CA1045221A - Method of making ceramic capacitor - Google Patents
Method of making ceramic capacitorInfo
- Publication number
- CA1045221A CA1045221A CA225,854A CA225854A CA1045221A CA 1045221 A CA1045221 A CA 1045221A CA 225854 A CA225854 A CA 225854A CA 1045221 A CA1045221 A CA 1045221A
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- sheet
- capacitors
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- sheets
- apertures
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A method of making single layer capacitors of relatively high capacitive value by applying a multi-pliclty of conductors to opposite sides of a first green ceramic sheet, applying additional green ceramic sheets on either side of the first sheet, laminating the sheets, scoring the lamination between the conductors, sintering the green ceramic into a monolithic structure, and snapping or breaking individual capacitors from the structure along the score lines.
A method of making single layer capacitors of relatively high capacitive value by applying a multi-pliclty of conductors to opposite sides of a first green ceramic sheet, applying additional green ceramic sheets on either side of the first sheet, laminating the sheets, scoring the lamination between the conductors, sintering the green ceramic into a monolithic structure, and snapping or breaking individual capacitors from the structure along the score lines.
Description
1~45ZZl S P ~ C I F I C A T I 0 N
This inventlon relatos to capacitors and mors partl-cularly relates to ceramic capacitors having a higher capacltance valu2, and a method of making the same.
The present invention is directed to capacitors which are of the single layer type, that is, include only two electrodes with a dlelectric spacing therebetween, where such capacitors are manufactured in multiple. At the present time, capacltors of the typo to which this invention relate3 are made with a flred ceramic dielectric which, after curing, - ls coated wlth a conductive substance on each side thereof.
The dlelectrlc ls then cut into indlvidual capacitors, leads applied, and the ceramic with conductive coating~
thereon encapsulated in an insulating material.
The production of this single layer type capacitor -by present methods results in a capacltor of limited capacitan~e value pr~marlly due to the thickness of the ceramlc dlelectrlc. The dlelectric must be made sufficiently thlck to have the required physical strength for handling both in a greenware state and in the fired state, and also whlch ls sufflclently thick so tha~ it will not unduly warp when the ceramlc greenware is fired.
The present lnventlon provides a new and improved method of manufacturlng single layer capacitors which enables the use of very thin ceramic spacers between the capacltor electrodes and permits a plurality of capacitors to be defined on a strlp of ceramlc greenware ln such a manner a~ to decrease the possibility of leakage between the capacitor electrodes.
Brlefly stated, the invention in one form thereof comprises the steps of defining a plurality of conductive _1, . ., 1C)45Z'~
patterns on opposite sides of a thin sheet of ceramic green-ware, covering said thin sheet on either side with other sheets of ceramic greenware having apertures therein in registry with ~-the conductive pattern, scoring the laminations between con-ductive patterns, firing the laminate to produce a cured ceramic containing a multiplicity of capacitors, attaching leads to the capacitor electrodes through the apertures, and thereafter breaking individual capacitors from the sheet at the score lines.
An object of this invention is to provide a new and improved method of making single layer capacitors in multiple.
Another object of this invention is to provide a ~ ~ -method of making single layer capacitors in multiple which per-mits such capacitors to be made in greatly increased capacitance values for a given size.
A further object of this invention is to provide a method of making single layer capacitors in multiple which facilitates the handling of the capacitive elements.
A still further object of this invention is to pro-vide a new and improved ceramic capacitor of increased capaci-tance value for a given electrode area.
In one aspect of the present invention there is pro-vided a method of making capacitors in multiple which com-prises providing a first thin flat sheet of ceramic greenware, ~`
defining a multiplicity of conductive patterns on either side thereof in alignment to form a multiplicity of opposed indivi-dual capacitors, prouiding second and third sheets of ceramic greenware, laminating said second and third sheets to either side of said first sheet, thereafter scoring said lamination to define individual capacitors between but not extending to said score marks, firing said lamination to produce a cured ceramic assembly of multiplicity of single layer capacitors, 1~5Z21 and thereafter breaking capacitors from said assembly along ~ ~
the score marks. `~ .
