with the hydroxyl group. In the above reaction, a covalent bond is formed. By reacting the hydroxyl group on the surface of the solder with the functional group capable of reacting with the hydroxyl group in the compound X, it is possible to easily obtain solder particles in which a group containing a carboxyl group or an amino group is covalently bonded to the surface of the solder. It is also possible to obtain solder particles in which a group containing a carboxyl group or an amino group is covalently bonded to the surface of the solder via an ether bond or an ester bond. By reacting the hydroxyl group on the surface of the solder with a functional group capable of reacting with the hydroxyl group, the compound X can be chemically bonded to the surface of the solder in the form of a covalent bond.

Examples of the functional group capable of reacting with the hydroxyl group include a hydroxyl group, a carboxyl group, an ester group and a carbonyl group. A hydroxyl group or a carboxyl group is preferable. The functional group capable of reacting with the hydroxyl group may be a hydroxyl group or a carboxyl group.

Compounds having a functional group capable of reacting with a hydroxyl group include levulinic acid, glutaric acid, glycolic acid, succinic acid, malic acid, oxalic acid, malonic acid, adipic acid, 5-ketohexanoic acid, 3-hydroxypropionic acid, 4-. Aminobutyric acid, 3-mercaptopropionic acid, 3-mercaptoisobutyl acid, 3-methylthiopropionic acid, 3-phenylpropionic acid, 3-phenylisobutylic acid, 4-phenylbutyric acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentadecanoic acid, Hexadecanoic acid, 9-hexadecenoic acid, heptadecanoic acid, stearic acid, oleic acid, bacsenic acid, linoleic acid, (9,12,15) -linolenic acid, nonadecanoic acid, arachidic acid, decanedic acid, dodecanedic acid and the like. Be done. Glutaric acid or glycolic acid is preferred. As the compound having a functional group capable of reacting with the hydroxyl group, only one kind may be used, or two or more kinds may be used in combination. The compound having a functional group capable of reacting with the hydroxyl group is preferably a compound having at least one carboxyl group.

The compound X preferably has a flux action, and the compound X preferably has a flux action in a state of being bonded to the surface of the solder. The compound having a flux action can remove the oxide film on the surface of the solder and the oxide film on the surface of the electrode. The carboxyl group has a flux action.

Compounds having a flux action include levulinic acid, glutaric acid, glycolic acid, succinic acid, 5-ketohexanoic acid, 3-hydroxypropionic acid, 4-aminobutyric acid, 3-mercaptopropionic acid, 3-mercaptoisobutyl acid, 3- Examples thereof include methylthiopropionic acid, 3-phenylpropionic acid, 3-phenylisobutyl acid and 4-phenylbutyric acid. Glutaric acid or glycolic acid is preferred. Only one kind of the above-mentioned compound having a flux action may be used, or two or more kinds may be used in combination.

From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, the functional group capable of reacting with the hydroxyl group in the compound X is preferably a hydroxyl group or a carboxyl group. The functional group capable of reacting with the hydroxyl group in the compound X may be a hydroxyl group or a carboxyl group. When the functional group capable of reacting with the hydroxyl group is a carboxyl group, the compound X preferably has at least two carboxyl groups. By reacting a partial carboxyl group of a compound having at least two carboxyl groups with a hydroxyl group on the surface of the solder, solder particles in which a group containing the carboxyl group is covalently bonded to the surface of the solder can be obtained.

The method for producing solder particles includes, for example, a step of mixing the solder particles, a compound having a functional group capable of reacting with a hydroxyl group, and a carboxyl group, a catalyst, and a solvent using the solder particles. In the method for producing solder particles, solder particles in which a group containing a carboxyl group is covalently bonded to the surface of the solder can be easily obtained by the mixing step.

Further, in the method for producing solder particles, it is preferable to use the solder particles to mix and heat the solder particles, a compound having a functional group and a carboxyl group capable of reacting with the hydroxyl group, the catalyst and the solvent. .. By the mixing and heating steps, solder particles in which a group containing a carboxyl group is covalently bonded to the surface of the solder can be obtained more easily.

Examples of the solvent include alcohol solvents such as methanol, ethanol, propanol and butanol, acetone, methyl ethyl ketone, ethyl acetate, toluene and xylene. The solvent is preferably an organic solvent, more preferably toluene. As the solvent, only one kind may be used, or two or more kinds may be used in combination.

Examples of the catalyst include p-toluenesulfonic acid, benzenesulfonic acid, 10-camphorsulfonic acid and the like. The catalyst is preferably p-toluenesulfonic acid. Only one type of the catalyst may be used, or two or more types may be used in combination.

It is preferable to heat at the time of the above mixing. The heating temperature is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, preferably 130 ° C. or lower, and more preferably 110 ° C. or lower.

From the viewpoint of effectively reducing the connection resistance in the connection structure and effectively suppressing the generation of voids, the solder particles use an isocyanate compound to react the isocyanate compound with the hydroxyl group on the surface of the solder. It is preferably obtained through a step. In the above reaction, a covalent bond is formed. By reacting the hydroxyl group on the surface of the solder with the isocyanate compound, solder particles in which the nitrogen atom of the group derived from the isocyanate group is covalently bonded to the surface of the solder can be easily obtained. By reacting the isocyanate compound with the hydroxyl group on the surface of the solder, a group derived from the isocyanate group can be chemically bonded to the surface of the solder in the form of a covalent bond.

