WO2007034758A1

WO2007034758A1 - Soldering flux, cream solder, soldering method, food container, and electronic component

Info

Publication number: WO2007034758A1
Application number: PCT/JP2006/318421
Authority: WO
Inventors: Kimio Yamakawa; Katsutoshi Mine
Original assignee: Nihon Handa Co., Ltd.
Priority date: 2005-09-20
Filing date: 2006-09-15
Publication date: 2007-03-29
Also published as: TW200730290A; JP4322948B2; JPWO2007034758A1

Abstract

[PROBLEMS] To provide a flux wherein a flux residue formed after soldering can be removed readily by washing with water and the waste liquid can be biodegraded readily in the natural environment and which is harmless to a human or animal body, a cream solder which causes little air pollution by lead, a soldering method and others. [MEANS FOR SOLVING PROBLEMS] A soldering flux comprising (A) water, (B) (b1) a reductive organic compound or phenolic anti-oxidative agent which is soluble in water, can be biodegraded readily and is composed of a carbon atom, a hydrogen atom and an oxygen atom, or (b-2) an alkaline metal salt of a reductive organic acid which is soluble in water, can be biodegraded readily and is composed of a carbon atom, a hydrogen atom and an oxygen atom and (C) a thixotropic agent which is soluble in water and can be biodegraded readily; a cream solder comprising the soldering flux and (D) a lead-free solder particle; and a soldering method using the cream solder.

Description

Specification

Soldering flux, cream solder, soldering method, food containers and electronic components

Technical field

[0001] The present invention is excellent in soldering flux and solderability that are easy to wash with water after soldering and biodegradable in the natural environment, and the flux residue is easy to wash with water after soldering and easy to decompose in the natural environment. The present invention relates to a cream solder, a method of soldering a metal member using the cream solder, and a food container or an electronic component having a metal member soldered using the cream solder.

Background art

Conventional power Soldering by means of cream solder (also called solder paste) has been frequently used for mounting electronic elements, electronic components, etc. on printed boards and circuit boards. Conventional cream solder contains rosin-based flux and organic solvent, and rosin-based residue after soldering greatly affects the reliability of electronic equipment, so it is necessary to clean the residual flux after soldering is there. For this purpose, volatile organic solvents such as isopropyl alcohol and chlorinated hydrocarbons are often used as cleaning agents.

[0003] However, in recent years, it has been requested to reduce the use of volatile organic solvents (VOC) from the viewpoint of environmental protection. To meet this demand, volatile organic solvents such as isopropyl alcohol are also used for flux residues. Water-soluble flutters that can be washed with water without requiring washing with a solvent have been proposed (Patent Documents 1 and 2). Also, cream solder composed of lead-containing solder powder and water-soluble flux has been proposed (Patent Documents 3 and 4).

[0004] However, the flux of Patent Document 1 contains a modified amine compound (eg, a salt of carboxylic acid and ammine, an adduct of epoxy compound and ammine) as an essential component, and is active. Agents (eg, amine hydrochlorides, water-soluble carboxylic acids, amines) may be used in combination. The cream solder of Patent Document 3 contains an amine salt of polyoxyethylene diglycolic acid as an essential component as a flux, and activators (eg, ammine hydrochloride, water-soluble carboxylic acid, its amine salt) and thixotropic agents (eg, , Polyethylene dalcol, hydroxycellulose) I am trying. The cream solder of Patent Document 4 contains an ester compound of sodium sulfoisophthalic acid and dallicol as an essential component as a flux, and an activator (eg, amine hydrochloride, water-soluble carboxylic acid, amine salt thereof). And thixotropic agents (eg, polyethylene dalcol, hydroxycellulose) can be used in combination.

The liquid flux of Patent Document 2 is based on water-soluble base materials (eg, polyethylene glycol, mannitol, sorbitol) and activators (organic acids such as taenoic acid, malic acid, malonic acid, lactic acid; ammine hydrochloride) and surface activity. Agent (eg, nonionic surfactant, ionic surfactant, hydroxycellulose, sodium alginate, gum arabic).

[0005] However, the flux in Patent Document 1 and the flux in the cream solders in Patent Document 3 and Patent Document 4 are both chemically synthesized amine-based compounds and iow-based compounds that are thermally decomposed during reflow. There is a problem of generating poisonous gases and odors, and a problem that if the flux residue is washed with water after soldering, it becomes wastewater and flows into sewage treatment plants, rivers, and harbors, which may contaminate the natural environment!

The flux in Patent Literature 1 and the flux in cream solders in Patent Literature 3 and Patent Literature 4 are intended for solders with V as the main component, and the liquid flux in Patent Literature 2 is suitable for any solder. It is not mentioned that it is suitable. However, when they are applied to lead-free solders and lead-free solders, there is a problem that the adhesion force during reflow is insufficient.

