Resin molded article bearing electric circuit patterns and process for producing the same

In a mold having a pattern forming portion composed of a magnetic material, a pattern is formed by magnetically depositing a magnetic material on the wall of a cavity of the mold, and a resinous material is then injected into the cavity for molding and simultaneously transferring the pattern onto the surface of thus molded article.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an electric equipment, in particular, 
imaging equipment such as photographic cameras or magnetic recording 
cameras, electronic office equipments such as copying machines or 
computers, or communication equipment, provided with electric or 
electronic circuits therein, and involving electronic circuit assembly by 
forming such circuits on rigid circuits boards or flexible circuit boards 
and incorporating such circuits in the electric equipment. 
More particularly, the present invention relates to a process for forming a 
circuit pattern on a resin molded article adapted for use as a body or a 
cover of an electric equipment, or an intermediate member to be mounted on 
said body or cover. 
2. Related Background Art 
In a photographic camera or a camera for video tape recorder, various 
circuits such as a light-measuring circuit, an exposure calculating 
circuit and an automatic focusing circuit for driving a diaphragm 
mechanism, a shutter mechanism, a lens etc., are required, and the 
components constituting such circuits, such as transistors, resistors, 
capacitors, coils, IC's, LSI's, etc. are soldered onto circuit patterns 
formed on rigid or flexible circuit boards. 
Due to the increasing use of electric control and the increasing complexity 
of electric circuits with highly integrated circuit components for 
achieving higher performance, cameras are requiring an increased number of 
circuit boards, and rationalization in electric circuit assembly is 
required for compactization, efficient equipment assembly and efficient 
replacement or repair of components. 
A flexible printed circuit can be provided in a narrow space due to its 
flexibility, but requires a certain space when the aforementioned 
components are fixed thereon by soldering. Also flexible printed circuits 
employed as connecting portions B3, B4 shown in FIG. 1 for connecting a 
photometric circuit block B1 and an exposure calculating block B2, results 
in a complicated assembly since said flexible circuit has to be placed 
over a long distance in the camera. These drawbacks, of course, are not 
limited to cameras but are generally found in electric equipment. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a process for producing a 
resin molded article bearing electric circuit patterns or terminals 
patterns and serving as a body, a cover or an intermediate member of an 
electric equipment, as well as such article. The above-mentioned object 
can be achieved, according to the present invention, by one of following 
two processes. 
In a first process, in forming a pattern with a patterning material 
containing a magnetic material on a mold for producing a molded article, 
said pattern is formed on a pattern supporting member, and said pattern is 
thereafter transferred onto a mold member. 
In a second process, there is provided a mask member for coating a 
patterning material in a required portion of the mold member, and said 
patterning material is coated through said mask member onto the mold 
member to form a pattern thereon. 
A further object of the present invention is to provide a process of 
assembly of an electric equipment utilizing the article obtained by either 
of the processes mentioned above. 
With respect to said further object, it is proposed to reduce the number of 
circuit boards such as rigid circuit boards or flexible circuit boards 
thereby realizing simple and reasonable form of circuit assembly and 
resolving the aforementioned drawbacks in the prior technology. 
The above-mentioned reduction in the number of circuit boards can be 
achieved by directly forming circuit patterns on a body or a cover of the 
electric equipment or an intermediate member to be fixed in said body. In 
the example shown in FIG. 1, a block 3 and circuit patterns B3, B4 for 
connecting the circuit blocks B1 and B2 are formed directly on a body, a 
cover or an intermediate member thereby dispensing with the portions of 
said circuit patterns B3 and B4. 
A still further object of the present invention is to provide a process of 
electric circuit assembly of forming circuit patterns on a face of said 
resin molded article and connecting circuit blocks, formed on other 
surfaces facing said face of the resin molded article, with circuit 
patterns formed thereon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
At first there will be explained a process in which a patterning material 
is supported by a pattern supporting member and is transferred onto a mold 
member, while making reference to FIGS. 2 to 5B. 
