U.S. patent application number 09/838839 was filed with the patent office on 2001-08-16 for apparatus for forming electrode of chip-like electronic part.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Fukuda, Makoto, Nakagawa, Tadahiro.
Application Number | 20010013602 09/838839 |
Document ID | / |
Family ID | 16384527 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013602 |
Kind Code |
A1 |
Nakagawa, Tadahiro ; et
al. |
August 16, 2001 |
Apparatus for forming electrode of chip-like electronic part
Abstract
An electrode is formed on a chip-like electronic part of the
type having a central axis, a polygonal cross section as viewed in
a plane which is perpendicular to the central axis, a plurality of
side surfaces extending in respective planes which are generally
parallel to the central axis, and a pair of end surfaces extending
generally parallel to the central axis, each adjacent pair of side
surfaces meeting along a respective edge of the chip-like
electronic part. The electrode is formed by applying a first band
of conductive material to at least one of the side surfaces and
applying a second band of conductive material to the remaining side
surface(s) in such a manner that the first and second bands meet at
respective ones of the edges and together form a continuous band of
conductive material extending around the outer periphery of the
chip-type electronic part. The chip-like electronic part is held by
a holder with a first plurality of side surfaces being exposed and
facing a paste base on which a streak of conductive material is
placed. The holder and paste base are brought together so that the
first band of conductive material is applied to the first plurality
of side surfaces. The chip-like electronic part is then
repositioned with its remaining side surfaces being exposed and
facing a paste base and the second band of conductive material is
applied to those side surfaces.
Inventors: |
Nakagawa, Tadahiro;
(Kyoto-fu, JP) ; Fukuda, Makoto; (Kyoto-fu,
JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
|
Family ID: |
16384527 |
Appl. No.: |
09/838839 |
Filed: |
April 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09838839 |
Apr 20, 2001 |
|
|
|
09122145 |
Jul 24, 1998 |
|
|
|
Current U.S.
Class: |
257/4 |
Current CPC
Class: |
H01G 13/006
20130101 |
Class at
Publication: |
257/4 |
International
Class: |
H01L 047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 24, 1997 |
JP |
9-198039` |
Claims
What is claimed is:
1. A combination, comprising: a chip electronic part having a
plurality of outer surfaces extending generally parallel to a
central axis of the chip electronic part, at least one of the
surfaces having a band of conductive material located thereon; and
a holder holding the chip conductive part in an orientation wherein
at least one of the outer surfaces of the chip electronic part
extends outwardly from the holder and wherein the surface(s) of the
chip electronic part which have the band of conductive material
located thereon face inwardly of the holder and are not
exposed.
2. The combination of claim 1, wherein the holder includes a recess
in which the band of conductive material is located without the
conductive material touching the walls of the recess.
3. The combination of claim 1, wherein the holder has a groove,
including a plurality of side walls, for holding the electronic
part, the shape of the groove corresponding generally to the shape
of the portion of the chip electronic part being held in the
groove.
4. The combination of claim 3, wherein the walls of the chip
electronic part which have the band of conductive material formed
thereon are in contact with the side walls of the groove and the
band of conductive material itself is situated in a recess formed
in the groove such that the band of conductive material does not
contact the walls of the groove or the walls of the recess.
5. The combination of claim 3, wherein the chip electronic part is
formed in a shape of a quadrangular prism and the groove is formed
in a V-like shape.
6. A chip electronic part comprising: a main body portion having a
central axis, a polygonal cross section as viewed in a plane which
is perpendicular to the central axis, a plurality of side surfaces
extending in respective planes which are generally parallel to the
central axis, and a pair of end surfaces extending generally
parallel to the central axis, each adjacent pair of side surfaces
meeting along a respective edge of the main body portion; a pair of
end electrodes located on the end surfaces of the main body
portion; and a central electrode comprising a sintered metal formed
of an electrode paste and extending over each of the side surfaces
of the main body portion so as to extend entirely around the outer
periphery of the main body portion, the central electrode being
formed of two bands of sintered conductive paste, the two bands
meeting at respective edges of the main body portion.
