JP2002241987A - Sn-Cu ALLOY PLATING BATH AND Sn-Cu ALLOY PLATING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Sn-Cu alloy plating bath which is a sulfuric acid bath consisting of sulfuric acid, a tin compound and a copper compound, and which enables the deposition of a dense Sn-Cu alloy plating film having good adhesion by electroplating. SOLUTION: The Sn-Cu alloy plating film enables the deposition of an Sn-Cu alloy plating film which does not substantially contain lead on the object to be plated by electroplating. The plating bath is compounded with sulfuric acid, a tin compound, a copper compound and an N,N-bis(polyoxyethylene)alkylamine compound shown by the formula: CnH2n+1[(CH2CH2O)mH]2 (wherein, n=10, to 20, and m=2 to 10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Sn-Cu alloy plating bath and a Sn-Cu alloy plating method, and more particularly, to a plating object containing substantially no lead on a plating object by electrolytic plating. Sn-Cu that can be formed
An object of the present invention is to provide an alloy plating bath and a Sn-Cu alloy plating method using the Sn-Cu alloy plating bath.

[0002]

2. Description of the Related Art In recent years, lead-free solder (hereinafter sometimes referred to as lead-free solder) has been rapidly developed from the viewpoint of environmental protection and the like. One of the candidates. When such a Sn—Cu alloy solder is used for mounting a semiconductor device or the like, a solder plating film made of a Sn—Cu alloy is formed on a mounting surface. However, when a solder plating film made of a Sn—Cu alloy is formed on a plating target by electrolytic plating, copper ions (Cu ²⁺ ) and tin ions (Sn
²⁺ ), it is necessary to substantially eliminate the potential difference between the two. For this reason, a complex is formed in the electrolytic plating bath with an additive capable of substantially eliminating the potential difference between them, specifically, copper ions such as alkanesulfonic acid, gluconic acid, citric acid, tartaric acid, sulfosuccinic acid, and pyrophosphoric acid. Possible additives have been added.

[0003]

As described above, Sn-Cu
By adding an additive capable of forming a complex with copper ions to an electrolytic plating bath for alloy plating, copper ions (Cu
²⁺ ) and a tin ion (Sn ²⁺ ) can be substantially eliminated. However, the drainage treatment of the plating bath that forms such a complex compound is difficult, and the cost of the additive is relatively high, so that the running cost of Sn—Cu alloy plating increases. On the other hand, a sulfuric acid bath composed of sulfuric acid, a tin compound, and a copper compound can perform a drainage treatment by a simple neutralization treatment, but cannot form a dense Sn—Cu alloy plating film having good adhesion by electrolytic plating. It cannot be put to practical use at all. Therefore, an object of the present invention is to provide a sulfuric acid bath composed of sulfuric acid, a tin compound and a copper compound, which is dense and has good adhesion by electrolytic plating.
An object of the present invention is to provide a Sn-Cu alloy plating bath and a Sn-Cu alloy plating method capable of forming a u-alloy plating film.

[0004]

Means for Solving the Problems The present inventors have studied to solve the above problems, and as a result, N, N-bis (polyoxyethylene) was added to a sulfuric acid bath composed of sulfuric acid, a tin compound and a copper compound.
It has been found that by adding an alkylamine compound, the potential difference between copper ions (Cu ²⁺ ) and tin ions (Sn ²⁺ ) can be substantially eliminated, and the present invention has been achieved. That is, according to the present invention, the plating object contains substantially no lead.
In a Sn-Cu alloy plating bath capable of forming an n-Cu alloy plating film by electrolytic plating, the plating bath includes:
Sulfuric acid, tin compounds, copper compounds and N, N-
An Sn-Cu alloy plating bath characterized in that a bis (polyoxyethylene) alkylamine compound is blended. Further, the present invention, when forming a Sn-Cu alloy plating film containing substantially no lead on the plating object by electrolytic plating, as a plating bath for performing the electrolytic plating,
Sulfuric acid, tin compounds, copper compounds and N, N-
Sn- characterized by using a plating bath containing a bis (polyoxyethylene) alkylamine compound.
This is a plating method of Cu alloy plating.

