JP6585572B2 - Flux composition and solder paste - Google Patents

Description

  The present invention relates to a flux composition and a solder paste.

Conventionally, when an electronic component is bonded to an electronic circuit formed on a substrate (such as a printed wiring board or a silicon wafer), a solder bonding method using a solder paste has been employed. As one of the solder joining methods, there is a printing method in which a solder paste is printed on a substrate.
In this printing method, a metal mask is generally used, and the solder paste is transferred to the substrate side by filling the metal mask opening with a solder paste using a squeegee and separating the substrate from the metal mask. At this time, a phenomenon occurs in which the solder paste adheres to the wall surface of the opening of the squeegee or the metal mask, and the volume and shape transferred to the substrate side are not performed according to the design of the metal mask.
In order to prevent this, the solder paste is required to have so-called printability that can be printed according to the design of the metal mask. In particular, with the finer pitch of electronic component terminals in recent years, metal mask openings have been further miniaturized, so the importance of printability that can be applied to metal masks having such fine openings is important. It is growing.

  As a method for realizing printability that can be applied to a metal mask having such fine openings, a solder paste composition to which paraffin is added has been proposed (Patent Documents 1 to 3).

However, a fine pitch electronic component and a conventional large component may be mixed and mounted on the substrate. Moreover, in order to ensure solder joint reliability, in-vehicle substrates often use a metal mask that is not thin even if the pattern is fine. In these cases, the metal mask is often set to a certain thickness (for example, 150 μm to 160 μm).
As described above, when the opening is fine and the metal mask becomes thick, the aspect ratio of the opening of the metal mask increases, and the solder paste easily adheres to the wall surface of the metal mask opening. For example, when screen printing is performed with a metal mask having a pattern corresponding to a 0.5 mm pitch Quad Flat Package (QFP) and a thickness of 150 μm, the transfer shape of the solder paste is abnormal, and the transfer rate tends to be unstable. In Patent Documents 1 to 3 mentioned above, there is no mention of problems and the like in the case where the opening of the metal mask has a high aspect ratio and the printability to overcome it.

JP 7-132395 A Japanese Patent No. 4396162 JP 2013-71152 A

  This invention solves the said subject, and it aims at providing the flux composition and solder paste which can ensure favorable plate release property and printability irrespective of the thickness and opening diameter of a metal mask.

(1) The flux composition according to the present invention comprises (A) a base resin, (B) a solvent, (C) an activator, and (D) a thixotropic agent, and (B- 1) It contains an ester solvent having no hydroxyl group at the terminal.

(2) In the configuration described in (1) above, the ester solvent (B-1) has two ester bonds.

(3) In the constitution described in (1) or (2) above, the thixotropic agent (D) has (D-1) a fatty acid polyamide structure, and the fatty acid is a long-chain alkyl having 12 to 22 carbon atoms. It includes a thixotropic agent having a group.

(4) In the configuration described in any one of (1) to (3) above, the thixotropic agent (D-1) is pyrolysis gas chromatograph mass spectrometry (temperature rising rate: 20 ° C./min). The characteristic feature is that the detection temperature of the volatilization peak value is from 450 ° C. to 480 ° C.

(5) In the constitution described in any one of (1) to (4) above, the thixotropic agent (D-1) is characterized by showing a chromatogram shown in FIG.

(6) The solder paste according to the present invention includes the flux composition according to any one of (1) to (5) above and a solder alloy powder.

  ADVANTAGE OF THE INVENTION According to this invention, the flux composition and solder paste which can ensure favorable plate release property and printability irrespective of the thickness and opening diameter of a metal mask can be provided.

It is a thixotropic agent (D-1) according to the present embodiment and has a detection temperature of a volatile peak value by 450 ° C. to 480 ° C. by pyrolysis gas chromatography mass spectrometry (temperature increase rate: 20 ° C./min). It is a chromatogram. It is the chromatogram which measured the thixotropic agent used for the Example and comparative example which concern on this invention using the pyrolysis gas chromatograph mass spectrometry (temperature rising rate: 20 degree-C / min).

  One embodiment of the flux composition and solder paste of the present invention is described in detail below. Of course, the present invention is not limited to these embodiments.

