US3922386A - Process for the manufacture of small heat-generating printed circuits - Google Patents

Process for the manufacture of small heat-generating printed circuits Download PDF

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Publication number
US3922386A
US3922386A US327027A US32702773A US3922386A US 3922386 A US3922386 A US 3922386A US 327027 A US327027 A US 327027A US 32702773 A US32702773 A US 32702773A US 3922386 A US3922386 A US 3922386A
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US
United States
Prior art keywords
metal
coating
ceramic
substrate
oxide
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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 - Lifetime
Application number
US327027A
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English (en)
Inventor
Bonifacio Echavarri Ros
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Orbaiceta SA
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Orbaiceta SA
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    • 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
    • H05K1/03—Use of materials for the substrate
    • H05K1/05—Insulated conductive substrates, e.g. insulated metal substrate
    • H05K1/053—Insulated conductive substrates, e.g. insulated metal substrate the metal substrate being covered by an inorganic insulating layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/347—General aspects dealing with the joint area or with the area to be joined using particular temperature distributions or gradients; using particular heat distributions or gradients
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/13—Moulding and encapsulation; Deposition techniques; Protective layers
    • H05K2203/1333—Deposition techniques, e.g. coating
    • H05K2203/1344—Spraying small metal particles or droplets of molten metal
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/901—Printed circuit