[0006] On the other hand, Patent Document 5 proposes an aqueous flats containing ascorbic acid and a surfactant in water. Since ascorbic acid is the main component, it can be affirmed that it is highly safe for the human body and considers the environment, but since surfactant is an essential component, washing the flux residue with water after soldering results in sewage There is a problem that it may flow into the treatment plant, river J11, and harbor, and may contaminate the natural environment. The force does not mention what kind of solder is suitable.

[0007] Patent Document 1: Japanese Patent Laid-Open No. 5-69188

Patent Document 2: JP-A-9-192882

Patent Document 3: Japanese Patent Laid-Open No. 5-69188

Patent Document 4: Japanese Patent Laid-Open No. 5-69189

Patent Document 5: Japanese Unexamined Patent Application Publication No. 2005-74484 Disclosure of the invention

Problems to be solved by the invention

[0008] Therefore, the present inventors have hardly generated toxic gases and odors when soldering with a lead-free solder, and have excellent adhesion during reflow, excellent flushability of the flux residue, and the drainage is treated as sewage. As a result of diligent research to develop soot flux and cream solder that can be quickly decomposed by microorganisms even if it flows into a treatment plant, river j11, or harbor and pollutes the natural environment, the present invention has been achieved.

The objects of the present invention are as follows: (1) Little toxic gas and odor are generated when soldering with lead-free solder, excellent fixability during reflow, excellent flushability of flux residue, and drainage of sewage Flux that decomposes quickly by microorganisms even if it flows into a treatment plant, river j11, or harbor, and does not pollute the natural environment. (2) Little toxic gas or odor is generated when soldering, and excellent adhesion during reflow Excellent solderability of flux residue, and even if the wastewater flows into sewage treatment plants, rivers, and harbors, it is quickly decomposed by microorganisms and does not pollute the natural environment and does not cause lead damage, and (3) Solder The object is to provide food containers and electronic parts that have excellent adhesive strength and are free from lead damage.

Means for solving the problem

The above object is achieved by the following soldering flux, cream solder, soldering method, food container and electronic component.

[1] (A) water and (B) (bl) water-soluble and biodegradable, reducing organic compounds or phenolic antioxidants consisting of carbon, hydrogen and oxygen atoms, or (b2) water-soluble It is characterized by comprising an alkali metal salt of a reducible organic acid consisting of carbon, hydrogen and oxygen atoms, and (C) a water-soluble and biodegradable thixotropic agent. Soldering flux.

[2] Component (bl) is ascorbic acid, sorbic acid, erythorbic acid, citrate, darconic acid, reducing sugar or water-soluble phenolic antioxidant, and component (b2) is sodium ascorbate, sodium sorbate or The soldering flux according to [1], wherein the flux is sodium erythorbate, and the component (C) is a thickening polysaccharide.

[3] Component (A) Component (B) is 0.5 to 500 parts by weight with respect to 100 parts by weight, and Component (C) is 0 2 to 20 parts by weight Soldering flux according to [1] or [2]

[4] A cream solder comprising (D) lead-free solder particles and the soldering flux according to [1] or [2].

[5] A cream solder comprising (D) 100 parts by weight of lead-free solder particles and 3 to 30 parts by weight of the soldering flux according to [3].

[6] Soldering a metal member, wherein the cream solder according to [4] or [5] is located between metal members to be soldered, and the lead-free solder particles are reflowed by heating. Method.

[7] A food container or an electronic component having a metal member soldered using the cream solder according to [4] or [5].

The invention's effect

[0010] The soldering flux of the present invention generates almost no toxic gas or odor when soldering with a lead-free solder, has excellent adhesion during reflow, and has excellent water-washing ability for flux residue. However, even if it flows into sewage treatment plants, rivers, and harbors, it is quickly decomposed by microorganisms and does not pollute the natural environment.

The cream solder of the present invention generates almost no toxic gas or odor when soldering, has excellent adhesion during reflow, has excellent flushability of flux residue, and its wastewater is discharged into sewage treatment plants, rivers, and harbors. Even if it flows in, it will be quickly decomposed by microorganisms and will not pollute the natural environment. The soldering method of the present invention generates almost no toxic gas or odor during soldering, has excellent adhesion during reflow, and has excellent flushability of flux residue, and its wastewater is discharged into sewage treatment plants and rivers. Even if it flows into the harbor, it will be quickly degraded by microorganisms and will not pollute the natural environment. The food container and electronic component of the present invention have excellent soldering strength and no lead damage.

