CA1167247A - Conductor inks - Google Patents
Conductor inksInfo
- Publication number
- CA1167247A CA1167247A CA000388159A CA388159A CA1167247A CA 1167247 A CA1167247 A CA 1167247A CA 000388159 A CA000388159 A CA 000388159A CA 388159 A CA388159 A CA 388159A CA 1167247 A CA1167247 A CA 1167247A
- Authority
- CA
- Canada
- Prior art keywords
- percent
- weight
- glass frit
- bismuth oxide
- copper powder
- 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
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/09—Use of materials for the conductive, e.g. metallic pattern
- H05K1/092—Dispersed materials, e.g. conductive pastes or inks
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
- C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
- C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
- C03C8/18—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions containing free metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
- C22C32/0089—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with other, not previously mentioned inorganic compounds as the main non-metallic constituent, e.g. sulfides, glass
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Inorganic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Dispersion Chemistry (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Parts Printed On Printed Circuit Boards (AREA)
- Inks, Pencil-Leads, Or Crayons (AREA)
- Conductive Materials (AREA)
- Paints Or Removers (AREA)
Abstract
RCA 75,431 IMPROVED CONDUCTOR INKS
ABSTRACT OF THE DISCLOSURE
Improved conductor inks useful in constructing multilayer circuits, particularly on porcelain coated metal substrates, are provided. The subject inks comprise: copper powder, a barium calcium borosilicate glass frit, a suitable organic vehicle and bismuth oxide, which is present either in admixture with the copper powder or as a component of the glass frit.
ABSTRACT OF THE DISCLOSURE
Improved conductor inks useful in constructing multilayer circuits, particularly on porcelain coated metal substrates, are provided. The subject inks comprise: copper powder, a barium calcium borosilicate glass frit, a suitable organic vehicle and bismuth oxide, which is present either in admixture with the copper powder or as a component of the glass frit.
Description
-1 RCA 75, 431 CONDUCTOR INKS
This invention relates to thick-film conductor inks and their use in multilayer electrical circuit structures on porcelain-coated metal boards.
BACKGROUND_OF T~E INVENTION
The use of specialized ink formulations to form thick films having various functions on suitable substrates in the construction of multilayer structures is well known in the art. Such technology is of increasing interest in the fabrication of very dense multilayer integrated clrcuit patterns on various substrates for a wide variety of applications in the electronics industry.
Significantly improved substrates for the fabrication of such circuits are disclosed and claimed in Hang et al., U.S. Patent No. 4,256,796, issued March 17, 1981. The Hang et al. substrates are metal coated with an improved porc01ain composition comprised of a mixture, based on its oxide content, of magnesium oxide (MgO~ or mixtures of magnesium oxide and certain other oxides, barium oxide (BaO), boron trioxide (B2O3~ and silicon dioxide (SiO2).
While the porcelain-coated metal substrates of Hang et al. represent a significant improvement over previously known substrate materials, they are disadvantageous only in being incompatible or poorly compatible with commercially a~ailable thick-film inks.
; This invention is concerned with improved coppe~ conductor inks compatible with the Hang et al. substrates.
It is generally recognized that it is advantageous to include bismuth oxide in copper conductor inks to improve the solderability of films formed therefrom. Conventionally, such inks contain from about 5 percent up to as much as 10 percent by weight bismuth oxide. We have found that bismuth oxide in amounts in excess of about 3 percent by weight of the ink formulation will frequently cause a reaction at the point of contact between a conductor film and a resistor. This results in ~, 672~ 7 l -2- RCA 75,431 a signiEicantly increased resistance at the point of contact, a distinct disadvantage.
In accordance with this invention, copper conductor inks are provided which are compatible with the Hang et al. substrates, and are characterized by good solderability without the aforementioned point of contact reaction with resistors.
SUMMARY OF THE INVENTION
The improved conductor inks of this inven-tion comprise a barium calcium borosilicate glass, copper powder, bismuth trioxide and a suitable organic vehicle.
DETAILED DESCRIPTION OF T~E INVENTION
In accordance with -this invention, there are provided improved copper conductor inks of high reliability useful in the production of complex single or multilayer thick-film circuits on suitable substrates, particularly the porcelain-coated metal circuit boards of Hang et al.
In addition -to being compatible with the porcelain of the Hang et al. substrates, the improved copper conductor inks of this invention are compatible with inks of other functions specifically formulated therefor. The subject copper conductor inks and other functional and pro-tec-tive inks formulated for the ~ang et al. porcelain-coated metal boards, together with the ~boards themselves, represent a significant advance in multiIayer thick-film integrated circuit structures.