In a further aspect of the present invention there is provided a method of making capacitors in multiple which comprises providing a thin flat first sheet of ceramic green-ware, defining a multiplicity of conductive patterns on either :.
side thereof in alignment to form a multiplicity of opposed individual capacitors, providing second and third sheets of ceramic greenware sheets with apertures therein and laminating L0 said second and third sheets to ei~her side of said firstsheet with the apertures in registry with said patterns, scor-ing said lamination to define individual capacitors between but not extending to said score marks, firing said lamination to produce a cured ceramic assembly of a multiplicity of capacitors, .
and thereafter breaking capacitors from said assembly along said score marks.
The features of the invention which are believed to be novel are particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, 20 however, both as to its organization and operation, together :
with further objects and advantages thereof, may best be appre- ~;
ciated by reference to the following detailed description taken in conjunction with the drawings, wherein:
.~ , ,. ~ . -. .. :
- . ~
' ~`' ~ ' ',' , : ' .
- 1~4SZZl FIG. 1 is a view in perspective of a multiple capacitor construction embodying the invention;
FIG. 2 is a top view of a rnultiple capacltor construction made in accordance with the invention;
FIG. 3 is a longitudinal sectional view seen in the plane of lines 3-3 of Fig. 2, with leads attached;
FIG. 4 is a vlew of a SinglQ capacitor made ln accordance wlth the lnvention;
FIG. 5 ls a view similar to Fig. 1 showing another method of practiclng the invention;
FIG. 6 is a sectlonal vlQw of a capacitor made in accordance with the structure of Fig. 5;
FIG. 7 ls a view in perspectlve of another multi-capacitor structure made in accordance wlth the invention;
FIGS. 8 and 9 are views of opposite sides of one of the elements of Flg. 7 showing capacitor electrodes defined thereon; and FIG. 10 is a longi~ud~nal sectlonal vlew of a ;-single capacitor made ln accordance with the embodiment of Figs. 7 - 9.
Flgs. 1 - 3 exempllfy an assembly 10 of single layer capacitors in multiple and comprises first and second strips 11 and 12 of ceramlc greenware in strip form. Strlps 11 and 12 have a plurality of pQrforatlons 13 and 14, respectively, deflned therein in a coordinate arrangement.
A central strlp of ceramlc greenware 15 has a plurallty of conductive areas 16 on one side and a llke plurallty Or conductlve areas 17 on the other slde. The opposite areas or patterns 16 and 17 are parallel and ln vertlcal .. I
1~45ZZl alignment when the strips are horizontally disposed.
The strips 11, 15 and 12 are laminated together under heat and pressure, then scored as shown in Figs. 2 and 3 along coordinate lines 18 and 19 to provide breaking or snapping lines.
The laminated and scored assembly is then fired at a high temp-erature to fuse the ceramic. Thereafter, connector leads 20 and 21 preferably of the nailhead type are positioned in perfora-tions 13 and 14, respectively, and bonded to patterns 16 and 17.
Then rows of capacitors may be snapped or broken from the assembly at the score lines 18 and individual capacitors at the score lines 19, or vice versa.
In the practice of the invention, the strips 11, 12 and 15 are slip cast to the desired thickness from a mixture com-prising ceramic particles, plasticizer binder and solvent. In one example, the ceramic may be lead barium niobate (PBN) mixed with liquid methyl methacrylate and Monsanto Chemical Company #160 Santicizer* (a plasticizer) and an ethylene dichloride sol-vent. The resulting mixture is slip cast to the desired thick-ness, dried, and cut into strips of predetermined size. The mix-ture may be ceramic 40-70%, binder 20-50%, plasticizer 1-4%, and solvent 10-20%. The mixture is blended and then cast. After a period of air drying, the resultant strip or tape may be dried at elevated temperatures of 200 - 400F to completely drive out sol-vents, water, etc. The strips 11 and 12 are then perforated in the illustrated coordinate pattern. The strips 15 are coated with the conductive patterns 16 and 17 on each side thereof. The three strips are then laminated to a homogeneous assembly.
The conductive patterns are defined on strips 15 in any suitable manner. One technique is to utilize a screening pro-cess wherein conductive material in a liquid vehicle is screened or squeezed through a screening pattern. A suitable substance for this process is Quick Film Conductor Ink #MBl-l69 * - Trade mark .~ .
..... ,,, ~ ' ( ~04SZ21 of ~latthey Blshop, ~nc., Melvern, Pennsylvania which contains a gold, palladium and platinum in a thick liquid binder.
The binder burns off when the ceramic ls flred leaving a metallized conductor.
