JPS61276990A - Gold electroplating solution - Google Patents

Abstract

PURPOSE:To improve the uniform electrodepositing property of gold plating by adding an amine compound having pyrrolidine, piperazine, piperidine or pyridine as the skeleton to a gold electroplating soln. contg. a soluble gold salt and a conductive salt. CONSTITUTION:An amino compound having pyrrolidine, piperazine, piperidine or pyridine as the skeleton such as N-aminopyrrolidine, N-aminopiperazine, N-aminopiperidine or 2-aminopyridine is added to a gold electroplating soln. contg. >=about 2g/l (expressed in terms of metallic gold) soluble gold salt such as potassium gold cyanide and a conductive salt such as an alkali metallic salt of an inorg. acid such as phosphoric acid to improve the uniform electrodepositing property of gold plating. The preferred amount of the amino compound added is about 0.1-100g/l. Thus, the amount of gold depositing on an article in excess is considerably reduced to reduce the cost and to improve the quality, and the life of the gold electroplating soln. is prolonged.

Description

[Detailed Description of the Invention] [Field of Industrial Application] Does the present invention apply to electrolytic gold plating? Second, to be more specific, I will focus on gold plating liquids that have excellent uniform electrodeposition properties.

[Conventional technology]

Gold plating is widely used in the semiconductor industry for various types of IC packages, etc. However, in the case of products with many uneven shapes, variations in the plating thickness due to the amount of each plated object and the plating trend can occur. Listening to people 1.1. /+A gold plating bath that provides uniform plating thickness distribution is requested.

Since gold plating is expensive, it is very difficult to reduce the variation in the plating thickness of the object to be plated because it is expensive. It is necessary to set it to C so that it does not occur (for example, JP-A-56-844!) 5
and 56-108892). However, in electrolytic plating, gold tends to be deposited multiple times on the convex parts of the object to be plated where the current is concentrated, making it impossible to obtain a uniform plating thickness. With conventional gold plating solutions, uniform electrodeposition as determined by Field's formula is only about 5% (maximum 1%).For this reason, variations in the plating thickness can occur, resulting in thicker electrodepositions of less than 1%. In some parts, the characteristics are adversely affected when CI rear is attached, and in the through ball, the plating is thick or thin at the edges, and the heat resistance (41 and solder) is good. Depending on the product, the problem of poor uniform electrodeposition is not limited to the cost I/me, but extends to the 'I'f (/I) problem, and tampering is required.

[Problem that the invention seeks to solve]

The present invention aims to solve the above-mentioned problems of the prior art in attaching metal ν. That is, the present invention
By developing a gold plating solution with a liquid composition that makes the plating uniform between each plate and two pieces or between the same plated objects depending on the distribution of current density, it is possible to The purpose is to give objects a uniform gold plating with a thickness of 7.5mm, to improve properties and reduce costs.

[Means for solving the problem] According to the present invention, an electrolytic gold plating solution consisting of a soluble gold salt and a conductive salt is provided, and this solution ε,1, uniform electrodeposition of gold plating is It is characterized by containing an amine compound having a pyrrolidine, piperazine, piperidine or pyridine skeleton that has an improving effect.

That is, according to the present invention, pyrroline, piperazine, and piperidine are added to the electrolytic gold plating solution containing a soluble gold salt such as gold potassium cyanide, generally in an amount of 2 g/ρ or more as metal gold. 1. Amination of biriΣnon'111M i) 9.
(L was released because it was able to achieve uniform electrodeposition.

Examples of soluble gold salts useful for this investigation include gold potassium cyanide, (11! gold sulfate, etc.). , diphosphoric acid, oxalic acid, or alkali metal salts, particularly preferably potassium salts.

Examples of amine compounds having a pi(-I lysine skeleton useful in the present invention) include N-aminopyrrolidine, N-aminomethylbi1''lysine, N-aminomethylbi``Ilysine, etc.Amine compounds having a piperazine skeleton include ,
Examples include N-aminopiperazine, N-aminoethylpiperazine, N,N-diaminopiperazine, and the like. Also,
As amine compounds with piperidine 1-1 41,
Examples include N-aminopiperidine, N-aminomethylpiperidine, N-aminoethylpiperidine, etc., and examples of amine compounds having a pyridine skeleton include 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, etc. be. And these compounds have a concentration of 0.1 to 10
0g/l especially i~30g/l! ') is preferably contained in the plating solution of the present invention.

The electrolytic gold plating solution of the present invention can be easily used for electrolytic gold plating by conventional methods such as rank plating, sheet plating, and barrel plating.

The electrolytic gold plating solution according to the present invention may also contain a crystal modifier such as thallium, lead, or arsenic.

〔Example〕

Next, the present invention will be further explained by examples.

