JPH0226246A - Manufacture of steel plate for iron printed board - Google Patents

Abstract

PURPOSE:To improve rust resistance by thin plating without necessity of special plating pretreatment by plating with double layers 1.0-30.0g/m<2> of total plating amount in the order of Ni, Sn, Zn from the side of a steel plate on the surface of a silicon steel plate containing 0.5-3.0% of Si, and then heat treating it at 200-350 deg.C for a short time. CONSTITUTION:Metal to be plated from a steel plate side to a first layer is Ni or Sn to be alloyed with base iron at a relatively low temperature, and subsequently plated with Sn of a second layer in case of Ni of first layer, or Ni in case of Sn of the first layer. Then, Zn plating is conducted as a third layer, and heat treated for alloying. Its heat treating condition is 200-350 deg.C for a short period of time. The Ni or Sn of the first layer is alloyed with base iron having SiO2 oxide layer by alloying heat treatment to improve adhesive properties with the base iron. Naturally, it is also alloyed with the Sn or Ni of second layer and Zn plated in double layer to a third layer thereby to form an alloy plating layer having excellent rust resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a steel plate suitable for iron-based printed circuit boards used in OA equipment, AV equipment, etc.

[Prior Art] Iron-based printed circuit boards made of silicon steel plates have come to be used for motors used in OA equipment, AV equipment, and the like. This allows the silicon steel plate to form a magnetic path and also serves as a motor frame.

Conventionally, JP-A-81-142939 discloses a method suitable for printed circuit boards in which the surface of a silicon steel plate is plated with 5 to 150 g/d of one or more of Sn, Zn, Ni, Cr, Cu, and /J. A steel plate was provided, and also,
No. 243119, Japanese Patent Application Laid-open No. 63-26398,
JP-A No. 63-35745 proposes, for the purpose of improving plating adhesion, that the former proposes plating before annealing, and the former 2 and 3 propose removing the oxidized layer on the surface of the steel sheet before plating. ing.

[Problems to be Solved by the Invention] The proposal in JP-A-01-241119 specifies a maximum plating amount of 150 g/nf (lower limit is 5 g/nf), which has the drawback of increasing costs due to thick plating. have. Next, in the case of JP-A-81-24-3119, there is a drawback that Zn plating, which is most effective for improving rust resistance, cannot be applied. Furthermore, in Japanese Patent Application Laid-open Nos. 83-28398 and 1983-35745, it is necessary to newly install a black for grinding the oxide film, which has the disadvantage of increasing manufacturing costs.

In the present invention, silicon steel sheets are manufactured under normal conditions and processes, and then pre-treated (degreasing, pickling) on an inexpensive general plating line.
To provide a steel plate for iron-based printed circuit boards that is thinly plated under certain conditions and has excellent adhesion to a base steel plate and rust resistance.

[Means for Solving the Problems] The present invention is based on the surface of a silicon steel plate containing 5i (1.5 to 3.0%), in which the total plating amount is 1.0 to 30% in the order of N1.Sn and Zn from the steel plate side. .After performing multilayer plating of Or/r+f,
This is a method for manufacturing a steel plate for iron-based printed circuit boards, characterized in that heat treatment is performed for a short time at a temperature of 200 to 350°C, and the order of multilayer plating is Sn from the steel plate side.

It is preferable to use Ni or Zn.

This will be explained in detail below.

In the present invention, the metal plated from the steel plate side to the -th layer is:
The second layer is N1 or Sn, which alloys with the base iron at a relatively low temperature, and the second layer is plated with Sn if the second layer is N1, and is subsequently plated with N1 if the second layer is Sn. Then Zn as the third layer
Plating is applied and heat treatment for alloying is applied.

The heat treatment conditions ξ are 200 to 350°C for a short time.

Through this alloying heat treatment, the Ni or Sn of the -th layer becomes
It is alloyed with the base iron having a SiO2-based oxide layer and improves the adhesion with the base iron, and as a matter of course, the Sn of the second layer
Alternatively, it is alloyed with N1 and Zn multilayer plated on the third layer, forming an alloy plating layer with excellent rust resistance.

Then, if necessary, post-treatment such as chromate treatment or phosphate treatment is performed.

Figure 1 shows N1. S n, Z n multilayer plating (each plating amount is N11.0.sn 2.O, Zn 1.
Og/rr? ) is a cross-sectional explanatory diagram. Figure 2 (a) shows the analysis results in the plating depth direction using the GDS method in that state, and Figure 2 (b) shows the same analysis results after heat treatment (350°C for 10 seconds). be. Next, Figures 3 and 4 (a) and (b) show Sn, Ni, Zn multilayer plating (Sn1.0°Ni 2.0.Zn 1.Og/rrf
) The results shown in Figures 1 and 2 are similar to those shown in Figures 1 and 2.

Naturally, the degree of alloying varies depending on the heat treatment conditions, but as long as the heat treatment conditions are within the scope of the present invention, excellent adhesion to the base iron and rust resistance are ensured.

The reasons for the limitations of the invention will be explained in detail below.