In FIG. 2, a mold 1 is composed of a male mold 2 and a female mold 3, which 
are composed of magnetic portions 2.sub.1, 3.sub.1 for example of carbon 
steel, and non-magnetic portions 2.sub.2, 3.sub.2 for example of BeCu 
manufactured by Nippon Glass, YHD-50 manufactured by Hitachi Metal, NM-II 
manufactured by Nippon Kokan, sintered cobalt metal manufactured by 
Mitsubishi Metal or austenite steel SUS 303 or SUS 304. A cavity face of 
the movable male mold 2 is provided, for forming a circuit pattern, with a 
circuit pattern forming portion composed of a magnetic material of a high 
magnetic permeability and a high saturation magnetic flux density, such as 
a low-carbon steel, SKD61, SKD11, NAK-55 manufactured by Daido Special 
Steel, ASSABXW-10 manufactured by Assab Special Steel, Ferrotic C 
manufactured by Chugai Denko etc. Also the cavity face of the fixed female 
mold 3 is provided with a magnetic member 4.sub.2 constituting a counter 
magnetic pole. 
Arrows 5 indicate magnetic flux passing through the mold, and there is 
provided a sprue 6 for injecting resin into the mold 1. Outside the 
magnetic portions 2.sub.1, 3.sub.1 there are provided unrepresented coils 
for generating the magnetic flux. In the above-explained structure, the 
magnetic flux applied to the mold 1 passes through the magnetic portion 
2.sub.1, reaches a maximum density in the pattern forming portion 4.sub.1, 
then passes through the counter magnetic pole 4.sub.2 and finally passes 
through the female mold 3. It is to be noted that the magnetic flux does 
not go through the non-magnetic portions 2.sub.2, 3.sub.2. Thus, on the 
cavity face of the movable female mold 2, the circuit pattern forming 
portion 4.sub.1 shows magnetic attraction while other portions do not. 
Consequently the circuit pattern forming portion 4.sub.1 forms a magnetic 
latent image. 
Then the mold 1 is half opened and a conductive material 7 capable of 
forming a circuit pattern is deposited onto said magnetic latent image. 
Said magnetic material 7 should be ferromagnetic and soft magnetic with a 
low retentive magnetic flux, since said material has to be magnetically 
attractable for forming a magnetic image and should be free of magneticity 
after the image is transferred. Such magnetic material is, for example, 
Fe, Co or Ni powder. 
FIG. 3 shows the details of the cavity and the vicinity wherein said 
material 7 is deposited, and there are shown trajectories of the magnetic 
flux in the cavity and in the vicinity thereof. The counter magnetic pole 
4.sub.2 performs a function of rendering the magnetic flux on the circuit 
pattern forming portion 4.sub.1 perpendicular to the cavity face. Such 
perpendicular magnetic flux to the cavity face provides uniform magnetic 
flux density over the entire circuit pattern forming portion 4.sub.1, thus 
forming an evident contrast between said portion and other portions, and 
realizes a uniform distribution of the material deposited on said portion. 
A circuit pattern is thus formed with the magnetic material on the cavity 
face of the movable male mold 2 according to the magnetic image, but 
magnetic material may also deposit on the cavity face of the fixed female 
mold as it also has magneticity. 
In order to avoid deposition of the magnetic material on the cavity face of 
the fixed female mold 3, there may be employed a supply method in case the 
magnetic material is powder. The magnetic material is electrostatically 
deposited on a thin plate 8, for example of acrylic resin, which has a 
form similar to that of the molded article and which can be inserted in a 
small gap of the parting line of the mold. The magnetic material deposited 
on said plate 8 is positioned at the movable side, maintained on the 
parting line and the mold is subjected to a magnetic field. Thus the 
magnetic material deposited electrostatically on the plate 8 moves in the 
air, by the stronger force of said magnetic field, to the cavity face of 
the male mold and deposited on the magnetic circuit pattern. No deposition 
takes place on the female mold in this case, since no magnetic material is 
present on the side of said female mold. Also the magnetic material facing 
an area outside the circuit pattern is not deposited by said electrostatic 
force. Thus this process only allows deposition of the magnetic material 
on the circuit pattern of the male mold even if the cavity face of the 
female mold is magnetized. 
