JP2008302407A - Flux composition for soldering and solder paste composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flux composition for soldering, which allow scattering of flux and solder during fusion of solder to be reduced while maintaining solderability when used in the surface mounting of electronic components on a substrate, and to provide a solder paste composition. <P>SOLUTION: The flux composition for soldering has a melt viscosity of 100-500 mPa s by a B-type viscometer at 200°C. It is preferable that the flux composition contain 30-120 weight parts of polyetherester amide (b) based on 100 weight parts of polyhydric alcohol ester (a) of rosins. The solder paste composition contains solder powder in this flux. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a soldering flux composition (hereinafter sometimes simply referred to as a flux) and a cream solder composition containing the flux composition.

Flux is a soldering material used for soldering and mounting electronic components such as ICs, capacitors, resistors, etc. on printed circuit boards, etc., and is generally a base resin component, activator, solvent, etc. It is comprised from. In the surface mounting of electronic components, the liquid flux used alone with the flux composition, such as spray coating on the solder joints such as printed circuit boards in advance, and the flux composition and the solder powder are kneaded. It is known that it is used as a so-called cream solder composition in the form of a paste (cream).

  As a resin component which is a base used in these liquid flux and cream solder compositions, rosins (rosin or derivatives thereof) are generally used. The reason for its use is that it is excellent in corrosion resistance due to the rosin skeleton, and is excellent in electrical properties such as electrical insulation resistance and dielectric properties. However, rosins have insufficient heat resistance during soldering, and the viscosity also decreases. For this reason, flux and solder are scattered by the gas generated by pyrolysis of rosins, etc., resulting in poor contact due to flux adhering to the electrodes and electrical short circuit (bridge) due to solder scattered between the electrodes of the electronic components. This may cause a significant decrease in product reliability and yield.

  In particular, in high-density mounting with gold-plated terminal parts in the die bonding part, wire bonding part, and soldering peripheral part, the distance between the electrodes is short, so there is a possibility that the solder flux will adhere to the electrodes when scattered. This increases the risk of poor bonding and electrical shorts. In addition, in order to reduce the voids in the solder after soldering, a method of soldering (reflow) in vacuum or reduced pressure is known, but these methods are compared with those under atmospheric pressure. As the amount of gas generated during soldering increases, the scattering of the flux becomes more prominent, and the problems related to the reliability and yield of the above-mentioned products have become apparent.

As a prior art for the purpose of preventing scattering of flux and solder, Patent Document 1 discloses a method in which a polymerized fatty acid polyamide elastomer is added to a flux component in soldering using a soldering iron and solder containing solder. However, unlike solder containing solder, it cannot be applied to a liquid flux or cream solder composition using a solvent, and therefore, establishment of a new measure for reducing solder flux scattering is desired.
Patent Document 2 discloses that a soldering flux composition and a cream solder composition using a rosin and a polyether ester amide resin as resin components exhibit a moisture-proof effect. There is no description about the prevention effect, and further improvement is desired.

JP 2007-69259 A JP 2004-230426 A

The present invention provides a soldering flux composition capable of reducing the amount of flux and solder scattering during soldering while having high soldering performance, and a cream solder composition containing the same. With the goal. In particular, to provide a cream solder composition capable of efficiently performing surface mounting where soldering is performed in a vacuum or under reduced pressure, such as mounting of electronic components having die bonding portions, wire bonding portions, and plating portions that are likely to cause scattering. With the goal.

The present invention has found that the above-mentioned problems can be solved by setting the melt viscosity of the resin component contained in the flux within a predetermined range, and further using a polyhydric alcohol ester of rosin as the resin component. It is a thing.

  That is, this invention is a flux composition for soldering containing the resin component (A) whose melt viscosity by a B-type viscometer at 200 degreeC is 100-500 mPa * s. The soldering flux composition as described above, wherein the resin component (A) contains 30 to 120 parts by weight of a polyether ester amide (b) with respect to 100 parts by weight of the polyhydric alcohol ester (a) of rosins. The soldering flux composition as described above, further comprising at least one selected from the group consisting of a rosin derivative other than the polyhydric alcohol ester (a) of a rosin, an activator, an additive and a solvent. A cream solder composition comprising the soldering flux composition described above and a solder powder (B). A solder paste composition for surface mounting comprising the soldering flux composition described above and a solder powder (B).

According to the present invention, it is possible to obtain a soldering flux composition and a cream solder composition that have high soldering performance and have a reduced amount of solder flux and solder scattering. By using it, the quality and yield are improved in high-density mounting of electronic components and surface mounting of electronic components that are soldered in vacuum or under reduced pressure.

