JP5019057B2 - Solder flux and cream solder - Google Patents

Description

The present invention relates to solder flux and cream solder.

A rosin compound is widely used for the solder flux. In addition to rosin, various rosin compounds such as rosin hydride, disproportionation product and modified product are known. However, in the case of using a rosin compound, there has been a problem that the resin to be selected has poor performance such as thermal stability and electrical insulation. (For example, see Patent Document 1, page 1, left column, line 13 to page 2, upper left column, line 3)

Therefore, as a method for improving heat resistance and electrical insulation, for example, a method of using a distilled and purified product of hydrogenated rosin, disproportionated rosin or polymerized rosin as a rosin resin has been proposed (see Patent Document 1). . Although the electrical insulation can be improved to some extent by this method, the solder ball has not yet been sufficient.

By the way, in recent years, as solder is used in the form of cream solder, suppression of solder balls and improvement in color tone of flux have been demanded. As a method for solving these problems, a method using a reaction product obtained by Diels-Alder reaction of levopimaric acid and acrylic acid has been proposed (see Patent Document 2). According to the method, it was possible to obtain a cream solder having a good color tone, suppressing the generation of solder balls, and having good solderability. The color of the residue was still not sufficient.

JP 59-159298 A JP-A-6-39584

An object of the present invention is to provide a solder flux having good electrical insulation, few solder balls, good color tone of a residue after reflow, and good solderability.

As a result of intensive studies, the present inventors have found that the electrical insulation can be improved by reducing the electrical conductivity of the resin used for the solder flux, and that the above problem can be solved by using a specific rosin derivative. The present invention has been completed.

That is, the present invention provides a 20 wt% ethanol solution having a metal content of 50 ppm or less obtained by hydrogenating an addition reaction product of an α, β-unsaturated carboxylic acid (a) and a rosin (b). The present invention relates to a solder flux containing a rosin derivative (A) having an electrical conductivity of 1.0 μS / cm or less; powder solder and cream solder containing the solder flux.

  According to the present invention, there is provided a resin suitable for solder flux, particularly cream solder, which has good electrical insulation, less solder balls, good color tone of residue after reflow, and good solderability. be able to. In addition, the solder flux of the present invention has excellent heat resistance and good color tone.

The flux of the present invention hydrogenates an addition reaction product of α, β-unsaturated carboxylic acid (a) (hereinafter referred to as component (a)) and rosin (b) (hereinafter referred to as component (b)). Contains a rosin derivative (A) (hereinafter referred to as component (A)) having an electric conductivity of about 1.0 μS / cm or less when the obtained metal content is about 50 ppm or less and a 20 wt% ethanol solution is used. It is characterized by that.

  When the content of the metal contained in the component (A) exceeds 50 ppm, the electric conductivity is 1.0 μS / cm or more, which is not preferable because the electric insulation is lowered. In addition, in this invention, a metal means elements other than a 17 group 18 element, hydrogen, boron, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, and selenium. In addition, the electrical conductivity of the resin solution in which the component (A) is dissolved in ethanol to 20% by weight corresponds to the electrical insulation when used as a solder. This will deteriorate the electrical insulation of the flux. The metal content is a value determined using a wavelength dispersive X-ray fluorescence analyzer ZSX100e (manufactured by Rigaku Denki Co., Ltd.), and the electrical conductivity when a 20 wt% ethanol solution is used is CONDUCTIVITY METER. It is a value determined by (manufactured by Horiba, Ltd.).

In addition, the content of the Group 1 element and the Group 17 element contained in the component (A) is preferably about 20 ppm or less because the electrical conductivity can be lowered, and is preferably 10 ppm or less. Particularly preferred.

(A) As a component used for manufacture of a component, it does not specifically limit, A well-known thing can be used. Specific examples include (meth) acrylic acid, (anhydrous) maleic acid, fumaric acid, (anhydrous) citraconic acid, (anhydrous) itaconic acid and the like. Among these, the use of acrylic acid is preferable because the resin color tone and brittleness become better.