~ The novel copper conductor inks of this 30 ~ invention are comprised of copper powder, a glass frit, bismuth oxide and a suitable organic vehicle.
The gIass frit of the cond-uctor inks of this invention is a barium calcium borosilicate glass which is compatible wi~h the porcelain of the Hang et al. boards.
3~ As a result, thich-film conductors prepared from the subject in~s have excellent reheat stability and thermal expansion properties similar to the Hang et al. substrate boards. In addition, by controlling the amount of bismuth oxide included in the inks of this invention, conductor ", ~
. ,~,. .. .. .
..
.
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I -3- RCA 75,431 thick-films formed from the inks of this inven-tion are not characterized by the aforementioned reaction at point of contact with resistors, yet possess the solderability conventionally associated with larger amounts of bismuth oxide.
The glass frit of the novel inks of this invention is a barium calcium borosilicate glass consisting of, on a weight basis:
a) from about 40 to about 55 percent, preferably about 52 percent, of barium oxide;
b) from about lO to about 15 percent, preferably about 12 percent, of calcium oxide;
c) from about 14 to about 25 percent, preferably about 16 percent, of boron trioxide; and d~ from about 13 to about 23 percent, preferably about 20 percent, of silicon dioxide. The glass frit comprises from about 1 to about 15 percent, preferably from about 2 to about 6 percent by weight, of the total ink cOmpOsition.
The copper powder utilized in the conductive inks of this invention is pure copper having a particle size of about 3.0 to 3.2 micrometers. The copper comprises from abou-t 70 to about 40 percent, preferably from about 7~ to about 82 percent by weight, of the subject ink compositions.
The conductor inks of this invention contain from about 0.5 to about 3.0 percent, preferably from about 1 to about 2 percent by weight, of bismuth oxide. It is critical that the bismuth oxide content does not exceed about 3 percent by weight of the total ink composition.
It i~s also necessary that the subjec-t inks contain no lead ; oxide since its presence will cause the same termination reactions, even where the bismuth oxide content is well below the 3 weight percent maximum. The bismuth oxide and the glass frit are preferably present in the subjec-t inks in a weight ratio of from about 1:1 to abou-t 1:3. The bismuth oxide may be added to the subject inks as a powder or may be present in the-glass frit itself.
''' ~'`'` ~' . ` ' `' ' '' ' i7~47 I -4- RCA 75,431 The oryanic vehicles are blnders such as, for example, cellulose derivatives, particularly ethyl cellulose, synthetic resins such as polyacrylates or methacrylates, polyesters, polyolefins and the like. In general, conventional vehicles utilized in inks of the type described herein may be used in the subject inks.
Preferred commercially available vehicles include, for e~ample, pure liquid polybutenes available as Amoco H-25 Amoco H-50~and Amoco I.-100 from Amoco Chemicals Corporation, poly n-butylmethacrylate available from E. I.
duPont de Nemours and Co., and the like.
The above resins may be utilized individually or in any combination of -two or more. A suitable viscosity modifier can be added to the resin material if desired.
These modifiers can be sol~ents such as those conventionally used in similar ink compositions, e.g. pine oil, terpineol, butyl carbitol acetate, an ester alcohol available from Texas Eastman Company under the trademark Texanol and the like, or solid materials such as, for example, a castor oil derivative available from N.L.
Industries under the trademark Thixatrol.
The vehicle of the subject inks may also contain ; up to about 25 percent by weight, preferably from about 10 to about 20 percent by weight, based on the vehicle, of a suitable wetting agent of the type conventionally used in copper conductor inks to aid in coating the particles of ~copper powder with the organic vehicle. As is the case with all components of the organic vehicle,the wetting 0 agent must fire cleanly in nitrogen, i.e., without leaving a carbonaceous residue.~ A preferred wet-ting agent is a dispersion of a complex multifunctional, aliphatic hydrocarbon in an aliphatic hydrocarbon oil available under the trademark Hypothiolate 100 from Central Compounding Company, Chicago, Illinois. The organic vehicle comprises from about ~to about 25 percent by weight, preferably from about 12 to about 15 percent by weight,~of the subject inks.
