JPH0211678B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a plating bath.

More specifically, the present invention relates to a nickel plating bath with improved solder wettability.

Solder is fused to the plating on the terminals of electronic components, but the plating must have good solder wettability (no solder lumps or pinholes). Flux is generally used as a method to improve solder wettability.
However, flux treatment of plated terminals not only increases the number of steps but also causes staining of parts other than the terminals due to the flux, which is not desirable.

For example, there is a method of using a phosphorus compound or a boron compound as an electroless nickel plating method that improves solder wettability, but these methods do not necessarily provide sufficient solder wettability.

The object of the present invention is to provide a nickel plating bath that does not have these drawbacks.

The present invention adds dichlorophthalic acid and/or tetrachlorophthalic acid to the plating liquid 1, which decomposes, sublimates, or has a high vapor pressure near the melting point of the solder, thereby cleaning the surface of the base metal and improving the wettability of the molten solder. It relates to a nickel metal bath containing 0.1 to 80 g.

More specifically, the present invention provides dichlorophthalic acid and/or which decomposes, sublimates, or has a high vapor pressure near the melting point of the solder in a nickel plating bath, thereby cleaning the surface of the base metal and improving the wettability of the molten solder.
Or, by adding 0.1 to 80 g of tetrachlorophthalic acid to 1 part of the plating solution, a component that has a flux effect with nickel plating can be precipitated or contained in the plating film, thereby eliminating the flux process, which was conventionally performed as a separate process, and making it possible to use other than terminals. The purpose is to eliminate contamination of the parts and provide sufficient solder wettability to the plating.

The nickel plating bath of the present invention can be applied to both electroless and electrolytic nickel plating baths, and reducing agents, PH adjusters, buffers, complexing agents, promoters, stabilizers, improvers, etc. can be added to the plating bath. There is no restriction on addition as long as it does not inhibit the flux effect.

The content of dichlorophthalic acid and/or tetrachlorophthalic acid is as follows:
If the weight is outside this range, the life of the nickel plating bath will be short and the flux cannot be deposited to an appropriate thickness.

The present invention will be explained below with reference to Examples.

Example 1 Electroless nickel plating solution (Schuman nickel plating solution manufactured by Nippon Kanisen) was diluted by adding 4 parts of distilled water, and 25 g of dichlorophthalic acid, which imparts a flux effect, was added to prepare an electroless nickel plating bath.

Separately from the above, 2 parts of distilled water was added to 2 parts of 35% first class reagent hydrochloric acid to prepare an acid treatment bath.

Furthermore, in addition to the above, distilled water 2 was added to the red bath 2 to form an activation bath. Next size is 10cm
Clean a corner, 1mm thick copper plate with acetone and under running water.
After washing with water for 20 minutes, it was immersed in the aforementioned acid treatment bath for 2 minutes, and then washed with running water for 10 minutes. Further, the copper plate was immersed in the above-mentioned activation bath for 10 minutes and then washed in running water for 5 minutes to obtain an activated copper plate.

Next, the electroless nickel plating bath described above was heated to 80°C, and the activated copper plate was immersed in this bath for 10 minutes while moving, and then washed under running water for 20 minutes.
Next, it was immersed in acetone, dried and plated.

On top of this plated copper plate, a 9cm square
A 0.1 mm thick high-temperature solder (90% by weight lead, 10% by weight tin) was placed on it and heated in a hydrogen atmosphere, and this high-temperature solder was reflowed (cast). Heating conditions: 10 minutes
After raising the temperature to 260℃, hold it at that temperature for 10 minutes, and then heat it for another 5 minutes.
The temperature was raised to 320°C for 2 minutes, held at that temperature for 2 minutes, and then rapidly cooled to 80°C for 5 minutes. When the appearance after solder fusion was observed, it was found that the solder was uniformly cast on the upper surface of the copper plate, and no solder lumps or pinholes were observed.

Comparative Example 1 The activated copper plate of Example 1 was plated in the same manner as in Example 1 using a nickel plating bath in which dichlorophthalic acid was not added to an electroless nickel plating solution (Shermany nickel plating solution manufactured by Nippon Kanizen).

High-temperature solder was cast on this plated copper plate using the same method and conditions as in Example 1.

When the appearance after solder fusion was observed, the solder did not spread uniformly and sink marks were observed, and disk-shaped lumps and pinholes with a diameter of 2 to 3 mm were formed.

Example 2 Nickel sulfate 240g/, nickel chloride 45g/
was dissolved in distilled water from step 4 to prepare a matte nickel plating solution, and then 25 g of tetrachlorophthalic acid was added to this matte nickel plating solution to prepare an electrolytic nickel plating bath.

Next, the electrolytic nickel plating bath described above was heated to 50°C, and the activated copper plate of Example 1 was immersed in this bath, and while being moved, a current density of 4 A/dm ² was applied.
It was plated for 10 minutes, then washed under running water for 20 minutes, then immersed in acetone, dried, and plated.

High-temperature solder was cast on this plated copper plate using the same method and conditions as in Example 1.

When the appearance after solder fusion was observed, the solder was uniformly cast on the upper surface of the copper plate, and no solder lumps or pinholes were observed.

According to the nickel plating bath of the present invention, a flux effect acts during solder casting, suppressing sink marks and the like and significantly improving solder wettability.

Claims (1)

[Claims] 1 To the plating liquid 1, add 0.1 to 10% of dichlorophthalic acid and/or tetrachlorophthalic acid, which decomposes, sublimates, or has a high vapor pressure near the melting point of the solder, cleans the surface of the base metal, and improves the wettability of molten solder. Nikkelmetsuki bath containing 80g.