ELECTRONIC CONTROL DEVICE AND MANUFACTURING METHOD FOR THE SAME
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic control device, which includes a card edge connector having contact terminals arranged at an end portion of an electronic circuit board to be connected to terminals of an external connector, and to a manufacturing method for the electronic control device.
2. Description of the Related Art
Hitherto, there has been known an electronic control device which includes an electronic circuit board, a connector fixed to the electronic circuit board, a casing configured to receive the electronic circuit board and the connector, and a resin portion filled into the casing (for example, see Japanese Patent No. 4471993).
However, when the card edge connector is employed in place of the connector, and the resin portion filled into the casing is omitted for the purpose of cost reduction, a holding force that is a force exerted by the casing to hold the electronic circuit board is lost. There has been a problem in that such loss of the holding force causes the electronic circuit board to project from the casing when terminals of the external connector are removed from the card edge connector.

SUMMARY OF THE INVENTION
The present invention has been made to solve the problem described above, and has an object to provide an electronic control device, which is capable of reducing cost and obtaining a holding force exerted by a casing to hold an electronic circuit board, and a manufacturing method for the electronic control device.
According to one embodiment of the present invention, there is provided an electronic control device, including: an electronic circuit board; and a casing configured to receive the electronic circuit board, the electronic circuit board having an engaged portion, the engaged portion being one of a penetrating hole extending in a thickness direction of the electronic circuit board and a cutout portion extending from an end surface of the electronic circuit board in a width direction of the electronic circuit board toward an inner side of the electronic circuit board in the width direction, the engaged portion receiving a part of the casing inserted into the engaged portion.
In the electronic control device according to the present invention, a part of the casing is inserted into the engaged portion formed in the electronic circuit board. Therefore, even when the card edge connector is employed in place of the connector, and the resin portion filled into the casing is omitted, the holding force exerted by the casing to hold the electronic circuit board can be obtained. Thus, the cost of the electronic control device can be reduced, and the casing can hold the electronic circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view for illustrating an electronic control device according to a first embodiment of the present invention.
FIG. 2 is a plan view for illustrating the electronic control device of FIG. 1.
FIG. 3 is a front view for illustrating the electronic control device of FIG. 1.
FIG. 4 is a plan view for illustrating an electronic circuit board of FIG. 1.
FIG. 5 is a sectional view taken along the line V-V of FIG. 2 and viewed from a direction indicated by the arrows.
FIG. 6 is an enlarged view for illustrating the portion B of FIG. 5.
FIG. 7 is a view for illustrating a state before heat-caulked portions of FIG. 6 are formed.
FIG. 8 is a perspective view for illustrating an electronic control device according to a second embodiment of the present invention.
FIG. 9 is a plan view for illustrating an electronic circuit board of FIG. 8.
FIG. 10 is a plan view for illustrating a casing of FIG. 8.
FIG. 11 is a side view for illustrating the casing of FIG. 8.

FIG. 12 is a sectional view taken along the line XII-XII of FIG. 11 and viewed from a direction indicated by the arrows.
FIG. 13 is an enlarged view for illustrating the portion C of FIG. 12.
FIG. 14 is a view for illustrating a state before heat-caulked portions of FIG. 13 are formed.
FIG. 15 is a view for illustrating a state in which a female connector on a vehicle side is fitted to the electronic control device of FIG. 8.
DESCRIPTION OF THE EMBODIMENTS
Now, an electronic control device according to each of embodiments of the present invention is described with reference to the drawings.
First Embodiment
FIG. 1 is a perspective view for illustrating an electronic control device according to a first embodiment of the present invention. An electronic control device 1A includes an electronic circuit board 2A and a casing 3A configured to receive the electronic circuit board 2A.
The electronic circuit board 2A has a plurality of electronic components (not shown) mounted thereto. The electronic circuit board 2A is a wiring board configured to electrically connect the plurality of electronic components. The electronic circuit board 2A has an electronic circuit of the electronic control device 1A.

