JP2012209325A - Printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed circuit board, fixed by a screw onto a frame of a device, with a function of testing whether the screw is fixed loosely.SOLUTION: In a printed circuit board, around an opening portion of a screw insertion hole 11c, on an opposite side of a frame 12, provided in an insulation substrate 11a of a printed circuit board to pass through a screw 13, a conductivity check land 11i having a portion in contact, directly or through a washer, with a head of the screw 13 screwed into the frame 12 through the screw insertion hole 11c is provided. After the printed circuit board 11 is fixed onto the frame 12 by the screw, it is examined whether the screw and the conductivity check land are electrically connected, whereby it is possible to check whether the screw is fixed loosely very quick and in an accurate manner.

Description

  The present invention relates to a printed circuit board on which components constituting an electronic circuit are mounted and attached to a frame of a device having the electronic circuit as one of the components, and is particularly incorporated in a rotating electric machine such as a motor or a generator. The present invention relates to a printed circuit board suitable for constituting a controller.

  In general, a printed circuit board constituting an electronic circuit is composed of a printed circuit board in which a wiring pattern is formed on an insulating substrate, and components of the electronic circuit mounted on the printed circuit board. Screwed to the frame of one device. For example, in a brushless DC motor disclosed in Patent Document 1, a printed circuit board on which electronic components constituting a motor controller are mounted is screwed to a frame fixed to the motor housing. In the motor disclosed in Patent Document 1, the printed circuit board is arranged in contact with the frame, and the screw that passes through the screw insertion hole provided in the printed circuit board is screwed into the screw hole provided in the frame. Thus, the printed circuit board is fixed to the frame.

  When the printed circuit board is fixed to the frame by screwing, the screw cannot be tightened to the end due to carelessness of the operator, or there is a mismatch between the length of the screw shaft and the effective length of the screw hole. If the printed circuit board is attached to the frame, the screw may be lifted.

  In this specification, “screw floating” means a washer interposed between the head of the screw and the printed circuit board in a state where the screw is tightened, or between the head of the screw and the printed circuit board as necessary. This means a state in which a gap is formed between the printed circuit board and the printed board (a state where the screw head does not firmly hold the printed board against the frame).

  If the screw is lifted while the screw is tightened, the printed circuit board will not be securely fixed to the frame. This causes problems such as breakage or disconnection of components mounted on the board. In particular, when a printed circuit board is attached to a frame of a device that generates mechanical vibration such as a rotating electrical machine, if the screw is lifted, the above-described problem is remarkably generated.

  FIG. 5 shows a state in which the screw is lifted. In the figure, 1 is a printed circuit board comprising a printed circuit board 1a and electronic components (not shown) mounted on the printed circuit board, 2 is a frame of an apparatus having a pedestal 2d for mounting the printed circuit board, 3 Is a screw having a head portion 3a and a shaft portion 3b and screwed into a screw hole 2e formed in a base portion 2d of the frame 2 through a screw insertion hole 1c penetrating the printed circuit board 1a.

  The screw float is caused by a mistake in operation, and the screw hole 2e is formed so as not to penetrate the frame 2 (in a bag shape), and the length of the shaft portion 3b is longer than the effective length of the female screw portion of the screw hole 2e. This occurs when the long screw 3 is used by mistake or when the effective length of the female screw portion of the screw hole 2e is insufficient due to processing failure. In the illustrated example, since the shaft portion 3b of the screw 3 is too long compared to the effective length of the female screw portion of the screw hole 2e, the screw 3 is lifted, and a washer attached to the head 3a of the screw 3 ( A gap g is formed between the washer 3c and the printed circuit board 1.