Definitions

  • a heating element appropriate for use with printed circuits and which is itself a printed circuit comprises a filament consisting of a mixture of aluminum and aluminum oxide, the resistivity of the heating element .formed of the filament being adjustable by varying the thickness of the filament.
  • the filament is supported on a ceramic coating on a metal substrate.
  • a metal substrate preferably iron with a carbon content of less than 0.04% is coated with successive thin layers of a ceramic and fired, the objective of using a plurality of ceramic layers being to avoid pin holes 7 which are continuous from the surface of the ceramic to the substrate.
  • the coating is then sprayed with a mixture of aluminum and aluminum oxide using a spray gun to spray molten aluminum globules in an oxidizing atmosphere.
  • the layer of mixed aluminum and aluminum oxide which results is screen-printed with a resist small heating elements in the form of a printed circuit.
  • Another object of the present invention is to provide an improved process for the manufacture of a heating element consisting of aluminum and aluminum oxide or zinc or copper and their oxides.
  • a further object of the present invention is to provide a method for the production of a heating element consisting of aluminum and aluminum'oxide on a ceramic base supported on a metal substrate. Zinc and copper in combination with their oxides will also serve.
  • An important object of the present invention is to provide an improved miniature heating element suitable for use with voltages as high as 220 volts or higher.
  • a significant object of the present invention is to provide an improved miniature heating element wherein the resistance of the heating element can be controlled by the quantity of mixed aluminum and aluminum oxide or zinc and copper with their oxides deposited on a base.
  • Yet another object of the present invention is a miniature heating element comprising a mixture of aluminum and aluminum oxide or of zinc and zinc oxide or of copper and copper oxide as the conductive element, the mixture being adherent to a coating of ceramic on a metal substrate.
  • the invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the composition possessing the features, properties, and the relation of constituents, which are exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.
  • FIG. 1 is a schematic sectional view of a ceramiccoated metal plate in accordance with the prior art showing flaws or pinholes reaching from the surface of the ceramic coating to the metallic substrate;
  • FIG. 2 is a ceramic-coated metal plate in accordance with the present invention.
  • FIG. 3 is a sectional view in perspective of a fragment of a heating element in accordance with the present invention.
  • FIG. 1 Such a ceramic-coated metallic substrate is shown in FIG. 1 where the ceramic coating 2 is applied on the metallic substrate 1 in accordance with the prior art as a single layer on each side of the metallic substrate 1. As indicated schematically, ceramic coatings generally have flaws in the form of minute holes indicated by the indentations given the reference numeral 20 in FIG. 1. If a heating element were imposed on a perforate layer 2 such as is shown in FIG. 1, the heating element would make contact with the metal substrate 1 at several points, thus, effectively shorting out the heating element.
  • a ceramic coating generally represented by the reference numeral 8 is applied to the metal substrate 1 as shown in FIG. 2.
  • the ceramic coating 8 consists of a plurality of layers, in this case 3 layers, having the refertremely small so that the danger of a short or multiple ence numerals 3, 4 and 5.
  • layer 3 has pinholes 3a
  • layer 4 has pinholes 4a
  • layer 5 has pinholes 5a.
  • the probability of pinholes in each successive layer being coincident is exshorts between the heating elements to be superimposed upon the ceramic coating 8 is extremely small.
  • each layer is fired and cooled prior to application of the next layer. Consequently each successive layer tends to fill in the pinholes in the previous layer thereby substantially eliminating the possibility of a short between the heating element and the substrate 1.
  • the substrate 1 may be of any metal which can be fired to a high enough temperature so that the ceramic will vitrify
  • a preferred substrate is iron having a carbon content no greater than 0.04%.
  • a suitable thickness for the substrate is I millimeter although this can be varied in accordance with the degree of rigidity needed and the weight which can be tolerated.
  • the advantage of iron of the composition specified is that no significant structural changes will take place during and after the vitrifying treatment.
  • the system stand for several days so that any improper operation in preparing the coated substrate will become evident in the form of cracks or scaling.
  • the piece After passing inspection with regard of the integrity of the coating on the metal sub- 3 strate, the piece is carefully cleaned and degreased before application of the resistive element. Any residue of oil or perspiration from the fingers will impair the adhesion of the resistive element to the ceramic coating.
  • the temperature of the support is raised to just below that at which softening of the ceramic coating occurs or the ceramic coating becomes pasty.
  • the support in this condition provides the best adhesion for the resistive element to be applied by spraying.
  • the piece is then sprayed with aluminum, copper or zinc particles projected from a metal-spray gun.
  • the operation is carried out in an oxidizing atmosphere such as air so that the spheroids of metal produced become oxidized on the surfaces thereof to form a corresponding metal oxide.
  • the preferred metal is aluminum.
  • the aluminum may be fed to the metal-spray gun in any convenient form such as powder or wire. it is also desirable that the aluminum be of high purity, since with impurities of unknown amount and unknown type present in the aluminum, the resistivity of the deposited heating element will vary in uncontrolled fashion.
  • the aluminum As the aluminum is fused in passing through the nozzle of the metal-spray gun it is subjected to an oxidizing flame, and ejected from the gun by air pressure. Conditions should be such that the spheroidal particles have a diameter of about 8 microns though the actual size is not crucial, so long as it is reproducible.
  • a thin layer of aluminum oxide is formed on the surface of the particles, the cores of the particles remaining molten until the particles strike against the surface to be metalized. The particles then break and spatter, the molten metal spattering as it strikes the support and solidifying quickly to form a coating with aluminum oxide inclusions.
  • the temperature of the support must be below the melting point of the metal sprayed thereon.
  • the metal-spraying process can be repeated, depositing a succession of metal layers containing oxide and allowing the coated substrate to cool after deposition of each layer. The process can be repeated until the metal-metal oxide coating is of the desired thickness.
  • the presence of the metal oxide inclusions greatly increases the resistivity of the deposited film.
  • the resistivity of the finished element can be controlled by the quantity of mixed metal and metal oxide deposited on the support. For many uses it has been found convenient to deposit thicknesses as great as 35 microns but, as is obvious, there is actually no practical limit to the thickness of the mixed metal metal oxide coating which can be applied in this way.
  • the resistivity of the coating is so high, and, due to the fact that, in general, the power dissipated is relatively small, such coatings are sutiable for use with voltages as high as 220 and even higher. It should be noted that the resistivity of films deposited in this way is so much higher than that of the metal alone that were the metal alone to be deposited under conditions such that oxidation is to be avoided, then it would be necessary to restrict the thickness of the deposit to about 2 microns which would render the element very susceptible to mechanical damage as well as to failure due to the presence of flaws in the coating.
  • Coatings prepared in accordance with the present invention particularly those of aluminum and aluminum oxide, have a much higher resistivity than that of the metal alone so that it is convenient to prepare relatively thick coatings of the combination which are tightly adherent to the support, mechanically strong and which can be adjusted to the desired total resistance after shaping by means of the shaping oper'ation itself, or even by surface grinding.
  • the metal-metal oxide coating After depositing the metal-metal oxide coating, it can be silk-screened in the usual way to deposit a resist of any desired shape. After drying of the resist, the resistive element is shaped to the desired form by etching by conventional means. Finally, the resist is removed from the product by vapor-degreasing using perchlorethylene or any similar solvent.
  • a process of manufacturing small printed circuits for the generation of heat comprising the steps of depositing a ceramic dielectric coating on a metal substrate, allowing the ceramic-coated substrate to stand at room temperature for a period long enough for any defects in said ceramic coating to become evident, degreasing said ceramic coating, depositing from a metalspray gun an adherent conductive coating of a metal chosen from the group consisting of aluminum, zinc and copper mixed with the oxide of said chosen metal on said ceramic coating, said ceramic-coated substrate having'been preheated to a temperature sufficient to provide good adhesion thereto of said sprayed conductive coatings, said adherent conductive coating having a resistivity much higher than that of the metal alone as the result of inclusion of the metal oxide therein, depositing a resist on said adherent conductive coating and shaping said conductive coating into a desired form by etching.
  • said adherent conductive coating is deposited from a metalspray gun in the form of molten droplets each coating with a thin film of metal oxide, said coated droplets being formed by spraying pure molten metal droplets through an oxidizing atmosphere onto said coated substrate, said droplets breaking, spattering and solidifying on deposition.
  • a small printing circuit suitable for the generation of heat comprising a metal substrate, a plurality of individually fired ceramic coatings on said metal substrate, said ceramic coatings being free of scaling,
  • shaped coating of a flame sprayed metal containing inclusions of its oxide in sufficient quantity so that the resistivity of said shaped coating makes said circuit suitable for use at voltages as high as 220 volts, said metal being selected from the group consisting of aluminum, zinc and copper.
  • a process of manufacturing small printed circuits for the generation of heat comprising the steps of firing and coating a plurality of ceramic coatings on an iron substrate containing not more that 0.04% of carbon, allowing said coated substrate to stand at room temperature for several days to permit any flaws on said ceramic coatings to become evident, cleaning and degreasing said coated substrate, heating said ceramiccoated substrate to a temperature sufficiently high to provide good adhesion between a sprayed-on metal film and said coated substrate, spraying said heated ceramic-coated substrate with molten droplets of a metal coated with its oxide by means of a metal-spray gun with an oxidizing flame in an oxidizing atmosphere, said metal being selected from the group consisting of aluminum, copper and tin, said droplets on striking said coated substrate spattering and solidifying to form a film including metal oxide dispersed therein, allowing said film to cool to room temperature, repeating the metal-spraying and cooling to form a succession of metal layers until the deposit of metal including metal oxide reaches a desired thickness,

