Multilayer through type capacitor array

The invention decreases crosstalk due to capacitive coupling between through type capacitor elements in a multilayer through type capacitor array. On dielectric sheets between electrodes, which constitute a multi capacitor array, through-holes filled with conductive materials are formed, where a central conductor is not present. By electrically connecting conductive materials filled in the through-holes, electrostatic shielding is provided between the through type capacitor elements. Electrical connection is achieved through conductive layers formed outside or inside the through type capacitor elements.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a ceramic multilayer through type 
capacitor array, comprising at least two or more multilayer through type 
capacitors in a ceramic chip. 
With rapid growth of various types of electronic devices and equipment, 
these devices and equipment are increasingly produced in miniaturized and 
lightweight design. In particular, miniaturization and lightweight design 
are being used in electronic devices and equipment of portable type such 
as camera-integrated video tape recorders, portable telephone sets, note 
type personal computers, palmtop computers, etc. 
With the propagation of miniaturization and lightweight design of the 
electronic devices and equipment, electronic parts are also increasingly 
produced in miniaturized and lightweight designs. The means for mounting 
electronic parts are also changing from conventional means for inserting 
and soldering electronic parts and pins used in through-hole on 
conventional type printed circuit board to surface mounting technology 
(SMT) for mounting and soldering electronic parts on conductive patterns 
provided on printed circuit boards. 
The electronic parts used in SMT are generally called surface mounting 
devices (SMD), and these include semi-conductor parts as well as 
capacitors, resistors, inductors, filters, etc. (Among them, small parts 
such as capacitors and resistors are called chips.) 
Among ceramic chip parts, there are composite parts called capacitor arrays 
and resistor arrays where a plurality of circuit elements, e.g. 
capacitors, resistors, or inductors, are incorporated. A multilayer 
capacitor array, comprising a plurality of ceramic multilayer capacitors, 
is a typical example of multilayer array parts. 
Japanese laid-open publications Nos. 55-80319, 57-206015 and 57-206016 
disclose a multilayer through type capacitor array consisting of 
capacitors, each of which is a through type capacitor. 
To explain the structure of a conventional type multilayer through type 
capacitor array, FIGS. 1a through 1k show a multilayer through type 
capacitor array, which comprises four dielectric layers where four 
multilayer through type capacitor elements are combined together. 
This multilayer through type capacitor array comprises a first dielectric 
sheet 1, a second dielectric sheet 2, a third dielectric sheet 3, and a 
fourth dielectric sheet 4, each designed in rectangular form and laid in 
this order. 
FIGS. 1b, 1d, 1f, and 1h represent cross-sectional views of the dielectric 
sheets of FIG. 1a, 1c, 1e, and 1g along the lines b--b, d--d, f--f, and 
h--h respectively. 
On the first dielectric sheet 1, an internal electrode 5 made of conductive 
material, extended in longitudinal direction of the rectangle and reaching 
the two shorter sides of the rectangle, is provided as shown in FIGS. 1g 
and 1h. On the second dielectric sheet 2, four internal electrodes 6, made 
of conductive material, extended in lateral direction of the rectangle and 
reaching the two longer sides of the rectangle, are provided as shown in 
FIGS. 1e and 1f. On the third dielectric sheet 3, an internal electrode 7 
made of conductive material, extended in longitudinal direction of the 
rectangle and reaching only the shorter sides (similar to the internal 
electrode 5 on the first dielectric sheet 1) is provided. On upper surface 
of the dielectric sheet 3, the dielectric sheet 4 shown in FIGS. 1a and 1b 
having no internal electrode is placed. 
External configuration of the multilayer through type capacitor array with 
the above structure is shown in FIG. 1i, and a cross-sectional view along 
the line j--j is given in FIG. 1j. 
