CA1180779A - Ceramic capacitor and method of making same - Google Patents
Ceramic capacitor and method of making sameInfo
- Publication number
- CA1180779A CA1180779A CA000401648A CA401648A CA1180779A CA 1180779 A CA1180779 A CA 1180779A CA 000401648 A CA000401648 A CA 000401648A CA 401648 A CA401648 A CA 401648A CA 1180779 A CA1180779 A CA 1180779A
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- CA
- Canada
- Prior art keywords
- capacitor
- layer
- layers
- ceramic
- accordance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/228—Terminals
- H01G4/232—Terminals electrically connecting two or more layers of a stacked or rolled capacitor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/228—Terminals
- H01G4/232—Terminals electrically connecting two or more layers of a stacked or rolled capacitor
- H01G4/2325—Terminals electrically connecting two or more layers of a stacked or rolled capacitor characterised by the material of the terminals
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Ceramic Capacitors (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
Abstract
ABSTRACT OF THE INVENTION
The present invention is directed to an improved ceramic capacitor and method of making same and relates more particularly to a means for terminating an essentially conventional ceramic capacitor resulting in reduced production costs and a superior capacitor product. The invention is characterized by the capacitor terminations being formed by a thin film deposition method and more particularly by a sputtering deposit, the sputtering deposition being preferably preceeded by a sputter etching step. In addition to eliminating or reducing the quantity of silver or like noble metals required in the manufacturing process, the sputtering, which preferably employs a deposited nickel or nickel alloy film, provides an effective termination for the capacitor and structurally reinforces the termination areas of the capacitor whereby the same are rendered less susceptible to delamination.
The present invention is directed to an improved ceramic capacitor and method of making same and relates more particularly to a means for terminating an essentially conventional ceramic capacitor resulting in reduced production costs and a superior capacitor product. The invention is characterized by the capacitor terminations being formed by a thin film deposition method and more particularly by a sputtering deposit, the sputtering deposition being preferably preceeded by a sputter etching step. In addition to eliminating or reducing the quantity of silver or like noble metals required in the manufacturing process, the sputtering, which preferably employs a deposited nickel or nickel alloy film, provides an effective termination for the capacitor and structurally reinforces the termination areas of the capacitor whereby the same are rendered less susceptible to delamination.
Description
1070-1~5 ~L18~77~
TITLE: IMPROVED CERAMIC CAPACITOR AI~D
METHOD OF MAKING SAME
-BACK~ROUND OF THE INVENTION
F~eld of the Inventi_ The present in~enti~n relates t~ ceramic capacitors and more part~cularly pertains to an improved ceramic capacitOr and - method of m~king same. ~ore particularly, this invention relates to a novel method of effecting termination of a fired ceramic : : c2pacitor device and to the resultant impr~ved capac itor dèvice.
The Prior Art The mznufacture ~f ceramic capacitors is described generally in one or more o~ the following U.S. Letters Patent:
,:
3,00~,1S7 October 10, 1961 3,235~39 February 22, 1966 : Generally speaking such meth~d involves forming a shee~
r sheet.c of green ceramic comprising in essence cer~mic ~: p~wder material in an ~rganic binder. me sheets ~re imprinte~
by ~ilk-screening cr ~ similar prccess wlth an ink incorporat~n~
^O mètal particles recistant t~ disinte~ration ~t high ternperatures.
mult~plicity of such sheets are stacXed wi~h the lmprinted ~r electrode form~ng zrezs in p~rti~l registry. ~ne st~cXed sheet,s are then c~t into discrete i~crem~tS alo~g se~erance l~nes~ such that the ~ncrements expose altern~te electrode .~ .
~.
7~7~
12yers at opposite edge margins.
The increments are Dext treated by heating to a first tempçrature ~or a time sufficien~ to burn off the organic binder materials. Heatin~ is then continued &t a higher temperature to flre the cerami~ and to cause the electrode imprinted areas to ~orm conductive metallic electrodes between the ceram~c layers.
The resultsnt ceramic capacit3r subcomponents must now be terminated i e. a conductive connection must be effective between the edges of the various electrode layers exposed at ~he opposite margins of the capacitor preform Hereto~ore, such connections have been effected by applying a silver containing paste to the respective margins and heating the capacitor to cause the silver ~o si~ter whereby ~he electrodes at the respective margins are interconnected.
In some cases, conductive leads are ~oldered to the silver terminations. More typically, particularly with capacitor~ of small value, the capacitors are coated with a protective insulaking coat in all areas except ~he termination ~nd are shipped for use in such condition.
Obviously, the cost of ~uch silver terminated leadless capac~tor~ ~s substOntially increased a~ a result of the necessi~y of employln~ ccnsiderable 2mounts G~ silver in effec~ing ~ermination. The silver ter~na~eZ capacitors are fur~her disadv~ntegeous, in th~t, ~Ihen ~ soldered connec~ion i~ made to the silver termin~tion ~he silver tends to disolve ~ i !
)779 and flow into the lead-tin ~lloy of the solder Unless such soldering is carefully erfected, the sllver of the termination joint may flo~ so completely into the solder as to partially cr co~pletely lose electrical contact I~Jith the electrode layers e A ~urther disadvantage of conventionally terminated ceramic capacitors is that the E ilver termination is of little structural value in rein~orcing the capac~tor against delamination since the sole or principle adherance of the silver is to the electrode materials per se and not the ceramic.