First, the reason why the S1 content of the silicon steel plate was limited to 0.5 to 3.0% is that if it is less than 0.5%, the formation of a magnetic path is insufficient.
This is because it is unsuitable as a printed circuit board for motors. Depending on the application of the motor, the S1 content may be 0.5%.
However, in this case, adhesion can be obtained without alloying the plating metal with the base iron by heat treatment, which is the main component of the present invention.

In addition, if the St content exceeds 3.0%, the thickness of the St oxide layer is so thick that even if the heat treatment of the present invention is applied, alloying of the plating metal and the base iron will be insufficient, resulting in insufficient plating. Adhesion is not ensured.

Next, the reason for limiting the plated metal will be described.

The reason why the plating metal of the first layer and the second layer is N1 or Sn is that these metals are easily alloyed with iron at a relatively low temperature. Zn was selected as the plating metal for the third layer because Nt, the plating metal for the first and second layers, was chosen as the plating metal for the third layer.
Both S and N are electrochemically sensitive to iron in the atmosphere and cannot protect iron from sacrificial corrosion, and if exposed to a humid atmosphere for a long period of time, problems such as red rust forming from plating defects will occur. Therefore, the rust resistance of the plating layer was ensured by alloying Zn and Sn or N1 and Zn.

All alloys containing Zn, Ni, and Sn formed by this alloying process have N1. In addition to the excellent corrosion resistance of Sn (less corrosion loss of the metal itself), alloying with Zn also adds sacrificial anticorrosion ability, which improves rust resistance (red rust of iron from plating defects or cut edges is reduced). ) is significantly improved, and excellent rust resistance is ensured even with thin plating.

Next, regarding the limited range of plating amount, the reason why the total plating amount of overlapping plating metal was set to 1 to 30 g/rf was 1z
Although the rust resistance of alloyed plating is superior to that of single-layer or multi-layer plating of Ni, Sn, and Zn below lrd, the rust resistance is insufficient as a steel plate for printed circuit boards. be.

In addition, if it exceeds 30 g/rd, the alloyed plating layer will have poor workability compared to the normal single-layer or multi-layer plating of Ni, Sn, and Zn. This is because peeling occurs. That is, it is presumed that the alloyed plating layer partially forms an intermetallic compound, resulting in poor workability.

For this reason, if the plating layer is thin, there will be no problem, but if the plating is thick (30 g/rr? or more), part of the plating layer will peel off during the press punching process, and the plated layer will not match with the base iron, which is the purpose of the present invention. Excellent plating adhesion cannot be ensured.

Figure 5 shows an example of the relationship between the total plating amount and rust resistance of multilayer plating (multilayer plating is N1.Sn,
The material was Zn, and the heat treatment conditions were constant at 300° C. for 10 seconds. The evaluation method is the same as in the example).

Although the present invention does not specify any plating surface,
Single-sided plating and differential thickness plating can be applied as needed. In other words, the back side of the printed circuit board (the side opposite to the Cu foil) requires excellent rust resistance, so it is preferable to apply thick plating, whereas the insulating resin/Cu foil laminated side requires only adhesion and is rust resistant. If this is not necessary, the surface may be subjected to post-treatment such as thin plating or chromate treatment.

Next, the reason why the temperature of the heat treatment condition was set to 200℃ or higher is that below this condition, alloying with the base iron and alloying of the multilayer plating will not be sufficient, and plating adhesion and rust resistance will not be ensured. .

The temperature was set below 350°C because alloying by heat treatment beyond this level will not only not contribute to improving plating adhesion and rust resistance, but also cause excessive alloying with the base iron, which will actually deteriorate plating adhesion. By doing so, as well as by excessive heat treatment,
This is because problems such as oxidation of the plating surface layer, thermal strain remaining in the silicon steel plate after cooling, and deterioration of magnetism become apparent. Of course, excessive heat treatment is economically disadvantageous.

The heat treatment time is suitably very short, for example 3 to 30 seconds.

Next, the heating method is not particularly specified in the present invention, and commonly used hot air heating, electric resistance heating (heating by directly applying electricity to the copper strip), induction heating, etc. can be applied. Cooling conditions are not particularly specified either, and a cooling method suitable for the processing equipment may be applied. For example, rapid cooling with water spray, cooling with cold air, cooling with rolls, etc. can be applied.

Next, the present invention does not particularly limit the post-treatment after plating. This is because it is generally well known that phosphate treatment or chromate treatment after plating improves rust resistance and adhesion with organic resins, and should be carried out as necessary. Bye.

That is, post-treatment may be carried out only when the desired adhesion cannot be secured without post-treatment depending on the type of resin, or when the necessary rust resistance cannot be secured.

Furthermore, if the product is stored for a long period of time after completion of plating, an oxide film will form on the surface of the plating layer, so chromate treatment is also effective in such cases. However, such post-processing is not particularly related to the constituent elements of the present invention.
It can be applied as necessary.

[Example 1] Table 1 shows the composition of the silicon steel plate used. A normal cold-rolled steel plate was used as a comparison material.