Further, the silane coupling agent can be easily reacted with the group derived from the isocyanate group. Since the solder particles can be easily obtained, the group containing the carboxyl group is introduced by the reaction using the silane coupling agent having a carboxyl group, or after the reaction using the silane coupling agent. , It is preferable that the silane coupling agent is introduced by reacting a compound having at least one carboxyl group with a group derived from the silane coupling agent. The solder particles are preferably obtained by reacting the hydroxyl group on the surface of the solder with the isocyanate compound using the isocyanate compound, and then reacting the compound having at least one carboxyl group.

From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, it is preferable that the compound having at least one carboxyl group has a plurality of carboxyl groups.

Examples of the isocyanate compound include diphenylmethane-4,4'-diisocyanate (MDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI). Isocyanate compounds other than these may be used. After reacting this compound with the surface of the solder, the residual isocyanate group and the compound having reactivity with the residual isocyanate group and having a carboxyl group are reacted, so that the surface of the solder is represented by the formula (X). A carboxyl group can be introduced through the group to be added.

As the isocyanate compound, a compound having an unsaturated double bond and an isocyanate group may be used. For example, 2-acryloyloxyethyl isocyanate and 2-isocyanatoethyl methacrylate can be mentioned. After reacting the isocyanate group of this compound with the surface of the solder, the compound having a functional group reactive with the remaining unsaturated double bond and having a carboxyl group is reacted to form the solder. A carboxyl group can be introduced on the surface via a group represented by the formula (X).

Examples of the silane coupling agent include 3-isocyanatepropyltriethoxysilane (“KBE-9007” manufactured by Shinetsu Silicone Co., Ltd.) and 3-isocyanatepropyltrimethoxysilane (“Y-5187” manufactured by MOMENTIVE). Only one kind of the silane coupling agent may be used, or two or more kinds thereof may be used in combination.

Examples of the compound having at least one carboxyl group include levulinic acid, glutaric acid, glycolic acid, succinic acid, malic acid, oxalic acid, malonic acid, adipic acid, 5-ketohexanoic acid, 3-hydroxypropionic acid and 4-amino. Buty acid, 3-mercaptopropionic acid, 3-mercaptoisobutyl acid, 3-methylthiopropionic acid, 3-phenylpropionic acid, 3-phenylisobutylic acid, 4-phenylbutyric acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecane Acids, 9-hexadecenoic acid, heptadecanoic acid, stearic acid, oleic acid, baxenoic acid, linoleic acid, (9,12,15) -linolenic acid, nonadecanoic acid, arachidic acid, decanedioic acid, dodecanedic acid and the like. .. Glutaric acid, adipic acid or glycolic acid are preferred. As the compound having at least one carboxyl group, only one kind may be used, or two or more kinds may be used in combination.

Using the isocyanate compound, the hydroxyl group on the surface of the solder is reacted with the hydroxyl group on the surface of the solder, and then the carboxyl group of a part of the compound having a plurality of carboxyl groups is reacted to react with the hydroxyl group on the surface of the solder. Therefore, a group containing a carboxyl group can be retained.

In the method for producing solder particles, the isocyanate compound is reacted with a hydroxyl group on the surface of the solder by using the solder particles and an isocyanate compound, and then the compound having at least one carboxyl group is reacted. , To obtain solder particles to which a group containing a carboxyl group is bonded to the surface of the solder via a group represented by the above formula (X). In the method for producing solder particles, the solder particles in which a group containing a carboxyl group is introduced on the surface of the solder can be easily obtained by the above steps.

Specific examples of the method for manufacturing the solder particles include the following methods. The solder particles are dispersed in an organic solvent, and a silane coupling agent having an isocyanate group is added. Then, a silane coupling agent is covalently bonded to the surface of the solder by using a reaction catalyst of a hydroxyl group and an isocyanate group on the surface of the solder. Next, a hydroxyl group is generated by hydrolyzing the alkoxy group bonded to the silicon atom of the silane coupling agent. The generated hydroxyl group is reacted with the carboxyl group of the compound having at least one carboxyl group.

Moreover, the following method is mentioned as a specific manufacturing method of the said solder particles. Solder particles are dispersed in an organic solvent, and a compound having an isocyanate group and an unsaturated double bond is added. Then, a covalent bond is formed by using a reaction catalyst of a hydroxyl group on the surface of the solder and an isocyanate group. Then, the introduced unsaturated double bond is reacted with the unsaturated double bond and the compound having a carboxyl group.

The reaction catalyst between the hydroxyl group on the surface of the solder and the isocyanate group includes a tin catalyst (dibutyltin dilaurate, etc.), an amine catalyst (triethylenediamine, etc.), a carboxylate catalyst (lead naphthenate, potassium acetate, etc.), and a trialkyl. Examples thereof include a phosphine catalyst (triethylphosphine, etc.).

From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively suppressing the generation of voids, the compound having at least one carboxyl group is a compound represented by the following formula (1). Is preferable. The compound represented by the following formula (1) has a flux action. Further, the compound represented by the following formula (1) has a flux action in a state of being introduced into the surface of the solder.

In the above formula (1), X represents a functional group capable of reacting with a hydroxyl group, and R represents a divalent organic group having 1 to 5 carbon atoms. The organic group may contain a carbon atom, a hydrogen atom and an oxygen atom. The organic group may be a divalent hydrocarbon group having 1 to 5 carbon atoms. The main chain of the organic group is preferably a divalent hydrocarbon group. In the organic group, a carboxyl group or a hydroxyl group may be bonded to a divalent hydrocarbon group. The compound represented by the above formula (1) includes, for example, citric acid.

The compound having at least one carboxyl group is preferably a compound represented by the following formula (1A) or the following formula (1B). The compound having at least one carboxyl group is preferably a compound represented by the following formula (1A), and more preferably a compound represented by the following formula (1B).

