JPS63161187A - Production of reflow-treated solder plated material - Google Patents

Abstract

PURPOSE:To make the thickness of a film uniform and to improve the quality by using an electroplating bath obtd. by adding a surfactant represented by a prescribed molecular formula to a soln. contg. a free acid component, bivalent Sn and Pb salts when solder plating followed by reflow treatment is carried out. CONSTITUTION:A soln. contg. alkanesulfonic acid and/or alkanolsulfonic acid as a free acid component, and bivalent Sn and Pb salts is prepd. A surfactant represented by the formula [where (a+c)=2-350 and b=11-66] is added to the soln. to obtain an electroplating bath. A layer formed by electroplating in the bath is heated to the m.p. of the layer or above to carry out reflow treatment.

Description

[Detailed Description of the Invention] Field of the Invention The present invention is directed to electroplating a metal strip with solder, which is an alloy of tin and lead, and then subjecting it to a reflow treatment to improve the appearance and uniformity of the film thickness. The present invention relates to a method of manufacturing a reflow solder plating material having excellent quality in terms of.

Ibaraban Conventionally, as a surface treatment method for applying solder plating to metal materials, after electroplating solder on various metal materials, solder is applied to improve the appearance and corrosion resistance of the plating layer. A method is known in which a plating layer is melt-processed, ie, a so-called reflow process is performed.

Conventionally, a borofluoride bath or a phenolsulfonic acid bath has been used as an electroplating bath for applying the solder plating. However, borofluoride in borofluoride baths,
Since the trace amount of phenol contained in the phenolsulfonic acid bath is a polluting substance, there has been a demand for the development of a non-polluting alternative bath.

In recent years, in view of such demands, various low-pollution solder plating baths containing alkanolsulfonic acid or alkanesulfonic acid as a free acid component have been put into practical use.

However, although the reflow treatment of solder plating material electrodeposited from the borofluoride bath described above has been carried out for a long time and is technically established, At present, no satisfactory technology has yet been established for producing reflow solder plated materials using a solder bath.

■ However, the present inventors performed plating using a solder plating bath containing low-pollution alkanesulfonic acid or alkanolsulfonic acid as the free acid, and then performed reflow treatment to achieve high-quality reflow. As a result of research on a method for manufacturing solder plating materials, it was found that a specific surfactant was added to a solution containing a free acid component of alkanesulfonic acid or alkanolsulfonic acid, or a mixture of both, and divalent tin salt and divalent lead salt. It has been discovered that a reflow solder plated material of excellent quality can be obtained by using a plating bath in which formalin is added in addition to the above-mentioned surfactant.

Therefore, an object of the present invention is to provide a method for advantageously producing a reflow solder plated material that is excellent in quality in terms of appearance, uniformity of plated film thickness, corrosion resistance, etc.

The present invention will be explained in detail below.

The feature of the present invention is that the following formula (
The method involves electroplating solder on a metal strip using a solder plating bath containing a surfactant made of a compound represented by I), and then subjecting the plated layer to a reflow treatment.

HO(C!H40), -(C3H60)b-(C!H4
0) c) l (I) (wherein 11.. is 2-35
0 and 1. In the present invention for reducing the amount of 11 to 66, the alkanesulfonic acid and alkanolsulfonic acid used as the free acid component of the plating bath have the following general formulas (VI) and (■), respectively.

R-3O3H (Vl) (In the formula, R represents an alkyl group having 1 to 12 carbon atoms) HO-R-5OsH (■) (In the formula, R represents an alkyl group having 1 to 12 carbon atoms, (The hydroxyl group may be bonded to any position of the alkyl group) The alkanesulfonic acids mentioned above include methanesulfonic acid,
Examples include ethanesulfonic acid, propanesulfonic acid, 2-propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, etc., and these can be used alone or in a mixture of two or more.

Examples of alkanolsulfonic acids include 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, and 2-hydroxypent-1-sulfonic acid. These may be used alone or in combination of two or more.

Furthermore, it can also be used as a mixture of two or more types of alkanesulfonic acids and alkanolsulfonic acids.

Tin salts and lead salts as solder plating components may be used in the form of the above-mentioned alkanesulfonic acid salts, alkanolsulfonic acid salts, and phenolsulfonic acid salts (or may be used as a mixture thereof). .

The concentration of tin ions and lead ions in the plating bath should be determined at a ratio depending on the desired plating film composition. Generally, when the plating film composition is Sn:Pb-9:1, the ion content in the plating bath is Since the ratio is also close to Sn":pb".=9:1, the above film composition of tin and lead and the ratio of ions in the bath have similar values.