  The soldering flux composition of the present invention contains a resin component (A) having a melt viscosity of 100 to 500 mPa · s as measured by a B-type viscometer at 200 ° C. By using a flux composition whose base resin has a melt viscosity adjusted to the above range, it is possible to prevent solder and flux scattering due to expansion and rupture of gas components caused by thermal deterioration of the flux resin component during solder melting. A reduced flux composition can be obtained.

  When the melt viscosity of the resin component (A) by a B-type viscometer at 200 ° C. is less than 100 mPa · s, the scattering of flux and solder cannot be reduced sufficiently, and when it exceeds 500 mPa · s. There is a problem that solderability is lowered.

Such a resin component (A) is not particularly limited as long as the melt viscosity is in the above range, and may be prepared by using a conventionally known one. Examples include alcohol esters (a) (hereinafter also referred to as component (a)), rosins, rosin esters other than component (a), polyamide resins, polyester resins, phenoxy resins, terpene resins, and other synthetic resins. It is done. Among these, polyether ester amide (b) (hereinafter sometimes referred to as component (b)) is preferable in terms of easy adjustment of the melt viscosity to such a range. Moreover, these can be used 1 type or in combination of 2 or more types.
In particular, as the resin component (A), it is more preferable to use the component (a) and the component (b) in combination. As a result, polyvalent alcohol is reacted with an active carboxyl group of rosins to form a polyvalent ester compound, thereby increasing the thermal stability of rosins and reducing the generation of gas accompanying thermal decomposition during soldering. be able to. In addition, by using together the polyamide ether ester amide (b), the melt viscosity by the B-type viscometer of the resin component (A) can be adjusted in the range of 100 to 500 mPa · s, so it is inevitably generated. It is possible to effectively reduce solder and flux scattering due to the burst of the flux and solder caused by the pyrolysis gas.

As the rosins constituting the component (a), various known natural rosins such as gum rosin, wood rosin, tall oil rosin, polymerized rosin, hydrogenated rosin, disproportionated rosin, unsaturated fatty acid of natural rosin (fumaric acid) And various rosin derivatives such as maleic acid, (meth) acrylic acid) -modified products, and phenol-modified products.

The natural rosins usually have an acid value of about 160 to 190 (preferably 170 to 180) mg KOH / g (according to JIS-K5902; hereinafter abbreviated units), and the softening point is usually about 67 to 177 ° C. It is.

Among the various rosin derivatives, the polymerized rosin contains about 30 to 80% by weight of the resin acid contained in the natural rosins, and is generally about 100 to 300, preferably about 140 to 170. The acid value is a composition having a softening point of usually about 90 to 177 ° C, preferably 100 to 140 ° C. This can be obtained as a commercial product such as “CP-No. 140 (manufactured by Takehira Prefectural Hayashi Sanka Kogyo Co., Ltd.)” or “TX295 (manufactured by Arizona Chemical Co., Ltd.)”. Moreover, the unsaturated fatty acid (fumaric acid, maleic acid, (meth) acrylic acid) modified product of the natural rosins contains a compound formed by adding a unsaturated fatty acid to a natural rosins with Diels-Alder, and as a whole Usually, the acid value is about 20 to 400, preferably about 100 to 300, particularly preferably 200 to 250, and the softening point is usually about 90 to 180 ° C, preferably about 100 to 170 ° C. This can be obtained, for example, as a commercial product (both manufactured by Arakawa Chemical Industries, Ltd.) such as “Pine Crystal KE Series” and “Marquide Series”.
In addition, as rosins, what combined natural rosins and rosin derivatives can also be used suitably.

  The component (a) is an ester compound having excellent thermal stability obtained by reacting the rosin with a polyhydric alcohol, but the polyhydric alcohol is not particularly limited as long as it is divalent or higher. For example, ethylene glycol, diethylene glycol, 1,2-dihydroxypropane, 1,3-dihydroxypropane, 1,2-dihydroxybutane, 1,3-dihydroxybutane, 2,3-dihydroxybutane, neopentyl glycol, 1,4-bis Dihydric alcohols such as hydroxymethyl-cyclohexane, 1,6-hexanediol, octene glycol, polyethylene glycol; glycerol, 1,2,4-butanetriol, triethylene glycol, tripropylene glycol, 3-methylpentane-1, Specific examples include trihydric alcohols such as 3,5-triol and glycerin; and tetrahydric alcohols such as diglycerin and pentaerythritol, but alcohols having a valence of 5 or more may be used. Of these, trihydric alcohol and / or tetrahydric alcohol are preferable from the viewpoint of reducing flux and solder scattering, and glycerin and / or pentaerythritol are particularly preferable.