Where the strip 15 is extremely thin, and therefore not easily handled, the patterns 16 may be placed on a release surface, the strip 15 laid or cast on patterns 16 and on the release surface; patterns 17 are then screened on the ,~
upper surface. One of strips 11 or 12 is placed on strlp 15 over patterns 17. The strips are then peeled upwardly taking patterns 16 from the release surface, and then the ¦
other of sbrips 11 or 12 is applied to strip 15 over patterns 16. The assembly is then laminated, scored and fired. The strips may be laminatsd at a pressure of 2000 psi and a temperature of 120F.
In this technique the release surface may be substantially transparent or translucent, and the greenware strip due to its small thlckness is also translucent. A source of light may be placed behind the release surface to illuminate the patterns through the greenware strip., Firing of the above-described assembly may be accompllshed in a through oven with an entrance-exit time of six hours, where the assembly is exposed to a top temperature of 2300F
for approximately one hour. Ths time and temperature may vary in accordance,with various types of ceramic which may be used.
Upon flrlng or sintering the organic constituents of the green ceramic strips or sheets volatize and the csramic becomes a monolithic structure.
For physlcal strength of the fired ceramic, it ls preferred that the overall thickness be at least 0.002".
The strlps 11 and 12 are therefore on the order of O.OOl' or'greater while the strip 15 may be only 0.0005" thick.
Inasmuch as the capacitance value of each unit is proportional to the spacing betwQen the conductors 16 and 17, 5.
~ ~45Z21 as well as the ar~a of the patterns, the m~n~mal thickness of the strip provides individual capacitors of greatly increased capacitance valu~.
In one product, conductors 0.103" on sides are defined in eight columns of t~enty-three on a strip 15, one and one-quar~er inch by four and one-half inches and 0.001" thick. The perfora~ions are made .050" to accept connectors having 0.045" heads. This product with a strip 15 which is 0.001" thick yields capacitors of over 3800 picofa~ads.-The connectors may be formed ~or predoterminQd spaclngof the leads. Fig. 4 illustrates an individual capacitor 22 having connectors 20a and 21a preformed to provlde a predetermining dimension therebetween. The connectors are applied in multiple, being held in a fixture, inserted into the perforations, and heated in an oven to solder the heads thereof to the conductors. The solder may be initially deposited in the perforations, or the connector heads dipped into a solder bath prior to insertion into the perforations.
After the indivldual capacitors are separated they may be encapsulated and color coded if desired. However, this is not necessary.
In an alternate technlque, the center strip 15 may be defined by two strips positioned back-to-back with the conductive patterns defined on the outer surfaces. This - permits the center strips to have the patterns defined on only one side and thus decrease the physical handling of one thin strip.
The edges of the conductive patterns are spaced from the score llnes which define the physical edges of the individual capacitors. This provides an increased 6.
.
, ~ ~
~45ZZl path for any leakage wlth respect to capacitors where the conductor extends to the physical edge of the capacltor.
Where the conductive patterns are initially applied to a release surface such as release paper, plastic tape, etc., the patterns may be printed by varlous presses and techniques. The greenware may be applied over the release surface by slip casting, or any other suitable technique.
FIGS. 5 and 6 exemplify another embodiment of the lnvention. In thls embodiment outer strips 25 and 26 are ;
formed wlth coordinate rows and columns of perforations 27 and 28, respectively. Conductive patterns 29 and 30 are then defined in coordinate rows and columns on the faclng surfaces of the s~rips 25 and 26, respectively.
An intermediate strip 32 has coordinate rows and columns of small clrcles or dots of conductive material 31 defined thereon. The dots, which are preferably circular, but need not be, are of an area larger than the perforations 27 and 28 and are ln registry with such perforations so as to complete the conductive surface interrupted by the perforations 27 and 28.
In assembly, the strips 25, 26 and 32 are placed together ln allgnment laminated under pressure and heat as previously described, and a cross-section of the resulting product will appear as shown in Fig. 6. Fig. 6, however, for purposes of illustration exaggerates the th~ckness of the conductive patterns and particularly the dots 31, inas-much as the dots 31 will blend or merge into the patterns 29 and 30. The resulting assem~ly is scored as previously described and indicated by the score mark 33. Thereafter, the ceramic is fired, leads are applied to the areas of the perforations as prevlously described.