7. The chip electronic part of claim 6, wherein the two respective
edges are located 180 degrees apart from one another as measured
around the central axis of the main body portion.
8. The chip electronic part of claim 7, wherein the two bands
overlap one another at the respective edges.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional of U.S. Pat. application Ser. No.
09/122,145, filed Jul. 24, 1998 in the name of Tadahiro Nakagawa et
al. and entitled "PROCESS OF FORMING ELECTRODE OF CHIP ELECTRONIC
PART."
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a process of forming an
electrode for a chip-like electronic part and a holder for a
chip-like electronic part, particularly to a process of forming an
electrode comprising a conductive paste on an outer surface of a
chip-like electronic part and a holder for a chip-like electronic
part preferably used in carrying out the process.
[0004] 2. Description of Related Art
[0005] FIG. 18 shows a perspective view of a chip-like electronic
part 1, particularly a three terminal capacitor. End electrodes 2
and 3 are formed on respective end portions of the chip-like
electronic part 1 and central electrodes 4 are formed at the
central portion thereof.
[0006] Although not illustrated, first and second groups of inner
electrodes are arranged alternately inside the chip-like electronic
part 1 with the inner electrodes of the first group extending to
the end electrodes 2 and 3 and the inner electrodes of the second
group extending to the central electrodes 4. Accordingly,
electrostatic capacitances formed between the inner electrodes of
the first group and the inner electrodes of the second group can be
taken out between the end electrode 2 or 3 and the central
electrodes 4. The chip-like electronic part 1 is used to, for
example, remove noise on a signal line by coupling the end
electrodes 2 and 3 to the signal line and grounding the central
electrodes 4.
[0007] As shown in FIG. 18, the central electrodes 4 extend across
two opposing side faces of the chip-like electronic part 1. Because
of limitations associated with the process commonly used to make
the chip-like electronic part 1, the central electrodes 4 extend
only partially on the other side faces of the chip-like electronic
part. As a result, the central electrodes 4 do not extend entirely
around the outer side surfaces of the chip-like electronic part
1.
[0008] The process for applying the central electrodes 4 is best
understood with reference to FIG. 19. As shown herein, a groove 6
is provided in a paste base 5 which comprises an elastic body. The
groove 6 is filled with a conductive paste 7 to form an elongated
streak 8 of conductive paste 3. The chip-like electronic part 1 is
held by a holder 9 so that one face of the chip-like electronic
part 1 faces the streak 8 of conductive paste.
[0009] As best seen in FIG. 18, the chip-like electronic part 1 is
an elongated parallel-piped structure having a main axis extending
from end electrode 2 to end electrode 3. The central portion of the
chip-like electronic part 1 is aligned with the streak 8 of
conductive paste with the axis of the streak extending
perpendicular to the central axis of the chip-like electronic part
1. The chip-like electronic part 1 is brought into contact with the
paste base 5 and pressed against the paste base 5 to deform it and
cause the conductive paste 7 to be applied to the outer surface of
the chip-like electronic part 1 as shown by an imaginary line in
FIG. 19. Although the conductive paste 7 extends across the entire
side face of the chip-like electronic part 1 which faces the base
5, it only extends partway up the adjacent side faces of the
chip-like electronic part 1.
[0010] The orientation of the chip-like electronic part 1 is then
reversed so that its opposite face extends away from the holder and
towards the paste base 5 and the process is repeated to place the
conductive paste 7 on the opposite face (and particularly up the
adjacent side faces) of the chip-like electronic part 1.
Thereafter, the so applied central electrodes 4 are cured.
[0011] Instead of placing the conductive paste 7 in a groove 6
provided in the elastic paste base 5, the conductive paste may be
applied (by printing or the like) on a flat face of a paste base 5
which can be either elastic or rigid. As another alternative, a
reservoir of conductive paste located on one side of a slit plate
can be extruded to the other side of the slit plate via the slit in
the plate by applying pressure to the conductive paste.
[0012] The end electrodes 2 and 3 are formed by dipping the ends of
the chip-like electronic part 1 into a tank of conductive
paste.
