United States Patent [191
`Insetta et a1.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,953,273
`Sep. 4, 1990
`
`[54] PROCESS FOR APPLYING CONDUCI'IV'E
`TERMINATIONS T0 CERAMIC
`COMPONENTS
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`4,241,378 12/1980 Dorian ......................... .. 29/2542 X
`
`-
`
`4,353,153 10/1982 Prakash . . . . . . . . . . .
`
`. . . . .. 29/25.42
`
`v.
`Inventors: victor D‘
`Monsorno, both of Jacksonville, Fla;
`John F. Do _
`Simpsonvme, S'C.
`
`Ct al. N.
`
`.
`
`X
`
`FOREIGN PATENT DOCUMENTS
`137565 4/1985 European Pat. Off. .
`
`.
`.
`.
`.
`[73] Assxgnee: American Technical Ceramics
`Corporation’ Huntington Station,
`N.Y.
`
`_
`[21] Appl' No" 356’518
`
`' Primary Examiner—Carl E. Hall
`. __
`Attorney, Agent, or Firm Edward H. Loveman
`[57]
`ABSTRACT
`In this process a conductive ?rst layer composed of
`?nely divided metal and ?nely divided ceramic material
`in an organic carrier is applied to a surface of an unsin
`tered ceramic body. The conductive layer forms termi
`nations when the body, and the conductive layer are
`co?red to sinter and form a unitary, integral, monolithic
`structure. A second conductive metal layer may be
`applied to the ?rst layer prior to co?ring to improve
`[51] Int. Cl.5 ............................................. .. H01G 4/ 12
`attachment capabilities of the component. Leads may be
`[52] U.S. Cl. ................................... .. 29/2542; 29/854;
`264/61; 361/309; 361/321 C attached to the conductive terminations if desired.
`[58] Field of Search ..................... .. 29/2542, 854-856;
`361/308, 309, 321 C, 321 CC; 284/61, 62
`
`[22] Filed:
`
`Ma‘), 25’ 1989
`
`18 Claims, 1 Drawing Sheet
`
`000001
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`AVX CORPORATION 1008
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`

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`US. Patent
`
`Sep. 4, 1990
`
`4,953,273‘
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`000002
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`1
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`PROCESS FOR APPLYING CONDUCI‘IVE
`TERNIINATIONS TO CERAMIC COMPONENTS
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`5
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`10
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`4,953,273
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`of the joint, both mechanically and electrically. Addi
`tionally, capacitor performance may be degraded by
`trapped plating solutions or other foreign contaminants
`introduced during the plating process. The net result is
`that the capacitors are compromised and integrity of the
`device is lost. In the prior U.S. Pat. No. 3,235,939
`abovementioned, it was proposed to apply the ?nely
`divided metallic terminations to the green, ceramic
`capacitors as an economy measure prior to sintering the
`ceramic. However, again poor adherence of the metal
`terminations to the capacitor bodies was experienced,
`and unacceptable changes in expected capacitor param
`eters resulted. In another prior art process, disclosed in
`U.S. Pat. No. 4,246,625 entitled “Ceramic Capacitors
`with Co-?red End Terminations”, the end terminations
`are composed of ?nely divided particles of either nickel
`or copper together with glass frit and mangenese diox»
`ide, in which end terminals are co-?red with the capaci
`tor body. Termination ends of this type, which contain
`glass frit, suffer from the same de?ciency as mentioned
`hereinabove, i.e. diminished solderability of connec
`tions etc.
`
`25
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`This invention relates to the art of manufacturing
`ceramic components and more particularly concerns an
`improved process for applying conductive paths or
`conductive terminations to ceramic components such as
`capacitors.
`'
`2. Description of the Prior Art
`In prior U.S. Pat. No. 3,235,939 issued Feb. 22, 1966
`and reissued as U.S. Pat. No. Re.26,42l on July 2, 1966,
`there is described processes for manufacturing a minia
`ture ceramic capacitor some of which are currently
`used in the art.