In order t~ provide a degree of reinforcing effect certain of the silver terminating pastes may embody glass frit material which forms a partial bond to the ceramic. However, the utilization of glas6 frit material engenders other diff~culties and manufacturing complications including the requirement cf ~; heating the units up to a temperature sufficiently high to ~; melt the fxit component of the silver paste. The high heat requirements of the procedure in addition to being energy -asteful al~o increase the chances tha~ tne capacitors will be 2G 22maged in the cource of reheating. Finally, the conductivity of the silver-,rit termination paste in inIerior to a pure metallic conductive material.
Y OF THE ~V~TIOIY
~ , The present invention may be su~marized as directed to an improved ~ethod of manufacturin~ ceramic capaci~ors and ~i;
118~)~779 an improved resultant capacitor In accordance with the tnethod of the invention a conventional chip cap~citor which has been fired is loaded into a j~g or like m~s~ing device which exposes only the edge margin surfaces of the capacitor which incorporates the edge portions of ~he electrodes. The masked capacitors are placed in a sputtering apparatus kno~
per se wherein heavy gas ions are impacted against a target material re~ul~ing in atoms of the target material being bombarded against ~he exposed surface of the capacitor.
Optionally, but preferably, the exposed surface of the capacitor, prior to sputtering, is itself R.~. suptter etched i.e the heavy gas ions are im~ cted directly against the exposed surface ~f the capacitor. Such ~putter etching in addition to removlng the oxides or impurities at the surface provides a rugose or corrugated surface for the subsequent sputter applied metallic layer.
In acc3rdance with the method more than one sputter applied metallic layer may be deposlted on the capacitor surface in accordance with the intended end use of tne capacitor. By way of example a satisfactory capacitor termination may be effected by sputter deposi~ing 8 nickel layer, an alloy of nickel vanadium, a copper layer etc. Optionally, a chromium layer may first be deposited t~ improve adhesion followed by a nickel ~r nickel venadium sputter applied layer. To facilitate subsequent soldering a very thin silver layer may be applied over ~he nickel e.g. in ~he order of .1 micron.
)77~
The capacitor in accordance ~ith the-invention provides a highly des~rsble structure ln that the absence of ~ilver at the junction with the capaci~or electrodes eliminates the possibility that electrode contact will be lost in the course of soldering Subs~antial cost reductions are achieved by eliminating the use of silver terminations Additionally ; and importantly, the sputter deposited l~yer, particul2rly lf th~ edge portion of the capacitor has been previously sputter etched, provides a coatin~ which adheres strongly both to the electrodes and to the intervening ceramic spaces whereby any tendency of the capacitor to delaminate along .
the cleavage lines defined by the ceramic-electrode inter'zces is substantially reduced or eliminated. The mechanical reinforcing effect of the sputter deposited terminations enables the final insulating or incapsulating coating, if used, to function merely as an electrical isolation rather than as a mechanical reinforcement of the capacitor. Thus the overall size or bulk of the capacitor may be reduced.
It is accordingly an object of the invention to provide an improved method of fabricating 2 ceramic czpacitor and more particularly an improved method of ~erminating a conventiena ceram~c capacitor. A ~urther object ~f the invent~on ls the provision o~ a novel termination me~nod for ceramic capacitors wnich el~minates the use of s~lver or other noble metalc a~ the interface with ~he capacitor electrodes. Still a fur~her object of the invention is the provision of ~ method o~
fabr~cating ceramlc capacitors which includes the step of sputter etch~ng the electrode containing margin of the capacitor to clea~ the same and provide an etched or pebbled sur~ace and thereafter sputter depositing a thin film of conductive metal which simultaneously electrically uni~es the e~posed electrode~ and f~rms a unifying or mechanically rigidifying influence at the capacitor margin.
A further object of ~he invention is the provision of a ceramic capacitor having termination which are free of silver at the interface with the electrodes. A further object ~f the ~nvention is the provision of a capacitor of the type described wherein the termlnation layer functions as a mechanical reinforcement against delamination of the capacitor.
Still other and further object of the invention will appear herein of be hereinafter pointed out in connection with the description of the dra~ings wherein.
Fig. 7 is a vertical sectional view diagramatic in na~ure of a ceramic capacitor prepaxatory to termination.
Fig. 2 is a vielY similar to Fig. 1 showing the capacitor in a masking apparatus.
Fig. 3 is a diagramatic view of the masked capacitor in ~he course of sputter deposition treatment, Fig. ~ A, 4 B and 4 C are diagramOtic sequential views resp~ctively of an untreated capacitor~ a capacitor which is : sputter etched on i~s upper surface, a~d of ~ capacitor having ; ~ spu~ter deposited layer covering the sputter etched sur~ace~
As used herein khe term sputter coating, sputter ; deposlting or spu~tering shall mean the gas ion disentegration of a cathode target and consequent deposition of atoms removed from the target as a layer on the capacitor marg~n having exposed electrode edges.
The term sputter etching or sputter etched shall be deemed to mean a procedure whereby cathode and gas ions are directed agalnst the capacitor margins to be terminated in an R.F. field.
Turning now to the drawings there is shown in Fig. 1 in diagramatic form a ceramic capacitor conventional in ~ ; nature and fabricated f'or instance in accordance ~ith the : disclosures of U.S. Patent 3,235,939. The capacitor 10 : comprises a mult iplic ity of ceramic la~ers 11 defining the dielectric components of the capacitors, the layers 11 being ~ ~
separated by intervening electrode layers 12 and 13.