[0013] As mentioned above, the central electrode 4 does not
normally extend around the entire outer surface of the chip-like
electronic part 1. However, it is preferable that it does to reduce
unnecessary inductance components where the central electrode is
used as a ground electrode.
[0014] It is not impossible to form the central electrode to extend
around the entire circumference of the chip-like electronic part 1
using the process shown in FIG. 19. This result can be achieved by
providing a sufficient amount of conductive paste to extend at
least half way up the two side faces of the chip-like electronic
part 1, for example, by making the groove deeper or pressing the
chip-like electronic part 1 more strongly against the paste base 5.
However, as shown in the sectional view of FIG. 20, overlap
portions 12 are formed on flat end faces of the chip-like
electronic part. These overlap portions 12 can hamper the
mountability of the chip-like electronic part. Accordingly, it is
preferable that a built-up portion, such as the overlap portion 12,
not be formed at the central portion of any of the side faces of
the chip-like electronic part 1.
[0015] This can be avoided by using a small enough amount of
conductive paste that only one side of the chip-like electronic
part receives the paste during any single application. However,
this will necessitate four separate applications of the conductive
paste which is not efficient.
SUMMARY OF THE INVENTION
[0016] It is an object of the present invention to provide a
process of forming an electrode of a chip-like electronic part and
a holder for a chip-like electronic part used in the process which
can resolve the above described problem.
[0017] To this end, the process of the present invention forms an
electrode on a chip-like electronic part of the type having a
central axis, a polygonal cross section as viewed in a plane which
is perpendicular to the central axis, a plurality of side surfaces
extending in respective planes which are generally parallel to the
central axis, and a pair of end surfaces extending generally
parallel to the central axis, each adjacent pair of side surfaces
meeting along a respective edge of the chip-like electronic part,
the process comprising the steps of:
[0018] applying a first band of conductive material to at least one
of the side surfaces; and
[0019] applying a second band of conductive material to the
remaining side surface(s) in such a manner that the first and
second bands meet at respective ones of the edges and together form
a continuous band of conductive material extending around the outer
periphery of the chip-type electronic part.
[0020] In the preferred embodiment, the first and second bands are
applied to the side surfaces at an area that lies between the end
surfaces, and more preferably in the middle, of the chip-like
electronic part and do not extend to either end surface.
[0021] In the preferred embodiment, the chip-like electronic part
has four side surfaces, the first band is applied to first and
second contiguous side surfaces and the second band is applied to
third and fourth contiguous side surfaces by bringing the side
surfaces into contact with strips of conductive paste. The
chip-like electronic part is first held in a holder with the first
and second side surfaces extending outwardly from the holder and
the first band is applied to the first and second side surfaces by
moving a strip of conductive paste located on an elastic paste base
into contact with the first and second side surfaces. Thereafter,
the orientation of the chip-like electronic part is changed by
either moving it within the same holder or moving it to a second
holder to ensure that the third and fourth side surfaces extend
outwardly from the holder. Once in this position, the second band
is applied to the third and fourth side surfaces by moving a strip
of conductive paste located on an elastic paste base into contact
with the third and fourth side surfaces.
[0022] When desired, the first and second bands can be applied to
the side surfaces at an area of the side surfaces located adjacent
one of the end surfaces thereof and can simultaneously be applied
to the adjacent one of the end surfaces as well as the side
surfaces.
[0023] The process of the present invention can also be used to
place a plurality of electrodes on a chip-like electronic part
having a central axis, a polygonal cross section as viewed in a
plane which is perpendicular to the central axis, a plurality of
side surfaces extending in respective planes which are generally
parallel to the central axis, and a pair of end surfaces extending
generally parallel to the central axis, each adjacent pair of side
surfaces meeting along a respective edge of the chip-like
electronic part. In such a case, the process preferably comprising
the steps of:
[0024] applying a set of first bands of conductive material to at
least one of the side surfaces, each of the first bands being
applied at a different axial position on the side surfaces so as to
be spaced from one another; and
[0025] applying a set of second bands of conductive material to the
remaining side surface(s) , each of the second bands being applied
at a different axial position of the remaining side surfaces so as
to be spaced from one another, each band of the first set meeting a
respective band of the first set at two respective edges such that
each respective pair of bands forms a continuous band of conductive
material extending around the outer periphery of the chip-type
electronic part. More preferably, the chip-like electronic part has
four side surfaces and is in the form of a quadrangular prism.