Embedded image

In the present invention, C ₁₈ H _{37 is} used as the N, N-bis (polyoxyethylene) alkylamine compound.
N [(CH ₂ CH ₂ O) ₄ H] ₂ or C ₁₈ H ₃₇ N [(CH ₂
CH ₂ O) ₁₀ H] ₂ can be suitably used. Also,
As a plating bath, the copper content of the plating film obtained is 1.
By using a plating bath adjusted to be 3 to 9.3 atomic%, a plating film made of a Sn-Cu eutectic alloy can be obtained, which can be suitably used as a lead-free solder plating. . Further, when the electrolytic plating is performed, by setting the current density to 1 A / dm ² or more, a dense Sn—Cu alloy plating film having good adhesion can be easily formed.

In a sulfuric acid bath composed of sulfuric acid, a tin compound and a copper compound, the reduction potential of copper ions (Cu ²⁺ ) is around 0.0 V, and the reduction potential of tin ions (Sn ²⁺ ) is -0.45.
It exists near V. In this regard, in the plating bath according to the present invention, by adding an N, N-bis (polyoxyethylene) alkylamine compound to the sulfuric acid bath,-
Without suppressing the reduction current of tin ions (Sn ²⁺ ) in the vicinity of 0.45 V, 0.0-V of copper ions (Cu ²⁺ )
The reduction current in the vicinity of 0.4 V could be suppressed. As a result, in a sulfuric acid bath, the potential difference between copper ions (Cu ²⁺ ) and tin ions (Sn ²⁺ ) can be substantially eliminated, and a Sn—Cu alloy plating film can be formed on a plating target by electrolytic plating.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a plating bath for electrolytic plating contains a sulfuric acid, a tin compound, a copper compound and an N, N-bis (polyoxyethylene) alkylamine compound shown in the following [Chemical Formula 4]. It is important to use a suitable plating bath.

Embedded image As the tin compound and the copper compound to be mixed in the plating bath, a sulfate can be suitably used.
mention may be made of nSO ₄ and CuSO _4. Also, N,
Examples of the N-bis (polyoxyethylene) alkylamine compound include C ₁₈ H ₃₇ N [(CH ₂ CH ₂ O) ₄ H] _{2 and} C ₁₈
H ₃₇ N [(CH ₂ CH ₂ O) ₁₀ H] ₂ can be suitably used.

Regarding the behavior of the N, N-bis (polyoxyethylene) alkylamine compound in a plating bath, first, an electrocapillary curve obtained in a 2 mol sulfuric acid solution using a polarographic apparatus is shown in FIG. . In FIG. 1, the horizontal axis represents the potential, and the vertical axis represents the amount of mercury dropped. Further, in FIG. 1, curve 1 in figure levels only 2 moles of sulfuric acid solution, the curve 2 is 2 moles of the sulfuric acid solution C ₁₈ H ₃₇ N [(C
The level at which 1 mmol of H ₂ CH ₂ O) ₄ H] ₂ (hereinafter sometimes referred to as POOA-4) was added. Curve 3 shows C ₁₈ H ₃₇ N [(CH ₂ CH ₂ ) in a 2 mol sulfuric acid solution. O) ₁₀ H]
₂ shows an electrocapillary curve at a level of 1 mmol (hereinafter sometimes referred to as POOA-10). As is apparent from FIG. 1, mercury was dropped in the negative potential region at the level to which POOA-4 and POOA-10 were added (curves 2 and 3) as compared to the level of sulfuric acid solution alone (curve 1). The amount was significantly reduced, and POOA-4 and POOA-1
It can be seen that 0 is adsorbed on the electrode.