As is convent~onal the electrode layers 12 and 13 extend for less th2n the entire length of the capacitor but overlap ~J
throu~hou~ the majority of their extent. As iE apparent from Fig. 1 the electrode layers 12 incorporate edge portions which are exposed at the margin 14 of the capacitor 10 whereas the electrodes 13 include edge portions exp~sed at the margin 1 o~ ~he capac~tor, In accordance ~ith the process ol the inven~l~n a ~,~ltiplicity ~ the capacitors 10 are loaded ~nto a die or 8a)~7~9 ~ig 16 (~ig.2) the funetion ~f which is ~o shleld all of the surfaces of the capacitor except the uppermost surface i-e, one or ~he other of the marginal surfaces 14 or 15. As depicted in Fig. 2 the marginal surface 14 of the capacitor ~s located uppermos~ in the mask of Jig 16~ It ~Jill accoralngly be apprec iated that the edge port ions of the . .
electrodes 12 are exposed in an upward direckion.
Although in the diagramatic views o~ the Figs. 1 through 3 the capacitors lO have been ~epicted 25 shielded 10 by individual pockets 17 of the masking device 16, . it will be understood khat a mutual shielding effect may be achieved by stacking ~ multiplicity of the capacitors in side by side relat ion O
-The shielded capacitors are next processed by sputter etching the uppermos~ ~urface or margin 14. While the sputter etching step is opti~nal such step is preferred, in that, ~n addition to the usual effect ~f cleaning the exposed surface~
the sputter etching step also provides a rugose or corrugated or pebbled impact area f~r the subsequently applied met211ic layer. The effect of spu~ter etching is diagrama~ically ~llustrated by a c~mparison Ol Fig. ~ A (unetched) with 4 (sputter etched~.
~ he cputter etched suxface l~ is next ~putter coated by p2S~ ing the same Deneath the target of a sputtering oevice.
Optl~nally7 but preferably, ~n in-line cputtering system such as a sys~em identified as the SERIES ~0 SPUTTERING DE-v~CE as 7~1t manufactured by Materials Research Corporation of Orangeburgh~ New York is employed. An inline sputtering system is advan~ageous in that it permits the capacitors to be progressively advanced beneath target areas o~
dif~erent compositions whereby a layer of a first sputter deposited material may be formed directly over the surface 14 and thereafter a second sputter deposited layer ma.y be formed over the first layer. Illustratively, a nickel-va~a.dium alloy layer may first be sputter deposited by advancing the capa.citor benea.th an appropriate target ma~erial,~he nickel or nickel-~a.nadium layer being therea~ter thin coated with a silver layer by advancing the same beneath a silver target member. It is also desira.ble under rertain clrcumstances i.e. for improved adhesion~to first effect ; the deposi~on of a thin chromium layer and thereafter coat the chromium layer by sputter deposition wlth a nickel.or nickel-vanadium layer, such procedures being readily carried out in an inline sputtering system by progressively advancing the capacitors beneath suitzbly s~lec~ed targe~ materials.
The sputter depofiition is con~inued in a manner kno~
per sP un~il the ~esired layer build up is achieved. Referring ; to Fig. 4 ~ i~ will be apparent ~hat the sputter deposited layer or layer~ 18 ~Jill define a cohesive mass of layer~ the lowermost surface ol which is strongly adheren~ to an~ enters ~;ith~n the recesses~ interstices or pores 19 formed by the ~pu~ter etching procedure. m e layer 18 provides an effective 5- .
)7~9 electrical and mechanical. connectio~ to the electrodes 12 , and a mechanical connection to exposed ceramic comp~nents at the sur~ace 14. The layer 18 thus provides a termina~ion and a mech~nical reinforcement of the edge 14 minimizing the possibillty of cleavage of the capa.citor along the lines of ~nterface be~een the ceramic and electrodes.
It will be a.ppreciated that the etching and spu~tering procedures described are repeated with the edge portion 15 of the ceramic exposed to the target whereby a second termination layer 20 is formed over the edge 15.
: The termina.ted capacitor is n3~q ready for use.
Optionally~ an insula.ting c~ating may be applied over all portions of the capacitor except the terminations.
-By way of exa.mple, and ~or purposes of compliance with the requirements o~ the patent laws, there will now be described the operating parameters o~ a specific embodiment of the invention it b~ing understood that neither the ~ materials nor the specific deta.ils ~ such de~cription shall :: be cons~dered limitative~
In accordance with the invent.ion ~ multiplicity of chips are loca~ed ~n a f~xture with the termination ends exposed in a upward d ~rect ion. The loa~ed f ixture is placed in a vacuum l~ad lock which iS pumped t~ a pressure of less than 50 X 10 ~ torr prior to introducin6 the f~xture into the main vacuum sput~ering chamber. ~ne loaded fixture is m~ved to aD R.F. sputter etching station wherein ~hP pressure - ;
~ 7 ~
is le~s than 5 X 10-6 torr. A high purity argon gas , is introduced lnto the et~hing chamber to achieve a pressure of ab~ut 10 X 10-3 torr. The parts having a surface area of approximately 311 millimeters square are sputter etched for 30 seconds at a power level of 1.4 kilowatt. The fixture carrying the etched capacltors is then traversed to a ~tation wher~ a .12 micr~meter thickness film is deposlted over the termination end~ m e film may comprise pure nickel or an alloy containing by weight 93 ~ nickel , ~s~ .
and ~ % vanadium~ Sputtering is effected at a power level of 4.2 kilowatts and a scan speed of 10.2 millimeters per second across the target area. The sputtering is preformed in a argon gas environment at a pressure 10 X 10-3 torr.