The casing 3A receives the electronic circuit board 2A inserted thereinto. The casing 3A has an opening portion 301 which allows the electronic circuit board 2A to pass therethrough when the electronic circuit board 2A is inserted into the casing 3A. The opening portion 301 is formed at a rear end portion of the casing 3A in an insertion direction. In this example, the insertion direction is a direction in which the electronic circuit board 2A is inserted into the casing 3A, and corresponds to the direction of the arrow A of FIG. 1.
The casing 3A includes a pair of first walls 302, a pair of second walls 303, and a third wall 304. The first walls 302 are opposed to a top surface and a back surface of the electronic circuit board 2A. The second walls 303 are opposed to both side surfaces of the electronic circuit board 2A in a width direction. The third wall 304 is opposed to a front end surface of the electronic circuit board 2A in the insertion direction.
Heat-caulked portions 305 are formed at a front end portion of the first wall 302 in the insertion direction. The heat-caulked portions 305 are arranged at both end portions of the first wall 302 in the width direction. Further, the heat-caulked portions 305 are arranged in each of the pair of first walls 302. The heat-caulked portions 305 are formed through use of heat-caulking jigs 4 described later. In this example, the width direction is a direction orthogonal to the insertion direction of the electronic circuit board 2A and is a direction orthogonal to a thickness

direction of the electronic circuit board 2A.
Recessed portions 306 are formed at the front end portion of the first wall 302 in the insertion direction. The recessed portions 306 are arranged at both end portions of the first wall 302 in the width direction. Further, the recessed portions 306 are arranged in each of the pair of first walls 302. The heat-caulked portions 305 are formed in the recessed portions 306.
The electronic circuit board 2A is held by the heat-caulked portion 305 in the casing 3A. The rear end portion of the casing 3A in the insertion direction, in other words, the end portion of the casing 3A on the opening portion 301 side is fitted to a female connector being an external connector on a vehicle side. In other words, the rear end portion of the casing 3A in the insertion direction is fitted to a female connector on a harness side. Through fitting of the electronic circuit board 2A to the female connector on the vehicle side, the electronic control device 1A is electrically connected to components on the vehicle side. The components on the vehicle side may be, for example, a sensor and an actuator.
FIG. 2 is a plan view for illustrating the electronic control device 1A of FIG. 1, and FIG. 3 is a front view for illustrating the electronic control device 1A of FIG. 1. The casing 3A is made of thermoplastic resin. The thermoplastic resin may be, for example, PBT, PPS, or PA66. The casing 3A has a cylindrical shape with the opening portion 301 formed in the rear end portion in the

insertion direction.
The casing 3A includes rails 307 configured to guide the electronic circuit board 2A. The rails 307 are arranged on inner surfaces of the pair of second walls 303. Further, the rails 307 are arranged at both end portions of the second wall 303 in a height direction.
FIG. 4 is a plan view for illustrating the electronic circuit board 2A of FIG. 1. A plurality of contact terminals 21 are formed at the rear end portion of the electronic circuit board 2A in the insertion direction. Through fitting of the female connector on the vehicle side and the opening portion 301 of the casing 3A to each other, the contact terminals 21 and terminals of the female connector on the vehicle side are brought into contact with each other, with the result that the contact terminals 21 and the terminals of the female connector on the vehicle side are electrically connected to each other.
At the front end portion of the electronic circuit board 2A in the insertion direction, there are formed penetrating holes 22 being engaged portions penetrating through the electronic circuit board 2A in the thickness direction. The penetrating holes 22 are formed in both end portions of the electronic circuit board 2A in the width direction. In this example, each penetrating hole 22 has a circular shape. The shape of the penetrating hole 22 is not limited to the circular shape, and may be other shapes.
The penetrating holes 22 are arranged so that, when the

electronic circuit board 2A is received in the casing 3A, the penetrating holes 22 and the heat-caulked portions 305 overlap each other in the thickness direction of the electronic circuit board 2A. A space between the electronic circuit board 2A and each of the recessed portions 306 is narrower than a space between a portion of the casing 3A, which is other than the recessed portions 306, and the electronic circuit board 2A. Therefore, no electronic component is arranged at portions of the electronic circuit board 2A, which overlap the recessed portions 306 in the thickness direction of the electronic circuit board 2A. In other words, no electronic component is arranged at portions of the electronic circuit board 2A, which are opposed to the recessed portions 306. FIG. 5 is a sectional view taken along the line V-V of FIG. 2 and viewed from a direction indicated by the arrows. FIG. 6 is an enlarged view for illustrating the portion B of FIG. 5. FIG. 7 is a view for illustrating a state before the heat-caulked portions 305 of FIG. 6 are formed. The casing 3A includes a plurality of protrusions 308 configured to position the electronic circuit board 2A inserted into the casing 3A. The protrusions 308 are formed on inner surfaces of the recessed portions 306 in the pair of first walls 302 and on inner surfaces of the pair of second walls 303. When the electronic circuit board 2A is inserted into the opening portion 301, and the electronic circuit board 2A is received in the casing 3A along the rails 307, the electronic circuit board 2A and the protrusions 308 are brought into contact with each other,