As described above, in the negative potential region, copper ions (Cu ²⁺ ) and tin ions (Sn) in the plating solution to which POOA-4 or POOA-10 adsorbed on the electrode are added.
FIG. 2 shows the results of measuring the reduction potential of ²⁺ ) using a polarographic apparatus. In FIG. 2, the horizontal axis indicates the potential, and the vertical axis indicates the current value. In FIG. 2, the reference sulfuric acid bath [H ₂ SO ₄ (2 mol) + CuSO ₄ (5 mmol)]
+ SnSO ₄ (5 mmol)] (curve 10), target sulfuric acid bath [reference sulfuric acid bath + POOA-4 (1 mmol)] (curve 12), target sulfuric acid bath [reference sulfuric acid bath + POOA-10 (1)
(Millimol)] (curve 14) shows the respective reduction potentials of Cu ²⁺ and Sn ²⁺ . Among the plating solutions shown in FIG.
-4 or POOA-10 without reference sulfuric acid bath (curve 1)
0), the copper ion (Cu ²⁺ ) exhibits a one-step reduction wave having a half-wave potential near 0.0 V, and the tin ion (Sn ²⁺ )
A single-stage reduction wave having a half-wave potential near −0.45 V is exhibited. On the other hand, POOA-4 or POO was added to the standard sulfuric acid bath.
In the target sulfuric acid bath to which A-10 was added (curves 12 and 14), the reduction current of copper ions (Cu ²⁺ ) in the range of 0.0V to -0.4V was suppressed, and the negative current was lower than -0.4V. , The current value gradually increases based on the reduction of copper ions (Cu ²⁺ ) and tin ions (Sn ²⁺ ). This phenomenon is apparent from the electrocapillary curve shown in FIG.
4 or POOA-10 is adsorbed and has a strong inhibitory effect on the reduction of copper ions (Cu ²⁺ ), but tin ions (Sn
²⁺ ) does not show a significant inhibitory effect on the reduction. In addition, from the comparison between the curves 12 and 14 shown in FIG. 2, copper ions (Cu ²⁺ ) and tin ions (Sn ²⁺ )
Is more effective in reducing POO than POOA-4.
A-10 is large.

The above-described electrocapillary curve shown in FIG. 1 and the polarogram shown in FIG. 2 are obtained by examining a diluted solution. Therefore, the cathode polarization curve in a practical plating bath is measured using an automatic polarizer. FIG. 3 shows the measurement results. In measuring the cathode polarization curve, a pure copper plate having a surface area of 1 cm ² was used for the cathode, and a platinum winding was used for the anode. In FIG. 3, the horizontal axis indicates the potential, and the vertical axis (log scale) indicates the current value. In FIG. 3, the reference sulfuric acid bath [H ₂ SO ₄ (2 mol) + CuSO ₄ (0.008)
Mol) + SnSO ₄ (0.2 mol)] (curve 20), target sulfuric acid bath [reference sulfuric acid bath + POOA-4 (1 mmol)]
(Curve 22), target sulfuric acid bath [reference sulfuric acid bath + POOA-1]
0 (1 mmol)] (curve 24). Among the sulfuric acid baths shown in FIG. 3, in the standard sulfuric acid bath to which POOA-4 or POOA-10 is not added (curve 20), a current based on the reduction of copper ions (Cu ²⁺ ) flows from around 0.0V, One-stage limit current (5 × 10 ⁻² A / dm ² ) in a potential range of −0.2 V to −0.45 V
Is shown. Further, from the vicinity of -0.45 V, tin ions (S
The current value based on the reduction of n ²⁺ ) sharply increases. on the other hand,
In the target sulfuric acid bath (curves 22 and 24) in which POOA-4 or POOA-10 was added to the basic sulfuric acid bath, reduction of copper ions (Cu ²⁺ ) from around 0.0 V was suppressed, and the current density was 2 A / dm. ^{In the} vicinity of ² , from -0.45V to -1.0
Over a wide potential range of V, there is a one-step limiting current mainly due to the reduction of tin ions (Sn ²⁺ ). This limiting current is a phenomenon in which the diffusion process of tin ions (Sn ²⁺ ) through the adsorption layer of POOA-4 or POOA-10 is rate-limiting. In the curves 22 and 24 shown in FIG. 3, the current value increases from around the potential −1.0 V, but is based on the reduction of hydrogen ions.