The procedure is repeated to effect etching and coa~ing of the opp~site termination-s-urface o~ -the-capacitors, Where direct nickel or nickel-vanadium coatings are eflected,coating thickness in the range offrom ~12 to 05 micrometers has been found to be optimum, Where a chr~mium substrate ~s used for high adhesion, layer thicknesses in the range ~f ,02 to .05 micr~meters ~ave been found preferred. As previously no$ed s~here direct solder~ng to the terminations is anticipated a very thin coating of silver i.e. of the magnitude of ab~uk .1 m~cron is desirably ~dded. I~ will be ob~erved that such quantity of silver ~s orly ~ very small fraction ~f the amount ~ypically used to terQinate a capacitor by eonventional methods.
'79 ~ rom the ~oregoing it will be perceived that there is provided ln a.ccordance with the present inventiorl c new and novel method of manufactur~ng ceramic ca.pacitors characterized in that the termination step is effected by sputter deposition prefera.hly follo~.~ng spu~er etching. It sJill further be perceived that the resultant unique capacitor may be ec~nomic~lly manufactured and ls uniquely strong and ~ree ~rom the tendency toward ~ilver leaching during ~oldering which is characteristic of convent~onal silver terminated capacitors.
A~ w~l be apparent to those skilled in ~he art, numerous changes may be effected particularly in the selection of materials, layer thicknesses and treatment p~rameters for el~ecting etching and coating. Accordingly~
the invention i~!,.to.;b.e.broadly constr~uedj~rithin the scope~
o, the appended claims.
J
. -12-
TITLE: IMPROVED CERAMIC CAPACITOR AI~D
METHOD OF MAKING SAME
-BACK~ROUND OF THE INVENTION
F~eld of the Inventi_ The present in~enti~n relates t~ ceramic capacitors and more part~cularly pertains to an improved ceramic capacitOr and - method of m~king same. ~ore particularly, this invention relates to a novel method of effecting termination of a fired ceramic : : c2pacitor device and to the resultant impr~ved capac itor dèvice.
The Prior Art The mznufacture ~f ceramic capacitors is described generally in one or more o~ the following U.S. Letters Patent:
,:
3,00~,1S7 October 10, 1961 3,235~39 February 22, 1966 : Generally speaking such meth~d involves forming a shee~
r sheet.c of green ceramic comprising in essence cer~mic ~: p~wder material in an ~rganic binder. me sheets ~re imprinte~
by ~ilk-screening cr ~ similar prccess wlth an ink incorporat~n~
^O mètal particles recistant t~ disinte~ration ~t high ternperatures.
mult~plicity of such sheets are stacXed wi~h the lmprinted ~r electrode form~ng zrezs in p~rti~l registry. ~ne st~cXed sheet,s are then c~t into discrete i~crem~tS alo~g se~erance l~nes~ such that the ~ncrements expose altern~te electrode .~ .
~.
7~7~
12yers at opposite edge margins.
The increments are Dext treated by heating to a first tempçrature ~or a time sufficien~ to burn off the organic binder materials. Heatin~ is then continued &t a higher temperature to flre the cerami~ and to cause the electrode imprinted areas to ~orm conductive metallic electrodes between the ceram~c layers.
The resultsnt ceramic capacit3r subcomponents must now be terminated i e. a conductive connection must be effective between the edges of the various electrode layers exposed at ~he opposite margins of the capacitor preform Hereto~ore, such connections have been effected by applying a silver containing paste to the respective margins and heating the capacitor to cause the silver ~o si~ter whereby ~he electrodes at the respective margins are interconnected.
In some cases, conductive leads are ~oldered to the silver terminations. More typically, particularly with capacitor~ of small value, the capacitors are coated with a protective insulaking coat in all areas except ~he termination ~nd are shipped for use in such condition.
Obviously, the cost of ~uch silver terminated leadless capac~tor~ ~s substOntially increased a~ a result of the necessi~y of employln~ ccnsiderable 2mounts G~ silver in effec~ing ~ermination. The silver ter~na~eZ capacitors are fur~her disadv~ntegeous, in th~t, ~Ihen ~ soldered connec~ion i~ made to the silver termin~tion ~he silver tends to disolve ~ i !
)779 and flow into the lead-tin ~lloy of the solder Unless such soldering is carefully erfected, the sllver of the termination joint may flo~ so completely into the solder as to partially cr co~pletely lose electrical contact I~Jith the electrode layers e A ~urther disadvantage of conventionally terminated ceramic capacitors is that the E ilver termination is of little structural value in rein~orcing the capac~tor against delamination since the sole or principle adherance of the silver is to the electrode materials per se and not the ceramic.