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I -5- RCA 75,431 The improved copper conductor inks of this invention are applied to the substrate, e.g., conventional alumina boards or the improved porcelain-coated metal boards of Hang et al. by conventional means, i.e. screen printing, brushing, spraying and the like, with screen printing being preferred. The coating of ink is then dried in air at 100 - 125C for about 15 minutes. The resulting film is then fired in nitrogen at peak 10 -temperatures of from 850 to 950C. for from 4 to 10 minutes.
Films formed from the novel conductor inks of this invention have been demonstrated to be comparable with conventional copper conductor inks in all properties including solderability and to be clearly superior in compatibility with the ~ang et al. por~elain-coated metal substrate boards. Films formed from the novel copper conductor inks of this invention demonstrate compatibility bo-th with films formed from conventional thick-film tin oxide or indium oxide resistor inks and resistor inks formulated to be compatible with the Hang et al.
porcelain-coated metal boards. The films likewise demonstrate good conductivity, solderability, solder leach resistance, wire bondability and resistance to long term exposure to high humidity.
The following Examples further illustrate this inven-tion, it being understood that the invention is in no way intended to be limited to the details described therein. In the Examples, all parts and percentages are on a weight basis and all temperatures are in degrees Celsius unless otherwise stated.
:
. .
,, - ~ ' .' 72~7 1 -6- RCA 75,431 Copper conductor :inks were prepared from the following formulations:
Percent by Weight Ingredient A B C D E
Copper Powder81.0881.08 81.08 79.37 81.08 Glass Frit* 3.24 2.16 1.08 2.11 ---Bi23 1.08 2.16 3.24 4.23 2.16 Commercial** -- --- --- --- 2.16 Pb/B/Si Glass Vehicle*** 14.60 14.60 14.60 14.29 14.60 * The glass frit had the following composition:
BaO 51.32 percent; CaO 12.51 percent; B2O3 19.42 percent; and sio2 16.75 percent.
** Exact formulation not available. Estima-ted lead oxide content 60 percent.
*** On a weight basis: 62.96 percent of a 6 percent solution of ethyl cellulose in the ester alcohol Texanol available from Texas Eastman Company; 18.52 percent Hypothiolate 100 wetting agent available from Cen-tral Compounding ~ ~25 Company, Chicago, Ill. (dispersion of hydroxyl ; ~ ~ containing, multifunctional aliphatic hydrocarbon in aliphatic hydrocarbon oil) and 18.52 percent of an 11.2 percent dispersion of the castor oil derivative Thixatrol, available from N.L.
30~ Industrles, in Texanol.
: ~ :
::
The~powder ingredients were combined with the organic vehicle, initiaIly mixed by hand and then on a 3 rol~l~ mil~l;with shearing to~obtain a smooth paste suitable 35 ~for screen printing. Additional vehlcle was added to replace loss during mixing and~-to assure proper rheology.
Conductor terminations~were printed with the thus formed inks on~a porcelain coated steel board of the type disclosed by Hang et al.~ using a stainless steel screen i-.J ~ ~ ~
"'' .
~L~6~Z~7 I -7~ RCA 75,431 (200 mesh, 1 mil emulsion). The terminations were dried in air at 125 for 15 minutes and then fired in ni-trogen ill a bel-t furnace at peak temperature of 850 ~ 10 for 8-12 minutes. Indium oxide resistor inks were then printed, dried in a similar manner and fired in nitrogen at 900 ~ 5 for 4-7 minutes at peak temperature. The resistor widths varied from 50 to 100 mils. The resistor inks utilized were prepared from the following formulations:
Percent by Weight Ingredient _ _ Indium Oxide 46.51 34.09 Glass I 27.91 ---Glass II --- 38.64 Magnesium Oxide --- 4.55 Ethyl Cellulose, 6 percent, 25.58 22.72 Solution in Texanol The glass frits utilized in the above resistor ink formulations had the following composition.
:
Percent by Weight ~SE__ient ~ I II
`Barium Oxide 50.32 51.59 Calcium Oxide 12.28 12.58 Boron Trioxide 19.05 15.62 Silicon Dioxide ~16.43 20.21 Cobalt Oxide 1.92 ---Average Particle Size 3.4 ~m 4.3 - 4.5 ~m The sheet resistance of each of the five copper conductor ~ilms was determined for each of the two resl~stors. The results are reported in Table I.
~ .
:: ::~: :
6~Z~7 1 -8~RCA 75,431 TABLE I
Conductor Sheet Resistance KQ/o Formulation I II
S A 9.8202.3 11.3297.3 C 16.3516.7 D 19.5882.3 E 28.9460.0 The data for formulations C and D demonstrate that, when the bismuth oxide content of the inks exceeds 3 percent, the sheet resistance begins to rise sharply.