On the internal electrodes 6, four terminal electrodes 8 are formed, which 
are extended partially on mounting surfaces, i.e. upper and lower 
surfaces, by means such as printing. This is done in order to connect each 
of the multilayer through type capacitors, constituting the multilayer 
through type capacitor array, to an external printed circuit pattern. On 
the internal electrodes 5 and 7, two terminal electrodes 9 are formed, 
which are extended partially on mounting surfaces, i.e. upper and lower 
surfaces, by means such as printing in order to connect each of the 
multilayer through type capacitors, constituting the multilayer through 
type capacitor array, to an external printed circuit pattern. 
Electrical connection diagram of the multilayer through type capacitor 
array is shown in FIG. 1k. 
The multilayer through type capacitor array with the above arrangement 
comprises four multilayer through type capacitors, which have internal 
conductors 6 as central conductors and internal conductors 5 and 7 
sandwiching the internal conductors 6 as external conductors. The through 
type capacitor is used by grounding the external conductor. In the 
multilayer through type capacitor array, the internal conductors 5 and 7, 
serving as common external conductors, are grounded by the terminal 
electrode 9. 
The common external conductors 5 and 7 have impedance components. Because 
these impedance components serve as common impedance for four through type 
capacitors, crosstalk occurs via these impedance components. 
In the multilayer through type capacitor array with the above arrangement, 
the distance from the external conductor of the multilayer through type 
capacitor, which uses internal conductors arranged inside as a central 
conductor, to the terminal electrode is longer than the distance from 
external conductor of the multilayer through type capacitor, which uses 
internal conductors arranged outside as a central conductor, to the 
terminal electrode. 
For this reason, the inductance component of the external conductor in the 
multilayer through type capacitor, which uses an internal conductor 
arranged inside as central conductor, is different from the inductance 
component of the external conductor in the multilayer through type 
capacitor, which uses an internal conductor arranged outside as central 
conductor, and this makes electrical characteristics of capacitor array 
non-uniform, although it should be uniform. 
Further, the distance between the multilayer through type capacitors, which 
constitute the multilayer through type capacitor array, is small, and 
multilayer through type capacitor elements are separated only by 
dielectric substances. In addition, central conductors of the adjacent 
multilayer through type capacitor elements are not completely covered by 
external conductors. Thus, capacitive coupling often occurs between the 
adjacent multilayer through type capacitor elements. 
Capacitive coupling, although undesirable, is tolerable when operating 
frequency of the circuit is low. However, in a circuit where the operating 
frequency is over several hundreds of MHz such as portable telephone sets, 
crosstalk can occur between signals which pass through the multilayer 
through type capacitors adjacent to each other, and this often leads to 
undesirable consequences such as a decrease of signal-to-noise ratio or 
malfunction of the device incorporating the multilayer through type 
capacitors in the worst case. 
FIGS. 2a through 2k show a conventional multilayer through type capacitor 
array, which solves the problems of the multilayer through type capacitor 
array of FIGS. 1a through 1k such as the problem due to common impedance 
or the problem of non-uniform electrical characteristics. 
In the multilayer through type capacitor array of FIGS. 1a through 1k, the 
terminal electrodes of the external conductor in each multilayer through 
type capacitor are used in common, while in the multilayer through type 
capacitor array of FIGS. 2a through 2k, a terminal electrode of external 
conductor is provided on each of the multilayer through type capacitors. 
This multilayer through type capacitor array also comprises a first 
dielectric sheet 11, a second dielectric sheet 12, a third dielectric 
sheet 13, and a fourth dielectric sheet 14, each designed in rectangular 
form and laid in that order (similar to the multilayer through type 
capacitor array of FIGS. 1a to 1k). 
FIGS. 2b, 2d, 2f and 2h each represents a cross-sectional view of the 
dielectric sheets 11, 12, 13 and 14 of 2a, 2c, 2e and 2g respectively 
along the lines b--b, d--d, f--f and h--h. 
