JP2010137283A - Flux composition for lead-free solder and lead-free solder paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flux composition for lead-free solder, by which heating slump can be suppressed even at 180°C when it is generated by a solvent or fluid resin in solder paste in preheating the solder paste, and by which superior wettability can be manifested when halogenated compound more effective than organic acid for the solder wettability is extremely reduced (≤0.09 wt.% in terms of chlorine amount and bromine amount, with their total ≤0.15 wt.%). <P>SOLUTION: The flux composition for lead-free solder is used which contains (A) polyamide resin with a melting point ≥200°C and (B) rosin esters (B1) and/or polymerized rosin (B2) and which has an acid number of the flux composition 40 to 100 mg-KOH/g. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a flux composition for lead-free solder and a lead-free solder paste.

A printed circuit board on which electronic components are mounted is used in electronic equipment, but soldering is usually performed to fix a capacitor, a resistor, and the like to the printed circuit board for electrical connection. In order to solder an electronic component to a printed circuit board, usually, a solder paste is printed on the printed circuit board, and then a chip-type electronic component is placed on the printed solder, preheated at around 180 ° C., and preheated. Thereafter, a so-called reflow soldering method is performed in which the solder paste is melted and soldered by further heating to around 240 ° C. In recent years, a reflow soldering method having a batch heating method with excellent productivity is often used due to the miniaturization of electronic components.

In recent years, surface mounting on a printed circuit board is in the direction of higher density, and it is minute and lightweight, and for example, a large number of 1608 chips (1.6 mm in length and 0.8 mm in width) are used. However, recent electronic components have been further reduced in size, and microchips such as 0402 (0.4 mm in length, 0.2 mm in width) have come to be used in electrical equipment such as mobile phones and flat-screen TVs. . For this reason, when the solder paste is screen-printed, the mask opening becomes smaller as the chip size is reduced. Therefore, to achieve good printing, it is necessary to pulverize the solder metal.

However, the solder paste has a problem of so-called drooling (heating dripping), in which a screen-printed coating film is fluidized during preheating, and the shape at the time of coating cannot be maintained and flattened. Especially in the recent soldering with a narrow pitch of printed circuit boards on which the above-mentioned small chips and electronic components with fine lead intervals are mounted at high density, the adjacent coating film protrudes from a predetermined coating position due to its drooling property. In contact with. When this is heated as it is and soldered, a solder bridge, which is a bridge of solder, is formed between the solder lands, and there is a problem that the circuit is short-circuited. In addition, in order to achieve high-density mounting, the pulverized solder particles are likely to be washed away by a solvent contained in the solder paste or a resin having fluidity, so that there is a problem that heating dripping is more likely to occur. Furthermore, if the coating film protrudes from a predetermined position, a so-called small solder ball is formed on the side of the chip part after melting, and the solder ball falls off due to vibration or the like, and the circuit is short-circuited or between the soldered lands. Reduce the insulation resistance. As described above, when the circuit is short-circuited or the insulation resistance is lowered, problems such as deterioration of the electrical reliability of the circuit occur. As a method for solving such a problem, for example, a method using a specific polyethylene glycol-polypropylene glycol-polyethylene glycol block polymer has been proposed (Patent Document 1). According to this method, in the preheating that is heated to around 150 ° C., the heating dripping can be improved, but the higher temperature preheating may induce the heating dripping, so that it could not cope with the reflow of the high temperature preheating. .

  In recent years, when waste containing halogen compounds is incinerated, dioxins may be generated. Therefore, product development that does not contain halogen compounds is progressing, and there is a need for solders that do not contain halogen compounds as much as possible. It is getting to be. In general, a flux composition in which the bromine amount or the chlorine amount is 0.09% by weight or less, or the total amount of chlorine and bromine is 0.15% by weight or less is considered a halogen-free flux.

  However, the solder paste uses a halogen compound for the cleaning action of reducing oxides on the solder surface and land surface and removing the oxide film during solder joining. May reduce the cleaning action and cause solder metal wetting failure. When wetting failure occurs, heating dripping and solder balls are likely to occur.