[0026] In the preferred embodiment, three continuous bands are
formed, two adjacent the end surfaces of the chip-like electronic
part, the third at a position intermediate the two end surfaces of
the chip-like electronic part. The bands of conductive material are
applied to the side surfaces by bringing them into contact with
strips of conductive paste. In the preferred embodiment, the first
applying step is carried out by holding the chip-type electronic
part in a holder with the first and second side surfaces extending
outwardly from the holder and the first set of bands are applied to
the first and second side surfaces by moving a plurality of strips
of conductive paste located on an elastic paste base into contact
with the first and second side surfaces. Similarly, the second
applying step is carried out by holding the chip-type electronic
part in a holder with the third and fourth side surfaces extending
outwardly from the holder and the second set of bands is applied to
the third and fourth side surfaces by moving a plurality of strips
of conductive paste located on an elastic paste base into contact
with the third and fourth side surfaces. The same or different
holders can be used for the first and second applying steps.
[0027] According to a further aspect of the process of the present
invention, an electrode is formed on each of a plurality of
chip-like electronic parts of the type having a central axis, a
polygonal cross section as viewed in a plane which is perpendicular
to the central axis, a plurality of side surfaces extending in
respective planes which are generally parallel to the central axis,
and a pair of end surfaces extending generally parallel to the
central axis, each adjacent pair of side surfaces meeting along a
respective edge of the chip-like electronic part, and the process
comprises the steps of:
[0028] simultaneously applying a first band of conductive material
to at least one of the side surfaces of each of the chip-like
electronic parts; and
[0029] simultaneously applying a second band of conductive material
to the remaining side surface(s) of each of the chip-like
electronic parts in such a manner that the first and second bands
of a respective chip-like electronic part meet at respective ones
of the edges on that chip-like electronic part and together form a
continuous band of conductive material extending around the outer
periphery of that chip-type electronic part.
[0030] In the preferred embodiment, each of the chip-like
electronic parts has four side surfaces and each of the first bands
is applied to first and second contiguous side surfaces and wherein
each of the second bands is applied to the remaining two side
surfaces by bringing the side surfaces into contact with strips of
conductive paste. The first applying step is carried out by holding
each of the chip-type electronic parts in a single holder with the
first and second side surfaces of each chip-like electronic part
extending outwardly from the holder and the first band is applied
to the first and second side surfaces of each of the chip-like
electronic parts by moving respective strips of conductive paste
located on an elastic paste base into contact with the first and
second side surfaces. The second applying step is carried out by
holding each of the chip-type electronic parts in a single holder
with the third and fourth side surfaces extending outwardly from
the holder and the second band is applied to the third and fourth
side surfaces by moving strips of conductive paste located on an
elastic paste base into contact with the third and fourth side
surfaces. Again, a single or multiple holders can be used.
[0031] The present invention is also directed toward a combination,
comprising:
[0032] a chip-like electronic part having a plurality of outer
surfaces extending generally parallel to a central axis of the
chip-like electronic part, at least one of the surfaces having a
band of conductive material located thereon; and
[0033] a holder holding the chip-like conductive part in an
orientation wherein at least one of the outer surfaces of the
chip-like electronic part extends outwardly from the holder and
wherein the surface(s) of the chip-like electronic part which have
the band of conductive material located thereon face inwardly of
the holder and are not exposed.
[0034] In the preferred embodiment, the holder includes a recess in
which the band of conductive material is located without the
conductive material touching the walls of the recess. The holder
has a groove, including a plurality of side walls, for holding the
electronic part, the shape of the groove corresponding generally to
the shape of the portion of the chip-like electronic part being
held in the groove. The walls of the chip-like electronic part
which have the band of conductive material formed thereon are
preferably in contact with the side walls of the groove and the
band of conductive material itself is situated in a recess formed
in the groove such that the band of conductive material does not
contact the walls of the groove or the walls of the recess. When
the chip-like electronic part is formed in a shape of a
quadrangular prism, the groove is formed in a V-like shape.