JP 2000-53068 A

  In the device in which the printed circuit board 1 is screwed to the frame 2, if the screw 3 that fixes the printed circuit board to the frame is lifted, the above-described problem occurs, causing the device to malfunction. When manufacturing the product, check whether the screw fixing the printed circuit board to the frame is floating, and if the screw is floating, replace the screw or retighten the screw There is a need. Therefore, conventionally, the presence or absence of the floating of the screw has been inspected by visually confirming the presence or absence of the gap g between the head 3a of the screw 3 and the printed circuit board 1 using a gap gauge.

  As described above, conventionally, since the presence or absence of lifting of the screw for fixing the printed circuit board to the frame of the apparatus has been visually inspected using a gap gauge, not only the inspection takes time but also the operator who performs the inspection There is a problem that the inspection result varies depending on the skill of the method.

  An object of the present invention is to easily and accurately inspect the floating of a screw in a printed circuit board on which components constituting an electronic circuit are mounted and fixed to a frame of a device having the electronic circuit as one of the components. Is to make it possible to do.

  The present invention comprises a printed circuit board formed with a wiring pattern on an insulating substrate, and a component of an electronic circuit mounted on the printed circuit board, and a frame of an apparatus having the electronic circuit as one of the components. A printed circuit that is fixed by a screw that passes through a printed board and is screwed into a frame is an object.

  In the present invention, a continuity check land is formed around the opening of the screw insertion hole provided in the printed circuit board on the side opposite to the frame in order to penetrate the screw. This continuity check land is formed so that when the screw is screwed into the screw hole of the frame through the screw insertion hole and is tightened to the printed circuit board, the head portion of the screw contacts directly or via a washer. And checking the electrical continuity between the screw head screwed into the frame through the screw insertion hole and the continuity check land so that the screw screwed into the frame can be inspected for floating. It is configured.

  In the state where the above printed circuit board is fixed to the frame of the device, if the screw screwed into the frame through the screw insertion hole of the printed board does not float, the screw head is checked for continuity. Since it is in contact with the land, the screw and the continuity check land are in an electrically connected state. On the other hand, when the screw is floating, a gap is formed between the screw head and the continuity check land, so that the screw and the continuity check land are electrically disconnected. It is in the state. Therefore, after performing the work of screwing the printed circuit board to the frame, apply the tester terminal rod to the head of the screw and the continuity check land, and the electrical continuity between the screw and the continuity check land. By checking whether or not the screw is taken, it is possible to instantaneously and accurately check whether or not the screw is lifted.

  In addition, when configured as described above, the electrical contact resistance between the screw and the continuity check land is insufficient when the screw tightening force is insufficient and the head of the screw is in light contact with the continuity check land. Is large, but when the screw is sufficiently tightened and the head of the screw is in contact with the continuity check land with sufficient contact pressure, electrical contact between the screw and the continuity check land Resistance shows a small value. Therefore, when checking whether electrical continuity between the screw and the continuity check land is taken or not, if the electrical contact resistance between the two is measured, the screw is sufficiently tightened. It can also be checked whether or not it is.

  In a preferred aspect of the present invention, the continuity check land formed around the opening of the screw insertion hole has an annular portion concentrically surrounding the opening of the screw insertion hole, and one end connected to the outer periphery of the annular portion. And a check terminal pattern extending long in a direction away from the annular portion. In this case, the inner diameter of the annular portion of the continuity check land is set to be larger than the inner diameter of the screw insertion hole, and the continuity state is checked by bringing the test terminal bar into contact with the check terminal pattern and the screw head. Configured to get.

  If comprised as mentioned above, a check terminal pattern can be provided in the state extended to the position away from the head part of a screw. Therefore, when conducting the energization check by bringing the pair of terminal bars of the tester into contact with the head of the screw and the land for continuity check, respectively, the pair of terminal bars of the tester can be disposed at an appropriate distance. Work can be easily performed.

