JPH05283146A - Thick film resistance heating element - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a thick film resistance heating element in which lead wires are securely connected electrically and mechanically. A thick film resistance heating element of the present invention comprises a pair of a substrate, a thick film resistor layer formed on the surface of the substrate, and metal pieces connected to both ends of the thick film resistor layer. An electrode terminal and a pair of lead wires for electrically connecting the external power source and the pair of electrode terminals are provided, and each electrode terminal and the current-carrying end of the electric resistor layer are electrically connected by a conductive adhesive. It is characterized in that it is mechanically fixed with a non-conductive adhesive having a fixing strength higher than that of the conductive adhesive. According to the thick film resistance heating element of the present invention, the electrode terminal firmly connected to the lead wire is electrically connected to the thick film resistor layer with the conductive adhesive, and the non-conductive adhesive having a strong adhesive force is used. They are mechanically and firmly connected with an agent. Since the purpose and function are separated by the conductive adhesive and the non-conductive adhesive,
Strong and reliable electrical and mechanical connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing heater used for toner fixing of a copying machine.

[0002]

2. Description of the Related Art In recent years, as a thick film resistance heating element used for toner fixing of an electronic copying machine, a long thin line-shaped heater is formed by applying a paste of silver / palladium alloy powder or the like on the surface of an insulating substrate such as a long thin ceramic. The thick-film resistance heating element is used in practice. A voltage is applied to both ends of the line-shaped thick film resistance heating element to heat the thick film resistance heating element to fix the toner.

[0003]

This thick film resistance heating element is provided with a special socket for connection with the power supply circuit.
An elastic metal piece such as a clip is used for conducting contact with the substrate. In this case, the power circuit and the socket are connected by a lead wire, but the heater itself is not connected by a lead wire.

However, such a special-purpose socket is an obstacle to cost reduction, and therefore, attempts have been made to connect the lead wire directly to the heater. In this case, a large current of up to 12 A instantaneously flows through the fixing heater. Therefore, when the lead wire is soldered to the thick film resistance heating element like an ordinary electric circuit, the solder is oxidatively deteriorated and the joint is peeled off. There is a risk of an electric leakage accident. Further, when the lead wire is welded to the thick film resistance heating element, the thick film resistor layer is melted, which causes a problem that a reliable connection cannot be made.

Therefore, it is an object of the present invention to provide a thick film resistance heating element in which lead wires are securely connected electrically and mechanically.

[0006]

In order to achieve the above object, a thick film resistance heating element according to any one of claims 1 to 5 comprises a substrate and a thick film resistor layer formed on the surface of the substrate. A pair of electrode terminals made of metal pieces connected to both ends of the current-carrying portion of the thick film resistor layer, and a pair of lead wires electrically connecting the external power source and the pair of electrode terminals, The electrode terminals and the current-carrying end of the electric resistance layer are electrically connected with a conductive adhesive, and are mechanically fixed with a non-conductive adhesive that has a stronger fixing strength than the conductive adhesive. And

[0007]

In the thick film resistance heating element of the present invention, the electrode terminals firmly connected to the lead wires are electrically connected to the thick film resistor layer with the conductive adhesive, and the non-conductive adhesive having a strong adhesive force is used. They are mechanically and firmly connected with an agent. Since the purpose and function are separated by the conductive adhesive and the non-conductive adhesive, the electrical and mechanical connection can be made firmly and surely.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view of a thick film resistance heating element of the first embodiment, FIG. 2 is a partial sectional view taken along the line AA in FIG.
3 is a perspective view of the electrode terminal, FIG. 4 is a perspective view showing a connection state of the electrode terminal and the lead wire, and FIG. 5 is a cross-sectional view taken along the line BB in FIG. The board (1) is a long flat plate (about 270 mm x 7 mm x
Alumina ceramics (size of about 1 mm) (Al2O
It consists of 3). A band-shaped thick film resistor layer (3) is formed on the surface of the substrate (1). The thick film resistor layer (3) is a conductive paste-like paint (made of silver-palladium alloy (Ag
/ Pd) or a metal obtained by adding ruthenium oxide thereto (A
g / Pd + RuO2)) is screen-printed / applied on the substrate (1) and then baked to a thickness of about 10 μm.
It was formed in. Palladium contained in this alloy serves as an electric resistance element, and the resistivity is adjusted by the ratio. In this embodiment, the resistance value is 34 Ω [Ω], and the current of 3 A flows when the voltage of 100 V is applied.
The heating value is 300 W. Both ends of the thick film resistor layer (3) are formed wide so as to form an electrode layer connecting portion (5).
The strip-shaped part of the thick film resistor layer (3) excluding the electrode layer connecting part (5) generates heat.

The surface of the electrode layer connecting portion (5) at both ends of the thick film resistor layer (3) and the exposed substrate (1) of the substrate (1) on which the thick film resistor layer (3) is not formed. ) Electrode layers (7) for connecting to external electrode terminals (11) are respectively formed on both end surfaces. FIG. 2 shows only one of them, but the other has the same structure. This electrode layer (7) is provided in order to make contact electric resistance smaller than that of the thick film resistor layer (3), and is made of silver (Ag), silver-platinum alloy (Ag / Pt), gold (A).
u), platinum (Pt) or other metal paste is used. That is, after the thick film resistor layer (3) including the electrode layer connecting portion (5) is formed (after the resistance heating element paste is applied by printing and firing), these metal pastes are applied to the electrode layer connecting portion (5). The substrate (1) on which the upper and thick film resistor layers (3) are not exposed is screen-printed / applied on the surfaces of both ends of the substrate (1), and then baked to obtain a thickness of 3 ~.
The electrode layer (7) is formed to a thickness of about 5 μm.

