Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE IN~7ENTION
Field of the Invention:
This invention relates to an electronic circuit arrangement
mounted on a printed circuit board, and more particularly to an
electronic circuit arrangement in which leadless electronic
circuit parts are arranged on a printed circuit board in high
integration density.
Description of the Prior Art
Leadless electronic circuit parts are ~nown which consist
``~ of cylindrical bodies of ceramics with metal caps fitted to
each of the ends of the cylindrical body of ceramics. For example,
the leadless electronic circuit part may be a resistor in which
a carbon film is formed on the cylindrical body o~ ceramic, and an
insulating film is additionally formed over the carbon film.
Adhesive resin is applied to a predetermined position between two
conductive patterns on a printed circuit board and the leadless
electronic circuit part is attached to the printed circuit board
~'~ith the adhesive resin, and it is then dipped into a solder bath.
The metal caps of the leadless electronic circuit part will be
attached to the conductive patterns by the solder from the bath
so as to electrically connect the conductive patterns through
the component.
; ~ However~ when there is a small distance between two
adjacent leadless electronic circuit parts is small, it is ~ossible
for the s~ace between the adjacent metal caps to be filled with
solder which will short out the adjacent conductive patterns.
Thus, to prevent this, the distance between two adjacent leadless
electronic circuit parts must be larger than a predetermined
length. This limits the integration density of leadless electronic
circuit parts made according to the prior art.
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SUMMARY OF THE INVENTI~N
Accordingly, it is an object of this invention to
provide an electronic circuit arrangement in which the integration
density can be increased.
Another object of this invention is to provide an
electronic circuit arrangement of small size.
A further object o~ this invention is to provide an
electronic circuit arrangement by which the degrees of freedom
for circuit design can be increased.
In accordance with an aspect of this invention, there
is provided an electronic circuit arranaemen-t in which leadless
electronic circuit parts consisting of cylindrical or prismatic
bodies and electrodes attached to both ends o~ the body are
mounted on a printed circuit board, and electrodes of adjacent
leadless electronic circuit parts are connected directly to each
other through solder rather than through a conductive pattern.
Other objects, features, and advantages of the present
;nvention will be apparent from the following description taken
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of one example of a leadless
electronic circuit part;
Fig. 2 is a partially broken away cross-section view
of an electronic circuit arrangement mounted on a printed circuit
board according to the prior art;
Fig. 3 is a partially broken away perspective view of
the electronic circuit arrangement of Fig. 2 in which the
relationship o~ the electrodes of the leadless electronic circuit
part, the conductive patterns and the solder are illustrated~
Fig. 4 is a partial:ly broken away cross-sectional view
of an electronic circuit arrangement mounted on a printed circuit
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board according to a first embodiment of this invention;
;Fig. 5 is a partially broken away plan view of an
electronic circuit arrangement mounted on a printed circuit board
accordin~ to a second embodiment of this invention; and
Fig. 6 is a partially broken away plan view of an
;electronic circuit arrangement mounted on a printed circuit
board according to a third embodiment of this invention.
- DESCRIPTION OF THE PREF:E:R~ED EMBODIMENTS
A conventional electronic circuit arrangement mounted
on a printed circuit board is shown in Figs. 1, 2 and 3.
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A leadless electronic circuit part 4 such as shown in
Fig. 1 is known. The leadless electronic circuit part 4 has
a cylindrical body 1 of ceramics which covered at both ends with
metal caps 2 and 3. The leadless electronic circuit part 4
maybe, for example, a resistor, a capacitor or a jumper. When
the leadless electronic circuit part 4 is a resistor, a carbon
film is formed on the circu~ferential surface of the cylindrical
body 1. ~hen the leadless electronic circuit part 4 is a capacitor,
the cylindrical body 1 is hollow, and conductive films are formed
on the inner and outer circumferential surfaces of the cylindrical
body 1. When the leadless electronic circuit part 4 is a jumper,
a conductive film is formed on the circumferential surface of the
cylindrical body 1, or a metal rod is machined so as to have the
shape shown in Fig. 1. The exposed portions of the cylindrical
body 1 which is not covered with the metal caps 2 and 3, is
coated with an insulating material.
The leadless electronic circuit parts are mounted on a
printed circuit board 5 in the manner shown in Fig. 2 and Fig. 3.
First, during the mounting operation, adhesive resin 10 is applied
to predetermined positions between copper patterns 6 and 7, and
8 and 9 formed in the printed circuit board 5 on solder resistant
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layers 11 and 13. Next, leadless electronic circuit parts 4a
and 4b are mounted on the printed circuit board 5 such that the
central portions of the leadless electronic circuit ~arts 4a and
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4b are attached to the solder-resistive layers 11 and 13 with the
adhesive rèsin 10. Reference numeral 12 also represents a solder-
resistive layer. Thus, the leadless electronic circuit parts
4a and 4b are provisionally attached to the printed circuit
board 5. Next, the leadless electronlc circuit parts ~a and 4_
together with the printed circuit board 5 are dipped into a
solder bath, and then ta];en out from the solder bath. This causes
the caps 2 and 3 to be fixed to the patterns 6 and 8, and 7 and
9, by solder 14 and 16, and 15 and 17, respectively, as
shown in Fig. 3. The patterns 6 and 7 are electrically connected
to each other through the leadless electronic Part 4a. The
patterns 8 and 9 are electronically connected to each other through
the leadless electronic part 4b.