and distal end portions of the protrusions 308 are squeezed. With this action, a positional relationship of the electronic circuit board 2A with respect to the casing 3A in the thickness direction and in the width direction is determined.
In order to achieve the configuration of causing the distal end portions of the protrusions 308 to be squeezed by the electronic circuit board 2A, a dimension between the pair of protrusions 308 arranged on the inner surfaces of the recessed portions 306 of the pair of first walls 302 is set smaller than a dimension of the electronic circuit board 2A in the thickness direction. Further, a dimension between the pair of protrusions 308 arranged on the inner surfaces of the pair of second walls 303 is set smaller than a dimension of the electronic circuit board 2A in the width direction. For the purpose of improving the positional accuracy, it is desired that the protrusions 308 be provided at three or more locations.
A positional relationship of the electronic circuit board 2A with respect to the casing 3A in the insertion direction is determined by bringing the front end portion of the electronic circuit board 2A in the insertion direction into contact with the third wall 304 of the casing 3A.
Next, description is made of a heat-caulked portion forming step of forming the heat-caulked portions 305 configured to prevent board separation, which is separation of the electronic circuit board 2A from the casing 3A. Before the heat-caulked portion forming step, at portions of the casing 3A at which the heat-caulked

portions 305 are to be formed, there are formed protruding portions 309 protruding outward from the recessed portions 306 in the thickness direction. In this example, each protruding portion 309 has a cylindrical shape. The shape of each protruding portion 309 is not limited to the cylindrical shape, and may be other shapes. Through formation of the protruding portions 309 at the recessed portions 306, there are formed thick portions 310 at portions of the casing 3A, which are opposed to the penetrating holes 22 before the heat-caulked portion forming step.
When the heat-caulked portion forming step is performed, a pair of heat-caulking jigs 4 are used. In this example, each heat-caulking jig 4 has a columnar shape. With the protruding portions 309 serving as marks, the heat-caulking jigs 4 are set so that the casing 3A is sandwiched by the pair of heat-caulking jigs 4 in the thickness direction. Then, the pair of heat-caulking jigs 4 are moved in directions of causing the pair of heat-caulking jigs 4 to approach each other. With this action, heat and pressure are applied from the pair of heat-caulking jigs 4 to the thick portions 310 of the casing 3A. The casing 3A is made of thermoplastic resin. Therefore, the thick portions 310 are plasticized and deformed by the heat applied from the heat-caulking jigs 4. Further, the heat-caulked portions 305 are formed in the casing 3A by the pressure applied from the heat-caulking jigs 4. At this time, a part of the casing 3A is inserted into the penetrating holes 22. In other words, the casing 3A has engaging portions 311

inserted into the penetrating hole 22. The engaging portions 311 are arranged on the inner surfaces of the first walls 302. With this action, the electronic circuit board 2A is fixed to the casing 3A.
The portions of the casing 3A at which the heat-caulked portions 305 are formed are the recessed portions 306. This is because, for the heat-caulked portion forming step, when the distance between the penetrating hole 22 and each portion of the casing 3A at which the heat-caulked portion 305 is formed is not set small, the casing 3A may be deformed before the plasticized thermoplastic resin enters the penetrating hole 22, with the result that breakage of the casing 3A may occur.
At portions of the casing 3A at which the heat-caulked portions 305 are formed, there are formed the thick portions 310. This is for the purpose of securing the mechanical strength of the casing 3A even after deformation of the casing 3A, thereby preventing loss of a waterproof property due to the breakage of the casing 3A. However, there is a fear in that the formation of the thick portions 310 degrades the processability in the heat-caulked portion forming step. Therefore, when a radial dimension of the heat-caulking jig 4 is φA, and a radial dimension of the thick portion 310 is φB, the radial dimension φA is set equal to or larger by about several millimeters than the radial dimension φB, that is, the radial dimensions are set so as to satisfy φA≥φB, thereby suppressing application of heat and pressure to portions