Then, after the molds are mutually tightened, fused resin is injected 
through the sprue. After cooling, the molds are opened, and the obtained 
molded article 9 has a pattern of the magnetic material 7 transferred to 
the surface thereof, as shown in FIG. 5A. 
FIG. 5B shows an example in which circuit elements 10A, 10B, 10C are 
directly fixed on the surface of an article 9 molded according to a 
process shown in FIGS. 2 to 5A. 
The aforementioned magnetic material also contains a binder component such 
as a Ni-acrylic conductive paint manufactured by Fujikura Kasei Co. Said 
binder does not function in the formation of the magnetic image, but in 
the injection molding of the resin molded article. The binder contained in 
the magnetic image constituting the circuit pattern is easily fused or 
softened by the high temperature and high pressure of the injected resin. 
In the cooling step of the molded article, the binder is also cooled and 
solidifies, so that the magnetic image is transferred from the cavity face 
to the molded article. Since the binder is fused to the resin of the 
molded article, the transferred circuit pattern has a very strong adhesion 
to the molded article. 
The foregoing explanation has been limited to the formation of an electric 
circuit, but the present invention is not limited to such embodiment and 
is applicable to the manufacture of irregular resin molded products for 
example those with surface decorative designs by replacing the magnetic 
pattern or magnetic material. Also the present invention is applicable to 
RIM molding, LIM molding, cast molding etc. in addition to injection 
molding. 
As explained in the foregoing, the present invention allows to form a 
circuit pattern on the irregular surface of a resin molded article 
simultaneous with the molding and without any secondary process, by 
magnetically forming a circuit pattern with a magnetic material on the 
cavity face of a mold composed a magnetic portion and a non-magnetic 
portion. Also the circuit need not be positioned with respect to the 
molded article in the molding operation, and is satisfactorily adhered to 
the molded article. 
Now reference is made to FIGS. 6 to 12 for explaining a process in which 
the patterning material is coated with a mask member. 
FIG. 6 shows a magnetic circuit composed of a mold 104 and an exciting coil 
103 mounted on a molding machine. The mold 104 is composed of a movable 
mold plate 105 and a fixed mold plate 106, and a pattern forming portion 
on the surface of a cavity 107 is composed of magnetic members 105a, 106a 
such as of carbon steel, while other portions are composed of non-magnetic 
members 105b, 106b for example of SUS 303. A platen 100 and a tie bar 102 
of the molding machine are respectively composed of magnetic materials 
such as carbon steel. When energized, the exciting coil 103 generates 
magnetic flux 112 as indicated by arrows to generate a magnetic force on 
the surface of the magnetic members 105a, 106a of the cavity 107, whereby 
magnetic powder 109 can be attracted and deposited on said surface. 
At first the movable mold plate 105 is opened as shown in FIG. 7, and a 
mask 108 is positioned to mask the cavity of the non-magnetic portion 
105b, thereby exposing the magnetic portion 105a only, onto which the 
magnetic powder is to be deposited. Said mask 108 is composed for example 
of a metal, rubber or plastics and fixed on the movable mold plate 105 by 
suitable means. 
Then, as shown in FIG. 8, an electrostatic painting machine 110 is used for 
coating the exposed portion of the cavity face and the mask 108 with 
magnetic powder 109. Said magnetic powder is composed of a ferromagnetic 
conductive material and a binder component, and is obtained for example by 
mixing 90 wt. % of nickel powder of an average particle size of 2-3 .mu.m 
and 10 wt. % of acrylic resin powder as the binder component, in the fused 
state of said binder, then cooling the mixture and crushing said mixture 
into powder with an average particle size of 30 .mu.m. For said nickel 
powder there can be employed a product called Type 255 supplied by Inco 
Limited Japan, and for said acrylic resin there can be employed a product 
called Finedic A224S supplied by Dai-Nippon Ink Chemical Industries Co. 