(B) Component (b) used for manufacture of a component is not specifically limited, A well-known thing can be used. Specific examples include raw material rosins such as gum rosin, wood rosin, and tall oil rosin. The component (b) is preferable because the metal can be removed and the resin color tone can be further improved by refining. Although it does not specifically limit as a purification method, Specifically, distillation, recrystallization, extraction etc. are mentioned, for example. In the case of distillation, it is usually selected appropriately in consideration of the distillation time from a temperature range of 200 to 300 ° C. and a pressure of 130 to 1300 Pa. The recrystallization can be carried out, for example, by dissolving the unpurified component (b) in a good solvent, then distilling off the solvent to form a concentrated solution, and adding a poor solvent to this solution. Examples of good solvents include benzene, toluene, xylene, chloroform, lower alcohols having 1 to 3 carbon atoms, ketones such as acetone, and acetates such as ethyl acetate. Examples of poor solvents include n-hexane and n-heptane. , Cyclohexane, isooctane and the like. Further, in the purification, the unpurified component (b) may be made into an alkaline aqueous solution using alkaline water, and the resulting insoluble unsaponified product may be extracted with an organic solvent, and then the aqueous layer may be neutralized.

The reaction between the component (a) and the component (b) can be performed by a known method. Specifically, for example, the components (a) and (b) are mixed and heated at about 150 to 300 ° C. for about 0.5 to 24 hours. Although the usage-amount of (a) component and (b) component is not specifically limited, Usually, (a) component is about 1 mol part or less with respect to 1 mol part of (b) component, Preferably it is 0.05-0. 75 mol parts, particularly preferably 0.10 to 0.70 mol parts are reacted. The modification rate of the rosin derivative with the α, β-unsaturated carboxylic acid is preferably about 30 to 70% because the activity becomes high because the acid value becomes high. If it exceeds 70%, the brittleness of the resin tends to increase. The modification rate is a value calculated from the peak area based on rosin obtained by gel permeation chromatography analysis and the peak area value of the α, β-unsaturated carboxylic acid-modified rosin.

The component (A) used in the present invention can be obtained by hydrogenating the α, β-unsaturated carboxylic acid-modified rosin thus obtained. Hydrogenation is not specifically limited, A well-known method is employable. Specifically, for example, in the presence of a hydrogenation catalyst, usually under a pressure of hydrogen of 1 to 25 MPa, preferably 5 to 20 MPa, about 0.5 to 7 hours, preferably 1 to 5 hours, α, β-depleted. This is carried out by heating a saturated carboxylic acid-modified rosin. As the hydrogenation catalyst, various known catalysts such as supported catalysts such as palladium carbon, rhodium carbon, ruthenium carbon and platinum carbon, metal powders such as nickel and platinum, and iodides such as iodine and iron iodide may be used. it can. The amount of the catalyst used is usually about 0.01 to 5 parts by weight, preferably 0.01 to 3.0 parts by weight with respect to 100 parts by weight of the α, β-unsaturated carboxylic acid-modified rosin. The hydrogenation temperature is about 100 to 300 ° C, preferably 150 to 290 ° C. Hydrogenation is preferably performed so that the hydrogenation rate is about 30 to 60% in order to obtain a resin having good resin color tone and thermal stability and low crystallinity. The hydrogenation rate is a value determined by gas chromatography GC-14A (manufactured by Shimadzu Corporation).

  In the hydrogenated α, β-unsaturated carboxylic acid-modified rosin thus obtained, the catalyst used during the hydrogenation, the metal derived from the catalyst, etc. (particularly, metals of Group 1 and Group 17 elements) remain. Since there exists a tendency, it is preferable to refine | purify further as needed. Purification may be performed by a method such as distillation, recrystallization, extraction or the like. The component (A) thus obtained has a metal content of 50 ppm or less and an electric conductivity of 1.0 μS / cm or less when made into a 20 wt% ethanol solution. Further, the color tone of the component (A) is usually Gardner color 2 or less. In the present invention, the color tone (Gardner color) is determined by taking 10 g of the target resin in a test tube and heating and melting it under a nitrogen stream and color-matching with Gardner color number standard solution manufactured by Kishida Chemical Co., Ltd. It is the value. (Hereinafter, the Gardner color is a value measured by this method.)

  The solder flux of the present invention is characterized by containing the component (A), and further, a flux base resin other than the known component (A), a thixotropic agent, an activator, additives other than these, etc. It may contain.

  As a flux base resin, if it is different from (A) component, it will not specifically limit and a well-known thing can be used. Specific examples include gum rosin, polymerized rosin, hydrogenated rosin, disproportionated rosin, various other rosin derivatives, and synthetic resins such as polyester resin, phenoxy resin, terpene resin, and polyamide resin. In addition, when using flux bases other than (A) component together, it is preferable to reduce the amount of metals, for example by performing the refinement | purification etc. which were mentioned above.

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.

The thixotropic agent is not particularly limited, and known ones can be used. Specifically, for example, hardened castor oil, beeswax, carnauba wax, stearamide, hydroxystearic acid ethylene bisamide and the like can be used.

