High capacitance laminated buss and method of manufacture

A laminated buss bar comprised of a pair of elongated flat conductors separated by an incorporated dielectric/electrode structure, the dielectric/electrode structure being sandwiched between the flat conductors on the opposite sides thereof, and a method of manufacture thereof. The buss bar is formed by depositing a flat layer of dielectric material on the inwardly facing surface of a first flat conductor and then forming an electrode of conductive material on the deposited layer of dielectric material. The inwardly facing surface of the first flat conductor also serves as one electrode of a capacitor. Subsequently, the formed conductive material electrode electrically and mechanically contacts the inwardly facing surface of a second flat conductor. Accordingly, the formed conductive material electrode, dielectric material, and one of the pair of elongated flat conductors form a capacitor.

BACKGROUND OF THE INVENTION 
This invention relates to multilayer or laminated buss bars which include 
incorporated capacitors or condensers. More particularly, this invention 
relates to an improved high capacitance laminated buss bar with 
incorporated capacitors wherein the buss bar has superior temperature and 
frequency properties and is inexpensive to manufacture as compared to buss 
bars of the prior art. 
With the trend towards large scale piling of integrated circuits in 
addition to the high density packaging of electronic parts on circuit 
boards, the power supply buss bars and signal supply buss bars are 
required to have low inductance and low characteristic impedance and high 
distributive capacitance in order to avoid the undesirable effects of high 
frequency noise. 
Laminated buss bars in which conductor layers are interleaved and spaced 
with an insulating film of relatively high dielectric constant are known 
for use as power supply and signal supply components, these components 
commonly being referred to as multilayer or laminated buss bars. However, 
the dielectric materials normally used as the interleaved insulating 
spacer have limits as to dielectric constant and or distributed 
capacitance. The use of materials of very high dielectric constant has 
been proposed, but such materials have limitations, primarily as to cost. 
In U.S. Pat. No. 4,266,091, all of the contents of which are incorporated 
herein by reference, a laminated buss bar is disclosed with incorporated 
capacitors which result in a significantly improved power or signal 
distribution system. U.S. Pat. No. 4,266,091 involves the direct 
incorporation in the buss bar of capacitors which preferably consist of 
relatively thick ceramic chips, i.e., between about 0.1 to 0.3 
millimeters. These relatively thick chips must also have a high dielectric 
constant. While buss bars constructed in accordance with U.S. Pat. No. 
4,266,091 offer significant advantages, limitations exist in that 
temperature characteristics and frequency characteristics can only be 
improved by the use of expensive chips. Thus, for reasons of economy, 
inexpensive chips have had to be generally employed, at a sacrifice of 
properties such as temperature and frequency. Yet another problem of the 
buss bars of U.S. Pat. No. 4,266,091 is that the capacitor chips are 
usually fixed to the conductors by a suitable adhesive. As a result of 
this need for the application of adhesive, the number of process steps 
increases and hence the cost of manufacture increases. 
SUMMARY OF THE INVENTION 
The above discussed and other problems of the prior art are overcome or 
alleviated by the bus bar of the present invention. In accordance with the 
present invention, a dielectric layer comprised of a highly dielectric 
material is provided directly on one surface of a buss conductor. This one 
surface also serves as one electrode of a capacitor in the structure of 
the present invention. An electrode is then formed on the dielectric 
layer; and a second buss conductor is placed over the dielectric/electrode 
structure, whereby the dielectric/electrode structure is sandwiched 
between buss conductors on the opposite sides thereof. The novel structure 
of the buss bar of the present invention provides a high capacitance 
laminated buss having superior temperature and frequency properties. This 
novel high capacitance laminated buss bar is also extremely inexpensive to 
produce relative to prior art buss bars such as that buss bar described in 
U.S. Pat. No. 4,266,091.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIGS. 1 and 2, a buss bar in accordance with a first 
embodiment of the present invention is shown. The buss bar of the present 
invention generally comprises two conductors 8 and 9 made of any suitable 
conductive material such as, for example, copper. Inner surface 8A of 
lower conductor 8 is provided with a dielectric layer 10 consisting of a 
highly dielectric material such as, for example, a ceramic or the like. 
Dielectric layer 10 is formed directly on and bonded to conductor surface 
8A by any suitable means including sputtering, vapor deposition, melt 
injection or the like. The thickness of dielectric layer 10 should be 
between several micrometers and 0.2 millimeters. An electrode 11 comprised 
primarily of nickel or any other similarly good conductive material is 
then formed on surface 10A of the dielectric layer 10, also by use of 
sputtering, vapor deposition or the like. A second buss conductor 9 is 
then placed in position with surface 11A of electrode 11 in mechanical and 
electrical contact with surface 9A of conductor 9. Note that conductors 8 
and 9 are in a facing spatial relationship. Thus, a resulting structure is 
obtained wherein a condenser or capacitor, consisting of electrode 11, 
dielectric 10 and surface 8A, is formed directly between conductors 8 and 
9. It will be appreciated that nickel or tin plating or other suitable 
protective means may be provided on the surface of conductors 8 and 9 as 
an aid in preventing corrosion. 
