Magnet and a motor component having a coating with anticorrosion and insulation

A motor component covered with a novel electrocoating that fails to detrimentally affects magnetic memory medium provided in a hard disc or other is provided. With enhanced edge covering ratio, an improved insulation coating is easily formed on the motor component. An insulation coating is electrodeposited on an Nd--Fe--B system plastic magnet, a stacked core of silicon steel, a die-cast motor base of aluminum or other motor component through cationic electrodeposition. The electrodeposition paint for use includes 12 ppm or less of tin content in the aqueous solution, 0.5% or less by weight of carbon black content in the aqueous solution, and, instead, has titanium dioxide and/or silicon dioxide added to pigment. The electrodeposited insulation coating, which has a specified thickness, is heated to temperatures ranging between 40.degree. C. and 90.degree. C. After such preliminary curing, temperatures are again heated to between 150.degree. C. and 190.degree. C. In the hard disc drive unit assembled of such electrodeposited components, no tin is scattered therefrom, thereby protecting memory content from collapsing, and providing enhanced anticorrosion and insulation.

FIELD OF THE INVENTION 
This invention relates to a magnet, a stacked core, a motor base or other 
motor component having excellent in anticorrosion and insulation 
properties, and particularly to a magnet, a stacked core or a motor base 
which is covered by an electrocoating, thereby providing superior 
anticorrosion and insulation. 
BACKGROUND OF THE INVENTION 
Conventionally, a stepping motor stacked core or other motor component is 
electrodeposited, thereby assuring good anticorrosion and insulation. 
For example, Japanese laid-open patent application No. 58-83559 proposes a 
method of insulating a stacked core of coil block for use in a stepping 
motor of a clock. In the method, by immersing the stacked core in aqueous 
epoxy solution containing amine, a cationic electrocoating of epoxy is 
formed on the stacked core, which is made a cathode for this purpose. 
Subsequently, the electrocoating is heat treated at temperatures ranging 
between 100.degree. C. and 300.degree. C. and is formed into an epoxy 
coating through condensation. 
However, in the prior-art electrodeposited motor component, as shown in 
FIG. 7, when the thickness of the coating on the surface of the component 
is T, the thickness t of the coating on the edge of the component tends to 
be smaller than thickness T. The physical quantity defined as t/T is an 
edge covering ratio. A lowered edge covering ratio causes imperfect 
insulation. To raise the edge covering ratio, the curing temperature after 
the electrodeposition needs to be lowered, for example: 
Conventionally, to lower the curing temperature, tin compound, for example, 
the compound of isobutyl tin oxide is generally added by about 0.05% by 
weight to the aqueous solution of electrodeposition paint, i.e., by about 
0.2% by weight to the coating. 
It was, however, reported that when the motor assembly of the stacked core, 
the magnet and the like with the insulation coating formed thereon in the 
aforementioned conventional manner was used in a hard disc drive unit, the 
content of memory in the hard disc collapsed. We reviewed this problem and 
concluded that the problem was caused by the content of the coating. 
SUMMARY OF THE INVENTION 
Wherefore, the object of the invention is to provide a motor component 
covered with a novel electrocoating, failing to detrimentally affect a 
magnetic memory medium, to raise the edge covering ratio and to easily 
form a coating with improved insulation on the motor component. 
Our research has and found that by applying an electrocoating to the motor 
component using an electrodeposition paint containing 12 ppm or less of 
tin and tin compound in the aqueous solution, the memory content can be 
protected from collapse. 
After consideration, we concluded that the reported memory collapse 
resulted from the tin and tin compound being released from the insulation 
coating and sticking to the surface of the magnetic memory medium. We 
succeeded in solving the problem by eliminating such cause. For this 
purpose, an electrocoating is formed containing only 50 ppm or less of tin 
and tin compound. Therefore, in present the invention no further tin 
content is added as in the prior art. 
In the electrodeposition paint of the present invention, carbon black is 
added to the aqueous solution only by 0.5% by weight or less, and titanium 
dioxide and/or silicon dioxide is added to the pigment. The pigment thus 
preferably contains a reduced quantity of carbon black, because the 
excessive content of carbon black would impair insulation, as further 
described below. 
The aqueous paint solution for use in electrodeposition painting generally 
contains water and paint in the rate of 3 to 1 or 4 to 1. Upon curing the 
tin content and the quantity of carbon black in the coating through heat 
curing, the final tin and tin compound in the electrocoating on the motor 
component can be 50 ppm or less. The quantity of carbon black in the 
electrocoating can be 2% by weight or less. 
