JPH07249445A - Tin or tin alloy plating material for terminal connector of electronic device, electric parts, etc., with superior surface contact resistance characteristics and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain superior surface contact resistance characteristics by setting a specific value for the peak area ratio of PC (2p)/Sn (3d) of a plating surface obtained by X-ray photoelectric spectroscopy in a plating surface formed by applying tin or tin alloy plating on a copper or copper alloy. CONSTITUTION:Tin or tin alloy plating is applied on copper or copper alloy. The plating surface of the tin or tin alloy plating material is formed so that the peak area ratio of P (2p)/Sn (3d) on the tin or tin alloy plating surface obtained by X-ray photoelectric spectroscopy may be 0.03 to 0.05. If the peak area ratio is less than 0.003, the film is incomplete and oxydation of Sn may probably advance. On the other hand, if it exceeds 0.05, the film becomes thicker, and the contact resistance value on the plated surface may probably increase. The peak area of P (2p)/Sn (3d) can be controlled according to a electrolyzing time. When the electrolyzing time is longer or shorter, the peak area ratio of P (2p)/Sn (3d) is increased or decreased, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tin or tin alloy plating material for terminals and connectors of electronic devices, electric parts and the like and a method for producing the same, and in particular tin or tin alloy for terminals and connectors having excellent surface contact resistance characteristics. The present invention relates to a plated material and its manufacturing method.

[0002]

2. Description of the Related Art Generally, tin or a tin alloy-plated copper material or copper alloy material obtained by plating copper or a copper alloy with tin or a tin alloy is widely used as a material for terminals and connectors of electronic devices, electric parts and the like. ing. In recent years, the soldering method for electronic parts is a surface mount type (SMT;
Mount Technology).

The loading mounting type is a method in which lead wires of an electronic component are inserted into holes of a printed board and then soldered. On the other hand, the surface mount type is a method of soldering an electronic component to the surface of a printed circuit board. The surface mounting type soldering is a reflow method in which an appropriate amount of solder is supplied in advance to a joint between a component and a substrate, the component is placed and then the solder is melted, and soldering is performed. As a heating method used for reflow soldering, there are an infrared ray, latent heat of vaporization, a hot air circulation method, an overall heating method such as a hot plate, and a local heating method such as a heating tool, a light beam, a laser, and an air heater.

[0004]

The total heating method is excellent in productivity because the electronic components mounted on the substrate can be soldered together, but the unnecessary portions are also affected by heat. As a result, the tin or tin alloy plating surface of the contactor portion of the terminal / connector may be oxidized to increase the contact resistance value. As a countermeasure, the atmosphere in the heating furnace may be an N ₂ atmosphere or a reducing atmosphere such as H ₂ or CO, but this leads to an increase in cost.

On the other hand, the local heating method has an advantage of being able to selectively heat only a necessary portion, but has a problem of low productivity. It is considered that the total heating method with high productivity will increase in the future, but the conventional tin-plated material has a problem of surface oxidation.

[0006] As a technique for preventing the oxidation of the tin-plated surface, a method of electrolytically treating a tin-plated steel in a sodium dichromate solution after plating is widely used. When this treatment is performed, a hydrated oxide of Cr ³⁺ is formed on the tin-plated surface, and the oxidation of tin is suppressed. But,
This technique cannot be applied to tin-plated products for electronic parts because the hydrated oxide of Cr ³⁺ on tin-plating has a bad influence on the contact resistance. In addition, there is a problem of wastewater treatment containing harmful hexavalent chromium generated at this time. As described above, with the progress of SMT in electronic components, there has been a demand for the development of a tin or tin alloy plated material with less deterioration in contact resistance due to the oxidation of the tin or tin alloy plated surface. An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a tin or tin alloy plated material for terminals and connectors of electronic devices, electric parts, etc., which are excellent in surface contact resistance characteristics, and a method for producing the same. There is.

[0007]

In order to achieve the above object, the inventors of the present invention have conducted extensive research and as a result, as a result, P (2p) on the surface of a tin or tin alloy plated material obtained by X-ray photoelectron spectroscopy The inventors have found that the peak area ratio of / Sn (3d) is closely related, and completed the present invention.
That is, the present invention based on the above findings is based on the fact that the tin or tin alloy plating obtained by X-ray photoelectron spectroscopy is applied on the plating surface of a tin or tin alloy plating material obtained by plating tin or tin alloy on copper or copper alloy. Surface P (2p) / Sn
An electronic device having excellent surface contact resistance characteristics, wherein the peak area ratio of (3d) is 0.003 to 0.05,
The main point is tin or tin alloy plated materials for terminals and connectors of electric parts. Further, the present invention provides that after copper or a copper alloy is plated with tin or a tin alloy, at least one phosphoric acid ester having an aromatic substituent or phosphorous acid ester having an aromatic substituent is used, and a water-soluble organic compound. The gist is a method for producing a tin or tin alloy plated material for terminals and connectors of electronic devices, electric parts and the like, which is characterized by immersing in a treatment liquid containing a solvent and subjecting it to anodic electrolysis.