JP 2002-336993 A

The main object of the present invention is to provide a solder paste composition and a reflow soldering method that have improved drooping properties during preheating in a reflow soldering process, and even when no halogen compound is contained, the electrode An object of the present invention is to provide a solder flux composition having a good cleaning action for removing an oxide film on a metal or solder metal surface.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a specific polyamide resin and a specific rosin resin and further adjusting the acid value of the flux. The present invention has been completed.

  That is, the present invention comprises (A) a polyamide resin having a melting point higher than 200 ° C. and (B) rosin ester (B1) and / or polymerized rosin (B2), and the flux composition has an acid value of 40 mgKOH / g. The present invention relates to a lead-free solder flux composition of 100 mgKOH / g or less; a lead-free solder paste containing the flux composition.

ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of a solder bridge and a solder ball can be prevented by improving the dripping property at the time of preheating of the reflow soldering process in the solder paste of fine powder specifications. As a result, it is possible to provide a solder paste composition that can further reduce soldering failure due to a short circuit in a microchip component. Further, the solder flux composition of the present invention is a halogen-free flux composition in which the bromine content or the chlorine content is 0.09% by weight or less, or the total of the chlorine content and the bromine content is 0.15% by weight or less. However, it also has an excellent cleaning effect.

It is the evaluation piece which evaluated the lead-free solder paste obtained in Examples 1-10 based on JIS Z 3284 Annex 7. It is the evaluation piece which evaluated the lead-free solder paste obtained by Comparative Examples 1-6 based on JISZ3284 appendix 7. FIG.

  The flux composition for lead-free solder of the present invention comprises (A) a polyamide resin having a melting point higher than 200 ° C. (hereinafter referred to as “component (A)”) and (B) rosin esters (B1) (hereinafter referred to as “component (B1)”. ) And / or polymerized rosin (B2) (hereinafter referred to as component (B2)) (hereinafter referred to as component (B1) and / or (B2) as component (B)), and the acid value of the flux composition Is 40 mgKOH / g or more and 100 mgKOH / g or less.

  (A) component used by this invention will not be specifically limited if melting | fusing point is higher than 200 degreeC, A well-known thing can be used. When the melting point of the polyamide resin is 200 ° C. or lower, the effect of suppressing heating dripping becomes weak, which is not preferable. Examples of such polyamide resins include polyamide 6 (melting point 225 ° C.), polyamide 66 (melting point 268 ° C.), D22 (melting point 220 ° C.) manufactured by Daicel Evonik Co., Ltd., and Allen (melting point 320) manufactured by Mitsui Chemicals, Inc. ° C), Kuraray Co., Ltd. Genesta (melting point 306 ° C), Mitsubishi Engineering Plastics Co., Ltd. Reny (nylon MXD6 (melting point 243 ° C)), and the like. In addition, melting | fusing point is the value computed from the peak temperature of the endothermic reaction performed when a polyamide is heated using a DSC (differential scanning calorimetry) apparatus.

  Although the usage-amount of (A) component is not specifically limited, It is preferable to set it as 1 to 5 weight% of the whole flux composition, and it is more preferable to set it as 1.5 to 4 weight%. When the content is 1% by weight or more, the effect of suppressing heating dripping is remarkably improved, and when the content is 5% by weight or less, the viscosity of the solder paste can be appropriately maintained, so that the printability is improved.

  The component (B) used in the present invention is a component containing the component (B1) and / or the component (B2). Component (B1) can be obtained by reacting rosin (b1) (hereinafter referred to as component (b1)) with alcohol (b2).

The component (b1) used in preparing the component (B1) is a natural rosin such as gum rosin, wood rosin, tall oil rosin, or modified, hydrogenated, disproportionated to the natural rosin, which will be described later. Examples thereof include rosin derivatives obtained by adding at least one of various known operations such as polymerization. In addition, when combining this well-known operation with two or more, the order is not specifically limited.