The magnetic powder 108, when negatively charged with a voltage of 70 kV 
by the electrostatic painting machine 110 and coated on the grounded mold, 
is deposited on the magnetic portion 105a and on the mask 108, by the 
electrostatic force between said mold and powder. 
Then the mask 108 is removed from the movable mold plate 105. Thus, as 
shown in FIG. 9, the magnetic powder 109 forms a pattern only on the 
surface of the magnetic portion 105a of the cavity 107. 
Then, as shown in FIG. 10, the mold 104 is closed and the coil 103 is 
energized, thereby generating a magnetic force on the surface of said 
magnetic portion 105a as explained before and firmly holding the already 
deposited magnetic powder 109 by magnetic attraction. Subsequently a resin 
material 111 is injected in the cavity. Said injected resin 111 fills the 
cavity in such a manner that said magnetic powder 109 is embedded in the 
resin while it is supported by electrostatic attraction in a predetermined 
position of the cavity. Also the binder component, such as acrylic resin, 
contained in the magnetic powder 109 is softened or fused by the high 
temperature and high pressure of the injected resin 111, and solidifies 
simultaneously with the cooling of the injected resin so that the binder 
and the resin of the molded article show very strong mutual adhesion. 
FIG. 11 shows a molded article removed from the mold after cooling. The 
pattern of the magnetic powder 109 formed on the face of the cavity 109 
prior to molding is embedded in the injected resin 111 and transferred as 
a circuit pattern 113 on the surface of the molded article. 
In an example an exciting coil of 346 turns was energized with a current of 
60 Amperes, and polystyrene resin of 200.degree. C. was injected from an 
injecting cylinder with a pressure of 340 kg/cm.sup.2 into the cavity. 
Thus there was obtained a molded article, bearing a circuit pattern of a 
surface resistivity of 1 .OMEGA./cm.sup.2 formed by the transfer of said 
magnetic powder to a predetermined position. 
Thus the present invention allows to form a circuit on the irregular 
surface of a resin molded article simultaneous with the molding operation 
and without any secondary work step, by depositing magnetic powder by 
electrostatic coating on a cavity face of a mold composed of magnetic and 
non-magnetic portions to obtain a pattern, and molding resin material 
while magnetically maintaining said magnetic material. Also there is 
obtained a circuit with satisfactory adhesion to the molded article. 
Now reference is made to FIGS. 12 to 13E for explaining an example of 
electric circuit assembly employing a resin molded article obtained with 
the above-explained processes. 
FIG. 12 is a schematic cross-sectional view in which circuit boards 202a, 
202b are electrically connected to a molded article 201. Said molded 
article 201 constitutes a part of a body of a cover of the electric 
equipment or an intermediate member to be mounted on said cover or body, 
and is further provided with a projection 201a. 
A circuit pattern B3, corresponding to the circuit pattern shown in FIG. 1, 
is formed on the surface of the molded article 201, utilizing a mold for 
said article. A circuit pattern 202a, formed on the circuit board 202, 
constitutes a part of the circuit block B1 shown in FIG. 1. 
FIGS. 13A to 13E illustrate a process for forming the molded article 201, 
wherein shown is a mold 204 composed of a fixed mold plate 204A and a 
movable mold plate 204B, which are in turn composed of magnetic portions 
204a.sub.1, 204b.sub.1 and non-magnetic portions 204a.sub.2, 204a.sub.3, 
204b.sub.2, 204b.sub.3 and constitute a cavity 204c for forming said 
molded article. Said cavity 204c is composed of a portion 204c.sub.1 for 
forming a flat portion of said body or cover, and a portion 204c.sub.2 for 
forming a projecting internally from said flat portion. 