Brief Description of Drawings

[0011] Fig. 1 is a plan view of a specimen A for adhesion strength measurement in an example. Chip capacitor Terminal electrode 3 and substrate land (pad) part 4 are soldered to mount chip capacitor 2 on glass fiber reinforced epoxy resin substrate 1. After fixing, the side surface of the chip capacitor 2 is pressed in the direction of the arrow, and the adhesion strength of the soldered portion between the chip capacitor 2 and the glass fiber reinforced epoxy resin substrate 1 is measured.

FIG. 2 is a cross-sectional view taken along the line in FIG.

Explanation of symbols

[0012] A Test specimen for measuring adhesive strength

1 Glass fiber reinforced epoxy resin substrate

2 Chip capacitor

3 Terminal electrode of chip capacitor

4 PCB land (pad) part

5 Lead-free solder

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] The soldering flux of the present invention comprises (A) water and (B) (bl) a water-soluble and biodegradable reducible organic compound or a phenol-based compound comprising carbon atoms, hydrogen atoms and oxygen nuclear power. An antioxidant or (b2) a water-soluble and biodegradable alkali metal salt of a reducing organic acid consisting of carbon, hydrogen and oxygen atoms, and (C) a water-soluble and biodegradable thixotropic agent. It is characterized by the following.

[0014] (A) Water is (B) (bl) Water-soluble and biodegradable, reducible organic compounds or phenolic antioxidants consisting of carbon, hydrogen and oxygen atoms, or (b2) water-soluble It is a liquid by dissolving an alkali metal salt of a reducing organic acid consisting of carbon atoms, hydrogen atoms and oxygen atoms and (C) a water-soluble and biodegradable thixotropic agent. Is a component for.

Pure water is preferred for water, and its electrical conductivity is preferably 100 μSZcm or less, more preferably 10 μS / cm or less, and even more preferably 3 SZcm or less. The method for producing pure water may be a normal method, and examples include an ion exchange method, a reverse osmosis method, and a distillation method. Well water, mineral water, and valley water can be used if they are clean and have a small amount of minerals.

[0015] Among the components (B) and (bl), a water-soluble and biodegradable reducible organic compound comprising carbon, hydrogen and oxygen atoms, and (b2) water-soluble and biodegradable Alkali metal salts of reducing organic acids such as carbon atoms, hydrogen atoms and oxygen nuclear power When soldering, the oxides on the surface layer of the lead-free solder are reduced to non-oxides, and the metal parts used for soldering are reduced to oxides on the surface layer of metal parts. Acts to return. Among the components (B) and (bl), phenolic antioxidants, which are water-soluble and biodegradable and contain carbon atoms, hydrogen atoms, and oxygen nuclear power, are used for the surface layer of lead-free solder and soldering during reflow. The metal member is effective in preventing the surface layer of the metal part from being oxidized. It improves the soldering strength and strength due to the powerful action.

[0016] Among the components (B) and (bl), ascorbic acid, particularly L-ascorbic acid, and its water-solubility are water-soluble and readily biodegradable, reducing organic compounds such as carbon atoms, hydrogen atoms, and oxygen nuclear power. Examples include derivatives (for example, ascorbic acid 2-darcoside), sorbic acid and its water-soluble derivatives, isoascorbic acid (erythorbic acid) and its water-soluble derivatives, and reducing sugars. Reducing sugars include monosaccharides, disaccharides and oligosaccharides, monosaccharides such as glucose, maltose, ratatoses, fructose, ratatoses and isomaltose, reducing disaccharides such as sucrose, cellobiose, xylobiose and mannobiose and reduction. Examples are sex oligosaccharides. Ascorbic acid, especially L-ascorbic acid and its water-soluble derivatives, have (HO) C = C (OH) and have an excellent reducing ability because they are easily oxidized to dehydro form. Sorbic acid and its water-soluble derivatives have a conjugated double bond and an excellent reducing ability. Reducing sugar has a CHO group (aldehyde group) and has an excellent reducing ability. These substances are also reducing in soldering flux and cream solder.

[0017] Aliphatic rubonic acids such as citrate, lactic acid, darconic acid, malic acid, malonic acid, succinic acid, adipic acid are (HO) C = C (OH) —, CHO group, conjugated double bond Since it does not have any, the reducing ability is smaller than the above, but by using it together with the component (C), the fixing strength at the time of soldering is improved. Of these, citrate and darconic acid are highly preferred because of their high water solubility. Component (B) (bl) is a food additive and has no carboxyl group! /, Ascorbic acid, especially L-ascorbic acid. The powerful component (B) (bl) is washed with water after soldering, and even if it flows into a sewage treatment plant, river j11, or harbor, it is decomposed into a harmless substance by microorganisms that break down into speed and force. Ingredients (B) (bl) are natural substances originally derived from plants, microorganisms or animals (however, adipic acid, sorbic acid and its water-soluble derivatives) Excluding) Excellent safety for human livestock. Sorbic acid is a food preservative and has excellent safety for humans.