As an activator, it does not specifically limit but a well-known thing can be used. Specific examples include amine hydrohalides, organic acids, and organic amines.

The additive is not particularly limited as long as it can be usually used for the preparation of a flux, and known additives can be used. Additives such as antioxidants, antifungal agents and matting agents can be contained.

The composition ratio of each component of the flux containing the flux base resin, the solvent, the thixotropic agent, the activator and the specific compound may be appropriately determined according to various uses, but usually about 30 to 75 parts by weight of the flux base resin. The solvent is about 20 to 60 parts by weight, the thixotropic agent is about 1 to 10 parts by weight, and the activator is about 0.1 to 10 parts. The flux of the present invention can be obtained by mixing these components by a known method. The obtained flux component has a melt viscosity at 200 ° C. of about 50 to 500 mPa · s.

The cream solder of the present invention contains solder powder and the soldering flux.

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, as a solder alloy, a conventionally known tin-lead alloy, a solder alloy composition such as a tin-silver alloy and a tin-zinc-based alloy that have been developed as a lead-free solder; , Indium, antimony and the like can be used. Although the usage-amount of each component is not specifically limited, Usually, a solder flux is about 20-5 weight part with respect to 80-95 weight part of solder powder.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples.

Example 1
(1) Purification Acid value 170, softening point (measured by the ring and ball method specified in JIS K5902; hereinafter, softening point is a value measured by the same method) 74 ° C., unrefined Chinese product of color tone Gardner 6 1,000 g of gum rosin and 500 g of xylene were placed in Kolben and dissolved by heating. After that, about 350 g of xylene was distilled off, and then 350 g of cyclohexane was added and cooled to room temperature. When about 100 g of crystals were formed by cooling, the supernatant was transferred to another Kolben and recrystallized at room temperature. Then, the supernatant was removed, washed with 100 g of cyclohexane, and the solvent was distilled off to obtain 700 g of purified rosin. .
(2) Addition reaction The reaction vessel was charged with 660 g of the purified rosin obtained in (1) above and 100 g of acrylic acid, and reacted for 4 hours at 220 ° C. with stirring under a nitrogen stream. Removal gave 720 g of addition reaction product.
(3) Hydrogenation reaction After adding 500 g of the addition reaction product obtained in the above (2) and 5.0 g of 5% palladium carbon (water content 50%) to a 1 liter rotary autoclave and removing oxygen in the system The system was pressurized to 10 MPa with hydrogen, heated to 220 ° C., and subjected to hydrogenation reaction at the same temperature for 3 hours to obtain 460 g of a colorless rosin derivative.
(4) Purification After adding 400 g of the colorless rosin derivative obtained in (3) and 200 g of xylene in Kolben and dissolving them by heating, 150 g of xylene was distilled off, and then 150 g of cyclohexane was added and cooled to room temperature. When about 40 g of crystals were formed by cooling, the supernatant was transferred to another Kolben and recrystallized at room temperature. Then, the supernatant was removed, washed with 20 g of cyclohexane, the solvent was distilled off, the acid value was 245.8, 280 g of a purified colorless rosin derivative having a softening point of 132.0 ° C. and a color tone (Gardner 1 or less) was obtained. Both the metal and group 17 element content in the purified colorless rosin derivative were 0 ppm.

Example 2
100 g of the purified colorless rosin derivative obtained in Example 1 and 1 g of a 1000 ppm aqueous sodium chloride solution were placed in Kolben, remelted, and the purified colorless rosin derivative having an acid value of 245.8, a softening point of 132.0 ° C., and a color tone (Gardner 1) Got. The metal content in the purified colorless rosin derivative was 10 ppm, and the group 1 and group 17 element contents were 20 ppm.

Example 3
100 g of the purified colorless rosin derivative obtained in Example 1 and 7.2 mg of iron oxide (Fe ₂ O ₃ ) were placed in Kolben, remelted, acid value 245.8, softening point 132.0 ° C., color tone (Gardner 1 To obtain a purified colorless rosin derivative. The metal content in the purified colorless rosin derivative was 50 ppm, and the group 1 and group 17 element contents were 0 ppm.

Comparative Example 1
A purified colorless rosin derivative having an acid value of 245.8, a softening point of 132.0 ° C., and a color tone (Gardner 1) was obtained except that the 1000 ppm sodium chloride aqueous solution used in Example 2 was changed to 1.5 g. It was. The metal content in the purified colorless rosin derivative was 15 ppm, and the group 1 and group 17 element contents were 30 ppm.