Specifically, the electrodeposition paint for use can include the pigment 
content of 22% to 40% by weight of total solidified content, i.e., the 
content of pigment and resin. When using the paint containing the pigment 
content including titanium dioxide or silicon dioxide in such range, the 
edge covering ratio as well as the hardness of the insulation coating are 
enhanced. 
The motor component, other than the magnet, the invention relates to is, 
for example, a stacked core composed of 1% to 3% by weight of silicon and 
remaining percentage by weight of iron, of low carbon steel, or of pure 
iron, or a motor base composed of aluminum alloy. For use, such motor 
component is tightly wound with coil or is exposed to the outside, thereby 
requiring a thick and hard coating. By using the paint containing the 
pigment in the aforementioned range, the edge covering ratio and hardness 
of the insulation coating can be increased. 
On the magnet or permanent magnet, the electrocoating is formed preferably 
using an electrodeposition paint including a pigment content of 16% to 28% 
by weight of total solidified content. For use, the magnet is wound with 
no coil and fails to be exposed outside. Therefore, the magnet is 
different in conditions from the stacked core or the motor base. Recently, 
motors were made compact, thereby reducing the space inside the motors. 
The insulation coatings covering the magnet need not to be too thick. The 
body of the magnet referred to herein can consist of an Nd--Fe--B system 
plastic magnet, a hot compression molded magnet or a sintered magnet. 
When painting the motor component of the invention, first the 
electrodeposition paint having the tin and tin compound restricted to 12 
ppm or less in the aqueous solution is electrodeposited to the motor 
component. Subsequently, during preliminary heat treating the coating is 
heated to temperatures ranging between 40.degree. C. and 90.degree. C., 
and during second-step curing the coating is heated to temperatures 
ranging between 150.degree. C. and 190.degree. C. The method of painting 
the motor component is characterized by such two-step curing. 
The two-step curing enhances the edge covering ratio. Furthermore, pinholes 
made in the positions contacted by electrode pins for use in 
electrodeposition painting can be filled. According to the method of the 
invention, memory content is prevented from collapsing. Furthermore, the 
coating is made uniformly thick on the motor component, and good 
anticorrosion and insulation are assured. 
In the painting method, the electrodeposition paint for use contains only 
0.5% by weight or less of micro carbon black in relation to the aqueous 
solution. Instead of carbon black, titanium dioxide and/or silicon dioxide 
having a relatively large diameter is added to the pigment. 
For electrodeposition painting the stacked core composed of 1% to 3% by 
weight of silicon and the remaining percentage by weight of iron, of low 
carbon steel, or of pure iron or for electrodeposition painting the motor 
base composed of aluminum alloy, the electrodeposition paint for use 
preferably contains 22% to 40% by weight of pigment in the solidified 
content. For electrodeposition painting the Nd--Fe--B system plastic 
magnet, the hot compression molded magnet or the sintered magnet, the 
electrodeposition paint for use preferably contains 16% to 28% by weight 
of pigment in the solidified content. 
The first-step, preliminary heat treating is very important for eliminating 
pinholes or other made by later-mentioned hold projections in contact with 
the surface of the motor component or by gas discharged from the component 
being cured. The heat treating time period is selected such that the 
coating is fluid enough to fill the pinholes or other. The setting of heat 
treating time period varies with the preliminary heat treating 
temperature. When the preliminary heat treating temperatures range between 
40.degree. C. and 90.degree. C., the time period can be five minutes at 
minimum, thereby providing considerable heat treating effectiveness. The 
lower heat treating temperatures especially provide more heat treating 
effectiveness. 
For the second-step curing, the time period is selected to be long enough 
for the coating to be burnt and set, and also varies with curing 
temperatures. For example, at the temperatures ranging between 150.degree. 
C. and 190.degree. C., the time period is five minutes at minimum. 
The preliminary heat treating can be carried out while the temperature is 
raised at the rate of 20.degree. C. per minute or lower. The preliminary 
heat treating gives sufficient fluidity to the coating such that pinholes 
or other defective portions are covered by the coating. As far as the 
purpose is attained, the coating can be retained to cure in the 
appropriate temperature range for some period of time. The temperature 
does not have to be kept constant, and can be raised within the 
appropriate range during the preliminary heat treating. However, if the 
temperature is raised excessively fast, the period of time for the 
preliminary heat treating would be shortened, thereby resulting in 
imperfect covering of pinholes and other imperfections. 