On the first dielectric sheet 11, three internal terminal electrodes 15 
made of conductive material, extended in the lateral direction of the 
rectangle and reaching the two longer sides of the rectangle, and an 
internal electrode 18 integrated with internal electrodes 15, extended in 
lateral direction of the rectangle and reaching none of the sides of the 
rectangle, are provided as shown in FIGS. 2g and 2h. On the second 
dielectric sheet 12, four internal electrodes 16 made of conductive 
material, extended in lateral direction of the rectangle and reaching the 
two longer sides at which the positions do not correspond to the internal 
electrodes 15, are provided as shown in FIGS. 2e and 2f. On the third 
dielectric sheet 13, three internal terminal electrodes 17 made of 
conductive material, extended in lateral direction of the rectangle and 
reaching the two longer sides, and an internal electrode 19 integrated 
with the internal electrodes 17, extended in lateral direction of the 
rectangle and reaching none of the sides of the rectangle, are provided as 
shown in FIGS. 2c and 2d. On upper surface of the dielectric sheet 13, a 
dielectric sheet 14 having no internal electrodes as shown in FIGS. 2a and 
2b is placed. 
The external configuration of the multilayer through type capacitor array 
with the above arrangement is shown in FIG. 2i, and a cross-sectional view 
along the line j--j is given in FIG. 2j. 
On the internal terminal electrodes 15 and the internal terminal electrodes 
17, three terminal electrodes 21 are provided, which are extended 
partially on mounting surfaces, i.e. upper and lower surfaces, by means 
such as printing. This is done in order to connect each of the multilayer 
through type capacitors, constituting a multilayer through type capacitor 
array, to external printed circuit pattern. On the internal electrodes 16, 
four terminal electrodes 20 are provided, which are extended partially on 
mounting surfaces, i.e. upper and lower surfaces, by means such as 
printing. This is done in order to connect each of the multilayer through 
type capacitors, constituting a multilayer through type capacitor array, 
to an external printed circuit pattern. 
In each of the multilayer through type capacitors, which constitute the 
multilayer through type capacitor array, the internal electrodes 16 are 
used as central conductors, and the internal electrodes 18 and 19 are used 
as external conductors to sandwich the internal electrodes 16. These 
internal electrodes 16 as well as the internal electrodes 18 and 19 
constitute the multilayer through type capacitor. 
In the multilayer through type capacitor array, each of the terminal 
electrodes 15 and 17 are provided to correspond to sparings between the 
internal electrodes 16, serving as central conductors. Because these 
internal terminal electrodes 15 and 17 are grounded, impedance components 
of the external conductors do not provide common impedance even when the 
external conductors 18 and 19 are integrated, and no crosstalk occurs via 
these impedance components. 
Also, the distances between the external conductor and the internal 
terminal electrode in each capacitor, which constitutes the multilayer 
through type capacitor array, are equal. Therefore, in this multilayer 
through type capacitor, inductance component of the external conductor in 
the multilayer through type capacitor, which uses the internal conductor 
arranged inside as central conductor, is equal to inductance component of 
the external conductor in the multilayer through type capacitor, which 
uses the internal conductor arranged outside as central conductor. Thus, 
the problem which makes characteristics of the capacitors of the capacitor 
array non-uniform, does not occur. 
However, because three terminal electrodes 21 connected to external 
electrodes are provided between four terminal electrodes 20 connected to 
central electrode, the structure of the terminal electrodes are 
complicated, and it is difficult to miniaturize the multilayer through 
type capacitor array. Also, there are difficulties in manufacturing and 
mounting because spacings between the terminal electrodes are small. 
Because spacings between the multilayer through type capacitor elements 
provided inside are small, the multilayer through type capacitor elements 
are adjacent to each other via dielectric substances, and central 
conductors of the multilayer through type capacitor elements adjacent to 
each other are not completely covered with the external conductors. For 
this reason, serious problems, such as crosstalk due to capacitive 
coupling between the adjacent multilayer through type capacitor elements, 
decrease of signal-to-noise ratio, or malfunction of devices incorporating 
the multilayer through type capacitors are not solved. 
An electrical connection diagram of the multilayer through type capacitor 
array is shown in FIG. 2k. 