[0035] The present invention is also directed towards a chip-like
electronic part comprising:
[0036] a main body portion having a central axis, a polygonal cross
section as viewed in a plane which is perpendicular to the central
axis, a plurality of side surfaces extending in respective planes
which are generally parallel to the central axis, and a pair of end
surfaces extending generally parallel to the central axis, each
adjacent pair of side surfaces meeting along a respective edge of
the main body portion;
[0037] a pair of end electrodes located on the end surfaces of the
main body portion; and
[0038] a central electrode comprising a sintered metal formed of an
electrode paste and extending over each of the side surfaces of the
main body portion so as to extend entirely around the outer
periphery of the main body portion, the central electrode being
formed of two bands of sintered conductive paste, the two bands
meeting at respective edges of the main body portion.
[0039] The two respective edges are preferably located 180 degrees
apart from one another as measured around the central axis of the
main body portion with the two bands overlapping one another at the
respective edges.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] For the purpose of illustrating the invention, there is
shown in the drawing a form which is presently preferred, it being
understood, however, that the invention is not limited to the
precise arrangement and instrumentality shown.
[0041] FIG. 1 is a perspective view of a chip-like electronic part
21 to which a process of forming an electrode according to one
embodiment of the present invention is applied.
[0042] FIG. 2 is a sectional view showing an inner electrode 25 of
the chip-like electronic part 21 of FIG. 1;
[0043] FIG. 3 is a sectional view showing an inner electrode 26 of
the chip-like electronic part 21 of FIG. 1.
[0044] FIG. 4 is a perspective view of a chip-like electronic part
21a to which a process of forming an electrode according to other
embodiment of the present invention is applied.
[0045] FIG. 5 is a front view showing a plurality of chip-like
electronic parts 21 of FIG. 1 held by a holder 27.
[0046] FIG. 6 is a partial, enlarged front view showing a single
chip-like electronic part 21 held by the holder 27 of FIG. 5.
[0047] FIG. 7 is a side view showing a single chip-like electronic
part being held by the holder 27 of FIG. 5 and also showing a
section of paste base 39.
[0048] FIG. 8 is a view corresponding to FIG. 7 but in which a
paste base 43 is used in place of the paste base 39 of FIG. 7.
[0049] FIG. 9 is a view corresponding to FIG. 7 in which a slit
plate 45 is used in place of the paste base 39 of FIG. 7.
[0050] FIG. 10 a bottom view showing a portion of a holder 27a
which is preferably used in a step of providing a conductive paste
41 at a second time.
[0051] FIG. 11 is a bottom view showing the chip-like electronic
part 21 being held by the holder 27a of FIG. 10.
[0052] FIG. 12 is a sectional view taken along a line XII-XII of
FIG. 11.
[0053] FIG. 13 is a sectional view schematically showing the
chip-like electronic part 21 provided with conductive pastes 41a
and 41b for the central electrode 4 of FIG. 1.
[0054] FIG. 14 is a view corresponding to FIG. 6 showing the
chip-like electronic part 21a of FIG. 4 being held by a holder
27b.
[0055] FIG. 15 is a view corresponding to FIG. 8 for explaining
another embodiment of the present invention.
[0056] FIG. 16A is a perspective view showing the chip-like
electronic part 21 after the conductive paste 41 has been applied
to one-half of the electronic part after having been processed by
the step shown in FIG. 15.
[0057] FIG. 16B is a perspective view showing the chip-like
electronic part 21 after the conductive paste 41 has been applied
to all of the electronic part.
[0058] FIG. 17 is a sectional view for explaining a further
embodiment of the present invention and showing the chip-like
electronic part 21 being held by a holder 27c which is used in
place of the holder 27 shown by FIG. 5 through FIG. 7.
[0059] FIG. 18 is a perspective view of a conventional chip-like
electronic part 1 which is of interest for the present
invention.
[0060] FIG. 19 is a view corresponding to FIG. 7 showing a step of
providing a conductive paste 7 onto the chip-like electronic part 1
to form a central electrode 4.