[0018] Among the components (B) and (bl), flavonoids such as catechin, rutin, and isoquercitrin are water-soluble and biodegradable phenolic antioxidants that are also carbon atoms, hydrogen atoms, and oxygen nuclear power. Glycosides; gallic acid, hydroquinone, catechol are exemplified. Such components (B) and (bl) are washed with water after soldering, and even if they flow into sewage treatment plants, rivers, and harbors, they are quickly decomposed by microorganisms into harmless substances. Such component (B) (b 1) is originally a natural substance derived from a plant, microorganism or animal (however, excluding hydroquinone and catechol) and is excellent in safety for human livestock.

[0019] (B) (b2) Alkali metal salts of reducible organic acids which are water-soluble and biodegradable and comprise carbon, hydrogen and oxygen atoms are sodium ascorbate, in particular sodium L-ascorbate. , Sodium isoscorbate (sodium erythorbate) and sodium sorbate. Powerful components (B) and (b2) are decomposed quickly by microorganisms into harmless substances even if the residue is washed with water after soldering and flows into sewage treatment plants, rivers, and harbors.

Here, biodegradability in the present invention corresponds to item 5 of the same paragraph based on the provisions of Article 4, Paragraph 1 of the Law on the Examination of Chemical Substances and Regulations on Manufacturing, etc. (so-called white substances) It means that it is judged. Two or more of the above components (B) (bl) and (B) (b2) may be used in combination.

[0020] (C) A water-soluble and biodegradable thixotropic agent increases the viscosity of the soldering flux, and (D) when mixed with lead-free solder particles, the mixture is creamy or pasty. And has a thixotropic effect. The thixotropic agent prevents dripping of cream solder and is necessary for good printability.

Representative examples of component (C) are thickening polysaccharides such as alginic acid, sodium alginate, carrageenan, agar, xanthan gum, guar gum, locust bean gum, tragacanth gum, gum arabic, tamarind seed gum, dielan gum, psyllium seed gum. Examples include gelatin, which is a protein derived from animal collagen, such as natural gums derived from seaweed, seeds, crusts, microorganisms, etc., and plant-derived starches such as pectin. Can. Any one or two or more of these may be used in combination as long as the object of the present invention is achieved. Component (C) is water-soluble, and its residue is washed with water after soldering, and even if it flows into a sewage treatment plant, river j11, or harbor, it is quickly decomposed by microorganisms into a harmless substance. Powerful component (C) is a natural substance originally derived from plants, microorganisms or animals, and has excellent safety for humans.

[0021] The blending ratio of each component in the soldering flux of the present invention is such that the component (B) is 0.5 to 500 parts by weight with respect to 100 parts by weight of the component (A), and the component (C) is 0.5. It is preferably 2 to 20 parts by weight. More preferably, the component (B) is 3 to 300 parts by weight and the component (C) is 1 to LO parts by weight with respect to 100 parts by weight of the component (A). The viscosity of the soldering flux of the present invention is preferably 1 to 100, 00 OmPa's at 25 ° C in order to make cream solder into a cream or paste 50 ~: LO, OOOmPa ' s is more preferable.

[0022] The soldering flux of the present invention can be obtained by, for example, adding the component (B) and the component (C) to the component (A) and stirring at room temperature or while heating, or by mixing the component (A) And component (C) are stirred at room temperature or while heating, and then component (B) is added and stirred, or component (A) and component (B) are stirred, and It can be easily produced by adding (C) and stirring at room temperature or while heating.

[0023] The cream solder of the present invention is (D) lead-free solder particles and the soldering flack, that is, (A) water, (B) (bl) water-soluble and biodegradable. Reducing organic compounds or phenolic antioxidants consisting of carbon, hydrogen and oxygen atoms or (b2) water-soluble and biodegradable reducing organic acids consisting of carbon, hydrogen and oxygen atoms The soldering flux comprises an alkali metal salt and (C) a water-soluble and biodegradable thixotropic agent.

