JP4447798B2 - Solder paste composition and reflow soldering method - Google Patents

Description

【００１７】
表１の結果から、酸化防止剤を併用したソルダーペーストである実施例１及び実施例２のものは、酸化防止剤を使用しない比較例１のものに比べて、プリヒート温度が１５０℃の場合にもはんだ付状態は良好であるが、プリヒート温度が２００℃の場合には特に優れ、その他の性能も劣るものはないといえる。
【００１８】
【発明の効果】
本発明によれば、分子量が少なくとも５００であるヒンダードフェノール系化合物からなる酸化防止剤を併用したので、高温のリフロー時においても無鉛系はんだ粉末及びフラックス膜の熱劣化を防止することができ、はんだ付性の特性が低下せず、例えば２００℃、１２０のプリヒート、２４０℃、３０秒の本加熱を行ってもよいように、リフロー時のヒートパターンの変更により高温に弱い電子部品の熱損傷を避けることができ、これにより回路の信頼性の高い実装基板を得ることができるソルダペースト組成物及びリフローはんだ付方法を提供することができる。[0001]
[Industrial application fields]
In particular, the present invention relates to a solder paste composition suitable for use of a solder alloy powder not containing lead and zinc, and a reflow soldering method using the same.
[0002]
[Prior art]
In recent years, surface mounting technology has rapidly developed along with the multi-functionalization, miniaturization, and miniaturization of wiring boards for electronic devices. When surface mounting electronic components, reflow soldering methods that use solder paste are mostly used. ing. The solder powder used for the solder paste is mostly Sn-Pb-based.
However, if the electronic equipment is disposed of after it has been used, etc., it is disassembled and part of it is recovered, but the mounting board on which the electronic components are mounted is crushed and landfilled without being recovered. The current situation is that some are left in nature.
Since electronic components are soldered on the mounting board dumped in nature, if this solder contains lead, it will be eluted as a soluble lead compound due to acid rain, etc., and pollutes nature. In addition, contaminated water and animal and plant foods may be ingested by humans through groundwater, which is becoming a serious problem because of its high toxicity.
Accordingly, lead-free solder materials have been developed, and so-called lead-free solder alloy powders such as Sn—Ag alloys and Sn—Ag—Cu alloys have been used.
[0003]
[Problems to be solved by the invention]
However, since the above lead-free solder alloy powder has a high melting point of about 200 to 220 ° C., the reflow soldering method using the solder paste containing the solder powder has a peak temperature during heating of 230 to 240 ° C. In the case of a lead-based Sn—Pb alloy, the melting point of its eutectic composition (63Sn / 37Pb) is as low as 183 ° C., and the reflow soldering method using the solder paste containing the solder powder Then, the peak temperature of the heating may be about 230 ° C., and heat-sensitive electronic components can be soldered without damage, but there is a problem that functional deterioration due to the heat damage occurs.
In order to improve this problem, the solder paste containing the above lead-free solder alloy powder is used to set the peak temperature during reflow soldering to a low temperature of 230 to 240 ° C., and instead the solder alloy during reflow Attempts have been made to mitigate thermal damage to electronic components by changing the so-called heat pattern, in which heating is performed at a higher temperature during preheating so that the powder can be efficiently melted. Since the amount of heat during heating increases, the solder alloy powder and flux of the solder paste film applied to the soldered part of the printed wiring board are excessively heated, which tends to cause thermal deterioration due to oxidation, and the flux film during reflow And insoluble matter in the solder powder, reducing the solderability characteristics such as reducing the soldering strength. To cause another new problem that has come to be known.
[0004]
A first object of the present invention is to provide a solder paste composition and a reflow soldering method capable of preventing thermal deterioration of lead-free solder powder and flux film even at high temperature reflow.
A second object of the present invention is to provide a solder paste composition and a reflow soldering method in which the solderability characteristics are not deteriorated even when a lead-free solder powder is used.
The third object of the present invention is to provide a solder paste composition and a reflow soldering method capable of avoiding thermal damage of electronic components that are vulnerable to high temperatures by changing the heat pattern during reflow when lead-free solder powder is used. There is to do.
A fourth object of the present invention is to provide a solder paste composition and a reflow soldering method capable of obtaining a mounting substrate with high circuit reliability even when a lead-free solder powder is used.
[0005]
[Means for Solving the Problems]
As a result of diligent research to solve the above problems, the present inventor, as for the solder paste using a hindered phenol-based compound in combination with a lead-free solder powder, during reflow of the lead-free solder powder and the solder paste film It has been found that deterioration is prevented, and has led to the present invention.
Accordingly, the present invention provides (1), non-lead-based solder powder, rosin resin, in solder paste composition containing an active agent and a solvent, an antioxidant that the molecular weight is at least 500 der Ruhi down hindered phenolic compound A solder paste composition containing an agent is provided.
In the present invention, (2) the hindered phenol compound having a molecular weight of at least 500 is triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1 , 6-hexanediol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5- Di-t-butyl-4-hydroxy-hydrocinnamamide) and the like (1) solder paste composition, (3), soldering of printed circuit board The hindered phenolic compound having a molecular weight of at least 500 is triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] or 1,6 -Hexanediol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] using the solder paste composition of (1) above , preheating at 200 ° C. for 120 seconds, 240 The present invention provides a reflow soldering method for performing reflow soldering that may be performed at a temperature of ° C.
In addition, “ (1), a solder paste composition containing a lead-free solder powder, a rosin resin, an activator and a solvent, and a solder paste composition containing an antioxidant composed of a hindered phenol compound. In addition, the present invention relates to (2) the solder paste composition of (1) above, wherein the molecular weight of the hindered phenol-based compound is at least 500, (3), an electron with respect to the soldered portion of the printed circuit board. A reflow soldering method for reflow soldering a part using the solder paste composition according to claim 1 or 2 is provided.