'' , 1045ZZl The lnventlon may also be embodied in the makin~ of sinæle layer capacitors of the so-called chip type in multiple, as shown in Figs. 7 - 10. Plain strips of greenware 40 and 41 are arranged to receive therebetween a strip 42 having opposi~e sides 43 and 44 as more clearly shown in Figs. 8 and 9. Printed or ctherwise deflned on the sides 43 and 44 are coordinate rows and columns of conductive patterns 45 and 46, respectively, whlch are prlnted in registry on either side and each pattern 45 and 46 has a tab-like extension 47 and 48, respectively, extending in opposite directions to provide leads for terminals.
After assembly of the strips 40, 41 and 42, they are coordinately scored as indicated by the lines 49 and 50 and fired. Thereafter, a strlp defined by a score mark 49 may be snapped from the assembly, the ends metallized to provide external electrical connections to the tabs 47 and 48 and lndividual capacitors may be snapped from each row. This provides the so-called chip-type capacitor wherein the metallized ends 51 and 52 areelectrically connected to tabs 47 and 48, respectively, and are adapted to be placed on or in an electrlcal circuit. A cross-sectlon of such a capacitor ls shown in Fig. 10 with metallized opposed edges 51 and 52.
After the assembly of strips and lamination thereof, the score marks may be deflned ln any suitable manner.
This may be done by a knife-edge wherein the assembled greenware is moved beneath a plurality of knives in coordinate directions. A die may be used, a rectangular grid~ preferably heated, may be used to lndent the score marks or a laser beam may be utili~d for the scoring.
Dependent upon the depth and wldth of the scoring, a score depth of six to twenty-five percent of the overall thickness will be sufficient. Then a forcs in the range of eight to twenty-fivQ thousand ps~ will be all that is required to snap off a row of capacitors.
While thls pressure in pounds per squa~e inch may seem to be high, it will be apparent that the area involved is extremely small.
In some instances, lt may be desirable not to score the gresnware assembly prlor to c~ng. In this situation, scoring may be accomplished througn use Or a laser beam.
The inventlon rurther permits the use of a plurality of single layer capacitors in onQ body, so that a slngle capacitor structure including a plurality of distinct capacitors may be connected in a circult. Either a column or row, or even two or three capacitors, may be left in an lntegral strip, and the capacitors connected individually in a circuit. Alt~rnaf-lv~ty,some capacitors may be connected individually, while others would have their leads connected in parallel for increased capacltance.
From the foregoing disclosure it may be seen that the objects of the invention ar~ efficiently attained. While preferred embodiments of the invention have been set forth for purposes of disclosure, it is to be understood that other embodlments to the invention as well as modifications to the disclosed embodiment which do not depart from the spirit and scope of the invention may become apparent to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments and modifications of the invention which do not depart from the spirit and scope o~ the invention.
.
. , . . :
--.
This inventlon relatos to capacitors and mors partl-cularly relates to ceramic capacitors having a higher capacltance valu2, and a method of making the same.
The present invention is directed to capacitors which are of the single layer type, that is, include only two electrodes with a dlelectric spacing therebetween, where such capacitors are manufactured in multiple. At the present time, capacltors of the typo to which this invention relate3 are made with a flred ceramic dielectric which, after curing, - ls coated wlth a conductive substance on each side thereof.
The dlelectrlc ls then cut into indlvidual capacitors, leads applied, and the ceramic with conductive coating~
thereon encapsulated in an insulating material.
The production of this single layer type capacitor -by present methods results in a capacltor of limited capacitan~e value pr~marlly due to the thickness of the ceramlc dlelectrlc. The dlelectric must be made sufficiently thlck to have the required physical strength for handling both in a greenware state and in the fired state, and also whlch ls sufflclently thick so tha~ it will not unduly warp when the ceramlc greenware is fired.
The present lnventlon provides a new and improved method of manufacturlng single layer capacitors which enables the use of very thin ceramic spacers between the capacltor electrodes and permits a plurality of capacitors to be defined on a strlp of ceramlc greenware ln such a manner a~ to decrease the possibility of leakage between the capacitor electrodes.