of the casing 3A other than the portions at which the heat-caulked portions 305 are formed. In this case, heat can be applied to the entirety of the thick portion 310, thereby being capable of processing the thick portions 310 without causing non-squeezed portions. Further, in this case, high positional accuracy for the heat-caulking jigs 4 is not required, and hence simple processing can be achieved.
After the heat-caulked portions 305 are formed by deforming the thick portions 310 through use of the heat-caulking jigs 4, the heat-caulking jigs 4 are cooled and separated from the casing 3A. When the heat-caulking jigs 4 are separated from the casing 3A before being cooled, the heat-caulking jigs 4 are separated from the casing 3A while the plasticized thermoplastic resin adheres to the heat-caulking jigs 4, with the result that deformation and defects may occur in the casing 3A.
As described above, in the electronic control device 1A according to the first embodiment of the present invention, a part of the casing 3A is inserted into the penetrating holes 22 formed in the electronic circuit board 2A. Therefore, even when the card edge connector is employed in place of the connector, and the resin portion filled into the casing 3A is omitted, the holding force exerted by the casing 3A to hold the electronic circuit board 2A can be obtained. Thus, cost of the electronic control device 1A can be reduced, and the casing 3A can hold the electronic circuit board 2A.

Further, with the manufacturing method for the electronic control device 1A according to the first embodiment of the present invention, the heat-caulked portion forming step of partially applying the heat and pressure to the casing 3A is performed, to thereby fix the electronic circuit board 2A to the casing 3A. Thus, separation of the electronic circuit board 2A from the casing 3A is prevented. With this method, separation of the electronic circuit board 2A can be prevented at low cost without use of additional members such as adhesives. Further, as compared to a fixing method using a structure of press-fitting the electronic circuit board 2A into the casing 3A, or a fixing method using an adhesive, the present invention achieves a larger holding force exerted by the casing 3A to hold the electronic circuit board 2A, thereby improving the durability of the connector against insertion and removal. Further, the number of fixed portions between the casing 3A and the electronic circuit board 2A increases, thereby being capable of suppressing wobbling of the electronic circuit board 2A with respect to the casing 3A. In the case of the card edge connector, when significant wobbling occurs, friction may occur between the contact terminals 21 and the terminals of the female connector on the vehicle side, and the contact resistance between the terminals may increase. Further, there is a fear in that disconnection may occur between the terminals. Thus, suppression of wobbling may improve the durability against vibration. Further, when the protruding portions 309 are pressed

with the heat-caulking jigs 4, caulking marks 312 are formed, thereby being capable of recognizing omission of the heat-caulked portion forming step at a glance.
Further, with the manufacturing method for the electronic control device 1A, the thick portions 310 are formed at portions of the casing 3A, which are opposed to the penetrating holes 22 before the heat-caulked portion forming step. In the heat-caulked portion forming step, the thick portions 310 are heated to be deformed, and parts of the casing 3A are inserted into the penetrating holes 22, thereby being capable of suppressing occurrence of the breakage of the casing 3A.
Further, with the manufacturing method for the electronic control device 1A, the radial dimension of each thick portion 310 is smaller than the radial dimension of each heat-caulking jig 4, thereby being capable of suppressing occurrence of non-squeezed portions of the thick portions 310.
In the above-mentioned first embodiment, description is made of the configuration in which the portion of the casing 3A at which the heat-caulked portions 305 are formed is the front end portion of the casing 3A in the insertion direction. However, the heat-caulked portions 305 may be formed at the rear end portion of the casing 3A in the insertion direction, that is, a portion close to the contact terminals 21. As the positions of the heat-caulked portions 305 approach the contact terminals 21, wobbling between the contact terminals 21 and the terminals of the

female connector on the vehicle side can further be suppressed, thereby being capable of improving the connection reliability, that is, the durability of the contact terminals 21 against vibration.
Second Embodiment
FIG. 8 is a perspective view for illustrating an electronic control device according to a second embodiment of the present invention. An electronic control device 1B includes an electronic circuit board 2B and a casing 3B configured to receive the electronic circuit board 2B. In the pair of second walls 303 of the casing 3B, there are formed the heat-caulked portions 305. The heat-caulked portions 305 are arranged at the rear end portion of the casing 3B in the insertion direction.
FIG. 9 is a plan view for illustrating the electronic circuit board 2B of FIG. 8. In both side surfaces of the electronic circuit board 2B in the width direction, there are formed cutout portions 23 being engaged portions. The cutout portions 23 are arranged so as to extend from end surfaces of the electronic circuit board 2B in the width direction toward an inner side in the width direction. The cutout portions 23 are arranged at the rear end portion in the insertion direction. The cutout portions 23 are arranged so that the cutout portions 23 and the heat-caulked portions 305 are opposed to each other in the width direction when the electronic circuit board 2B is received in the casing 3B. The electronic circuit board 2B has no penetrating hole 22, unlike the first embodiment.
FIG. 10 is a plan view for illustrating the casing 3B of FIG.