In the invention the cationic electrodeposition painting is preferable. 
The insulation coating on the motor component of the invention contains 
only minor tin content. Therefore, the tin and tin compound is prevented 
from scattering, and the motor component, even if used in the hard disc 
drive unit, fails to cause a collapse of memory. 
The content of carbon black in the electrodeposition paint is decreased 
while the content of titanium dioxide and/or silicon dioxide is increased. 
Therefore, although the tin content is controlled to a minimum, optimum 
edge covering ratio can be assured. Especially, through two-step curing, 
the coating is made uniformly thick. Even the thickness of the coating 
formed on the edge of the motor component can be the same as that of the 
coating formed on the other surfaces of the component. The pinholes made 
in the surface of the coating can be concealed by the coating. 
Consequently, the insulation coating formed according to the invention can 
have a uniform thickness all over its surface and can provide enhanced 
insulation and anti corrosion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Embodiments of the invention are now detailed referring to the accompanying 
drawing figures. However, the invention is not restricted to the 
embodiments. 
FIG. 1 shows an annular Nd--Fe--B system plastic magnet 1 for use in a 
rotary part of a small-sized motor, and FIGS. 2A, 2B diagrammatically show 
an electrodeposition painting device for electrodeposition painting the 
plastic magnet 1. 
The electrodeposition painting device 10, as shown in FIG. 2A, is provided 
along a specified delivery path with a rinsing bath C1, a drip bath C2, a 
first electrodeposition bath C3, a first filtrate bath C4, a second 
electrodeposition bath C5, a second filtrate bath C6, a third filtrate 
bath C7, a drip bath C8 and a rinsing bath C9. Pure water is contained in 
the rinsing baths C1, C9, the aqueous electrodeposition paint solution is 
contained in the electrodeposition baths C3, C5, and specified filtrate is 
contained in the filtrate baths C4, C6 and C7. Work holders C10 are 
sequentially immersed in these treatment liquid, delivered along the path 
and then baked by a not-shown baking furnace. The dimension of these baths 
C1-C9 is adapted to the dimension of the work holders C10. The work 
holders C10 are delivered intermittently corresponding to each distance 
between the baths such that each work holder is inserted in each of the 
baths C1-C9 at the same time. Also the holders C10 are repeatedly lowered, 
stopped and lifted up such that they are immersed or retained for 
necessary period of time in respective treatment baths C1-C9. The 
immersing or retention time is predetermined such that the coating having 
a predetermined thickness is formed on the surface of each of works C16 
held by the work holders C10. In the electrodeposition baths C3, C5, the 
aqueous electrodeposition paint solution is stirred such that the 
concentration thereof can be made constant. 
The work holders C10 are, as shown in FIG. 2B, provided for holding a 
multiplicity of works C16 with a multiplicity of pointed hold projections 
C12 consisting of leaf spring or other material arranged on a hold plate 
C14. Each work C16 is held or contacted by three hold projections C12. 
As shown in FIG. 2A, the work holders C10 are intermittently delivered from 
bath to bath. As shown in FIG. 8, however, the work holders C10 can be 
continuously immersed in a large-sized electrodeposition bath C20 for a 
specified period of time. 
The aqueous paint solution for use in the electrodeposition painting 
contains water, solvent and solidified paint content in the respective 
percentages of 72, 3 and 25. In the same manner as in the conventional 
electrodeposition paint, the solidified paint content is composed of 75% 
by weight of resin content and the remaining percentage by weight of 
pigment content. The contained solvent is known for facilitating mixing of 
water with the solidified paint content. The electrodeposition paint for 
use in the embodiment is characterized in the following two points. 
1 The pigment content contains a reduced quantity of carbon black and, 
instead, is supplemented with titanium dioxide and/or silicon dioxide, 
imparting a color of white or gray. The carbon black contained in the 
aqueous paint solution at 0.5% or less by weight. 
2 Different from the conventional aqueous paint solution, no tin or tin 
compound is added. The aqueous solution of the invention contains little, 
for example, 12 ppm or less of tin or tin compound. 
The resin of the solidified paint is mainly composed of epoxy resin, in the 
same manner as the conventional electrodeposition paint. 
The aforementioned characteristic feature 2 can be easily confirmed by 
analyzing the electrodeposition paint through atomic absorption spectro 
photometry and emission spectral analysis. 