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Surface Heating Bodies (AREA)
  • Resistance Heating (AREA)
  • Coating By Spraying Or Casting (AREA)
US327027A 1972-04-12 1973-01-26 Process for the manufacture of small heat-generating printed circuits Expired - Lifetime US3922386A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ES401673A ES401673A1 (es) 1972-04-12 1972-04-12 Mejoras introducidas en la fabricacion de circuitos impre- sos de pequeno formato para generacion de calor.

Publications (1)

Publication Number Publication Date
US3922386A true US3922386A (en) 1975-11-25

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US327027A Expired - Lifetime US3922386A (en) 1972-04-12 1973-01-26 Process for the manufacture of small heat-generating printed circuits

Country Status (6)

Country Link
US (1) US3922386A (cs)
AT (1) AT318098B (cs)
CH (1) CH552328A (cs)
ES (1) ES401673A1 (cs)
FR (1) FR2180635B1 (cs)
GB (1) GB1391814A (cs)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4093755A (en) * 1975-01-31 1978-06-06 The Gates Rubber Company Method for making a liquid heat exchanger coating
DE3143691A1 (de) * 1981-11-04 1983-05-11 E.G.O. Elektro-Geräte Blanc u. Fischer, 7519 Oberderdingen Steuerbeheizung fuer ein leistungssteuergeraet
EP0103977A1 (en) * 1982-08-16 1984-03-28 E.I. Du Pont De Nemours And Company Improved sterile docking cutting means
US4501713A (en) * 1983-06-15 1985-02-26 Phillips Petroleum Company Stabilizing melt crystallization temperature in arylene sulfide polymer heat treatment
US4916260A (en) * 1988-10-11 1990-04-10 International Business Machines Corporation Circuit member for use in multilayered printed circuit board assembly and method of making same
US6127654A (en) * 1997-08-01 2000-10-03 Alkron Manufacturing Corporation Method for manufacturing heating element
US20020096512A1 (en) * 2000-11-29 2002-07-25 Abbott Richard C. Resistive heaters and uses thereof
US20050023218A1 (en) * 2003-07-28 2005-02-03 Peter Calandra System and method for automatically purifying solvents
EP2273182A3 (de) * 2009-07-07 2011-05-11 Siteco Beleuchtungstechnik GmbH Dreidimensionales LED-Trägerelement mit thermischer Leitfähigkeit
EP2273181A3 (de) * 2009-07-07 2011-05-11 Siteco Beleuchtungstechnik GmbH Trägerelement für LED-Modul
GB2577522A (en) * 2018-09-27 2020-04-01 2D Heat Ltd A blend, coating, methods of depositing the blend, heating device and applications therefore