The total ion concentration in the tin and lead plating bath is 5 to 10
0g/l, preferably 10 to 50g/l, but the metal ion concentration in the plating bath is 10g/j! If the current density is less than 50g/1, burnt occurs in the high current density area.
Even if it is made higher, the quality and electrodeposition speed will not be significantly improved, and on the contrary, the cost will increase due to pumping out the plating solution, so care must be taken.

In the present invention, the surfactant added to the above-mentioned matting bath is composed of a polyoxyethylene polyoxypropylene condensate having the formula (2), and the surfactant is
By adding it to the plating bath at a ratio of 30 g/l, preferably 1 to 15 g/10, the electrodeposited solder obtained from the bath will have a uniform matte to glossy appearance, and the quality after reflow treatment will be improved. will also be good. However, if the amount of surfactant added is less than 0.58/ffi, the so-called leveling effect will be low and the electrodeposited particles will become rough, making reflow processing difficult. On the other hand, if the amount exceeds 30 g/l, the effect of the amount added will be This is not economically advantageous as it will lead to saturation.

Further, in the present invention, the surfactant having the formula (1) 0.0
In addition to 5 to 20 g/It, the following formulas (II) to (V
) of one or more surfactants having a total of 0.
05~20g/j! When added in combination, the quality of reflow solder plating materials is further improved.

(In the formula, represents 5 to 15) Ethoxylate (α- or β-) Naphtholsulfonic acid, (In the formula, represents 5 to 30) Ethoxylate (α- or β-) naphthol, (in the formula, is 5 to 3
01. represents 1 to 10) of ethoxylate (α- or β-) naphthol with ethylene oxide.
Propylene oxide adduct, propylene oxide/ethylene oxide adduct.

Furthermore, in the present invention, the electrodeposition surface of solder plating is made dense,
In addition to the above surfactants, 0.1 to 2 kl/l of formalin is added to improve the plating quality after reflow processing.
It can also be added to plating baths. In this case, the amount of formalin added is 0, 1e+ II/j! If it is less than 20μl1, the effect of finer electrodeposited particles cannot be obtained;
If the amount exceeds 711, the above effect will be saturated, so it is uneconomical to add more than that.

In the present invention, solder is electroplated using various solder plating baths as described above, using a metal strip as a cathode, and then a reflow treatment is performed on the plating layer. Typical applications include light electrical parts such as terminals and connectors.

The base materials used for reflow solder plating materials include copper,
Examples include copper alloy, iron, iron alloy, etc., and reflow solder plating is performed to improve the quality of the surface of these base materials, such as corrosion resistance, solderability, and electrical connectivity.

Copper alloys used for the above base material include copper-zinc alloys such as brass and red copper, copper-tin alloys such as phosphor bronze, and copper-tin alloys.
Examples include nickel silver, which is a nickel-zinc alloy, and titanium copper, which is a copper-titanium alloy.

Further, as the iron alloy, various types of stainless steel copper, high nickel alloy, etc. can be used.

The base material for reflow solder plating materials is selected taking into consideration characteristics such as strength and conductivity, but in the present invention, the base material is Copper-based materials are better than iron-based materials. Therefore, even when an iron-based material is used as the base material, plating quality is improved by applying copper as an underplating to tin. Such an effect is due to the fact that tin in the solder plating layer applied according to the present invention forms a dense copper-tin intermetallic compound layer with the underlying copper component during reflow treatment.

In this case, the base layer only needs to have a copper component of 30% or more, and may be a base layer formed by other methods such as cladding.

Regarding the reflow treatment performed in the present invention, a method is known in which a solder plating layer is electrodeposited and then immersed in an aqueous solution containing various free acids, bases, or surfactants, and then the reflow treatment is performed. This method is usually carried out in a drag-out tank after solder plating, and is called flux treatment, which heats the solder plating layer to just above its melting point and suppresses the generation of SnO and SnO during the reflow process. It has the function of causing the electrodeposited solder particles to quickly melt and flow to form a smooth surface.

Therefore, in the present invention, the above-mentioned flux treatment was also used in the reflow treatment, and the following results were obtained.

That is, 1 to 100 g/l of alkanesulfonic acid or alkanolsulfonic acid or a mixture of both used as the free acid component of the electroplating bath, and a mixture of one or more surfactants added to the electroplating bath. 0.0
It was found that when an aqueous solution containing 1 to 10 g/ll as a flux was applied to the solder plating layer after electroplating and a reflow treatment was performed, the appearance and gloss became better, and the quality was also improved.

Further, according to the present invention, there is an advantage that the process can be performed effectively even under a wide range of current density, temperature conditions, and stirring conditions.

