KR100796891B1 - Sealing agent, method of sealing and printed circuit board treated with the sealing agent - Google Patents

Abstract

The present invention provides a sealing treatment agent, a sealing treatment method, and a printed circuit board treated with the sealing treatment agent, having a corrosion resistance higher than that of the related art and having no deterioration in solder wettability, by treating the product without problems of environmental pollution. .

Seal which contained 0.001 to 0.1 wt% of surfactant and 0.01 to 1 wt% of heterocyclic compound containing a mercapto group or its salt in total, and 0.01-1 wt% of surfactant in total, and adjusted the pH of a solution to 10 or less range A ring treatment agent, a sealing treatment method using the same, and a printed circuit board treated with the treatment agent.

Description

SEALING AGENT, METHOD OF SEALING AND PRINTED CIRCUIT BOARD TREATED WITH THE SEALING AGENT}

The present invention relates to a sealing agent for sealing a gold or gold alloy plating material having a sealing agent, in particular, nickel or nickel-containing alloy plating of a metal material as a base material, a sealing treatment method, and a treatment agent thereof. It relates to a processed printed board.

Background Art Conventionally, in the electronic component industry, gold plating has been used for contact portions of electronic devices that require high reliability such as computers and communication devices.

In recent years, in the situation where miniaturization, high density, and high reliability of electronic devices are required, the rate of plating gold on electronic components (connectors, switches, printed circuit boards, etc.) is increasing.

Generally, gold plating is performed after performing nickel plating on a base material of copper system as base plating.

In recent years, economics are often required for electronic devices. In the gold plating described above, since gold is expensive, it is common to reduce the thickness by reducing the thickness of the gold plating.

However, when the gold plating is thinned, the pinholes in the film increase exponentially, and the corrosive substances (moisture, sulfide, chloride, etc.) in the air invade the contact portions of gold and nickel in the pinholes, thereby forming a local battery. The base and the material are corroded. This corrosion product precipitates on the surface of gold plating, causing problems such as deterioration of contact resistance.

As a method of solving such a problem, the sealing process is generally performed. There are an organic type and an inorganic type in the sealing treatment. Organic systems generally have a problem from the viewpoint of the effects on the environment such as the impact on the human body and the destruction of the ozone layer, since a halogen-based organic solvent is generally used as the solvent. Inorganic systems are well known for the chromate method, but in addition to the fact that the contact resistance increases, the solution contains hexavalent chromium, so that the influence on the human body and the environment becomes a problem.

In order to cope with these problems, an aqueous sealing treatment agent is proposed in which an organic inhibitor is solubilized in water with a surfactant and an emulsifier.

For example, Patent Document 1 discloses an aqueous sealant containing one or two or more selected from the group consisting of specific benzotriazole-based compounds, mercaptobenzothiazole-based compounds and triazine-based compounds as inhibitors, lubricants, and emulsifiers. Ring treatment agents are disclosed.

In addition, Patent Document 2, an aqueous sealing treatment containing one or two or more selected from the group consisting of a benzotriazole compound, a mercaptobenzothiazole compound and a triazine compound as an inhibitor, a surfactant, and an amine compound. I am disclosed.

Including the said patent, since the conventional sealing treatment agent is mainly used for contact uses, such as a connector, it was necessary to provide insertion property. This required characteristic is achieved by applying a lubricity component to the film, and furthermore, this active ingredient serves as a barrier to corrosion components in the atmosphere, thereby providing corrosion resistance.

However, when the conventional sealing treatment agent is used for the pad portion of the printed board, since the flux or the solder alloy applied for the purpose of improving the wettability is peeled off, there is a problem that the solder wettability of the pad portion is greatly deteriorated.

Patent Document 1: Japanese Patent Publication No. 2804453

Patent Document 2: Japanese Patent Publication No. 2003-129257

Disclosure of the Invention

Therefore, there is a need for a sealing treatment agent and a sealing treatment method having a corrosion resistance higher than that of the related art and no deterioration of the solder wettability by treating it without problems of environmental pollution. An object of the present invention is to provide an improved sealing treatment agent and sealing treatment method capable of satisfying such a demand, and a printed circuit board treated with the treatment agent.

The present inventors earnestly examined in order to solve the said problem, and came to invent the sealing treatment agent shown below and the sealing treatment method using the same. That is, this invention is as follows.

(1) 0.001 to 0.1 wt% of a heterocyclic compound containing a mercapto group or a salt thereof, or 0.001 to 0.1 wt% in total and a surfactant of 0.01 to 1 wt% in total, and the pH of the solution is adjusted to 10 or less. One sealing treatment.

(2) The sealing agent as described in said (1) characterized by adjusting the pH of the said solution to the range of 8-10.

(3) The sealing treatment method is performed using the sealing treatment agent as described in said (1) or (2).