In the above formula (1A), R represents a divalent organic group having 1 to 5 carbon atoms. The R in the above formula (1A) is the same as the R in the above formula (1).

In the above formula (1B), R represents a divalent organic group having 1 to 5 carbon atoms. The R in the above formula (1B) is the same as the R in the above formula (1).

It is preferable that a group represented by the following formula (2A) or the following formula (2B) is bonded to the surface of the solder. It is preferable that the group represented by the following formula (2A) is bonded to the surface of the solder, and it is more preferable that the group represented by the following formula (2B) is bonded. In the following formula (2A) and the following formula (2B), the left end portion represents a binding site.

In the above formula (2A), R represents a divalent organic group having 1 to 5 carbon atoms. The R in the above formula (2A) is the same as the R in the above formula (1).

In the above formula (2B), R represents a divalent organic group having 1 to 5 carbon atoms. The R in the above formula (2B) is the same as the R in the above formula (1).

From the viewpoint of enhancing the wettability of the surface of the solder, the molecular weight of the compound having at least one carboxyl group is preferably 10,000 or less, more preferably 1000 or less, still more preferably 500 or less.

The molecular weight means a molecular weight that can be calculated from the structural formula when the compound having at least one carboxyl group is not a polymer and when the structural formula of the compound having at least one carboxyl group can be specified. When the compound having at least one carboxyl group is a polymer, it means the weight average molecular weight.

It is preferable that the solder particles have a solder particle main body and an anionic polymer arranged on the surface of the solder particle main body because the cohesiveness of the solder particles can be effectively enhanced at the time of conductive connection. The solder particles are preferably obtained by surface-treating the main body of the solder particles with an anionic polymer or a compound to be an anionic polymer. The solder particles are preferably a surface-treated product of an anionic polymer or a compound that becomes an anionic polymer. Only one kind of the anion polymer and the compound to be the anion polymer may be used, or two or more kinds may be used in combination. The anionic polymer is a polymer having an acidic group.

As a method of surface-treating the solder particle body with an anionic polymer, for example, as an anionic polymer, a (meth) acrylic polymer copolymerized with (meth) acrylic acid, which is synthesized from a dicarboxylic acid and a diol and has carboxyl groups at both ends. Polyester polymer, polymer obtained by intermolecular dehydration condensation reaction of dicarboxylic acid and having carboxyl groups at both ends, polyester polymer synthesized from dicarboxylic acid and diamine and having carboxyl groups at both ends, and modified poval having carboxyl groups. A method of reacting the carboxyl group of the anionic polymer with the hydroxyl group on the surface of the solder particle body by using (“Gosenex T” manufactured by Nippon Synthetic Chemical Co., Ltd.) can be mentioned.

Examples of the anionic portion of the anionic polymer include the above-mentioned carboxyl group, and other than that, a tosyl group (p-H ₃ CC ₆ H ₄ S (= O) _2- ) and a sulfonic acid ion group (-SO _3-- ⁾ . ), Phosphate ion group (-PO _4- ⁾ and the like.

As another method of surface treatment, a compound having a functional group that reacts with a hydroxyl group on the surface of the solder particle body and further having a functional group that can be polymerized by an addition or condensation reaction is used to solder this compound. Examples thereof include a method of polymerizing on the surface of the particle body. Examples of the functional group that reacts with the hydroxyl group on the surface of the solder particle body include a carboxyl group and an isocyanate group, and examples of the functional group polymerized by the addition and condensation reaction include a hydroxyl group, a carboxyl group, an amino group, and (meth). Acryloyl group is mentioned.

The weight average molecular weight of the anionic polymer is preferably 2000 or more, more preferably 3000 or more, preferably 10,000 or less, and more preferably 8000 or less. When the weight average molecular weight is not less than the above lower limit and not more than the above upper limit, a sufficient amount of charge and flux property can be introduced on the surface of the solder particles. As a result, the cohesiveness of the solder particles can be effectively enhanced at the time of conductive connection, and the oxide film on the surface of the electrode can be effectively removed at the time of connecting the members to be connected.

When the weight average molecular weight is equal to or higher than the lower limit and lower than the upper limit, it is easy to dispose the anionic polymer on the surface of the solder particle body, and the cohesiveness of the solder particles can be effectively enhanced at the time of conductive connection. , The solder can be placed more efficiently on the electrodes.

The weight average molecular weight indicates the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

The weight average molecular weight of the anionic polymer can be determined by dissolving the solder, removing the solder with dilute hydrochloric acid or the like that does not cause decomposition of the anionic polymer, and then measuring the weight average molecular weight of the remaining anionic polymer.

Regarding the amount of the anionic polymer introduced on the surface of the solder particles, the acid value per 1 g of the solder particles is preferably 1 mgKOH or more, more preferably 2 mgKOH or more, preferably 10 mgKOH or less, and more preferably 6 mgKOH or less.

The acid value can be measured as follows. 1 g of solder particles are added to 36 g of acetone and dispersed by ultrasonic waves for 1 minute. Then, phenolphthalein is used as an indicator and titrated with a 0.1 mol / L potassium hydroxide ethanol solution.

The solder is preferably a metal having a melting point of 450 ° C. or lower (low melting point metal). The low melting point metal means a metal having a melting point of 450 ° C. or lower. The melting point of the low melting point metal is preferably 300 ° C. or lower, more preferably 160 ° C. or lower. Further, the solder preferably contains tin. The tin content in 100% by weight of the solder is preferably 30% by weight or more, more preferably 40% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the tin content in the solder is at least the above lower limit, the continuity reliability between the solder and the electrode becomes even higher.

The tin content may be determined using a high frequency inductively coupled plasma emission spectroscopic analyzer (“ICP-AES” manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer (“EDX-800HS” manufactured by Shimadzu Corporation). It is measurable.