Formulation E shows that, even if the bismuth oxide content of the copper ink is less than 3 weight percent, the presence of lead oxide in the glass causes an undesirable terminal point reaction.
A copper ink was prepared according to the procedure of Example 1 from the formulation designated "B". In this example, however, the bismuth oxide powder was added to the oxides melted to make the glass frit as opposed to being added to the~ink as a separate ingredient. Terminations were printed and fired on a conventional alumina board and two porcelain-coated steel boards of the type disclosed by Hang et al. The porcelains of the Hang et al.~,~ type boards had~the following composition~
30~ Weight Percent in Porcelain Ingredient~ A ~ B~
` Magnesium~Oxide ~ ~40.98~ ~ 27.96 Barium Oxlde ~ l8.82 37.34 Boron Triox~ide 24.41 16.96 ;35~ Silicon~Diox~ide~ ~ ~ 15.79~ 17.74 Two~commercial stannic oxide containing resistor inks~available~ from TRW,~Inc.,~Philadelphia, Pa. were : .. ~- , : : : -:
.
-1 _9_ RCA 75,431 printed and fired on the subs-trates in the manner of Example 1. The sheet resistivities are reported in Table II.
TABLE II
Sheet Resistance KQ/o Resistor Ink Alumina Porcelain A Porcelain B
TS104 30.8 51.9 341 TS105 119.8 142.9 1157 The high resistance readings for porcelain B are the result of the migration of iron into the porcelain which in turn reduces the stannic oxide in the commercial inks. The change in resistivity is due to the substrate and not the copper inks. The data in Table II further : demonstrates the compatibility of the copper conductor inks of this invention with various substrates as well as with films formed from commercial resistor inks.
~:~ 25 : : :
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.
.
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.
This invention relates to thick-film conductor inks and their use in multilayer electrical circuit structures on porcelain-coated metal boards.
BACKGROUND_OF T~E INVENTION
The use of specialized ink formulations to form thick films having various functions on suitable substrates in the construction of multilayer structures is well known in the art. Such technology is of increasing interest in the fabrication of very dense multilayer integrated clrcuit patterns on various substrates for a wide variety of applications in the electronics industry.
Significantly improved substrates for the fabrication of such circuits are disclosed and claimed in Hang et al., U.S. Patent No. 4,256,796, issued March 17, 1981. The Hang et al. substrates are metal coated with an improved porc01ain composition comprised of a mixture, based on its oxide content, of magnesium oxide (MgO~ or mixtures of magnesium oxide and certain other oxides, barium oxide (BaO), boron trioxide (B2O3~ and silicon dioxide (SiO2).
While the porcelain-coated metal substrates of Hang et al. represent a significant improvement over previously known substrate materials, they are disadvantageous only in being incompatible or poorly compatible with commercially a~ailable thick-film inks.
; This invention is concerned with improved coppe~ conductor inks compatible with the Hang et al. substrates.
It is generally recognized that it is advantageous to include bismuth oxide in copper conductor inks to improve the solderability of films formed therefrom. Conventionally, such inks contain from about 5 percent up to as much as 10 percent by weight bismuth oxide. We have found that bismuth oxide in amounts in excess of about 3 percent by weight of the ink formulation will frequently cause a reaction at the point of contact between a conductor film and a resistor. This results in ~, 672~ 7 l -2- RCA 75,431 a signiEicantly increased resistance at the point of contact, a distinct disadvantage.
In accordance with this invention, copper conductor inks are provided which are compatible with the Hang et al. substrates, and are characterized by good solderability without the aforementioned point of contact reaction with resistors.
SUMMARY OF THE INVENTION
The improved conductor inks of this inven-tion comprise a barium calcium borosilicate glass, copper powder, bismuth trioxide and a suitable organic vehicle.
DETAILED DESCRIPTION OF T~E INVENTION
In accordance with -this invention, there are provided improved copper conductor inks of high reliability useful in the production of complex single or multilayer thick-film circuits on suitable substrates, particularly the porcelain-coated metal circuit boards of Hang et al.
In addition -to being compatible with the porcelain of the Hang et al. substrates, the improved copper conductor inks of this invention are compatible with inks of other functions specifically formulated therefor. The subject copper conductor inks and other functional and pro-tec-tive inks formulated for the ~ang et al. porcelain-coated metal boards, together with the ~boards themselves, represent a significant advance in multiIayer thick-film integrated circuit structures.