  (A) The manufacturing method of a component is not specifically limited, Various well-known means can be utilized. Specifically, rosins and polyhydric alcohol are charged into a reaction vessel (preferably under an inert gas stream such as nitrogen or a rare gas), and the system is usually heated to about 150 to 300 ° C. under atmospheric pressure, What is necessary is just to make it react, removing the water to produce | generate out of the system. The charge ratio is preferably an equivalent ratio in which the number of carboxyl groups of the resin acid: number of hydroxyl groups of the polyhydric alcohol is about 1: 1.5 to 1: 0.7. In the reaction, an esterification catalyst may be used. Specifically, for example, acid catalysts such as acetic acid and paratoluenesulfonic acid; alkali metal hydroxides such as lithium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide; calcium oxide, magnesium oxide and the like A metal oxide etc. can be illustrated.

  The component (a) thus obtained is a composition containing an ester compound of usually about 98 to 90% by weight, preferably 95 to 92% by weight, and the acid value is usually about 0.1 to 50, preferably 0.8. About 1 to 25, particularly preferably 1 to 20, the softening point is usually about 70 to 180 ° C, preferably about 80 to 170 ° C, and the hydroxyl value is usually about 0 to 60, preferably 1 to 40. In addition, content (weight%) of this ester compound in (a) component can be determined by measuring by well-known means, such as a gas chromatography, for example. The component (a) is “ester gum AAG”, “same AAL”, “same H”, “pencel A”, “same AD”, “same D-125”, “same D-135”, “same D— 160 ”,“ Superester L ”,“ A-18 ”,“ A-115 ”,“ T-125 ”,“ Pine Crystal KE-359 ”, etc. (all manufactured by Arakawa Chemical Industries, Ltd.) ).

  The component (b) used in the present invention is a resin composed of a polyamide skeleton that is a hard segment and a polyether skeleton that is a soft segment.

The polyamide skeleton is composed of dicarboxylic acid such as sebacic acid and the like, and diamine such as hexamethylenediamine, and the polyether skeleton is composed of polyoxyalkylene glycol such as polyoxyethylene glycol.

The polyamide skeleton is composed of various known linear dicarboxylic acids such as adipic acid, sebacic acid and dodecanedioic acid; various known aromatic dicarboxylic acids such as phthalic anhydride, terephthalic acid and hymic anhydride; and a polymerized fatty acid. Selected from the group consisting of at least one selected and various known linear diamines such as tetramethylenediamine, pentamethylenediamine, hexamethylenediamine; and various known branched polyamines such as diethylenetriamine and triethylenetetramine. It consists of at least one species. The polyether skeleton is composed of polyoxyalkylene glycols such as polyoxyethylene glycol and polyoxypropylene glycol.

As the component (b) used in the present invention, a condensation polymer comprising sebacic acid, tetramethylene diamine and polyoxyethylene glycol; a condensation polymer comprising polymerized fatty acid, hexamethylene diamine and polyoxyethylene glycol, and the like are used as a flux composition. It is preferable because various performances such as solderability are particularly excellent.

Although the molecular weight of (b) component is not specifically limited, 5000-50000 (polystyrene conversion value by a gel permeation chromatography) is preferable from a viewpoint of the ease of adjustment of melt viscosity and ensuring soldering performance.

  The amount of component (a) and component (b) used is preferably 30 to 120 parts by weight of polyetheresteramide (b) per 100 parts by weight of polyhydric alcohol ester (a) of rosins. If the amount of component (B) used relative to 100 parts by weight of component (a) is less than 30 parts by weight, the effect of reducing flux scattering tends to be insufficient, and if the amount used exceeds 120 parts by weight, solder will be used. There is a tendency to deteriorate the attachment. For this reason, the amount of component (b) used is preferably 40 to 100 parts by weight, more preferably 50 to 90 parts by weight.

In addition to the components (a) and (b), rosins other than the component (a) may be used in combination as the resin component (A) contained in the soldering flux composition of the present invention. It improves the function of the flux of cleaning the surface of the lead-free solder powder (removing the oxide film) by the action of the active carboxyl group that they have. Among them, it is preferable to use polymerized rosins and / or the acrylated rosins.
Moreover, you may use together synthetic resins other than (b) component. The synthetic resin may be an epoxy resin, acrylic resin, polyimide resin, polyamide resin (nylon resin), polyester resin, polyacrylonitrile resin, vinyl chloride resin, vinyl acetate resin, polyolefin resin, fluorine resin, or ABS resin. Or what mix | blended two or more can be illustrated. Note that synthetic rubber such as isoprene rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber or nylon rubber, and elastomer such as nylon elastomer or polyester elastomer may be used. These may be used usually in the range of about 0 to 20% by weight with respect to the total solid content weight of the resin component (A).