By using the solder particles, the solder melts and is bonded to the electrodes, and the solder conducts the electrodes. For example, the solder and the electrode are likely to make surface contact rather than point contact, so that the connection resistance is low. Further, as a result of increasing the bonding strength between the solder and the electrode by using the solder particles, peeling between the solder and the electrode is more difficult to occur, and the conduction reliability is effectively increased.

The low melting point metal is not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. Examples of the alloy include tin-silver alloy, tin-copper alloy, tin-silver-copper alloy, tin-bismuth alloy, tin-zinc alloy, tin-indium alloy and the like. The low melting point metal is preferably tin, tin-silver alloy, tin-silver-copper alloy, tin-bismuth alloy, or tin-indium alloy because of its excellent wettability to the electrode. More preferably, it is a tin-bismuth alloy or a tin-indium alloy.

The solder material is preferably a filler material having a liquidus line of 450 ° C. or lower based on JIS Z3001: welding terminology. Examples of the composition of the solder include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium and the like. A tin-indium system (117 ° C. eutectic) or a tin-bismuth system (139 ° C. eutectic), which has a low melting point and is lead-free, is preferable. That is, the solder preferably does not contain lead, and is preferably a solder containing tin and indium, or a solder containing tin and bismuth.

In order to further increase the bonding strength between the solder and the electrode, the solder is nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, molybdenum. , Palladium and other metals may be contained. Further, from the viewpoint of further increasing the bonding strength between the solder and the electrode, the solder preferably contains nickel, copper, antimony, aluminum or zinc. From the viewpoint of further increasing the bonding strength between the solder and the electrode, the content of these metals for increasing the bonding strength is preferably 0.0001% by weight or more, preferably 0.0001% by weight, based on 100% by weight of the solder. It is less than% by weight.

The average particle size of the solder particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 3 μm or more, preferably 100 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less. When the average particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder can be arranged more efficiently on the electrodes, it is easy to arrange a large amount of solder between the electrodes, and conduction is achieved. The reliability becomes even higher.

The shape of the solder particles is not particularly limited. The shape of the solder particles may be spherical or may be a shape other than a spherical shape such as a flat shape.

The content of the solder particles in 100% by weight of the solder bonding material is more than 80% by weight, preferably 81% by weight or more, more preferably 85% by weight or more, still more preferably 90% by weight or more, and preferably 97. By weight or less, more preferably 95% by weight or less, still more preferably 92% by weight or less. When the content of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder can be arranged more efficiently on the electrodes, it is easy to arrange a large amount of solder between the electrodes, and the conduction reliability is increased. The sex becomes even higher. From the viewpoint of further enhancing the conduction reliability, it is preferable that the content of the solder particles is large.

(binder)
The solder bonding material preferably contains a compound having an amino group or a thiol group as at least one of the flux and the binder. The solder bonding material preferably contains a compound having an amino group or a thiol group as the binder.

Examples of the compound having an amino group or a thiol group that can be used as the binder include a liquid polysulfide polymer, a reaction product of triallyl isocyanurate and dipentaerythritol hexakis (3-mercaptopropionate), and a polyether amine. Can be mentioned.

Examples of the binder other than the compound having an amino group or a thiol group include a polyether polyol and a (meth) acrylic resin.

In 100% by weight of the solder bonding material, the content of the binder is preferably more than 1% by weight, more preferably 5% by weight or more, still more preferably 10% by weight or more, preferably less than 20% by weight, more preferably. Is 17% by weight or less, more preferably 15% by weight or less. When the content of the binder is not less than the above lower limit and not more than the above upper limit, the solder can be arranged more efficiently on the electrodes, it is easy to arrange a large amount of solder between the electrodes, and the conduction reliability. Will be even higher.

(flux)
The solder bonding material preferably contains a compound having an amino group or a thiol group as at least one of the flux and the binder. The solder bonding material preferably contains a compound having an amino group or a thiol group as the flux.

The use of flux allows the solder to be placed more effectively on the electrodes. The flux is not particularly limited. As the flux, a flux generally used for solder bonding or the like can be used.

Examples of the compound having an amino group or a thiol group that can be used as the flux include a reaction product of a carboxylic acid and an amine, a reaction product of a carboxylic acid, aniline and a thiophenol, and the like.

Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an organic acid and pine fat. And so on. Only one kind of the above flux may be used, or two or more kinds may be used in combination.

Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamate and glutaric acid. Examples of the pine fat include activated pine fat and deactivated pine fat. The flux is preferably an organic acid or pine fat having two or more carboxyl groups. The flux may be an organic acid having two or more carboxyl groups, or may be pine fat. The use of organic acids and pine fats having two or more carboxyl groups further enhances the reliability of conduction between the electrodes.

The above-mentioned pine fat is a rosin containing abietic acid as a main component. The flux is preferably rosins, more preferably abietic acid. By using this preferable flux, the conduction reliability between the electrodes is further increased.

The active temperature (melting point) of the flux is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, still more preferably 80 ° C. or higher, preferably 200 ° C. or lower, more preferably 190 ° C. or lower, still more preferably 160 ° C. or higher. ° C. or lower, more preferably 150 ° C. or lower, even more preferably 140 ° C. or lower. When the active temperature of the flux is not less than the above lower limit and not more than the above upper limit, the flux effect is exhibited more effectively and the solder is more efficiently arranged on the electrode. The active temperature (melting point) of the flux is preferably 80 ° C. or higher and 190 ° C. or lower. The active temperature (melting point) of the flux is particularly preferably 80 ° C. or higher and 140 ° C. or lower.