(1) Flux composition The flux composition of this embodiment contains (A) base resin, (B) solvent, (C) activator, and (D) thixotropic agent.

(A) Base resin Examples of the base resin (A) include rosin resins, acrylic resins, styrene-maleic acid resins, epoxy resins, urethane resins, polyester resins, phenoxy resins, terpene resins, and polyalkylene carbonates. . Among these, rosin resins and acrylic resins are particularly preferably used. In addition, you may use these individually by 1 type or in mixture of multiple types.

  Examples of the rosin resin include rosin such as tall oil rosin, gum rosin, and wood rosin; rosin derivatives obtained by polymerizing, hydrogenating, heterogenizing, acrylated, maleating, esterifying, or adding phenol to rosin A modified rosin resin obtained by subjecting these rosin or rosin derivative and unsaturated carboxylic acid (acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc.) to a Diels-Alder reaction; Among these, hydrogenated rosin is preferably used from the viewpoint of improving the activation of the flux composition. In addition, you may use these individually by 1 type or in mixture of multiple types.

  The acid value of the rosin resin is preferably 80 mgKOH / g to 350 mgKOH / g, and its weight average molecular weight is preferably 250 Mw to 1,100 Mw.

  Any acrylic resin can be used as long as it is produced by polymerizing a monomer containing (meth) acrylic acid, for example. Moreover, the acrylic resin may be used alone or in combination of two or more.

  The acid value of the acrylic resin is preferably 30 mgKOH / g to 100 mgKOH / g, and the weight average molecular weight is preferably 3,000 Mw to 30,000 Mw.

  The blending amount of the base resin is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less with respect to the total amount of the flux composition.

  The acid value of the base resin is preferably 30 mgKOH / g to 350 mgKOH / g.

  When a rosin resin is used as the base resin, the blending amount is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less, based on the total amount of the flux composition. .

  When an acrylic resin is used as the base resin, the blending amount is preferably 10% by mass or more and 60% by mass or less, and more preferably 15% by mass or more and 50% by mass or less with respect to the total amount of the flux composition.

  Moreover, when using together the said acrylic resin and the said rosin-type resin, it is preferable that the mixture ratio is 10:90 to 50:50 in the ratio of a rosin-type resin: acrylic resin, and is 15:85 to 40:60. It is more preferable.

(B) Solvent Examples of the solvent (B) include isopropyl alcohol, ethanol, acetone, toluene, xylene, ethyl acetate, ethyl cellosolve, butyl cellosolve, hexyl diglycol, (2-ethylhexyl) diglycol, phenyl glycol, and butyl carbitol. , Octanediol, α-terpineol, β-terpineol, tetraethylene glycol dimethyl ether, trimellitic acid tris (2-ethylhexyl), bisisopropyl sebacate and the like can be used. You may use these individually by 1 type or in mixture of multiple types.

In the flux composition of this embodiment, it is preferable that the said solvent (B) contains the ester solvent which does not have a hydroxyl group at the (B-1) terminal.
As the solvent used in the flux composition, a so-called glycol solvent is generally used. However, the flux composition of this embodiment includes an ester solvent (B-1) having no hydroxyl group at the terminal as the solvent (B), so that the opening of the metal mask has a high aspect ratio. Even in this case, it is possible to ensure stable release performance and printability.

Examples of the ester solvent (B-1) include diisobutyl succinate, dibutyl succinate, diisobutyl adipate, diisodecyl adipate, diisopropyl decandioate, and amyl n-octanoate.
Among these, when an ester solvent having two ester bonds is used, the printability of the flux composition and the solder paste can be further improved. Of these, fatty acid dicarboxylic acid diesters are preferred, and diisopropyl decanedioate is particularly preferred. In addition, you may use these individually by 1 type or in mixture of multiple types.

The blending amount of the solvent (B) is preferably 10% by mass or more and 65% by mass or less with respect to the total amount of the flux composition. The blending amount is more preferably 20% by mass or more and 50% by mass or less, and the particularly preferable blending amount is 25% by mass or more and 45% by mass or less.
Moreover, it is preferable that the compounding quantity of the said ester solvent (B-1) is 20 mass% to 100 mass% with respect to the said solvent (B) whole quantity.