Brlefly stated, the invention in one form thereof comprises the steps of defining a plurality of conductive _1, . ., 1C)45Z'~
patterns on opposite sides of a thin sheet of ceramic green-ware, covering said thin sheet on either side with other sheets of ceramic greenware having apertures therein in registry with ~-the conductive pattern, scoring the laminations between con-ductive patterns, firing the laminate to produce a cured ceramic containing a multiplicity of capacitors, attaching leads to the capacitor electrodes through the apertures, and thereafter breaking individual capacitors from the sheet at the score lines.
An object of this invention is to provide a new and improved method of making single layer capacitors in multiple.
Another object of this invention is to provide a ~ ~ -method of making single layer capacitors in multiple which per-mits such capacitors to be made in greatly increased capacitance values for a given size.
A further object of this invention is to provide a method of making single layer capacitors in multiple which facilitates the handling of the capacitive elements.
A still further object of this invention is to pro-vide a new and improved ceramic capacitor of increased capaci-tance value for a given electrode area.
In one aspect of the present invention there is pro-vided a method of making capacitors in multiple which com-prises providing a first thin flat sheet of ceramic greenware, ~`
defining a multiplicity of conductive patterns on either side thereof in alignment to form a multiplicity of opposed indivi-dual capacitors, prouiding second and third sheets of ceramic greenware, laminating said second and third sheets to either side of said first sheet, thereafter scoring said lamination to define individual capacitors between but not extending to said score marks, firing said lamination to produce a cured ceramic assembly of multiplicity of single layer capacitors, 1~5Z21 and thereafter breaking capacitors from said assembly along ~ ~
the score marks. `~ .
In a further aspect of the present invention there is provided a method of making capacitors in multiple which comprises providing a thin flat first sheet of ceramic green-ware, defining a multiplicity of conductive patterns on either :.
side thereof in alignment to form a multiplicity of opposed individual capacitors, providing second and third sheets of ceramic greenware sheets with apertures therein and laminating L0 said second and third sheets to ei~her side of said firstsheet with the apertures in registry with said patterns, scor-ing said lamination to define individual capacitors between but not extending to said score marks, firing said lamination to produce a cured ceramic assembly of a multiplicity of capacitors, .
and thereafter breaking capacitors from said assembly along said score marks.
The features of the invention which are believed to be novel are particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, 20 however, both as to its organization and operation, together :
with further objects and advantages thereof, may best be appre- ~;
ciated by reference to the following detailed description taken in conjunction with the drawings, wherein:
.~ , ,. ~ . -. .. :
- . ~
' ~`' ~ ' ',' , : ' .
- 1~4SZZl FIG. 1 is a view in perspective of a multiple capacitor construction embodying the invention;
FIG. 2 is a top view of a rnultiple capacltor construction made in accordance with the invention;
FIG. 3 is a longitudinal sectional view seen in the plane of lines 3-3 of Fig. 2, with leads attached;
FIG. 4 is a vlew of a SinglQ capacitor made ln accordance wlth the lnvention;
FIG. 5 ls a view similar to Fig. 1 showing another method of practiclng the invention;
FIG. 6 is a sectlonal vlQw of a capacitor made in accordance with the structure of Fig. 5;
FIG. 7 ls a view in perspectlve of another multi-capacitor structure made in accordance wlth the invention;
FIGS. 8 and 9 are views of opposite sides of one of the elements of Flg. 7 showing capacitor electrodes defined thereon; and FIG. 10 is a longi~ud~nal sectlonal vlew of a ;-single capacitor made ln accordance with the embodiment of Figs. 7 - 9.
Flgs. 1 - 3 exempllfy an assembly 10 of single layer capacitors in multiple and comprises first and second strips 11 and 12 of ceramlc greenware in strip form. Strlps 11 and 12 have a plurality of pQrforatlons 13 and 14, respectively, deflned therein in a coordinate arrangement.
A central strlp of ceramlc greenware 15 has a plurallty of conductive areas 16 on one side and a llke plurallty Or conductlve areas 17 on the other slde. The opposite areas or patterns 16 and 17 are parallel and ln vertlcal .. I
1~45ZZl alignment when the strips are horizontally disposed.
The strips 11, 15 and 12 are laminated together under heat and pressure, then scored as shown in Figs. 2 and 3 along coordinate lines 18 and 19 to provide breaking or snapping lines.
The laminated and scored assembly is then fired at a high temp-erature to fuse the ceramic. Thereafter, connector leads 20 and 21 preferably of the nailhead type are positioned in perfora-tions 13 and 14, respectively, and bonded to patterns 16 and 17.