`One such process utilizes a ?nely divided metallic
`electrode which is applied to a strip or sheet of unsin
`20
`tered ceramic. Then a multiplicity of these coated and
`uncoated sheets are assembled one above the other in
`the correct sequence and orientation. The assembly is
`cut into individual pieces, the pieces compressed under
`a pressure and then ?red to sinter the ceramic. After the
`?ring, a termination material composed of ?nely di
`vided metal in an organic carrier, is applied to the ex
`posed electrode ends of the ceramic capacitors, thereby
`forming the terminations. The capacitors are then
`brought to a suf?cient temperature to fuse the termina
`30
`tions to the body of the capacitor. Terminal leads may
`then be attached (soldered, brazed, welded, etc.) to the
`conductive terminations.
`In the above described prior art process, a number of
`dif?culties result from the method of forming the termi~
`nations. One of the principal dif?culties is that there
`may be poor adhesion of the terminations to the ceramic
`body of the capacitor, so that contact is often tenuous
`between some electrodes of the capacitor and the ?red
`terminations, whereby the electrical parameters of the
`capacitor may vary in an unpredictable and erratic
`manner.
`Another principal dif?culty of this prior art process is
`that since the second ?ring must be at a lower tempera
`ture than the ?rst ?ring, the maximum operating tem
`perature of the capacitor is decreased to the lower tem
`perature of the second ?ring. In another prior art pro
`cess, currently in use, the termination material is coated
`after the ?rst ?ring, and is comprised of a ?nely divided
`metal and ?nely divided glass particles (frit) in an or
`ganic liquid or paste. Although the glass frit improves
`adhesion, it frequently diminishes solderability of elec
`tric connections, and due to the glass content, is brittle
`and therefore,easily broken and exhibits poor thermal
`shock. In addition, the metals commonly used in the
`terminations tend to dissolve (leach) into the solder used
`in the terminal lead attachment. If the second ?ring
`used to fuse the glass frit is performed at a temperature
`equal to or higher than that of the ?rst ?ring, then the
`termination layer is is likely to separate from the ce
`ramic capacitor.
`In order to improve the performance of the termina
`tions made with glass frit, a metal plating process is
`sometimes used to complete and enhance the termina
`tion layer of a ceramic component. This plating process
`may introduce further dif?culties in that strong solu
`tions are used, which etch the glass frit and ceramic,
`causing nonuniform interfaces between the terminations
`and the ceramic bodies, again leading to a degradation
`
`35
`
`SUMMARY OF THE INVENTION
`It is therefore a principal object of the present inven
`tion to provide a method or process of forming a reli
`able conductive termination or conductive paths for
`ceramic electronic components such as capacitors, re
`sistors, hybrids, etc, which avoids the difficulties and
`disadvantages heretofore experienced with prior art
`methods of applying terminations. According to the
`invention, after individual ceramic components such as
`a capacitor are fabricated in an unsintered state, a termi
`nation layer composed of a mixture of ?nely divided
`metal and ceramic of the same or similar composition as
`I that of the ceramic capacitor,in a liquid or paste organic
`carrier, is applied to the exposed electrode sides of the
`capacitor pieces. Then the capacitors are sintered at
`their normal ?ring temperature. During the sintering
`process, the ceramic in the termination layer is simulta
`neously sintered to the capacitor body by solid state
`reactions and forms an integral mechanical bond, which
`results in a monolithic co-?red termination. Excellent
`electrical conductivity between every electrode of the
`capacitor and the sintered termination is achieved with
`the metal composition in the termination layer. The
`termination layer requires the proper ceramic to metal
`composition in order to achieve optimum characteris
`tics. If the composition of the termination layer is the
`same as the ceramic in the body, the ceramic in the
`termination layer is typically from 10% to 60% ceramic
`by volume in the ceramic-metal composition. If less
`electric conductivity is permissible of the ceramic com
`ponent, then the percentage of ceramic may be in
`creased to as much as 75% by volume. If the type of
`ceramic in the termination layer differs from the ce
`ramic body through the use of ?ux compounds, such as
`high temperature glasses or clays, for example, steatite,
`then the composition of ceramic by volume of the ter
`mination layer may be reduced to as low as 2%.