The cationic electrodeposition painting is preferable because metal is 
prevented from eluting from electrodeposited objects. 
The invention is further detailed in the following embodiment together with 
reference examples. 
FIRST EMBODIMENT 
The aqueous solution of electrodeposition paint containing the pigment 
content of 22% by weight in relation to the solidified paint content was 
applied in the electrodeposition painting device 10 shown in FIG. 2 to an 
annular Nd--Fe--B system plastic magnet having an outer diameter of 22.0 
mm, an inner diameter of 20.0 mm and a length of 10.0 mm under the 
following conditions, to form 25 .mu.m thick coating. The resulting edge 
covering ratio was 45%. 
Electrodeposition Painting Conditions 
1 Voltage: 200V to 300V 
2 Electrodeposition Temperature: 28.degree. C. 
3 Curing (Baking) Process: two-step curing 
First step: 80.degree. C..times.15 minutes 
Second step: 160.degree. C..times.20 minutes 
During the first heat treating, a furnace was heated to 80.degree. C. in 
advance and the electrodeposited magnet was inserted and retained in the 
heated furnace. The second curing was done in the same manner as in the 
first curing, except that the furnace was heated to 160.degree. C. in 
advance. 
First Reference Example 
For comparison, the annular Nd--Fe--B system plastic magnet identical to 
the magnet in the embodiment was electrodeposited in the painting device 
10 shown in FIG. 2, using the electrodeposition paint under the following 
conditions, thereby forming a 23 .mu.m thick coating on the magnet. The 
paint is almost identical to the paint for use in the embodiment. However, 
for the purpose of comparison with the embodiment, about 0.05% by weight 
of tin and tin compound is added to the aqueous solution. The resulting 
edge covering ratio was 30%. 
Electrodeposition Painting Conditions 
1 Voltage: 250V 
2 Electrodeposition Temperature: 28.degree. C. 
3 Curing (Baking) Temperature: 200.degree. C. 
4 Curing Time Period: 20 minutes 
Second Reference Example 
For reference, the annular Nd--Fe--B system plastic magnet identical to the 
magnet of the embodiment was electrodeposited in the painting device 10 
shown in FIG. 2 using an electrodeposition paint under the following 
conditions, thereby forming a 20 .mu.m coating on the magnet. Different 
from the embodiment, the paint contains 10% by weight or more of carbon 
black in relation to the pigment content (0.5% by weight or more of carbon 
black in relation to the aqueous paint solution), imparting color of 
black. In the same manner as the embodiment, however, the paint contains 
12 ppm or less of tin and tin compound in relation to the aqueous 
solution. The resulting edge covering ratio was 10%. 
Electrodeposition Painting Conditions 
1 Voltage: 250V 
2 Electrodeposition Temperature: 28.degree. C. 
3 Curing (Baking) Temperature: 210.degree. C. 
4 Curing Time Period: 20 minutes 
It is seen that the embodiment provides an increased edge covering ratio as 
compared with the first and second reference examples. 
Subsequently, the plastic magnets of the embodiment and the first and 
second reference examples were tested for anticorrosion and insulation. 
(1) Anticorrosion Test 
The magnets were retained in a humidity cabinet tester at 80.degree. C. in 
the atmosphere of relative humidity 95% for 96 hours to 500 hours. Results 
are shown in Table 1. 
TABLE 1 
______________________________________ 
ANTICORROSION 
RETENTION TIME 96 200 300 500 
______________________________________ 
EMBODIMENT .largecircle. 
.largecircle. 
.largecircle. 
.largecircle. 
REFERENCE EXAMPLE1 .largecircle. .largecircle. .largecircle. .DELTA. 
REFERENCE EXAMPLE2 .largecircle. 
.largecircle. x x 
______________________________________ 
In Table 1, 
.largecircle. denotes that no rust arises; 
.DELTA. denotes that the edge of a test piece gathers minute pointed rust 
that can be found on a 30 times microscope; and 
x denotes that the edge of the test piece gathers visible pointed rust. 
Subsequently, the test piece of the embodiment was prepared by gradually 
raising temperatures from room temperature to 100.degree. C. during 
first-step preliminary curing. Table 2 shows how the anticorrosion of test 
pieces is varied when the rate of raising temperatures from 30.degree. C. 
to 100.degree. C. is kept constant. The conditions of the second heat 
treating were the same as in the first embodiment. 
