Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-05-15
2002-12-03
Martin, David (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C174S13800J
Reexamination Certificate
active
06490164
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an attachment structure to a circuit board, for example, for attaching an electronic component such as an instrument movement or the like to a rigid circuit board, and a clip used in the attachment. Particularly, the present invention relates to an attachment structure of an electronic component to a circuit board, by which the workability and economy in attachment of an attachment member to a rigid circuit board can be enhanced, and a clip for use in the attachment.
2. Description of the Related Art
For example, a conventional structure with which an instrument movement (electronic component) for use in assembling an on-vehicle instrument apparatus is attached to a rigid circuit board of the on-vehicle instrument apparatus will be described with reference to FIG.
10
. The reference numeral
1
represents a rigid circuit board. A predetermined printed pattern circuit
2
is formed in the lower surface of the rigid circuit board
1
.
The reference numeral
3
represents an instrument movement such as a speedometer, an engine tachometer, or the like, attached to the upper surface of the rigid circuit board
1
. Although the instrument movement
3
does not have a feature in internal configuration, the schematic configuration thereof will be described as follows. The reference numeral
4
represents a housing made of resin. The housing
4
also has a function as a coil bobbin. Inside the housing
4
, a movable magnet
5
is rotatably supported through a pointer shaft
6
. In addition, a pair of coils are wound and retained around the housing
4
perpendicularly to each other so as to form a cross coil
7
.
The reference numeral
8
represents a shield case disposed to cover the outside of the cross coil
7
;
9
, connection terminals connected to the cross coil
7
; and
10
, a pointer attached to a forward end of the pointer shaft
6
.
When the instrument movement
3
configured thus is attached to the rigid circuit board
1
, the instrument movement
3
is put on the upper surface of the rigid circuit board
1
. Further, attachment holes
11
provided in the rigid circuit board
1
are made to agree with threaded holes
12
formed in the housing
4
of the instrument movement
3
. Then, attachment screws
13
are made to pass through the attachment holes
11
from the lower surface (back side) of the rigid circuit board
1
. The attachment screws
13
are screwed down into the threaded holes
12
of the instrument movement
3
so that the rigid circuit board
1
and the instrument movement
3
are screwed to each other.
In such a manner, in the attachment structure in which the rigid circuit board
1
and the instrument movement
3
are screwed to each other by the attachment screws
13
, a plurality of attachment screws
13
for screwing must be prepared in advance, and a screwing step for screwing the plurality of attachment screws is required. From such a point, the attachment structure is inferior in the workability and economy in attachment of the instrument movement.
In addition, after the instrument movement
3
is screwed to the rigid circuit board
1
, the lower surface of the rigid circuit board
1
is immersed in a flow soldering tank so that the connection terminals
9
projecting from the lower surface of the rigid circuit board
1
are soldered with the printed circuit
2
. At this time, however, there arises a problem that solder balls repelled by the head portions of the attachment screws
13
adhere to a circuit portion of the rigid circuit board so as to cause an electric connection failure (short-circuit due to a solder bridge or the like).
As mentioned above, when the head of each attachment screw is immersed into the flow soldering tank, the head thereof might repel the solder to form the solder balls. On occasion, the solder balls are attached to another soldering potion which might arise a loose connection in the circuit board
1
. In order to avoid the loose connection, in the conventional art, the IC, the resistor and the like except for the instrument movement
3
are flow-soldered in the flow soldering bath to electrically fix them to the circuit board
1
. After that, the instrument movement
3
is screwed and fixed to the circuit board
1
, and then the terminals of the instrument movement
3
are spot-soldered with the wiring pattern of the circuit board
1
so that the instrument movement
3
is fixed and electrically connected with the circuit board
1
. Therefore, the soldering of the instrument movement
3
and the soldering of other electronic components, such as an IC, a resistor and the like, have to be performed in separate steps, respectively. Two soldering steps are required in total.
To solve such a problem, it can be considered to give surface treatment to the head portions of the attachment screws
13
so as to make solder easy to adhere to the head portions. However, it is not practical because the treatment cost increases when surface treatment is given to the respective head portions of the attachment screws
13
so as to make solder easy to adhere to the head portions.
On the other hand, if the soldering is carried out by a robot without using the flow soldering tank as means for soldering the connection terminals
9
with the circuit portion of the rigid circuit board, it is possible to restrain generation of solder balls on the head portions of the attachment screws
13
. However, in such robot soldering means, it is necessary to solder respective portions to be soldered one by one. Therefore, it takes much time for soldering so that the assembling productivity deteriorates.
Alternately, there has been proposed to provide a resin engagement nail integrally formed with a resin bobbin with which a coil is wound. In the attachment process, the resin engagement nail is fixed to the circuit board
1
. However, since the engagement nail is made of resin, the resin engagement nail deforms due to the heat generated in the flow soldering. To avoid the deformation of the resin engagement nail, only the IC, the resistor and the like are flow-soldered in the flow soldering bath to electrically fix them to the circuit board
1
. After that, the instrument movement
3
is fixed to the circuit board
1
through the resin engagement nail, and then the terminals of the instrument movement
3
are spot soldered with the printing pattern of the circuit board
1
so that the instrument movement
3
is fixed and electrically connected with the circuit board
1
without deformation of the resin engagement nail. In this method, the two soldering steps are also required in total.
To improve the attaching efficiency of the instrument movement
3
, it is possible to use a bobbin a resin engagement nail made of high heat resistance resin. However, the high heat resistance resin is expensive in general, which increases the manufacturing cost thereof, and therefore it is not practical.
SUMMARY OF THE INVENTION
The present invention is made in consideration of such facts in the conventional. It is an object of the present invention to enable an electronic component such as an instrument movement or the like to be fixed to a rigid circuit board simply and easily without using any attachment screw when the electronic component is attached to the rigid circuit board, so that the number of man-hours for fastening attachment screws is omitted.
It is also an object of the present invention to carry out the soldering work for a connection circuit in the lower surface (back surface) of the rigid circuit board by use of a flow soldering tank so that the workability and economy of the soldering are enhanced.
To attain the foregoing first and second objects, according to an aspect of the present invention, there is provided an attachment structure of an electronic component to a circuit board comprising: a rigid circuit board having a suitable circuit pattern formed on a back surface thereof, having one or more attachment holes formed in the rigid circuit board for attachment of an
Hino Shoji
Takahashi Hideyuki
Calsonic Kansei Corporation
Martin David
Tran Thanh Y.
LandOfFree
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