Feed-through type multilayer capacitor

A feed-through type multilayer capacitor having a layered structure in which two dielectric sheets, each having a through electrode of approximately constant width formed on its outer surface, are disposed so as to have the same direction of said through electrode; and additional dielectric sheets having earth electrodes thereon are formed respectively on the top side and the bottom side of the dielectric sheets having through electrodes, so that said earth electrodes formed on the outer surfaces of these dielectric sheets will cross said through electrodes, with the result that the respective crossing portions of each through electrode and each earth electrode oppositely face each other with the dielectric sheet therebetween, to form electrostatic capacitance.

BACKGROUND OF THE INVENTION 
The present invention relates to a feed-through type multilayer capacitor 
having a through electrode and an earth electrode on the outer surfaces of 
dielectric sheets to be laminated to form one block of layered structure. 
As shown in a perspective view, a longitudinally sectional view and an 
exploded perspective view of FIG. 1, FIG. 2 and FIG. 3, respectively, a 
conventional feed-through type multilayer capacitor has been constructed 
by laminating a first dielectric sheet 2 provided with a through electrode 
1 thereon, a pair of second dielectric sheets 4, 6 provided with earth 
electrodes 3, 5 thereon, and an insulating sheet 7; and providing 
terminals 9, 10, 11 for the electrodes 1, 3, 5 on the outer surface of the 
sheets; thereby forming one block 8 of square pillar type having 
approximately constant dimensions. The pair of second dielectric sheets 4, 
6 is laminated on the top and bottom faces of the first dielectric sheet 2 
respectively such that the earth electrodes 3, 5 are placed traversely in 
a direction orthogonal to the line of the through electrode 1, and the 
insulating sheet 7 is mounted on the top face of the second dielectric 
sheet 4. Accordingly, sheets 7, 4, 2, 6 are laminated in that 
order to form a feed-through type multilayer capacitor comprising one block 
8 providing with a pair of through electrode terminals 9, 10 of cover type 
connected with the through electrode 1 on opposite sides of the block 8 
and an earth electrode terminal 11 connected with a pair of earth 
electrodes 3, 5, the terminal 11 having the form of a ring around the 
intermediate portion of the block 8. Thus, an electrostatic capacitance is 
provided between the through electrode 1 and earth electrodes 3, 5, which 
are arranged transverse to each other and sandwich the corresponding 
dielectric sheet 4 or 2 therebetween in the direction of thickness. Both 
ends of the through electrode 1 are respectively drawn out to the through 
electrode terminals 9, 10 formed on both the end faces of the block 8 of 
the dielectric sheets 2, 4, 6 and the insulating sheet 7. The earth 
electrodes 3, 5 are drawn out to the earth electrode terminal 11 formed 
between these through electrode terminals 9, 10. The electrostatic 
capacitance is formed between the earth electrodes 3, 5 and a crossing 
portion 12 of the through electrode 1 disposed between the earth 
electrodes 3, 5. 
In a feed-through type multilayer capacitor of such construction as 
described hereinabove, the thickness of the through electrode 1 is 
normally as extremely thin as several .mu.m and the resistance value R of 
the through electrode 1 connected between the through electrode terminals 
9 and 10 becomes high. Therefore, when the energizing current of the 
through electrode 1 becomes large, the through electrode 1 is heated and 
becomes high enough to melt the solder, which is used to solder the 
through electrode terminals 9, 10 of the feed-through type multilayer 
capacitor and the earth electrode terminal 11 thereof, to the patterns of 
the printed circuit board (not shown). The repeated heating operation 
causes stress among the through electrode terminals 9, 10, the earth 
electrode terminal 11 and the other portions so as to cause cracks in the 
dielectric sheets 2, 4, 6 or the insulating sheets 7. 
SUMMARY OF THE INVENTION 
Accordingly, an important object of the present invention is to provide an 
improved feed-through type multilayer capacitor, which is free from the 
above-described problems of a conventional capacitor, and can handle 
larger energization current in the through electrode while exhibiting less 
heating. 
Another important object of the present invention is to provide a 
feed-through type multilayer capacitor of the above-described type which 
has less electric field concentration applied to an electrode provided on 
the outer surface of the dielectric sheet to be laminated to form one 
block having a layered structure, thereby to improve the withstand voltage 
characteristics thereof. 
In accomplishing these and other objects, according to the present 
invention, there is provided a feed-through type multilayer capacitor 
where through electrodes are formed respectively on two dielectric sheets. 
As these through electrodes are connected at the ends to each other and in 
parallel relation, the resistance values between both ends of the through 
electrodes become smaller.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
Before the description embodiments of the present invention proceeds, it is 
to be noted that like parts are designated by like reference numerals 
throughout the accompanying drawings. 