The flux composition according to the present invention can contain at least one selected from the group consisting of an activator (B), an additive (C) and a solvent (D) in addition to the resin component (A).

  As the activator (B), those usually used for soldering fluxes can be used without any particular limitation. Specifically, an organic acid compound activated in the preheating process of the reflow treatment, a halide activated near the peak temperature, a compound showing activity from the preheat to the peak temperature, or the like can be used. Examples of the organic acid compound include succinic acid, benzoic acid, adipic acid, abietic acid, glutaric acid, palmitic acid, stearic acid, formic acid, and azelaic acid. Examples of the halogen compound include ethylamine hydrochloride, methylamine hydrochloride, ethylamine bromate, diethylamine bromate, methylamine bromate, propenediol hydrochloride, allylamine hydrochloride, 3-amino-1-propene. Examples include hydrochloride, N- (3-aminopropyl) methacrylamide hydrochloride, O-anisidine hydrochloride, n-butylamine hydrochloride, P-aminophenol hydrochloride, and the like. In addition, examples of the activator that can exhibit activity from the preheat to the main heat include quaternary ammonium, lauryltrimethylammonium chloride, and alkylbenzyldimethylammonium chloride. These may be used in combination as appropriate. In addition, content of the activator (B) in a flux is about 0.1 to 10 weight% normally, Preferably it is about 0.1 to 5 weight%, More preferably, it is 0.1 to 3 weight%.

  As the additive (C), various known antioxidants, thixotropic agents and the like can be used. Examples of the antioxidant include tributylamine, tetrabutylammonium bromide, 2,6-di-t-butyl-p-cresol, para-tert-amylphenol, 2,2′-methylenebis (4-methyl-6-tert). -Butylphenol), trans-2,3-dibromo-2-butene-1,4-diol, and the like. Examples of thixotropic agents include castor oil, hydrogenated castor oil, beeswax, carnauba wax, stearamide, hydroxystearic acid ethylenebisamide, and the like. In addition, as additive, “bosatsu (or dry)” or “skinning” (solder ball reacts with the active agent in the flux during the storage of the solder paste, and the viscosity of the paste changes. In order to prevent the skin from becoming hard as it is peeled, or even the viscosity of the whole cream from being lost, etc.) to prevent 3-methyl-1-butyn-3-ol, 3-methyl- 1-pentyn-3-ol, 3,5-dimethyl-1-hexyne-3-ol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,4,7,9-tetramethyl-5 An acetylene alcohol compound such as decyne-4,7-diol and 3,6-dimethyl-4-octyne-3,6-diol (see JP 2000-263281 A) may optionally be used. The content of the additive (C) in the flux is usually about 0.1 to 10% by weight, preferably about 0.1 to 5% by weight, and more preferably 0.1 to 2% by weight. When a thixotropic agent is used as the additive (C), it may be used in an amount of about 3 to 10% by weight. When an acetylenic alcohol compound is used, it is used in an amount of about 0.1 to 5% by weight. Good.

  As the solvent (D), various known solvents that can be used for the flux can be used without particular limitation. Specifically, ethylene glycol monohexyl ether, diethylene glycol monobutyl ether, hexyl glycol, octanediol, ethylhexyl glycol, benzyl alcohol, 1,3-butanediol, 1,4-butanediol 2- (2-n-butoxyethoxy) Alcohols such as ethanol and terpineol; esters such as butyl benzoate, diethyl adipate and 2- (2-n-butoxyethoxy) ethyl acetate; hydrocarbons such as dodecane and tetradecene; N-methyl-2-pyrrolidone and the like Examples of pyrrolidones. In addition, since the melting temperature of lead-free solder is very high as described above, among them, those having a boiling point in the range of about 150 to 300 ° C., preferably 220 to 250 ° C. are preferable. In addition, content of the solvent (D) in a flux is about 20 to 85 weight% normally, Preferably it is about 25 to 85 weight%, More preferably, it is 30 to 80 weight%.

  The flux according to the present invention can be obtained by kneading the base resin (A), the activator (B), the additive (C), and the solvent (D) by a known means. Conditions (temperature, pressure, etc.) at that time are not particularly limited, but examples of the kneading means include a planetary mill.

  The cream solder composition of the present invention is a cream-like solder paste obtained by kneading the flux according to the present invention and various known solder powders by a known mixing means such as a planetary mill.