[0061] FIG. 20 is a sectional view schematically showing the
conductive paste 7 extending along the entry periphery of the outer
surface of the chip-like electronic part 1 using the process shown
in FIG. 19.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0062] Referring now to the drawings wherein like numerals indicate
like elements, there is shown in FIG. 1 a chip-like electronic part
21 on which a central electrode has been formed using a process
corresponding to a first embodiment of the present invention. The
chip-like electronic part 21 is a quadrangular prism having a
section which is substantially square in shape. End electrodes 22
and 23 are respectively formed on opposite end surfaces of the
chip-like electronic part 21 and a central electrode 24 is formed
at the central portion thereof (as measured along the central axis
of the part 21). The central electrode 24 is formed to extend
around the entire periphery of the outer surface of the chip-like
electronic part 21.
[0063] The chip-like electronic part 21 constitutes a three
terminal capacitor having at least one, and preferably a plurality,
of inner electrodes 25 defining a first group of inner electrodes
(one of which is shown in FIG. 2) and at least one, and preferably
a plurality, of inner electrodes 26 defining, a second group of
inner electrodes (one of which is shown in FIG. 3). Individual
electrodes of the first and second groups are arranged alternately
to one another so as to be interleaved. As shown in FIG. 2, the
inner electrodes 25 of the first group are coupled to the end
electrodes 22 and 23. As shown in FIG. 3, the inner electrodes 26
of the second group are coupled to the central electrode 24. The
electrostatic capacitances formed between the inner electrodes 25
of the first group and the inner electrodes 26 of the second group
can be taken out between the end electrode 22 or 23 and the central
electrode 24. The chip-like electronic part 21 can be used, for
example, to remove noise on a signal line by interposing the end
electrodes 22 and 23 in the signal line and grounding the central
electrode 24.
[0064] The process of the present invention can also be used to
apply the central electrode to the chip-like electronic part 21a of
FIG. 4. Chip-like electronic part 21a is substantially similar to
chip-like electronic part 21 of FIG. 1 except that it has a
rectangular cross section. Since the structure is otherwise the
same, no further description is provided.
[0065] An explanation will be provided of a process of forming the
central electrode 24 of the chip-like electronic part 21 shown by
FIG. 1 with reference to FIG. 5 through FIG. 13. Because the end
electrodes 22 and 23 are normally formed after the central
electrode 24 is formed in FIG. 5 through FIG. 9 and FIG. 11 through
FIG. 13, the end electrodes 22 and 23 of the chip-like electronic
part 21 are not illustrated. However, this is not necessarily the
case and the central electrode 24 may be applied after the end
electrodes 22 and 23 have already been formed.
[0066] Referring to FIG. 5, a holder 27 adapted to hold a plurality
of the chip-like electronic parts is attached to a rigid base. An
enlarged view of a portion of the holder 27 is shown in FIG. 6.
[0067] The holder has a plurality of holding portions 33 for
holding a plurality of the chip-like electronic parts 21. Each
chip-like electronic part 21 has at least two outer surfaces facing
outward so that a portion of the central electrode can be applied
thereto. More generally, a portion of the outer surface
corresponding to an arc of at least 180.degree. around the center
axis of the part 21 is exposed. In the example shown, two side
faces 31 and 32, located on opposite sides of edge line 30, are
exposed. Each of the holding portions 33 is preferably provided
with a holding groove 34 for receiving the non-exposed surfaces of
the chip-like electronic part 21. The holding groove 34 has a
contact face 35 against which the non-exposed surfaces 37 and 38 of
the chip-like electronic part 21 rest. Since the chip-like
electronic part 21 has a square cross-section the contact face 35
has a V-like shape.
[0068] The holder 27 is formed, for example, from an elastic body.
The contact face 35 adheres to the chip-like electronic part 21 to
hold it in place. This can be achieved by any suitable means such
as by vacuum sucking.
[0069] Next, as shown in FIG. 7, a groove 40 located in an elastic
paste base 39 is filled with a conductive paste 41 to form a paste
streak 42 (paste extending in a shape of a streak). The chip-like
electronic part 21 is held by the holder 27 in an orientation
wherein the paste streak 42 extends orthogonal to the central axis
of the chip-like electronic part 21 and is positioned at a location
corresponding to the middle of the chip-like electronic part 21.
