JP3289526B2 - Magnetic steel sheet for printed circuit board of small precision motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic steel sheet suitable for a printed circuit board of a small precision motor used for various electronic equipment such as OA equipment and VTR.

[0002]

2. Description of the Related Art Conventionally, printed circuit boards are often used in small precision motors used in various electronic devices such as OA devices and VTRs. As a printed circuit board,
From the standpoint of insulation, a copper-clad laminate is mainly used in which a copper foil is bonded to a resin substrate such as paper phenol via an adhesive layer such as an epoxy resin. When this printed circuit board is used as a motor component, a steel sheet having a thickness of 1.0 to 1.2 mm is used as a structural frame by superimposing. In addition, since a resin printed board does not easily transmit magnetic flux, a stator portion forming a magnetic path is required. Although the frame also serves this role, the stator may be formed by separately laminating electromagnetic steel sheets.

In recent years, the use of an electromagnetic steel sheet as an iron substrate has been studied in order to use an iron substrate instead of a resin substrate such as paper phenol and to improve the characteristics of a motor. Printed circuit boards made of magnetic steel sheets have excellent electromagnetic properties and also have sufficient strength to also serve as structural members for motors such as structural frames.
This is useful for further downsizing, higher performance, or lower price of the motor. However, electrical steel sheets are usually covered with an inorganic or semi-organic insulating film, so when an epoxy resin or the like is applied on this insulating film and copper foil is adhered, normal printing such as etching and partial soldering is performed. There is a problem that the resin layer is easily peeled off in the substrate forming process.

[0004] For this reason, it is also practiced to apply an epoxy resin or the like and then attach a copper foil after grinding and removing the insulating film of the magnetic steel sheet. In this case, however, the surface of the magnetic steel sheet is rusted in a substrate forming process. There is a problem that the rust easily causes the resin layer to peel off.

[0005] In order to solve the above-mentioned problems, there is disclosed a technique in which metal plating is applied to a base steel sheet. For example, Japanese Patent Publication No. 2-56025 discloses that Si is 0.5 to
3.5% by weight, thickness 0.50mm or more, 1.5mm
On the following silicon steel sheet surfaces, Sn, Zn, Ni, Cr, C
5 g of one or more selected from u and Al
/ M ² or more and 150 g / m ² or less, it has excellent electromagnetic characteristics, has sufficient strength to also serve as a structural member of a motor, and further has a resin coating and a copper foil which are the usual steps for producing a printed circuit board. Discloses a steel sheet having excellent adhesion to a resin layer even after passing through steps such as sticking, etching, and soldering, and further having excellent corrosion resistance.

[0006]

However, in the above-mentioned technology, although the adhesion between the metal-plated silicon steel sheet and the resin layer is somewhat improved, it can be maintained for a long time in a severe environment of high temperature and high humidity. Then, there is a problem that blistering and peeling occur between the metal plating layer and the resin layer applied thereon, and the durability is not yet sufficient.

The present invention has been made in view of the above circumstances, and has as its object to provide an electromagnetic steel sheet for printed circuit boards having excellent durability.

[0008]

The structure of the present invention for solving the above-mentioned problems is as follows. (1) Surface roughness is center line average roughness Ra of 0.5 to 1.0
.mu.m and a thickness of 0.5 to 7 wt.
On at least one surface of a 5-1.0 mm silicon steel sheet,
Has a zinc-based plated layer of 0.3 to 4.0 g / m ^2, resistance having a phosphate film of 0.5 to 3.0 g / m ² thereon
Electromagnetic steel sheet for printed circuit boards of small precision motors with excellent durability .

(2) In the above invention, an electromagnetic steel sheet for a printed circuit board of a small precision motor having excellent durability, wherein the zinc-based plating layer is a zinc plating layer and the phosphate film is a zinc phosphate film.

