Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a solid electrolyte chip capacitor
desi~ned for application to printed circuit boards, and especially to an
improved chip for facilitating automatic assembling of printed circuit
structures.
Many kinds of such capacitors have been proposed for application to
printed circuit boards. Such capacitors have their anode and cathode terminals
on the bobtom surface so as to enable direct contact with corresponding con-
ductors on a printed circuit board. Examples of this type of capacitor are
disclosed in United States patent Nos. 3,855,505 and 4,247,883. ~ecently, an
automa~ic process has been developed for assembling printed circuit structures
and the so-called "vacuum chuck" technique has come to be used conveniently
~or ~rar~sferring capacitors to specified locatlons on the board. The "vacuum
chuck" :Ls a device for attracting an object to a suction port thereof, which
is connected to a reduced pressure or "vacuum" source, to ~ransfer it to
anywhere desired. For successfully effecting a "vacuum chucking" operation,
the at~racted surface of the capacitor, which is generally the top sur~ace
thereof, must be flat and smooth. However, the prior art capacitors are
- unsuitable for this purpose since they have been manufacture~ without taking
this matter into account. Though the capacitor o the above-mentioned patent
~0 No. 4,247,883 is shown as having a "flat and smooth" top surface, the resin-
filled surface really has small undulations whichmayresult in insufficient
chucking. Though a smooth surface can be obtained by resin-molding the capa-
citor with a metal mold, the cost of manufacture rises. Another United States
patent No. 3,550,228 discloses a chip capacitor having a cap whose top surface
is flat and smooth. Though this capacitor seems suitable for use with" vacuum
chuck", it is complicated in structure and quite expensive.
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Therefore, an object of this invention is to provide an improved
solid electrolyte chip capacitor having a flat and smooth top surface for
perfect vacuum chucking~ and a simple structure for avoiding unwanted increase
of manufacturing cost.
According to this invention, there is provided a capacitor including
a capacitor element and a pair of metal terminal members having L-shaped
cross-section. The terminal members are bonded to the anode and cathode layers
of the capacitor element, respectively, and arranged facing each other and
disposing the horizontal portions of the "L" in a common plane under the
capacitor element. The space between the terminal members is filled with in-
sulating material surrounding the capacitor element, and a heat-resistant
synthetic resin plate is affixed to the top surface of the filled insulating
material.
Now, the invention will be described in more detail with reference to
the accompanying drawings, in which:
Figure 1 is a perspective view of an embodiment of the capacitor
according ~o this invention;
Figure 2 is a sectional side view of the embodiment of Figure l; and
Figure 3 is a sectional side view of another embodiment of a capa-
citor according to this invention.
Throughout the drawings, like reference numerals are given to corres-
ponding structural components.
Referring to Figures 1 and 2, the capacitor includes a pair of
channel type metal terminal members 1 and 2 having L-shaped cross-section.
The terminal members 1 and 2 are arranged, as shown, to have their vertical
portions facing each other and their horizontal portions in a common plane.
An anode conductor ~ of a capacitor element 3 is welded to the terminal member
1 and a cathode layer 5 of the element 3 is bonded to the terminal member 2
with solder or electrically conducting adhesive 6. The capacitor element 3 is
embedded in insulating synthetic resin 8 filling a space between the two ter-
minal members 1 and 2, and a thin synthetic resin plate 7 is adhered to the top
surface of the resin 8.
The terminal members 1 and 2 may be m~de from a solderable metal
plate~ such as of copper, nickel or nickel silver, or a suitable metal plate
plated with solderable metal, such as solder, tin or gold. The capacitor ele-
ment 3 may be prepared in conventional manner. For example, suitable powdered
valve metal, preferably tantalum, is press-formed and sintered to form an
anode body, and an oxide layer, a semiconductor layer and a cathode layer are
5c~luontially deposlted in this order on the anode body. The "valve metal" îs
suc.h a metal as tantalum, alumint3m~ ~irconium, titanium, niobium or like,
which exhibits "valve action", that is, unidirectional electric conductivity
between the metal and its oxide coating. The resin 8 may be selected from
suitable electrically insulating air-hardening, radiation hardening, or
thermo-hardening adhesive resins, such as epoxy resin. The resin plate 7
may be made preferably of polyimid resin, polyethylene fluoride resin or glass-
:~illed epoxy resin. The resin plate 7 is preferably adhered to the resin
surface by adhesive force of the resin 8 itsel~ before it cures, though it may
be adhered with a separate adhesive agent after curing of the resin 8. The
thickness of the plate 7 can be small enough, such as 0.2 millimeter, for
example, so long as any possible undulation of the sur~ace of the resin 8 does
not appear on the surface of the plate 7.
Tn Figure 3~ the resin plate 7 covers only a part of the surface of
the resin 8. The shape of the plate 7 may be not only rectangular, but also
circular or other any suitable shape.
The capacitors of this invention can be manufactured efficiently,
in similar manner as shown in the aforementioned United States patent No.
4,247,883, by arranging a pair of long electrode channels having L-shaped
cross-section in parallel, connecting a plurality of capacitor elements to the
two channels to form a ladder-like structure, pouring hardening resin between
the channels to embed the capacitor elements therein, putting a thin
plastic strip on the top surface of the resin to adhere it thereto and, after
curing of the resin, separa~ing the discrete capacitors by sawing.
As describod above, the capacitor of this invention has a simple
structure and can be manufactured readily at low cost, while keeping its top
surEace highly ~Elat and smooth.
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