The holder 27 and the paste base 39 are brought into contact with
one another so that the paste base 39 is deformed and presses
against the outer side surfaces 31, 32 of the chip-like electronic
part 21 and conductive paste 41 from the paste streak 42 is applied
to the side surfaces 31, 32 as shown in phantom in FIG. 7.
[0070] In accordance with this step of the process, a band of
conductive paste 41 is provided on the contiguous side faces 31 and
32 but is not applied to the opposite side faces 37 and 28.
Similarly, the conductive paste does not stain the holder 27. The
resultant band of conductive paste 41 is shown in FIG. 13 as band
41a.
[0071] Two non-limiting alternative process of forming the
conductive paste streak 42 are shown in FIGS. 8 and 9.
[0072] In the embodiment of FIG. 8, the conductive paste 41 is
applied to the flat face of the paste base 43 which may be an
elastic or rigid body. If it is a rigid body, it may be necessary
to rotate the part 21 back and forth about its longitudinal axis to
bring the two opposite side faces 31 and 32 into contact with the
paste streak 42. The conductive paste 41 may be built up onto the
surface of the paste base 43 by printing or the like to form a
conductive paste streak 42.
[0073] In the embodiment of FIG. 9, a supply of conductive paste 41
is arranged on one side of a plate 45 having an elongated slit 44
(which may be rigid or deformable) and is extruded through the slit
44 to form a conductive paste streak 42.
[0074] The paste base 39 of FIG. 7 and the paste base 43 of FIG. 8
are preferably deformed more easily than the elastic body
constituting the holder 27 to avoid undesirable deformation of the
holder 27.
[0075] Once the conductive paste 41 has been applied to the faces
31, 32 of the chip-like electronic part 21, the part 21 is either
transferred to a second holder or removed from the first holder,
rotated, and returned thereto, for application of conductive paste
to the remaining two side faces 37 and 38. The second holder may
have a structure similar or identical to that of the holder 27. In
any event, the chip-like electronic part 21 is held by the holder
so that the coated side surfaces 31, 32 face inwardly (are not
exposed) and the remaining faces 37, 38 face outwardly as shown in
FIG. 12. In the preferred embodiment, two substantially similar
holders are used and the transfer takes place by positioning the
two holders opposite one another and simultaneously transferring
the plurality of the chip-like electronic parts 21 from the first
holder to the second holder in a single motion.
[0076] In the case where the second holder is used as described
above, it is preferable to use a holder 27a shown in FIG. 10
through FIG. 12. Holder 27a is provided with a recess portion 46
which accommodates the band of conductive paste 41 applied to the
side surfaces 31, 32 and prevents the holder 27a from being brought
into contact with the conductive paste 41 on these sides. This
prevents the band of conductive paste 41 from being peeled off and
the holder 27a from being stained by the conductive paste 41. The
width of the recess portion 46 is preferably wider than that of the
band of conductive paste 41. The structure of the holder 27a is
otherwise substantially similar to that of the holder 27 and a
further explanation will not be provided. This holder may be used
with any of the foregoing paste bases, for example, that of FIG.
7.
[0077] As shown in FIGS. 11 and 12, the holder 27a holds the
chip-like electronic part 21 with the uncoated side surfaces 37, 28
facing outwardly and with the band of conductive paste 41 located
on side surfaces 31, 32 positioned inside of the recess portion 46.
The conductive paste 41 is then applied to the exposed side
surfaces 37, 38 in accordance with any of the process described
above. When this process is completed, the band of conductive paste
41 will extend around the entire periphery of the chip-like
electronic part as illustrated in FIG. 13 without the formation of
build up (e.g. overlap) areas in the central portions of the side
faces 31, 32, 37 and 38 such as are created when using the prior
art processes. Compare FIGS. 13 and 20. By curing the conductive
pastes 41a and 41b, the desired central electrode 24 as shown by
FIG. 1 is formed.
