Inductor devices – Coil or coil turn supports or spacers – Printed circuit-type coil
Reexamination Certificate
2002-04-08
2004-01-06
Nguyen, Tuyen T. (Department: 2832)
Inductor devices
Coil or coil turn supports or spacers
Printed circuit-type coil
C336S083000, C333S001100
Reexamination Certificate
active
06674354
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to non-reciprocal circuit elements, communication devices, and methods of manufacturing the non-reciprocal circuit elements.
2. Description of the Related Art
Non-reciprocal circuit elements for lumped-constant isolators used in mobile communication devices, such as cellular phones, generally have a function for transmitting signals in one direction and preventing the transmission in the other direction. A non-reciprocal circuit element comprises a permanent magnet, a center electrode assembly including a ferrite and a plurality of center electrodes disposed on the ferrite. The magnet is disposed in a region defined by a metallic component and the center electrode assembly is disposed in a region defined by a resin component combined with the metallic component.
FIG. 20
is a plan view of a resin component
3
. The resin component
3
is combined with a lower metallic component
4
to form a case. A bottom
3
a
of the resin component
3
is provided with connection electrodes (an input-lead-out electrode
14
a
, an output-lead-out electrode
15
a
, and an intermediary electrode
17
) electrically connected to center electrodes. The bottom
3
a
has windows to define a first cell
3
c
and second cells
3
d
, and the lower metallic component
4
is exposed in the first and second cells
3
c
and
3
d
to serve as grounding-lead-out electrodes
4
a
. One grounding-lead-out electrode
4
a
exposed in the first cell
3
c
which is in the center of the bottom
3
a
is electrically connected to a grounding electrode of the center electrode assembly. The other grounding-lead-out electrodes
4
a
exposed in the second cells
3
d
are electrically connected to electrical functional components such as matching capacitors. These connections are ensured by, for example, a soldering paste
60
. The soldering paste
60
is applied to the electrodes
4
a
,
14
a
,
15
a
,
17
, and the like with a dispenser. The soldering paste
60
may consist essentially of Sn—Sb, Sn—Pb, or Sn—Ag, for example. The surface color of the soldering paste is gray.
The lower metallic component
4
, which serves as the grounding-lead-out electrodes
4
a
, and the connection electrodes
14
a
,
15
a
, and
17
are formed by nickel plating (typically 1 &mgr;m thick) and silver plating (typically 4 &mgr;m thick), in that order, on base iron. The surface color of the electrodes
4
a
,
14
a
,
15
a
and
17
is silver.
The resin component
3
is formed of a liquid crystalline polymer. Liquid crystalline polymers are originally white, but the polymer used for the resin component
3
contains a black colorant in order to hide dirt thereon.
Mobile communication devices are increasingly required to be small and inexpensive and to have improved reliability in use. Hence, isolators, or non-reciprocal circuit elements, used for the communication devices also must be small and inexpensive, and have improved reliability. Accordingly, the electrical functional components and the resin component
3
included in the non-reciprocal circuit elements are required to be small.
Unfortunately, if the resin component
3
and the electrical functional components are directly miniaturized, the miniaturized resin component
3
and electrical functional components are likely to cause soldering problems at the connection electrodes
14
a
,
15
a
, and
17
and at the electrodes of the electrical functional components. For example, the use of too little soldering paste
60
is liable to cause an open circuit at the connection electrodes
14
a
,
15
a
, and
17
and matching capacitors. Also, the use of too much soldering paste
60
(see the soldering paste
60
applied on the connection electrode
15
a
in
FIG. 20
) is liable to cause a short circuit because the soldering paste
60
comes into contact with undesired areas.
In order to prevent any open circuit and short circuit in the non-reciprocal circuit element, the soldering paste
60
must be applied to the connection electrodes
14
a
,
15
a
and
17
and electrodes of the electrical functional components while being controlled within a predetermined range. Controlling the amount of soldering paste
60
becomes increasingly important according to the miniaturization of the non-reciprocal circuit element. For controlling the amount of soldering paste
60
, visual examination and image analysis may be performed. However, visual examination is inefficient, and therefore is not suitable for mass production.
In contrast, image analysis is efficient and suitable for mass production. Generally, exposing an object to visible light causes reflection, at the surface of the object, having an intensity in proportion to the light reflectance of the object. The intensity of the reflection is determined by an image pickup tube, and an output of the image pickup tube can be processed to form an image. In this image, a white image represents an area causing a strong reflection and a black image represents an area causing a weak reflection. In other words, when an object is exposed evenly to a substantially constant visible light, an area forming a white image has a high light reflectance and, in contrast, an area forming a black image has a low light reflectance. In this image analysis, the image is binarized according to two levels which indicate black and white, respectively, and thus the amount of soldering paste
60
is determined according to the binarized image.
However, if the threshold for the black-and-white binarization is set between the image formed by the reflection at the soldering paste
60
and the images formed by the reflections at the connection electrodes
14
a
,
15
a
, and
17
, the soldering paste
60
and the resin component
3
are not distinguished from each other.
More specifically, the reflections at the connection electrodes
14
a
,
15
a
, and
17
are the strongest, the reflection at the soldering paste
60
is the second strongest, and the reflection at the resin component
3
is the weakest because surface colors of the connection electrodes
14
a
,
15
a
, and
17
, the soldering paste
60
, and the resin component
3
are silver, gray, and black, respectively. Therefore, if the threshold for the binarization of the image is set between the image formed by the reflection at the soldering paste
60
and the images formed by the reflections at the connection electrodes
14
a
,
15
a
, and
17
, the soldering paste
60
and the resin component
3
are not distinguishable from each other. Hence, it is impossible to detect when soldering paste
60
is spreading to the connection electrode
15
a
, nor consequently can it be determined whether the soldering paste
60
is applied within a predetermined range.
For a solution of this problem, it has been suggested that two thresholds be set. A first threshold is set between the image formed by the reflection at the resin component
3
and the image formed by the reflection at the soldering paste
60
, and a second threshold is set between the image formed by the reflection at the soldering paste
60
and the image formed by the reflections at the connection electrodes
14
a
,
15
a
, and
17
. Thus, the soldering paste
60
can be distinguished from the connection electrodes
14
a
,
15
a
,
17
and the resin component
3
. However, this solution requires an expensive image analyzer and therefore leads to expensive non-reciprocal circuit elements.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a miniaturized, inexpensive, and reliable non-reciprocal circuit element and communication device and a method of manufacturing the non-reciprocal circuit element.
To this end, according to one aspect of the present invention, there is provided a non-reciprocal circuit element comprising:
a metallic component,
a resin component combined with said metallic component,
a ferrite,
a permanent magnet, which applies a DC magnetic flux to the ferrite, and
a center electrode assembly comprising a plurality of center electrodes which are dis
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Nguyen Tuyen T.
LandOfFree
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