On said mold plates 204A, 204B there are mounted coils C1-C4 for generating 
magnetic flux as shown in FIG. 13D. 
A mask member 206 has an aperture 206a for covering the surface of the 
non-magnetic portions 204a.sub.2, 204a.sub.3 of the mold plate 204A and 
exposing areas where the circuit pattern B3 of the cavity 204C is to be 
formed. Said mask member 206 is formed with a material same as that of 
said non-magnetic portion of the mold plate 204A, and is fixed to the 
non-magnetic portions 204a.sub.2, 204a.sub.3 with suitable means. 
After the mask member 206 is fixed in the cavity of the mold plate 204A, a 
circuit patterning material 210 composed of magnetic powder is coated in 
said cavity, bearing said mask member 206, by means of a painting machine 
208 as shown in FIG. 13B. 
Said circuit patterning material 210 is prepared by mixing 90 wt. % of 
nickel powder of an aveparticle size of 2-3 .mu.m and 10 wt. % of acrylic 
resin powder in the thermally fused state thereof, and crushing the cooled 
mixture to powder with an average particle size of 30 .mu.m. The nickel 
powder employed in said powder 210 can be composed of a product called 
Type 225 supplied by Inco Limited Japan, and the acrylic resin powder can 
be composed of a product called Finedic A224S supplied by Dai-Nippon Ink 
Chemical Industries Co. The powder thus obtained is emitted in negatively 
charged state from the painting machine 208 supplied with a voltage of -70 
kV onto the mask 206, whereby, as shown in FIG. 13B, the powder is 
attracted, by the electrostatic force, to the internal face of the cavity 
of the mold plate 204A. After said powder coating, the mask 206 is removed 
to obtain a circuit pattern formed by said powder 210 on the surface of 
the magnetic portion 204a.sub.1. Subsequently the movable mold plate 204B 
is closed, and the exciting coils are energized, whereby a magnetic 
circuit is formed through the magnetic portion 204a.sub.1 of the mold 
plate 204A, the magnetic portion 204b.sub.1 of the mold plate 204B, and 
the powder 210, thus enhancing the adhesion of powder to the mold plate. 
The magnetic force of said magnetic circuit was for example obtained by 
supplying a current of 60 A in a coil of 346 turns. 
Subsequently polystyrene resin fused at 200.degree. C. was injected, from 
an unrepresented injecting cylinder, with a pressure of 340 kg/cm.sup.2 
into said cavity. The cavity of the mold plates 4A, 4B are so formed as to 
obtain a projection 201A in the molded article as shown in FIG. 13A. When 
said resin is injected into the cavity with the above-mentioned pressure, 
the powder 210 is maintained on the predetermined position of the magnetic 
portion 204a.sub.1 of the mold plate 204A by means of the aforementioned 
magnetic and electrostatic force, and the injected resin fills the cavity 
in such a manner that the circuit pattern formed by said powder 210 is 
embedded in said resin. 
The molded article 201 is taken out of the mold after said resin injection 
and cooling. As shown in FIG. 13E, the obtained molded article 201 is 
provided with a circuit pattern B3 composed of the powder 210 and 
positioned over the projection 201a, a lateral portions 201a.sub.1 thereof 
and an internal flat portion of the molded article. 
The circuit pattern composed of a copper foil on the board 202a is pressed 
against the circuit pattern B3 on the end face of the projection 201a of 
the molded article, and said board 202a is fixed with a screw as shown in 
FIG. 12. Also the circuit pattern composed of a copper foil on the board 
202b is pressed against the other end of the circuit pattern B3 of the 
molded article 201, and said board 202b is fixed with an unrepresented 
screw. 
In the above-explained structure, the circuit boards 202a, 202b are 
mutually connected electrically by the circuit pattern B3 integrally 
formed on the internal surface of the molded article. 