[0078] To form the end electrodes 22 and 23 at respective end
portions of the chip-like electronic part 21, the end portion of
the chip-like electronic part 21 may be dipped into a tank of
conductive paste and thereafter, the conductive paste is cured. It
is preferable that the curing operation be carried out
simultaneously with the curing operation for forming the central
electrode 24 mentioned above.
[0079] When forming the central electrode 24 on a chip-like
electronic part 21b having a rectangular cross section, a holder
27b (FIG. 14) is used. This holder has a holding groove 34b whose
shape corresponds to that of the chip-like electronic part 21b.
More particularly, the holding groove 34b has the shaped right
triangle dividing the cross sectional profile of the chip-like
electronic part 21a diagonally. The structure and operation of
holder 27b is otherwise the same as holder 27 and no further
description will be provided.
[0080] In the foregoing embodiments, the end electrodes 22, 23 are
preferably formed by dipping. However, they can also be formed by,
for example, using a process similar to that used to form central
electrode 24 as shown in FIGS. 15 and 16.
[0081] As shown in FIG. 15, three conductive paste streaks 42a, 42b
and 42c are formed on an elastic paste base 43 at areas
corresponding to the central portion and end portions of the
chip-like electronic part 21. In the embodiment shown, the
conductive paste streaks 42a, 42b and 42c, are placed on a flat
surface of the paste base 43. Other processes such as that of FIGS.
7 and 9 can also be used. Whichever process is used, the holder 27
and paste base 43 are moved toward one another to bring the
conductive paste streaks 42a, 42b and 42c into contract with the
side surfaces 31, 32 of the chip-like electronic part 21 while the
paste base 43 is deformed to surround those side surfaces. As a
result, as shown in FIG. 16A, band of conductive paste 41 is
applied to the outer surfaces 31, 32 as well as one half of the end
surfaces of the chip-like electronic part 21.
[0082] The chip-like electronic part 21 is then held in an
orientation wherein the two uncoated side faces 37 and 38 are
exposed and a coating of conductive paste 41 is applied to the side
surfaces 37, 38 as well as the remaining end surfaces using the
foregoing process to form three bands of conductive paste 41
extending around the entire periphery of the part 21 and
corresponding to a central electrode 24 and two end electrodes 22
and 23.
[0083] As shown in FIG. 16B, the conductive paste 41 is applied to
all areas where end electrodes 22 and 23 and the central electrode
24 should be formed. Overlapping portions X are formed in the end
electrodes 22, 23 and the central electrode 24 as a result of the
conductive paste 41 being applied as described above. Finally, the
conductive paste 41 is cured, thereby forming the end electrodes
22, 23 and the central electrode 24. The overlapping portions X of
the conductive paste are swollen after the conductive paste 41 as
has been cured.
[0084] If desired, the foregoing process may be used to form just
the end electrodes 22, 23 of the chip-like electronic part 21 in
which case only the conductive paste streaks 42b and 42c (FIG. 15)
are formed on the paste base.
[0085] In lieu of the foregoing holders which contain a holding
groove, the holder 27c of FIG. 17 may be used (indeed any suitable
holder may be used to carry out the process of the present
invention). Holder 27c has a holding hole 47 for holding the
chip-like electronic part in the required orientation. At least an
inner peripheral face portion 48 of the holding hole 47 is elastic.
The chip-like electronic part 21 is held in a desired orientation
by elastically sandwiching opposite end faces of the chip-like
electronic part 21 extending perpendicular to the hole 47.
[0086] In the foregoing embodiments, the process of the present
invention is applied to a chip-like electronic part 21 or 21a in
the shape of a quadrangular prism. However, the process of the
present invention can be used with other chip-like electronic parts
such as those having a polygonal or a cylindrical shape. In the
case of the chip-like electronic part having a cylindrical shape,
one of generators present on the outer surface constitutes one edge
line. Additionally, the present invention is applicable to a
chip-like electronic part other than the three terminal
capacitor.
[0087] The present invention may be embodied in other specific
forms without departing from the spirit or essential attributes
thereof and, accordingly, reference should be made to the appended
claims, rather than to the foregoing specification, as indicating
the scope of the invention.
* * * * *