(C) Activator Examples of the activator (C) include organic acids, organic halogen compounds, organic acid salts, and organic amine salts. You may use these individually by 1 type or in mixture of multiple types. As the activator (C), bromine and chlorine having 900 ppm or less are preferably used.

Examples of the organic acid include monocarboxylic acid, dicarboxylic acid, and other organic acids.
Examples of the monocarboxylic acid include formic acid, acetic acid, propionic acid, petric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tuberculostearin. Acid, arachidic acid, behenic acid, lignoceric acid, glycolic acid and the like can be mentioned.
Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, and diglycolic acid.
Still other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, picolinic acid and the like.
Among these, picolinic acid is preferably used for the purpose of obtaining good wettability and heat sagging property of the solder paste.
In addition, you may use these individually by 1 type or in mixture of multiple types.

  Examples of the organic halogen compound include dibromobutenediol, dibromosuccinic acid, 5-bromobenzoic acid, 5-bromonicotinic acid, and 5-bromophthalic acid. You may use these individually by 1 type or in mixture of multiple types.

  The compounding amount of the activator (C) is preferably 1% by mass to 20% by mass with respect to the total amount of the flux composition. The more preferable blending amount is 1% by mass to 15% by mass, and the particularly preferable blending amount is 1% by mass to 10% by mass.

(D) Thixotropic agent Examples of the thixotropic agent (D) include hydrogenated castor oil, saturated fatty acid amides, saturated fatty acid bisamides, oxy fatty acids, dibenzylidene sorbitols, and the like. You may use these individually by 1 type or in mixture of multiple types.

  The flux composition of the present embodiment preferably includes a thixotropic agent (D-1) having a fatty acid polyamide structure as the thixotropic agent (D), and the fatty acid having a long-chain alkyl group having 12 to 22 carbon atoms. Note that the long-chain alkyl group may be either a straight-chain or branched-chain group. The long-chain alkyl group may be one that is connected to the long chain by a carbon-carbon bond by repetition.

  The long-chain alkyl group having 12 to 22 carbon atoms constituting the fatty acid has high hydrophobicity, and since the fatty acid is highly polymerized by an amide bond to form a fatty acid polyamide structure, it has higher hydrophobicity. And since the said ester solvent (B-1) does not have a hydroxyl group, ie, has a hydrophobic property, since both have affinity, it is thought that it is easy to carry out a hydrophobic bond. Therefore, by using these together, the release property from the opening of the metal mask is improved, so that stable printability and transfer rate can be ensured even when the opening has a high aspect ratio. it is conceivable that.

  In addition, by using the ester solvent (B-1) and the thixotropic agent (D-1) in combination with the flux composition, a hydrophobic film is formed at the interface between the flux residue formed using this and the air. It is possible to suppress moisture absorption of the flux residue in the air and to suppress the occurrence of migration.

  In addition, it is preferable that the thixotropic agent (D-1) has a detection temperature of the volatilization peak value by gas chromatography mass spectrometry (temperature rising rate: 20 ° C./min) of 450 ° C. to 480 ° C.

In the present embodiment, the volatilization peak value of the thixotropic agent (D-1) is measured using pyrolysis gas chromatography mass spectrometry under the following measurement conditions.
(sample)
The thixotropic agent (D-1) 0.3 mg
(Thermal decomposition)
Pyrolysis device: Multi-shot pyrolyzer EGA / PY-3030D (manufactured by Frontier Laboratories)
Thermal analysis conditions: (evolved gas analysis)
Thermal decomposition conditions: furnace temperature 40-700 ° C (held for 1 minute), interface temperature 320 ° C
(Gas chromatograph mass spectrometry)
Gas chromatograph mass spectrometer: JMS-Q1050GC (manufactured by JEOL Ltd.)
Gas Chromatograph Conditions Capillary Tube: Ultra ALLOY Deactivated Metal Capillary Tube Model No. UADTM-2.5N (manufactured by Frontier Laboratories)
Carrier gas: Helium Inlet temperature: 320 ° C
Column temperature: 350 ° C (hold for 34 minutes)
Split ratio: 1/50
Mass spectrometry conditions Ion source temperature 300 ° C
GC interface temperature 320 ° C
Detector voltage -1000 volt
Ionization current 50μA
Ionization energy 70eV
Cycle time 300msec
Mass range m / z 10-500

As the thixotropic agent (D-1), for example, the Talen VA series (manufactured by Kyoeisha Chemical Co., Ltd.) is preferably used.
In addition, the gas chromatograph when measured under the above measurement conditions shown in FIG. 1 is particularly preferably used as the thixotropic agent (D-1). In addition, these can be used individually by 1 type or in combination of multiple.

