JPH02301588A - Tin, lead or tin-lead alloy electroplating bath and electroplating method - Google Patents

Abstract

PURPOSE:To enable satisfactory Sn, Pb or Sn-Pb alloy plating in a specified pH range by adding a complexing agent such as ascorbic acid, 2-ketogluconic acid, sorbitol, sorbose, glucose or glucuronic acid to a plating bath. CONSTITUTION:One or more kinds of complexing agents selected among ascorbic acid, isoascorbic acid, dehydroascorbic acid, 2-ketogluconic acid, sorbitol, sorbose, glucose' glucuronic acid, gulonic acid, gulonolactone, 2,3- diketogulonic acid and salts of them are added to a plating bath contg. Sn and/or Pb ions. A satisfactory Sn, Pb or Sn-Pb alloy plating film is formed in the pH range of 2-9 and the plating bath can be used to plate electronic parts in a wide current density range with high current efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel tin, lead, and tin-lead valley gold electroplating bath and an electroplating method using an acid bath.

[Prior Art and Problems to be Solved by the Invention] Tin and tin-lead alloy electroplating have been widely used in the fields of light electrical and electronic industries, mainly for soldering properties.

Conventionally, the electroplating baths used for such electroplating of tin and tin-lead alloys have been mainly sulfuric acid baths, organic sulfonic acid baths, or boronic acid baths, which are strongly acidic baths with a pH of 1 or less.

These strong acid baths do not pose any particular problems in use if the object to be plated is copper, steel, or the like. However, recently, many electronic components are made of composite materials such as metal, ceramic, glass, and plastic as materials to be plated.For example, there are cerdip-type IC packages and chips sealed using lead glass. Capacitors are now being used. Furthermore, there are an increasing number of electronic components in which circuits are formed by depositing aluminum on ceramic and etching it. If tin or tin-lead alloy plating is applied to these parts from the above-mentioned strong acid bath, the ceramic, glass, or vapor-deposited aluminum in the parts will be eroded, and furthermore, the problem of bridging, where the plating will adhere to the insulator, will occur. was there.

Such problems can be solved by adjusting the pH of the plating bath to 2 to 9. However, simply adjusting the pH of the plating bath to 2~
If the value is 9, tin ions and lead ions become hydroxides and precipitate, making plating impossible.

On the other hand, as tin and tin-lead alloy electroplating baths, various baths that can be used within the above pH range and use citric acid, gluconic acid, pyrophosphoric acid, organic phosphonic acid, or their salts have been proposed ( JP-A No. 49-93236, No. 53
-5034, 54-60230, 54-695
No. 33, No. 54-69534 No. 1 No. 57-63689
No. 61-194194, etc.), and furthermore, pH 2 ~
A plating bath that can perform tin, lead, or tin-lead alloy plating well in the range of 9 is desired.

The present invention was made in view of the above circumstances, and provides a tin, lead, and tin-lead alloy plating bath that is stable in the pH range of 2 to 9, has high current efficiency, and can be used in a wide current density range, and the plating bath. The purpose of the present invention is to provide an electroplating method that can be used.

[Means and effects for solving the problem] As a result of intensive studies to achieve the above object, the present inventors have discovered that ascorbic acid and isoascorbic acid can be used as complexing agents for plating baths containing tin ions and/or lead ions. acid, or its synthetic intermediate or oxidation product, i.e. dehydroascorbic acid, 2-
Ketogluconic acid, sorbitol, sorbose, glucose, glucuronic acid, gulonic acid, gulonolactone.

By using 2.3-diketogulonic acid or its salts, it is stable in the pH range of 2 to 9, does not generate tin or lead hydroxides, and is suitable for ceramics, lead glass,
Electronic parts made of composite materials with metals such as vapor-deposited aluminum can be plated without corrosion, and baths containing these complexing agents have high current efficiency, can be used over a wide current density range, and provide good plating. It was discovered that a film can be obtained, and the present invention was completed.