Modification is usually performed using unsaturated carboxylic acids or phenols. Examples of unsaturated carboxylic acids used for modification include (anhydrous) maleic acid, fumaric acid, (anhydrous) itaconic acid, (anhydrous) citraconic acid, and (meth) acrylic acid. As the unsaturated carboxylic acid modification, a known method can be adopted. Specifically, for example, natural rosins and unsaturated carboxylic acids may be reacted at about 150 ° C. to 300 ° C. for about 1 hour to 24 hours. In addition, although the usage-amount of each component is not specifically limited, For example, it is about 0.1-20 weight part of unsaturated carboxylic acids with respect to 100 weight part of natural rosins. Examples of the phenols used for modification include phenol and alkylphenol. A known method can be adopted as the phenol modification. Specifically, for example, natural rosins and phenols may be reacted at about 150 ° C. to 300 ° C. for about 1 hour to 24 hours. In addition, although the usage-amount of each component is not specifically limited, For example, it is about 0.1-50 weight part of phenols with respect to 100 weight part of natural rosins.

  Hydrogenation is not particularly limited, and may be carried out by a known method. Usually, in the presence of a known hydrogen source, a hydrogenation catalyst may be used as necessary, and the reaction may be performed at about 0.1 MPa to 30 MPa. . Examples of the hydrogen source include lithium aluminum hydride and the like in addition to hydrogen gas, and examples of the hydrogenation catalyst include Raney nickel and palladium carbon.

  The disproportionation may be carried out by a known method. For example, the reaction may be carried out at normal pressure using a disproportionation catalyst in the presence of a known hydrogen source.

(B1) Component (b2) used when preparing component includes monovalent alcohols such as methanol, ethanol and propanol, divalent alcohols such as ethylene glycol, diethylene glycol, propylene glycol and neopentyl glycol, and glycerin. , Trivalent alcohols such as trimethylolethane and trimethylolpropane, tetravalent alcohols such as pentaerythritol and diglycerin, and hexavalent alcohols such as dipentaerythritol.

(B1) component, for example, (b1) component and (b2) component are added in the presence or absence of an organic solvent and, if necessary, an esterification catalyst such as sulfuric acid or paratoluenesulfonic acid is added. About 1 hour to 8 hours, the heat dehydration reaction is performed. When using a solvent, it is preferable to use a hydrocarbon solvent.

In addition, although the usage-amount of (b1) component and (b2) component is not specifically limited, Usually, the quantity which has a hydroxyl group about 1 time equivalent-about 2.5 times equivalent with respect to the carboxyl group equivalent of (b1) component. It is preferable to use the component (b2).

The softening point of the component (B1) thus obtained is not particularly limited, but it is usually preferably about 90 ° C to 110 ° C. As the component (B1), one kind of these may be used alone, or several kinds may be mixed and used.

As the component (B2), one obtained by polymerizing the component (b1) described above or a product obtained by polymerizing and hydrogenating the component can be used. As a method for polymerizing the component (b1), a known method can be employed. Specifically, the natural rosins described above are heated at a temperature of about 40 ° C. to 160 ° C. for 1 hour to 5 hours in a solvent such as toluene and xylene containing a catalyst such as sulfuric acid, hydrogen fluoride, aluminum chloride, and titanium tetrachloride. For example, a method of reacting for about an hour.

Although the usage-amount of (B) component is not specifically limited, It is preferable to set it as about 8 to 40 weight% of the whole solder flux composition. When the amount is 8% by weight or more, the effect of suppressing heating dripping is remarkably improved, and when the amount is 40% by weight or less, the viscosity in the case of a solder paste can be appropriately maintained, so that the printability is improved. In addition, when only the component (B1) is used, the amount of the component (B1) is 8% to 40% by weight. When only the component (B2) is used, the amount of the component (B2) It is especially preferable to set it as 20 to 40 weight%.

  In addition, (C) rosins (henceforth (C) component) whose acid value is 140 mgKOH / g-240 mgKOH / g can be added to the solder flux composition of this invention. As the component (C), the component (b1) having an acid value of about 140 mgKOH / g to 240 mgKOH / g can be used. In addition, these may be used individually by 1 type and may be used in mixture of 2 or more types. As the component (C), it is preferable to use an acrylated rosin, a hydrogenated rosin, a disproportionated rosin, or a polymerized rosin because of good compatibility with the polyamide resin described above.