Then rows of capacitors may be snapped or broken from the assembly at the score lines 18 and individual capacitors at the score lines 19, or vice versa.
In the practice of the invention, the strips 11, 12 and 15 are slip cast to the desired thickness from a mixture com-prising ceramic particles, plasticizer binder and solvent. In one example, the ceramic may be lead barium niobate (PBN) mixed with liquid methyl methacrylate and Monsanto Chemical Company #160 Santicizer* (a plasticizer) and an ethylene dichloride sol-vent. The resulting mixture is slip cast to the desired thick-ness, dried, and cut into strips of predetermined size. The mix-ture may be ceramic 40-70%, binder 20-50%, plasticizer 1-4%, and solvent 10-20%. The mixture is blended and then cast. After a period of air drying, the resultant strip or tape may be dried at elevated temperatures of 200 - 400F to completely drive out sol-vents, water, etc. The strips 11 and 12 are then perforated in the illustrated coordinate pattern. The strips 15 are coated with the conductive patterns 16 and 17 on each side thereof. The three strips are then laminated to a homogeneous assembly.
The conductive patterns are defined on strips 15 in any suitable manner. One technique is to utilize a screening pro-cess wherein conductive material in a liquid vehicle is screened or squeezed through a screening pattern. A suitable substance for this process is Quick Film Conductor Ink #MBl-l69 * - Trade mark .~ .
..... ,,, ~ ' ( ~04SZ21 of ~latthey Blshop, ~nc., Melvern, Pennsylvania which contains a gold, palladium and platinum in a thick liquid binder.
The binder burns off when the ceramic ls flred leaving a metallized conductor.
Where the strip 15 is extremely thin, and therefore not easily handled, the patterns 16 may be placed on a release surface, the strip 15 laid or cast on patterns 16 and on the release surface; patterns 17 are then screened on the ,~
upper surface. One of strips 11 or 12 is placed on strlp 15 over patterns 17. The strips are then peeled upwardly taking patterns 16 from the release surface, and then the ¦
other of sbrips 11 or 12 is applied to strip 15 over patterns 16. The assembly is then laminated, scored and fired. The strips may be laminatsd at a pressure of 2000 psi and a temperature of 120F.
In this technique the release surface may be substantially transparent or translucent, and the greenware strip due to its small thlckness is also translucent. A source of light may be placed behind the release surface to illuminate the patterns through the greenware strip., Firing of the above-described assembly may be accompllshed in a through oven with an entrance-exit time of six hours, where the assembly is exposed to a top temperature of 2300F
for approximately one hour. Ths time and temperature may vary in accordance,with various types of ceramic which may be used.
Upon flrlng or sintering the organic constituents of the green ceramic strips or sheets volatize and the csramic becomes a monolithic structure.
For physlcal strength of the fired ceramic, it ls preferred that the overall thickness be at least 0.002".
The strlps 11 and 12 are therefore on the order of O.OOl' or'greater while the strip 15 may be only 0.0005" thick.
Inasmuch as the capacitance value of each unit is proportional to the spacing betwQen the conductors 16 and 17, 5.
~ ~45Z21 as well as the ar~a of the patterns, the m~n~mal thickness of the strip provides individual capacitors of greatly increased capacitance valu~.
In one product, conductors 0.103" on sides are defined in eight columns of t~enty-three on a strip 15, one and one-quar~er inch by four and one-half inches and 0.001" thick. The perfora~ions are made .050" to accept connectors having 0.045" heads. This product with a strip 15 which is 0.001" thick yields capacitors of over 3800 picofa~ads.-The connectors may be formed ~or predoterminQd spaclngof the leads. Fig. 4 illustrates an individual capacitor 22 having connectors 20a and 21a preformed to provlde a predetermining dimension therebetween. The connectors are applied in multiple, being held in a fixture, inserted into the perforations, and heated in an oven to solder the heads thereof to the conductors. The solder may be initially deposited in the perforations, or the connector heads dipped into a solder bath prior to insertion into the perforations.
After the indivldual capacitors are separated they may be encapsulated and color coded if desired. However, this is not necessary.
In an alternate technlque, the center strip 15 may be defined by two strips positioned back-to-back with the conductive patterns defined on the outer surfaces. This - permits the center strips to have the patterns defined on only one side and thus decrease the physical handling of one thin strip.