Therefore, the present invention provides ascorbic acid, isoascorbic acid, dehydroascorbic acid, 2-ketogluconate, etc. as a complexing agent in a tin, lead or tin-lead alloy plating bath containing tin ions, lead ions, or tin ions and lead ions. Acid, sorbitol, sorbose.

A tin, lead or tin-lead alloy electroplating bath, characterized in that it contains one or more selected from glucose, glucuronic acid, curonic acid, chronolactone, 2,3-diketogulonic acid, and salts thereof; and a method for electroplating tin, lead or tin-lead alloy, which comprises electroplating an object to be plated using the above plating bath.

The present invention will be explained in more detail below.

In the plating bath of the present invention, the metal salt that provides tin ions or lead ions is not particularly limited, but tin salts include tin sulfate, tin chloride, tin nitrate, tin methanesulfonate, tin alkanolsulfonate, and silver phenolsulfonate. , tin borofluoride, tin acetate, tin oxide, etc. In this case, the tin salt may be a divalent tin salt or a tetravalent tin salt. On the other hand, examples of lead salts include lead nitrate, lead acetate, lead borofluoride, lead methanesulfonate, lead chloride, lead sulfate, and lead oxide.

The concentration of the tin ions and lead ions in the plating bath is selected as appropriate, but is usually 0.5 to 2 oog/l, more preferably 1 to 100 g/l.

The present invention uses ascorbic acid as a complexing agent in a plating bath containing such tin ions and/or lead ions.

Isoascorbic acid, dehydroascorbic acid.

2-ketogluconic acid, sorbitol, sorbose.

One or more selected from glucose, glucuronic acid, gulonic acid, chronolactone, 2,3-diketogulonic acid, and salts thereof are blended. Note that examples of the salt include alkali metal salts, ammonium salts, tin salts, lead salts, and the like.

The amount of these complexing agents added is also selected variously, but usually 3 to 8
00g/f, more preferably 40-400g/j
! It is.

In addition to the above-mentioned complexing agent, the plating bath of the present invention may contain other complexing agents, such as citric acid and pyrophosphoric acid.

There is no problem in adding gluconic acid or salts thereof.

The plating bath of the present invention further contains a conductive salt if necessary.

pH buffering agents, surfactants, brighteners, etc. can be added.

Here, as the conductive salt, ammonium methanesulfonate, ammonium sulfate, ammonium chloride, sodium sulfate, potassium chloride, ammonium acetate, ammonium ascorbate, sodium alkanolsulfonate, sodium phenolsulfonate, etc. can be used. Plating voltage can be lowered by adding
Uniform electrodeposition can be improved. Its blending amount is 0
~aoog//2, preferably 10~
800 g/l, more preferably 50 to 300 g/f.

Further, as the pl+buffer, boric acid, ammonium chloride, ammonium sulfate, and ammonium acetate are used.

Examples include sodium phosphate, potassium phosphate, sodium borate, potassium borate, sodium formate, potassium formate, ammonium citrate, and sodium citrate. The amount added is 0 to 100g/1. , especially 10
It is preferable to set it as 50 g/l.

Further, as the surfactant, nonionic, cationic, zwitterionic, and anionic surfactants can be used. In this case, these surfactants are not particularly limited,
There are various selections, but from the viewpoint of salting out, those with a high deposition point or those with no deposition point are preferred.

More preferably, the nonionic surfactant is one obtained by adding 15 moles of ethylene oxide to nonylphenol, or an alkyl β-naphthol (an alkyl group having 1 to 2 carbon atoms).
5) with 25 moles of ethylene oxide added thereto, polynuclear phenol ethoxylates (for example, Adecatol PC-10, PC-1, 3 manufactured by Asahi Denka Kogyo Co., Ltd.), and the like. In addition, as the cationic surfactant, those obtained by adding 10 moles of ethylene oxide to laurylamine, and those obtained by adding 15 moles of ethylene oxide to beef tallow alkylamine are preferably used. Furthermore, as the amphoteric ionic surfactant, imidapurine type surfactants, especially those represented by the following formula (wherein R1 is an alkyl group having 3 to 25 carbon atoms and R2 is an alkyl group having 1 to 18 carbon atoms) are used. (For example, Amogen Nα8 manufactured by Daiichi Kogyo Seiyaku ■) is suitable.