  Although the usage-amount of (C) component is not specifically limited, Usually, it is preferable to set it as about 10 to 40 weight% of the whole flux. The content of 10% by weight or more is preferable because the compatibility of polyamide with rosin is improved. Moreover, since the viscosity at the time of setting it as a solder paste can be maintained moderately by setting it as 40 weight% or less, printability improves. In addition to the component (A), the component (B) and the component (C) used as necessary, a known additive or the like can be used for the flux composition of the present invention. Examples of the additive include a solder flux base resin, an antioxidant, a solvent, a thixotropic agent, an activator, a plasticizer, and other additives.

  Examples of the base resin for solder flux include polyester resins, phenoxy resins, terpene resins, and polyamide resins other than the component (A). The amount of use in the case of using other base resin for flux is not particularly limited, but is usually about 1% to 10% by weight of the total amount of flux.

The antioxidant is not particularly limited, and a known product can be used. Specific examples include 2,6-di-tert-butyl-p-cresol, para-tert-amylphenol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) and the like. Although the usage-amount of antioxidant is not specifically limited, Usually, it is about 0.5 to 1 weight% of the whole flux amount.

The solvent is not particularly limited, and known solvents can be used. Specifically, alcohols such as ethanol, n-propanol, isopropanol and isobutanol, glycol ethers such as butyl carbitol and hexyl carbitol, esters such as isopropyl acetate, ethyl propionate, butyl benzoate and diethyl adipate And hydrocarbons such as n-hexane, dodecane, and tetradecene. In addition, although the usage-amount of a solvent is not specifically limited, Usually, it is about 20 to 40 weight% of the whole flux amount.

The thixotropic agent is not particularly limited, and known ones can be used. Specific examples include hardened castor oil, beeswax, carnauba wax, stearamide, hydroxy stearic acid ethylene bisamide, and the like. Although the usage-amount of a thixotropic agent is not specifically limited, Usually, it is about 3 to 10 weight% of the whole amount of flux.

As an activator, it does not specifically limit but a well-known thing can be used. Specific examples include amine hydrohalides, organic acids, organic halogens, and organic amines. Although the usage-amount of an activator is not specifically limited, Usually, it is 3 weight%-10 weight% of the whole flux. By adjusting the content of the halogen compound contained in the activator so that the bromine amount or the chlorine amount is 0.09% by weight or less, or the total of the chlorine and bromine amounts is 0.15% by weight or less. It can be set as a halogen free flux composition.

It does not specifically limit as a plasticizer, A well-known thing can be used. Specific examples include carboxylic acid esters such as dioctyl phthalate and dioctyl adipate. Although the usage-amount of a plasticizer is not specifically limited, Usually, it is 5 to 10 weight% of the whole amount of flux.

  Other additives are not particularly limited as long as they can be usually used for the preparation of a flux, and known ones can be used. Additives such as antifungal agents and matting agents can be contained.

  A lead-free solder paste can be prepared by adding solder powder or the like to the solder flux composition thus obtained.

The alloy composition of the solder powder used in the present invention is not particularly limited, and various known ones can be used. For example, a solder alloy composition such as a tin-silver alloy and a tin-zinc alloy that has been developed as a lead-free solder; and a solder alloy obtained by adding copper, bismuth, indium, antimony, or the like to the solder alloy can be used. Moreover, as an average powder particle diameter, the powder of about 1-50 micrometers normally, More preferably, less than 25 micrometers can be used.

Although the usage-amount of each component is not specifically limited, Usually, it is preferable that a lead-free solder paste contains about 80% to 95% by weight of solder powder and about 5% to 20% by weight of solder flux.

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated in detail, this invention is not limited to these. In addition, melting | fusing point measurement was measured using Seiko Electronics Co., Ltd. DSC220C, and the acid value measurement of the flux was performed based on JISZ3197. In addition, printability, evaluation of heating drool is JIS Z 3284
In accordance with Annexes 5 and 7, the printability was blotted with continuous 20-sheet printing, with no blurring, and with blurring or blurring with x. Regarding the heating soot, those that achieved 0.2 were rated as ◯, and those other than that were rated as x.