According to the present invention, the treatment liquid further comprises 0.1 to 10 wt% of phosphoric acid ester having an aromatic substituent or 0.1 to 10 wt% of phosphorous acid ester having an aromatic substituent.
%, And an aqueous solution containing 5 to 50 wt% of a water-soluble organic solvent is preferable, and the anodic electrolysis is performed at a voltage of 2 to 20.
V, electrolysis time is preferably 1 to 60 seconds.

[0009]

The structure and operation of the present invention will be described. In the present invention, a tin or tin alloy plated material is immersed in a treatment liquid containing at least one kind of phosphoric acid ester having an aromatic substituent or phosphorous acid ester having an aromatic substituent and a water-soluble organic solvent. By anodic electrolysis, a compound film of tin and an organic substance composed of the phosphoric acid ester or phosphorous acid ester or a mixture thereof is formed on the surface of the tin or tin alloy plating. The tin or tin alloy plated material that has been subjected to this treatment has its plated surface shielded from O ₂ and H ₂ O in the air, so that it is difficult to oxidize and the contact resistance does not deteriorate.
Since the coating film made of the phosphoric acid ester or phosphorous acid ester or the compound of tin and tin is thin, it does not adversely affect the contact resistance.

The components of the antioxidant treatment liquid must contain at least one kind of phosphoric acid ester having an aromatic substituent or phosphorous acid ester having an aromatic substituent and a water-soluble organic solvent. The concentration of the phosphoric acid ester or phosphorous acid ester contained in the antioxidant treatment liquid is preferably 0.1 to 10 wt%. If it is less than 0.1 wt%, the antioxidant effect is small, and if it exceeds 10 wt%, the antioxidant effect is not improved and it is economically wasteful.

The water-soluble organic solvent has an effect of easily dissolving the phosphoric acid ester or phosphite ester, which is hardly soluble in water, in water, and improves wettability between the antioxidant treatment liquid and the tin or tin alloy plating surface. effective. The concentration of the water-soluble organic solvent is preferably 5 to 50 wt%. If it is less than 5 wt%, the above effect is small, and if it exceeds 50 wt%, the effect is not improved due to the increase in concentration, which is economically wasteful. As the water-soluble organic solvent, ethanol, propanol or the like is preferable.

The tin or tin alloy plated surface of the present invention is X
P on the surface of plated material obtained by line photoelectron spectroscopy
The peak area ratio of (2p) / Sn (3d) is 0.003 to
Must be 0.05. What is X-ray photoelectron spectroscopy?
This is a method for elemental analysis by irradiating a solid surface with X-rays and measuring the kinetic energy of photoelectrons emitted by the photoelectric effect. From the obtained peak area ratio,
The composition ratio of P and Sn can be obtained.

The peak area ratio due to the 2p electron of P and the peak area due to the 3d electron of Sn must be 0.003 to 0.05. If the peak area ratio is less than 0.003, the film is incomplete and Sn oxidation may proceed. On the other hand, if it exceeds 0.05, the coating becomes thick and the contact resistance value of the plating surface may increase. The above P (2p) / S
The peak area ratio of n (3d) can be controlled by the electrolysis time. If the electrolysis time is long, P (2
The peak area ratio of p) / Sn (3d) increases and the area ratio decreases as the electrolysis time decreases.

The conditions for anodic electrolysis are preferably a voltage of 2 to 10 V and an electrolysis time of 1 to 60 seconds. Voltage less than 2V, electrolysis time 1
If it is less than a second, tin and the compound of phosphoric acid ester or phosphorous acid ester do not form a uniform film, and the antioxidant effect is small. On the other hand, when the voltage exceeds 10 V and the electrolysis time exceeds 60 seconds, the coating becomes too thick, which may adversely affect the contact resistance and the like. In addition, the reaction of tin with phosphoric acid ester or phosphorous acid ester is slow, and it takes a long time to form a film sufficient for antioxidation, by simply immersing in an antioxidation treatment liquid without performing anodic electrolysis. To do.

Examples of the phosphoric acid ester having an aromatic substituent include PO (OR) ₂ OH, PO (OR) (O
H) ₂ , PO (OR) ₃ (provided that at least one of R is an aromatic substituent) and diphenyl phosphate and the like are used. Examples of the phosphite having an aromatic substituent include the general formulas PO (OR) ₂ H, P (OH) (OR)
₂ , diphenyl phosphite represented by PO (OR) (OH) H (provided that at least one of R is an aromatic substituent) is used. If it does not have a phenyl group as a hydrophobic group, the antioxidant effect cannot be obtained. Therefore, it must have at least one aromatic substituent as a hydrophobic group.

The antioxidation technology of the present invention is an electro-bright tin or tin alloy plating material using a brightening agent, reflow tin or tin alloy plating material which is subjected to melting treatment after tin or tin alloy plating, and molten tin or tin alloy. The present invention is effective for any plated material, such as a molten tin or tin alloy plated material in which a material is passed through and plated, and an evaporated tin or tin alloy plated material plated by vapor deposition plating of a dry plating method. The tin alloy plated material is a copper alloy material plated with tin alloy containing at least one of Pb, In, Zn, Sb, Cd and Ag. As described above, according to the present invention, the tin or tin alloy plated surface is less likely to be oxidized, and the contact resistance is less likely to deteriorate with time, and the tin or tin alloy plated material for terminals and connectors of electronic devices, electric parts, etc. and its production. The method was established.

[0017]

EXAMPLES Examples of the present invention will be described, but the present invention is not limited thereto. The samples used in the examples are shown in [Table 1].

[0018]

[Table 1]

After the tin-plated material shown in [Table 1] was subjected to an antioxidant treatment under each condition, it was subjected to thermal aging under the conditions shown in [Table 2],
The change with time of the contact resistance value was measured under the conditions shown in [Table 3].

[0020]

[Table 2]

[0021]

[Table 3]

A tin-plated material having a P (2p) / Sn (3d) peak area ratio of 0.001 to 0.065 was prepared.
The contact resistance value before and after thermal aging was measured. In Table 4, P (2
The relationship between the peak area ratio of p) / Sn (3d) and the change over time in the contact resistance value is shown. Evaluation of the contact resistance value was set to 10 mΩ or less as OK and NG or higher as NG (the contact resistance value of the tin-plated material not subjected to oxidative deterioration is 5 to 10 mΩ).

[0023]

[Table 4]

Examples 1 to 3 showed excellent contact resistance characteristics without an increase in contact resistance value due to heat aging. Comparative Example 1,
In Conventional Example 1, the contact resistance value increased due to heat aging. Also,
Comparative Example 2 showed a high contact resistance value before being subjected to heat aging. Table 5 shows the evaluation of the contact resistance before and after the heat treatment of the tin-plated material which was subjected to the antioxidant treatment under various antioxidant treatment conditions. The evaluation of the contact resistance value was set to 10 mΩ or less as OK, and more as NG.

[0025]

[Table 5]

In Examples 3 to 19 and Comparative Examples 4 and 6, there was no increase in contact resistance value due to heat treatment, and excellent contact resistance characteristics were exhibited. However, in Comparative Example 4 and Comparative Example 6, there is no increase in the characteristics associated with an increase in the diphenyl phosphite concentration or the propanol concentration, and further increase in the concentration is economically useless. In Comparative Examples 3, 5, 7 to 9 and Conventional Example 2, the contact resistance value increased due to heat aging. Comparative Examples 10 and 11 showed high contact resistance values before being subjected to heat aging.

[0027]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, the tin or tin alloy plating material for terminals and connectors of electronic devices, electric parts, etc., in which the plating surface is difficult to oxidize and the contact resistance is less likely to deteriorate over time. And its manufacturing method are obtained, which is extremely useful in industry.

Claims (4)

[Claims] 1. A P (2p) of a tin or tin alloy plated surface obtained by X-ray photoelectron spectroscopy on a plated surface of a tin or tin alloy plated material obtained by plating tin or a tin alloy on copper or a copper alloy. / Sn (3d) peak area ratio is 0.003 to 0.05, and tin or tin alloy plated material for terminals and connectors of electronic devices, electric parts and the like having excellent surface contact resistance characteristics. 2. A water-soluble organic compound containing at least one phosphoric acid ester having an aromatic substituent or at least one phosphorous acid ester having an aromatic substituent after copper or a copper alloy is plated with tin or a tin alloy. Immerse in a treatment liquid containing a solvent,
A method for producing a tin or tin alloy plated material for terminals and connectors of electronic devices, electric parts and the like, which is characterized by performing anode electrolysis and has excellent surface contact resistance characteristics. 3. The treatment liquid comprises 0.1 to 10% by weight of a phosphoric acid ester having an aromatic substituent or 0.1 to 10% by weight of a phosphorous acid ester having an aromatic substituent and 5 parts by weight of a water-soluble organic solvent. An aqueous solution containing ˜50 wt%.
A method for producing a tin or tin alloy plated material for terminals and connectors of electronic devices, electric parts, etc., which has excellent surface contact resistance characteristics as described above. 4. A tin or tin alloy plating for terminals / connectors of electronic devices, electric parts and the like having excellent surface contact resistance characteristics according to claim 2 or 3, wherein anodic electrolysis is carried out at a voltage of 2 to 20 V and an electrolysis time of 1 to 60 seconds. Method of manufacturing wood.