The lead-free solder powder may be a solder alloy powder not containing lead and zinc. It can also be said.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the lead-free solder powder is a solder powder having no lead component, for example, a solder powder not containing lead and zinc is preferable. For this, Sn-Ag, Sn-Ag-Cu, Sn-Ag -Bi, Sn-Bi, Sn-Ag-Cu-Bi, Sn-Sb, Sn-Cu, etc. are exemplified, and there is no particular limitation as long as it is a solder alloy not containing lead and zinc. Sn-Zn alloy solder powder may also be used.
Lead-free solder powder is used in the solder paste at 85 to 92% (flux: 8 to 15%), and the solder powder having a spherical shape with a particle size of 300 to 700 mesh has recently become narrow in the pitch of the soldered land. This is preferable for reflow soldering to printed circuit boards.
[0007]
Examples of the rosin resin used in the present invention include rosin and derivatives thereof such as modified rosin, and these can be used in combination. Specifically, for example, gum rosin, wood rosin, polymerized rosin, phenol-modified rosin and derivatives thereof. Is mentioned. The content of the rosin resin can be 30 to 70% in the so-called flux, which is another component excluding the solder powder of the solder paste composition. If it is less than this, oxidation of the copper foil surface of the soldering land will be prevented and the solder will be easily wetted, so-called solderability will be reduced, and solder balls will be likely to be formed. Become more.
[0008]
Examples of the activator include organic amine hydrohalides and organic acids. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine hydrochloride, triethanolamine bromide. Examples include hydroacid salt, monoethanolamine hydrobromide, adipic acid, sebacic acid, etc. These suppress corrosion by residue and do not impair insulation resistance. From the standpoint of preventing the occurrence of the above, 0.1 to 3% in the flux is preferable.
[0009]
In addition, a thixotropic agent may be used. For example, hydrogenated castor oil, fatty acid amides, and oxy fatty acids are fluxed so that the solder paste can be adjusted to a viscosity suitable for its printability. It is preferable to contain 3 to 15%.
Examples of the solvent include those used in ordinary solder paste, such as hexyl carbitol (boiling point: 260 ° C.), butyl carbitol (boiling point: 230 ° C.), etc. It is preferable to contain 50%.
[0010]
In the present invention, an antioxidant comprising a hindered phenol compound (which may contain a small amount of other components) is used. Specifically, for example, it is added to a flux, and this flux is lead-free. It is used in such a manner that it is stirred and mixed with the system solder powder.
Although it does not specifically limit as a hindered phenol type compound, Specifically, a triethyleneglycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1, 6-hexane. Diol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di -T-butylanilino) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphene) ) Propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-t-butyl-4-hydroxybenzyl phosphonate -Diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene and the like.
Of these, those having a molecular weight of 500 or more are particularly preferred because of excellent thermal stability.
[0011]
The antioxidant composed of a hindered phenol compound is preferably 10% or less (at most 10%) in the flux. If the addition amount is larger than this, the solderability may be lowered. The reason why the antioxidant made of a hindered phenol compound exhibits the effect of preventing the solder paste flux film and lead-free solder powder from deteriorating has not been clearly clarified. In this case, hydrogen is given to the radicals of the decomposition products generated by the action of heat or light on the polymer hydrocarbons, and the activation of the radicals is lost and stabilized, so that the decomposition products are generated in a chain. It can be considered that the progress of the deterioration reaction in which insoluble matter is partially generated by the reaction is prevented. In the case of lead-free solder powder can also be considered the oxygen in the atmosphere Attempting to react with the metal shall be stabilized.
[0012]
【Example】
Hereinafter, examples will be described, but the present invention is not limited to the following examples.
[0013]
Example 1
A solder paste having the following composition was prepared.
Hydrogenated rosin (rosin resin) 55.0g
Adipic acid (active agent) 2.0 g
Hydrogenated castor oil (thixotropic agent) 6.0g
Triethylene glycol-bis [3- (3-t-butyl-5-
Methyl-4-hydroxyphenyl) propionate] (antioxidant) 5.0 g
Hexyl carbitol (solvent) 33.0g
(Flux 100g)
Flux 11.0g
Solder powder 89.0g
(Sn / Ag / Cu = 96.5 / 3 / 0.5)
(Solder paste 100g)
A solder paste was obtained by stirring and mixing the flux and the solder powder. When this solder paste was measured with a Malcolm viscometer, it was 230 Pa · s (measurement temperature 25 ° C.). In addition, using this solder paste, (1) printability test (test for inspecting whether or not fading or blurring is visually observed on the printing surface by screen printing using a metal mask having a thickness of 0.15 mm), ▲ 2) Adhesion test (examines the peelability of the metal mask after printing, JIS Z 3284 test), (3) Sagging test during heating (examines the protrusion of the coating film from a predetermined position during heating) In JIS Z 3284) and (4) Insulation test (which measures the resistance value of the flux film separated from the solder, test according to JIS Z 3284). Test (In the reflow soldering apparatus, the main heating is performed in each of the case where the preheating temperature is 150 ° C. and 120 seconds and the case where the preheating temperature is 200 ° C. and 120 seconds. The soldering state after 30 seconds is a five-step method in which unmelted solder is not seen in the solidified solder after melting, 1 is often seen, and 3 or more is practical. Table 1 shows the results of the test to be evaluated.
[0014]
Example 2
The solder paste was used in the same manner as in Example 1 except that the antioxidant was used instead of 1,6-hexanediol-bis- [3- (3,5-t-butyl-4-hydroxyphenyl) propionate]. Table 1 shows the results of the preparation and the viscosity and other tests conducted in the same manner as in Example 1.
[0015]
Comparative Example 1
A solder paste was prepared in the same manner as in Example 1 except that the antioxidant was not used, and the viscosity and other results tested in the same manner as in Example 1 are shown in Table 1.
[0016]
[Table 1]