In order t~ provide a degree of reinforcing effect certain of the silver terminating pastes may embody glass frit material which forms a partial bond to the ceramic. However, the utilization of glas6 frit material engenders other diff~culties and manufacturing complications including the requirement cf ~; heating the units up to a temperature sufficiently high to ~; melt the fxit component of the silver paste. The high heat requirements of the procedure in addition to being energy -asteful al~o increase the chances tha~ tne capacitors will be 2G 22maged in the cource of reheating. Finally, the conductivity of the silver-,rit termination paste in inIerior to a pure metallic conductive material.
Y OF THE ~V~TIOIY
~ , The present invention may be su~marized as directed to an improved ~ethod of manufacturin~ ceramic capaci~ors and ~i;
118~)~779 an improved resultant capacitor In accordance with the tnethod of the invention a conventional chip cap~citor which has been fired is loaded into a j~g or like m~s~ing device which exposes only the edge margin surfaces of the capacitor which incorporates the edge portions of ~he electrodes. The masked capacitors are placed in a sputtering apparatus kno~
per se wherein heavy gas ions are impacted against a target material re~ul~ing in atoms of the target material being bombarded against ~he exposed surface of the capacitor.
Optionally, but preferably, the exposed surface of the capacitor, prior to sputtering, is itself R.~. suptter etched i.e the heavy gas ions are im~ cted directly against the exposed surface ~f the capacitor. Such ~putter etching in addition to removlng the oxides or impurities at the surface provides a rugose or corrugated surface for the subsequent sputter applied metallic layer.
In acc3rdance with the method more than one sputter applied metallic layer may be deposlted on the capacitor surface in accordance with the intended end use of tne capacitor. By way of example a satisfactory capacitor termination may be effected by sputter deposi~ing 8 nickel layer, an alloy of nickel vanadium, a copper layer etc. Optionally, a chromium layer may first be deposited t~ improve adhesion followed by a nickel ~r nickel venadium sputter applied layer. To facilitate subsequent soldering a very thin silver layer may be applied over ~he nickel e.g. in ~he order of .1 micron.
)77~
The capacitor in accordance ~ith the-invention provides a highly des~rsble structure ln that the absence of ~ilver at the junction with the capaci~or electrodes eliminates the possibility that electrode contact will be lost in the course of soldering Subs~antial cost reductions are achieved by eliminating the use of silver terminations Additionally ; and importantly, the sputter deposited l~yer, particul2rly lf th~ edge portion of the capacitor has been previously sputter etched, provides a coatin~ which adheres strongly both to the electrodes and to the intervening ceramic spaces whereby any tendency of the capacitor to delaminate along .
the cleavage lines defined by the ceramic-electrode inter'zces is substantially reduced or eliminated. The mechanical reinforcing effect of the sputter deposited terminations enables the final insulating or incapsulating coating, if used, to function merely as an electrical isolation rather than as a mechanical reinforcement of the capacitor. Thus the overall size or bulk of the capacitor may be reduced.
It is accordingly an object of the invention to provide an improved method of fabricating 2 ceramic czpacitor and more particularly an improved method of ~erminating a conventiena ceram~c capacitor. A ~urther object ~f the invent~on ls the provision o~ a novel termination me~nod for ceramic capacitors wnich el~minates the use of s~lver or other noble metalc a~ the interface with ~he capacitor electrodes. Still a fur~her object of the invention is the provision of ~ method o~
fabr~cating ceramlc capacitors which includes the step of sputter etch~ng the electrode containing margin of the capacitor to clea~ the same and provide an etched or pebbled sur~ace and thereafter sputter depositing a thin film of conductive metal which simultaneously electrically uni~es the e~posed electrode~ and f~rms a unifying or mechanically rigidifying influence at the capacitor margin.
A further object of ~he invention is the provision of a ceramic capacitor having termination which are free of silver at the interface with the electrodes. A further object ~f the ~nvention is the provision of a capacitor of the type described wherein the termlnation layer functions as a mechanical reinforcement against delamination of the capacitor.
Still other and further object of the invention will appear herein of be hereinafter pointed out in connection with the description of the dra~ings wherein.
Fig. 7 is a vertical sectional view diagramatic in na~ure of a ceramic capacitor prepaxatory to termination.
Fig. 2 is a vielY similar to Fig. 1 showing the capacitor in a masking apparatus.
Fig. 3 is a diagramatic view of the masked capacitor in ~he course of sputter deposition treatment, Fig. ~ A, 4 B and 4 C are diagramOtic sequential views resp~ctively of an untreated capacitor~ a capacitor which is : sputter etched on i~s upper surface, a~d of ~ capacitor having ; ~ spu~ter deposited layer covering the sputter etched sur~ace~
As used herein khe term sputter coating, sputter ; deposlting or spu~tering shall mean the gas ion disentegration of a cathode target and consequent deposition of atoms removed from the target as a layer on the capacitor marg~n having exposed electrode edges.
The term sputter etching or sputter etched shall be deemed to mean a procedure whereby cathode and gas ions are directed agalnst the capacitor margins to be terminated in an R.F. field.
Turning now to the drawings there is shown in Fig. 1 in diagramatic form a ceramic capacitor conventional in ~ ; nature and fabricated f'or instance in accordance ~ith the : disclosures of U.S. Patent 3,235,939. The capacitor 10 : comprises a mult iplic ity of ceramic la~ers 11 defining the dielectric components of the capacitors, the layers 11 being ~ ~
separated by intervening electrode layers 12 and 13.