Example 1
Polyamide resin (D22, manufactured by Daicel Evonik Co., Ltd., melting point 220 ° C.) 2% by weight, glycerin ester of rosin (produced by Arakawa Chemical Co., Ltd.) and acrylated rosin (produced by Arakawa Chemical Co., Ltd., acid value) 238 mgKOH / g) was 11% by weight and 36.8% by weight, respectively, 36.5% by weight of solvent (HeDG, manufactured by NOF Corporation), activator (Tokyo Kasei Co., Ltd., 0.1% by weight of adipic acid) 1,4-cyclohexanedicarboxylic acid 2% by weight, sebacic acid 2% by weight, Aldrich Co., Ltd. trans-2,3-dibromo-1,4-butanediol 0.1% by weight, Lion Co., Ltd. Armin 2HT 3% by weight), thixotropic agent (MAWAXO, manufactured by Kawaken Fine Chemical Co., Ltd.) 6% by weight, antioxidant (Irganox 1010, manufactured by Ciba Japan Co., Ltd.) 0 .5 wt% was mixed to prepare a lead-free solder flux composition. The amount of bromine contained in this flux composition was 0.07% by weight and the amount of chlorine was not more than 0.01% by weight, as measured by combustion ion chromatography (AQF-100, manufactured by Dia Instruments, ICS-3000, manufactured by Dionex). The acid value of the flux was 49 mgKOH / g. Solder powder having an average powder particle size of 10 to 25 μm and an alloy composition of Sn96.5 wt% -Ag 3.0 wt% -copper 0.5 wt% (Yamaishi Metal Co., Ltd.) Was used to prepare a lead-free solder paste. The lead-free solder paste thus obtained was evaluated according to JIS Z 3284 Annexes 5 and 7. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 2
In Example 1, glycerin ester of rosin and acrylated rosin were polymerized rosin (Arakawa Chemical Industries, Ltd., acid value 151 mgKOH / g), 21.9% by weight, hydrogenated rosin (Arakawa Chemical Industries, Ltd., acid value) 170 mgKOH / g) 20.9 wt%, lead was used in the same manner as in Example 1 except that 5 wt% of a plasticizer (CRODAMOL IPD Co., Ltd. CRODA) was used and the acid value of the flux was 94 mgKOH / g. A free solder paste was obtained. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 3
In Example 1, glycerin ester of rosin and acrylated rosin were acrylated rosin (manufactured by Arakawa Chemical Industries, Ltd., acid value 238 mg KOH / g), 30% by weight, glycerin ester of rosin (manufactured by Arakawa Chemical Industries, Ltd.) 18 wt. %, Polyamide resin (D22, manufactured by Daicel Evonik Co., Ltd., melting point 220 ° C.) 1.8% by weight, and a lead-free solder paste was obtained in the same manner as in Example 1 except that the acid value of the flux was 94 mgKOH / g. It was. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 4
In Example 1, glycerin ester of rosin and acrylated rosin were acrylated rosin (manufactured by Arakawa Chemical Industry Co., Ltd., acid value 238 mg KOH / g), 22.8% by weight, rosin pentaerythritol ester (manufactured by Arakawa Chemical Industries, Ltd.) A lead-free solder paste was obtained in the same manner as in Example 1 except that the content was 22 wt%, the solvent HeDG (manufactured by Nippon Oil & Fats Co., Ltd.) 39.5 wt%, and the acid value of the flux was 78 mgKOH / g. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 5
In Example 1, the glycerin ester of rosin and the acrylated rosin were converted to acrylated rosin (Arakawa Chemical Industries, Ltd., acid value 238 mg KOH / g), 38.8% by weight, glycerin ester of rosin (Arakawa Chemical Industries, Ltd.) 8.05% by weight, solvent (HeDG, manufactured by NOF Corporation) 39.55% by weight, D22 (produced by Daicel Evonik) 3% by weight, sebacic acid (produced by Tokyo Chemical Industry Co., Ltd.) 1% %, Adipic acid and 1,4-cyclohexanedicarboxylic acid were not added, and a lead-free solder paste was obtained in the same manner except that the acid value of the flux was 98 mgKOH / g. The composition table tested in the same manner as in the Examples using this lead-free solder paste and the acid value of the flux composition are shown in Table 1, and the evaluation results of printability and heating dripping are shown in Table 3 and FIG.