[0010]

[0011]

The present invention will be described below. In the present invention,
When electromagnetic steel sheets are used as printed circuit boards, the presence of a phosphate film is important to exhibit excellent durability, and a base plating layer is required to form the phosphate film quickly and efficiently. There is a great feature in that a zinc-based plating layer is used.

A zinc plating layer having an adhesion amount of 2.8 g / m ² is formed on a surface of a silicon steel sheet having a center line average roughness Ra of 0.8 μm and a thickness of 0.8 mm by electroplating using a zinc sulfate bath. After that, a phosphate treatment was further performed thereon to prepare a magnetic steel sheet having a phosphate film having an adhesion amount of 0.2 to 3.4 g / m ² formed thereon. A 100 μm-thick epoxy resin was applied to this magnetic steel sheet, and then a 35 μm-thick copper foil was pressed and heated thereon to form a substrate. FIG. 1 shows the result of examining the durability of this substrate.

The phosphate treatment was carried out using a zinc phosphate treatment solution for zinc plating (Bonderite BP-3312 manufactured by Nippon Parkerizing Co., Ltd.) to form a zinc phosphate film.

In the durability test, the substrate was left in a steam bath at 60.degree. C. for 3 hours, and then immersed in a solder bath at 260.degree. C. for 3 minutes.
The presence or absence of peeling was visually observed. According to the degree of observation, ○ indicates that no blistering or peeling was observed, △ indicates that slight blistering or peeling was observed, and x indicates that significant blistering or peeling was observed. did.

From this figure, in order to obtain good durability, it is necessary to set the amount of the zinc phosphate coating to 0.5 to 3.0 g / m ² . 0.5 g / m of zinc phosphate coating
^If it is less than ² , sufficient adhesion cannot be exhibited because the amount of adhesion is too small. On the other hand, if the amount of adhesion exceeds 3.0 g / m ² , the durability of the zinc phosphate crystal is reduced due to the coarsening of the zinc phosphate crystals.

Further, in order to efficiently form a good phosphate film providing excellent durability, a zinc-based plating layer is formed on the underlying silicon steel sheet before the phosphate treatment. It is effective. Due to the presence of zinc in the plating layer, a necessary phosphate film can be formed in a short time when the phosphate treatment is performed.

This point will be described with reference to FIG. FIG. 2 shows that a zinc plating layer is formed by electroplating using a zinc sulfate bath on the surface of a silicon steel plate having a surface roughness of 0.8 μm in center line average roughness Ra and a thickness of 0.8 mm. It is a figure which shows the relationship between the amount of zinc plating and the adhesion amount of the produced | generated phosphate film about the case where a phosphate treatment was performed. In addition,
Phosphate treatment is a zinc phosphate treatment solution for zinc plating (Bonderite BP-331 manufactured by Nippon Parker Rising Co., Ltd.)
2) was used to form a zinc phosphate film.

If the amount of zinc plating is less than 0.3 g / m ² ,
The low formation rate of the zinc phosphate film hinders efficient production in a normal mass production process. This amount is 4.0
g / m ² , the adhesion amount of the zinc phosphate film becomes 3.0.
Since it exceeds g / m ² , durability decreases when used as a printed circuit board. Therefore, the amount of zinc plating is 0.1.
It is necessary to be ³ to 4.0 g / m ² .

Although the above description has been made on the case where a zinc phosphate film is formed on a galvanized layer, the present invention is not limited to this combination. A phosphate film having a predetermined adhesion amount as described above, and a zinc-based plating layer capable of forming a required phosphate film are widely included as the base plating layer. Examples of the zinc-based plating layer include a plating layer made of zinc plating, zinc-iron alloy plating, zinc-nickel alloy plating, zinc-aluminum alloy plating, or plating mainly containing these components. Zinc plating also includes hot-dip plating with zinc as a main component and a small amount of components such as aluminum and lead added thereto. In addition, a zinc phosphate film can be exemplified as a typical phosphate treatment film. In particular, when the zinc-based plating layer is a zinc plating layer and the phosphate film is a zinc phosphate film, a zinc phosphate film can be formed efficiently and with good controllability, and the formed zinc phosphate film has high performance. It is a particularly preferred combination because it exhibits excellent durability when an electromagnetic steel sheet having these films is used as a printed circuit board.

