JP4502430B2 - Solder wettability improving treatment agent and method for improving solder wettability of tin and tin alloy - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a solder wettability improving treatment agent and a method for improving solder wettability of tin and tin alloy, in particular, in a connection part of an electronic component connected to another component, a substrate, a signal line, etc. by soldering, Used to treat pre-plated tin and tin alloy plated surfaces.
[0002]
[Prior art]
Conventionally, plating containing lead, that is, so-called solder plating, is mainly applied to a soldering portion of an electronic component that places importance on solderability. However, solder plating containing lead has a problem of environmental pollution due to lead contained in the plating, and the current situation is that it is shifted to lead-free plating that does not substantially contain lead. Examples of lead-free plating include tin single plating and tin-based tin alloy plating, that is, alloy plating of tin-copper, tin-silver, tin-bismuth, tin-zinc, tin-indium, and the like. Plating has a problem that solder wettability, particularly solder wettability with time, deteriorates as compared with the case of solder plating containing lead.
[0003]
[Problems to be solved by the invention]
An object of this invention is to provide the solder wettability improvement processing agent of the film which does not contain lead for solder. Another object of the present invention is to provide a method of treating a solder film that does not contain lead using the wettability improving agent.
[0004]
[Means for Solving the Problems]
According to the present invention, when a treatment agent containing diterpenic acid or a derivative thereof and an aliphatic hydrocarbon is overcoated on a solder film that does not contain lead, solder wettability immediately after plating and over time can be improved. It was made based on knowledge.
That is, this invention provides the solder wettability improvement processing agent characterized by containing diterpenic acid or its derivative (s), and an aliphatic hydrocarbon.
The present invention also provides a method for improving the solder wettability of the plating surface, wherein the solder wettability improving treatment agent is applied to a tin or tin alloy plating surface layer.
[0005]
Examples of the diterpenic acid used in the solder wettability improving treatment agent of the present invention include rubenic acid, agatendicarboxylic acid, pimaric acid, abietic acid, neoabietic acid, levopimaric acid, iso-d-pimalic acid, podocarpic acid, agaricic acid, etc. The 1 type (s) or 2 or more types of mixture can be mention | raise | lifted. Natural rosin is also a mixture of this diterpenic acid and is contained therein. Of these, pimaric acid and abietic acid are preferred. Examples of the derivative compound of diterpenic acid include an esterification reaction product of diterpenic acid with an alcohol having 1 to 18 carbon atoms, preferably 1 to 6 carbon atoms such as methanol, ethanol, propanol, butanol and diethylene glycol. it can. Specific examples include methyl abietic acid, diethylene glycol abietic acid, diethylene glycol 2-hydroabietic acid, and the like.
The solder wettability improving treatment agent of the present invention can contain these diterpenic acids or derivatives thereof in any amount, but preferably contains 0.01 g / L to 0.5 g / L of these, More preferably, it is 0.1 g / L to 0.4 g / L.
[0006]
Examples of the aliphatic carbohydrate used in the solder wettability improving treatment agent of the present invention include oils that are liquid at room temperature mainly composed of paraffinic hydrocarbons, and are preferably paraffin wax and machine oil. The solder wettability improving treatment agent of the present invention can contain these aliphatic carbohydrates in any amount, but preferably contains 0.01 g / L to 2 g / L, more preferably 0. .1 g / L to 0.5 g / L.
The solder wettability improving agent of the present invention is preferably in a liquid state at room temperature, and particularly preferably formed by dissolving the above components in a volatile solvent. As the solvent, alcohols such as methanol, ethanol, propanol and isopropanol are preferable.
In order to uniformly disperse the above components, the solder wettability improving treatment agent of the present invention preferably contains a nonion, a cation, an anion and an amphoteric surfactant. The concentration of these nonions, anions, cations and amphoteric surfactants is preferably 0.01 g / L to 5 g / L, more preferably 0.1 g / L to 2 g / L. Moreover, general corrosion inhibitors, such as benzotriazole and benzimidazole, can also be added as needed.