The leadless electronic circuit part 4 has a small si~e
and it can be easily handled. The circuit parts 4 are
automatically mounted on the printed circuit board 5 by an
automatic mounting apparatus. Many leadless electronic circuit
parts 4 can be mounted on a printed circuit board with high
integration density.
However, when the leadless electronic circuit parts
4a and 4b are mounted on the printed circuit board 5 such that
the distance Ql,as shown in Fig. 2, between them is too small,
it is possible that the space between them will be filled with
solder, and that the solder 15 and 16 will become one body, which
results in electrical shorting between the patterns 7 and 8. In
order to prevent this, the distance Ql must be larger than a
predetermined length. When numerous leadless electronic circuit
parts are mounted on one printed circuit board, this will cause the
integration density to be limited and this prevents the circuit
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from being smaller than a certain size.
A first embodiment of this invention is shown in Fig.
4. Three leadless electronic parts 4a, 4b and 4c are
electrically connecte~ in series with each other. ~ metal cap
2a of the first leadless electronic circuit part 4a is
connected to a first conductive pattern 18 by solder 19 and the
metal cap 3a of the first leadless electronic circuit part 4a
is directly connected to a metal cap 2b of a second leadless
electronic circuit part 4b by solder 20. A metal cap 3_ of the
second leadless electronic circuit part 4_ is directly connected
to a metal cap 2c of a third leadless electronic circuit part 4c
by solder 21, and a metal cap 3c of the third leadless electronic
circuit part 4c is connected to a second electrical pattern 23
by solder 22. Thus, the 23 by solder 22. Thus, the connection
between members 4a, 4b and 4c is through the solder and not
through a conductive path on the board. The metal caps 2a, 2b,
2c, 3a, 3b and 3c are covered with solders 19 to 22 as shown in
Fig. 3. Thus, the series connection of the circuit parts 4a, 4b
and 4c is made between the first and second electrical conductive
patterns 18 and 23.
The circuit parts 4a, 4b and 4c can be mounted on the
printed circuit board 5 in the same manner as described with
reference to Figs. 1, 2 and 3. During the mounting operation,
adhesive resin 10 is applied to predetermined positions of the
solder resistant layer 11 by a screen printing method. The circuit
parts 4a, 4b and 4c are provisionally attached to the printed
circuit board 5 by adhesive resin 10. The distance Q2 between
the adjacent circuit parts 4a and 4_, and 4_ and 4c can be
smaller than the distance ~1 of the prior art arrangement of
Fig. 2 and the spaces between the metal caps 3a and 2b, and 3_
and 2c are filled with solder 20 and 21. For example, if the
distance Ql is 3.5mm, the distance Q2 may be smaller than 2mm.
The provisionally attached circuit parts 4a, 4b and 4c are then
dipped into the solder bath together with the printed circuit
board 5 which will cause the circuit parts 4a, 4b and 4c to be
attached to the printed circuit board 5 by the solder 19, 20, 21
and 22.
A second embodiment of this invention is shown in Fig. 5.
Four leadless electronic circuit ~arts 4 are directly connected
in series with each other by solder 24, in the direction shown
by the arrow X on Fig. 5. Two leadless electronic circuit parts
4 are directly connected in series with each other by solder 24,
in the direction shown by the arrow Y on Fig. 5. The arrow Y is
orthogonal to the arrow X. The X series of the circuit parts 4 are
directly connected with the Y-series of the circuit parts 4 by
solder 24. Thus, the series of the six circuit parts 4 are
arranged between conductive patterns 25 and 26. Cross patterns
of conductive layers 27 extend across the circuit parts 4. The
c'ircuit parts 4 are insulated from the cross patterns 27 by the
solder-resistive layer 11 and adhesive resin 10.
A third embodiment of this invention is shown in Fig. 6.
In this embodiment, leadless electronic circuit parts 4 are
connected in the shape of the letter T, in the X and Y directions.
The three leadless electronic circuit parts 4 are connected in
series with each other through solder 32, in the X direction.
Thus, conductive patterns 28, 30 and 31 are electricalLy
connected to each other. The two leadless electronic circuit parts
4 are connected in series with each other, in the Y direction.
Thus, conductive patterns 29 and 30 are electrically connected to
each other. One series o~ the three leadless electronic circuit
parts 4 and another series of the two leadless electronic circuit
parts 4 are connected to each other through solder 32 at the position
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of conductive pattern 30. Thus, the conductive patterns 28, 29,
30 and 31 are electrically interconnected to each other through
the leadless electronic circuit parts 4.
Leadless electronic circuit parts 4 can be arranged '
in an arbitrary shape in the X and Y direction by an automatic
mounting apparatus~ Series circuits, parallel circuits and a
series-parallel circuits of the same leadless electronic circuit
parts or of different leadless electronic circuit parts (resistors,
capacitors and so on), can be arbitrarily designed into any
desired arrangement of conductive patterns.
According to this invention, as above described, plural
leadless electronic circuit parts can be arranged in close
vicinity to each other. Accordingly, the integration density
can be increased. The degree of freedom for circuit design on the
same printed circuit board can be greatly increased.
For example, in the above described embodiment, the
leadless electronic circuit part 4 is cylindrical. However, it
may be of the chip type in which metal caps are fitted to both
end portions of a prismatic body.
Although the illustrative embodiments of the invention
have been described in detail herein with reference to the
accompanying drawings, it is to be understood that the invention
is not limited to those precise embodiments, and that various
chan~es and modifications can be effected therein by one skilled
in the art without departing ~rom the scope and spirit of the
invention as defined in the appended claims.
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