8, and FIG. 11 is a side view for illustrating the casing 3B of FIG. 8. The casing 3B is made of thermoplastic resin. Further, at the rear end portion of the casing 3B in the insertion direction, there is formed the opening portion 301. The casing 3B has a cylindrical shape. The casing 3B has no recessed portion 306, unlike the first embodiment.
FIG. 12 is a sectional view taken along the line XII-XII of FIG. 11 and viewed from a direction indicated by the arrows. FIG. 13 is an enlarged view for illustrating the portion C of FIG. 12. FIG. 14 is a view for illustrating a state before the heat-caulked portions 305 of FIG. 13 are formed. The casing 3B has engaging portions 311 protruding from the second walls 303 toward the inner side in the width direction. The engaging portions 311 are arranged so as to be opposed to the cutout portions 23 of the electronic circuit board 2B received in the casing 3B. The engaging portions 311 are inserted into the cutout portions 23. With this configuration, the board separation that is the separation of the electronic circuit board 2B from the casing 3B is prevented.
When the electronic circuit board 2B passes through the opening portion 301 and is inserted until the front end portion of the electronic circuit board 2B in the insertion direction is brought into abutment against the third wall 304 of the casing 3B, and is received in the casing 3B, the electronic circuit board 2B is positioned with respect to the casing 3B. When the electronic circuit board 2B is positioned with respect to the casing 3B, the

cutout portions 23 are opposed to the portions of the casing 3B at which the heat-caulked portions 305 are formed.
The opening portion 301 of the casing 3B has a surplus dimension of about several millimeters in the width direction of the electronic circuit board 2B so as to allow the electronic circuit board 2B to be easily inserted. This surplus dimension may cause wobbling of the electronic circuit board 2B when vibration is applied to the electronic control device 1B, with the result that friction may occur in contact surfaces between the terminals of the female connector on the vehicle side and the contact terminals 21. When the friction occurs in the contact surfaces between the terminals of the female connector on the vehicle side and the contact terminals 21, the contact resistance between the terminals of the female connector on the vehicle side and the contact terminals 21 increases, with the result that disconnection may occur between the terminals of the female connector on the vehicle side and the contact terminals 21. According to the present invention, the wobbling of the casing 3B and the electronic circuit board 2B can be reduced, thereby being capable of improving the resistance against vibration. Further, in the second embodiment, the electronic circuit board 2B is fixed to the casing 3B near the contact terminals 21, and hence the effect of the resistance against vibration is higher as compared to the first embodiment.
As compared to the first embodiment, the electronic control device 1B according to the second embodiment is capable of reducing

mounting-prohibited regions for electronic components. In the first embodiment, the penetrating holes 22 are formed in the electronic circuit board 2A, with the result that mounting-allowed regions for electronic components are reduced by the area of the penetrating holes 22, and the mounting-prohibited regions increase. Further, the recessed portions 306 are formed around the penetrating holes 22 in the electronic control device 1A according to the first embodiment. Therefore, the dimension between the electronic circuit board 2A and each recessed portion 306 is small, with the result that electronic components cannot be mounted to portions opposed to the recessed portions 306. That is, in addition to the portions of the electronic circuit board 2A, at which the penetrating holes 22 are arranged, the portions of the electronic circuit board 2A, which are opposed to the recessed portions 306, also become the mounting-prohibited regions. Meanwhile, in the electronic control device 1B according to the second embodiment, the cutout portions 23 are formed at the end portions of the electronic circuit board 2B in the width direction. The regions of about 2 mm from the end surfaces of the electronic circuit board 2B in the width direction are regions of the casing 3B in contact with the rails 307, and hence are mounting-prohibited regions in which electronic components cannot be mounted as in the first embodiment. The cutout portions 23 are formed at the end portions of the electronic circuit board 2B in the width direction, and the heat-caulked portion forming step is performed. That is, the