Example 1 Kokugu bottom gold potassium cyanide 12g/i! (as metal gold
8 g/l Citric acid 25 g/Il Dipotassium hydrogen phosphate 75 g#! N-aminopyrrolidine l Om j! / /) Potassium arsenite 2ppm (as arsenic) Gold plating solution with the following composition (pH 6.0, bath'/IA 60'
When Halcel plating was performed at 0.3 A for 5 minutes using C) with moderate stirring, a lemon yellow glossy plating was obtained. In addition, this gold plated number 31゛,
It satisfied the characteristics required for Ic pathogy, such as adhesion and heat resistance, to within 1 minute. The film thickness at four points on this Hull cell panel was measured using a fluorescent X-ray micro film thickness meter, and the uniform electrodeposition was determined using the Feil 1' formula, and found to be 92%.

The uniform electrodeposition property of a gold plating solution obtained by removing the uniform electrodeposition improving agent N-aminopyrrolidine from the above composition was examined in the same manner and found to be 42%.

Example 2 Bath-Gumi J Kana Gold Potassium Cyanide 12 g/I! (8g/ρ as metallic gold) Citric acid 25g/l.

Dipotassium hydrogen phosphate 75 g/7! N-aminoethylpiperazine l rn I! / 1 sulfuric acid Daiichi Kuriu J, (as thallium)] Op p m Gold plating of the above Al1 composition>& (pH 6,0, bath?AX
Hull cell plating was performed in the same manner as in Example 1 using fi O'(: )) and 1 u of lemon yellow semi-bright plating was applied. Incidentally, this gold plating sufficiently met the characteristics required for Ic panogage, such as adhesion and heat resistance. Uniform electrodeposition +z was determined by the J method (same as in Example 1) and was 74%. Also, 1. The uniform electrodeposition property of the gold plating solution with the &Il composition obtained by removing N-aminoethylpiperazine from the above 3.11 composition was 33%.

Example 3 @ &lj nokachi gold potassium cyanide! 2 g/R(
As metallic gold 8g/7 tripotassium citrate 50g/l phosphoric acid
Potassium 50 g/R4-minobiridine 20 g/l Lead acetate (as lead)
5 p p m above K, gold plating? Pj
, (pH 6.0, bath temperature 6 (1'c), Example 1
Hull cell plating was performed in the same manner as in 7. , lemon yellow semi-gloss plating was obtained. On the other hand, this gold plating sufficiently satisfies the characteristics required for IC pano-chi, such as adhesion and heat resistance. The uniform electrodeposition property was determined in the same manner as in Example 1, and was found to be 69%. In addition, the uniform electrodeposition of the gold plate with the composition excluding N-aminoethylpiperazine (Table H) was 27%.
Met. In this example, when the lead acetate was replaced with dried lead complexed with a 3L complexing agent of ET') TA (ethylenediaminetetraacetic acid), the uniform electrodeposition was further improved to 95%.

As explained in 1-1 above, by adding pyrrolidine, piperazine, piperidine, and a compound having a pyridine skeleton to the gold plating solution, uniform electrodeposition improves by about 40 to 50% regardless of the type of crystal modifier. Kotonekakunoko.

Usually, as gold plating and plating solution Kl are used, the concentration of metal impurities in the 4F illusion gold plating solution increases as the molten Y-J comes out from the object to be plated. As the metal impurity concentration increases, the amount of metal impurity eutectoid in gold plating also increases, leading to deterioration of the gold plating characteristics.

Therefore, the lifespan of a gold plating solution is determined by the concentration of metal impurities in the gold plating bath.

In Example 1, in the case of a gold plating solution with a composition excluding N-aminopyrrolidine, the concentration of metal impurities in the plating solution increased by about 1100 pp in total for iron and nickel after one month of use. However, with the addition of N-aminopyrrolidine, the concentration of metal impurities in the plating solution increased by 50 ppm after one month of use, compared to the case without the addition. It was cut in half.

〔Effect of the invention〕

As described above, the gold plating solution according to the present invention can significantly reduce excess gold adhering to products compared to conventional gold plating solutions. Cos I・
You can aim for down. Furthermore, uniform adhesion is improved, resulting in a significant improvement in quality.

In addition, amine compounds also have a corrosion inhibiting effect, so
The amine compound added to the gold plating solution suppresses the substitution reaction between the gold and the plating base. As a result, the rate of increase in the concentration of metal impurities in the gold plating solution is reduced, and the life of the gold plating solution is extended.

Claims (1)

[Claims] 1. An electrolytic gold plating solution consisting of a soluble gold salt and a conductive salt, characterized by containing an amine compound having a pyrrolidine, piperazine, piperidine or pyridine skeleton, which has the effect of improving the uniform electrodeposition of gold plating. Electrolytic gold plating solution.