It is thus rendered possible to eliminate rigid or flexible circuit boards, 
lead wires or bound wires for connecting different circuit blocks and to 
obtain a simple electric circuit assembly, by forming a projecting portion 
on a body or a cover of an electric equipment involving electric circuits, 
integrally forming a circuit pattern containing magnetic powder 
simultaneously with the molding of said projection in a same mold, and 
electrically connecting said circuit pattern on said projection on with a 
circuit pattern on a circuit board fixed to said body or cover. 
It is also rendered possible to reduce the number of circuit boards or the 
size thereof, and to resolve the difficulty in making long connections. 
Now reference is made to FIGS. 14 to 16 for explaining a second embodiment 
of the electric circuit assembly in which a projection is molded with a 
resin material on the internal surface of a body or a cover of an electric 
equipment involving electric circuits or an intermediate member thereof, a 
terminal pattern containing magnetic powder is integrally molded on the 
surface of said projection simultaneously with the molding or said body, 
cover or intermediate member in a same mold, and a circuit connector is 
connected to said projection bearing said terminal pattern. 
FIGS. 14 and 15 illustrate this embodiment wherein 301 is a cover of the 
electric equipment, and 302 is a body or a cover thereof. 
Also there are shown a projection 301A formed inside the cover 301; a 
circuit board B1 provided with a first circuit; and a circuit pattern B3, 
corresponding to the circuit B3 shown in FIG. 1, of which an end is 
positioned on a flat plane inside the cover 301 and is electrically 
connected by pressure contact with an unrepresented circuit pattern of 
said circuit board B1, and of which the other end is extended from the 
base of said projection 301A inside the cover through the top of said 
projection to the base at the other side of said projection. 
There are further shown another projection 302A formed on the body 302; a 
circuit board B2 corresponding to the circuit block B2 shown in FIG. 1; 
and a circuit pattern B4, formed on the internal surface of the body 302, 
having an end positioned on a flat plane of the body and maintained in 
pressure contact with the board B2 for electrical connection with the 
circuit thereon and the other end extended from the base portion of said 
projection through the top of said projection to the base portion at the 
other side thereof. FIG. 15 is a perspective view showing the interior of 
the cover 301. The pattern B3 is formed on both perpendicular faces of the 
projection 301A, which constitutes, together with said pattern B3, a male 
connector for circuit connection. 
In FIGS. 14 and 15, a circuit connector 303 is provided with receptacles 
303A, 303B for receiving the projections 301A, 302A of said cover or body 
and is so constructed as to electrically connect the circuit pattern B3 of 
the cover and the circuit pattern B4 of the body when said projections are 
inserted into said receptacles of the connector 303. 
Now reference is made to FIGS. 16A to 16E for explaining a process for 
forming the pattern B3 inside the cover shown in FIGS. 14 and 15. There 
are shown a fixed mold plate 304A and a movable mold plate 304B. The fixed 
mold plate 304A is composed of a magnetic mold plate 304a.sub.1, 
corresponding to the area of circuit pattern B3 shown in FIG. 14, and 
non-magnetic mold plates 304a.sub.2, 304a.sub.3. The movable mold plate 
304B is composed of a magnetic mold plate 304b.sub.1, corresponding to the 
area of the pattern B3, and non-magnetic mold plates 304b.sub.2, 
304b.sub.3. Said movable and fixed mold plates form a cavity for molding 
said cover 301 when said mold plates are mutually tightened. 
The molding process in the embodiment shown in FIGS. 14 to 16E, and the 
patterning material employed therein are same as those in the embodiment 
shown in FIGS. 12 to 13 and need not therefore be explained further. 
Also the body 302 shown in FIG. 14 and the circuit pattern thereon can be 
integrally molded with the same apparatus and process for molding the 
cover shown in FIGS. 16A to 16E. The moldings of the body 302 and the 
cover 301 are different only in the form of cavity due to the difference 
in the form of the body and the cover, and the integral formation of the 
circuit pattern B4 and B3 can be achieved in identical manner. In the 
cover 301 or body 302 formed according to the process shown in FIGS. 16A 
to 16E, the circuit pattern B3 or B4 is formed from the base portion of 
the projection 301A or 302A through the top face of said projection to the 
other base portion thereof, as shown in FIG. 15, integrally with said body 
or cover and simultaneously with the molding thereof. Thus, when the 
projections of the cover 301 and the body 302 are inserted into the 
connector 303, the circuit B1 is electrically connected with the circuit 
B2, through the pattern B3 inside the cover, the connector 303 and the 
pattern B4 inside the body. 