Component (D) Lead-free solder particles are characterized by not containing Pb, Sn-In, Sn-Bi, In-Ag, In-Bi, Sn-Zn, Sn-Ag, Sn-Cu, Sn-Sb, Sn-Au, Sn-Bi-Ag-Cu, Sn-Ge, Sn-Bi-Cu, Sn-Cu-Sb-Ag, Sn-Ag-Zn , Sn-Cu-Ag, Sn-Bi-Sb, Sn-Bi-Sb-Zn, Sn-Bi-Cu-Zn, Sn-Ag-Sb, Sn-Ag-Sb-Zn Sn-Ag-Cu-Zn system and Sn-Zn-Bi system are exemplified. [0024] More specifically, 48Sn / 52In, 43Sn / 57Bi, 97In / 3Ag, 58Sn / 42In, 95In / 5Bi, 60Sn / 40Bi, 91Sn / 9Zn, 96.5Sn / 3.5Ag, 99.3Sn / 0 7Cu, 95 Sn / 5Sb, 20Sn / 80Au, 90Sn / 10Ag, Sn90 / Bi7.5 / Ag2 / CuO.5, 97S n / 3Cu, 99SnZlGe, 92Sn / 7.5Bi / 0. 5Cu, 97Sn / 2Cu / 0 8Sb / 0. 2 Ag, 95. 5Sn / 3. 5Ag / lZn, 95. 5Sn / 4Cu / 0. 5Ag, 52Sn / 45Bi / 3Sb, 51Sn / 45Bi / 3Sb / lZn, 85Sn / 10Bi / 5Sb, 84Sn / 10Bi / 5Sb / lZn, 8 8. 2Sn / 10Bi / 0. 8Cu / lZn, 89Sn / 4Ag / 7Sb, 88Sn / 4Ag / 7Sb / lZn, 98Sn / lAg / lSb, 97Sn / lAg / lSb / lZn,, 91. 2Sn / 2Ag / 0.8Cu / 6Zn, 89Sn / 8Zn / 3Bi, 86Sn / 8Zn / 6Bi, 89.lSn / 2Ag / 0.9Cu / 8Zn force are exemplified. It may be a mixture of two or more lead-free solder particles with different metal element compositions.

[0025] Among the above lead-free solder particles, Sn-Bi, Sn-Bi-Ag, Sn-Ag, Sn-Ag-Cu, and Sn-Zn lead-free solder particles are preferred. When the cream solder is prepared, the reflow temperature is lowered to the same level as the Sn—Pb solder particles. Therefore, it becomes lead-free solder particles that can extend the life of mounted components, and it can cope with diversification of mounted components.

[0026] The average particle size of the lead-free solder particles used in the present invention is not particularly limited, and is usually 0.1 to 100 m, preferably 1 to 40 m. The particle size measurement of lead-free solder particles is a laser diffraction / scattering particle size distribution measurement method.

The lead-free solder particles used in the present invention define the upper limit of the solder particle size by sieving, lead-free solder particles having a particle size below the sieve opening, and the particle force weight distribution is 90% or more, preferably 95% or more. It is good. In addition, the oxygen atom content of the lead-free solder particles used in the present invention is preferably as low as possible, preferably 500 ppm or less, more preferably 300 ppm or less. As a result, the storage stability of cream solder improves the reflow characteristics. In order to reduce the oxygen atom content in the lead-free solder particles, the atomization process for producing the lead-free solder particles is performed in an atmosphere in which the lead-free solder particles are difficult to oxidize, or the produced lead-free solder particles are not easily oxidized. It is effective to handle in the environment. Specifically, it is preferable to perform the above process in nitrogen gas or inert gas. [0027] The cream solder of the present invention is required to have a blending ratio such that (D) the mixture of the lead-free solder particles and the soldering flux is in the form of cream or paste. It is preferable that the force is 100 parts by weight of the particles and 3 to 30 parts by weight of the soldering flux. More preferably, the soldering flux force is 15 parts by weight per 100 parts by weight of lead-free solder particles.

[0028] When (D) lead-free solder particles and (A) water are mixed, sometimes cream solder tends to exhibit dilatancy, and in this case, the container force having a thin discharge port such as a tube or syringe is also discharged. However, the water-soluble and biodegradable thixotropic agent (C) used in the present invention has the effect of improving the discharge ability of cream solder with these container forces and facilitating the discharge. . In addition, in order to improve the discharge performance of containers with small discharge ports such as syringes and cartridges by dilatancy, aliphatic hydrocarbons such as volatile isoparaffins and monovalent linear alcohols with 3 to 10 carbon atoms May be added.

[0029] The method for producing the cream solder of the present invention is not particularly limited. (D) If the lead-free solder particles and the soldering flux are mixed to form a paste or cream. In order to adjust the viscosity and thixotropy, either component (A), component (B), component (C), or component (D) may be added or mixed afterwards. Good.

[0030] The cream solder of the present invention thus prepared is not particularly limited as long as it has a viscosity that can be used for soldering, but at 25 ° C, 1 to: LOOO Pa's It is preferable that When applying cream solder with a syringe, cartridge, tube, etc., l-300 Pa's is more preferable. When printing with a screen, stencil, mask, etc., 10 to 25 ° C: LOOOPa's is preferable, and 20 to 200 Pa · s is more preferable! /.

[0031] The cream solder of the present invention includes various metal powders, alloy powders, non-metal powders, powders such as composites, heat stabilizers, and colorants as long as the object of the present invention is not hindered. Further, it may contain a preservative, a water retention agent and the like. It should be noted that the compounds and rosin fluxes described in the above-mentioned patent documents that do not meet the object of the present invention are not included.