(4) A printed circuit board, which is processed using the sealing treatment agent according to the above (1) or (2).

Implement the invention  Best form for

As for the 1st essential component of the sealing treatment agent of this invention, 1 type (s) or 2 or more types of the heterocyclic compound containing a mercapto group or its salt is selected, and 0.001-0.1 wt% in total in a processing agent. It is contained. These compounds react with nickel, which is a base metal inside the gold plated pinhole, to form a complex compound, and the pinhole is filled by the complex compound. As a result, the corrosion resistance of the gold plated is improved.

The heterocyclic compound containing a mercapto group used in the present invention is preferably a compound having a 5-membered heterocycle or a 6-membered heterocycle containing at least one nitrogen, and may be condensed with an aromatic ring. More preferably, the compound represented by a following formula is mentioned. Moreover, these salts (sodium salt, potassium salt, ammonium salt, amine salt, etc.) can also be used.

[Formula 1]

The addition amount of these compounds is in the range of 0.001 to 0.1 wt%, and the sealing treatment effect is not recognized at less than 0.001 wt%, and when it exceeds 0.1 wt%, adverse effects on contact resistance are recognized. Preferably it is 0.005-0.05 wt%.

By adding 0.01-1 wt% of surfactant, it was found that the corrosion resistance improved. This is considered to be because surfactant lowers the surface tension of water and improves the permeability of the heterocyclic compound containing the mercapto group to a pinhole, or its salt.

If the amount of the surfactant added is less than 0.01 wt%, sufficient permeability into the pinholes described above cannot be obtained and sufficient corrosion resistance cannot be obtained. Moreover, when it exceeds 1 wt%, the washing | cleaning effect which surfactant has becomes strong, and since adsorption of the heterocyclic compound containing a mercapto group or its salt is inhibited, sufficient effect cannot be acquired.

Surfactant can select and use 1 type (s) or 2 or more types of commercially available anionic, cationic, nonionic, and amphoteric surfactants suitably. When using the pH of a solution especially in the range of 8-10, it is preferable to select suitably 1 type, or 2 or more types of anionic type, nonionic type, and amphoteric surfactant, and to use. Especially, in anionic surfactant, the ethylene oxide addition product (molecular number 6-12 of ethylene oxide) of nonylphenol, and the intermediate alcohol ethylene oxide addition product (molecular weight 6-12 of ethylene oxide) are especially preferable. Moreover, in anionic surfactant, a sulfate type and a phosphate ester type are especially preferable.

The sealing agent of Unexamined-Japanese-Patent No.2804453 contains a lubricant and an emulsifier, forms a water repellent film, and provides lubricity and corrosion resistance. Moreover, since the sealing surface agent of Unexamined-Japanese-Patent No. 2003-129257 shows a water-repellent metal surface by adding an amine compound, corrosion resistance is improving. However, when the metal surface becomes water repellent, the flux and the solder alloy applied for the purpose of improving the wettability are peeled off, so that the solder wettability is greatly deteriorated.

Since this invention does not contain the component which gives water repellency to the metal surface demonstrated above, solder wettability does not deteriorate.

In addition, although deterioration of corrosion resistance is a concern because of the low water repellency, in the present invention, the penetrating action of the surfactant promotes formation of a complex of a heterocyclic compound containing a mercapto group or a salt thereof in the pinhole. In addition, it turns out that corrosion resistance more than equivalent to the conventional sealing treatment agent can be obtained by making pH of a solution into 10 or less.

The relationship between the pH of the solution and the corrosion resistance is unclear, but the corrosion resistance improved as the pH became more acidic than 10. Moreover, when using pH in the range of 8-10, it turned out that the maximum corrosion resistance can be provided.

When the pH of the solution is 10 or less, it is essential, but when the pH is 7 or less, when the concentration of the heterocyclic compound containing a mercapto group or the salt thereof is high, the heterocyclic compound containing a mercapto group over time or Since the precipitation of the salt may occur, it is preferable to use in the range of pH 8-10 also from a bath life and process control.

It is expected that the pH of the sealing treatment solution changes during use by the addition of the liquid from the previous step to the sealing treatment tank. In order to minimize this pH fluctuation, it is preferable to add a pH buffer. Examples of the substance having a pH buffering ability in the pH range of the present invention include alkali metal salts of pyrophosphoric acid, alkali metal salts of tripolyphosphoric acid, alkali metal salts of boric acid, alkali metal salts of tetraboric acid, alkali metal salts of glutamic acid, ammonia water, diethanolamine, and diethylene. Triamine etc. are mentioned.