As is convent~onal the electrode layers 12 and 13 extend for less th2n the entire length of the capacitor but overlap ~J
throu~hou~ the majority of their extent. As iE apparent from Fig. 1 the electrode layers 12 incorporate edge portions which are exposed at the margin 14 of the capacitor 10 whereas the electrodes 13 include edge portions exp~sed at the margin 1 o~ ~he capac~tor, In accordance ~ith the process ol the inven~l~n a ~,~ltiplicity ~ the capacitors 10 are loaded ~nto a die or 8a)~7~9 ~ig 16 (~ig.2) the funetion ~f which is ~o shleld all of the surfaces of the capacitor except the uppermost surface i-e, one or ~he other of the marginal surfaces 14 or 15. As depicted in Fig. 2 the marginal surface 14 of the capacitor ~s located uppermos~ in the mask of Jig 16~ It ~Jill accoralngly be apprec iated that the edge port ions of the . .
electrodes 12 are exposed in an upward direckion.
Although in the diagramatic views o~ the Figs. 1 through 3 the capacitors lO have been ~epicted 25 shielded 10 by individual pockets 17 of the masking device 16, . it will be understood khat a mutual shielding effect may be achieved by stacking ~ multiplicity of the capacitors in side by side relat ion O
-The shielded capacitors are next processed by sputter etching the uppermos~ ~urface or margin 14. While the sputter etching step is opti~nal such step is preferred, in that, ~n addition to the usual effect ~f cleaning the exposed surface~
the sputter etching step also provides a rugose or corrugated or pebbled impact area f~r the subsequently applied met211ic layer. The effect of spu~ter etching is diagrama~ically ~llustrated by a c~mparison Ol Fig. ~ A (unetched) with 4 (sputter etched~.
~ he cputter etched suxface l~ is next ~putter coated by p2S~ ing the same Deneath the target of a sputtering oevice.
Optl~nally7 but preferably, ~n in-line cputtering system such as a sys~em identified as the SERIES ~0 SPUTTERING DE-v~CE as 7~1t manufactured by Materials Research Corporation of Orangeburgh~ New York is employed. An inline sputtering system is advan~ageous in that it permits the capacitors to be progressively advanced beneath target areas o~
dif~erent compositions whereby a layer of a first sputter deposited material may be formed directly over the surface 14 and thereafter a second sputter deposited layer ma.y be formed over the first layer. Illustratively, a nickel-va~a.dium alloy layer may first be sputter deposited by advancing the capa.citor benea.th an appropriate target ma~erial,~he nickel or nickel-~a.nadium layer being therea~ter thin coated with a silver layer by advancing the same beneath a silver target member. It is also desira.ble under rertain clrcumstances i.e. for improved adhesion~to first effect ; the deposi~on of a thin chromium layer and thereafter coat the chromium layer by sputter deposition wlth a nickel.or nickel-vanadium layer, such procedures being readily carried out in an inline sputtering system by progressively advancing the capacitors beneath suitzbly s~lec~ed targe~ materials.
The sputter depofiition is con~inued in a manner kno~
per sP un~il the ~esired layer build up is achieved. Referring ; to Fig. 4 ~ i~ will be apparent ~hat the sputter deposited layer or layer~ 18 ~Jill define a cohesive mass of layer~ the lowermost surface ol which is strongly adheren~ to an~ enters ~;ith~n the recesses~ interstices or pores 19 formed by the ~pu~ter etching procedure. m e layer 18 provides an effective 5- .
)7~9 electrical and mechanical. connectio~ to the electrodes 12 , and a mechanical connection to exposed ceramic comp~nents at the sur~ace 14. The layer 18 thus provides a termina~ion and a mech~nical reinforcement of the edge 14 minimizing the possibillty of cleavage of the capa.citor along the lines of ~nterface be~een the ceramic and electrodes.
It will be a.ppreciated that the etching and spu~tering procedures described are repeated with the edge portion 15 of the ceramic exposed to the target whereby a second termination layer 20 is formed over the edge 15.
: The termina.ted capacitor is n3~q ready for use.
Optionally~ an insula.ting c~ating may be applied over all portions of the capacitor except the terminations.
-By way of exa.mple, and ~or purposes of compliance with the requirements o~ the patent laws, there will now be described the operating parameters o~ a specific embodiment of the invention it b~ing understood that neither the ~ materials nor the specific deta.ils ~ such de~cription shall :: be cons~dered limitative~
In accordance with the invent.ion ~ multiplicity of chips are loca~ed ~n a f~xture with the termination ends exposed in a upward d ~rect ion. The loa~ed f ixture is placed in a vacuum l~ad lock which iS pumped t~ a pressure of less than 50 X 10 ~ torr prior to introducin6 the f~xture into the main vacuum sput~ering chamber. ~ne loaded fixture is m~ved to aD R.F. sputter etching station wherein ~hP pressure - ;
~ 7 ~
is le~s than 5 X 10-6 torr. A high purity argon gas , is introduced lnto the et~hing chamber to achieve a pressure of ab~ut 10 X 10-3 torr. The parts having a surface area of approximately 311 millimeters square are sputter etched for 30 seconds at a power level of 1.4 kilowatt. The fixture carrying the etched capacltors is then traversed to a ~tation wher~ a .12 micr~meter thickness film is deposlted over the termination end~ m e film may comprise pure nickel or an alloy containing by weight 93 ~ nickel , ~s~ .
and ~ % vanadium~ Sputtering is effected at a power level of 4.2 kilowatts and a scan speed of 10.2 millimeters per second across the target area. The sputtering is preformed in a argon gas environment at a pressure 10 X 10-3 torr.