[0032] The cream solder of the present invention is applied to a location where soldering of metal members is required, and heated to reflow the lead-free solder particles, thereby soldering the metal members together. You can. Examples of application methods include coating, pouring, and dropping. The heating conditions may be any temperature and time for melting the lead-free solder particles. After melting, when cooled, the lead-free solder solidifies and firmly bonds the metal members.

After soldering with the cream solder of the present invention, the flux residue can be easily and quickly washed and washed by washing with water. Because it can be washed with water

There is no problem of VOC generation as in the case of washing with organic solvents such as alcohol.

When the cream solder of the present invention is heated to reflow the lead-free solder particles, a metal member such as a gold-plated substrate, a silver substrate, a silver plating metal substrate, a copper substrate, an aluminum substrate, a nickel plating substrate, a tin plating Metal substrates such as metal substrates; aluminum plates, nickel plating plates

, Metal plates such as tinplate, etc .; because it has excellent adhesion to metal parts such as electrodes on electrically insulating substrates, it can be used for electronic parts, electronic devices, electrical parts, and electrical devices that have metallic substrates and metal parts. It is useful for soldering food containers, food processing equipment, food production equipment and the like. As such soldering, soldering of chip parts such as capacitors and resistors and circuit boards; soldering of semiconductor chips such as diodes, memories, and CPUs to lead frames or circuit boards; and CPU chips with high heat generation Examples include soldering with a cooling plate, metal cans for canning, and metal cans for food storage.

Example

[0034] The following examples and comparative examples explain the present invention in more detail.

The characteristics of the soldering flux and cream solder in the examples and comparative examples were measured by the following methods.

[0035] [Viscosity]

Using a rotary viscometer TV-20 manufactured by Toki Sangyo Co., Ltd., the temperature was measured at 25 ° C. and the rotational speed of the rotor was 4 rpm.

[0036] [Fixing strength]

150 mm wide x 40 mm long glass fiber reinforced epoxy resin board 1 on two 0.8 mm x 1.2 mm land (pad) parts 4 (silver finish), spaced 1 mm apart, 150 Apply cream solder using an m-thick metal mask (application area: 0.6 mm x 1. Omm), and use a chip mounter to attach the terminal electrode 3 of the 2012 chip capacitor to the land (pad). ) After mounting on part 4 (silver finish), soldering is performed by reflowing at 200 ° C for 30 minutes or 250 ° C for 30 seconds in a forced circulation oven. A specimen was prepared. The side surface of chip capacitor 2, which is a test specimen for measuring the bond strength obtained by force, is pressed at a pressing speed of 23 mmZ using a bond strength tester, and the bond strength (with the load when the soldered part breaks and breaks) Unit: kgf). The number of times of the bond strength test was 5, and the average value of 5 times was defined as the bond strength.

[0037] [Flux residue after washing with water]

Using an ultrasonic cleaner (USM type, manufactured by SNUD Co., Ltd.), the same specimen as the specimen for fixing strength measurement was ultrasonically cleaned in pure water at 25 ° C for 2 minutes, and the specimen was pulled up. The adhesion state of the flux residue in the soldered portion was visually observed.

[0038] [Example 1]

A commercially available distilled water and L-ascorbic acid (manufactured by Wako Pure Chemical Industries, Ltd., reagent grade) were added to a container equipped with a stirrer and stirred to prepare a 15% by weight aqueous solution of L-ascorbic acid. To 100 parts by weight of this aqueous solution, 3 parts by weight of alginic acid (trade name “Agar” manufactured by Kyoritsu Foods Co., Ltd.) is added and dissolved under thickening by heating to dissolve the thickening polysaccharide. (Viscosity 150 mPa · s) was prepared.

In a mixer, lead-free solder particles consisting of 41% by weight of tin, 58% by weight of bismuth and 1% by weight of silver, with an average particle size of 35 μm and a melting point of 136 ° C (PF141 particles manufactured by Nihon Nonda Co., Ltd.) ) By mixing 100 parts by weight and 9 parts by weight of the above soldering flux, a tail solder was prepared.

This cream solder had a viscosity of 25 Pa's, was thixotropic, had good applicability without sagging or flowing when applied with a metal mask, and had a sticking strength of 4. Okgf. After washing with water, no residue of flux was observed.

[0039] [Comparative Example 1]

In Example 1, instead of a 15% by weight aqueous solution of L-ascorbic acid, an aqueous solution obtained by mixing 100 parts by weight of commercially available distilled water with 3 parts by weight of alginic acid (trade name “Agar” manufactured by Kyoritsu Foods Co., Ltd.) A soldering flux (viscosity 140 mPa · s) was prepared using the same, and cream solder was prepared under the same conditions. This cream solder has a viscosity of 22 Pa's It was thixotropic, and there was no sagging or flow in coating with a metal mask, and it had good coating properties. Even after reflowing, lead-free solder particles did not melt and soldering was not possible.