The target sulfuric acid bath shown in FIG.
By using (24), an Sn—Cu alloy plating film can be formed by performing electrolytic plating at a current density of 5 × 10 ⁻² A / dm ² or more, which is the limit current of copper ions (Cu ²⁺ ). This means that the current density was 2 A / dm ^{2 in} each of the sulfuric acid baths (curves 20, 22, and 24) shown in FIG.
X-ray diffraction was performed on each of the plating films formed by subjecting the plating target to electrolytic plating and the results are shown in FIG. In the plating film formed using the basic sulfuric acid bath (curve 20), the relatively strong (200) surface and the (10)
1) Diffraction lines based on the plane were observed. On the other hand, in the target sulfuric acid bath in which POOA-4 or POOA-10 was added to the basic sulfuric acid bath (curves 22 and 24), the diffraction line intensity of the (200) plane of the formed plating film was increased. (1
The diffraction line intensity of the 01) plane decreased. Although not shown in FIG. 4, the X-ray diffraction of the plating film formed by performing the electrolytic plating at a low current density so that the copper content becomes relatively large, although the strength is weak, the intermetallic compound A diffraction line of Cu ₆ Sn ₅ based on (η phase) was also observed. From the results of the X-ray diffraction, the plating film formed using the target sulfuric acid bath (curves 22 and 24) is a Sn-Cu alloy and has a β-
It is presumed to be a eutectic structure of Sn phase and η phase (Cu ₆ Sn _5).

As shown in FIGS. 2 and 3, sulfuric acid and tin compound
Product, a basic sulfuric acid bath composed of a copper compound, POOA-4 or
By adding POOA-10, copper ions (C
u²⁺) Suppresses the reduction current in the vicinity of -0.4V from 0.0V
And copper ions (Cu²⁺) And tin ions (Sn²⁺) And potential
Substantially eliminates the difference and can be plated by electrolytic plating
An Sn—Cu alloy plating film can be formed on the object. Like this
Copper content in Sn-Cu alloy plating film formed by
The current density in electrolytic plating and copper ion in sulfuric acid bath
(Cu²⁺) The effect of the amount was examined, and the results are shown in FIG.
You. In FIG. 5, the horizontal axis represents the current density of electrolytic plating.
The vertical axis shows the copper content in the Sn-Cu alloy plating film.
You. In FIG. 5, a curve 30 in the figure indicates that the sulfuric acid bath composition is [H_Two
SO_Four(2 mol) + CuSO_Four(0.008 mol) + Sn
SO_Four(0.2 mol) + POOA-10 (1 mmol)
Curve 32 shows the sulfuric acid bath composition.
Is [H_TwoSO_Four(2 mol) + CuSO_Four(0.016 m
+) SnSO_Four(0.2 mol) + POOA-10 (1
Mmol)]. Curve 30, FIG.
32, the current density is 0.5 A / dm.^Two
When the copper content in the plating film is maximized and the current
Density is 1.0 A / dm^TwoAbove, the copper content in the plating film
Although the amount increased slightly, the Sn-
A Cu alloy plating film can be obtained. Such current density
The upper limit of the degree is 7 A / dm ^TwoIt is preferable that Also,
Copper content in sulfuric acid bath with plating film of curve 30
Corresponds to 3.8 at% (hereinafter sometimes referred to as at%).
The content of copper in the formed plating film depends on the current density
Is 1A / dm^TwoAbove is 2.8 to 3.7 at%. Ma
In addition, copper contained in the sulfuric acid bath on which the plating film of curve 32 was formed.
The content is 7.4at%, compared to the copper in the formed plating film.
The current density is 1 A / dm^TwoAbove is 5.8 ~
It was 6.9 at%. From this result, POOA-10 was added.
In the added sulfuric acid bath, the current density is 1.0 A / dm.^Twomore than
The copper content is approximately proportional to the copper concentration in the sulfuric acid bath.
Stably obtains Sn-Cu alloy plating film of almost constant composition
Can be Here, instead of POOA-10, PO
Plating formed by sulfuric acid bath with OA-4 added
When the content of copper in the film was measured,
The copper content was 3.2-6.0 at%. Against this
And a sulfuric acid bath to which the same amount of POOA-10 was added.
Therefore, the content of copper in the formed plating film was measured.
However, the content of copper in the plating film is 2.8 to 5.3a.
formed by a sulfuric acid bath with t% and POOA-4
Less than the copper content in the plating film. This is a copper
ON (Cu²⁺) Is POOA-4
Presumed to be due to POOA-10 being larger than
It is.