The laminated buss bar of the present invention having the above discussed 
structure essentially consists of a highly dielectric material such as a 
ceramic being deposited on conductor 8 as dielectric layer 10 with a 
conductive material being deposited on dielectric layer 10 as an electrode 
11 by sputtering or a similar method. It should be understood that the 
thicknesses of the dielectric layer 10 and electrode 11 may be made 
extremely small so that a selected value of dielectric constant may be 
obtained. Accordingly, the dielectric layer 10, electrode 11 and surface 
8A constitute an internally provided capacitor. Buss conductor 9 may be 
bonded to electrode 11 by any suitable adhesive; and/or the assembly may 
be incapsulated in an outer layer of insulation. Consequently, important 
properties of a condenser or capacitor such as temperature and frequency 
will be improved relative to prior art buss bars by selection and control 
of the capacitor materials. Moreover, the material costs involved in 
producing the above-mentioned buss bar are reduced. 
Referring now to FIG. 3, another embodiment of the buss bar of the present 
invention is shown. In FIG. 3, the buss bar includes a plurality of 
capacitors or condensers formed in accordance with the method described 
above. Thus, dielectric layers 14 and 15 and electrodes 16 and 17 are 
provided as alternating laminated layers on surface 12A of conductor 12 
and between the other conductor 13 in a similar fashion as in FIGS. 1 and 
2. Note that uppermost electrode 17 mechanically and electrically contacts 
upper conductor 13. 
The multiple capacitors provided in the buss bar of FIG. 3 may be easily 
interconnected in either a series or a parallel circuit. For example, 
during the lamination process of dielectric layers 14 and 15 and 
electrodes 16 and 17, the layers may be alternated as shown such that the 
electrodes are connected in series between the conductors 12 and 13. 
However, if electrode 16 formed between dielectric layers 14 and 15 is 
connected to either conductor 12 or 13 in a suitable manner, the resulting 
connection provided between conductors 12 and 13 will be in parallel. 
Thus, a laminated buss bar in accordance with the present invention having 
improved temperature and frequency properties and low costs may be 
provided in either a series or parallel connection depending upon the 
particular application needed. 
Referring now to FIG. 4, yet another embodiment of the laminated buss bar 
of the present invention is shown. In this embodiment, a dielectric layer 
18 is formed both on planar surface 19A of conductor 19 and on side 
surface 19B of the conductor 19 in accordance with the method described 
above. Subsequently, electrode 20 is formed on the dielectric layer 18 and 
is electrically and mechanically connected to the oppositely disposed 
conductor 21. This embodiment may be particularly advantageous in the 
event that conductors 19 and 21 should slide relative to one another 
during the lamination procedure. Thus, with the embodiment of FIG. 4, 
undesirable contact (resulting from relative sliding) between conductors 
19 and 21 is prevented by dielectric layer 18. Dielectric layer 18 also 
prevents changes in the temperature and frequency properties of the buss 
bar which may occur as a result of the shifting of positions of the 
conductors even if that shifting does not result in contact of the 
conductors. 
FIG. 5 shows yet another embodiment of the buss bar of the present 
invention. In FIG. 5, notches 22A and 23A are provided in selected 
locations along the two conductors 22 and 23. The notches 22A,23A are 
oppositely disposed on each respective conductor such that the notches 
face each other in a center of symmetrical fashion. Condensers or 
capacitors consisting of dielectric layers 24, electrodes 25 and one of 
the pair of elongated flat conductors which are similar to those described 
above are provided between adjacent notches 22A on conductor 22; and the 
buss conductors 22 and 23 are then laminated together. As a result of this 
arrangement, it is possible to cut or to sever the laminated buss at 
notches 22A and 23A after conductors 22 and 23 have been superimposed on 
each other without affecting the features of the present invention 
including the improved temperature and frequency properties. The 
embodiment of FIG. 5 therefore, provides a method of continuously 
manufacturing the improved buss bar at a low cost. 
In accordance with the laminated buss of the present invention, a 
dielectric layer and an electrode are provided directly on the surface of 
a first conductor (which also acts as a capacitor electrode) and are 
sandwiched by an oppositely disposed second conductor. Thus, the electrode 
electrically and mechanically contacts the second conductor whereby a 
structure is obtained having a dielectric electrode structure which is 
incorporated directly between two conductors as part of a unified one 
piece construction. Consequently, for a given value of required 
capacitance, a thin dielectric layer will provide a buss bar having 
satisfactory properties. Moreover, since the adhesion step, which is a 
necessary step in prior art methods for incorporating capacitor chips, 
becomes unnecessary, various properties such as temperature and frequency 
can be improved and manufacturing cost reductions can be realized. 
While preferred embodiments have been shown and described, various 
modifications and substitutions may be made thereto without departing from 
the spirit and scope of the invention. Accordingly, it is to be understood 
that the present invention has been described by way of illustrations and 
not limitation.