[0040] [Comparative Example 2]

In Example 1, instead of the soldering flux, a 15% by weight aqueous solution of L-ascorbic acid was used as a polyether type nonionic surfactant polyoxyethylene alkyl ether (trade name Leox CC 50, manufactured by Lion Corporation). the a 0.01 weight ^_0/0 addition soldering flux (viscosity lOmPa 's below) were prepared and others were prepared tally Muhanda under the same conditions. This cream solder had a viscosity of 0.80 Pa's, and was poor in applicability due to dripping and flow when applied with a metal mask.

[Example 2]

In a container equipped with a stirrer, commercially available distilled water and sorbic acid (made by Wako Pure Chemical Industries, Ltd., reagent grade) were added and stirred to prepare a 50% by weight aqueous solution of sorbic acid. To 100 parts by weight of this aqueous solution, 3 parts by weight of alginic acid (trade name “Agar”, manufactured by Kyoritsu Foods Co., Ltd.) is added, and the mixture is stirred under heating to dissolve the thickening polysaccharide. A flux (viscosity 330 mPa-s) was prepared.

Lead-free solder particles consisting of 96% tin, 3% silver and 1% copper in the mixer, with an average particle size of 35 μm and a melting point of 220 ° C (PF305 particles manufactured by Nihon Nonda Co., Ltd.) Cream solder was prepared by mixing 100 parts by weight and 11 parts by weight of the above soldering flux.

This cream solder had a viscosity of 32 Pa's, was thixotropic, had good applicability without sagging and flow when applied with a metal mask, and had a sticking strength of 4. Okgf. After washing with water, no residue of flux was observed.

[0042] [Comparative Example 3]

In Example 2, instead of the 50% by weight aqueous solution of sorbic acid, 100 parts by weight of commercially available distilled water was mixed with 3 parts by weight of alginic acid (trade name “Agar” manufactured by Kyoritsu Foods Co., Ltd.). The soldering flux (viscosity: 140 mPa · s) was prepared using the same, and the cream solder was prepared under the same conditions. This cream solder has a viscosity of 23 Pa's. Although it was a xotropic, there was no sagging or flow when applied with a metal mask, but the lead-free solder particles did not melt even when reflowed, and the soldering was not possible.

[0043] [Example 3]

The agitator container with a commercially available distilled water and D (+) glucose (Wako Pure Chemical Industries, Ltd., special grade reagent) Inputs and stirred to prepare a 50 weight ^_0/0 aqueous solution of D (+) glucose. To 100 parts by weight of this aqueous solution, 3 parts by weight of alginic acid (trade name “Agar”, manufactured by Kyoritsu Foods Co., Ltd.) is added and stirred under heating to dissolve the thickening polysaccharide. A flux (viscosity 420 mPa · s) was prepared.

In a mixer, lead-free solder particles consisting of 41% by weight of tin, 58% by weight of bismuth and 1% by weight of silver, with an average particle size of 35 μm and a melting point of 136 ° C (PF141 particles manufactured by Nihon Nonda Co., Ltd.) ) By mixing 100 parts by weight and 12 parts by weight of the above soldering flux, a time solder was prepared. This cream solder had a viscosity of 28 Pa's, was thixotropic, had good applicability without sagging or flowing when applied with a metal mask, and had a sticking strength of 1.8 kgf. After washing with water, no residue of flux was observed.

[0044] [Comparative Example 4]

In Example 3, instead of a 50% by weight aqueous solution of D (+) glucose, 100 parts by weight of commercially available distilled water was mixed with 3 parts by weight of alginic acid (trade name “Agar” manufactured by Kyoritsu Foods Co., Ltd.). A soldering flux (viscosity 140 mPa · s) was prepared using the aqueous solution, and cream solder was prepared under the same conditions. This cream solder has a viscosity of 22 Pa's, is thixotropic, and has good applicability without sagging or flowing when applied with a metal mask, but lead-free solder particles melt even when reflowed. Cannot be attached without o

[0045] [Example 4]

The agitator container with a commercially available distilled water and L- Asukorubin acid (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was prepared 15 weight ^_0/0 aqueous solution was poured stirring to L- Asukorubin acid. To 100 parts by weight of this aqueous solution, 3 parts by weight of citrus-derived thickening polysaccharide Bectin (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred under heating to dissolve pectin. Thus, a soldering flux (viscosity 850 mPa's) was prepared. In a mixer, lead-free solder particles consisting of 41% by weight of tin, 58% by weight of bismuth and 1% by weight of silver, with an average particle size of 35 μm and a melting point of 136 ° C (PF141 particles manufactured by Nihon Nonda Co., Ltd.) ) By mixing 100 parts by weight and 12 parts by weight of this soldering flux, a tail solder was prepared. This cream solder had a viscosity of 85 Pa's, was thixotropic, had good applicability without sagging or flowing when applied with a metal mask, and had a fixing strength of 3.7 kgf. After washing with water, no residue of flux was observed.