~ The novel copper conductor inks of this 30 ~ invention are comprised of copper powder, a glass frit, bismuth oxide and a suitable organic vehicle.
The gIass frit of the cond-uctor inks of this invention is a barium calcium borosilicate glass which is compatible wi~h the porcelain of the Hang et al. boards.
3~ As a result, thich-film conductors prepared from the subject in~s have excellent reheat stability and thermal expansion properties similar to the Hang et al. substrate boards. In addition, by controlling the amount of bismuth oxide included in the inks of this invention, conductor ", ~
. ,~,. .. .. .
..
.
6~
I -3- RCA 75,431 thick-films formed from the inks of this inven-tion are not characterized by the aforementioned reaction at point of contact with resistors, yet possess the solderability conventionally associated with larger amounts of bismuth oxide.
The glass frit of the novel inks of this invention is a barium calcium borosilicate glass consisting of, on a weight basis:
a) from about 40 to about 55 percent, preferably about 52 percent, of barium oxide;
b) from about lO to about 15 percent, preferably about 12 percent, of calcium oxide;
c) from about 14 to about 25 percent, preferably about 16 percent, of boron trioxide; and d~ from about 13 to about 23 percent, preferably about 20 percent, of silicon dioxide. The glass frit comprises from about 1 to about 15 percent, preferably from about 2 to about 6 percent by weight, of the total ink cOmpOsition.
The copper powder utilized in the conductive inks of this invention is pure copper having a particle size of about 3.0 to 3.2 micrometers. The copper comprises from abou-t 70 to about 40 percent, preferably from about 7~ to about 82 percent by weight, of the subject ink compositions.
The conductor inks of this invention contain from about 0.5 to about 3.0 percent, preferably from about 1 to about 2 percent by weight, of bismuth oxide. It is critical that the bismuth oxide content does not exceed about 3 percent by weight of the total ink composition.
It i~s also necessary that the subjec-t inks contain no lead ; oxide since its presence will cause the same termination reactions, even where the bismuth oxide content is well below the 3 weight percent maximum. The bismuth oxide and the glass frit are preferably present in the subjec-t inks in a weight ratio of from about 1:1 to abou-t 1:3. The bismuth oxide may be added to the subject inks as a powder or may be present in the-glass frit itself.
''' ~'`'` ~' . ` ' `' ' '' ' i7~47 I -4- RCA 75,431 The oryanic vehicles are blnders such as, for example, cellulose derivatives, particularly ethyl cellulose, synthetic resins such as polyacrylates or methacrylates, polyesters, polyolefins and the like. In general, conventional vehicles utilized in inks of the type described herein may be used in the subject inks.
Preferred commercially available vehicles include, for e~ample, pure liquid polybutenes available as Amoco H-25 Amoco H-50~and Amoco I.-100 from Amoco Chemicals Corporation, poly n-butylmethacrylate available from E. I.
duPont de Nemours and Co., and the like.
The above resins may be utilized individually or in any combination of -two or more. A suitable viscosity modifier can be added to the resin material if desired.
These modifiers can be sol~ents such as those conventionally used in similar ink compositions, e.g. pine oil, terpineol, butyl carbitol acetate, an ester alcohol available from Texas Eastman Company under the trademark Texanol and the like, or solid materials such as, for example, a castor oil derivative available from N.L.
Industries under the trademark Thixatrol.
The vehicle of the subject inks may also contain ; up to about 25 percent by weight, preferably from about 10 to about 20 percent by weight, based on the vehicle, of a suitable wetting agent of the type conventionally used in copper conductor inks to aid in coating the particles of ~copper powder with the organic vehicle. As is the case with all components of the organic vehicle,the wetting 0 agent must fire cleanly in nitrogen, i.e., without leaving a carbonaceous residue.~ A preferred wet-ting agent is a dispersion of a complex multifunctional, aliphatic hydrocarbon in an aliphatic hydrocarbon oil available under the trademark Hypothiolate 100 from Central Compounding Company, Chicago, Illinois. The organic vehicle comprises from about ~to about 25 percent by weight, preferably from about 12 to about 15 percent by weight,~of the subject inks.
A~ n~ R~ :
'~
: :
. : .
lL:~6~
I -5- RCA 75,431 The improved copper conductor inks of this invention are applied to the substrate, e.g., conventional alumina boards or the improved porcelain-coated metal boards of Hang et al. by conventional means, i.e. screen printing, brushing, spraying and the like, with screen printing being preferred. The coating of ink is then dried in air at 100 - 125C for about 15 minutes. The resulting film is then fired in nitrogen at peak 10 -temperatures of from 850 to 950C. for from 4 to 10 minutes.