Further, when used for a printed circuit board, in order to obtain excellent durability with a copper foil, it is necessary to form a zinc-based plating layer and a phosphate film on a surface to which an adhesive resin is applied. is there. However, at least one of the zinc-based plating layer and the phosphate film may be formed on the surface on which the adhesive resin is not applied in view of corrosion resistance during the manufacturing process of the printed board or during use as the printed board.

The effect of the present invention can be further improved by subjecting the magnetic steel sheet of the present invention to a chromate treatment subsequent to the phosphate treatment.

In the present invention, Si in the silicon steel sheet is an essential component for ensuring electromagnetic characteristics. If the content of Si is less than 0.5% by weight, the desired electromagnetic characteristics cannot be obtained. Excess Si exceeding 7% by weight makes the steel sheet brittle. Therefore, Si needs to be 0.5 to 7% by weight. There are no particular restrictions on other components contained in the silicon steel sheet, and elements necessary for ordinary silicon steel sheets can be appropriately contained.

Further, the thickness of the silicon steel sheet is 0.5 mm or more,
It is necessary to be 1.0 mm or less. Strength is required for the substrate to also function as a structural frame, and for that purpose, a thickness of 0.5 mm or more is required. Thickness is preferable from the viewpoint of strength. However, if the thickness exceeds 1.0 mm, excessive strength results in wasteful use of materials and an increase in weight. Therefore, the thickness is set to 1.0 mm or less.

In the present invention, when the surface roughness of the silicon steel sheet is 0.5 to 1.0 μm in center line average roughness Ra, it is possible to exhibit more excellent durability in addition to excellent iron loss characteristics. it can. By setting the center line average roughness Ra to 0.5 μm or more, the durability is further improved due to the anchor effect with the applied resin. Further, the center line average roughness Ra is set to 1.0 μm.
Even if it exceeds m, the effect of improving the durability is small and, conversely, the iron loss characteristics deteriorate. Therefore, the center line average roughness Ra is desirably in the range of 0.5 to 1.0 μm.

Next, a method of manufacturing a steel sheet according to the present invention will be described. The steel sheet of the present invention can be manufactured by an ordinary method. That is, it is possible to produce a hot rolled sheet by melting and casting Si in steel within the scope of the present invention by a conventional method, and hot rolling the obtained slab.

The melting of steel may be performed by either a converter or an electric furnace.
Out-of-pile refining can also be applied if necessary. The casting may be either continuous casting or ordinary ingot. The slab may be formed not only by continuous casting but also by slab rolling after ordinary ingot making.

The steel sheet of the present invention may have a predetermined zinc-based plating layer and a phosphate film formed on a hot-rolled sheet as described later. Rolling is preferably performed to obtain the final product thickness. Moreover, you may intermediate-anneal a hot-rolled sheet before cold rolling as needed.
The surface roughness of the steel sheet can be adjusted by appropriately adjusting the surface roughness of the rolling roll during cold rolling.

The steel sheet rolled to the final product thickness is finally annealed to improve the magnetic properties. Although not particularly limited, the final finish annealing is usually performed by continuous annealing in 7 hours.
The annealing is performed at an annealing temperature of 00 to 1150 ° C. The annealing atmosphere is a non-oxidizing atmosphere, and is usually performed in a mixed atmosphere of hydrogen and nitrogen.

After the final annealing, the steel sheet is degreased and pickled, and then zinc-plated by an ordinary method. The zinc-based plating can be performed by a usual method such as electroplating, hot-dip plating or vapor deposition plating.