TABLE 2 
______________________________________ 
HEATING RATE ANTICORROSION 
BETWEEN 30.degree. C. 
HUMIDITY CABINET TEST: 
AND 100.degree. C. 80.degree. C. .times. 95%, 500 HOURS 
______________________________________ 
10.degree. C./MINUTE .largecircle. 
20.degree. C./MINUTE .largecircle. 
30.degree. C./MINUTE .DELTA. 
40.degree. C./MINUTE x 
______________________________________ 
In Table 2, 
.largecircle. denotes that no rust arises; 
.DELTA. denotes that the edge of a test piece gathers minute pointed rust 
that can be found on a 30 times microscope; and 
x denotes that the edge of the test piece gathers visible pointed rust. 
It is seen from Table 2 that even if the furnace is heated slowly at the 
rate of 20.degree. C. per minute, excellent anticorrosion is provided. In 
this case, the period of time during which temperatures are in the range 
between 40.degree. C. and 80.degree. C. is regarded as important. The 
difference between temperatures before and after the raising of 
temperature is not so important. Therefore, there can be a difference of 
about 10.degree. C. 
(2) Insulation Test 
The magnets of the embodiment and of the first and second reference 
examples were tested using a withstand voltage meter for withstand voltage 
with alternating electric power source. Results are shown in Table 3. 
TABLE 3 
______________________________________ 
TEST VOLTAGE (V) 100 200 500 
______________________________________ 
EMBODIMENT .largecircle. 
.largecircle. 
.largecircle. 
REFERENCE EXAMPLE 1 .largecircle. .largecircle. .DELTA. 
REFERENCE EXAMPLE 2 .largecircle. .DELTA. x 
______________________________________ 
In Table 3 
.largecircle. denotes that no test piece can have electric continuity 
therethrough; 
.DELTA. denotes that one test piece among ten can have electric continuit 
therethrough; and 
x denotes that one test piece among two can have electric continuity 
therethrough. 
As seen in Table 3, the coating for the plastic magnet of the embodiment is 
superior in anticorrosion and insulation to the coating for magnets of the 
first and second reference examples. 
The Nd--Fe--B system plastic magnet identical to the magnet of the 
embodiment was tested to see how the anticorrosion and edge covering ratio 
are varied when the burnt residue or ash content equivalent to the pigment 
included in the solidified content is changed. Results are shown in Table 
4. In the test the desired thickness of coating was 25 .mu.m. The 
anticorrosion test was conducted at temperature of 80.degree. C., relative 
humidity of 95% and retention time period of 200 hours. The other test 
conditions were the same as in the aforementioned first embodiment if the 
tin content in the aqueous solution is 12 ppm or less. During curing, 
temperatures were kept constant in the same way as in the first 
embodiment. 
TABLE 4 
______________________________________ 
ASH CONTENT EDGE COVERING RATIO 
(% BY WEIGHT) ANTICORROSION (%) 
______________________________________ 
10 .DELTA. 10 
16 .largecircle. 35 
22 .largecircle. 45 
28 .largecircle. 50 
34 .DELTA. 55 
______________________________________ 
NOTE: THE ASH CONTENT IS REPRESENTED IN PERCENTAGE BY WEIGHT IN RELATION 
TO 100% BY WEIGHT OF SOLIDIFIED CONTENT. 
In Table 4, 
.largecircle. denotes that anticorrosion is excellent; and 
.DELTA. denotes that test pieces gather pointed rust to some degree. 
As seen in Table 4, the ash content of Nd--Fe--B system plastic magnet is 
preferably between 16% and 28% by weight of the solidified content. When 
the ash content is outside this preferable range, the anticorrosion is 
deteriorated. 
From additional test it is found out that two-step curing is superior to 
curing only at high temperatures. The paint coating with no pinholes made 
therein can be obtained through the two-step heat treating: during the 
preliminary curing the furnace is heated to between 40.degree. C. and 
90.degree. C., preferably between 60.degree. C. and 80.degree. C. for 
appropriate period of time between 5 minutes and 180 minutes, preferably 
between 10 minutes and 60 minutes and during the second-step curing the 
electrocoating is cured for 5 to 180 minutes, preferably for 10 to 60 
minutes. If second-step curing temperatures are below 150.degree. C. 
during the second-step curing, the electrocoating is insufficiently cured 
and outgasses, and cannot bear during practical use. If the temperatures 
exceed 190.degree. C. alloy powder is oxidized, the magnetic properties 
are deteriorated and the magnet is largely deformed. Therefore, the 
second-step curing temperatures preferably ranges between 150.degree. C. 
and 190.degree. C. 