`When the higher percentages of ceramic are used, to
`enhance physical performance, solderability of the ter
`mination layers is reduced. To compensate for this con
`dition, additional layer of ?nely divided metal with a
`lesser percentage of ceramic or without ceramic is ap
`plied over the initial ceramicmetal termination layer,
`prior to any sintering process. The capacitor and termi
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`or to customize the capacitor terminations. The layers
`nation layers are then sintered, as de?ned, into a mono
`lithic integral unit. This co?ring technique solves the
`25, 25' are composed of ?nely divided metal, with or
`prior art problems of poor adherence, poor solderabil
`without ceramic, in an organic liquid or paste form.
`ity, unstability of electrical performance, and other
`After co?ring, the layers 22, 24, 25, and 25’ will be
`dif?culties heretofore encountered.
`integrated with each other and with the sides of the
`These and other objects and many of the attendant
`ceramic 30 block or body 12' and with the electrodes
`advantages of this invention will be readily appreciated
`14, 16. Thereafter, solder 26 and leads 28 may be applied
`as the same becomes better understood by reference to
`to the capacitor terminations 22’, 24’ to complete the
`the following detailed description when considered in
`assembly of the capacitor 10" as shown in FIGS. 7 and
`connection with the accompanying drawings in which:
`8.
`If it is desired to improve the cutting of the assembly
`BRIEF DESCRIPTION OF THE DRAWINGS
`of unsintered ceramic layers, after compressing the
`' FIG. 1 is a greatly enlarged perspective view of an
`layers as referred to above and in the abovementioned
`un?red ceramic capacitor unit with spaced electrodes
`U.S. Pat. No. 3,235,939, the assembly may be heat
`having exposed edges, at one stage of manufacture of
`treated to coalesce the particles and remove the binder,
`the capacitor;
`which more easily permits the assembly to be put into
`FIG. 2 is a further enlarged cross sectional perspec
`blocks 12 by saws or knives. Insofar as the present in
`tive view taken along line 2-2 of FIG. 1;
`vention is concerned, the ceramic body of the block 12
`FIG. 3 and FIG. 4 are horizontal sectional views
`whether un?red or partially ?red to remove the binder,
`taken along lines 3-3 and 4-4 repectively of FIG. 1;
`the body will still be unsintered so that the layers 22, 24,
`FIG. 5 is a perspective view of the ceramic capacitor
`25 and 25' will integrate with the block or body 12 and
`unit of FIG. 1 with termination layers applied prior to
`the electrodes 14, 16 after they are co?red.
`co?ring;
`Although the invention has been explained in connec
`FIG. 6 is a view similar to FIG. 5 showing the unit of
`tion with a multiple layered capacitor it is possible to
`FIG. 5 with additional termination layers applied prior
`25
`apply the same process to a capacitor having a single,
`to co?ring;
`unsintered ceramic body, such as the capacitor illus
`FIG. 7; is a side view of the capacitor unit of FIGS.
`trated in US. Pat. No. 4,205,364. The termination layers
`5 or 6 after ?ring and application of terminal leads; and
`composed of a mixture of ceramic material and a ?nely
`FIG. 8 is an end view of the completed capacitor unit
`divided metal for the primary layer, and if required and
`taken along line 8-8 of FIG. 7.
`?nely divided metal, with or without the ceramic com
`position in the second layer, will be applied, and co?red
`with the ceramic body 12 and its electrode as explained
`above with regard to FIGS. 5 and 6. Then the capaci
`tors may also receive the addition of the solder joints
`and/or leads as explained in connection with FIGS. 7
`and 8.
`It is preferable that the composition of the termina
`tion layer or conductive path be the same as the ceramic
`composition of the body 12, and in this event the ce
`ramic in the termination layer is typically 10% to 60%
`ceramic by volume. If the component is a resistor or
`other resistive component or if less electric conductiv
`ity is permissible of the ceramic component, then the
`percentage of ceramic to metal in the termination layer
`or conductive path may be increased to as much as 75%
`by volume. Additionally, if the ceramic in the termina
`tion layer or conductive path differs from that of the
`ceramicin the body through the use of a flux agent, then
`the percentage of ceramic to metal in the termination
`layer may be reduced to as low as 2% by volume.