Example 6
In Example 1, glycerin ester of rosin and acrylated rosin were polymerized rosin (Arakawa Chemical Industries, Ltd., acid value 151 mgKOH / g), 21.9% by weight, hydrogenated rosin (Arakawa Chemical Industries, Ltd., acid value) 170 mgKOH / g) 20.9 wt%, 5 wt% plasticizer (CRODAMOL IPD Co., Ltd. CRODA), 2 wt% polyamide resin (Toyobo Co., Ltd., T802 melting point 220 ° C) A lead-free solder paste was obtained in the same manner as in Example 1 except that the acid value of the flux was 94 mgKOH / g. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 7
In Example 1, glycerin ester of rosin and acrylated rosin were polymerized rosin (Arakawa Chemical Industries, Ltd., acid value 151 mgKOH / g), 21.9% by weight, hydrogenated rosin (Arakawa Chemical Industries, Ltd., acid value) 170 mgKOH / g) 20.9% by weight, 5% by weight of plasticizer (CRODAMOL IPD Co., Ltd. CRODA), 2% by weight of polyamide resin (Toyobo Co., Ltd., T662, good point 260 ° C.) A lead-free solder paste was obtained in the same manner as in Example 1 except that the acid value of the flux was 94 mgKOH / g. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 8
In Example 1, the glycerin ester of rosin and the acrylated rosin were acrylated rosin (Arakawa Chemical Industries, Ltd., acid value 238 mgKOH / g) 15% by weight, rosin glycerin ester (Arakawa Chemical Industries, Ltd.) 45% %, The solvent HeDG (manufactured by Nippon Oil & Fats Co., Ltd.) 24.25% by weight, and a lead-free solder paste was obtained in the same manner as in Example 1 except that the acid value of the flux was 41 mgKOH / g. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 9
In Example 1, the glycerin ester of rosin and the acrylated rosin were polymerized rosin (manufactured by Arakawa Chemical Industries, Ltd., acid value 151 mgKOH / g), 18.9% by weight, hydrogenated rosin (manufactured by Arakawa Chemical Industries, Ltd., acid value) 170 mgKOH / g) 19.9% by weight, solvent HeDG (manufactured by NOF Corporation) 37.45% by weight, polyamide resin (D22, manufactured by Daicel Evonik Co., Ltd., melting point 220 ° C.) 5% by weight, plasticizer ( A lead-free solder paste was obtained in the same manner as in Example 1 except that 5% by weight of CRODAMOL IPD (manufactured by CRODA) was used and the acid value of the flux was 85 mgKOH / g. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Example 10
In Example 1, the glycerin ester of rosin (Arakawa Chemical Industries, Ltd.) 37.5% by weight, polyamide resin (D22, manufactured by Daicel Evonik Co., Ltd., melting point 220 ° C.) 1.3% by weight and the acid value of the flux A lead-free solder paste was obtained in the same manner as in Example 1 except that the concentration was 48 mgKOH / g. Table 1 shows the acid values of the composition table and the flux composition, and Table 3 and FIG.

Comparative Example 1
In Example 1, glycerin ester of rosin and acrylated rosin are glycerin ester of rosin (Arakawa Chemical Industries, Ltd.), 10% by weight, acrylated rosin (acid value 238 mgKOH / g, Arakawa Chemical Industries, Ltd.) 37. A lead-free solder paste was obtained in the same manner as in Example 1 except that the acid value of the flux was 113 mgKOH / g with 8% by weight. Table 2 shows the acid values of the composition table and the flux composition, and Table 4 and FIG.

Comparative Example 2
In Example 1, glycerin ester of rosin and acrylated rosin were polymerized rosin (Arakawa Chemical Industries, Ltd. acid value 151 mgKOH / g), 10% by weight, acrylated rosin (Arakawa Chemical Industries, Ltd. acid value 238 mgKOH / g) A solder paste was obtained in the same manner as in Example 1 except that 37.8% by weight and the acid value of the flux was 127 mgKOH / g. Table 2 shows the acid values of the composition table and the flux composition, and Table 4 and FIG.