  In another preferred aspect of the present invention, the continuity check land formed at the periphery of the opening portion of the screw insertion hole is formed to have an annular portion concentrically surrounding the opening portion of the screw insertion hole. The inner diameter of the annular portion of the land for use is set larger than the inner diameter of the screw insertion hole. The outer diameter of the annular portion of the continuity check land is set to be larger than the outer diameter of the screw head screwed into the screw hole of the frame through the screw insertion hole. Further, it is configured such that the conduction state can be checked by bringing the terminal rod of the tester into contact with each other.

  With the configuration described above, the portion near the outer periphery of the annular portion of the continuity check land can be used as a check terminal land to which the tester terminal rod is applied, so that the shape of the continuity check land is prevented from becoming complicated. be able to.

  According to the present invention, there is a screw head screwed into the frame through the screw insertion hole and tightened around the opening on the opposite side of the frame of the screw insertion hole provided in the printed circuit board to allow the screw to pass therethrough. Since the continuity check land having a part that directly or through a washer is provided, after the work of screwing the printed circuit board to the frame, the tester terminal rod is connected to the screw head and the continuity check land. To check whether or not the screw is lifted up by checking whether or not there is electrical continuity between the screw and the continuity check land. Can do. Therefore, as in the case of performing an inspection using a gap gauge, the inspection result can be efficiently and accurately inspected for the presence or absence of a screw lift by eliminating the possibility of variations in the inspection result depending on the skill of the operator performing the inspection. .

It is sectional drawing which showed the state which attached the printed circuit board concerning one Embodiment of this invention to the flame | frame of the motor. It is a front view of the printed circuit board concerning one Embodiment of this invention. FIG. 3 is a front view showing an example of a pattern of continuity check lands provided on the printed circuit board. It is sectional drawing of the principal part which showed the state which attached the printed circuit board concerning one Embodiment of this invention to the flame | frame of an apparatus. It is sectional drawing of the principal part which showed the state which the float produced in the screw, when fixing the conventional printed circuit board to the flame | frame of an apparatus.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to a printed circuit board 11 constituting a motor controller. In FIG. 1, reference numeral 12 denotes a frame constituting a part (end plate) of a motor case. The frame 12 is formed in a cylindrical shape having a peripheral wall portion 12a and a bottom wall portion 12b. Inside the bottom wall portion 12b of the frame 12, there are a boss portion 12c that holds a bearing that supports a rotating shaft of a rotor (not shown), and an annular printed circuit board mounting base portion 12d that concentrically surrounds the boss portion 12c. Is formed. The pedestal portion 12d is provided with a bag-like screw hole 12e (not penetrating the frame) extending in the axial direction of the motor and a positioning projection 12f for positioning the printed circuit board. In the present embodiment, three screw holes 12e are provided with an interval of 120 degrees.

  The printed circuit board 11 includes a printed circuit board 11a formed by forming a wiring pattern (not shown) on an insulating substrate, and components of an electronic circuit mounted on the printed circuit board 11a. In the illustrated example, as shown in FIG. 2, the insulating substrate 11a1 constituting the printed circuit board 11a is formed to have a substantially disk shape, and a rotor portion (not shown) is formed at the center thereof. A hole 11b for penetrating the rotating shaft is formed. The printed board 11a is provided with three screw insertion holes 11c (not shown in FIG. 2) that are respectively aligned with the three screw holes 12e of the frame, and holes 11f into which the positioning protrusions 12f are fitted. ing. As shown in FIG. 2, an electronic component 15 constituting an electronic circuit of a motor controller is mounted on the printed board 11a.

  The printed circuit board 11 is fixed to the frame 12 by screws 13 screwed into the screw holes 12e of the frame 12 through screw insertion holes 11c provided through the printed board 11a. The screw 13 has a head portion 13a and a shaft portion 13b, and the length of the shaft portion 13b is set shorter than the effective length (axial length) of the female screw portion of the screw hole 12e. In the illustrated example, a washer 13c is attached to the head 13a of the screw 13. When the screw is tightened, the head 13a is opposite to the frame of the screw insertion hole 11c of the printed circuit board 11 via the washer 13c. It is made to contact the periphery of the side opening.