Since the preliminary heat treating precedes the second-step curing, 
uncovered portions or pinholes made by the electrode pins or the hold 
projections C12 having contacted the surface of the magnet are filled, 
thereby preventing the surface of the magnet from being exposed outside. 
Especially, in FIG. 5, a solid line shows an insulation coating 5 formed 
on the plastic magnet 1 through two-step curing, and a dotted line shows 
the insulation coating formed through only one step curing at high 
temperatures. As shown in FIGS. 4 and 5, pinholes are concealed through 
the two-step curing, thereby enhancing the insulation and anticorrosion. 
For the object to be electrodeposited, by replacing the magnet of the 
embodiment by a stacked core for use in a small-sized motor composed of 1 
to 3% by weight of silicon and the remaining percentage by weight of iron, 
the aforementioned test was conducted. Results are shown in Table 5. The 
desired thickness of the electrocoating on the stacked core was 50 .mu.. 
The anticorrosion test was carried out at temperature of 80.degree. C. and 
relative humidity of 95% for retention time period of 200 hours. The other 
test conditions were the same as in the first embodiment. The 
electrocoating was cured through two-step curing. 
TABLE 5 
______________________________________ 
INSULATION EDGE 
ASH CONTENT WITHSTAND COVERING 
(% BY WEIGHT) ANTICORROSION VOLTAGE(V) RATIO (%) 
______________________________________ 
10 .DELTA. 200 10 
16 .largecircle. 300 30 
22 .largecircle. 500 45 
28 .largecircle. 1000 50 
34 .largecircle. 1500 50 
40 .largecircle. 2000 50 
50 .DELTA. 2300 50 
______________________________________ 
NOTE: THE ASH CONTENT IS REPRESENTED IN PERCENTAGE BY WEIGHT IN RELATION 
TO 100% BY WEIGHT OF SOLIDIFIED CONTENT. 
In Table 5, 
.largecircle. denotes that anticorrosion is excellent; and 
.DELTA. denotes that test pieces gather pointed rust to some degree. 
As seen in Table 5, although the electrocoating on the stacked core 
contains more ash content relative to solidified paint content than that 
on the magnet, excellent properties are provided. Specifically, the ash 
content preferably ranges between 22% and 40% by weight. Additional test 
shows that superior electrocoating can be obtained through two-step heat 
treating: during the first heat treating the electrocoating is cured 
between 60.degree. C. and 80.degree. C. for 10 to 60 minutes and during 
the second curing it is cured at high temperatures ranging between 
150.degree. C. and 190.degree. C. for 5 to 180 minutes, preferably for 10 
to 60 minutes. 
Again by replacing the stacked core by a die-cast motor base consisting of 
aluminum alloy, tests were conducted and the same results as in the 
stacked core were obtained. 
Subsequently, the magnet 1, a stacked core 2 and an aluminum die-cast motor 
base 3 were electrodeposited using the electrodeposition paint containing 
little tin content, were cured through the two-step process, and were 
assembled together into a hard disc drive unit 4 as shown in FIG. 3. As a 
result of operating the hard disc drive unit 4, no memory content 
collapsed. Since these components 1, 2 and 3 are provided with improved 
insulation and anticorrosion, they are durable and can withstand-even long 
use. 
As aforementioned, the invention is not restricted to the aforementioned 
embodiments. Various modifications and alterations are possible within the 
scope of the invention. For example, in the embodiment, the annular 
plastic magnet for use in the rotary part of the motor, the stacked core 
and the motor base were electrodeposited. Alternatively, a magnetic 
anisotropic, hot compression molded magnet or a sintered magnet can be 
electrodeposition painted. For the stacked core, a laminated configuration 
consisting of steel plates as shown in FIG. 6 can be electrodeposition 
painted. The stacked core can be composed of silicon steel, low carbon 
steel or pure iron. The motor components can also be used in parts other 
than the rotary part of the motor. 
As detailed above, the magnet and the motor component like the stacked core 
and the motor base, provided by the invention, are superior in 
anticorrosion and insulation. Therefore, by assembling these into 
electronic equipment, enhanced reliability can be assured. Especially, 
since the electrocoating contains little tin content, the hard disc or 
other electronic peripheral equipment is prevented from being adversely 
affected by too much tin content, thereby assuring long and stable use.