Comparative Example 3
In Example 1, the glycerin ester of rosin and the acrylated rosin were converted to acrylated rosin (acid value 238 mg KOH / g, manufactured by Arakawa Chemical Industries, Ltd.) 22.8% by weight, glycerin ester of rosin (produced by Arakawa Chemical Industries, Ltd.) 25 Example 1 except that the polyamide resin (PA-30, manufactured by Fuji Kasei Kogyo Co., Ltd., melting point 184 ° C.) is 2% by weight and the acid value of the flux is 80 mg KOH / g. The lead-free solder paste was obtained as shown in Table 2. The acid values of the composition table and the flux composition are shown in Table 2, and the evaluation results of printability and heating dripping are shown in Table 4 and FIG.

Comparative Example 4
In Example 1, the glycerin ester of rosin and the acrylated rosin were converted to acrylated rosin (acid value 238 mg KOH / g, manufactured by Arakawa Chemical Co., Ltd.) 22.8% by weight, glycerin ester of rosin (produced by Arakawa Chemical Co., Ltd.) 27 A lead-free solder paste was obtained in the same manner as in Example 1 except that the weight percentage was not changed, polyamide was not added, and the acid value of the flux was 77 mgKOH / g. Table 2 shows the acid values of the composition table and the flux composition, and Table 4 and FIG.

Comparative Example 5
In Example 1, the glycerin ester of rosin and the acrylated rosin were acrylated rosin (acid value 238 mg KOH / g, manufactured by Arakawa Chemical Industries, Ltd.) 38.8% by weight, glycerin ester of rosin (produced by Arakawa Chemical Industries, Ltd.) 10 .3% by weight, polyamide resin (D22, manufactured by Daicel Evonik Co., Ltd., melting point 220 ° C.) 0.7% by weight, and lead-free solder in the same manner as in Example 1 except that the acid value of the flux was 118 mgKOH / g A paste was obtained. Table 2 shows the acid values of the composition table and the flux composition, and Table 4 and FIG.

Comparative Example 6
In Example 1, the glycerin ester of rosin and the acrylated rosin except for the glycerin ester of rosin, respectively, were acrylated rosin (acid value 238 mgKOH / g, manufactured by Arakawa Chemical Co., Ltd.), and the acid value of the flux was 135 mgKOH / A lead-free solder paste was obtained in the same manner as in Example 1 except that g was used. Table 2 shows the acid values of the composition table and the flux composition, and Table 4 and FIG.

From the results of Tables 3 and 4, it is clear that when the solder flux of the present invention is used, the fluidity of the flux at the time of reflow is lowered and the wetting is improved. In addition, even when the composition is the same, it is clear that when a polyamide having a melting point lower than 200 ° C. is used, there is no effect of suppressing heating.

Claims (7)

(A) a polyamide resin having a melting point higher than 200 ° C. and (B) a rosin ester (B1) and / or a polymerized rosin (B2), and the acid value of the flux composition is 40 mgKOH / g or more and 100 mgKOH / g or less A certain lead-free solder flux composition. The flux composition for lead-free solder according to claim 1, wherein the amount of bromine or chlorine contained is 0.09% by weight or less, or the total amount of chlorine and bromine is 0.15% by weight or less. The flux composition according to claim 1 or 2, wherein (B) the rosin ester (B1) and / or the polymerized rosin (B2) is contained in an amount of 8% by weight to 40% by weight based on the entire flux composition. The flux composition for lead-free solder according to any one of claims 1 to 3, comprising (A) at least 1 wt% to 5 wt% of a polyamide resin having a melting point higher than 200 ° C. (C) The lead-free solder flux composition according to any one of claims 1 to 4, comprising 10 to 40% by weight of rosins having an acid value of 140 mgKOH / g to 240 mgKOH / g. A lead-free solder paste containing the flux composition for lead-free solder according to any one of claims 1 to 5. The lead-free solder paste according to claim 6, wherein a solder powder having an average powder particle size of less than 25 µm is used.

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