SUMMARY OF THE INVENTION 
To solve the above problems, it is an object of the present invention to 
provide a multilayer through type capacitor, in which crosstalk due to 
capacitive coupling between the multilayer through type capacitor elements 
is reduced despite a simple terminal electrode configuration. 
For this purpose, a shielding electrode is provided in the present 
invention between multilayer through type capacitor elements, which 
constitute the multilayer through type capacitor array, and the external 
conductor of the multilayer through type capacitor is connected to this 
shielding electrode. 
By such an arrangement, electrostatic shielding can be achieved between the 
multilayer through type capacitor elements, which constitute the 
multilayer through type capacitor array, despite a simple terminal 
electrode configuration. As a result, capacitive coupling is decreased, 
and crosstalk between signals passing through the adjacent multilayer 
through type capacitors is reduced.

DETAILED DESCRIPTION OF THE INVENTION 
FIGS. 3a through 3k represent an embodiment of a multilayer through type 
capacitor array of the present invention, which comprises a four-layer 
dielectrics combining four multilayer through type capacitors as in the 
conventional multilayer through type capacitor array of FIGS. 1a to 1k. 
This multilayer through type capacitor array comprises a first dielectric 
sheet 31, a second dielectric sheet 32, a third dielectric sheet 33 and a 
fourth dielectric sheet 34, each designed in rectangular form and layered 
in that order. 
FIGS. 3b, 3d, 3f and 3h each represents a cross-sectional view of a 
dielectric sheet of 3a, 3c, 3e and 3g respectively along the lines b--b, 
d--d, f--f and h--h. 
As shown in FIG. 3g, on the first dielectric sheet 31, an internal 
electrode 35 made of conductive material, extended in longitudinal 
direction of the rectangle and reaching the two shorter sides of the 
rectangle, is provided. At positions equally dividing this internal 
electrode 35, three through-holes 38 penetrating the first dielectric 
sheet 31 are formed. 
As shown in FIG. 3h, conductive materials 42 are filled in through-holes 
38, and a conductive layer 45 is provided on each of the conductive 
materials 42 exposed to surface of the first dielectric sheet 31 where the 
internal electrode 35 is not present. Conductive layer 45 is not 
necessarily required. 
As shown in FIG. 3e, on the second dielectric sheet 32, four internal 
electrodes 36 made of conductive material, extended in lateral direction 
of the rectangle and reaching the two longer sides of the rectangle, are 
provided. Between these internal electrodes 36 and at positions 
corresponding to where three through-holes 38 penetrating the first 
dielectric sheet 31 are formed, three through-holes 39 penetrating the 
second dielectric sheet 32 are formed. As shown in FIG. 3f, these 
through-holes 39 are filled with conductive materials 43. 
As shown in FIG. 3c, on the third dielectric sheet 33, an internal 
electrode 37 made of conductive material, extended in longitudinal 
direction of the rectangle and reaching the two shorter sides (similar to 
the internal electrode 35 on the first dielectric sheet 31), is provided. 
At the position equally dividing this internal electrode 37, three 
through-holes 40 penetrating the third dielectric sheet 33 are formed. On 
upper surface of the placed dielectric sheet 33, the dielectric sheet 34 
shown in FIGS. 3a and 3b having no internal electrode is placed. 
External configuration of the multilayer through type capacitor array with 
the above arrangement, turned upside down and seen from below, is shown in 
FIG. 3i and a cross-sectional view along the line j--j is shown in FIG. 
3j. 
On the internal electrodes 36, four terminal electrodes 41 are formed, 
which are partially extended on mounting surfaces, i.e. upper and lower 
surfaces, by means such as printing in order to connect each of the 
multilayer through type capacitor, constituting the multilayer through 
type capacitor array, to external printed circuit pattern. These terminal 
electrodes 41 are partially extended on mounting surfaces, i.e. upper and 
lower surfaces, but the extended portions are not necessarily required. 
