JP2014036985A - Solder composition and printed wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solder composition capable of sufficiently suppressing sagging in preheating while keeping printability.SOLUTION: A solder composition contains a rosin-based resin, amide-based condensation fine particles, a solvent, a surfactant, an amine-based compound, and solder powder. The amide-based condensation fine particles are fine particles which contain a low-molecular-weight amide compound obtained by condensing an aliphatic carboxylic acid that contains a hydroxy aliphatic monocarboxylic acid and has 2 to 22 carbon atoms, and any one of diamine and dimer diamine of 2 to 16 carbon atoms; and a high-molecular-weight amide compound obtained by condensing the carboxylic acid of the same kind as the aliphatic carboxylic acid, the diamine of the same kind as any one of the diamine and the dimer diamine, and a carboxyl group-containing polymer having a weight average molecular weight of 2,000 to 100,000. The content of the amide-based condensation fine particles is 1.1 pts.mass or more and 2.7 pts.mass or less with respect to 100 pts.mass of the rosin-based resin.

Description

  The present invention relates to a solder composition (so-called solder paste) for mounting a component on a printed wiring board of an electronic device, and a printed wiring board on which an electronic component is mounted using the solder composition.

  The solder paste is a mixture obtained by kneading solder powder, rosin resin, activator, solvent and the like into a paste. This solder paste is required to have printability and solderability, as well as a property (sagging property) that suppresses sagging during preheating in the reflow process (the shape of the coating film of the solder paste collapses during preheating). However, if the viscosity or thixotropy of the solder paste is increased in order to improve the sag of the solder paste, the printability of the solder paste tends to be lowered. Thus, printability and sag are in a trade-off relationship, and it is difficult to achieve both.

  Therefore, for example, a solder paste containing a predetermined block polymer has been proposed (Patent Document 1). However, since the preheating temperature tends to increase with the recent lead-free solder powder, sagging tends to occur. Moreover, since the space | interval of terminals becomes narrow with the miniaturization of an electronic component, the further suppression of sagging is calculated | required. Therefore, further improvement of sagging property at the time of preheating is required.

JP 2002-336993 A

  An object of this invention is to provide the solder composition which can fully suppress dripping at the time of preheating, and a printed wiring board using this solder composition, maintaining printability.

  As a result of intensive studies to achieve the above object, the present inventors have found the following knowledge. That is, there are many components (so-called thixotropic agents) that can adjust the thixotropy of the solder composition, and among such many thixotropic agents, a specific low molecular weight amide compound and a specific high molecular weight amide compound are contained. Surprisingly, when the amide-based condensate fine particles to be used are used, it has been surprisingly found that droop during preheating can be sufficiently suppressed while maintaining printability, and the present invention has been completed.

  That is, the solder composition of the present invention contains a rosin resin, amide-based condensate fine particles, a solvent, an activator, an amine-based compound, and a solder powder. A C2-C22 aliphatic carboxylic acid containing an aliphatic monocarboxylic acid, a low-molecular weight amide compound obtained by condensing any diamine of C2-C16 diamine and dimer diamine, and the same carboxylic acid And a high molecular weight amide compound obtained by condensing the same kind of the diamine and a carboxyl group-containing polymer having a weight average molecular weight of 2000 to 100000, and the content of the amide-based condensate fine particles is 100 masses of the rosin-based resin. 1.1 parts by mass or more and 2.7 parts by mass or less with respect to parts.

  The printed wiring board of the present invention is characterized in that an electronic component is mounted on a printed wiring board using the solder composition.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the solder composition which can fully suppress dripping at the time of preheating, and the printed wiring board using this solder composition, maintaining printability.

The solder composition of this invention contains the solder powder demonstrated below and the flux demonstrated below.
The solder powder used in the present invention is preferably a lead-free solder powder, but may be a leaded solder powder. As the solder alloy in the solder powder, an alloy containing tin or bismuth as a main component is preferable. In addition, examples of the second element of the alloy include silver, copper, zinc, bismuth, tin, and lead. Furthermore, you may add another element (after 3rd element) to this alloy as needed. Examples of other elements include copper, silver, nickel, cobalt, iron, antimony, titanium, phosphorus, and germanium.
The content of the solder powder is preferably 85% by mass or more and 92% by mass or less with respect to 100% by mass of the solder composition. When the content of the solder powder is less than 85% by mass (when the content of the flux exceeds 15% by mass), when the obtained solder composition is used, it tends to be difficult to form a sufficient solder joint. On the other hand, when the content of the solder powder exceeds 92% by mass (when the content of the flux is less than 8% by mass), the flux as the binder is insufficient and it is difficult to mix the flux and the solder powder. Tend to be.

  The average particle size of the solder powder is preferably 1 μm or more and 40 μm or less, more preferably 10 μm or more and 35 μm or less, and particularly preferably 15 μm or more and 25 μm or less. If the average particle diameter is within the above range, it is possible to cope with recent printed circuit boards in which the pitch of the solder lands is narrow. The average particle size can be measured with a dynamic light scattering type particle size measuring device.

The flux used in the present invention contains a rosin resin, amide condensate fine particles, a solvent, an activator, and an amine compound.
Examples of the rosin resin used in the present invention include rosin and rosin derivatives. Examples of the rosin derivative include modified rosin, polymerized rosin, and hydrogenated rosin. Among these rosin-based resins, hydrogenated rosin is preferable from the viewpoint of activity. These rosin resins may be used alone or in combination of two or more.

The amide-based condensate fine particles used in the present invention are obtained by condensing an aliphatic carboxylic acid having 2 to 22 carbon atoms including a hydroxyaliphatic monocarboxylic acid, and any one of diamines having 2 to 16 carbon atoms and dimer diamine. And a high molecular weight amide compound obtained by condensing the same kind of the carboxylic acid, the same kind of the diamine, and a carboxyl group-containing polymer having a weight average molecular weight of 2000 to 100,000.
The amide-based condensate fine particles preferably contain 99 to 50: 1 to 50 of the low molecular weight amide compound: the high molecular weight amide compound in a mass ratio.
In the amide-based condensate fine particles, the aliphatic carboxylic acid preferably contains an aliphatic dicarboxylic acid having 2 to 12 carbon atoms, or the same kind of aliphatic dicarboxylic acid and dimer acid.
In the amide-based condensate fine particles, the hydroxy aliphatic monocarboxylic acid is preferably a hydrogenated castor oil hydrolyzate.
In the amide-based condensate fine particles, the carboxyl group-containing polymer is copolymerized with a copolymerization monomer or polycondensed with a polycondensation monomer in the presence of a compound obtained by oxidizing polyalkylene and a carboxyl group-containing compound monomer. A polyalkylene oxide selected from the above compounds is preferred.

The amide-based condensate fine particles are preferably used in the form of a dispersion. Moreover, the dispersion liquid of amide-type condensate fine particles can be produced as follows, for example.
First, 1 molar equivalent of aliphatic carboxylic acid and 0.5 molar equivalent of aliphatic diamine are heated to 160-230 ° C. without solvent at normal pressure or under vacuum for 2-10 hours. Allow condensation reaction. Then, the aliphatic carboxylic acid and the aliphatic diamine are condensed, the acid value and the amine value are 20 or less, a light yellow to light brown solid having a melting point of 100 to 160 ° C. and melted by heat. It becomes a low molecular weight amide compound. On the other hand, at least 1% by mass, preferably 1 to 50% by mass, more preferably 1 to 10% by mass of a carboxyl group-containing polymer is added, and the dehydration condensation reaction is further performed for 1 to 5 hours. Then, a part of the low molecular weight amide compound becomes a high molecular weight amide compound by a dehydration condensation reaction between the unreacted amino group and the carboxyl group of the carboxyl group-containing polymer. As a result, a wax containing a high molecular weight amide compound and a low molecular weight amide compound, having an acid value of 30 or less, preferably 5 to 20, and an amine value of 20 or less, preferably 7 or less is obtained. Next, the wax is made into fine particles pulverized to a micron order, for example, 20 μm or less, preferably 10 μm or less by a pulverizer. The fine particles and the solvent are blended, and the fine particles are dispersed in the solvent by a mechanical dispersion method using a disper or a dispersion method using a wet disperser using a medium such as glass beads. Under heating, for example, while heating to 40 to 100 ° C., preferably 50 to 90 ° C., depending on the solvent, the solvent is impregnated over an appropriate time depending on the heating conditions and the solvent. Then, the fine particles swell and a dispersion of amide-based condensate fine particles is obtained.
In addition, although the dehydration condensation of the aliphatic carboxylic acid and the aliphatic diamine was performed, and the dehydration condensation was further performed by adding the carboxyl group-containing polymer, the aliphatic carboxylic acid, the aliphatic diamine, and the carboxyl group were shown. The containing polymer may be mixed and dehydrated and condensed at the same time.

  The content of the amide-based condensate fine particles needs to be 1.1% by mass or more and 2.7% by mass or less with respect to 100 parts by mass of the rosin-based resin. When the content is less than the lower limit, the printability is insufficient and sagging easily occurs. On the other hand, when the content exceeds the upper limit, the printability becomes insufficient. Further, from the viewpoint of further improving sagging during preheating while maintaining printability, the content of the amide-based condensate fine particles is 1.4% by mass or more and 2% by mass with respect to 100 parts by mass of the rosin-based resin. It is preferably 0.5% by mass or less, more preferably 1.7% by mass or more and 2.3% by mass or less, and particularly preferably 1.9% by mass or more and 2.2% by mass or less.

In the flux used in the present invention, the amide condensate fine particles and other thixotropic agents may be used in combination.
Examples of such thixotropic agents include olefin waxes, fatty acid amides, substituted urea waxes, polymer compounds, and inorganic particles.
Examples of the olefin wax include castor wax (hardened castor oil = hydrogenated castor oil), beeswax, and carnauba wax.
Examples of fatty acid amides include stearic acid amide, hydroxystearic acid bisamide, m-xylylene bisstearic acid amide, N, N′-distearylisophthalic acid amide, N, N′-distearyl sebacic acid amide, N, N′— Distearyl adipic acid amide, butylene bishydroxystearic acid amide, hexamethylene bishydroxystearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, ethylene bisbehenic acid amide, ethylene bishydroxystearic acid amide, Ethylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis capric acid amide, ethylene bis caprylic acid amide, methylene bis hydroxy stearic acid amide, methylene bis lauric acid amide, methylene Such Susutearin acid amide.
Examples of substituted urea waxes include N-butyl-N′-stearyl urea, N-phenyl-N′-stearyl urea, N-stearyl-N′-stearyl urea, xylylene bisstearyl urea, toluylene bisstearyl urea, hexamethylene Examples thereof include bisstearyl urea, diphenylmethane bisstearyl urea, and diphenylmethane bislauryl urea.
Examples of the polymer compound include 1,2-hydroxystearic acid triglyceride, polyethylene glycol, polyethylene oxide, methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose.
Examples of the inorganic particles include silica particles and kaolin particles.
These thixotropic agents may be used alone or in combination of two or more.

  The thixotropic agent content is preferably 1% by mass or more and 10% by mass or less with respect to 100 parts by mass of the rosin resin. If the content is less than the lower limit, thixotropy cannot be obtained and the sagging tends to occur. On the other hand, if the content exceeds the upper limit, the thixotropy tends to be too high and the coating tends to be poor.

As the solvent used in the present invention, a known solvent can be appropriately used. As the solvent, a water-soluble solvent having a boiling point of 170 ° C. or higher is preferably used.
Examples of the solvent include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, hexyl diglycol, 1,5-pentanediol, methyl carbitol, butyl carbitol, 2-ethylhexyl diglycol, octanediol, and phenyl. Glycol, diethylene glycol monohexyl ether. These solvents may be used alone or in combination of two or more.

  The content of the solvent is preferably 20 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the rosin resin. If content of the said solvent is in the said range, the viscosity of the solder composition obtained can be suitably adjusted to an appropriate range.

Examples of the activator used in the present invention include organic acids and organic halogen compounds. These activators may be used individually by 1 type, and may mix and use 2 or more types.
As said organic acid, other organic acids other than monocarboxylic acid, dicarboxylic acid, etc. are mentioned, for example. These organic acids may be used alone or in combination of two or more.
Monocarboxylic acids include formic acid, acetic acid, propionic acid, petric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid Arachidic acid, behenic acid, lignoceric acid, glycolic acid and the like.
Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, diglycolic acid and the like.
Examples of other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid.

  Examples of the organic halogen compound include dibromobutenediol, dibromosuccinic acid, 5-bromobenzoic acid, 5-bromonicotinic acid, and 5-bromophthalic acid. These organic halogen compounds may be used alone or in combination of two or more.

  The content of the activator is preferably 2 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rosin resin. If the content is less than the lower limit, solder balls tend to be easily formed. On the other hand, if the content exceeds the upper limit, the insulating properties of the flux tend to decrease.

Examples of amine compounds used in the present invention include imidazole compounds and triazole compounds. These amine compounds may be used individually by 1 type, and 2 or more types may be mixed and used for them.
Examples of the imidazole compound include benzimidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 2-undecylimidazole.
Examples of the triazole compound include benzotriazole, 1H-benzotriazole-1-methanol, and 1-methyl-1H-benzotriazole.

  The content of the amine compound is preferably 0.1 parts by mass or more and 5 parts by mass or less, and 0.3 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the rosin resin. More preferred. If the content is less than the above lower limit, solder tends to be unmelted and unwetting to the substrate land. On the other hand, if the content exceeds the upper limit, the storage stability of the resulting solder composition tends to decrease. is there.

  The flux used in the present invention contains additives such as a thixotropic agent, an antifoaming agent, an antioxidant, a rust inhibitor, a surfactant, and a thermosetting agent in addition to the above components as necessary. Also good. The content of these additives is preferably 20 parts by mass or less with respect to 100 parts by mass of the rosin resin.

  Next, the printed wiring board of the present invention will be described. The printed wiring board of the present invention is characterized in that an electronic component is mounted on a printed wiring board using the solder composition described above. Therefore, sagging during preheating can be sufficiently suppressed even with the printed wiring board of the present invention.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples. In addition, the material used in the Example and the comparative example is shown below.
Rosin resin: hydrogenated rosin, solvent manufactured by Arakawa Chemical Industries, Ltd .: hexyl diglycol (DEH), dispersion of amide-based condensate fine particles manufactured by Nippon Emulsifier Co., Ltd .: See Production Example 1 below, amide-based condensate fine particles in dispersion The concentration of 20% by mass
Thixo Agent A: Fatty Acid Amide (Fatty Acid Amide), Trade Name “Sripax LA”, Nippon Kasei Co., Ltd. Thixo Agent B: Fatty Acid Amide (Fatty Acid Amide), Product Name “Sripac H”, Nippon Kasei Co., Ltd. Thixo Agent C: 12- Hydroxystearic acid triglyceride, Nippon Kasei Co., Ltd. activator A: Dibromobutenediol, Air Brown Co., Ltd. activator B: Adipic acid, Tokyo Chemical Industry Co., Ltd. activator C: Malonic acid, Toshin Kasei Co., Ltd. amine compound: Benzimidazole, lead-free solder powder manufactured by Tokyo Chemical Industry Co., Ltd .: average particle size is 17 μm, solder composition is 96.5Sn / 3Ag / 0.5Cu

[Production Example 1]
600.0 parts by mass of 12-hydroxystearic acid derived from hydrogenated castor oil fatty acid was added to a reaction apparatus equipped with a stirrer, a thermometer, and a water separator, and the mixture was heated to 80 to 100 ° C. and melted. Then, 116.0 parts by mass of hexamethylenediamine, which is a diamine, was added, and a condensation reaction was carried out while dehydrating at 170 ° C. in a nitrogen atmosphere for 5 to 8 hours, whereby an acid value of 4.2 and an amine value of 9. 4 low molecular weight diamide compounds were obtained. Furthermore, 68.0 parts by mass of a carboxyl group-containing polymer which is a propylene / maleic anhydride copolymer having a weight average molecular weight of 10,000 and an acid value of 80 mgKOH / g is added, and a condensation reaction is performed while dehydrating at 170 ° C. for 1 to 2 hours. Then, a part of the low molecular weight diamide compound was reacted with an unreacted amino group to be amidated to produce a high molecular weight diamide compound. As a result, a pale yellow mixture of a low molecular weight diamide compound and a high molecular weight diamide compound (acid number 6.0, amine number 4.2) was obtained as a wax-like product. The obtained product was pulverized to obtain amide-based condensate fine particles atomized to an average particle size of 7 μm.
Next, 120 parts by mass of a mineral terpene, 40 parts by mass of benzyl alcohol and 40 parts by mass of the obtained amide-based condensate fine particles were added to a sealed container and sufficiently dispersed at 10 to 20 ° C. to obtain a suspension. . Thereafter, when the sealed container containing the suspension was heated by a known method, the fine particles swelled, and a dispersion of amide-based condensate fine particles was obtained. The concentration of the amide-based condensate fine particles in this dispersion is 20% by mass.

[Example 1]
100 parts by mass of rosin resin, 51 parts by mass of solvent, 6.3 parts by mass of dispersion of amide-based condensate fine particles, 1.8 parts by mass of activator A, 4.5 parts by mass of activator B, 1.2 parts by mass of activator C, And 0.4 mass part of amine-type compounds were thrown into the container, and it mixed using the raking machine, and obtained the flux.
Thereafter, 11% by mass of the obtained flux and 89% by mass of the lead-free solder powder (100% by mass in total) were put into a container and mixed in a kneader for 2 hours to prepare a solder composition.

[Examples 2 to 9]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1.
[Comparative Examples 1-5]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 2.

<Evaluation of solder composition>
Evaluation of the solder composition (viscosity, viscosity index, properties, sagging property during heating, printability) was performed by the following method. The obtained results are shown in Tables 1 and 2.
(1) Viscosity and Viscosity Index The solder composition is allowed to stand at room temperature (25 ° C.) for 2 to 3 hours. Open the lid of the solder composition container, and use a spatula that is gently stirred for 1-2 minutes so as to avoid air contamination. Thereafter, the sample is set in a spiral viscometer (Malcom Corp., PCU-II type), and the rotor is rotated for 6 minutes at a rotation speed of 10 rpm and a temperature of 25 ° C. Then, once the rotation is stopped and the temperature is adjusted, the rotation number is adjusted to 10 rpm, and the viscosity value after 3 minutes is read.
Further, in the same manner as described above, the viscosity value when the rotation speed is adjusted to 30 rpm (30 rpm viscosity) and the viscosity value when the rotation speed is adjusted to 3 rpm (3 rpm viscosity) are read. And the following formula:
(Viscosity index) = log [(3 rpm viscosity) / (30 rpm viscosity)]
Based on the above, the viscosity index is calculated.
(2) Properties Visually confirm that the solder composition is glossy. Then, the solder composition is stirred with a spatula at the center and side of the container to check the smoothness.
○: There is no problem in gloss and smoothness.
X: There is a problem in at least one of gloss and smoothness.

(3) Sag at heating A clean ceramic substrate (manufactured by Sanyu Industrial: 25 mm × 50 mm × 0.8 mm) is prepared. It has a pattern hole of 3.0 mm x 1.5 mm and has a pattern hole in which it is arranged in steps of 0.1 mm from 0.1 mm to 1.2 mm, with a thickness of 0.2 mm (error is within 0.001 mm) Using a metal mask, the solder composition is printed on this ceramic substrate to obtain a test plate. Two test plates are prepared. Then, the test plate is placed in a furnace heated to 170 ° C. and heated for 1 minute. Each of the two test plates after heating is observed, and the minimum interval at which the printed solder composition is not integrated is measured among the pattern holes.
(4) Printability Using a printing machine MK-878SV (manufactured by Minami Co., Ltd.), a 0.1 mm thick metal mask and a metal squeegee, a printing speed of 50 mm / s, an SP-TDC substrate (a substrate having a dot pattern of 100 points, The solder composition is printed on a dot diameter (0.2 mmφ to 0.5 mmφ). After printing on 20 SP-TDC substrates, it is left at 25 ° C. and 50% for 1 hour. After leaving, printing is resumed, and the solder composition is printed on 10 SP-TDC substrates. Thereafter, the transfer rate (average value of the volume rate for 100 dots) is measured with a three-dimensional shape analyzer.
○: The average transfer rate after being left (the average value of the transfer rate of 10 substrates) is the same as that before being left within 3rd.
(Triangle | delta): It is the 4th or 5th sheet that the average transfer rate after leaving becomes the same value as before leaving.
X: The average transfer rate after being left is the same as that before being left after the sixth sheet.

As is apparent from the results shown in Tables 1 and 2, when the solder composition of the present invention was used (Examples 1 to 9), both the printability and the sagging property during heating were excellent. Therefore, according to the solder composition of the present invention, it was confirmed that sagging during preheating can be sufficiently suppressed while maintaining printability.
On the other hand, when a solder composition containing no amide-based condensate fine particles was used (Comparative Examples 1 and 2), the sagging property during heating was insufficient. In addition, when the content of the amide-based condensate fine particles in the flux was not appropriate (Comparative Examples 3 to 5), it was impossible to achieve both printability and sagging property during heating.

  The solder composition of the present invention can be suitably used as a technique for mounting a component on a printed wiring board of an electronic device.

Claims (2)

Containing rosin resin, amide condensate fine particles, solvent, activator, amine compound, and solder powder;
The amide-based condensate fine particles have a low molecular weight obtained by condensing an aliphatic carboxylic acid having 2 to 22 carbon atoms including a hydroxy aliphatic monocarboxylic acid, and a diamine having 2 to 16 carbon atoms and dimer diamine. Fine particles containing an amide compound and a high molecular weight amide compound obtained by condensing the same kind of the carboxylic acid, the same kind of the diamine, and a carboxyl group-containing polymer having a weight average molecular weight of 2000 to 100,000.
A content of the amide-based condensate fine particles is 1.1 parts by mass or more and 2.7 parts by mass or less with respect to 100 parts by mass of the rosin resin.   An electronic component is mounted on a printed wiring board using the solder composition according to claim 1.