  In the present embodiment, as shown in FIG. 3, the frame 12 passes through the screw insertion hole 11c around the opening on the opposite side to the frame 12 of each screw insertion hole 11c provided in a state of penetrating the printed board 11a. A continuity check land 11i having a portion where the head portion 13a of the screw 13 screwed into the screw hole 12e contacts directly or via a washer is formed.

  The illustrated continuity check land 11i includes a circular annular portion 11i1 concentrically surrounding each screw insertion hole 11c, and one end of the screw 13 screwed into the frame through the screw insertion hole 11c. The check terminal pattern 11i2 is provided so as to extend in a direction away from the annular portion 11i1 so as not to be hidden by the head 13a. In the illustrated example, the check terminal pattern 11i2 is provided so as to extend linearly outward of the annular portion 11i1 along the radial direction of the annular portion 11i1, and the tip of the check terminal pattern 11i2 is a circular shape that contacts the terminal rod of the tester. The electrode portion 11i3 is formed.

  The inner diameter of the annular portion 11i1 of the continuity check land 11i is set larger than the inner diameter of the screw insertion hole 11c, and is covered with the continuity check land 11i between the inner peripheral portion of the annular portion 11i1 and the screw insertion hole 11c. A ring-shaped insulating portion 11j that is not left is left. The insulating portion 11j prevents the shaft portion 13b of the screw 13 inserted into the screw insertion hole 11c from contacting the continuity check land 11i. The outer diameter of the annular portion 11i1 is set to be slightly larger than the outer diameter of the washer 13c attached to the head 13 of the screw 13 screwed into the screw hole 12e of the frame through the screw insertion hole 11c. When the head portion 13a is brought into contact with the annular portion 11i1 of the continuity check land 11i through the washer 13c after being tightened to the substrate, the portion near the outer periphery of the annular portion 11i1 protrudes to the outside of the outer periphery of the washer 13c. It is arranged in the state.

  According to the present embodiment, after the screw 13 is screwed into the screw hole 12e of the frame 12 through the screw insertion hole 11c of the printed circuit board 11, as shown in FIG. 4, the screw head 13a and the check terminal pattern 11i2 Inspecting whether or not the screw 13 is lifted by checking the continuity between the screw 13 and the continuity check land 11i by bringing the tester's terminal rods 21 and 22 into contact with the terminal portion 11i3. Can do. That is, when there is continuity between the screw 13 and the continuity check land 11i, it can be determined that the screw 13 does not float, and there is no continuity between the screw 13 and the continuity check land 11i. It can be determined that the screw 13 has a float. If the printed circuit boards 11 are the same, the position of each continuity check land 11i is constant, so this inspection can be easily automated.

  When only the presence / absence of conduction between the screw 13 and the continuity check land 11i is viewed, the continuity can be obtained even when the head of the screw 13 is in light contact with the continuity check land. However, it is not always possible to accurately detect that a screw is securely tightened with a predetermined tightening torque. However, when an apparatus is assembled at a factory, an automatic machine is generally used to tighten the screw. If the length of the shaft portion 13b of the screw 13 matches the effective length of the female screw portion of the screw hole 12e, the screw is always securely tightened. Since it is necessary to inspect only the screw floating caused by the mismatch between the length of the shaft portion 13b of the screw 13 and the effective length of the female screw portion of the screw hole 12e, the screw 13 and the continuity check land 11i are simply Even if the inspection is performed only by checking the presence / absence of conduction between the two, there is no problem.

  However, when the continuity check land is provided on the printed circuit board as in this embodiment, it is possible not only to inspect the presence or absence of the screw floating, but also the electrical connection between the screw 13 and the continuity check land 11i. By measuring a simple contact resistance, it is possible to check whether or not the screw 13 is securely tightened.