The edges of the conductive patterns are spaced from the score llnes which define the physical edges of the individual capacitors. This provides an increased 6.
.
, ~ ~
~45ZZl path for any leakage wlth respect to capacitors where the conductor extends to the physical edge of the capacltor.
Where the conductive patterns are initially applied to a release surface such as release paper, plastic tape, etc., the patterns may be printed by varlous presses and techniques. The greenware may be applied over the release surface by slip casting, or any other suitable technique.
FIGS. 5 and 6 exemplify another embodiment of the lnvention. In thls embodiment outer strips 25 and 26 are ;
formed wlth coordinate rows and columns of perforations 27 and 28, respectively. Conductive patterns 29 and 30 are then defined in coordinate rows and columns on the faclng surfaces of the s~rips 25 and 26, respectively.
An intermediate strip 32 has coordinate rows and columns of small clrcles or dots of conductive material 31 defined thereon. The dots, which are preferably circular, but need not be, are of an area larger than the perforations 27 and 28 and are ln registry with such perforations so as to complete the conductive surface interrupted by the perforations 27 and 28.
In assembly, the strips 25, 26 and 32 are placed together ln allgnment laminated under pressure and heat as previously described, and a cross-section of the resulting product will appear as shown in Fig. 6. Fig. 6, however, for purposes of illustration exaggerates the th~ckness of the conductive patterns and particularly the dots 31, inas-much as the dots 31 will blend or merge into the patterns 29 and 30. The resulting assem~ly is scored as previously described and indicated by the score mark 33. Thereafter, the ceramic is fired, leads are applied to the areas of the perforations as prevlously described.
'' , 1045ZZl The lnventlon may also be embodied in the makin~ of sinæle layer capacitors of the so-called chip type in multiple, as shown in Figs. 7 - 10. Plain strips of greenware 40 and 41 are arranged to receive therebetween a strip 42 having opposi~e sides 43 and 44 as more clearly shown in Figs. 8 and 9. Printed or ctherwise deflned on the sides 43 and 44 are coordinate rows and columns of conductive patterns 45 and 46, respectively, whlch are prlnted in registry on either side and each pattern 45 and 46 has a tab-like extension 47 and 48, respectively, extending in opposite directions to provide leads for terminals.
After assembly of the strips 40, 41 and 42, they are coordinately scored as indicated by the lines 49 and 50 and fired. Thereafter, a strlp defined by a score mark 49 may be snapped from the assembly, the ends metallized to provide external electrical connections to the tabs 47 and 48 and lndividual capacitors may be snapped from each row. This provides the so-called chip-type capacitor wherein the metallized ends 51 and 52 areelectrically connected to tabs 47 and 48, respectively, and are adapted to be placed on or in an electrlcal circuit. A cross-sectlon of such a capacitor ls shown in Fig. 10 with metallized opposed edges 51 and 52.
After the assembly of strips and lamination thereof, the score marks may be deflned ln any suitable manner.
This may be done by a knife-edge wherein the assembled greenware is moved beneath a plurality of knives in coordinate directions. A die may be used, a rectangular grid~ preferably heated, may be used to lndent the score marks or a laser beam may be utili~d for the scoring.
Dependent upon the depth and wldth of the scoring, a score depth of six to twenty-five percent of the overall thickness will be sufficient. Then a forcs in the range of eight to twenty-fivQ thousand ps~ will be all that is required to snap off a row of capacitors.
While thls pressure in pounds per squa~e inch may seem to be high, it will be apparent that the area involved is extremely small.
In some instances, lt may be desirable not to score the gresnware assembly prlor to c~ng. In this situation, scoring may be accomplished througn use Or a laser beam.
The inventlon rurther permits the use of a plurality of single layer capacitors in onQ body, so that a slngle capacitor structure including a plurality of distinct capacitors may be connected in a circult. Either a column or row, or even two or three capacitors, may be left in an lntegral strip, and the capacitors connected individually in a circuit. Alt~rnaf-lv~ty,some capacitors may be connected individually, while others would have their leads connected in parallel for increased capacltance.
From the foregoing disclosure it may be seen that the objects of the invention ar~ efficiently attained. While preferred embodiments of the invention have been set forth for purposes of disclosure, it is to be understood that other embodlments to the invention as well as modifications to the disclosed embodiment which do not depart from the spirit and scope of the invention may become apparent to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments and modifications of the invention which do not depart from the spirit and scope o~ the invention.