FIG. 6 shows the results of measuring the melting point of a Sn—Cu alloy plating film formed by electrolytic plating using a sulfuric acid bath to which POOA-10 was added using a differential scanning calorimeter (DSC). Show. A curve 40 shown in FIG. 6 represents a Sn—Cu alloy formed by a casting method and having a copper content of 1.3 at%.
It is a DSC curve of a eutectic alloy. Also, curves 42 and 44
Is a Sn—Cu alloy plating film formed by electrolytic plating using a sulfuric acid bath to which POOA-10 (1 mmol) is added, in which the content of copper ions (Cu ²⁺ ) in the sulfuric acid bath is changed. Curve of the Sn-Cu alloy plating film having a copper content of 3.2 at% (curve 42) and the DSC curve of the Sn-Cu alloy plating film having a copper content of 9.3 at% (curve 44) It is. Both curves 42 and 44 show Sn—C formed by casting and having a copper content of 1.3 at%.
Since the u-eutectic alloy is melted in the vicinity of the melting point of 227 ° C, it has the same melting characteristics as the Sn-Cu eutectic alloy. As described above, by using a plating bath containing sulfuric acid, a tin compound, a copper compound and an N, N-bis (polyoxyethylene) alkylamine compound as a plating bath for performing electrolytic plating, By plating, a dense Sn—Cu alloy plating film having good adhesion can be formed, and can be used as a lead-free solder plating. Therefore, a lead-free solder plating film made of a Sn—Cu alloy can be easily formed on a mounting surface of a semiconductor device or the like. Furthermore, since no complex compound or the like is added, it can be discarded by simple drainage treatment such as neutralization treatment, and the running cost of Sn-Cu alloy plating can be reduced.

[0014]

The present invention will be described in more detail with reference to the following examples. Reference Example As a plating bath, H ₂ SO ₄ (2 mol), CuSO
₄ (0.008 mol) and a plating bath to which SnSO ₄ (0.2 mol) was added. Electroplating was performed on such a plating bath using a test piece made of low-carbon steel (SPCCS) as a plating object as a cathode and a platinum winding as an anode. In this electrolytic plating, the bath temperature was adjusted to 25 ± 1 ° C. without stirring and the current density was adjusted to 1 A / dm ^2, and plating was performed to form a plating film. Further, similarly, the current density is 2 A / dm ² , 3 A
/ Dm ^2, and electroplating them respectively.
Plating films corresponding to each current density were formed. Next, electron micrographs (magnification: 500 times) of the surface of the plating film obtained by performing electrolytic plating while changing the current density were taken. FIG. 7 is a mimic diagram of this micrograph.
(A) to (c) are shown. FIG. 7A shows that the current density is 1A.
/ Dm ² to indicate the status of adjustment to form the plating film surface, FIG. 7 (b) shows the state of the plating film surface formed by adjusting the current density 2A / dm ^2. FIG.
(C) shows the state of the plating film surface formed by adjusting the current density to 3 A / dm ² . FIG.
In the plating film shown in (c), large massive crystals grown in the current direction are formed, and the current density is 3 A / dm.
^In the plating film [FIG. 7 (c)] formed by adjusting to ² ,
Dendritic crystals are formed.

Example 1 As a plating bath, H ₂ SO ₄ (2 mol), CuSO
₄ (0.008 mol), SnSO ₄ (0.2 mol) and P
A plating bath to which OOA-4 (1 mmol) was added was prepared. Here, POOA-4 is C ₁₈ H ₃₇ N [(CH
₂ CH ₂ O) ₄ H] ₂ . The plating bath was subjected to electrolytic plating using a low-carbon steel plate (SPCCS) as a plating target as a cathode and a platinum winding as an anode. During this electrolytic plating, the bath temperature was adjusted to 25 ± 1 ° C. without stirring,
The plating was performed by adjusting the current density to be 1 A / dm ² to form a plating film. Further, similarly, the current density was formed respectively plating film is subjected to adjustment to electroless plating so as to ^{2A / dm 2, 3A / dm} 2. Next, electron micrographs (magnification: 500 times) of the surface of the plating film obtained by performing electrolytic plating while changing the current density were taken. FIG. 8 shows a mimic diagram of this electron micrograph.
(A) to (c) are shown. FIG. 8A shows that the current density is 1A.
/ Dm ² to indicate the status of adjustment to form the plating film surface, FIG. 8 (b) shows the state of the plating film surface formed by adjusting the current density 2A / dm ^2. FIG.
(C) shows the state of the plating film surface formed by adjusting the current density to 3 A / dm ² . As is clear from FIGS. 8A to 8C, unlike the plating film of the reference example, the formed plating film does not have dendritic crystals and has small-diameter granular or block-like crystals. Are uniformly deposited on the entire surface, and a dense plating film is formed.