heat-caulked portion forming step is performed with respect to the mounting-prohibited regions. Therefore, as compared to the first embodiment, the electronic control device 1B according to the second embodiment can significantly reduce the mounting-prohibited regions. Other configurations are the same as those of the first embodiment.
Next, description is made of a heat-caulked portion forming step of forming the heat-caulked portions 305 configured to prevent board separation, which is separation of the electronic circuit board 2B from the casing 3B. Before the heat-caulked portion forming step, at the portions of the casing 3B at which the heat-caulked portions 305 are to be formed, there are formed the protruding portions 309 protruding outward from the second walls 303 in the width direction. In this example, each protruding portion 309 has a cylindrical shape. The shape of each protruding portion 309 is not limited to the cylindrical shape, and may be other shapes. Through formation of the protruding portions 309 at the second walls 303, there are formed the thick portions 310 at portions of the casing 3B, which are opposed to the cutout portions 23 before the heat-caulked portion forming step.
When the heat-caulked portion forming step is performed, the heat-caulking jigs 4 are used. In this example, each heat-caulking jig 4 has a columnar shape. With the protruding portions 309 serving as marks, the heat-caulking jigs 4 are set so that the heat-caulking jigs 4 are opposed to the casing 3B in the width direction. Then,

the heat-caulking jigs 4 are moved in directions of causing the heat-caulking jigs 4 to approach the casing 3B in the width direction. With this action, heat and pressure are applied from the pair of heat-caulking jigs 4 to the thick portions 310 of the casing 3B. The casing 3B is made of thermoplastic resin. Therefore, the thick portions 310 are plasticized and deformed by the heat applied from the heat-caulking jigs 4. Further, the heat-caulked portions 305 are formed in the casing 3B by the pressure applied from the heat-caulking jigs 4. At this time, a part of the casing 3B is inserted into the cutout portions 23. In other words, the casing 3B has the engaging portions 311 inserted into the cutout portions 23. The engaging portions 311 are arranged on the inner surfaces of the second walls 303. With this action, the electronic circuit board 2B is fixed to the casing 3B.
At portions of the casing 3B at which the heat-caulked portions 305 are formed, there are formed the thick portions 310. This is for the purpose of securing the mechanical strength of the casing 3B even after deformation of the casing 3B, thereby preventing loss of a waterproof property due to the breakage of the casing 3B. However, there is a fear in that the formation of the thick portions 310 degrades the processability in the heat-caulked portion forming step. Therefore, when the radial dimension of the heat-caulking jig 4 is φA, and the radial dimension of the thick portion 310 is φB, the radial dimension φA is set equal to or larger by about several millimeters than the radial dimension

φB, that is, the radial dimensions are set so as to satisfy φA≥φB. Thus, application of heat and pressure to portions of the casing 3B other than the portions at which the heat-caulked portions 305 are formed is suppressed. In this case, heat can be applied to the entirety of the thick portion 310, thereby being capable of processing the thick portions 310 without causing non-squeezed portions. Further, in this case, high positional accuracy for the heat-caulking jigs 4 is not required, and hence simple processing can be achieved.
As described above, with the manufacturing method for the electronic control device 1B according to the second embodiment of the present invention, the heat-caulked portion forming step of forming the engaging portions 311 through use of the heat-caulking jigs 4 and inserting the engaging portion 311 into the cutout portions 23 is performed. As a result, the engaging portions 311 are inserted into the cutout portions 23, and the electronic circuit board 2B is prevented from being separated from the casing 3B. With this method, disassembly of the electronic control device 1B is prevented. Further, there is no need to use additional members such as an adhesive, and the prevention of the separation can be achieved only with thermal processing, thereby enabling manufacture at low cost. Further, the caulking marks 312 remain on the casing 3B, thereby being capable of recognizing omission of the heat-caulked portion forming step at a glance. Further, as compared to the method using an adhesive or the method

