Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
  • F24C7/00—Stoves or ranges heated by electric energy
  • F24C7/06—Arrangement or mounting of electric heating elements

Definitions

• the present invention relates to a thick film substance, in particular a thick film paste, from an active component, in particular to define the substance properties serves, and a flux that connects to one to be coated Causes substrate. Furthermore, it relates to a manufacturing method a structure from a thick-film substance on a substrate.
• Such a paste and such a method are known for household appliances the publication DE 33 02 794 A1, with resistance elements on a baking muffle of an electric cooker are printed in thick-film technology for heating the muffle.
• the heating element consists of a known resistance paste from the outside is printed on the muffle wall.
• thick-film structures on any base material or subtract generally known e.g. from Peter Hauptmann: sensors, principles and applications; Carl Hanser publishing house.
• a screen printing process is used Thick film paste applied to the substrate, which is then at 100 ° C to 200 ° C dried and then baked at temperatures above 500 ° C.
• Thin steel or nylon screens are used to print the stencils and through which the pastes are pressed.
• a substrate material Usually ceramic, enamelled steel, glass or flexible plastic substrates are used.
• the thick film paste generally consists of an active component, e.g. Metal, metal oxide or ceramic, a flux, for example glass frit or bismuth oxide, and organic solvents and binders.
• the pastes in their physical-technical properties, such as toughness, coefficient of thermal expansion or temperature coefficient of resistance can be varied.
• passive components and Circuit protection today are commercially available conductor, masking, resistance and Dielectric pastes available.
• Resistance pastes contain frit material and binders predominantly metal oxides e.g. Rothenium and / or rhodium oxide.
• Thick film pastes are increasingly used on thick film powder.
• the object of the present invention is to create the free layout when creating to improve thick-film structures on substrates.
• this is a thick-film substance according to the preamble of Claim 1 achieved in that the thick-film substance at least one organic Contains reactive substance with a chemically reactive component by suitable energy input limited to the locations of the energy input with the substrate and can be crosslinked with the remaining constituents of the thick-film substance.
• the Corresponding method according to the invention is characterized in that initially the substrate is coated over a large area with the thick-film substance, then selectively attaching the thick-film substance to the substrate according to the desired substance structure by locally limited to the structure suitable energy input and finally by removing the unattached Thick film substance from the substrate.
• the Adhesion of the thick-film substance structure thus produced is in the Difference from the prior art according to the invention due to the chemical bond the structure of the substance is particularly good.
• the reactive substance is advantageously formed by a resin.
• a resin When energy input With UV light, for example, acrylic resin is suitable, while with infrared radiation Epoxy resin is an inexpensive solution at low temperatures.
• the surfaces of the remaining components of the thick-film substance can also be special suitably matched to the properties of the reactive component or the substrate if they are manufactured or processed using the sol-gel technique are.
• the thick-film substance is advantageously removed after the unattached one has been removed Branded thick film substance.
• this can be the case with the manufacturing process be carried out by yourself or when commissioning the device, in which the thick-film substance structure is provided by an operator.
• the thick-film substance is replaced by a Thick film paste is formed and by means of dipping or spraying onto the substrate is applied.
• the large area Coating of the substrate can also be done electrostatically.
• the properties of the thick-film structure for example its resistance value or their adherence to the substrate to permanently define the reactive substance removed from or during the introduction of the thick-film substance.
• the muffle wall serves as a substrate, both made of suitable metal or other Materials such as Non-conductive materials can exist.
• a suitable electrical insulation layer is preferred using sol-gel technology deposited on the muffle wall or the substrate. This turns into a solution (Sol) a colloidal system on a ⁇ scale through controlled condensation methods (Gel) generated. This gel is made by drying due to solvent removal compressed and then cured by introducing a suitable energy.
• the sol gel layer is chemically attached to the substrate or the Muffle wall bound, which leads to a particularly good adhesion of the layer on the Leads substrate.
• the necessary Layer thicknesses are less than 10 ⁇ m, which causes the thermomechanical stresses in the insulation layer with operational temperature increases clearly be reduced.
• the heat transfer is due to the small layer thickness the insulation layer improved.
• the transparent or colored sol-gel insulation layer serves as an electrical insulation as well as the requirement functional surface for the wear side, i.e. the inside of the muffle.
• a thick-layer heating conductor substance is first used produced, which in their composition a proportion of a contains reactive organic or organosilicon components.
• This reactive component opens up the possibility of defining the thick-film structure and to fix that the proportions of the reactive component targeted each other be networked.
• the initially liquid, pasty or powdery thick-film substance defined structured and to a homogeneous, stable and am Solidified substrate or intermediate product adhering to the electrical insulation layer.
• the crosslinking itself can be effected by the action of initiators, e.g.
• the heating conductor structure is generated as follows:
• the thick-film paste is sprayed over a large area into the desired one Areas applied to the outside of the oven muffle. After that is done the selective connection of the desired heating conductor structure or the heating conductor layout on the substrate. With the help of a corresponding structure mask they will not shielded areas of the heating conductor paste.
• the thick-film paste becomes energy input, for example a UV or IR exposure process selectively pre-hardened in the non-masked areas and to the Chemically bound substrate.
• the reactive component of the heating conductor paste activated and networked by the energy input. Through this networking, the Heating conductor paste sufficient strength for the further process steps and Adhesion to the substrate or the electrical insulation layer.
• this is Process when using a focused energy source, e.g. a laser too possible without mask.
• a focused energy source e.g. a laser too possible without mask.
• the insulation layer bound portion of the thick layer paste For example done in a rinsing process. So that is also on a substrate with a not flat, but, for example, channel-shaped or groove-shaped profile a thick-film heating conductor structure possible. It just has to be structured Energy input and thus the structured networking of the thick-film substance ensured be.
• the final connection of the heating conductor to the substrate can then, for example in a baking oven, which is heated electrically by IR radiation or flash lamps becomes.
• a baking oven which is heated electrically by IR radiation or flash lamps becomes.
• the area of application of the heating conductor is below 250 ° C, the baking temperature should not exceed 250 ° C.
• This especially low process temperatures are particularly due to the sol technical Preparation of the reactive component and the other components of the thick-film substance possible.
• the Substance to ensure that this is a continuous use temperature in height the desired later operating temperature, otherwise it would be due to the unintentional degradation of the reactive component to undesirable changes
• the electrical characteristics of the heating conductor can come.
• the curing can take place by applying a voltage to the thick-film heating conductor.
• the heat conductor heats up due to the current flow, causing it to reach the desired level Degree is cured.
• This curing can already take place during the The heating conductors are checked for functionality or only when the oven is started up by an operator.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing Of Printed Wiring (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Paints Or Removers (AREA)
• Parts Printed On Printed Circuit Boards (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=7868007

Family Applications (1)

Country Status (2)

Cited By (2)

Family Cites Families (7)

• 1998
  • 1998-05-15 DE DE1998122033 patent/DE19822033A1/de not_active Ceased
• 1999
  • 1999-05-11 EP EP99109459A patent/EP0964410A3/fr not_active Withdrawn

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