The addition of the above-mentioned nonionic and cationic 9 zwitterionic surfactants has the effect of smoothing and densifying the plating film, but the amount of these surfactants added is 0.01 to 30%.
g/l.

On the other hand, anionic surfactants are particularly effective in eliminating gas pits in plating and increasing the landing point of nonionic surfactants. Acid alkyl esters and those represented by the following formula (%), such as sodium catechol disulfonate, are preferably used. Note that the amount of anionic surfactant added can be 0.1 to 50 g/J2.

If bright plating is required, brighteners are added, but
Examples of brighteners include formaldehyde, acetaldehyde, propionaldehyde, glyoxal, succinaldehyde, capronaldehyde, aliphatic aldehydes such as aldol, benzaldehyde, 1-notyl aldehyde aryl ether, pt-raldehyde, and 1-naphthaldehyde.

Aromatic aldehydes such as salicylaldehyde, veratraldehyde, anisaldehyde, biperonal, and vanillin can be used. Furthermore, sulfanilic acid derivatives, triazine derivatives, acrylic acid, methacrylic acid, crotonic acid,
Other α-unsaturated carboxylic acids and the like can also be used. The amount of these brighteners added is 0.01 to 30 g/l
! , especially 0.03 to 5 g/ffi.

The pH of the plating bath of the present invention is 2 to 9, more preferably 3 to B.
, 5, more preferably 5 to 8. In this case, aqueous ammonia, caustic alkali, etc. can be used to adjust pHegJ1.

When electroplating is carried out using the above plating bath, the power source is required to obtain a matte to semi-bright plating film.
(that part becomes black), it is recommended to use single-phase full-wave or single-phase half-wave rectification rather than complete direct current, three-phase full-wave, or three-phase half-wave rectification, and pulse power sources are also used. On the other hand, when obtaining a bright plating film, it is recommended to use full direct current, three-phase full-wave, or three-phase half-wave rectification rather than single-phase full-wave or single-phase half-wave rectification from the viewpoint of gloss.

The plating bath of the present invention can be used not only for normal rack plating but also for barrel plating, and can also be applied to high-speed plating, through-hole plating, etc., but the plating conditions should be selected depending on the type of plating, etc. According to the plating bath of the present invention, a homogeneous and dense plating film can be obtained over a wide range of current densities. Specifically, the plating temperature is more preferably 10-60° than 5-90″C1.
C, and the cathode current density is O, OO1~30
A/dm", more preferably 0.1 to IOA/dm"
It can be done. Further, stirring can be carried out by rotation of a barrel, cathode locking, pump flow, liquid flow by a resolution machine, air stirring, etc., and in some cases, stirring may be performed without stirring. For the anode, depending on the type of plating bath, metal tin, metal lead, or in the case of tin-lead alloy plating, use a combination of metal tin and metal lead, or a tin-lead alloy depending on the composition of the plating film. However, an insoluble anode may also be used.

In the present invention, the object to be plated is not limited to any object as long as it can be electroplated, but the present invention is particularly suitable for plating electronic components made of composite materials such as metals, ceramics, and glass. It is.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to examples, but the present invention is not limited to the following examples.

[Example 1] Methanesulfonic acid 1st. Tin (as Sn) 10g#! Lead methanesulfonate (as PB) 1 Ascorbic acid 200 Boric acid
30 15 moles of ethylene oxide adduct of beef tallow amine 1 Methanesulfonic acid 100 pH (adjusted with aqueous ammonia) 7 Using a plating bath with the above composition, plating on a copper plate by single-phase full-wave rectification at 40°C, Dx I A
Plating was carried out for 10 minutes under the condition of "/dm".