The amount of the thixotropic agent (D) is preferably 1% by mass to 10% by mass with respect to the total amount of the flux composition. The blending amount is more preferably 2% by mass to 9% by mass with respect to the total amount of the flux composition.
The amount of the thixotropic agent (D-1) is preferably 1% by mass to 12% by mass with respect to the total amount of the flux composition. The blending amount is more preferably 2% by mass to 9% by mass with respect to the total amount of the flux composition.

Antioxidant Antioxidant can be mix | blended with the flux composition of this embodiment in order to suppress the oxidation of solder alloy powder. Examples of such antioxidants include, but are not limited to, hindered phenolic antioxidants, phenolic antioxidants, bisphenolic antioxidants, polymer-type antioxidants, and the like. Among these, a hindered phenol antioxidant is particularly preferably used. Examples of the hindered phenol-based antioxidant include Irganox 245 (manufactured by BASF Japan Ltd.). These can be used alone or in combination.

  The blending amount of the antioxidant is not particularly limited, but generally it is preferably about 0.5% by mass to 10% by mass with respect to the total amount of the flux composition.

  Moreover, additives, such as an antifoamer, a rust preventive agent, surfactant, a thermosetting agent, and a delustering agent, can be mix | blended with the flux composition of this embodiment. The blending amount of the additive is preferably 10% by mass or less, particularly preferably 5% by mass or less, based on the total amount of the flux composition.

(2) Solder paste The solder paste of this embodiment is obtained by mixing the flux composition and the solder alloy powder.
Examples of the solder alloy powder include an alloy containing tin and lead, an alloy containing tin and lead and at least one of silver, bismuth and indium, an alloy containing tin and silver, an alloy containing tin and copper, tin, silver and An alloy containing copper, an alloy containing tin and bismuth, or the like can be used. Besides these, for example, use a solder alloy powder in which tin, lead, silver, bismuth, indium, copper, zinc, gallium, antimony, gold, palladium, germanium, nickel, chromium, aluminum, phosphorus, etc. are appropriately combined. Can do. Note that elements other than those listed above can be used in combination.

The amount of the solder alloy powder is preferably 65% by mass to 95% by mass with respect to the total amount of the solder paste. A more preferred blending amount is from 85% by weight to 93% by weight, and a particularly preferred blending amount is from 88% by weight to 91% by weight.
When the blending amount of the solder alloy powder is less than 65% by mass, there is a tendency that sufficient solder joints are hardly formed when the obtained solder paste is used. On the other hand, when the content of the solder alloy powder exceeds 95% by mass, the flux composition as the binder is insufficient, and thus the flux composition and the solder alloy powder tend to be difficult to mix.

  Further, the average particle diameter of the solder alloy powder is preferably 20 μm to 38 μm. The average particle size can be measured by a dynamic light scattering type particle size measuring device.

  The solder paste of this embodiment can ensure stable plate release and printability even when the opening portion of the metal mask has a high aspect ratio by using the flux composition.

  In addition, in the above, although embodiment which uses a flux composition for solder paste was described, the use of the flux composition in this embodiment is not limited to this, For example, for other flux uses, such as a bond flux for solder balls Various applications are also possible.

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

Each component described in Table 1 was kneaded to obtain each flux composition. Then, 11% by mass of each of these flux compositions and 89% by mass of Sn-3Ag-0.5Cu solder alloy powder (average particle size 28 μm) were mixed, and Examples 1 to 7, Reference Examples 8, 9 and Comparative Example 1 were mixed. To 4 were prepared.
Unless otherwise specified, the numerical values shown in Table 1 mean mass%.