`It should be understood that although the invention
`has been illustrated and explained in connection with
`capacitors, the process is equally applicable to other
`ceramic electronic components such as resistors, induc
`tors, networks, hybrids, etc. The aforementioned pro
`cess when used in hybrids may be applied to form con
`ductive paths so that the completed hybrid looks very
`much like a printed circuit board to which electronic
`components may be subsequently applied.
`It should also be understood that the foregoing re
`lates to only a preferred embodiment of the invention
`which has been by way of example only, and that it is
`intended to cover all changes and modi?cations of the
`examples of the invention herein chosen for the purpose
`of the disclosure, which do not constitute departures
`from the spirit and scope of the invention.
`What is claimed is:
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Referring now to the drawings wherein like refer
`ence characters designate like or corresponding parts
`throughout, there is illustrated in FIGS. 1-4, a capacitor
`generally designated as reference numeral 10 at one
`stage of manufacture. The capacitor 10 has a ceramic
`body or block 12 composed of unsintered ceramic mate
`rial. In the rectangular body 12 are spaced metallic
`40
`layers 14, 16 alternately terminating at opposite ends on
`sides 18, 20 of the body 12. The body 12 is produced by
`vertically assembling a plurality of sheets into an assem
`bly, compressing the assembly, as explained in detail in
`the abovementioned US. Pat. No. 3,235,939, and cut
`ting the assembly into the individual parts or bodies 12.
`Now according to the invention, the sides 18 and 20
`of the body 12 are coated with thin layers 22, 24 as
`shown in FIG. Each of the layers 22, 24 is composed of
`?nely divided metal such as platinum, palladium, gold,
`50
`etc. mixed with a ceramic material, preferrably of the
`same or a substantially similar composition as that of the
`ceramic body 12, in a conventional organic liquid or
`paste form. The layers 22, 24 are usually not more than
`0.001 inches thick and may cover the entire sides 18, 20,
`and overlap unto the body 12 or only parts of these sides
`suf?ciently to cover an exposed end or edge 21, 23 of
`the respective electrode 14, 16.
`At this stage, the capacitor 10' shown in FIG. 5 may
`be ?red to cure the ceramic block on body 12, elec
`trodes 14, 16 and layers 22, 24 to form the monolithic
`,integral capacitor structure 10" shown in FIG. 7. Then
`at a next stage, solder 26 may be applied to outer sides
`of the cured termination layers 22', 24', and leads 28
`applied to complete the capacitor 10".
`As an alternative, the layers 22, 24 may each be
`coated with thin layers‘ 25 and 25', shown in FIG. 6,
`prior to co?ring, in order to improve the performance
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`vided metallic material and having exposed edges
`1. A process for applying a plurality of conductive
`at spaced sides of said body;
`paths on the exterior of a ceramic component having an
`applying a ?rst termination layer to said sides of said
`unsintered ceramic body comprising the steps of:
`body to cover and connect electrically said ex
`applying said paths to said body said paths being
`posed edges of said electrodes, said layer being
`composed of only a ?nely divided metal, and ?nely
`composed of a mixture of ?nely divided metal,
`divided ceramic particles substantially the same as
`?nely divided ceramic particles, and a liquid or
`the ceramic of said body, in an organic carrier;
`ganic carrier;
`applying a termination layer over said paths, said
`applying a second termination layer onto said ?rst
`termination layer having ?nely divided metal in a
`layer, said second layer being composed of ?nely
`liquid carrier and ?nely divided ceramic particles
`divided metal and a liquid organic carrier; and
`of substantially the same ceramic as that of said
`cofiring said body, electrodes, ?rst and second layers
`body; and
`to integrate the same into a monolithic, integral
`co?ring said body, said paths and said termination
`unit, so that said integrated ?rst and second layers
`layer to integrate the same into a monolithic inte
`form conductive terminations of said electrodes.
`gral unit.