The internal electrodes 35 and 37 are electrically connected to the 
conductive materials 46 integrating the conductive materials 42, 43 and 44 
filled in the through-holes 38, 39 and 40 and are further electrically 
connected to the conductive layers 45 formed on the conductive materials 
46. 
The conductive materials 46 thus formed are arranged between the multilayer 
through type capacitors, which constitute the multilayer through type 
capacitor array. Therefore, by grounding the conductive layer 45 connected 
to the conductive materials, electrostatic shielding between the 
multilayer through type capacitors can be achieved, and this prevents 
crosstalk, which causes problems in the conventional type multilayer 
through type capacitor array. 
Electrical connection diagram of this multilayer through type capacitor 
array is shown in FIG. 3k. 
In this multilayer through type capacitor array, unlike conventional 
multilayer through type capacitor of FIGS. 1a to 1k, the internal 
electrodes 35 and 37, constituting external conductors of four multilayer 
through type capacitors, are grounded via the conductive material 46. As a 
result, there is no influence from common impedance due to external 
conductors in these multilayer through type capacitor arrays. Thus, no 
crosstalk occurs. 
In this multilayer through type capacitor array, unlike the conventional 
multilayer through type capacitor of FIGS. 1a to 1k, the distance from the 
external conductor of the multilayer through type capacitor arranged 
inside to the grounding terminal is equal to the distance from the 
external conductor of the multilayer through type capacitor arranged 
outside to the grounding terminal. As a result, electrical characteristics 
of the multilayer through type capacitors are uniform. 
Further, in this multilayer through type capacitor array, unlike the 
conventional multilayer through type capacitor of FIGS. 2a to 2k, the 
terminal electrode to connect the external conductor is arranged at a 
different position from that of the terminal electrode to connect the 
internal conductor. This makes it possible to miniaturize multilayer 
through type capacitor array and reduce difficulties when mounting. 
FIGS. 4a to 9b show further modified embodiments of the invention. 
In these figures, external configurations of multilayer through type 
capacitor array of the embodiments are shown in "a"s, and cross-sectional 
views along the line b--b are given in "b"s. To simplify explanation, 
descriptions and symbols are not given for the same portion as in the 
embodiment of FIGS. 3a to 3k. 
To simplify explanation, in the multilayer through type capacitor array of 
FIGS. 4a and 4b, external configuration and cross-section, turned upside 
down and seen from below, are shown similarly to the multilayer through 
type capacitor array of the embodiment of FIGS. 3i and 3j. 
In the multilayer through type capacitor array of this embodiment, 
conductors 46 of the multilayer through type capacitor array of FIG. 4a 
are connected by the terminal electrode 47, and this ensures reliable 
soldering when mounting. 
In a multilayer through type capacitor array of the embodiment shown in 
FIGS. 5a and 5b, instead of the fourth dielectric sheet 34 of the 
multilayer through type capacitor array of FIGS. 4a and 4b, a fourth 
dielectric sheet 48 having through-holes is placed. Conductive materials 
49 are provided by filling conductive materials inside these 
through-holes. This makes it possible to provide a more reliable shielding 
effect. 
In a multilayer through type capacitor array of the embodiment of FIGS. 6a 
and 6b, in addition to the terminal electrode 47 of the multilayer through 
type capacitor array of FIG. 5a and 5b, another terminal electrode 50 is 
provided on the opposite side. This makes it possible to provide a more 
reliable shielding effect by another terminal electrode 50. 
In a multilayer through type capacitor array of the embodiment of FIGS. 7a 
and 7b, instead of the fourth dielectric sheet 34 of the multilayer 
through type capacitor array of FIGS. 3a to 3k, a fourth dielectric sheet 
48 having through-holes is placed. Conductive materials 49 are provided by 
filling conductive materials inside these holes. 
In the multilayer through type capacitor array with the above arrangement, 
there is no need to care about front side or rear side of the multilayer 
through type capacitor array when mounting. 