As solder powder used in the cream solder composition of the present invention, Sn solder powder, Sn-Pb solder powder, Sn-Pb-Ag solder powder, Sn-Pb-Bi solder powder, In-Pb solder powder Pb—Ag solder powder, Sn—Ag solder powder, Sn—Cu solder powder, Sn—Zn solder powder, Sn—Sb solder powder can be exemplified. As the Sn-Ag solder powder, Sn-Ag solder powder, Sn-Ag-Cu solder powder, Sn-Ag-Bi solder powder, Sn-Ag-Cu-Bi solder powder, Sn-Ag-Cu- Examples include In solder powder, Sn-Ag-Cu-S solder powder, and Sn-Ag-Cu-Ni-Ge solder powder.

  Further, the use ratio of the flux and the solder powder is a solid weight ratio, and usually the former: the latter may be about 5:95 to 20:80. In addition, as long as it exists in this range, the said additive (C), a solvent (D), and another additive can further be used arbitrarily.

  Hereinafter, the present invention will be described more specifically through examples and comparative examples, but the present invention is not limited to these examples.

(Preparation of flux composition)
The materials shown below were each charged in a container with the formulation shown in Table 1 and dissolved by heating to about 20 ° C., and then cooled to prepare a flux composition.

Polyether ester amide resin: manufactured by Fuji Kasei Co., Ltd., trade name “TPAE-12” number average molecular weight (gel permeation chromatography, polystyrene conversion value) of 30,000.
Glycerin ester of rosin: Arakawa Chemical Industries, trade name “KE-359”
Hydrogenated rosin: manufactured by Arakawa Chemical Industries, Ltd., trade name “CRW-300”
Solvent: hexyl carbitol (manufactured by Nippon Emulsifier Co., Ltd.)
Activator 1: Diethylamine hydrobromic acid (manufactured by Kishida Chemical Co., Ltd.)
Activator 2: Adipic acid (manufactured by Wako Pure Chemical Industries, Ltd.)
Thixotropic agent: Hardened castor oil (manufactured by Toyokuni Oil Co., Ltd., trade name “Caster Wax”)

(Preparation of cream solder composition)
Solder powder (Sn—Ag—Cu alloy having a particle diameter of 20 to 40 μm, 96.5 wt% / 3 wt% / 0.5 wt%) 89 wt% and 11 wt% of each flux composition prepared above The mixture was stirred to prepare a cream solder composition, and the following evaluation test was performed. The results are shown in Table 1.

(Evaluation test)
(Melt viscosity)
The resin component (A) was measured for the viscosity of the molten resin at 200 ° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.).
(Flux and solder scattering properties)
The solder was melted according to “JISZ3284 Annex 10 Wetting Effect and Dewetting Test”. An unpolished phosphorus deoxidized copper plate was used. Thereafter, the number of flux / solder scattering was counted on the copper plate other than the soldered portion with an optical microscope. In this test, when 10 or more fluxes / solders are scattered, a significant defect may occur in the actual manufacturing process. Therefore, the scattering property was evaluated according to the following criteria.
Judgment criteria follow the following categories.
Good (O): Number of flux / solder scattering is less than 10 Poor (x): Number of flux / solder scattering is 10 or more

(Solderability)
Evaluation was performed according to “JISZ3284 Annex 10 Wetting efficacy and dewetting test”.
Judgment criteria follow the classification of the degree of wetting and spreading of solder metal after soldering.
Good (O): Spreading degree category 2 or higher Poor (x): Spreading degree category 3 or lower

The solder compositions of Examples 1 to 3, in which the polyether ester amide resin and rosin glycerin ester were blended, were excellent in flux and solder scattering results as compared with Comparative Example 1 in which only rosin glycerin ester was blended. And good solderability was maintained.
On the other hand, the solder composition of Comparative Example 2 in which only the polyether ester amide resin was blended had a problem in solderability, although the flux / solder scattering property was good.

Claims (4)

A soldering flux composition containing a resin component (A) having a melt viscosity of 100 to 500 mPa · s as measured by a B-type viscometer at 200 ° C. The soldering flux composition according to claim 1, wherein the resin component (A) contains 30 to 120 parts by weight of a polyether ester amide (b) with respect to 100 parts by weight of a polyhydric alcohol ester (a) of rosins. Furthermore, the flux composition for soldering of Claim 2 containing at least 1 sort (s) chosen from the group which consists of rosin derivatives other than the polyhydric alcohol ester (a) of rosins, an activator, an additive, and a solvent. A solder paste composition comprising the soldering flux composition according to any one of claims 1 to 3 and solder powder.