Although the sealing treatment agent of this invention has the above-mentioned component, it can select suitably from the organic solvent which does not contain water or halogen, such as ethanol, acetone, normal paraffin, as a solvent. However, in consideration of economic efficiency, flammability, etc., water is optimal as a solvent. In the case where the solvent is water, when the temperature of the solution is heated to 40 to 80 ° C., the emulsification of the components into water becomes more rapid, and the drying of the material after the treatment becomes easier.

The treatment method may be any method such as immersing a plated product in the treatment agent, spraying or applying the treatment agent. However, in the present invention, regardless of the shape of the plated product, whether it is a plate, a file, or a press part, if it is immediately after plating, that is, a continuous line, processing in the line has a high effect of improving various functions of the sealing treatment. It is also effective to seal the plated product with the sealing agent of the present invention after processing such as pressing. Even in the case of a metal material subjected to sealing after plating, many of the functions of the sealing treatment are lost in the step of washing the press oil adhered by subsequent press work. In that case, it is effective to perform sealing again.

In addition, when the printed circuit board is processed using the sealing agent of the present invention, a printed board having a corrosion resistance equal to or higher than the conventional one can be obtained without deteriorating the solder wettability.

An Example is given to the following and this invention is demonstrated in detail.

Example  1 to 9 and Comparative example  1 to 8

On the phosphor bronze substrate for spring (C5210, 25 mm x 20 mm x 0.4 mm), 1 micrometer of nickel plating was performed by the watt bath, and 0.1 micrometer of gold plating was performed by the cyan bath on it.

This gold plated substrate was treated with the sealing agent shown by the composition of Table 1 on condition of bath temperature of 50 degreeC, and immersion time 20 second, and water-washed and dried, and the sealing coating film was formed on the gold plated. In addition, ion-exchange water was used for the solvent of the sealing agent.

The following evaluation was performed about the board | substrate which performed the sealing process. The results are shown in Table 1.

[Salt spray test]

About these board | substrates, the salt spray test (it conformed to JISZ2371) was performed for 24 hours, and corrosion resistance was evaluated.

Evaluation standard

○: Almost no corrosion

△: dark brown corrosion spots

×: Green corrosion point (cyan) is seen everywhere

[Solder wettability]

For these substrates, flux (RM-26, produced by Tamura Chemical Co., Ltd.) was diluted twice with isopropyl alcohol on the whole surface and allowed to stand for 10 minutes, followed by solder balls (sparkling ball S, Sn-37). 5% Pb, 0.6mm Ø, Senju Metal Industry Co., Ltd.), and heated (preheated) on a hot plate kept at 150 ° C. for 2 minutes, followed by heating for 30 seconds on a hot plate kept at 230 ° C. Was carried out. The solder wettability was evaluated based on the area where the solder ball after heating was wet and spread, and the area where the solder ball was not subjected to sealing was wet and spread (n = 5).

Solder Wetting Rating Criteria

(Circle): Area where the solder ball gets wet and spread> Untreated wet area spreading × 0.95

X: Area where the solder ball wets and spreads <Untreated wet spread area × 0.7

Moreover, as a comparative example, the board | substrate (Comparative Example 7) which performed the process disclosed by Unexamined-Japanese-Patent No. 2804453, and the board | substrate which performed the process disclosed by Unexamined-Japanese-Patent No. 2003-129257 were also evaluated also. The composition is as follows. In addition, Table 1 shows the evaluation test results.

Comparative Example 7 (sealing treatment agent described in Japanese Patent Publication No. 2804453)

   Inhibitor: Benzotriazole 0.01wt%

   Lubricant: 0.3wt% oleic acid

   Emulsifier: lauryl acid phosphate monoester 0.3wt%

Comparative Example 8 (Sealing treatment agent described in Japanese Patent Laid-Open No. 2003-129257)

   Inhibitor: Benzotriazole 0.05wt%

   Amine compound: triethanolamine 1wt%

   Phosphate ester surfactant: EN-2P 0.1wt%

TABLE 1-1

TABLE 1-2

As is apparent from the above results, the sealing agent of the present invention does not contain a substance polluting the environment, and furthermore, the plating material treated with the sealing agent of the present invention has corrosion resistance equal to or higher than that of the prior art. It does not deteriorate solder wettability.

Claims (4)

Seal which contained 0.001 to 0.1 wt% of surfactant and 0.01 to 1 wt% of the heterocyclic compound containing a mercapto group, or its salt in total, and 0.01-1 wt% of surfactant in total, and adjusted the pH of a solution to 10 or less range Ring treatment agent. The pH of the said solution was adjusted to the range of 8-10, The sealing treatment agent of Claim 1 characterized by the above-mentioned. The sealing treatment method of Claim 1 or 2 which apply | coats the sealing treatment agent to a plated article, or immerses this plating article in the said seal treatment agent, and performs the sealing process. It was processed using the sealing treatment agent of Claim 1 or 2, The printed circuit board characterized by the above-mentioned.