Moreover, the thixotropic agents used in Examples 1 to 7, Reference Examples 8 and 9 and Comparative Examples 1 to 4 were measured using pyrolysis gas chromatograph mass spectrometry under the following measurement conditions. The gas chromatograph is shown in FIG.
(sample)
0.3mg
(Thermal decomposition)
Pyrolysis device: Multi-shot pyrolyzer EGA / PY-3030D (manufactured by Frontier Laboratories)
Thermal analysis conditions: (evolved gas analysis)
Thermal decomposition conditions: furnace temperature 40-700 ° C (held for 1 minute), interface temperature 320 ° C
(Gas chromatograph mass spectrometry)
Gas chromatograph mass spectrometer: JMS-Q1050GC (manufactured by JEOL Ltd.)
Gas Chromatograph Conditions Capillary Tube: Ultra ALLOY Deactivated Metal Capillary Tube Model No. UADTM-2.5N (manufactured by Frontier Laboratories)
Carrier gas: Helium Inlet temperature: 320 ° C
Column temperature: 350 ° C (hold for 34 minutes)
Split ratio: 1/50
Mass spectrometry conditions Ion source temperature 300 ° C
GC interface temperature 320 ° C
Detector voltage -1000 volt
Ionization current 50μA
Ionization energy 70eV
Cycle time 300msec
Mass range m / z 10-500

<Printability (1)>
A glass epoxy substrate and QFP (package size: 14 mm × 14 mm × 1.0 mm) with a 100-pin 0.5 mm pitch were prepared. A solder resist corresponding to the QFP and an electrode (210 μm × 1,100 μm) are provided on the glass epoxy substrate, and then a 150 μm-thick metal mask having the same pattern as this is used, and each solder paste is printed on a printing machine (product name : SP60P-L, manufactured by Panasonic Corporation), each type was first printed on the substrate as two discarded prints, and then continuously printed on the six substrates to prepare each test substrate. The printing conditions were squeegee speed: 30 mm / second and plate separation speed: 1.0 mm / second.
The difference height in 100 pins (the average height was subtracted from the height of the top of the printed shape) using an image inspection machine (product name: aspire2, manufactured by Koyon Technology Co., Ltd.) for the printed pattern on each test substrate. The number of horns having a value of 180 μm or more was measured. The results are shown in Table 2.

<Printability (2)>
For each test substrate produced with printability (1), the printability of the pattern (whether or not blurring occurs) is as follows using an image inspection machine (product name: aspire2, manufactured by Koyon Technology Co., Ltd.). And evaluated. The results are shown in Table 2.
◎: Very good ○: Good △: Normal ×: Bad

As described above, the solder pastes according to Examples 1 to 7 and Reference Examples 8 and 9 contain a fine pattern by including an ester solvent (B-1) having no hydroxyl group at the terminal in the flux composition. Even when a 150 μm solder mask having a thickness of 10 is used, stable plate release and printability can be ensured. In particular, the flux composition contains the ester solvent (B-1) having two ester bonds, has a fatty acid polyamide structure as the thixotropic agent (D), and the fatty acid has a long-chain alkyl group having 12 to 22 carbon atoms. The solder pastes of Examples 1 to 7 containing the thixotropic agent (D-1) exhibit particularly excellent plate release properties and printability.

Claims (2)

(A) a base resin, (B) a solvent, (C) an activator, and (D) a thixotropic agent,
As the solvent (B), (B-1) includes an ester solvent having no hydroxyl group at the end,
The ester solvent (B-1) has two ester bonds,
The thixotropic agent (D) includes (D-1) a thixotropic agent having a fatty acid polyamide structure and the fatty acid having a long-chain alkyl group having 12 to 22 carbon atoms,
The thixotropic agent (D-1) is the pyrolysis gas chromatography mass spectrometry (heating RoNoboru raising rate: 20 ° C. / min) Ri detected temperature is 480 ° C. der from 450 ° C. to volatilize the maximum peak value by,
The thixotropic agent (D-1) is Taren VA-79 (Kyoeisha Chemical Co., Ltd.) der flux composition characterized Rukoto.   A solder paste comprising the flux composition according to claim 1 and a solder alloy powder.