[0017]
From the results in Table 1, the solder paste of Example 1 and Example 2 which is a solder paste combined with an antioxidant is compared with that of Comparative Example 1 which does not use an antioxidant when the preheat temperature is 150 ° C. Although the soldering state is good, it can be said that it is particularly excellent when the preheating temperature is 200 ° C., and that other performance is not inferior.
[0018]
【The invention's effect】
According to the present invention, since an antioxidant composed of a hindered phenol compound having a molecular weight of at least 500 is used in combination, it is possible to prevent thermal deterioration of the lead-free solder powder and the flux film even during high temperature reflow, without lowering the characteristics of the solderability, for example 200 ° C., 120 Preheating, 240 ° C., as may be carried out the heating of 30 seconds, a weak heat of the electronic component to a high temperature by changing the heat pattern during reflow It is possible to provide a solder paste composition and a reflow soldering method capable of avoiding damage and thereby obtaining a highly reliable circuit board.

Claims (3)

Non-lead-based solder powder, rosin resin, in solder paste composition containing an active agent and a solvent, the molecular weight is solder paste composition containing an antioxidant comprising at least 500 der Ruhi down hindered phenolic compound. A hindered phenol compound having a molecular weight of at least 500 is triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis- [3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2 -Thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy- The solder paste composition according to claim 1, such as hydrocinnamamide) . An electronic component is mounted on a soldered portion of a printed circuit board, and a hindered phenol compound having a molecular weight of at least 500 is triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl). Propionate] or 1,6-hexanediol-bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] at 200 ° C. using the solder paste composition according to claim 1 A reflow soldering method in which reflow soldering may be performed, in which preheating at 120 seconds and main heating at 240 ° C. may be performed .