Example 2 In Example 1, POOA-1 was used instead of POOA-4.
A plating film was formed in the same manner as in Example 1 except that 0 was used. Here, POOA-10 is C ₁₈ H ₃₇ N [(C
H ₂ CH ₂ O) ₁₀ H] ₂ . Next, in the same manner as in Example 1, an electron micrograph (magnification: 500 times) of each surface of the obtained plating film was taken. FIGS. 9 (a) to 9 (c) show mimic views of the electron micrographs. FIG.
9A shows the state of the surface of the plating film formed by adjusting the current density to 1 A / dm ² , and FIG. 9B shows the state of the surface of the plating film formed by adjusting the current density to 2 A / dm ² . Indicates the status. FIG. 9C shows that the current density is 3 A / dm.
² shows the state of the surface of the plating film formed by adjustment. As is clear from FIGS. 9A to 9C, unlike the plating film of the reference example, the formed plating film has no small-diameter granular or block-like crystals without dendritic crystals. Are uniformly deposited on the entire surface, and a dense plating film is formed. Further, in the plating films shown in FIGS. 9A to 9C, the crystal grains are finer than in the plating films of Example 1 shown in FIGS. 8A to 8C.

Example 3 A plating film was obtained in the same manner as in Example 2 except that the current density was changed from 0.2 to 7 A / dm ² . When the content of copper in the obtained plating film was measured by an atomic absorption spectrophotometer, the content of copper in the plating film was 2.
It was 8 to 9.3 at%. As a result of measuring this plating film using a differential scanning calorimeter (DSC), it melted at around 227 ° C. as in the case of the Sn—Cu eutectic alloy.

Example 4 As a plating bath, H ₂ SO ₄ (2 mol), CuSO ₄ , S
A plating bath to which nSO ₄ (0.2 mol) and POOA-10 (1 mmol) was added was prepared. Electroplating was performed on such a plating bath using a test piece made of low-carbon steel (SPCCS) as a plating object as a cathode and a platinum winding as an anode. The current density at this time is 2 A / dm
² and adjust the blending amount of CuSO ₄ to 0.004 to 0.01.
It varied between 6 moles. The copper content in the obtained plating film was 1.6 to 5.8 at%. The solder wettability of the test piece on which the plating film was formed was measured by a meniscograph method. In the meniscograph method, Sn—Ag (3.5 wt%) — Cu is used as solder.
(0.7 wt%) solder, a test piece coated with a flux [rosin (25%)-diethylamine hydrochloride (0.5%)] in a solder bath maintained at 250 ° C. was immersed at a speed of 2 mm. / Sec, the immersion depth was 2 mm, and the immersion time was 10 seconds, and the solder wetting time was measured.
The wetting time of this test piece was 2.4 sec regardless of the copper content in the plating film. On the other hand, as a plating bath, a plating bath for Sn plating to which H ₂ SO ₄ (2 mol), SnSO ₄ (0.2 mol) and POOA-10 (1 mmol) were added was prepared, and the test piece was subjected to electrolytic plating. An Sn plating film was formed on the surface. When the solder wettability of the test piece on which the Sn plating film was formed was measured in the same manner, it was 2.54 sec. The solder wettability of a test piece having a Sn—Cu alloy plating film formed by electrolytic plating using a commercially available plating solution for Sn—Cu alloy plating was measured to be 2.66 sec. . As described above, the Sn—Cu alloy plating film formed by electrolytic plating using the sulfuric acid bath to which POOA-10 was added had good solder wettability.

[0019]

According to the present invention, a dense Sn--Cu alloy plating film having good adhesion can be formed by electrolytic plating, and can be used as a lead-free solder plating. Therefore, a lead-free solder plating film made of a Sn—Cu alloy can be easily formed on a mounting surface of a semiconductor device or the like. Furthermore, since the plating bath does not contain a complex compound or the like,
The drainage treatment of the plating bath can be dealt with by simple drainage treatment such as neutralization treatment, and the running cost of Sn-Cu alloy plating can be reduced.