The procedure is repeated to effect etching and coa~ing of the opp~site termination-s-urface o~ -the-capacitors, Where direct nickel or nickel-vanadium coatings are eflected,coating thickness in the range offrom ~12 to 05 micrometers has been found to be optimum, Where a chr~mium substrate ~s used for high adhesion, layer thicknesses in the range ~f ,02 to .05 micr~meters ~ave been found preferred. As previously no$ed s~here direct solder~ng to the terminations is anticipated a very thin coating of silver i.e. of the magnitude of ab~uk .1 m~cron is desirably ~dded. I~ will be ob~erved that such quantity of silver ~s orly ~ very small fraction ~f the amount ~ypically used to terQinate a capacitor by eonventional methods.
'79 ~ rom the ~oregoing it will be perceived that there is provided ln a.ccordance with the present inventiorl c new and novel method of manufactur~ng ceramic ca.pacitors characterized in that the termination step is effected by sputter deposition prefera.hly follo~.~ng spu~er etching. It sJill further be perceived that the resultant unique capacitor may be ec~nomic~lly manufactured and ls uniquely strong and ~ree ~rom the tendency toward ~ilver leaching during ~oldering which is characteristic of convent~onal silver terminated capacitors.
A~ w~l be apparent to those skilled in ~he art, numerous changes may be effected particularly in the selection of materials, layer thicknesses and treatment p~rameters for el~ecting etching and coating. Accordingly~
the invention i~!,.to.;b.e.broadly constr~uedj~rithin the scope~
o, the appended claims.
J
. -12-
Claims (13)
1. As a new article of manufacture a ceramic capacitor device comprising alternate layers of ceramic dielectric material, layers of electrode material interposed between said ceramic layers, alternate ones of said electrode layers having a first edge portion extending to and being exposed respectively at first and second opposite margins of said capacitor, the edges of said electrode layers opposite said first edge portions terminating short of said margins, said capacitor being characterized in that said first and second margins of said capacitor are coated by a sputter deposited metallic layer, said layer being bonded to the exposed ceramic components of said margins and to the exposed edge portions of said electrode layers whereby the layers exposed at said edges are electrically connected and the ceramic and electrode components of said edge portions are mechanically bonded, said deposited metallic layers in addition defining terminations of said capacitor.
2. A capacitor in accordance with claim 1 wherein said -margin portions have been sputter etched to provide a rugose surface prior to deposition of said metallic layer whereby the material or said sputter deposited layer enters the interstices in said ceramic and electrode materials to thereby form a destratification resistant bond with said layers as well as a mechanical and electrical bond to said exposed portions of said electrodes.
3. A capacitor in accordance with claim 2 wherein said layer comprises nickel.
4. A capacitor in accordance with claim 2 wherein said layer comprises chromium, the combination including a.
second sputter deposited metallic layer covering said first layer.
second sputter deposited metallic layer covering said first layer.
5. A capacitor in accordance with claim 4 wherein said second layer comprises nickel.
6. A capacitor in accordance with claim 3 and including a sputter deposited silver layer covering said nickel layer.
7. A capacitor in accordance with claim 6 wherein said silver layer is of a thickness of about .1 micron,
8. The method of manufacturing a ceramic capacitor device which includes interposing between alternate layers of a green ceramic, layers of electrode material, alternate ones of said electrode layers having a first edge portion extending to and being respectively at first and second opposite margins of said device, the edges of said electrode layers opposite said first edge portions terminating short of said margins, firing said green ceramic and, thereafter, sequentially positioning said first and then said second marginal portions of said fired capacitor within a sputtering zone in predetermined spaced relation to a metallic target cathode while shielding all but said marginal portion to be sputtered whereby an electrically conductive sputtered layer of target material is caused to be bonded to the ceramic and .
to the exposed electrode areas defining said marginal portion.
to thus electrically connect the electrode layers of the treat-treated margin said sputtered layers defining terminations of said capacitor.
to the exposed electrode areas defining said marginal portion.
to thus electrically connect the electrode layers of the treat-treated margin said sputtered layers defining terminations of said capacitor.
9. The method in accordance with claim 8 wherein said marginal portions are sputter etched in advance of sputter deposition of said layer to thereby define a rugose surface, the interstices of said surface being filled at least partially by the material of said layer.
10. The method in accordance with claim 9 wherein said layer comprises nickel.
11. The method in accordance with claim. 9 wherein said layer comprises chromium and said chromium layer is thereafter covered by a sputter deposited second metallic nickel layer.