.
. , . . :
--.
Claims (14)
1. A method of making capacitors in multiple which com-prises providing a first thin flat sheet of ceramic greenware, defining a multiplicity of conductive patterns on either side thereof in alignment to form a multiplicity of opposed indiv-idual capacitors, providing second and third sheets of ceramic greenware, laminating said second and third sheets to either side of said first sheet, thereafter scoring said lamination to define individual capacitors between but not extending to said score marks, firing said lamination to produce a cured ceramic assembly of a multiplicity of single layer capacitors, and thereafter breaking capacitors from said assembly along the score marks.
2. The method of claim 1 wherein said patterns are defined with extending connection leads, said connection leads extend-ing in opposite directions on opposite sides of said first sheet, said scores being made at the ends of said connection leads.
3. The method of claim 1 wherein said second and third sheets each have a multiplicity of apertures therein to pro-vide communication therethrough to said patterns and the method includes the further step of connecting leads to said patterns through said apertures.
4. The method of claim 1 wherein the patterns are defined on at least one side of said first sheet by initially defining the patterns on a release surface, then superimposing said first sheet on said release surface and removing said first sheet from said release surface with the patterns thereon.
5. The method of claim 4 wherein patterns are defined on the other side of said first sheet before said first sheet is removed from said release surface.
6. The method of claim 4 wherein said release surface and said first sheet are translucent and including the further step of providing illumination behind said release surface.
7. The method of claim 5 wherein said release surface and said first sheet are translucent and including the further step of providing illumination behind said release surface.
8. The method of claim 1 wherein said first sheet is formed by defining said patterns on two separate sheets and laminating the non-pattern sides of said two separate sheets together.
9. A method of making capacitors in multiple which comprises providing a thin flat first sheet of ceramic green-ware, defining a multiplicity of conductive patterns on either side thereof in alignment to form a multiplicity of opposed individual capacitors, providing second and third sheets of ceramic greenware sheets with apertures therein and laminating said second and third sheets to either side of said first sheet with the apertures in registry with said patterns, scor-ing said lamination to define individual capacitors between but not extending to said score marks, firing said lamination to produce a cured ceramic assembly of a multiplicity of capacitors, and thereafter breaking capacitors from said assembly along said score marks.
10. The method of claim 9 including the further step of connecting leads to said patterns through said apertures.
11. The method of claim 9 wherein said first sheet is formed by defining said patterns on two separate sheets and laminating the non-pattern sides of said two separate sheets together.
12. A method of making capacitors in miltiple comprising the steps of providing first and second sheets of ceramic greenware having a pattern of apertures therein, defining first conductive patterns on one side of each of said sheets encom-passing said apertures, providing a third sheet of ceramic greenware, defining second conductive areas on both sides thereof of greater areas than said apertures, laminating said sheets together with said third sheet intermediate said first and second sheets with the conductive areas of said third sheet spanning said apertures, scoring said lamination, firing said lamination, attaching leads to each of said patterns through said apertures, and separating said capacitors from each other after firing along said scores.
13. The method of claim 12 wherein said lamination is scored between said individual capacitors before firing and individual capacitors are broken from the assembly along the scores after firing.
14. A method of making capacitors in multiple which com-prises providing a thin flat first sheet of ceramic greenware, defining a multiplicity of conductive patterns on either side thereof in alignment to form a multiplicity of opposed individual capacitors, providing second and third sheets of ceramic green-ware sheets with apertures therein and laminating said second and third sheets to either side of said first sheet with the apertures in registry with said patterns, firing said lamination to produce a cured ceramic assembly of a multiplicity of capacitors, and separating individual capacitors from said lamin-ation along lines between but not extending to said patterns.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA225,854A CA1045221A (en) | 1975-04-28 | 1975-04-28 | Method of making ceramic capacitor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA225,854A CA1045221A (en) | 1975-04-28 | 1975-04-28 | Method of making ceramic capacitor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1045221A true CA1045221A (en) | 1978-12-26 |
Family
ID=4102952
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA225,854A Expired CA1045221A (en) | 1975-04-28 | 1975-04-28 | Method of making ceramic capacitor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1045221A (en) |
-
1975
- 1975-04-28 CA CA225,854A patent/CA1045221A/en not_active Expired
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