Referring now to the drawings, there is shown in FIG. 4, FIG. 5 and FIG. 6, 
according to a first embodiment of the present invention, a feed-through 
type multilayer capacitor comprising, in combination , a pair of 
dielectric sheets 2a, 2b having through electrodes 1a, 1b, a pair of 
dielectric sheets 4, 6 having earth electrodes 3, 5, an insulating sheet 
7, and terminals 9, 10, 11 connected with said through electrodes 1a, 1b 
and earth electrodes 3, 5. The sheets are laminated in piling up as one 
block 8 in order of 7, 4, 2a, 2b, 6 from top to bottom. The through 
electrodes 1a, 1b are placed in a direction approximately orthogonal to 
the earth electrodes 3, 5 and the terminals 9, 10, 11 are provided on the 
outer surface of the block 8. The capacitor has the pair of dielectric 
sheets 2a, 2b provided with the through electrodes 1a, 1b thereon to be 
placed in parallel to each other and disposed between the pair of 
dielectric sheets 4 and 6, which are corresponding to the sheets 4, 6 of 
the conventional feed-through type multilayer capacitor described in FIGS. 
1 to 3. Thus, 
a pair of electrostatic capacitances are provided between the earth 
electrodes 3, 5 and crossing portions of the through electrodes 1a, 1b 
disposed between the earth electrodes 3, 5. The dielectric sheet 2a has a 
through electrode 1a formed on its major face, while the dielectric sheet 
2b has a through electrode 1b formed on its major face. Both ends of the 
through electrode 1a are respectively connected with Kthrough electrode 
terminals 9, 10. Both ends of the through electrode 1b are respectively 
connected with through electrode terminals 9, 10. Accordingly, the inside 
electrodes of the capacitor disposed within the block 8 consist of two 
pairs of through electrodes and earth electrodes, while the outside 
electrodes disposed on the outer surface of the block 8 consist of a pair 
of through electrode terminals connected to the pair of through electrodes 
and one earth electrode terminal connected to the pair of earth 
electrodes. When a current flowing between the through electrode terminals 
9, 10 is equal to that of the conventional feed-through type multilayer 
capacitor, the calorific value of the first embodiment of the present 
invention is one half that of the conventional one. When the calorific 
value is one half, thermal stress which is applied to the dielectric 
sheets 2a, 2b, 4, 6 and an insulating sheet 7 of the first embodiment is 
reduced to prevent cracks from being caused. 
FIG. 14(a) is a simplified longitudinal sectional view of a capacitor in 
accordance with the present invention. FIG. 14(b) shows a simplified 
longitudinal sectional view of the conventional capacitor for comparison 
therebetween. In the conventional capacitor, the electric field is 
concentrated on one electrode to cause the withstand-voltage 
characteristics to deteriorate. In the capacitor of the present invention, 
the electric-field concentration is divided between two electrodes and is 
thereby halved, thus doubling the withstand-voltage characteristics of the 
capacitor. 
FIGS. 7 through 9 show a second embodiment of the present invention, 
wherein the pattern of the electrode 3, 5 is formed in the shape of a 
cross to increase the area of the electrode, the external terminal of the 
earth is halved by the top, bottom faces of the unit. Also, the outside 
terminal 11 of earth electrodes disposed on the outer surface of the block 
8 is divided in two by cutting off the central portions thereof disposed 
on the outer surface of the insulating sheet 7 and dielectric sheet 6 in 
order to reduce the area amount of the outside terminal 11 facing directly 
to the earth electrodes 3, 5 of the sheets 7, 6 through the sheets 7, 6, 
thereby to render to improve the characteristic of withstand voltage of 
the capacitor. 
FIGS. 10 through 12 show, according to a third embodiment of the present 
invention, a feed-through type multilayer capacitor comprising, in 
combination of, a pair of dielectric sheets 2a, 2b having through 
electrodes 1a, 1b, a pair of dielectric sheets 4, 6 having earth 
electrodes 3, 5, a further pair of dielectric sheets 13, 15 having through 
electrodes 14, 16, fours pairs of insulating sheets 7, and terminals 9, 
10, 11 connected with said through electrodes 1a, 1b, 14, 16 and earth 
electrodes 3, 5, the sheets being laminated in piling up in order of 7, 7, 
13, 7, 4, 7, 2a, 2b, 7, 6, 7, 15, 7, 7 from top to below to form one block 
8 and providing the terminals 9, 10, 11 on the outer surface of the block 
8. Each one of insulating sheets 7 is inserted between each pair of 
dielectric sheets 13 and 4, 4 and 2a, 2b and 6, 6 and 15, and each sets of 
two insulating sheets 7 are provided at outsides of the top and below 
dielectric sheets 13, 15, thereby to render to improve the characteristic 
of withstand voltage of the capacitances. The capacitor has the pair of 
dielectric sheets 2a, 2b both disposed between the pair of dielectric 
sheets 4, 6 under placing the through electrodes 1a, 1b of the dielectric 
sheets 2a, 2b in parallel with each other but in a direction orthogonal to 
the earth electrodes 3, 5 of the dielectric sheets 4, 6 in order to 
provide a pair of electrostatic capacitances among the earth electrodes 3, 