The active temperature (melting point) of the flux is 80 ° C. or higher and 190 ° C. or lower. 104 ° C.), dicarboxylic acids such as suberic acid (melting point 142 ° C.), benzoic acid (melting point 122 ° C.), malic acid (melting point 130 ° C.) and the like.

Further, from the viewpoint of more efficiently arranging the solder on the electrode, the boiling point of the flux is preferably 200 ° C. or lower.

From the viewpoint of more efficiently arranging the solder on the electrodes, the melting point of the flux is preferably higher than the melting point of the solder, more preferably 5 ° C or higher, and further preferably 10 ° C or higher. ..

The flux may be dispersed in the solder bonding material or may be attached to the surface of the solder particles.

Since the melting point of the flux is higher than the melting point of the solder, the solder can be efficiently aggregated on the electrode portion. This is because, when heat is applied at the time of joining, when the electrode formed on the connection target member and the connection target member portion around the electrode are compared, the thermal conductivity of the electrode portion is that of the connection target member portion around the electrode. Because it is higher than the thermal conductivity, the temperature rise of the electrode portion is fast. When the melting point of the solder is exceeded, the inside of the solder melts, but the oxide film formed on the surface does not reach the melting point (active temperature) of the flux and is not removed. In this state, the temperature of the electrode portion reaches the melting point (active temperature) of the flux first, so that the oxide film on the surface of the solder that has come onto the electrode preferentially is removed, and the activated flux causes the solder. By neutralizing the charge on the surface of the solder, the solder can wet and spread on the surface of the electrode. As a result, the solder can be efficiently aggregated on the electrodes.

In 100% by weight of the solder bonding material, the content of the flux is preferably more than 1% by weight, more preferably 2% by weight or more, still more preferably 3% by weight or more, preferably less than 10% by weight, more preferably. Is 8% by weight or less, more preferably 5% by weight or less. When the content of the flux is not less than the above lower limit and not more than the above upper limit, it becomes more difficult to form an oxide film on the surface of the solder and the electrode, and further, the oxide film formed on the surface of the solder and the electrode is more effective. Can be removed.

(Other ingredients)
The solder bonding material may be, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, and the like. It may contain various additives such as lubricants, antistatic agents and flame retardant agents.

(Connection structure and manufacturing method of connection structure)
The connection structure according to the present invention includes a first connection target member having at least one first electrode on the surface, a second connection target member having at least one second electrode on the surface, and the first connection target member. It is provided with a solder portion connecting the connection target member of the above and the second connection target member. In the connection structure according to the present invention, the material of the solder portion is the solder joint material. The solder portion is formed of the solder bonding material. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the solder portion.

In the connection structure according to the present invention, the first connection target member has a plurality of the first electrodes, and the second connection target member has a plurality of the second electrodes and is adjacent to each other. It is preferable that the solder portion does not straddle the first electrodes and that the solder portion does not straddle the adjacent second electrodes.

In the method for manufacturing a connection structure according to the present invention, the step of arranging the above-mentioned solder bonding material on the surface of the first connection target member having at least one first electrode on the surface, and the above-mentioned solder bonding material. A second connection target member having at least one second electrode on the surface on the surface opposite to the first connection target member so that the first electrode and the second electrode face each other. The solder portion connecting the first connection target member and the second connection target member is formed of the solder bonding material by heating the solder particles to the melting point or higher of the solder particles. Moreover, the step of electrically connecting the first electrode and the second electrode by the solder portion is provided.

In the method for manufacturing a connection structure according to the present invention, the solder bonding material may be arranged on the first electrode so as not to protrude laterally from the first electrode.

In the method for manufacturing a connection structure according to the present invention, the solder bonding material is preferably a solder paste. In the method for manufacturing a connection structure according to the present invention, the first connection target member has a plurality of the first electrodes, and the second connection target member has a plurality of the second electrodes. The solder bonding material is placed on the first electrode so as to protrude laterally from the first electrode, or the first electrodes are adjacent to each other on the plurality of the first electrodes. The solder joint material is arranged so as to straddle the space between them, and the solder portion does not straddle between the adjacent first electrodes, and the solder portion straddles between the adjacent second electrodes. It is preferable to obtain a connection structure that is not connected. The solder bonding material may be arranged on the first electrode so as to protrude laterally from the first electrode, or the solder bonding material may be placed so as to straddle between adjacent first electrodes. May be placed.

In the method for producing a connecting structure according to the present invention, the solder bonding material contains a compound having an amino group or a thiol group as at least one of the flux and the binder, and is heated to a temperature equal to or higher than the melting point of the solder particles. By heating the compound to a temperature equal to or higher than at least one of the decomposition temperature and the volatilization temperature of the compound having an amino group or a thiol group, the first connection target member and the second connection target member are used. It is preferable that the solder portion connecting the above is formed of the solder bonding material, and the first electrode and the second electrode are electrically connected by the solder portion.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a connection structure obtained by using the solder bonding material according to the embodiment of the present invention.

The connection structure 1 shown in FIG. 1 is a solder that connects the first connection target member 2, the second connection target member 3, the first connection target member 2, and the second connection target member 3. A unit 4 is provided. The solder portion 4 is formed of the above-mentioned solder bonding material.

The first connection target member 2 has a plurality of first electrodes 2a on the surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by the solder portion 4. The solder portion 4 does not straddle between the adjacent first electrodes 2a and between the adjacent second electrodes 3a.

No solder is present in a region different from the solder portion 4 gathered between the first electrode 2a and the second electrode 3a. In the region different from the solder portion 4, there is no solder separated from the solder portion 4. If the amount is small, the solder may be present in a region different from the solder portion 4 gathered between the first electrode 2a and the second electrode 3a.