[0046] [Comparative Example 5]

In Example 4, instead of using a 15% by weight aqueous solution of L-ascorbic acid, an aqueous solution obtained by mixing 100 parts by weight of commercially available distilled water with 3 parts by weight of pectin was used to make a soldering flats (viscosity 770 mPa's The cream solder was prepared under the same conditions. This cream solder has a viscosity of 75 Pa's, is thixotropic, and has good applicability without sagging or flowing when applied with a metal mask, but lead-free solder particles melt even when reflowed. I couldn't put on the power without any effort.

[0047] [Example 5]

Commercially distilled water and (+) catechin (manufactured by Tokyo Chemical Industry Co., Ltd., reagent) were added to a vessel equipped with a stirrer and stirred to prepare a 5% by weight aqueous solution of (+) catechin. To 100 parts by weight of this aqueous solution, 3 parts by weight of alginic acid (trade name “Agar”, manufactured by Kyoritsu Foods Co., Ltd.) is added and stirred under heating to dissolve the thickening polysaccharide. (Viscosity 200 mPa-s) was prepared.

In a mixer, lead-free solder particles consisting of 41% by weight of tin, 58% by weight of bismuth and 1% by weight of silver, with an average particle size of 35 μm and a melting point of 136 ° C (PF141 particles manufactured by Nihon Nonda Co., Ltd.) ) A solder paste was prepared by mixing 100 parts and 10 parts by weight of the above soldering flux. This cream solder had a viscosity of 33 Pa's, was thixotropic, had good applicability without sagging or flowing when applied with a metal mask, and had a fixing strength of 2.9 kgf. After washing with water, no residue of flux was observed.

[0048] [Comparative Example 6]

In Example 5, instead of 10 parts by weight of a 5% by weight aqueous solution of (+) catechin, a rosin flux solution having a medium activity of JIS Z 3 284 classification II (solid content 65% by weight, chlorine Cream solder was prepared using 10 parts by weight of 0.06% by weight and a viscosity of 6,000 mPa's). This cream solder had a viscosity of 150 Pa's, was thixotropic, had good applicability without sagging or flowing when applied with a metal mask, and had a sticking strength of 4. Okgf. When the residue after washing with water was visually observed, a residue was observed in the soldered portion of the glass fiber epoxy resin substrate. This amount of residue was about half of the amount of residue before washing with water. Industrial applicability

The soldering flux of the present invention is useful for the production of cream solder mainly containing lead-free solder particles.

The cream solder of the present invention is useful for soldering in which flux residue is washed away after soldering.

The soldering method of the present invention is useful for removing a flux residue by washing with water after soldering a metal member.

The food container of the present invention is useful for storing and transporting food, and the electronic component of the present invention is useful for being incorporated in electronic equipment.

Claims

The scope of the claims

[1] (A) Water and (B) (bl) Water-soluble and biodegradable reducible organic compounds or phenolic antioxidants consisting of carbon, hydrogen and oxygen atoms or (b2) Water-soluble It is characterized by comprising an alkali metal salt of a reducing organic acid consisting of carbon, hydrogen and oxygen atoms and (C) a water-soluble and biodegradable thixotropic agent. Soldering flux.

[2] Component (bl) is ascorbic acid, sorbic acid, erythorbic acid, citrate, darconic acid, reducing sugar, water-soluble phenolic antioxidant or hydroquinone, and component (b2) is sodium ascorbate, sorbine The soldering flux according to claim 1, wherein the soldering flux is sodium sulfate or sodium erythorbate, and the component (C) is a thickening polysaccharide.

[3] The component (B) is 0.5 to 500 parts by weight and the component (C) is 0.2 to 20 parts by weight with respect to 100 parts by weight of the component (A). Or a soldering flutter according to claim 2.

[4] A cream solder comprising (D) lead-free solder particles and the soldering flux according to claim 1 or 2.

[5] A cream solder comprising (D) 100 parts by weight of lead-free solder particles and 3 to 30 parts by weight of the soldering flux according to claim 3.

[6] Soldering of a metal member, wherein the cream solder according to claim 4 or 5 is located between the metal members to be soldered, and lead-free solder particles are reflowed by heating. Method.

[7] A food container or electronic component having a metal member soldered using the cream solder according to claim 4 or claim 5.