CA1140680A

CA1140680A - Electronic circuit arrangement mounted on printed circuit board

Info

Publication number: CA1140680A
Application number: CA000342057A
Authority: CA
Inventors: Mitsuo Ohsawa
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1978-12-18
Filing date: 1979-12-17
Publication date: 1983-02-01
Also published as: DE2950450A1; JPS5582487A; IT7942915A0; GB2037489B; GB2037489A; JPS6149838B2; IT1193457B; NL7909108A

Abstract

ABSTRACT OF THE DISCLOSURE

In an electronic circuit arrangement in which leadless electronic circuit parts consisting of cylindrical bodies with electrodes attached to both-ends of the body are mounted on a printed circuit board with the electrodes of adjacent leadless electronic circuit parts are connected directly to each other through axially arranged solder rather than through a conductive pattern.

Description

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.
r 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 . . , 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 ~ ~()6~

., 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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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An electronic circuit arrangement comprising, a printed circuit board with at least first and second spaced apart planar conductive patterns formed on one side thereof, a plurality of leadless electronic components with relatively long longitudinal dimensions and with metal caps attached to opposite ends, at least first and second said electronic components attached adjacent to each other on said printed circuit board with the metal cap of said first end of said first electronic component connected by solder to said first conductive pattern, the metal caps of the second end of said first electronic component and the first end of said second electronic component connected together by solder, the metal cap of the second end of said second electronic component connected by solder to said second conductive pattern, and the spacing between said metal caps of the second end of said first electronic component and the first end of said second electronic component spaced closely together such that solder substantially fills the space therebetween, and wherein said first and second electronic components components connected to said printed circuit board by an adhesive resin.

2. An electronic circuit arrangement according to claim 1 wherein said first and second electronic components are mounted end to end.

3. An electronic circuit arrangement according to claim 2 wherein said first and second electronic components are mounted such that their longitudinal axes make an angle other than zero degrees.

4. An electronic circuit arrangement according to claim 3 including at least one additional leadless electronic component with a relatively long longitudinal dimension and with metal caps on opposite ends attached to said printed circuit board with the cap of its first end connected by solder to the caps of the second end of said first component and the first end of said second component and a third conductive pattern formed on said printed circuit and the metal cap of the second end of said additional leadless component connected by solder thereto.

5. An electronic circuit arrangement according to claim 1 wherein at least one of said electronic components is a resistor.

6. An electronic circuit arrangement according to claim 1 wherein at least one of said electronic components is a capacitor.