An underfill material may be filled in a region where there is no solder portion between the first connection target member and the second connection target member. An underfill material may be filled in a region where there is no solder portion between the first connection target member and the second connection target member, and the connection structure may be used.

From the viewpoint of further enhancing the conduction reliability, when the portion where the first electrode and the second electrode face each other is seen in the stacking direction of the first electrode, the solder portion, and the second electrode, the first It is preferable that the solder portion is arranged in 50% or more (preferably 60% or more, more preferably 70% or more) of the area of 100% of the portions facing each other of the electrode and the second electrode.

Next, an example of a method for manufacturing the connection structure 1 using the solder bonding material according to the embodiment of the present invention will be described.

First, the first connection target member 2 having the first electrode 2a on the surface (upper surface) is prepared. Next, as shown in FIG. 2A, the solder bonding material 11 containing the solder particles 11A is arranged on the surface of the first connection target member 2 (first step). The solder bonding material 11 containing the solder particles 11A is arranged on the first electrode 2a.

The solder bonding material 11 is arranged on the surface of the first connection target member 2 on which the first electrode 2a is provided. In FIG. 2A, the solder bonding material 11 is selectively arranged on each of the first electrodes 2a so as not to straddle the adjacent first electrodes 2a. The solder bonding material 11 is arranged on one first electrode 2a so as to protrude laterally from the first electrode 2a. After the arrangement of the solder bonding material 11, the solder particles 11A are arranged both on the first electrode 2a (line) and on the region (space) where the first electrode 2a is not formed.

The method of arranging the solder bonding material 11 is not particularly limited, and examples thereof include coating with a dispenser, screen printing, and ejection with an inkjet device.

Further, a second connection target member 3 having the second electrode 3a on the surface (lower surface) is prepared. Next, as shown in FIG. 2B, in the solder bonding material 11 on the surface of the first connection target member 2, the surface of the solder bonding material 11 on the surface opposite to the first connection target member 2 side. The second connection target member 3 is arranged in the second step (second step). The second connection target member 3 is arranged on the surface of the solder bonding material 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

Next, the solder bonding material 11 is heated above the melting point of the solder particles 11A (third step). At the time of this heating, the solder particles 11A existing in the region where the electrodes are not formed gather between the first electrode 2a and the second electrode 3a (self-aggregating effect). Further, the solder particles 11A are melted and bonded to each other. Further, it is preferable that the binder is decomposed or volatilized by this heating. Further, it is preferable that the flux is decomposed or volatilized by this heating. As a result, as shown in FIG. 2C, the solder portion 4 connecting the first connection target member 2 and the second connection target member 3 is formed by the solder bonding material 11. The solder portion 4 is formed by joining the plurality of solder particles 11A.

As shown in FIG. 3A, the solder bonding material may be selectively arranged on each of the first electrodes so as to straddle the adjacent first electrodes 2a. In this case, the solder bonding material may be arranged on one first electrode so as to protrude laterally from the first electrode. After that, the connection structure may be obtained through the states shown in FIGS. 3 (b) and 3 (c) corresponding to FIGS. 2 (b) and 2 (c).

The heating temperature in the third step is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, preferably 450 ° C. or lower, more preferably 260 ° C. or lower, still more preferably 250 ° C. or lower, and particularly preferably 200 ° C. or lower. It is below ° C.

After the third step, the first connection target member or the second connection target member can be peeled off from the solder portion for the purpose of correcting the position or remanufacturing. The heating temperature for performing this peeling is preferably the melting point of the solder or higher, more preferably the melting point of the solder (° C.) + 10 ° C. or higher. The heating temperature for performing this peeling may be the melting point (° C.) of the solder + 100 ° C. or lower.

As a heating method in the third step, a method of heating the entire connection structure using a reflow oven or an oven above the melting point of the solder, or a method of locally heating only the solder portion of the connection structure. There is a way to do it.

Examples of the appliance used for the method of locally heating include a hot plate, a heat gun for applying hot air, a soldering iron, an infrared heater, and the like.

When locally heating on a hot plate, use a metal with high thermal conductivity directly under the solder part, and use a material with low thermal conductivity such as fluororesin in other areas where heating is not preferable. , It is preferable to form the upper surface of the hot plate.

The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors and diodes, resin films, printed circuit boards, flexible printed circuit boards, and flexible devices. Examples thereof include electronic components such as flat cables, rigid flexible substrates, glass epoxy substrates, and circuit boards such as glass substrates. The first and second connection target members are preferably electronic components.

Examples of the electrodes provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the connection target member is a flexible printed substrate, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode formed only of aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al and Ga.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

Method for producing binder 1:
Synthesis of compounds with thiol groups:
1 mol of triallyl isocyanurate (TAIC) was added to 3 mol of DPMP-E (dipentaerythritol hexakis (3-mercaptopropionate)) as a radical initiator V-65 (manufactured by Wako Pure Chemical Industries, Ltd., azo-based polymerization started. A compound having a thiol group was synthesized by reacting with the agent) at 60 ° C. for 30 minutes. The boiling point of the obtained compound having a thiol group was 190 ° C.

Method for producing binder 2:
Synthesis of compounds with amino groups:
Reaction of 1 mol of triallyl isocyanurate (TAIC) with 3 mol of bis (hexamethylene) triamine with radical initiator V-65 (azo-based polymerization initiator manufactured by Wako Pure Chemical Industries, Ltd.) at 60 ° C. for 30 minutes. By allowing the compound to be synthesized, a compound having an amino group was synthesized. The boiling point of the obtained compound having an amino group was 180 ° C.