[Brief description of the drawings]

FIG. 1 is a graph of an electrocapillary curve illustrating the behavior of an N, N-bis (polyoxyethylene) alkylamine compound in a sulfuric acid solution.

[Figure 2] was measured using a polarographic device, a graph of the reduction potential of the copper ions in the plating solution (Cu ²⁺⁾ and tin ions (Sn ^2+).

FIG. 3 is a graph showing a cathode polarization curve in a practical plating bath.

FIG. 4 is an X-ray diffraction diagram of the plating film obtained.

FIG. 5 is a graph showing the relationship between the content of copper in the obtained plating film and the current density.

FIG. 6 is a graph showing the results of measuring the thermal characteristics of the obtained plating film using a differential scanning calorimeter (DSC).

FIG. 7 is a simulated view of an electron micrograph of the surface of a plating film obtained in a reference example.

FIG. 8 is a simulated view of an electron micrograph of the surface of the plating film obtained in Example 1.

9 is a simulated view of an electron micrograph of the surface of the plating film obtained in Example 2. FIG.

[Explanation of symbols]

12 Level of only 2 mol of sulfuric acid solution 2 Level of 1 mmol of POOA-4 added to 22 mol of sulfuric acid solution 3 Level of 1 mmol of POOA-10 added to 22 mol of sulfuric acid solution 10, 20 Standard sulfuric acid bath [ H ₂ SO ₄ + CuSO ₄ + Sn
SO ₄ ] 12,22 Target sulfuric acid bath [Standard sulfuric acid bath + POOA-4] 14,24,30,32 Target sulfuric acid bath [Standard sulfuric acid bath + P
OOA-10] 40 Sn-Cu eutectic alloy formed by casting method 42, 44 Sulfuric acid bath [Standard sulfuric acid bath + POOA-1]
0]

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shinichi Wakabayashi 711, Rita, Kurita-sha, Nagano-shi, Nagano F-term in Shinko Electric Industries Co., Ltd. 4K023 AB34 BA06 CA01 CB13 CB33 DA06 DA07 DA08

Claims (7)

[Claims] 1. An object to be plated that does not substantially contain lead.
In an Sn-Cu alloy plating bath capable of forming an n-Cu alloy plating film by electrolytic plating, the plating bath includes sulfuric acid, a tin compound, a copper compound, and N, N-bis (polyoxyethylene) shown in the following [Chemical Formula 1]. A) an alkylamine compound,
-Cu alloy plating bath. Embedded image 2. N, N-bis (polyoxyethylene) alkyl
Luamine compound is C₁₈H₃₇N [(CH_TwoCH_TwoO)
_FourH]_TwoOr C₁₈H₃₇N [(CH_TwoCH_TwoO)_TenH] _TwoIn
The Sn-Cu alloy plating bath according to claim 1. 3. The Sn according to claim 1, wherein the copper content in the plating bath is adjusted so that the copper content of the obtained plating film is 1.3 to 9.3 atomic%. -Cu
Alloy plating bath. 4. An S-plating object which does not substantially contain lead.
When an n-Cu alloy plating film is formed by electrolytic plating, sulfuric acid, tin compound,
An Sn-Cu alloy plating method characterized by using a plating bath containing a copper compound and an N, N-bis (polyoxyethylene) alkylamine compound shown in the following [Chemical Formula 2]. Embedded image 5. An N, N-bis (polyoxyethylene) alkylamine compound comprising C ₁₈ H ₃₇ N [(CH ₂ CH ₂ O)
₄ H] ₂ or _{C 18 H 37 N [(CH} 2 CH 2 O) 10 H] Sn-Cu alloy plating method as claimed in claim 4, wherein the use of _2. 6. The plating bath according to claim 4, wherein the plating bath is a plating bath adjusted so that the copper content of the plating film obtained is 1.3 to 9.3 atomic%.
n-Cu alloy plating method. 7. The method according to claim 1, wherein the current density is 1 A when performing the electrolytic plating.
/ Dm ² or more and Sn-Cu alloy plating method of any one of claims 4 to 6.