Films formed from the novel conductor inks of this invention have been demonstrated to be comparable with conventional copper conductor inks in all properties including solderability and to be clearly superior in compatibility with the ~ang et al. por~elain-coated metal substrate boards. Films formed from the novel copper conductor inks of this invention demonstrate compatibility bo-th with films formed from conventional thick-film tin oxide or indium oxide resistor inks and resistor inks formulated to be compatible with the Hang et al.
porcelain-coated metal boards. The films likewise demonstrate good conductivity, solderability, solder leach resistance, wire bondability and resistance to long term exposure to high humidity.
The following Examples further illustrate this inven-tion, it being understood that the invention is in no way intended to be limited to the details described therein. In the Examples, all parts and percentages are on a weight basis and all temperatures are in degrees Celsius unless otherwise stated.
:
. .
,, - ~ ' .' 72~7 1 -6- RCA 75,431 Copper conductor :inks were prepared from the following formulations:
Percent by Weight Ingredient A B C D E
Copper Powder81.0881.08 81.08 79.37 81.08 Glass Frit* 3.24 2.16 1.08 2.11 ---Bi23 1.08 2.16 3.24 4.23 2.16 Commercial** -- --- --- --- 2.16 Pb/B/Si Glass Vehicle*** 14.60 14.60 14.60 14.29 14.60 * The glass frit had the following composition:
BaO 51.32 percent; CaO 12.51 percent; B2O3 19.42 percent; and sio2 16.75 percent.
** Exact formulation not available. Estima-ted lead oxide content 60 percent.
*** On a weight basis: 62.96 percent of a 6 percent solution of ethyl cellulose in the ester alcohol Texanol available from Texas Eastman Company; 18.52 percent Hypothiolate 100 wetting agent available from Cen-tral Compounding ~ ~25 Company, Chicago, Ill. (dispersion of hydroxyl ; ~ ~ containing, multifunctional aliphatic hydrocarbon in aliphatic hydrocarbon oil) and 18.52 percent of an 11.2 percent dispersion of the castor oil derivative Thixatrol, available from N.L.
30~ Industrles, in Texanol.
: ~ :
::
The~powder ingredients were combined with the organic vehicle, initiaIly mixed by hand and then on a 3 rol~l~ mil~l;with shearing to~obtain a smooth paste suitable 35 ~for screen printing. Additional vehlcle was added to replace loss during mixing and~-to assure proper rheology.
Conductor terminations~were printed with the thus formed inks on~a porcelain coated steel board of the type disclosed by Hang et al.~ using a stainless steel screen i-.J ~ ~ ~
"'' .
~L~6~Z~7 I -7~ RCA 75,431 (200 mesh, 1 mil emulsion). The terminations were dried in air at 125 for 15 minutes and then fired in ni-trogen ill a bel-t furnace at peak temperature of 850 ~ 10 for 8-12 minutes. Indium oxide resistor inks were then printed, dried in a similar manner and fired in nitrogen at 900 ~ 5 for 4-7 minutes at peak temperature. The resistor widths varied from 50 to 100 mils. The resistor inks utilized were prepared from the following formulations:
Percent by Weight Ingredient _ _ Indium Oxide 46.51 34.09 Glass I 27.91 ---Glass II --- 38.64 Magnesium Oxide --- 4.55 Ethyl Cellulose, 6 percent, 25.58 22.72 Solution in Texanol The glass frits utilized in the above resistor ink formulations had the following composition.
:
Percent by Weight ~SE__ient ~ I II
`Barium Oxide 50.32 51.59 Calcium Oxide 12.28 12.58 Boron Trioxide 19.05 15.62 Silicon Dioxide ~16.43 20.21 Cobalt Oxide 1.92 ---Average Particle Size 3.4 ~m 4.3 - 4.5 ~m The sheet resistance of each of the five copper conductor ~ilms was determined for each of the two resl~stors. The results are reported in Table I.
~ .
:: ::~: :
6~Z~7 1 -8~RCA 75,431 TABLE I
Conductor Sheet Resistance KQ/o Formulation I II
S A 9.8202.3 11.3297.3 C 16.3516.7 D 19.5882.3 E 28.9460.0 The data for formulations C and D demonstrate that, when the bismuth oxide content of the inks exceeds 3 percent, the sheet resistance begins to rise sharply.