Method for producing binder 3:
Synthesis of compounds with thiol groups:
1 mol of triallyl cyanurate was reacted with 3 mol of TMTP (trimethylolpropane tristhiopropionate) at 60 ° C. for 30 minutes with a radical initiator V-65 (Azo-based polymerization initiator manufactured by Wako Pure Chemical Industries, Ltd.). By allowing the compound to be synthesized, a compound having a thiol group was synthesized. The boiling point of the obtained compound having a thiol group was 170 ° C.

Binder A: Hydrogenated rosin

Method for producing flux 1:
30 parts by weight of tartaric acid and 75 parts by weight of benzylamine were placed in a three-necked flask and dissolved. Then, the flux 1 was obtained by reacting at 150 ° C. under reduced pressure (4 Torr or less) for 2 hours. The boiling point of the obtained flux 1 was 180 ° C.

Flux A: Adipic acid

Method for producing solder particles 1:
Sn-3Ag-0.5Cu solder particles (“ST-5” manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter (median diameter) 5 μm) and citric acid (“citric acid” manufactured by Wako Pure Chemical Industries, Ltd.) are used as a catalyst. By stirring for 8 hours while dehydrating at 90 ° C. in a toluene solvent using a certain p-toluenesulfonic acid, solder particles 1 (CV value 20%) in which a group containing a carboxyl group is covalently bonded to the surface of the solder. Got The melting point of the solder in the solder particles 1 was 218 ° C.

Method for producing solder particles 2:
200 g of Sn-3Ag-0.5Cu solder particles (“ST-5” manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter (median diameter) 5 μm) and a silane coupling agent having an isocyanate group (“KBE-9007” manufactured by Shinetsu Silicone Co., Ltd.” ) 10 g and 70 g of acetone were weighed in a three-necked flask. While stirring at room temperature, 0.25 g of dibutyltin dilaurate, which is a reaction catalyst between the hydroxyl group on the surface of the solder particles and the isocyanate group, was added, and the mixture was heated at 100 ° C. for 2 hours under stirring and a nitrogen atmosphere. Then, 50 g of methanol was added, and the mixture was heated at 60 ° C. for 1 hour under a stirring and nitrogen atmosphere.

Then, the mixture was cooled to room temperature, the solder particles were filtered through a filter paper, and vacuum dried to remove the solvent at room temperature for 1 hour.

The above solder particles are placed in a three-necked flask, 70 g of acetone, 30 g of trimethyl citrate, and 0.5 g of monobutyltin oxide as a transesterification reaction catalyst are added, and the mixture is stirred and at 60 ° C. under a nitrogen atmosphere. Reacted for time.

As a result, the ester group of trimethyl citrate was reacted with the silanol group derived from the silane coupling agent by a transesterification reaction to form a covalent bond.

Then, 10 g of citric acid was added and reacted at 60 ° C. for 1 hour to add citric acid to the residual methyl ester group that had not reacted with the silanol group of trimethyl citrate.

After that, it is cooled to room temperature, the solder particles are filtered with a filter paper, the solder particles are washed with hexane on the filter paper, and the residual trimethyl citrate is unreacted and adheres to the surface of the solder particles by a non-covalent bond. After removing the citric acid, the solvent was removed by vacuum drying at room temperature for 1 hour.

After crushing the obtained solder particles with a ball mill, a sieve was selected so as to have a predetermined CV value.

As a result, solder particles 2 (CV value 20%) were obtained. The melting point of the solder in the solder particles 2 was 218 ° C.

Method for producing solder particles 3:
Fabrication of solder particles with thiol groups on the outer surface:
10 g of a silane coupling agent having a thiol group (“KBM-803” manufactured by Shinetsu Silicone Co., Ltd.), 50 g of acetone, and 20 g of water were weighed in a three-necked flask. The mixture was heated at 60 ° C. for 6 hours under a nitrogen atmosphere while stirring at room temperature.

Then, the mixture was cooled to room temperature, the solder particles were filtered through a filter paper, and vacuum dried to remove the solvent at room temperature for 1 hour. As a result, solder particles 3 (CV value 20%) were obtained. The melting point of the solder in the solder particles 3 was 218 ° C.

Method for producing solder particles 4:
Fabrication of solder particles with amino groups on the outer surface:
10 g of a silane coupling agent having an amino group (“KBM-603” manufactured by Shinetsu Silicone Co., Ltd.), 50 g of acetone, and 20 g of water were weighed in a three-necked flask. The mixture was heated at 60 ° C. for 6 hours under a nitrogen atmosphere while stirring at room temperature.

Then, the mixture was cooled to room temperature, the solder particles were filtered through a filter paper, and vacuum dried to remove the solvent at room temperature for 1 hour. As a result, solder particles 4 (CV value 20%) were obtained. The melting point of the solder in the solder particles 4 was 218 ° C.

Method for producing solder particles 5:
Sn-3Ag-0.5Cu solder particles (“ST-5” manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter (median diameter) 5 μm), SnBi solder particles, “ST-5” manufactured by Mitsui Kinzoku Co., Ltd., average particle diameter (median) Solder particles 5 (CV value 20%) were obtained in the same manner as the solder particles 1 except that the diameter was changed to 5 μm). The melting point of the solder in the solder particles 5 was 139 ° C.

(CV value of solder particles)
The CV value was measured with a laser diffraction type particle size distribution measuring device (“LA-920” manufactured by HORIBA, Ltd.).

Solder particles A: SnBi solder particles, melting point 139 ° C, "ST-5" manufactured by Mitsui Mining & Smelting Co., Ltd., average particle diameter (median diameter) 5 μm

Diethylene glycol monohexyl ether

(Examples 1 to 7 and Comparative Examples 1 and 2)
(1) Preparation of Solder Paste A solder paste was obtained by blending the components shown in Table 1 below in the blending amounts shown in Table 1 below.