In the embodiment shown in FIGS. 14 and 15 the projections 301A, 302A are 
respectively formed on the cover 301 and the body 302 and are mutually 
connected with the connector 303, but it is also possible to form the 
projection 302A on the body 302 and insert said projection to a connector 
connected to an unrepresented circuit board. 
Furthermore it is possible to employ an intermediate member to be fixed to 
the cover 301 or body 302, instead of said cover or body itself, and to 
integrally form a circuit pattern on said intermediate member in the 
process shown in FIGS. 16A to 16E. 
As explained in the foregoing, the present invention is featured by forming 
a projection with a resin material on the internal surface of a body or a 
cover of an electric equipment involving electric circuits or an 
intermediate member to be fixed to said body or cover and integrally 
forming a terminal pattern containing magnetic powder on the surface of 
said projection simultaneously with the molding of said body, cover or 
intermediate member, and connecting a circuit connector to said projection 
bearing said terminal pattern, thereby reducing the number of circuit 
boards and eliminating complex wires between the cover 301 and the body 
302. 
Also according to the present invention the projection 301A or 302A, 
bearing the terminal pattern B3 or B4 for connecting with the connector, 
is provided in a predetermined position of the cover 301, body 302 or 
intermediate member, so that the position of the connector 303 can also be 
fixed. It is therefore possible to employ automatic assembling process in 
the assembly of the electric equipment. 
FIG. 17 is a partial cross-sectional view of another embodiment of a resin 
molded article serving as a cover, a case, a body or an intermediate 
member of an electric equipment involving electric circuits, wherein 400 
shows a partial cross section of said molded article. Mutually neighboring 
faces 400A, 400B of said article 400 are connected with a curved face 
400C, and a circuit pattern 500 is formed over said neighboring faces 
400A, 400B and said curved face 400C. Circuit blocks B1, B2 shown in FIG. 
1 are positioned at respective ends of said circuit pattern 500 and are 
electrically connected thereto. 
FIG. 18 is a schematic cross-sectional view of an apparatus for producing 
the resin molded article shown in FIG. 17, and FIGS. 19A to 19E illustrate 
a process of molding said article. 
FIG. 18 shows a magnetic circuit formed by a mold 404 and an exciting coil 
403 mounted on a molding machine. The mold 404 is composed of a movable 
mold plate 405 and a fixed mold plate 406, and a pattern forming portion 
on the surface of a cavity 407 is composed of magnetic portions 405a, 406a 
for example of carbon steel, while other portion is composed of 
non-magnetic portions 405b, 406b for example of SUS 303. A platen 401 and 
a tie bar 402 of the molding machine are composed of magnetic materials 
such as carbon steel. When energized, said coil 403 generates a magnetic 
flux 412 as indicated by arrows, thereby generating a magnetic force on 
the surface of the magnetic portions 405a, 406a of the cavity 407 and 
depositing magnetic powder 409 to the cavity surface by magnetic 
attraction. 
In the mold structure shown in FIG. 18, corner portions 405a', 406a' of the 
mold plates 405a, 406a constituting the cavity 407 are formed as curved 
surfaces of radii R1, R2. Said radii R1 and R2 are preferably selected to 
satisfy a relation R2-R1=t, wherein t is the thickness of the resin molded 
article 400. Also preferably the thickness of the flat portions 400A, 400B 
of the resin molded article is selected equal to that of the curved 
portion 400C. 
FIGS. 19A to 19E show a process for producing the resin molded article of 
the present embodiment. 