In a multilayer through type capacitor array of the embodiment of FIGS. 8a 
and 8b, a terminal electrode similar to the terminal electrode 9 of the 
conventional multilayer through type capacitor array of FIGS. 1i and 1j is 
provided on the multilayer through type capacitor array having conductive 
material 46 shown in FIGS. 4a and 4b, and a terminal electrode 51 is 
provided by integrating this terminal electrode with terminal electrode 47 
of the multilayer through type capacitor array of the embodiment shown in 
FIG. 4. 
In the multilayer through type capacitor array with the above arrangement, 
this terminal electrode 51 can ensure further shielding effect, and there 
is no need to care about front side or rear side of the multilayer through 
type capacitor array when mounting. 
In a multilayer through type capacitor array of the embodiment shown in 
FIGS. 9a and 9b, a terminal electrode similar to the terminal electrode 9 
of the conventional multilayer through type capacitor array of FIGS. 1i 
and 1j is provided on the multilayer through type capacitor array having 
the conductor 49 in FIGS. 5a and 5b so that a terminal electrode is 
provided by integrating this terminal electrode with terminal electrode 47 
of the multilayer through type capacitor array of the embodiment shown in 
FIGS. 5a and 5b. 
In the multilayer through type capacitor array with the above arrangement, 
this terminal electrode 51 can ensure further shielding effect, and there 
is no need to care about front side or rear side of the multilayer through 
type capacitor array when mounting. 
In the embodiments shown in FIGS. 3a to 7b among the embodiments explained 
in connection with FIGS. 3a to 9b, the internal conductors of the 
multilayer through type capacitors provided inside are completely enclosed 
by the external conductors and conductive materials, while the internal 
conductors of the multilayer through type capacitors provided outside are 
not completely enclosed. 
On the contrary, in the embodiments shown in FIGS. 8a, 8b and 9a, 9b, the 
internal conductors of the multilayer through type capacitors provided 
outside are completely enclosed by the external conductors, conductive 
materials and connection electrodes. 
By the above arrangement, it is possible to produce a multilayer through 
type capacitor array which provides uniform electrical characteristics for 
each of the multilayer through type capacitors. 
FIGS. 10a to 12b each represents a configuration example of an array of 
multilayer through type capacitors, in which internal conductors of the 
multilayer through type capacitor provided outside are completely enclosed 
by external conductors, conductive materials and connection electrodes. 
In these figures, "a"s represent external configuration of the multilayer 
through type capacitor array of the embodiments, and "b"s represent a 
cross-sectional view along the line b--b. To simplify explanation, 
descriptions and symbols are not given for the same portion as in the 
embodiment of FIG. 3a to 3k. 
In a multilayer through type capacitor array of a configuration example 
shown in FIGS. 10a and 10b, a terminal electrode 52 similar to the 
terminal electrode 9 of the conventional multilayer through type capacitor 
of FIGS. 1i and 1j is provided on the multilayer through type capacitor 
array shown in FIGS. 7a and 7b. 
In a multilayer through type capacitor array of a configuration example of 
FIGS. 11a and 11b, the conductive material 49 in the multilayer through 
type capacitor array shown in FIGS. 10a and 10b is designed as a small 
conductive material 53, and conductive material 52, which connects the 
first internal electrode 35 and the second internal electrode 37, is 
provided outside. 
In a multilayer through type capacitor array of a configuration example 
shown in FIG. 12a and 12b, two layers of dielectric sheets 54 and 55 are 
laid on the multilayer through type capacitor array shown in FIGS. 7a and 
7b. 
In the embodiments described above, the dielectric sheet is designed in 
rectangular form, however the dielectric sheet may be designed in any form 
according to the present invention can be achieved. 
The plurality of internal electrodes contacts may be placed at any position 
according to the present invention. A single internal electrode contact 
may be placed at any position according to the present invention. 
As is evident from the above explanation, it is possible by electrostatic 
shielding of conductive material filled in the through-holes to provide a 
decrease of crosstalk and uniform electrical characteristics for each 
multilayer through type capacitor, to miniaturize the multilayer through 
type capacitor array, and to reduce difficulties when mounting.