  That is, when the tightening force of the screw 13 is insufficient and the head portion 13a of the screw is lightly in contact with the continuity check land 11i, the electrical contact resistance between the screw 13 and the continuity check land 11i is low. Although the screw is sufficiently tightened and the head portion 13a of the screw is in contact with the continuity check land 11i with sufficient contact pressure, the electrical connection between the screw and the continuity check land is large. Since the contact resistance shows a small value, when checking whether electrical continuity between the screw 13 and the continuity check land 11i is taken, the electrical contact resistance between them is also measured. By doing so, it is possible to check whether or not the screw is sufficiently tightened.

  In the above embodiment, the check terminal pattern 11i3 is provided in the continuity check land 11i. However, the present invention is not limited to the case where the check terminal pattern 11i3 is provided as described above, and the opening portion of the screw insertion hole. The continuity check land provided on the periphery of the screw 13 is formed only by an annular portion concentrically surrounding the opening of the screw insertion hole 11c, and the outer diameter of the annular portion is set to the outer diameter (washer) of the head 13a of the screw 13. If the outer diameter of the washer is set to be sufficiently larger than the outer diameter of the washer, the terminal rod of the tester may be brought into contact with the portion near the outer periphery of the annular portion of the continuity check land. That is, by enlarging the diameter of the annular portion 11i1 of the continuity check land 11i of the above embodiment and providing the annular portion with a function as a check terminal pattern, the check terminal pattern is omitted and the continuity check The land 11i can be formed in a simple shape.

  In the above embodiment, the screw 13 having the washer 13c attached to the head 13a is used. However, when the screw head 13a is directly brought into contact with the printed circuit board and tightened without providing the washer, Of course, the present invention can be applied.

DESCRIPTION OF SYMBOLS 11 Printed circuit board 11a Printed circuit board 11c Screw insertion hole 11i Land for continuity check 11i1 Annular part of land for continuity check 11i2 Check terminal pattern 12 Frame to which printed circuit board is attached 12e Bag-shaped screw hole

Claims (3)

A printed circuit board having a wiring pattern formed on an insulating substrate, and an electronic circuit component mounted on the printed circuit board, the printed circuit board being mounted on a frame of an apparatus having the electronic circuit as one of the components. In a printed circuit board that is fixed by a screw that penetrates and is screwed into the frame,
A continuity check land is formed around the opening opposite to the frame of the screw insertion hole provided in the printed circuit board to allow the screw to pass through.
The continuity check land is a portion where the head of the screw contacts directly or through a washer when the screw is screwed into the screw hole of the frame through the screw insertion hole and is tightened to the printed circuit board. Formed to have
By checking the electrical continuity between the head of the screw screwed into the frame through the screw insertion hole and the continuity check land, the presence or absence of floating of the screw screwed into the frame is checked. A printed circuit board configured to obtain a printed circuit board. The continuity check land formed around the opening of the screw insertion hole has an annular portion that concentrically surrounds the opening of the screw insertion hole, and one end connected to the outer peripheral portion of the annular portion. A check terminal pattern extending in a direction away from the check terminal pattern,
An inner diameter of the annular portion of the continuity check land is set larger than an inner diameter of the screw insertion hole,
2. The printed circuit board according to claim 1, wherein the conductive state can be checked by bringing a terminal rod of a tester into contact with the check terminal pattern and the screw head. 3. The continuity check land formed at the periphery of the opening of the screw insertion hole is formed to have an annular portion that concentrically surrounds the opening of the screw insertion hole,
An inner diameter of the annular portion of the continuity check land is set larger than an inner diameter of the screw insertion hole,
The outer diameter of the annular portion of the continuity check land is set to be larger than the outer diameter of the head portion of the screw screwed into the screw hole of the frame through the screw insertion hole, The printed circuit board according to claim 1, wherein the conductive state can be checked by bringing a terminal rod of a tester into contact with a head of the screw.

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