At first the movable mold plate 405 is opened as shown in FIG. 19A, and a 
mask 408 is placed on the cavity face of the non-magnetic portion 405b, 
thus exposing the magnetic portion 405a on which the magnetic powder is to 
be deposited. Said mask 408 can be formed for example of metal, rubber or 
plastics and is fixed to the movable mold plate 405 by suitable means. 
Then, as shown in FIG. 19B, the exposed portion of the cavity face and the 
mask 408 are coated with the magnetic powder 407 by means of an 
electrostatic painting machine 410. Said magnetic powder is composed of a 
ferromagnetic conductive material containing a binder component, and can 
be obtained, for example, by mixing 90 wt. % of nickel powder of an 
average particle size of 2-3 .mu.m and 10 wt. % of acrylic resin powder as 
the binder component, in the thermally fused state of the binder 
component, and crushing the cooled mixture to powder with an average 
particle size of 30 .mu.m. For said nickel powder there can be employed a 
product called Type 255 supplied by Inco Limited Japan, and for said 
acrylic resin there can be employed a product called Finedic A224S 
supplied by Dai Nippon Ink Chemical Industries Co. When said magnetic 
powder 408, charged negatively with a voltage of -70 kV, is coated with 
the electrostatic painting machine 10 onto the grounded mold, said powder 
is deposited on the magnetic portion 405a and the mask 408 by the 
electrostatic force between the powder and the mold. 
Then the mask 408 is removed from the movable mold plate 405 to obtain a 
pattern of said magnetic powder 409 solely on the surface of the magnetic 
portion 405a in the cavity 407 as shown in FIG. 19C. 
Subsequently, as shown in FIG. 19D, the mold 404 is closed and the coil 403 
is energized, whereby a magnetic force is generated on the surface of the 
magnetic portion 405a, thus firmly maintaining the already deposited 
magnetic powder 409 by magnetic attraction. Then a resin material is 
injected in the cavity. Said resin fills the cavity in such a manner that 
the magnetic powder is embedded in the injected resin, while said powder 
is maintained in the predetermined position in the cavity by the magnetic 
and electrostatic attractive force. The binder component, such as acrylic 
resin, contained in the magnetic powder 409 is softened or fused by the 
high temperature and high pressure of the injected resin 411, and 
solidifies simultaneously with the cooling of said resin, thus realizing 
very strong adhesion between the binder component and the molded resin. 
FIG. 19E shows the molded article taken out of the mold after cooling. The 
pattern of the magnetic powder 409 formed on the cavity face of the mold 
prior to molding operation is transferred as a circuit pattern 413 
embedded on the surface of the injected resin 411 constituting the molded 
article. 
As an example a coil 403 of 346 turns was energized with a current of 60 A, 
and polystyrene resin of 200.degree. C. was injected from an injecting 
cylinder with a pressure of 340 kg/cm.sup.2 into the cavity. There was 
obtained a molded article bearing a circuit pattern of a surface 
resistivity of 1.0 .OMEGA./cm.sup.2 formed by the transfer of said 
magnetic powder to a predetermined position. 
In this manner the circuit pattern 500 can be formed simultaneously with 
the molding of the article 400. Integrated circuits constituting the 
circuit blocks B1, B2 are respectively connected to the end portions of 
said circuit pattern 500. 
As explained in the foregoing, the present invention allows to eliminate 
the conventional flexible circuit board and to simplify the assembling 
operation by placing circuit blocks B1, B2 on mutually neighboring flat 
portions of a resin molded article and electrically connecting said 
circuit blocks with a circuit pattern 500 formed simultaneously with the 
molding of said resin molded article. 
Also according to the present invention said neighboring flat portions of 
the resin molded article are connected with a curved portion, thereby 
avoiding insufficient adhesion of the magnetic powder in such connecting 
portion and thus improving the reliability of the circuit pattern 500. 
Furthermore, said curved portion 400C may be replaced by a slanted planar 
portion 400c' shown in FIG. 20.