Formulation E shows that, even if the bismuth oxide content of the copper ink is less than 3 weight percent, the presence of lead oxide in the glass causes an undesirable terminal point reaction.
A copper ink was prepared according to the procedure of Example 1 from the formulation designated "B". In this example, however, the bismuth oxide powder was added to the oxides melted to make the glass frit as opposed to being added to the~ink as a separate ingredient. Terminations were printed and fired on a conventional alumina board and two porcelain-coated steel boards of the type disclosed by Hang et al. The porcelains of the Hang et al.~,~ type boards had~the following composition~
30~ Weight Percent in Porcelain Ingredient~ A ~ B~
` Magnesium~Oxide ~ ~40.98~ ~ 27.96 Barium Oxlde ~ l8.82 37.34 Boron Triox~ide 24.41 16.96 ;35~ Silicon~Diox~ide~ ~ ~ 15.79~ 17.74 Two~commercial stannic oxide containing resistor inks~available~ from TRW,~Inc.,~Philadelphia, Pa. were : .. ~- , : : : -:
.
-1 _9_ RCA 75,431 printed and fired on the subs-trates in the manner of Example 1. The sheet resistivities are reported in Table II.
TABLE II
Sheet Resistance KQ/o Resistor Ink Alumina Porcelain A Porcelain B
TS104 30.8 51.9 341 TS105 119.8 142.9 1157 The high resistance readings for porcelain B are the result of the migration of iron into the porcelain which in turn reduces the stannic oxide in the commercial inks. The change in resistivity is due to the substrate and not the copper inks. The data in Table II further : demonstrates the compatibility of the copper conductor inks of this invention with various substrates as well as with films formed from commercial resistor inks.
~:~ 25 : : :
~ ~5 ; ~ : :
.
.
i . . ~ .
.
Claims
-10- RCA 75,431 CLAIMS:
1. A copper conductor ink suitable for forming a conductor film on a circuit board comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
2. A conductor ink in accordance with Claim 1, wherein said ink comprises: from about 78 to about 82 percent by weight of copper powder; from about 2 to about 6 percent by weight of said glass frit; from about 1 to about 2 percent by of weight bismuth oxide; and from about 12 to about 15 percent by weight of said vehicle.
3. A conductor ink in accordance with Claim 1, wherein said glass frit has the composition:
a) from about 40 to about 55 percent by weight of barium oxide;
b) from about 10 to about 15 percent by weight of calcium oxide;
c) from about 14 to about 25 percent by weight of boron trioxide; and d) from about 13 to about 23 percent by weight of silicon dioxide.
4. A conductor ink in accordance with Claim 3, wherein said glass frit has the composition: about 52 percent by weight of barium oxide; about 12 percent by weight of calcium oxide; about 16 percent by weight of boron trioxide; and about 20 percent by weight of silicon dioxide.
-11- RCA 75,431 5. A conductor ink in accordance with Claim 1, wherein said organic vehicle contains up to about 25 percent by weight, based on the vehicle, of a suitable wetting agent.
6. A conductor ink in accordance with Claim 5, wherein said wetting agent comprises from about 10 to about 20 percent by weight of said vehicle.
7. A conductor ink in accordance with Claim 1, wherein bismuth oxide is present in admixture with the copper powder.
8. A conductor ink in accordance with Claim 1, wherein bismuth oxide is present as a component of the glass frit.
9. A conductor ink in accordance with Claim 1, wherein the weight ratio of bismuth oxide to said glass frit is from about 1:1 to about 1:3.
10. A circuit board having on a portion of the surface thereof a coating of a conductor ink comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
A circuit board in accordance with Claim 10. wherein said board is porcelain-coated metal.
-12- RCA 75,431 12. A process for forming a conductor film as part of a circuit on a suitable circuit board comprising applying and firing onto said board an ink composition comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
13. An electronic assembly comprising a circuit board having a circuit thereon, said circuit containing a conductor film formed by applying and firing a conductor ink comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
14. An electronic assembly in accordance with Claim 13, wherein said circuit board is a porcelain-coated metal circuit board.
1. A copper conductor ink suitable for forming a conductor film on a circuit board comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
2. A conductor ink in accordance with Claim 1, wherein said ink comprises: from about 78 to about 82 percent by weight of copper powder; from about 2 to about 6 percent by weight of said glass frit; from about 1 to about 2 percent by of weight bismuth oxide; and from about 12 to about 15 percent by weight of said vehicle.