5 and crossing portions of the through electrodes 1a, 1b disposed between 
the earth electrodes 3, 5. Also, the capacitor has the further pair of 
dielectric sheets 13, 15 each disposed between the corresponding 
dielectric sheet 4 or 6 of earth electrode 3 or 5 having an insulating 
sheet 7 and the pair of insulating sheets 7, 7 disposed at the outside of 
the further pair of dielectric sheets 13, 15 on which the outer surface is 
provided with the terminals 9, 10, 11 under placing the through electrodes 
14, 16 of the further dielectric sheets 13, 15 in parallel to the through 
electrodes 1a, 1b of the dielectric sheets 2a, 2b, the pair of terminals 
9, 10 for through electrodes being connected to the both sides of the 
through electrodes 1a, 1b 14, 16 of the dielectric sheets 2 a, 2b and the 
further dielectric sheets 13, 15, in order to provide a pair of further 
electrostatic capacitances among the earth electrodes 3, 5, terminal 11 
and crossing portions of the through electrodes 14, 16 disposed between 
the earth electrodes 3, 5 and terminal 11. Accordingly, with the above 
arrangement having electrostatic capacitances, the electrostatic 
capacitances and current capacity thereof can be increased in amount in 
comparison with those of the first embodiment. It is to be noted that, in 
the various capacitors, since the electrostatic capacitance to be formed 
between the through electrode 14 or 16 and the terminal 11 is obtained 
through a plurality of insulating sheets 7, the electrostatic capacitance 
becomes extremely small in the practical use without causing troubles of 
withstand voltage thereof. The insulating sheets provided between the 
dielectric sheets and, also, at the outsides of the dielectric sheets 13, 
15 may be omitted except for one disposed at the outside of the further 
dielectric sheet 13 or can be replaced merely by dielectric sheets having 
no electrode thereon, in accordance with the characteristic of withstand 
voltage of the capacitor. 
FIG. 13 shows a modified example of the third embodiment, wherein two 
dielectric line sheets 13, 18 or 15, 19 having through electrodes 14, 17 
or 16, 20 are interposed between the earth electrode 3 or 5 of the 
dielectric sheets 4 or 6 and the external terminal 11 to assemble layers 
of nine in all to ensure the withstand voltage of the through electrode 14 
or 16 of the further dielectric sheet 13 or 15. Therefore, the desired 
object may be achieved by the simple construction. Accordingly, in the 
third embodiment the dielectric sheets 18, 19 having through electrodes 
17, 20 thereon are added as to form a couple with the dielectric sheets 
13, 15 having through electrodes 14, 16 of the second embodiment, thereby 
to render to improve the characteristic of withstand voltage of the 
capacitor. 
FIGS. 15 through 17 show a feed-through type multilayer capacitor of the 
fourth embodiment of the present invention, wherein there provide a pair 
of dielectric sheets 4a, 4b and 6a, 6b having earth electrodes 3a, 3b and 
5a, 5b in place of each one of the dielectric sheets 4, 6 having earth 
electrodes 3, 5 in the second embodiment of FIGS. 10 through 12 in order 
to make an enforcement of withstand voltage of the capacitor for use in 
high voltage. In the fourth embodiment, sixteen sheets are laminated in 
piling up in order of 7, 7, 13, 7, 4a, 4b, 7, 2a, 2b, 7, 6a, 6b, 7, 15, 7, 
7, from top to below to form one unit, and three terminals 9, 10, 11 are 
provided on the outer surface of the block 8. In other words, the pair of 
earth electrodes are provided as well as the through electrodes in order 
to eliminate the problem of withstand voltage to be raised in the third 
embodiment. 
FIG. 18 shows a modified example of pattern for an electrode 21 to be 
provided on the dielectric sheet of the capacity and having a front view 
of I-shape in order to ensure the connection of the through electrode. 
In addition, there may be easily provided a feed-through multilayer 
capacitor of the construction having a pair of earth electrodes and a pair 
of through electrodes in combination of capacitors of the third and fourth 
embodiments. 
According to the present invention, through type electrodes are formed 
respectively in two dielectric sheets in a feed-through type multilayer 
capacitor so that these through electrodes are adapted to be connected in 
parallel. Therefore, the sectional area of the through electrode becomes 
larger and the resistance value becomes lower. Accordingly, according to 
the present invention, the energization current may be doubled and the 
heating may be almost halved as compared with the conventional one. In 
addition, the reduction in the calorific value prevents the repeated 
heating and cooling operations from causing cracks or the like in the 
dielectric sheets. Also, the electric field concentration on the electrode 
can be almost halved to improve the withstand voltage characteristics. 
Although embodiments of the present invention have been described by way of 
example with reference to the accompanying drawings, it is to be noted 
here that various changes and modifications will be apparent to those 
skilled in the art. Therefore, unless such changes and modifications 
depart from the scope of the present invention, as defined in the claims, 
they should be construed as being included therein.