Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – With provision to conduct electricity from panel circuit to...
Reexamination Certificate
2000-08-17
2001-11-13
Sircus, Brian (Department: 2839)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
With provision to conduct electricity from panel circuit to...
C310S320000
Reexamination Certificate
active
06315577
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electronic components having lead terminals that include substantially cylindrical wires, and relates to the lead terminals.
2. Description of the Related Art
Electronic components having leads with lead terminals joined thereto have been extensively used as electronic component elements such as piezoelectric resonators.
FIG. 5
is a schematic perspective view showing a piezoelectric resonator component as an example of a conventional electronic component having leads.
In a piezoelectric resonator component
51
, a plurality of lead terminals
53
to
55
are connected to a piezoelectric resonator
52
shown in phantom line. Although not shown in the figure, a remaining portion, excluding a portion in the vicinity of an end portion opposite to the side to be joined to the piezoelectric resonator
52
, of the lead terminals
53
to
55
is covered by an exterior resin layer C.
The above-described lead terminals
53
to
55
are made by bending a flat metal sheet. A portion in the vicinity of one end portion of the lead terminal
53
is a terminal fitting part
53
a,
and is electrically and mechanically connected to an electrode (not shown) of the piezoelectric resonator
52
with solder or other suitable connection element. A stopper
53
b
is provided in the center of the lead terminal
53
in its longitudinal direction. The stopper
53
b
is configured to be wider than an end part
54
c
of a side to be inserted in a printed circuit board or other suitable device of the lead terminal
53
. The stopper
53
b
is provided to adjust the insertion depth when the printed circuit board is inserted in a fitting hole.
The lead terminals
53
to
55
are formed by punching a metal sheet and by bending a part of the punched metal sheet.
Thus, the lead terminals
53
to
55
are easily formed by punching and bending a metal sheet.
However, the lead terminals
53
to
55
formed from a flat metal sheet are thinner than lead terminals formed of a cylindrical wire. Thus, extra parts of the lead terminals
53
to
55
are often unsuccessfully cut by an automatic inserting machine.
Also, during automatic mounting, the lead terminal
53
is inserted in a through hole in a printed circuit board, and a tip side of the lead terminal
53
is often bent in the direction that is perpendicular relative to the axial direction of the through hole, i.e., is often cut and crimped. However, in the above-described lead terminals
53
to
55
, no part to absorb impact is present between the exterior resin layer C and the stopper
53
b.
Thus, exterior resin layers and piezoelectric resonators are often cracked by the impacts generated by the cutting and crimping.
To prevent such cracks, tests have been tried to increase the strength of the exterior resin layer C, but when the strength of the exterior resin layer C is increased, the electric characteristics of the piezoelectric resonator are often adversely affected.
A lead terminal
56
shown in
FIG. 6
is also proposed in order to improve cutting ability when cutting off extra parts of the lead terminal in the automatic inserting machine. The lead terminal
56
is provided by preparing a cylindrical wire, and flattening a part in the vicinity of one end part of the cylindrical wire to form a fitting part
56
a
and a flat stopper
56
b
which is wider than the fitting part
56
a.
A portion
56
c
of the lead terminal
56
which is led out of the exterior resin layer and is inserted in the through hole in the printed circuit board is cylindrical, and thus, the ability to cut off extra portions of the lead terminal is improved in mounting by the automatic inserting machine.
However, no impact absorbing part is present either in the lead terminal
56
between the exterior resin layer and the stopper
56
b,
and thus, exterior resin layers and piezoelectric resonators are often cracked by impacts during the cutting and crimping work.
In addition, the stopper
56
b
is formed by flattening a cylindrical wire, and thus, the thickness of the wide stopper
56
b
is likely to be very thin, causing a problem in that the bending strength of the lead terminal
56
is degraded.
On the other hand, lead terminals
57
and
58
shown in
FIG. 7
are well known to absorb impacts in the above-described automatic mounting. The lead terminals
57
and
58
are extensively used as lead terminals in a capacitor element
59
. That is, kinks
57
a
and
58
a
which are formed by bending a portion of the cylindrical wire and are curved from side to side are provided on the lead terminals
57
and
58
. Since the kinks
57
a
and
58
a
are formed, the impact in mounting on the printed circuit board is effectively absorbed by the kinks
57
a
and
58
a.
However, when the lead terminals
57
and
58
are applied to piezoelectric components such as piezoelectric resonators, it is necessary to provide a cavity so as not to interfere with the oscillation of the piezoelectric resonator within the exterior resin layer. Furthermore, to miniaturize the product, it is necessary to reduce the dimensions of the portion of the lead terminals to be covered with the exterior resin. As a result, the pull-out strength of the lead terminals
57
and
58
against the exterior resin layer is insufficient if the lead terminals
57
and
58
formed of the cylindrical wire having only the kinks
57
a
and
58
a
are used in the piezoelectric resonator. At the same time, if a torsional force is applied to twist the lead terminals
57
and
58
in the axial direction, the lead terminals
57
and
58
are easily twisted, so that there is a concern that the exterior resin layer will be cracked and that portions joined to the piezoelectric resonator will be broken.
SUMMARY OF THE INVENTION
To overcome the above described problems, preferred embodiments of the present invention provide electronic components having leads which are provided with lead terminals that are capable of overcoming disadvantages in the above-described conventional technology, and absorbing impacts during automatic mounting on printed circuit boards, and which are superior in pull-out strength against the exterior resin layer and are also superior in torsional strength in the axial direction, and to provide such lead terminals in the electronic components.
Electronic components having leads according to preferred embodiments of the present invention include electronic component elements, plural lead terminals which are provided with first and second end parts and which are joined with the above-described electronic component elements at the first end part side, and an exterior resin layer to cover the above-described electronic component elements with a part in the vicinity of the second end part of the above-described lead terminals exposed, wherein at least one of the lead terminals is made by providing a cylindrical wire having a fitting part having a flattened portion in the vicinity of the first end part, a kink bent between the first and second end parts, and first and second flat parts provided at the position to be covered by the exterior resin layer between the fitting part and the kink.
The above-described exterior resin layer is preferably provided with a relatively soft inner first exterior resin layer and a relatively hard outer second exterior resin layer, wherein the first flat part is covered with the first exterior resin layer and the second flat part is covered with the second exterior resin layer.
According to one preferred embodiment of the present invention, the above-described electronic component elements are preferably piezoelectric elements, and a cavity is provided around an oscillating portion of the piezoelectric element so as not to interfere with the oscillating of the piezoelectric element.
The lead terminal of preferred embodiments of the present invention is used for electronic components having leads, and is formed by providing the cylindrical wire with a fitting part flattened in the vicinity of the first end p
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Nguyen Son V.
Sircus Brian
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