Comparative Example 2
In Example 3, the same operation was performed except that the amount of iron oxide used was changed to 8.6 mg, and a purified colorless rosin derivative having an acid value of 245.8, a softening point of 132.0 ° C., and a color tone (Gardner 1) was obtained. Obtained. The metal content in the purified colorless rosin derivative was 60 ppm, and the group 1 and group 17 element contents were 0 ppm.

Comparative Example 3
A rosin derivative having an acid value of 247.6, a softening point of 130.5 ° C., and a color tone (Gardner 3) was obtained except that the purification operations (1) and (4) were omitted in Example 1. The metal content in the purified colorless rosin derivative was 54 ppm, and the group 1 and group 17 element contents were 24 ppm.

Performance Evaluation The various rosin derivatives obtained above were evaluated for performance by the following methods. In Comparative Example 4, unpurified rosin having an acid value of 168.0, a softening point of 76.0 ° C., and a color tone (Gardner 7+) was used. The metal content in the unpurified rosin was 92 ppm, and the group 1 and group 17 element contents were 24 ppm.

(Heating stability) 10 g of a sample was put in a test tube having an inner diameter of 1.5 cm and a height of 15 cm, and left to stand in a circulating dryer at 180 ° C. without a lid, and the change in color tone (Gardner) with time was observed. The results are shown in Table 1.

(Electrical conductivity)
20 g of sample and 80 g of ethanol were placed in a 220 ml mayonnaise bottle and dissolved by shaking and stirring. The electrical conductivity of the dissolved 20 wt% ethanol solution was measured by CONDUCTIVITY METER (manufactured by Horiba, Ltd.). The results are shown in Table 1.

(Electrical insulation)
The electrical insulation in the case of solder flux was evaluated from the above electrical conductivity. The results are shown in Table 1.
A: Electrical conductivity of 0.5 μS / cm or less B: Electrical conductivity of more than 0.5 μS / cm to 1.0 μS / cm or less X: Electric conductivity of more than 1.0 μS / cm

(Flux preparation)
50 parts of Examples 1 to 3 and Comparative Examples 1 to 4, 45 parts of diethylene glycol monohexyl ether, and 5 parts of 12-hydroxystearic acid ethylene bisamide were charged in a container, dissolved by heating, and then cooled to prepare a flux composition. did.

(Preparation of cream solder)
Cream by stirring 90 parts of solder powder (Sn—Ag—Cu alloy having an average particle diameter of 5 to 20 μm, 96.5 wt% / 3 wt% / 0.5 wt%) and 10 parts of the flux prepared above A solder composition was prepared.

(Evaluation of cream solder)
(Solderability)
Evaluation was performed in accordance with “JIS Z3284 Annex 10 Wetting Efficacy and Dewetting Test”. The results are shown in Table 1.
Judgment criteria follow the extent of spread.
Good (O): Spread degree category 1 or 2
Defect (x): Spreading degree category 3 or 4

(Solder ball)
Evaluation was performed in accordance with “JIS Z3284 Annex 11 Solder Ball Test”.
Judgment criteria follow the following categories.
Very good (◎): Less than 5 solder balls are good (◯): 5 or more and less than 10 solder balls are defective (x): 10 or more solder balls The test results are shown in Table 1.

(Color tone of residue after reflow)
The degree of coloring of the residue on the substrate after the solderability test was visually evaluated. The results are shown in Table 1.
○: Colorless and transparent Δ: Slightly colored ×: Colored

Claims (7)

The electric conductivity when the metal content obtained by hydrogenating the addition reaction product of α, β-unsaturated carboxylic acid (a) and rosin (b) is 50 ppm or less and a 20 wt% ethanol solution is 1 Solder flux containing rosin derivative (A) which is 0.0 μS / cm or less. The solder flux according to claim 1, wherein the content of the Group 1 element and the Group 17 element contained in the rosin derivative (A) is 20 ppm or less. The solder flux according to claim 1 or 2, wherein the rosin derivative (A) has an α, β-unsaturated carboxylic acid modification rate of 30 to 70%. The solder flux according to any one of claims 1 to 3, wherein the rosin derivative (A) has a hydrogenation rate of 30 to 60%. The solder flux according to any one of claims 1 to 4, wherein the color tone of the rosin derivative (A) is Gardner color 2 or less. Cream solder containing solder powder and the solder flux according to any one of claims 1 to 5. The cream solder according to claim 6, wherein the solder powder is a lead-free solder powder.