As a result, a smooth, dense, white semi-glossy tin-lead alloy plating film was obtained. The PB content in the film was 10%, and the current efficiency was 99%.

In addition, the above plating bath gives DK to IC parts with lead glass.
Plating was carried out to a thickness of about 7 μm using IA/di”, and a good white semi-gloss tin-lead alloy plating film was obtained without corroding the lead glass.

In addition, after zinc substitution treatment was performed on a temporary ceramic having an aluminum vapor-deposited film by a conventional method, tin-lead alloy plating of 10 μm was performed using the above plating bath, but the vapor-deposited aluminum was not dissolved and eroded. A tin-lead alloy plating film was formed on the vapor-deposited aluminum with good adhesion.

[Example 2] Stannous sulfate (as Sn) 'Og/l
Lead methanesulfonate (as PB) 1 Dehydroascorbic acid 200 Boric acid
30 15 moles of ethylene oxide adduct of beef tallow amine 1 g/2 ammonium sulfate 50 IpH (adjusted with aqueous ammonia) 7 Plating was carried out in the same manner as in Example 1 using a plating bath with the above composition, and the result was the same as in Example 1. The results were obtained.

(Example 3) In the plating bath of Example 1, isoascorbic acid, 2-ketogluconic acid, sorbitol, sorbose, glucose, glucuronic acid, gulonic acid, gulonolactone, and 2,3-diketogulonic acid were used instead of ascorbic acid. When plating was carried out, the same results as in Example 1 were obtained.

[Example 4] Stannous 3-hydroxy-1-propanesulfonic acid (as Sn) 20 g/l Sorbitol 200 Citric acid 3
Ammonium 30 〃Adecatol PC-
103〃 Sodium sulfate 50g, 1 benzalacetone 0.1〃p)l
6 Using the above plating bath, coat the copper plate with complete direct current at 25°C, DK 2 A/d.
Plating was performed for 5 minutes under conditions of m2.

As a result, a smooth, dense, and glossy tin plating film was obtained. Note that the current efficiency was 99%.

In addition, the above plating bath can cause Dx to be applied to IC parts with lead glass.
Plating was carried out to a thickness of about 8 μm at 2 A/dm2, and a good bright tin plating film was obtained without corroding the lead glass.

C Example 5] Lead acetate (as pb) 10g/β
Potassium phenolsulfonate 50 2-ketogluconic acid 150 Zymogen Nα8
3〃N-(3-hydroxybutylidene)-p-sulfanilic acid 0.2〃pH
7,5' Using the above plating bath, 50% plating was applied on a copper plate by single-phase half-wave rectification.
Plating was carried out for 5 minutes under the conditions of °C and Dx 3 A/di2.

As a result, a smooth and dense semi-bright lead plating film was obtained.

Note that the current efficiency was 98%.

〔Effect of the invention〕

According to the present invention, tin is good in the pH range of 2 to 9.

It provides a lead or tin-lead alloy plating film, has high current efficiency, and can be used in a wide current density range, and is therefore suitably used for plating electronic parts.

Applicant: Uemura Kogyo Co., Ltd.

Claims (1)

[Claims] 1. Ascorbic acid, isoascorbic acid, dehydroascorbic acid as a complexing agent in a tin, lead or tin-lead alloy plating bath containing tin ions, lead ions, or tin ions and lead ions; - a tin containing one or more selected from ketogluconic acid, sorbitol, sorbose, glucose, glucuronic acid, gulonic acid, gulonolactone, 2,3-diketogulonic acid, and salts thereof;
Lead or tin-lead alloy electroplating bath. 2. A method for electroplating tin, lead, or tin-lead alloy, which comprises electroplating an object to be plated using the plating bath according to claim 1.