using the press-fitting structure, the holding force exerted by the casing 3B to hold the electronic circuit board 2B is larger. Therefore, even in the case of the card edge connector having a large separating force, the electronic circuit board 2B is less liable to be separated, and the durability against insertion and removal is higher.
Further, with the manufacturing method for the electronic control device 1B, the thick portions 310 are formed at portions of the casing 3B which are opposed to the cutout portions 23 before the heat-caulked portion forming step. In the heat-caulked portion forming step, the thick portions 310 are heated to be deformed, and parts of the casing 3B are inserted into the cutout portions 23, thereby being capable of suppressing occurrence of the breakage of the casing 3B.
Further, with the manufacturing method for the electronic control device 1B, the radial dimension of each thick portion 310 is smaller than the radial dimension of each heat-caulking jig 4, thereby being capable of suppressing occurrence of non-squeezed portions of the thick portions 310.
FIG. 15 is a view for illustrating a state in which the female connector on the vehicle side is fitted to the electronic control device 1B of FIG. 8. The electronic control device 1B may further include a seal member 6, which is provided around the casing 3B and is configured to close a gap formed between the casing 3B and a housing 5 of the female connector fitted to the casing 3B.

Alternatively, a seal member may be provided to the female connector, and the electronic control device 1B may have a structure (seal surface) achieving a waterproof property when the casing 3B and the female connector are fitted to each other. When the casing 3B is fitted to the connector, the opening portion 301, which is formed in the casing 3B to allow the electronic circuit board 2B to pass therethrough, is arranged inside the housing 5. The portions of the casing 3B, which are inserted into the cutout portions 23, are arranged on the opening portion 301 side with respect to the seal member 6. With this structure, the heat-caulked portions 305 are protected by the female connector on the vehicle side. In the heat-caulked portion forming step, even when the mechanical strength of the heat-caulked portions 305 is reduced, and damage such as breakage of the casing 3B occurs, the waterproof property of the electronic control device 1B is maintained by the housing 5 of the female connector and by the seal member 6 when the female connector and the electronic control device 1B are fitted to each other.

What is claimed is:
1. An electronic control device, comprising:
an electronic circuit board; and
a casing configured to receive the electronic circuit board, the electronic circuit board having an engaged portion, the engaged portion being one of a penetrating hole extending in a thickness direction of the electronic circuit board and a cutout portion extending from an end surface of the electronic circuit board in a width direction of the electronic circuit board toward an inner side of the electronic circuit board in the width direction, the engaged portion receiving a part of the casing inserted into the engaged portion.
2. An electronic control device according to claim 1, further
comprising one of a seal member and a seal surface, which is provided
around the casing and is configured to close a gap formed between
the casing and a housing of a connector fitted to the casing,
wherein, when the casing is fitted to the connector, an opening portion, which is formed in the casing to allow the electronic circuit board to pass through the casing, is arranged inside the housing, and
wherein the part of the casing, which is inserted into the engaged portion, is arranged on the opening portion side with respect to the one of the seal member and the seal surface.

3. A manufacturing method for an electronic control device,
comprising:
a receiving step of receiving an electronic circuit board, which has an engaged portion being one of a penetrating hole extending in a thickness direction of the electronic circuit board and a cutout portion extending from an end surface of the electronic circuit board in a width direction of the electronic circuit board toward an inner side of the electronic circuit board in the width direction, in a casing made of thermoplastic resin; and
a heat-caulked portion forming step of heating the casing to be deformed and inserting a part of the casing into the engaged portion, after the receiving step, to thereby fix the electronic circuit board to the casing.
4. A manufacturing method for an electronic control device
according to claim 3,
wherein the engaged portion comprises the penetrating hole, wherein a thick portion is formed at a portion of the casing,
which is opposed to the penetrating hole before the heat-caulked
portion forming step, and
wherein, in the heat-caulked portion forming step, the thick
portion is heated to be deformed, and the part of the casing is
inserted into the penetrating hole.

5. A manufacturing method for an electronic control device according to claim 4, wherein a radial dimension of the thick portion is smaller than a radial dimension of a heat-caulking jig configured to heat the thick portion.
6. A manufacturing method for an electronic control device according to claim 3,
wherein the engaged portion comprises the cutout portion, wherein a thick portion is formed at a portion of the casing,
which is opposed to the cutout portion before the heat-caulked
portion forming step, and
wherein, in the heat-caulked portion forming step, the thick
portion is heated to be deformed, and the part of the casing is
inserted into the cutout portion.
7. A manufacturing method for an electronic control device
according to claim 6, wherein a radial dimension of the thick portion
is smaller than a radial dimension of a heat-caulking jig configured
to heat the thick portion.