3. A conductor ink in accordance with Claim 1, wherein said glass frit has the composition:
a) from about 40 to about 55 percent by weight of barium oxide;
b) from about 10 to about 15 percent by weight of calcium oxide;
c) from about 14 to about 25 percent by weight of boron trioxide; and d) from about 13 to about 23 percent by weight of silicon dioxide.
4. A conductor ink in accordance with Claim 3, wherein said glass frit has the composition: about 52 percent by weight of barium oxide; about 12 percent by weight of calcium oxide; about 16 percent by weight of boron trioxide; and about 20 percent by weight of silicon dioxide.
-11- RCA 75,431 5. A conductor ink in accordance with Claim 1, wherein said organic vehicle contains up to about 25 percent by weight, based on the vehicle, of a suitable wetting agent.
6. A conductor ink in accordance with Claim 5, wherein said wetting agent comprises from about 10 to about 20 percent by weight of said vehicle.
7. A conductor ink in accordance with Claim 1, wherein bismuth oxide is present in admixture with the copper powder.
8. A conductor ink in accordance with Claim 1, wherein bismuth oxide is present as a component of the glass frit.
9. A conductor ink in accordance with Claim 1, wherein the weight ratio of bismuth oxide to said glass frit is from about 1:1 to about 1:3.
10. A circuit board having on a portion of the surface thereof a coating of a conductor ink comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
A circuit board in accordance with Claim 10. wherein said board is porcelain-coated metal.
-12- RCA 75,431 12. A process for forming a conductor film as part of a circuit on a suitable circuit board comprising applying and firing onto said board an ink composition comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
13. An electronic assembly comprising a circuit board having a circuit thereon, said circuit containing a conductor film formed by applying and firing a conductor ink comprising:
a) from about 70 to about 90 percent by weight of copper powder;
b) from about 1 to about 15 percent by weight of a barium calcium borosilicate glass frit;
c) from about 0.5 to about 3 percent by weight of bismuth oxide, wherein bismuth oxide is present in admixture with the copper powder or as a component of the glass frit; and d) from about 6 to about 25 percent by weight of a suitable organic vehicle.
14. An electronic assembly in accordance with Claim 13, wherein said circuit board is a porcelain-coated metal circuit board.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8033564 | 1980-10-17 | ||
| GB8033564 | 1980-10-17 | ||
| US280,917 | 1981-07-06 | ||
| US06/280,917 US4376725A (en) | 1980-10-17 | 1981-07-06 | Conductor inks |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1167247A true CA1167247A (en) | 1984-05-15 |
Family
ID=26277247
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000388159A Expired CA1167247A (en) | 1980-10-17 | 1981-10-16 | Conductor inks |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1167247A (en) |
| DE (1) | DE3140969A1 (en) |
| FR (1) | FR2492395B1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1173644A (en) * | 1981-07-06 | 1984-09-04 | Ashok N. Prabhu | Air-fireable thick film inks |
| EP0452118B1 (en) * | 1990-04-12 | 1996-08-21 | Matsushita Electric Industrial Co., Ltd. | Conductive ink composition and method of forming a conductive thick film pattern |
| JP2011091114A (en) * | 2009-10-20 | 2011-05-06 | Nitto Denko Corp | Printed circuit board and method of manufacturing the same |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2118696A5 (en) * | 1970-12-17 | 1972-07-28 | Du Pont | |
| US4122232A (en) * | 1975-04-21 | 1978-10-24 | Engelhard Minerals & Chemicals Corporation | Air firable base metal conductors |
| US4070518A (en) * | 1976-10-15 | 1978-01-24 | E. I. Du Pont De Nemours And Company | Copper metallizations |
| US4172919A (en) * | 1977-04-22 | 1979-10-30 | E. I. Du Pont De Nemours And Company | Copper conductor compositions containing copper oxide and Bi2 O3 |
| US4256796A (en) * | 1979-11-05 | 1981-03-17 | Rca Corporation | Partially devitrified porcelain composition and articles prepared with same |
-
1981
- 1981-10-15 DE DE19813140969 patent/DE3140969A1/en active Granted
- 1981-10-16 FR FR8119526A patent/FR2492395B1/en not_active Expired
- 1981-10-16 CA CA000388159A patent/CA1167247A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2492395A1 (en) | 1982-04-23 |
| FR2492395B1 (en) | 1985-11-29 |
| DE3140969C2 (en) | 1991-01-03 |
| DE3140969A1 (en) | 1982-06-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |