JPH079074B2 - Surface-treated steel sheet for electronic device parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention is used as an electronic component of an electric product, and has excellent rust resistance and weldability on one side and excellent rust resistance and whisker resistance on the other side. The present invention relates to a surface-treated steel sheet for electronic device parts.

(Prior Art) Generally, as a surface-treated steel sheet used for electronic parts of electric products, an electrogalvanized steel sheet is used for those which are not required to be soldered, and a tin plate and a turn sheet are used for soldering. In addition, some of the whisker resistance is strictly required to be plated with lead-tin after processing the parts, and those requiring weldability are also plated with Ni or Ni-P after processing of the parts. It has been subjected.
In this way, the surface-treated steel sheet for electronic parts is in a state where the existing plated steel sheet is used properly according to the application, and for special applications, the parts are post-plated by a method such as barrel plating after processing, In some cases, the cost is very high, and inexpensive materials for cost reduction have been very strongly demanded in recent years.

On the other hand, the present applicant has proposed Japanese Patent Application No. 1-92075 a surface-treated steel sheet for electronic device parts, which is excellent in rust resistance, whisker resistance and solderability. As shown in FIG. 8, the gist of the invention of this prior application is that Ni, Sn, Zn are formed on the front and back surfaces of the steel sheet in order from the steel sheet side.
After plating, heat treatment Sn-Zn, Zn-Ni,
It is a surface-treated steel sheet for electronic device parts that has excellent rust resistance, whisker resistance, and solderability, characterized by forming a Sn-Ni, Fe-Ni alloy layer and further forming a chromate film layer by electroless treatment. . However, in this prior invention, the same alloy layer configuration is used on both the front and back surfaces of the steel sheet, so applications that require weldability on one side among electronic components, such as semiconductor cases, are satisfactory in terms of welding splash that occurs during welding. It wasn't going to happen.

(Problems to be Solved by the Invention) As described above, in electronic parts applications, particularly in semiconductor cases, rust resistance and whisker resistance are required on one side, and rust resistance and weldability are required on the other side. The present invention intends to provide a new material satisfying all the performances required for electronic parts which have been impossible to apply by optimizing the constitution of the surface treatment film and the surface roughness of the steel sheet. To do.

(Means for Solving the Problems) The present invention has special applications among electronic components, that is, one surface has rust resistance, whisker resistance, and the other surface has a rust resistance and a requirement that the weldability is excellent. For the first time, it was possible to separate each function according to the characteristics of the alloy layer to be formed and to combine very severe weldability for electronic parts with surface roughness control of the steel sheet.

The gist of the present invention is as follows.

(1) 0.05g / m ² or more Ni plating is applied on the other side of the steel plate with a surface roughness Ra of 0.4μ or more on one side, and 0.05 on this Ni plating layer.
Sn plating of g / m ² or more is applied on this Sn plating layer with 10 to 80% of the above Sn plating amount and Zn on one side.
After Ni plating of 0.10 g / m ² or more, the plating layer is alloyed by heat treatment, and Sn-Zn, Zn-Ni, Sn-on the other surface.
Ni, Fe-Ni alloy layer, Ni layer and Fe-Ni alloy layer or Fe-Ni alloy layer is formed on one side, further one side characterized by forming a chromate film layer on both layers A surface-treated steel sheet for electronic device parts that has excellent rust resistance and weldability, and has excellent rust resistance and whisker resistance on the other surface.

(2) Ni plating of 0.05 g / m ² or more on one surface of the steel plate with surface roughness Ra of 0.4μ or more, 0.05 on this Ni plating layer.
Sn plating of g / m ² or more is applied on this Sn plating layer with 10 to 80% of the above Sn plating amount and Zn on one side.
Apply 0.05 g / m ² or more of Ni plating on this Ni plating layer by 0.05 g / m ^2.
After applying Sn plating of m ² or more, the plating layer is alloyed by heat treatment, and Sn-Zn, Zn-Ni, Sn-Ni, Fe on the other surface.
-Ni alloy layer, Sn-Ni on one side, Fe-Ni alloy layer is formed on one side, further one side characterized by forming a chromate film layer on both layers is excellent in rust resistance, weldability, Surface-treated steel sheet for electronic equipment parts, the other side of which has excellent rust resistance and whisker resistance.

(3) Ni plating of 0.05 g / m ² or more on the other surface of the steel plate with surface roughness Ra of 0.4 μ or more on one surface, and 0.05 on the Ni plating layer.
Sn plating of g / m ² or more is applied on this Sn plating layer with 10 to 80% of the above Sn plating amount and Zn on one side.
Apply 0.05 g / m ² or more of Ni plating on this Ni plating layer by 0.05 g / m ^2.
After applying Zn plating of m ² or more, the plating layer is alloyed by heat treatment, and Sn-Zn, Zn-Ni, Sn-Ni, Fe on the other surface.
-Ni alloy layer, Zn-Ni on one side, Fe-Ni alloy layer is formed on one side, further one side characterized by forming a chromate film layer on both layers is excellent in rust resistance, weldability, Surface-treated steel sheet for electronic equipment parts, the other side of which has excellent rust resistance and whisker resistance.

FIGS. 4 and 5 show the alloy coating structure concept corresponding to claim 1 of the present invention, FIG. 6 is claim 2 of the present invention, and FIG. 7 is corresponding to claim 3 of the present invention.

Hereinafter, the limited ranges described in the claims of the present invention will be described for each plating layer surface.

First of all, regarding the Ni plating on the three-layer plating side, which has excellent rust resistance and whisker resistance, the purpose of Ni plating is to provide the effect as a base plating to improve the uniformity of the plating film as described above. This is to obtain rust resistance. Therefore, in order to sufficiently exert the effect as the Ni undercoat, the surface of the steel sheet needs to be coated to some extent uniformly, so the lower limit is 0.05 g / m ² . Regarding the upper limit, although the rust resistance improves as the adhesion amount increases, naturally it is preferably about 1.0 g / m ² because it leads to cost increase, but the present invention does not particularly limit the upper limit. .

Next, the limited range of the Sn plating amount will be described. As with Ni, the amount of Sn plating is required to be 0.05 g / m ² as the minimum amount of adhesion that satisfies rust resistance. In addition, the upper limit cannot be strictly defined because the amount of adhesion varies depending on the required rust resistance, but it is generally 5.0 g / m ² due to the cost.
The degree is preferred, but is not particularly limited in the present invention.

Next, the limited range of the Zn plating amount will be described. Regarding the amount of Zn plating, in the case of the present invention, the alloy layer formed after thermal diffusion has a great influence on rust resistance and whisker resistance.
Limited by the ratio with the Sn plating amount.

Fig. 1 shows the amount of Ni plating on the base 0.05-1.
Shows an example of the relationship between the percentage and rust incidence of Zn / Sn in 0g / m ^2, Sn plating weight 0.05 to 5.0 g / m ^2. The heat treatment conditions in this case were an electric resistance heating method with a heating temperature of 300 ° C. and a heating rate of 30 ° C./sec. As shown in the figure, the red rust generation after 120 hours in the humidity resistance test (60 ° C x 90% RH) decreases as the proportion of Zn plating increases, and the red rust disappears at the Zn / Sn ratio of 10%.
FIG. 2 also shows an example of the relationship between the Zn / Sn ratio and the generation of whiskers under the Sn and Ni deposition amount ranges and heat treatment conditions similar to those in FIG. As shown in the figure, the generation of whiskers decreases as the proportion of zinc increases, and Zn / Sn
When the ratio is 10% or more, the occurrence of whiskers disappears. However, if the Zn / Sn ratio exceeds 80%, it will come close to Zn plating this time, and whiskers will occur again.

As described above, the Zn plating amount is limited to 10% or more and 80% or less of the Sn plating amount from the viewpoint of rust resistance and whisker resistance.

Next, the plated surface side, which is particularly excellent in weldability and rust resistance, will be described.

First, for Ni shown in claim 1 and FIGS. 4 and 5 of the present invention, from the viewpoint of rust resistance, the lower limit of the coating amount is
The limit is 0.10 g / m ² . In addition, the upper limit is generally preferably about 5 g / m ² from the viewpoint of cost, but the present invention is not particularly limited thereto.

The difference between FIGS. 4 and 5 indicates that there are two types of structures of the alloy layer formed depending on the difference between the Ni plating amount and the heat treatment condition. In this case, the alloy layer consists of Ni, Ni-Fe alloy and Ni.
-Fe alloy only, but almost no effect on welding strength.

Next, Sn- shown in claim 2 and FIG. 6 of the present invention
Regarding Ni, the lower limit of the coating weight of each is 0.05 g / m ² from the viewpoint of rust resistance. In addition, the upper limit is generally preferably about 5 g / m ² from the viewpoint of cost, but the present invention is not particularly limited thereto. The Sn / Ni ratio is not particularly limited in the present invention because it changes depending on the metal to be welded. As an example, when the metal to be welded is Ni or Ni-plated plate, Sn / N against welding strength
It is 30 to 95% of the optimum range of the i ratio.

Next, Zn-Ni shown in claim 3 and FIG. 7 of the present invention
Also, from the viewpoint of rust resistance, the lower limit of the coating weight of each is 0.05 g / m ² . In addition, the upper limit is generally preferably about 5 g / m ² from the viewpoint of cost, but the present invention is not particularly limited thereto. The Zn / Ni ratio is not particularly limited in the present invention because it changes depending on the metal to be welded. As an example,
For Ni and Ni plated plates, the optimum range of Zn / Ni ratio to weld strength is 10-75%.

The composition of the plating film on the welding surface side has a relatively wide range of suitability for welding strength depending on the type of metal to be welded, but in electronic parts applications, not only the welding strength, but also the splash that occurs during welding is directly linked to short circuits in electronic circuits. You are very severely restricted to. In the present invention, this welding splash is significantly improved by controlling the surface roughness of the steel sheet, and it becomes possible to satisfy the weldability of electronic parts only by combining with the above-mentioned plating film composition. Fig. 3 shows the relationship between the original plate roughness and the weld splash occurrence rate for various welding optimum plating films. As shown in the figure, the type of plating film on the welding side (Ni, Ni-F
Almost no difference due to e-alloy, Ni-Sn alloy, Ni-Zn alloy: all of which are in the welding strength suitable range), and any of the plating films have a roughness of the original plate of 04 μRa or more and good splash generation. Therefore, the roughness of the original plate on the welding surface side is limited to 0.4 μRa or more, and the surface roughness of a general thin plate is 1.0 μRa.
The degree is preferable, but the upper limit is not particularly limited.

The composition and manufacturing conditions of various plated alloy coatings in this case are as follows.

Ni; Ni = 3.0g / m ² , heating temperature = 300 ℃, heating rate = 30
° C / sec Sn-Ni; Sn = 2.0, Ni = 0.5 g / m ^{2 for} each, heating temperature = 300
℃, heating rate = 30 ℃ / sec Zn-Ni; Zn = 1.0, Ni = 1.0 g / m ^{2 for} each, heating temperature = 300
℃, heating rate = 30 ℃ / sec Regarding the conditions and method of alloying heat treatment of plating film, it is necessary to carry out in a short time for industrial production,
In that case, the general conditions are a heating temperature of 150 to 400 ° C., and a heating rate of several degrees Celsius / second to several hundred degrees Celsius / second, preferably 300 ° C. and 30 ° C./second. Further, as a heating method, there are a heating furnace using electricity and gas, electric resistance resistance heating, high frequency induction heating, or a combination thereof, and in the manufacturing process, there is an electric current heating device in the current tin plating line, so it is recommended to use this Although preferred, the present invention is not particularly limited.

Finally, a chromate treatment is generally performed as a post-treatment for plated steel sheets. For this, electrolytic and electroless treatment methods can be adopted, and the coating amount is generally 1-10.
Within the range of 0 mg / m ^2, the weldability and whisker resistance are not affected, and the rust resistance is improved, and the amount thereof may be appropriately selected according to the required level of rust resistance.

(Examples) Hereinafter, the contents of the present invention will be described based on Examples.

Example 1 Cold rolled and annealed by a conventional method, and further surface roughness
After low-carbon cold-rolled steel sheet adjusted to 0.5 μRa or more is subjected to resin / pickling by the usual method, the treatment conditions shown in (1) are applied in order.
Ni plating, Sn plating under the treatment conditions shown in (2), and Zn plating under the treatment conditions shown in (3) were performed. The adhesion amount of each plating is shown in Table 1. Then, subsequently, a heat treatment for 3 seconds at a steel plate surface temperature of about 3 seconds is carried out in the atmosphere by an electric resistance heating method, and a Sn-Zn binary alloy is formed on the plating layer surface on one side.
Zn-Ni, Sn-Ni secondary alloy and Fe-Ni alloy are formed inside the plating layer, and Sn-Ni, Zn-Ni, Ni or Fe-Ni alloy is formed on the plating layer on the other surface. Formed. The component analysis (wt%) of Zn, Sn and Ni in the alloy layers formed on these surface layers was carried out by using X-ray fluorescence analysis and GDS (glow discharge emission spectroscopy) together, and the values are also shown in Table 1. It was shown to. Furthermore, after performing a chromate treatment under the conditions shown in (4), it was subjected to various evaluation tests.

(1) Ni plating bath conditions NiSO ₄ : 7H ₂ O: 200 to 300g / NiCl ₂ · 6H ₂ O: 0 to 50g / H ₃ BO ₃ 40g / plating conditions Bath temperature: 40 to 50 ° C Current density: 5 to 30A / dm ² (1) Sn plating bath conditions Tin sulfate: 20 to 30 g / Phenol sulfonic acid: 20 to 30 g / Ethoxylated α-naphthol sulfonic acid: 2 to 3 g / Plating conditions Bath temperature: 35 to 45 ° C Current density: 2 ~30A / dm ² (3) Zn plating bath conditions _{ZnSO 4 · 7H 2 O: 200~400g} / Na 2 SO 4: 50~150g / plating conditions bath temperature: 40 to 50 ° C. current density: 5~30A / dm ² (4) Chromate treatment Bath conditions CrO ₃ : 50 to 100 g / H ₂ SO ₄ : 0 treatment conditions Bath temperature: 40 to 50 ° C Current density: 0 A / dm ² (immersion only for about 5 seconds) Example-2 Example- Example 1 as chromate treatment conditions in No. 1-
This is an example in which (4) of 1 is replaced by (5) shown below, and other items are the same as in Example-1.

(5) Chromate treatment Bath condition CrO ₃ : 50-100g / H ₂ SO ₄ : 0.1-20g / treatment condition Bath temperature: 40-60 ° C Current density: 20-100A / dm ² Cr deposit: 1-100mg / m ² Comparative Example-1 Ni, Sn, Zn three-layer plating on both sides of the steel sheet in Example-1, after reflow heat treatment, Sn-Zn, Zn-Ni on both sides,
This is an example in which a Ni-Fe alloy was produced and the same treatment as (4) in Example-1 was performed as the chromate treatment condition, and other items are the same as in Example-1.

Comparative Example-2 The surface roughness of the steel sheet in Example-1 was 0.3 μRa or less, and the other items were the same as in Example-1.

Comparative Example-3 In Example-2, the surface roughness of the steel sheet is 0.3 μRa or less, and the other items are the same as in Example-2.

Comparative Example-4 An electroplated tin plate (referred to as # 50 tin plate) with a Sn plating amount of 5.6 g / m ^{2 on} one side and a total chromium amount of 8 mg / m ^{2 in} terms of metallic Cr in terms of the amount of chromate film applied on the surface. .

Comparative Example-5 An electrogalvanized steel sheet (referred to as EG20) having a Zn plating amount per one surface of 20.5 g / m ² and a chromate coating amount applied to the surface of the total Cr amount of 70 mg / m ^{2 in} terms of metal Cr.

Comparative Example-6 This is an electric nickel-plated steel sheet with a Ni plating amount of 30.0 g / m ² on one surface.

As described above, examples of the present invention and comparative examples are shown below (a) to
The evaluation test of (e) was performed to compare the characteristics.

(A) Humidity resistance test (only on the non-welded surface side) For the humidity resistance test, the test material was aged for 240 hours in an atmosphere of 60 ° C. and 90% RH. Evaluation is performed visually, and the evaluation criteria are: ○ red rust, white rust, discoloration, black rust does not occur, △ red rust, white rust, black rust does not occur, discoloration, × red rust, white rust, discoloration, black rust occurrence did.

(B) Whisker resistance test (only on the non-welded surface side) The whisker resistance test was performed by subjecting the test material to cylindrical drawing of φ100 x 30 mm, and then 3-6 in the same humidity resistance test at 60 ° C and 90% RH. It was allowed to stand for a month. The evaluation was carried out visually and with a scanning electron microscope, and the evaluation criteria were ○ no whisker generation and x whisker generation.

(C) Welding test (welding surface side only) The welding test uses a steel electrode with a diameter of 5 mm and targets Ni-plated steel plate for welding, with a pressing force of 50 to 200 kg / mm ² and a total current of ^{2 to 4} KA to obtain welding strength. The occurrence of splash was evaluated. The evaluation was as follows: good welding strength was good, bad was bad, large splash was bad, fine splash was good, and no splash was good.

The test results are summarized in Table 1 above.

(Advantages of the Invention) As described above, the present invention has excellent weldability and rust resistance on one side and excellent rust resistance and whisker resistance on the other side for use as electronic parts for welding. The present invention makes it possible to supply a surface-treated steel sheet for electronic parts, which is suitable for welding at low cost.

[Brief description of drawings]

FIG. 1 shows an example of the relationship between the ratio of the Zn plating amount to the Sn plating amount and the rust occurrence rate. FIG. 2 shows an example of the relationship between the Zn / Sn ratio and the occurrence of whiskers. FIG. 3 shows the relationship between the surface roughness of the original plate and the occurrence of welding splash. FIG. 4 shows an example of a conceptual diagram of the plating layer of the surface-treated steel sheet for electronic parts obtained by the method according to claim 1. FIG. 5 shows an example of a conceptual drawing of the plating layer of the surface-treated steel sheet for electronic parts obtained by the method of claim 1. FIG. 6 shows an example of a conceptual diagram of the plating layer of the surface-treated steel sheet for electronic parts obtained by the method of claim 2. FIG. 7 shows an example of a conceptual diagram of the plating layer of the surface-treated steel sheet for electronic parts obtained by the method of claim 3. FIG. 8 shows an example of a conceptual diagram of the plating layer of the surface-treated steel sheet for electronic parts obtained by the method of Japanese Patent Application No. 1-92075.

Claims (3)

[Claims] 1. A Ni plate having a surface roughness Ra of 0.4 μ or more on one side and a Ni plating of 0.05 g / m ² or more on the other surface of the steel plate on the Ni plating layer.
Apply Sn plating of 0.05g / m ² or more on the Sn plating layer.
Along with performing Zn plating of 10 to 80% of the plating amount, after performing 0.10 g / m ² or more Ni plating on the above-mentioned one surface, alloy the plating layer by heat treatment, and Sn-Zn on the other surface, Zn-Ni,
Sn-Ni, Fe-Ni alloy layer, a Ni layer and an Fe-Ni alloy layer or Fe-Ni alloy layer is formed on one side, further characterized by forming a chromate film layer on both layers Has excellent rust resistance and weldability, and the other surface has excellent rust resistance and whisker resistance. ^2. Ni plating of 0.05 g / m ² or more is formed on the other surface of the steel plate having a surface roughness Ra of 0.4 μ or more on one surface on the Ni plating layer.
Apply Sn plating of 0.05g / m ² or more on the Sn plating layer.
Zn plating of 10 to 80% of the plating amount is performed, and 0.05 g / m ² or more of Ni plating is applied on the one side and 0.
After applying Sn plating of 05 g / m ² or more, heat treatment is used to alloy the plating layer and Sn-Zn, Zn-Ni, Sn-N on the other surface.
i, Fe-Ni alloy layer, Sn-Ni, Fe-Ni alloy layer formed on one side, further characterized by forming a chromate film layer on both layers rust resistance, weldability A surface-treated steel sheet for electronic device parts that has excellent rust resistance and whisker resistance on the other side. 3. Ni plating of 0.05 g / m ² or more is formed on the other surface of the steel plate having a surface roughness Ra of 0.4 μ or more on one surface, on this Ni plating layer.
Apply Sn plating of 0.05g / m ² or more on the Sn plating layer.
Zn plating of 10 to 80% of the plating amount is performed, and 0.05 g / m ² or more of Ni plating is applied on the one side and 0.
After applying Zn plating of 05 g / m ² or more, heat treatment is used to alloy the plating layer, and Sn-Zn, Zn-Ni, Sn-N on the other surface.
i, Fe-Ni alloy layer, Zn-Ni, Fe-Ni alloy layer was formed on one side, and further a chromate film layer was formed on both layers, one side is rust resistance, weldability A surface-treated steel sheet for electronic device parts that has excellent rust resistance and whisker resistance on the other side.