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4491622A (en) * 1982-04-19 1985-01-01 Olin Corporation Composites of glass-ceramic to metal seals and method of making the same
US4851615A (en) * 1982-04-19 1989-07-25 Olin Corporation Printed circuit board
EP0139030B1 (en) * 1983-10-19 1989-08-09 Olin Corporation Improved printed circuit board

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2971867A (en) * 1957-12-19 1961-02-14 Pittsburgh Plate Glass Co Coating surfaces
US3067310A (en) * 1959-12-02 1962-12-04 Frank C Walz Microfilm electric heaters
US3396055A (en) * 1965-04-16 1968-08-06 Vitreous Steel Products Compan Radiant heating panels and resistive compositions for the same
US3791863A (en) * 1972-05-25 1974-02-12 Stackpole Carbon Co Method of making electrical resistance devices and articles made thereby
US3821019A (en) * 1970-11-27 1974-06-28 Rockwell International Corp Electrically-conductive ceramic-metallic protective coating

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2971867A (en) * 1957-12-19 1961-02-14 Pittsburgh Plate Glass Co Coating surfaces
US3067310A (en) * 1959-12-02 1962-12-04 Frank C Walz Microfilm electric heaters
US3396055A (en) * 1965-04-16 1968-08-06 Vitreous Steel Products Compan Radiant heating panels and resistive compositions for the same
US3821019A (en) * 1970-11-27 1974-06-28 Rockwell International Corp Electrically-conductive ceramic-metallic protective coating
US3791863A (en) * 1972-05-25 1974-02-12 Stackpole Carbon Co Method of making electrical resistance devices and articles made thereby

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4093755A (en) * 1975-01-31 1978-06-06 The Gates Rubber Company Method for making a liquid heat exchanger coating
DE3143691A1 (de) * 1981-11-04 1983-05-11 E.G.O. Elektro-Geräte Blanc u. Fischer, 7519 Oberderdingen Steuerbeheizung fuer ein leistungssteuergeraet
EP0103977A1 (en) * 1982-08-16 1984-03-28 E.I. Du Pont De Nemours And Company Improved sterile docking cutting means
US4501951A (en) * 1982-08-16 1985-02-26 E. I. Du Pont De Nemours And Company Electric heating element for sterilely cutting and welding together thermoplastic tubes
US4501713A (en) * 1983-06-15 1985-02-26 Phillips Petroleum Company Stabilizing melt crystallization temperature in arylene sulfide polymer heat treatment
US4916260A (en) * 1988-10-11 1990-04-10 International Business Machines Corporation Circuit member for use in multilayered printed circuit board assembly and method of making same
US6127654A (en) * 1997-08-01 2000-10-03 Alkron Manufacturing Corporation Method for manufacturing heating element
WO2002059936A3 (en) * 2000-11-29 2003-02-06 Thermoceramix Lcc Resistive heaters and uses thereof
US20020096512A1 (en) * 2000-11-29 2002-07-25 Abbott Richard C. Resistive heaters and uses thereof
US6919543B2 (en) * 2000-11-29 2005-07-19 Thermoceramix, Llc Resistive heaters and uses thereof
EP1346607A4 (en) * 2000-11-29 2006-12-13 Thermoceramix Llc RESISTIVE HEATING ELEMENTS AND USES THEREOF
US20050023218A1 (en) * 2003-07-28 2005-02-03 Peter Calandra System and method for automatically purifying solvents
EP2273182A3 (de) * 2009-07-07 2011-05-11 Siteco Beleuchtungstechnik GmbH Dreidimensionales LED-Trägerelement mit thermischer Leitfähigkeit
EP2273181A3 (de) * 2009-07-07 2011-05-11 Siteco Beleuchtungstechnik GmbH Trägerelement für LED-Modul
GB2577522A (en) * 2018-09-27 2020-04-01 2D Heat Ltd A blend, coating, methods of depositing the blend, heating device and applications therefore
WO2020065612A1 (en) 2018-09-27 2020-04-02 2D Heat Limited A heating device, applications therefore, an ohmically resistive coating, a method of depositing the coating using cold spray and a blend of particles for use therein
GB2577522B (en) * 2018-09-27 2022-12-28 2D Heat Ltd A heating device, and applications therefore
US12250753B2 (en) 2018-09-27 2025-03-11 2D Heat Limited Heating device, applications therefore, an ohmically resistive coating, a method of depositing the coating using cold spray and a blend of particles for use therein

Also Published As

Publication number Publication date
CH552328A (de) 1974-07-31
AT318098B (de) 1974-09-25
ES401673A1 (es) 1972-07-01
GB1391814A (en) 1975-04-23
FR2180635A1 (cs) 1973-11-30
FR2180635B1 (cs) 1978-10-20

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