EXAMPLES The present invention and its effects will be specifically explained below using Examples. However, the tamping solution composition and plating working conditions shown in the examples are examples for specific explanation, and the present invention should not be limited to these, and can be arbitrarily changed in accordance with the above objectives. It should be understood that

Examples Various metal plates made of base materials having a thickness of 0.2 su + as shown in Table 1 were subjected to alkaline degreasing, electrolytic degreasing, pickling and neutralization treatment by conventional methods, and then solder plating was applied. However, S
Regarding O5304, in order to improve the adhesion of the plating, a wood bath (NiClt・6H, 0240 g/l
Strike plating was performed for 1 minute at a current density of 5 A/drrl using hydrochloric acid (containing 10 ml of hydrochloric acid).

In addition, as a base plating for solder, the treated copper is treated in a sulfuric acid bath (CuSO*・5Hz0250g/j!5kh
sO < 100 g/l).

Further, the reflow treatment of the solder plating layer was performed by holding the solder plated layer at a temperature of 700° C. for 5 to 10 seconds in an electric furnace (in the atmosphere).

Next, each of the reflow solder plated materials obtained by processing under each plating condition was evaluated based on the following criteria.

(2) Appearance was judged to be good if the plating showed good uniformity of gloss and no wetting defects occurred.

■Solderability was determined by aging the plated test piece for 1 hour (based on M 5TD-202E 208C) and then testing it for 60S.
The sample was immersed in an n/40Pb solder bath (230±5°C), and the time t until wetting was measured using the meniscograph method. T! It is determined that the shorter is, the better the solderability is.

■The salt water spray test was conducted in accordance with JIS Z 2371, and those that did not generate white rust after 5 hours of spraying were judged to be good.

As a comparative example, reflow solder plated materials obtained using copper as the base material and under the flashing conditions shown in Table 2 were evaluated in the same manner as above.

The results are shown in Tables 1 and 2, respectively.

As seen in the above tables, all of the plating materials obtained in the Examples of the present invention are superior in quality to those in the Comparative Examples.

In addition, l1hl and fish 4 and magnetic 5, magnetic 7 and 11h of the example
As can be seen from the comparison in Example 12, the quality of the solder plated material is better when copper or copper alloy is used as the base material than when iron-based. As can be seen from each comparison, the quality of solder plating is improved both when flux treatment is performed, and when a specific amount of formalin is added to the plating solution, as seen from the comparison between Arashi 1 and 1lh6 in the example. The improvement effect is recognized.

Claims (6)

[Claims] (1) A method for producing a reflow tin-lead alloy plated material by electroplating a tin-lead alloy on a metal strip and then subjecting the plated layer to a reflow treatment in which the plated layer is heated above its melting point and melted, As an electroplating bath, a compound represented by the following formula (I) is added to a solution containing a free acid component consisting of alkanesulfonic acid or alkanolsulfonic acid or a mixture of both, and divalent tin salt and divalent lead salt. A method for producing a reflow tin-lead alloy plating material, characterized by using a plating solution containing a surfactant. HO(C_2H_4O)_a-(C_3H_6O)_b
−(C_2H_4O)_cH(I) (in the formula, _a_+
__c is 2-350, __b is 11-66) (2) The electroplating bath contains 0.05 to 20 g/l of a surfactant represented by the above formula (I) and the following formulas (II) to (V
The manufacturing method according to claim (1), comprising a tacking solution containing one or more surfactants represented by 0.05 to 20 g/l in total. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, __n represents 5 to 15) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) (In the formula, __m represents 5 to 30) ▲Mathematical formula , chemical formulas, tables, etc. ▼(IV) (In the formula, _x represents 5 to 30, __y represents 1 to 10, respectively) ▲There are mathematical formulas, chemical formulas, tables, etc. ▼(V) (In the formula, _X represents 1 to 10 , _Y represents 5 to 30, respectively) (3) The manufacturing method according to claim 1 or 2, wherein the electroplating bath contains a tin salt that produces 10 to 50 g/l of stannous ions. (4) The electroplating bath comprises a plating solution to which 0.1 to 20 ml/l of formalin has been added.
) to (3). (5) The manufacturing method according to any one of claims (1) to (4), in which copper or a copper alloy is used as the tin plating base. (6) Alkanesulfonic acid or alkanolsulfonic acid, or a mixture of both, 0.05% of the tin-lead alloy plated layer after electroplating was used as the free acid component of the electroplating bath.
~50 g/l and 0.01 to 10 g of one or more surfactants used for addition to the electroplating bath
The manufacturing method according to any one of claims (1) to (5), wherein a reflow treatment is performed by applying an aqueous solution containing /l as a flux to the tin-lead alloy plating layer. .