Table 1 Next, plating was performed under the following conditions to determine plating adhesion,
Table 2 shows the results of evaluating the rust resistance.

(1) Pre-plating treatment - Degreasing - In a solution of NaOH 50g/R at 80℃,
Cathode electrolytic treatment 15A/d+g2X 2 seconds ■ Pickling...
H2SO4LOOK/(1, Cathode electrolytic treatment in 15-30℃ solution 15A/da2X 2 seconds (2) Plating conditions ■Sn plating... Sn 2"30g/1, phenol ψ sulfonic acid 200g, Q, bath temperature 40℃ Cathode electrolysis treatment: 15A/di2 (current application time varies depending on the amount of plating) ■N1 plating...Ni5048H20200g/N, H2SO4L5g
/I), Boric acid 40g/(1, Bath temperature 40℃ Cathode electrolytic treatment: 15A/d+g2 (Electrification time varies depending on the amount of plating) ■Zn plating... ZnSO47H20200g/jll, H2So4L
5g/II, bath temperature 40℃, cathode electrolytic treatment: 15A/da2 (current application time is plating ff
(3) Heat treatment conditions A...150°C x 20 seconds (outside the scope of the present invention) B...
200°C x 20 seconds (range of the present invention) C...300°C x
lθ seconds (〃) D...350°C x 5 seconds () E...370°C x 40 seconds (outside the scope of the present invention) (4) Post-treatment ■ Chromate treatment... CrO350g/(J, H2SO40, 5g/ρ Cathode electrolytic treatment: 15A/do+2 x 2 seconds ■ Phosphate treatment... A treatment bath (B t3080) solution manufactured by Nippon Parkerizing was used under the standard conditions used.

〔Evaluation methods〕

(1) Rust resistance... A salt spray test was conducted under the conditions of JIS Z-2731.
The mackerel-infested area was evaluated after 20 hours.

(Red - red rust, white - white rust) (2) Plating adhesion... After stretching the plated steel plate by 10% using a tensile tester,
The surface was peeled off with cellophane tape using Chiban N (LaO2) to evaluate the adhesion.

(◎-No peeling at all, 〇-Less than 5% peeling, △-15% peeling
(3) Appearance: Color tone, pattern, etc. were visually evaluated.

(Good - good, defective) As shown in Table 2, symbol 1 means that the 81 content of the steel plate is 0.
．． Since the amount is as low as 1%, the adhesion of the plating layer is good even without heat treatment, but since the multilayer plating is not alloyed, white rust, which is a corrosion product of Zn, is completely covered. It has occurred. Symbols 4 and 7 are 31 in which the total plating amount is outside the scope of the present invention.
．． The adhesion of the plating layer was poor at 5 g/rrr. symbol 8
Since there is no Zn coating on the third layer, red rust occurs all over the surface. Symbol 9 indicates that the total plating amount is 0.0, which is outside the scope of the present invention.
Red rust occurs over a wide area due to the small amount of 9g:/d, symbol 1
In No. 1, the heat treatment temperature was as low as 150° C., which is outside the scope of the present invention, so alloying was insufficient and all properties were poor. In the case of symbol 14, the heat treatment temperature is as high as 370° C., which is outside the scope of the present invention, so that the alloying of the plating layer progresses too much, resulting in poor rust resistance. Symbol 1B is 81 in the steel plate
Since the content is as high as 3.3%, which is outside the scope of the present invention, the adhesion between the plating layer and the base iron is poor even if proper heat treatment is performed.

On the other hand, symbol 2. 3. 5. 6.10.12
13, 15, 17, and 18, the Si content in the steel plate, the total amount of multilayer plating, and the heat treatment conditions were all controlled within the scope of the present invention, and all properties should be satisfied.

[Effects of the Invention] According to the present invention, by multi-layer plating specific plating metals in a specific order and performing alloying treatment under specific heat treatment conditions, plating can be achieved without the need for special plating pre-treatment. A steel plate for printed circuit boards with excellent adhesion, thin plating, and excellent rust resistance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of multilayer plating, and FIG. 2(a). Figure 1 (b) shows an example of the analysis results in the plating depth direction by the GDS method before and after heat treatment. Figures 3 and 4 (a)
, (b) is a chart showing cross-sectional views and examples of analysis results in other multi-layer plating, Figure 5 is a chart showing the relationship between the total plating amount and adhesion of multi-layer plating, and Fig. 6 is a diagram showing the relationship between the total plating amount and adhesion of multi-layer plating. It is a chart showing the relationship between the total plating amount and rust resistance.

Claims (2)

[Claims] 1. The surface of a silicon steel plate containing 0.5 to 3.0% Si is coated with Ni, Sn, and Zn in this order from the steel plate side, with a total plating amount of 1.
After multilayer plating of 0 to 30.0 g/m^2, 20
A method for manufacturing a steel plate for iron-based printed circuit boards, which comprises performing a short-time heat treatment at a temperature of 0 to 350°C. 2. 2. The method according to claim 1, wherein the order of multilayer plating is Sn, Ni, and Zn from the steel plate side.