`11. A process as de?ned in claim 9, wherein said
`2. A process as de?ned in claim 1 wherein said ce
`ceramic particles of said ?rst termination layer are sub
`ramic component is a capacitor.
`stantially in the range of 10% to 60% by volume of said
`3. A process as de?ned in claim 1 wherein said con
`mixture exclusive of said carrier, to insure that said ?rst
`ductive paths are composed of a ceramic to metal com»
`and second layers integrate completely with each other
`20
`position substantially in the range of 10% to 60% by
`and with said body and said electrodes upon being ?red.
`volume.
`12. A process as de?ned in claim 9 wherein said sec
`4. A process as de?ned in claim 1 wherein said ce
`ond termination layer contains ceramic particles up to
`ramic component is a resistor and and said conductive
`60% by volume exclusive of said carrier.
`paths are composed of a ceramic to metal composition
`13. A process as de?ned in claim 9, comprising the
`further step of attaching leads to said conductive termi
`substantially in the range of 30% to 75% by volume.
`nations to complete said capacitor.
`5. A process as de?ned in claim 1 wherein said ?nely
`14. A process of manufacturing capacitors compris
`divided ceramic of said paths differs from said body
`ing of steps of:
`through the use of ?ux compounds and said paths are
`making a body from an assembly of strips of unsin
`composed of a ceramic to metal composition substan
`tered ceramic material containing spaced ?rst lay
`tially in the range of 2% to 10% by volume.
`ers of ?nely divided metallic material;
`6. A process of manufacturing a capacitor, compris
`under?ring said body to coalesce particles and re
`ing the steps of:
`move the binder;
`making a body of unsintered ceramic material con
`cutting said body to form a multiplicity of blocks
`taining thin spaced electrodes composed of ?nely
`with said ?rst layer constituting electrodes with
`divided metallic material having exposed edges at
`edges exposed at sides of said blocks;
`spaced sides of said body;
`applying conductive second layers to sides of each of
`applying a conductive layer to said spaced sides of
`said blocks to cover and connect electrically said
`said body to cover and connect electrically said
`exposed edges of said electrodes, said second layers
`40
`exposed edges of said electrodes, said layer being
`being composed of a only a mixture of ?nely di
`comprised of a mixture,said mixture composed of
`vided metal, ?nely divided ceramic particles, and a
`only a ?nely divided metal, ?nely divided ceramic
`liquid organic carrier; and
`particles, and an organic liquid carrier; and
`cofning said block, electrodes and second layers to
`co?ring said body, electrodes and layers to integrate
`integrate the same into a monolithic, integral unit,
`the same into a monolithic, integral unit, so that
`and so that said second layers form conductive
`said layers form conductive terminations of said
`terminations of said electrodes.
`electrodes.
`15. A process as de?ned in claim 14, comprising the
`7. A process as de?ned in claim 5 wherein said ce
`further step of applying to said second layers, prior to
`ramic of said mixture is substantially the same as the
`co?ring, third layers comprised of metallic material to
`ceramic of said body.
`render leads readily attachable to said third layers.
`8. A process as de?ned in claim 5, wherein said ce
`16. A process a de?ned in claim 14, wherein said
`ramic particles are substantially in the range of 10% to
`ceramic particles of said second layers are substantially
`60% by volume of said mixture exclusive of said carrier,
`in the range of 10% to 60% by volume of said mixture
`to insure that said layers integrate completely with said
`exclusive of said carrier to insure that said electrodes
`body and electrodes upon being ?red.
`and said second layers integrate completely with each
`9. A process as de?ned in claim 5, comprising the
`other and with said block upon being co?red.
`further step of attaching leads to said conductive termi
`17. A process as de?ne in claim 14 wherein said third
`metallic layers include ?nely divided ceramic particles.
`nations to complete said capacitor.
`10. A process of manufacturing a capacitor, compris
`18. A process as de?ned in claim 14, comprising the
`further step of attaching leads to said second layers to
`ing the steps of:
`complete said capacitor.
`making a body of unsintered ceramic material con
`taining spaced electrodes composed of ?nely di
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