[0007]
The solder wettability improving treatment agent of the present invention is, for example, plated on a metal substrate such as phosphor bronze or 42 alloy, or on a base plating layer (for example, nickel plating or copper plating) formed by plating. Then, tin and tin alloy plating are formed and applied to the surface. Here, the tin and tin alloy plating method can be performed, for example, by the method described in JP-A No. 06-340994. The tin alloy plating is preferably plating of an alloy mainly containing tin and containing any of copper, silver, bismuth, zinc, and indium. Although the thickness of plating can be made arbitrary, it is preferably 0.5 to 20 μm.
In addition, the improvement of solder wettability can be easily measured by the meniscograph method described in JIS-C0053-1990.
EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to the following Example.
[0008]
【Example】
Example 1
Natural rosin 0.2 g / L as diterpenic acid derivative, ISO VG 2 machine oil 0.2 g / L specified in JISK2238 as machine oil, nonionic surfactant polyoxyethylene nonylphenyl ether 0.5 g / L as dispersant Was dissolved in isopropyl alcohol to prepare the solder wettability improving treatment agent of the present invention.
On the other hand, a 3216-size chip resistor external silver electrode portion was plated with a base nickel plating of 2 μm, and a 5 μm tin single plating film was formed thereon. The portion having the tin plating film was immersed in the solder wettability improving agent and dried.
[0009]
Example 2
A diterpenic acid derivative, 0.2 g / L methyl abietic acid, a paraffin wax with 25 carbon atoms, 0.2 g / L, a nonionic surfactant dipentyl sulfosuccinate ester salt, 0.5 g / as a dispersant, are dissolved in isopropyl alcohol, The solder wettability improving treatment agent of the invention was prepared.
On the other hand, an external silver electrode portion of 1608 size chip resistor was plated to form a base nickel plating of 2 μm, and a 5 μm tin-bismuth alloy plating film was formed thereon. The portion having the tin alloy plating film was immersed in the solder wettability improving agent and dried.
[0010]
Comparative Example 1
A 3216-size chip resistor external silver electrode portion was plated with a base nickel plating of 2 μm, and a 5 μm tin single plating film was formed thereon. The post-treatment of this film was limited to washing with water only.
[0011]
Comparative Example 2
An external silver electrode portion of 1608 size chip resistor was plated to form a base nickel plating of 2 μm, and a 5 μm tin-bismuth alloy plating film was formed thereon. The post-treatment of this film was limited to washing with water only.
[0012]
When the chip resistors of Examples 1 and 2 and the chip resistors of Comparative Examples 1 and 2 were each subjected to a solder wettability test by the meniscograph method, the chip resistor of Comparative Example 1 was wet immediately after plating. The time was 0.9 seconds, and in Comparative Example 2, it was 0.5 seconds. In addition, this wet time shows that wettability is so good that time is short.
On the other hand, the wetting time of Comparative Example 1 after steam aging was 5 seconds under the condition of 100 ° C.-100% -16 Hr, and 1.8 seconds in Comparative Example 2.
[0013]
On the other hand, the wetting time immediately after plating of the chip resistor of Example 1 was 0.7 seconds, and the chip resistor of Example 2 was 0.3 seconds. Further, the wetting time of the chip resistor of Example 1 after steam aging under conditions of 100 ° C.-100% -16 Hr is 2.3 seconds, and the wetting time of the chip resistor of Example 2 is 1.5 seconds. there were.
From the above results, it can be seen that according to the present invention, the solder wettability of the lead-free tin or tin alloy plating surface can be improved.
[0014]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the solder wettability of the surface layer which has as a main component the tin which does not contain lead formed by the plating process on the metal base material or the base plating layer formed by the plating process can be improved significantly. .

Claims (5)

A treatment agent for improving solder wettability of a lead-free tin or tin alloy plating film, comprising diterpenic acid or a derivative thereof , a liquid at room temperature mainly composed of paraffinic hydrocarbons, and a surfactant .   The treatment agent according to claim 1, wherein the derivative of diterpenic acid is a diterpenic acid ester or a hydrogenated product thereof.   The treatment agent according to claim 1 or 2, which is dissolved in a volatile solvent. A solder wettability improving method according to any one of claims 1 to 3, wherein the solder wettability improving agent according to any one of claims 1 to 3 is applied to a lead-free tin or tin alloy plating surface layer.   The method according to claim 4, wherein the tin alloy plating is plating of an alloy mainly containing tin and containing any of copper, silver, bismuth, zinc, and indium.