12. The method in accordance with claim 9 wherein said layer comprises a nickel-vanadium alloy.
13. The method in accordance with claim 9 and including the step of sputter depositing a silver layer over said metallic layer,said silver layer having a thickness in the order of about .1 micron.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US30548881A | 1981-09-25 | 1981-09-25 | |
| US305,488 | 1981-09-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180779A true CA1180779A (en) | 1985-01-08 |
Family
ID=23181015
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000401648A Expired CA1180779A (en) | 1981-09-25 | 1982-04-26 | Ceramic capacitor and method of making same |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5864017A (en) |
| CA (1) | CA1180779A (en) |
| DE (1) | DE3224959A1 (en) |
| FR (1) | FR2513804B1 (en) |
| GB (1) | GB2106714B (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4584629A (en) * | 1984-07-23 | 1986-04-22 | Avx Corporation | Method of making ceramic capacitor and resulting article |
| DE3517631A1 (en) * | 1984-11-07 | 1986-05-07 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR PRODUCING ELECTRICAL PLASMAPOLYMER MULTILAYER CAPACITORS |
| FR2585174B1 (en) * | 1985-07-16 | 1987-11-27 | Eurofarad | PROCESS FOR PRODUCING A MULTI-LAYERED CAPACITIVE COMPONENT WITH CERAMIC DIELECTRIC OF THE CORDIERITY TYPE, AND COMPONENT THUS OBTAINED |
| DE3638286A1 (en) * | 1986-11-10 | 1988-05-11 | Siemens Ag | Electrical component, made of ceramic and having multilayer metallisation, and a method for its production |
| DE3638342A1 (en) * | 1986-11-10 | 1988-05-19 | Siemens Ag | Electrical component, made of ceramic and having multilayer metallisation, and a method for its production |
| US4741077A (en) * | 1987-05-15 | 1988-05-03 | Sfe Technologies | End terminations for capacitors |
| DE3725454A1 (en) * | 1987-07-31 | 1989-02-09 | Siemens Ag | ELECTRICAL MULTI-LAYER COMPONENT WITH A SINTERED, MONOLITHIC CERAMIC BODY AND METHOD FOR PRODUCING THE ELECTRICAL MULTI-LAYER COMPONENT |
| DE3873206D1 (en) * | 1987-07-31 | 1992-09-03 | Siemens Ag | FILLED LAYER COMPONENT WITH A SINTERED, MONOLITHIC CERAMIC BODY AND METHOD FOR THE PRODUCTION THEREOF. |
| JPH04357807A (en) * | 1991-06-04 | 1992-12-10 | Rohm Co Ltd | Laminated ceramic capacitor comprising many integrated capacitor items |
| EP0572151A3 (en) * | 1992-05-28 | 1995-01-18 | Avx Corp | Varistors with sputtered terminations and a method of applying sputtered teminations to varistors and the like. |
| US5565838A (en) * | 1992-05-28 | 1996-10-15 | Avx Corporation | Varistors with sputtered terminations |
| JP2967660B2 (en) * | 1992-11-19 | 1999-10-25 | 株式会社村田製作所 | Electronic components |
| JP3494431B2 (en) * | 1998-12-03 | 2004-02-09 | 株式会社村田製作所 | Manufacturing method of ceramic electronic component and ceramic electronic component |
| US7208396B2 (en) | 2002-01-16 | 2007-04-24 | Tegal Corporation | Permanent adherence of the back end of a wafer to an electrical component or sub-assembly |
| DE10317584B4 (en) * | 2003-04-16 | 2007-07-12 | Siemens Ag | Apparatus and method for manufacturing a device having a first body of steel and an insulator |
| WO2005035809A1 (en) | 2003-10-07 | 2005-04-21 | Nikko Materials Co., Ltd. | HIGH-PURITY Ni-V ALLOY, TARGET THEREFROM, HIGH-PURITY Ni-V ALLOY THIN FILM AND PROCESS FOR PRODUCING HIGH-PURITY Ni-V ALLOY |
| SE527949C2 (en) * | 2004-12-22 | 2006-07-18 | Abb Research Ltd | Method of producing a varistor |
| US8691057B2 (en) | 2008-03-25 | 2014-04-08 | Oem Group | Stress adjustment in reactive sputtering |
| US8482375B2 (en) | 2009-05-24 | 2013-07-09 | Oem Group, Inc. | Sputter deposition of cermet resistor films with low temperature coefficient of resistance |
| JP2023098301A (en) * | 2021-12-28 | 2023-07-10 | 株式会社村田製作所 | Electronic component and manufacturing method of electronic component |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE754574C (en) * | 1940-06-11 | 1953-01-19 | Lorenz C Ag | Stacked capacitor with easily breakable dielectric intermediate layers |
| NL169260C (en) * | 1971-04-16 | 1982-06-16 | Tam Ceramics Inc | METHOD OF MANUFACTURING SINTERED CERAMIC OBJECTS CONTAINING CONDUCTORS |
| US4102021A (en) * | 1975-10-06 | 1978-07-25 | Matsushita Electric Industrial Co., Ltd. | Method for making capacitors with plated terminals |
| JPS6029214B2 (en) * | 1977-07-11 | 1985-07-09 | 株式会社村田製作所 | Manufacturing method of multilayer capacitor |
-
1982
- 1982-04-26 CA CA000401648A patent/CA1180779A/en not_active Expired
- 1982-05-06 GB GB08213035A patent/GB2106714B/en not_active Expired
- 1982-06-28 JP JP57111413A patent/JPS5864017A/en active Pending
- 1982-07-03 DE DE19823224959 patent/DE3224959A1/en not_active Withdrawn
- 1982-07-15 FR FR8212393A patent/FR2513804B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3224959A1 (en) | 1983-04-14 |
| GB2106714B (en) | 1985-05-09 |
| FR2513804A1 (en) | 1983-04-01 |
| JPS5864017A (en) | 1983-04-16 |
| GB2106714A (en) | 1983-04-13 |
| FR2513804B1 (en) | 1986-09-05 |
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