(2) Fabrication of connection structure After printing solder paste with a metal mask on an FR-4 substrate on which multiple copper foil lands are formed so as to straddle multiple copper foil lands, 1005 size laminated ceramic capacitor parts. Was mounted on the printed film of the copper foil land with a mounter. Then, under the conditions of a maximum temperature of 260 ° C. and a holding time of 40 seconds, reflow soldering was performed to prepare a connection structure as a test substrate.

(evaluation)
(1) Viscosity The viscosity (η25) of the solder paste at 25 ° C. was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25 ° C. and 5 rpm.

(2) Solder placement accuracy on electrodes 1
In the obtained connection structure, when the portions facing each other of the first electrode and the second electrode are seen in the stacking direction of the first electrode, the solder portion, and the second electrode, the first electrode and the second electrode are used. The ratio X of the area where the solder portion is arranged in the area of 100% of the portions facing each other with the second electrode was evaluated. The solder placement accuracy 1 on the electrode was determined according to the following criteria.

[Criteria for determining solder placement accuracy 1 on electrodes]
○ ○: Ratio X is 70% or more ○ 1: Ratio X is 65% or more and less than 70% ○ 2: Ratio X is 60% or more and less than 65% △ 1: Ratio X is 55% or more and less than 60% △ 2 : Ratio X is 50% or more and less than 55% ×: Ratio X is less than 50%

(3) Confirmation of component mountability It was confirmed whether or not 500 multilayer ceramic capacitors were short-circuited in the obtained connection structure.

The results are shown in Table 1 below.

1 ... Connection structure 2 ... First connection target member 2a ... First electrode 3 ... Second connection target member 3a ... Second electrode 4 ... Solder part 11 ... Solder bonding material 11A ... Solder particles

Claims (15)

Contains solder particles, flux, and binder,
The content of the solder particles exceeds 80% by weight,
The solder particles contain solder particles having an amino group or a thiol group on the outer surface, or contain a compound having an amino group or a thiol group as at least one of the flux and the binder.
The compound having an amino group or a thiol group when contained as a flux is a compound having an amino group, and the compound having the amino group is a reaction product of a carboxylic acid and an amine.
Electricity between the first electrode and the second electrode in a first connection target member having a plurality of first electrodes on the surface and a second connection target member having a plurality of second electrodes on the surface. Solder bonding material used for general connection. The solder bonding material according to claim 1, which contains a compound having an amino group or a thiol group as at least one of the flux and the binder. The solder bonding material according to claim 1 or 2, wherein the compound having an amino group or a thiol group has an amino group or a thiol group at the molecular terminal. The solder bonding material according to any one of claims 1 to 3, wherein the compound having an amino group or a thiol group is liquid at 25 ° C. The solder bonding material according to any one of claims 1 to 4, wherein the compound having an amino group or a thiol group has a polyether skeleton. The invention according to any one of claims 1 to 5, wherein at least one of the decomposition temperature and the volatile temperature of the compound having an amino group or a thiol group is the melting point of the solder particles of −45 ° C. or higher and 260 ° C. or lower. Solder bonding material. The solder bonding material according to claim 6, wherein at least one of the decomposition temperature and the volatile temperature of the compound having an amino group or a thiol group is equal to or higher than the melting point of the solder particles and lower than 260 ° C. The solder bonding material according to any one of claims 1 to 7, which comprises the compound having a thiol group as the compound having an amino group or a thiol group. The solder bonding material according to claim 8, wherein the compound having an amino group or a thiol group includes a compound having an amino group and a compound having a thiol group. The solder bonding material according to any one of claims 1 to 9, wherein the flux has a boiling point of 180 ° C. or higher and 260 ° C. or lower. The solder bonding material according to any one of claims 1 to 10, wherein the solder particles have a carboxyl group on the outer surface. It is a solder paste,
The first electrode is coated so as to protrude laterally from the first electrode, or the plurality of first electrodes are coated so as to straddle the plurality of the first electrodes. The solder bonding material according to any one of claims 1 to 11, which is used thereafter. The step of arranging the solder bonding material according to any one of claims 1 to 12 on the surface of the first connection target member having a plurality of first electrodes on the surface.
A second connection target member having a plurality of second electrodes on the surface opposite to the first connection target member of the solder bonding material is provided with the first electrode and the second electrode. And the process of arranging them so that they face each other
By heating to a temperature equal to or higher than the melting point of the solder particles, a solder portion connecting the first connection target member and the second connection target member is formed by the solder bonding material, and the first connection target member is formed. A method for manufacturing a connection structure, comprising a step of electrically connecting the electrode of the above and the second electrode by the solder portion. The solder bonding material is a solder paste.
The solder bonding material is placed on the first electrode so as to protrude laterally from the first electrode, or the first electrodes are adjacent to each other on the plurality of the first electrodes. The solder bonding material is arranged so as to straddle the space.
13. The thirteenth aspect of the present invention, wherein the solder portion does not straddle between the adjacent first electrodes, and the solder portion does not straddle between the adjacent second electrodes. A method for manufacturing a connection structure. The solder bonding material contains a compound having an amino group or a thiol group as at least one of the flux and the binder.
By heating above the melting point of the solder particles and by heating above at least one of the decomposition temperature and the volatilization temperature of the compound having an amino group or a thiol group, the first connection target member. The solder portion connecting the second electrode and the second connection target member is formed of the solder bonding material, and the first electrode and the second electrode are electrically connected by the solder portion. The method for manufacturing a connection structure according to claim 13 or 14 .

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