As zinc-based plating by electroplating,
Examples thereof include zinc plating, zinc-nickel alloy plating, zinc-iron alloy plating, and plating containing these as a main component.

Examples of the zinc-based plating by hot-dip plating include plating such as zinc plating and zinc-iron alloy plating.

In addition, the zinc-based plating may be performed by plating the above-mentioned ordinary method alone or in an appropriate combination.

After the zinc-based plating, the surface is subjected to a phosphate treatment by a conventional method to form a phosphate film.

When the chromate treatment is performed after the phosphate treatment, the chromate treatment can be performed by a conventional method.

[0035]

Embodiments of the present invention will be described below. The steel shown in Table 1 was melted, and the steel was subjected to continuous casting, hot rolling, pickling, cold rolling, and annealing to obtain a silicon steel sheet having a thickness of 0.50 mm. In addition, the surface roughness of the rolling roll of the cold rolling was adjusted so that the surface roughness of the steel plate was 0.8 μm or 0.3 μm as the center line average roughness Ra.

[0036]

[Table 1]

This steel sheet was subjected to galvanization by electroplating using a zinc sulfate plating bath, and further subjected to a phosphate treatment to prepare an electromagnetic steel sheet. The phosphate treatment was performed using a zinc phosphate treatment solution for zinc plating (Bonderite BP-3312 manufactured by Nippon Parker Rising Co., Ltd.). An epoxy resin having a thickness of 100 μm is applied on the above-mentioned electromagnetic steel sheet, and a thickness of 3 μm is applied thereon.
A 5 μm copper foil was heated and pressed to form a substrate. The substrate was left in a steam bath at 60 ° C. for 3 hours.
After being immersed in a solder bath at 0 ° C. for 3 minutes, the end face of the substrate and the laminate surface were visually inspected for blistering and peeling.
Depending on the degree of the result, ○ indicates that no blistering or peeling was observed, □ indicates that slight blistering or peeling was recognized, and △ indicates that slight blistering or peeling was recognized. Those with remarkable swelling and peeling were rated "x".

For comparison, a case where no phosphate treatment was performed was also investigated. The magnetic steel sheets subjected to the test are shown in Table 2 together with the test results.

[0039]

[Table 2]

Inventive Example No. Nos . 2 to 4 have excellent durability .
Coating weight phosphate salt adhered amount with respect to Re this is outside the scope of the present invention No. 1, 5 and N without phosphate coating
o. No. 7 is inferior in durability. Plating weight and phosphate weight
Is within the range of the present invention, but the center line average roughness Ra is
No. out of range. 6 (Reference Example)
Poor durability.

[0041]

The electromagnetic steel sheet of the present invention exhibits excellent durability when used as a printed circuit board because a phosphate coating film of a predetermined amount is formed on the zinc-based plating layer. Further, when the surface roughness of the silicon steel sheet is in a specific range, the durability is further improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the amount of zinc phosphate film deposited and the durability of a substrate.

FIG. 2 is a diagram showing the relationship between the amount of zinc plating and the amount of zinc phosphate film deposited.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-26247 (JP, A) JP-A-54-98926 (JP, A) JP-A-5-271883 (JP, A) JP-A-4- 206609 (JP, A) JP-A-63-277715 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 5/00-5/26 H05K 1/05 B

Claims (2)

(57) [Claims] 1. The surface roughness is 0.5 as a center line average roughness Ra.
0.3 to 4.0 g / m ² of zinc on at least one surface of a 0.5 to 1.0 mm thick silicon steel sheet containing 0.5 to 7% by weight of Si. An electromagnetic steel sheet for a printed circuit board of a small precision motor having excellent durability , comprising a base plating layer, and a phosphate film of 0.5 to 3.0 g / m ² thereon. 2. The zinc-based plating layer is a zinc plating layer,
The electromagnetic steel sheet for a printed circuit board of a small precision motor having excellent durability according to claim 1, wherein the phosphate film is a zinc phosphate film.