THIN FIlM TYPE HEATER AND METHODOF MANUFACTURING THE SAMEThe present invention relates to a thin film type heater used as a heat source in a boiler type humidifier or a water heater, and a method of manufacturing the same.
In general, a boiler type humidifier generates vapours by heating water in a water tank and blows the vapours through a ventilator. In doing so, the amount of heat of the heater should be controlled to control the amount of vapor generated. The heater adapted for the boiler type humidifier mainly employs a nichrome wire or a bar heater having a desired resistance. The amount of heat of the heater changes by changing the resistance of an electrical contact, or by controlling the current passing through the heater.
In the conventional heater, the initial heating time required for normal humidification is high, and the contact point between electrodes may be short due to excess heat generated at the contact point.
With a view to solve or reduce the above problems, it is an aim of embodiments of the present invention to provide a thin film type heater in which a material having good electric resistance is employed to maximize an instantaneous heating efficiency capable of being miniaturized, and a method of manufacturing the same.
According to an aspect of the invention, there is provided a thin film type heater comprising: a substrate; a plurality of unit heating layers coated on the substrate in a predetermined pattern; an electrode layer for interconnecting the unit heating layers to form a current path; and a protective layer coated on the substrate for protecting the heating layer and the electrode layer.
Preferably, the heating layer is formed of one selected from the group consisting of TaAl, Ni-Cr alloy,SnO2, HfB2 and Ta.
The heater may comprise a connection terminal for supplying current to the heating layer.
Preferably, the electrode layer is formed of one selected from the group consisting of Al, Au, Ag, RuO2 andPt.
The protective layer may be formed of one selected from the group consisting of Si3N4, SiO2 and SiC.
The protective layer is preferably formed along upper surfaces of the heating layer and the electrode layer to have a predetermined thickness.
According to another aspect of the invention, there is provided a method of manufacturing a thin film type heater comprising the steps of: (a) coating a thin film on a substrate with one selected from the group consisting ofTaAl, Ni-Cr alloy, Sino2, HfB2 and Ta in a predetermined pattern to from a unit heating layer; (b) forming an electrical path by interconnecting the unit heating layers to an electrode layer on the substrate; and (c) forming a protective layer on the substrate to protect the heating layer and the electrode layer.
For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:Figure 1 is a schematic sectional view of a thin film type heater according to an embodiment of the present invention;Figure 2 is a schematic plan view of the thin film type heater of Figure 1; andFigures 3A through 3C are plan views for illustrating a method of manufacturing a thin film type heater according to embodiments of the present invention.
Referring to Figures 1 and 2, a thin film type heater according to an embodiment of the present invention comprises a plurality of unit heating layers 20 coated on a substrate 10 in a predetermined pattern, an electrode layer 30 coated on the substrate 10 interconnecting the unit heating layers 20 to form a current path, and a protective layer 40 coated on the unit heating layers 20, the electrode layer 30 and the substrate 10 for protecting the heating layers 20 and the electrode layer 30.
Reference numeral 31 indicates a connection terminal for supplying current to the heating layer 20, which is electrically connected to a main circuit substrate of, for instance, a boiler-type humidifier or a water heater through wire-bonding.
Preferably, the substrate 10 is a glass substrate, and the heating layer 20, the electrode layer 30 and the protective layer 40 are formed through a dry coating method such as PVD or CVD using a metal mask.
It is also preferable that the heating layer 20 is coated with a material selected from the group consisting of TaAl, Ni-Cr alloy, SnO2, HfB2 and Ta, and the electrode layer 30 is coated with a material selected from the group consisting of Al, Au, Ag, RuO2 and Pt having high electrical conductivity.
The protective layer 40 formed of a dielectric is coated with a material selected from the group consisting of Si3N4, SiO2 and SiC, along the upper surface line of the heating layer 20 and the electrode layer 30.
When current is applied through the connection terminal 31, the current flows to the unit heating layers 20 through the electrode layer 30, to thereby generate heat from the unit heating layers due to their electrical resistance. The material used for the heating layer 20 has a high electrical resistance so that it heats up to a desired temperature in a short time.
A method of manufacturing the thin film type heater will be described with reference to Figures 3A through 3C.
As shown in Figure 3A, a metal mask (not shown) where a unit heating layer pattern is formed covers a cleaned glass substrate 10, and the substrate 10 is heated to 200 - 5000C in a vacuum chamber of 5 x 10-7 torr, and then an argon (Ar) gas is injected and a material from the group consisting of TaAl, Ni-Cr alloy, SnO2, HfB2 and Ta is coated through PVD or CVD, to form a unit heating layer 20. At this time, the surface area and the thickness of the unit heating layer 20 can be controlled according to a desired electric resistance value.
Then, a metal mask (not shown) for forming an electrode covers the substrate 10 where the heating layer 20 is formed, and a material selected from the group consisting of Al, Au, Ag, RuO2 and Pt having good electrical conductivity is coated on the resultant in a vacuum chamber through PVD or CVD, to form an electrode layer 30 as shown in Figure 3B. At this time, the surface area and the thickness of the coated electrode layer 30 can be appropriately controlled according to the desired electric resistance value.
As shown in Figure 3C, a protective layer 40 for protecting the unit heating layer 20 and the electrode layer 30 is formed. That is, a metal mask (not shown) for forming a protective layer covers the substrate 10 where the heating layer 20 and the electrode layer 30 are formed and a material selected from the group consisting of Si3N4,SiO2 and SiC is coated in a vacuum chamber through PVD orCVD. At this time, preferably, the protective layer 40 is coated to have a predetermined thickness along the upper surface line of the unit heating layer 20 and the electrode layer 30.
According to the thin film type heater of embodiments of the present invention, a material having good electric resistance is adopted so that the initial heating time is short. Also, a small heater can be manufactured by thinfilm coating so that the heater can be uniformly formed on, for example, the entire inner surface of the water tank, to thereby maximize the instantaneous heating efficiency.
The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.