JP6204007B2 - Flux composition, solder paste composition, and printed wiring board - Google Patents

Description

  The present invention relates to a flux composition, a solder paste composition using the same, and a printed wiring board having a flux residue formed using the same.

  With the downsizing and multi-functionalization of electronic devices, the use of a solder paste composition in which a flux composition and a solder alloy are mixed is increasing when electronic components are mounted on a printed wiring board. Conventionally, as this solder alloy, an alloy containing lead has been used. In recent years, however, lead-free solder alloys have been widely used due to environmental problems. However, since a lead-free solder alloy has a higher melting temperature than lead-containing solder, indium may be contained in the solder alloy for the purpose of improving mechanical properties while lowering the melting temperature. In particular, in an environment where the temperature difference is large (for example, −40 ° C. to 125 ° C.) as in the vicinity of the engine of a car, a solder paste composition using a solder alloy with improved mechanical properties is desired. It has been.

  However, a solder paste composition using a solder alloy containing indium easily generates a metal salt because indium reacts with rosin and activator contained in the flux composition. The produced metal salt increases the viscosity of the solder paste composition, and such a solder paste composition has a problem that solder balls are easily generated. When the solder ball is generated, it causes an open defect such as an unfused phenomenon between the package electrode mounted on the printed wiring board and the solder paste, or a short circuit. Therefore, it is required to use a solder paste composition that can suppress the generation of solder balls, particularly in an in-vehicle substrate that requires high reliability.

  Here, flux that blends polyethylene glycol for the purpose of preventing the reaction between indium and rosin (refer to Patent Document 1), and suppresses the reaction between the solder powder containing indium and the flux, and gives viscosity stability over time and printing. For this purpose, a solder paste containing an amine halogen salt and a dicarboxylic acid in a flux component (see Patent Document 2) is disclosed.

  However, although the flux disclosed in Patent Document 1 suppresses the reaction between indium and rosin, the effect of suppressing oxidation during reflow of indium is not sufficient. Therefore, in order to suppress generation | occurrence | production of a solder ball, the mixing | blending of the further active agent is needed.

  In addition, since the solder paste disclosed in Patent Document 2 uses a dicarboxylic acid having a small carbon number, it has excellent activity, but in the presence of moisture, it is likely to dissolve and become ions, which may cause migration.

JP-A-5-228690 JP 2012-71337 A

  SUMMARY OF THE INVENTION The present invention solves the above problems, and can suppress the generation of solder balls even when a solder alloy containing indium is used. It is an object of the present invention to provide a paste composition and a printed wiring board using these.

  In order to achieve the above object, the flux composition, solder paste composition, and printed wiring board of the present invention are characterized by having the following constitution.

(1) The flux composition of the present invention is a flux composition containing (A) a rosin compound, (B) an activator, and (C) a solvent, and the blending amount of the rosin compound (A) is a flux. 50% by weight or less based on the total amount of the composition, and 5 to 50% by weight of hydrogenated rosin having a maleic anhydride skeleton in the structure as the rosin compound (A) based on the total amount of the flux composition, The blending amount of B) is 20% by weight or less with respect to the total amount of the flux composition, and the activator (B) contains 2 to 12% by weight of an organic acid having 5 to 20 carbon atoms based on the total amount of the flux composition. It is characterized by that.

  (2) In the configuration of (1) above, the flux composition of the present invention uses an organic acid having 5 to 20 carbon atoms and an organic acid having 3 or less carbon atoms as the activator (B). It is characterized by that. In this case, the blending amount of the organic acid having 3 or less carbon atoms is preferably 1% by weight or less based on the total amount of the flux composition.

  (3) In the configuration of (1) or (2) above, the organic acid having 5 to 20 carbon atoms has two carboxyl groups, and the carboxyl groups are bonded to both ends of the carbon chain, respectively. It is characterized by being an acid.

  (4) In the constitution of (1), (2) or (3) above, the blending amount of the hydrogenated rosin containing the maleic anhydride skeleton blended as the rosin compound (A) is the total amount of the flux composition. It is characterized by being 20 to 40% by weight based on the weight.

  (5) Moreover, the solder paste composition of this invention is characterized by including the flux composition of said (1), (2), (3) or (4), and a solder alloy.

  (6) In the configuration of (5) above, the solder alloy includes indium.

  (7) Furthermore, the printed wiring board of the present invention is characterized by having a flux residue formed by using the solder paste composition of (5) or (6).

Hydrogenated rosin containing a maleic anhydride skeleton in the structure as the rosin compound (A) is blended in an amount of 5 to 50% by weight based on the total amount of the flux composition, and the organic acid having 5 to 20 carbon atoms as the activator (B). By mixing 2 to 12% by weight with respect to the total amount of the flux composition, the solder paste composition containing the flux composition of the present invention and the solder alloy can suppress the generation of solder balls.
In particular, when hydrogenated rosin containing a maleic anhydride skeleton in the structure as the rosin compound (A) is blended in an amount of 20 to 40% by weight based on the total amount of the flux composition, a higher solder ball generation suppressing effect can be achieved.
Furthermore, when the organic acid having 5 to 20 carbon atoms and the organic acid having 3 or less carbon atoms are used in combination as the activator (B), the effect of suppressing the generation of solder balls can be further improved.
Even when the solder alloy contains indium that easily oxidizes and easily generates solder balls, the solder paste composition using the flux composition of the present invention can suppress the generation of solder balls.
Thus, the solder paste composition using the flux composition of the present invention has high reliability, and can be suitably used for a vehicle-mounted substrate.

FIG. 1 is a diagram showing a reflow temperature profile used when evaluating the solder ball generation rate of a solder paste composition according to an embodiment of the present invention. FIG. 2 is a diagram showing a part of a comb-shaped electrode substrate pattern used in evaluating the solder ball generation rate of the solder paste composition according to the embodiment.

  Hereinafter, an embodiment of the flux composition and the solder paste composition of the present invention will be described in detail.

(A) Rosin compound As the rosin compound (A) used in the present invention, a hydrogenated rosin containing a maleic anhydride skeleton in its structure is preferably used. The hydrogenated rosin containing the maleic anhydride skeleton in its structure may be used alone or in combination with rosins such as natural rosin, polymerized rosin, hydrogenated rosin, maleated rosin, disproportionated rosin, and derivatives thereof. it can.

Such a hydrogenated rosin containing a maleic anhydride skeleton in its structure can be produced, for example, by a method in which a maleic anhydride component and a purified rosin are subjected to Diels-Alder reaction and hydrogenated.
Examples of the purified rosin used for producing a hydrogenated rosin having a maleic anhydride skeleton in its structure include those obtained by purifying gum rosin, wood rosin, tall oil rosin and the like using a steam distillation method or the like. The reaction temperature in the Diels-Alder reaction between the maleic anhydride component and the purified rosin is, for example, 120 to 300 ° C, preferably 180 to 240 ° C, and the reaction time is preferably 1 to 9 hours.
Furthermore, a known method can be used as a method for hydrogenating the Diels-Alder reactant obtained above, and is not particularly limited.

  The blending amount of the rosin compound (A) is preferably 50% by weight or less based on the total amount of the flux composition. And the compounding quantity of the hydrogenated rosin which contains a maleic anhydride skeleton in the structure is 5 to 50 weight% with respect to the flux composition whole quantity. A preferable blending amount of the hydrogenated rosin containing a maleic anhydride skeleton in the structure is 10 to 50% by weight, and a more preferable blending amount is 20 to 40% by weight with respect to the total amount of the flux composition. If the amount of hydrogenated rosin containing a maleic anhydride skeleton in the structure is less than 5% by weight, the effect of suppressing the generation of solder balls is reduced, which is not preferable.

(B) Activator As the activator (B) used in the present invention, an organic acid having 5 to 20 carbon atoms is preferably used. This organic acid having 5 to 20 carbon atoms can be used alone or in combination with other organic acids, amines, or halides thereof. In particular, when an organic acid having 5 to 20 carbon atoms and an organic acid having 3 or less carbon atoms are used in combination, the solder ball generation suppressing effect of the solder paste composition can be improved.
The organic acid having 5 to 20 carbon atoms is preferably an organic acid having two carboxyl groups and bonded to both ends of the carbon chain. Examples of such organic acids include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid, which are linear saturated fatty acids having 5 to 20 carbon atoms. Examples include acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, and eicosanedioic acid. These can be used alone or in combination of two or more.
As the organic acid having 3 or less carbon atoms, for example, oxalic acid and malonic acid are preferably used.
In addition, as the organic acid having 5 to 20 carbon atoms and the organic acid having 3 or less carbon atoms, organic acids having a branched chain structure or a cyclic structure other than the above can be used.

It is preferable that the compounding quantity of an activator (B) is 20 weight% or less with respect to the flux composition whole quantity. Moreover, the more preferable compounding quantity of an activator (B) is 15 weight% or less with respect to the flux composition whole quantity.
And the compounding quantity of a C5-C20 organic acid in it is 2 to 12 weight% with respect to the flux composition whole quantity. Moreover, the preferable compounding quantity of a C5-C20 organic acid is 6-12 weight% with respect to the flux composition whole quantity, and a more preferable compounding quantity is 8-12 weight%. If the blending amount of the organic acid having 5 to 20 carbon atoms is less than 2% by weight, the effect of inhibiting the generation of solder balls is reduced, which is not preferable. On the other hand, when the blending amount of the organic acid having 5 to 20 carbon atoms exceeds 12% by weight, the solder paste composition is thickened and its storage stability is deteriorated.
Moreover, when using together organic acid with 3 or less carbon atoms, it is preferable that the compounding quantity is 1 weight% or less with respect to the flux composition whole quantity. Further, the blending amount is more preferably 0.5% by weight or less based on the total amount of the flux composition.

(C) Solvent The solvent (C) can be blended with the flux composition of the present invention. Examples of such a solvent include isopropyl alcohol, ethanol, acetone, toluene, xylene, ethyl acetate, ethyl cellosolve, butyl cellosolve, glycol ether and the like. These can be used alone or in combination. It is preferable that the compounding quantity of a solvent (C) is 20 to 70 weight% with respect to the flux composition whole quantity.

(D) Antioxidant Antioxidant (D) can be mix | blended with the flux composition of this invention in order to suppress the oxidation of a solder alloy. Examples of such antioxidant (D) include hindered phenolic antioxidants, phenolic antioxidants, bisphenolic antioxidants, and polymer-type antioxidants. Of these, hindered phenol-based oxidizing agents are particularly preferably used, but usable antioxidants are not limited to these. These can be used alone or in combination.
By mix | blending antioxidant (D) with a flux composition, the wettability of a solder alloy can be improved more or generation | occurrence | production of a ball can be suppressed.
Although the compounding quantity of antioxidant (D) is not specifically limited, Generally it is about 0.5 to 5 weight% with respect to the flux composition whole quantity.

(E) Thixotropic agent A thixotropic agent (E) can be mix | blended with the flux composition of this invention in order to adjust a solder paste composition to the viscosity suitable for printing. Examples of such a thixotropic agent (E) include, but are not limited to, hydrogenated castor oil, fatty acid amides, and oxy fatty acids.
The amount of the thixotropic agent (E) is preferably 3 to 15% by weight based on the total amount of the flux composition.

  Furthermore, you may add additives, such as a halogen, a delustering agent, and an antifoamer, to the flux composition of this invention. The amount of such additives is preferably 10% by weight or less based on the total amount of the flux composition. The blending amount is more preferably 5% by weight or less based on the total amount of the flux composition.

Solder alloy Examples of the solder alloy used in the solder paste composition of the present invention include Sn, Ag, Cu, Bi, Zn, In, Ga, Sb, Au, Pd, Ge, Ni, Cr, Al, P, In, and the like. A combination of a plurality of As typical solder alloys, lead-free solder alloys such as Sn-Ag-Cu and Sn-Ag-Cu-In are used.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is explained in full detail, this invention is not limited to these Examples.

<Generation of hydrogenated rosin containing maleic anhydride skeleton>
(A) 700 g of gum rosin purified using a steam distillation method and 154 g of maleic anhydride are charged into a reaction vessel, and this is reacted with stirring under a nitrogen stream under the reaction conditions of a temperature of 220 ° C. and a reaction time of 4 hours. It was. Thereafter, an unreacted product was removed under reduced pressure to obtain an addition reaction product.
(A) 500 g of the addition reaction product obtained in the above (a) and 6.0 g of 5% palladium carbon (water content 50%) were charged into a 1 liter rotary autoclave to remove oxygen in the system, and hydrogen was used. The system was pressurized to 100 MPa and heated up to 220 ° C. Thereafter, a hydrogenation reaction was carried out at a temperature of 220 ° C. for 3 hours to obtain a hydrogenated rosin containing a maleic anhydride skeleton in the structure. In this example, the obtained hydrogenated rosin containing the maleic anhydride skeleton in the structure is further purified under the following conditions.
(C) 400 g of hydrogenated rosin containing maleic anhydride skeleton in the structure and 200 g of xylene were charged in a reaction vessel and heated to dissolve. Thereafter, 150 g of xylene was distilled off from the dissolved product. Next, 150 g of cyclohexane was added to the reaction vessel, and after cooling to room temperature, when the yield of crystals reached about 40 g, the supernatant was moved to another reaction vessel and recrystallized at room temperature. Thereafter, the supernatant was further removed, washed with 20 g of cyclohexane, and the cyclohexane was distilled off.

Reference Example 1 and Examples 2 to 8
Each component described in Table 1 was kneaded to obtain a flux composition. 11 parts by weight of each flux composition and 89 parts by weight of Sn-3Ag-0.5Cu-4Bi-2In solder alloy (particle size: 20 to 36 μm) are mixed, and the solder paste composition according to the present invention and reference examples is mixed. Produced. In addition, the unit of the numerical value of Table 1 is a weight part unless there is particular notice.

Comparative Examples 1-3
Each component described in Table 2 was kneaded to obtain a flux composition. 11 parts by weight of each flux composition and 89 parts by weight of Sn-3Ag-0.5Cu-4Bi-2In solder alloy (particle diameter: 20 to 36 μm) were mixed to prepare a solder paste composition as a comparative example. In addition, the unit of the numerical value of Table 2 is a weight part unless there is particular notice.

※１ エイコサン二酸（炭素数２０）：岡村製油（株）製
※２ ドデカン二酸（炭素数１２）：岡村製油（株）製
※３ 炭素数３４の二量化脂肪酸：Ｕｎｉｏｎ Ｃａｍｐ Ｃｏｒｐｏｒａｔｉｏｎ製
※４ ヒンダートフェノール系酸化防止剤：ＢＡＳＦジャパン（株）製
※５ ヘキサメチレンヒドロキシステアリン酸アマイド：日本化成（株）製

* 1 Eicosanedioic acid (carbon number 20): Okamura Oil Co., Ltd. * 2 Dodecanedioic acid (carbon number 12): Okamura Oil Co., Ltd. * 3 Carbon 34 dimerized fatty acid: Union Camp Corporation * 4 Hindered phenolic antioxidant: BASF Japan KK * 5 Hexamethylene hydroxystearic acid amide: Nippon Kasei KK

For each of the solder paste compositions of Reference Example 1 and Examples 2 to 8 and Comparative Examples 1 to 3, the number of solder balls generated was measured and evaluated under the following conditions. The results are shown in Table 3 and Table 4, respectively.

Solder ball generation rate <Measurement method>
Solder paste compositions of Reference Example 1, Examples 2 to 8, and Comparative Examples 1 to 3, after applying OSP to the comb electrode substrate used in the insulation resistance test specified in JIS standard Z3197 and performing preflux treatment Was printed with a screen printer (product name: SP60P-2, manufactured by Panasonic Corporation) using a metal mask having a film thickness of 100 μm. Within 10 minutes after printing, using a reflow system (product name: TNP40-577PH, manufactured by Tamura Corporation), reflow is performed under the reflow temperature profile conditions and atmospheric conditions shown in FIG. did. About each produced test piece, the melting state of the soldering part was observed at a magnification of 50 using a stereomicroscope (product name: DSZ-44F, manufactured by Carton Optical Co., Ltd.), and the generated solder balls per conductor The average number of was calculated. The term “between one conductor” refers to one frame surrounded by a dotted line shown in FIG.
<Evaluation method>
Evaluation was performed under the following conditions based on the number of solder balls generated between conductors, and the evaluation results passed from ◎ to Δ.
20 or less: ◎
21 or more and 100 or less: ○
101 or more and 200 or less: △
201 or more: ×

As described above, as in Examples 2 to 8, the solder resist composition using the flux composition of the present invention in which a specific amount of hydrogenated rosin containing a maleic anhydride skeleton in the structure and an organic acid having 5 to 12 carbon atoms is blended is Even when an indium-containing solder alloy having the property of being easily oxidized is included, the generation of solder balls can be suppressed. Further, as shown in Example 6 and Example 7, even when a hydrogenated rosin containing a maleic anhydride skeleton in the structure and another rosin are used in combination, a hydrogenated rosin containing a maleic anhydride skeleton in the structure is used alone. It can be seen that the same effect is obtained as when used.

100 Comb electrode substrate 10 Pattern S Conductivity

Claims (3)

A flux composition comprising (A) a rosin compound, (B) an activator, (C) a solvent, and (D) an antioxidant ,
The blending amount of the rosin compound (A) is 50% by weight or less based on the total amount of the flux composition,
5 to 50% by weight of hydrogenated rosin containing a maleic anhydride skeleton in the structure as the rosin compound (A) with respect to the total amount of the flux composition;
The amount of the active agent (B) is 20% by weight or less based on the total amount of the flux composition,
The activator (B) has 2 to 12% by weight of carboxylic acid having 5 to 12 carbon atoms having two carboxyl groups and bonded to both ends of the carbon chain, respectively, based on the total amount of the flux composition. malonic acid viewing containing 1 wt% or less with respect to the flux the total amount of the composition and,
And a flux composition comprising including Mukoto a hindered phenolic antioxidant as the antioxidant (D),
A solder paste composition comprising a solder alloy containing indium.   2. The solder paste composition according to claim 1, comprising 20 to 40% by weight of hydrogenated rosin having a maleic anhydride skeleton in the structure as the rosin compound (A) based on the total amount of the flux composition.   A printed wiring board comprising a flux residue formed using the solder paste composition according to claim 1.

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