The surface of the strip-shaped portion of the thick film resistor layer (3) is coated with glass having a high electric insulation property to form an insulating glass coating layer (9). This insulating glass coating layer (9) is mainly composed of borosilicate glass, for example, an insulating glass paste PLS3310 manufactured by Nippon Electric Glass Co., Ltd. is applied by screen printing,
After that, it is baked to have a thickness of about 10 μm.
The insulating glass using PLS3310 has an electric breakdown voltage of 2000 under the condition of applying a DC voltage when the thickness is 35 μm.
Have V. The insulating glass paste PLS3310 is applied by printing and baked after the thick film resistor layer (3) is formed.

The insulating glass coating layer (9) is applied not only to the strip portion of the thick film resistor layer (3) but also to the boundary portion of the electrode layer (7). This is because the temperature gradient near the boundary between the strip-shaped portion of the thick film resistor layer (3) and the electrode layer connecting portion (5) is steep, so that the thick film resistor layer (3) near this may be broken. Although high, this risk is reduced by covering this part with an insulating glass coating layer (9). Further, in the vicinity of the boundary of the electrode layer (7) (in FIG. 1, the solid line a indicates the electrode layer (7)).
(Representing the boundary of) is easily peeled off due to the effect of heat generation, but by covering this part with the insulating glass coating layer (9), this risk is also reduced. In FIG. 1, the broken line b and the broken line c mean the boundary line of the insulating glass coating layer (9) and the boundary line of the thick film resistor layer (3), respectively.

The electrode terminal (11) is fixed to the region where the electrode layer (7) is directly formed on the substrate (1) by an adhesive. The electrode terminal (11) has a rectangular metal flat plate portion (11a) and a U-shaped lead wire holding claw portion (11b).
The lead wire holding claw portion (11b) is welded to the metal flat plate portion (11a) in advance. The electrode terminal (11) is formed of, for example, a nickel plate or the like. Before the electrode terminal (11) is connected to the electrode layer (7), the lead wire (13) connected to the power supply circuit (not shown) is clamped and fixed to the lead wire clamping claw portion (11b). Lead wire (1
The part of 3) clamped and fixed to the lead wire clamping claw part (11b) is welded and fixed to the lead wire clamping claw part (11b), and the other parts are insulated and coated.

The electrode terminal (11) to which the lead wire (13) is previously connected as described above is connected and fixed to the electrode layer (7) with an adhesive. The adhesive is composed of a conductive adhesive (15) having a function of electrical conduction and temporary fixing, and a non-electrically conductive adhesive (17) which is non-conductive but has a stronger adhesive strength than the conductive adhesive (15). Two types are used. Conductive adhesive (15)
Is 8 on the back surface of the metal flat plate portion (11a) of the electrode terminal (11).
It is applied in a split manner to form an electrically conductive portion with the electrode layer (7). By making 80% of the back surface a conductive adhesive (15), the electric resistance of the electrode terminal (11) and the electrode layer (7) can be reduced. The non-electrical adhesive (17) is applied to the remaining portion of the back surface of the metal flat plate portion (11a), that is, 20%, to contribute to the mechanical connection with the electrode layer (7), and also to the metal flat plate portion ( It is also applied to the surface of 11a) and the lead wire (13)) is also fixed at the same time. Non-electrical adhesive (1
7) has a stronger adhesive force than the conductive adhesive (15), and can securely fix the electrode terminal (11).

The conductive adhesive (15) is, for example, an epoxy resin based on which silver powder is dispersed. For example, the conductive adhesive FA-7 manufactured by Fujikura Kasei Co., Ltd.
There are 07 and so on. Further, the non-electric adhesive (17) contains
For example, an epoxy resin adhesive EP manufactured by Cemedine Co., Ltd.
There is -106.

In the resistance heating element having the above structure, the electrode terminal firmly connected to the lead wire is electrically connected to the thick film resistor layer (3) with the conductive adhesive (15), and the adhesive force is high. Since the strong non-conductive adhesive (17) is mechanically and firmly connected, the conductive adhesive (15) and the non-conductive adhesive (17) are separated from each other in purpose and function. Strong and reliable electrical and mechanical connection. In particular, since the lead wire is also fixed to the non-conductive adhesive (17), peeling and dropping of the electrode terminal (11) due to pulling of the lead wire (13), which is the main cause, can be prevented.

The present invention is not limited to the above embodiment. For example, as shown in FIG. 6, the electrode layer connecting portion (5) may be printed and formed up to the end of the substrate (1), and the electrode layer (7) may be formed on the electrode layer connecting portion (5). .. In this case, Ag molecules in the electrode layer (7) tend to diffuse into the thick film resistor layer (3), which may increase the resistance value of the electrode layer (7) and generate heat. Therefore, it is preferable to shift the electrode layer (7) from the electrode layer connecting portion (5) as in the first embodiment. That is, when the influence of this heat generation is small, even if the electrode layer (7) is formed on the electrode layer connecting portion (5), the harmful effect is small.

The present invention can be modified in various ways. For example, if the uncoated portion at the tip of the lead wire has a sufficiently large area and can be connected to the electrode layer (7) through the conductive adhesive (15) as an electrode terminal without requiring a special member, the present invention is Applicable. In this case, a non-conductive adhesive agent (17) is applied to the portion following the tip of the lead wire to strengthen the fixation of the tip of the lead wire and the electrode layer. The tip of the lead wire and the portion following it also serve as electrode terminals.

Further, in each of the above-mentioned two embodiments, various thick film layers and electrode terminals are formed on only one side of the substrate, but both sides may be used, and electrode terminals are formed on both ends of the substrate. However, it is not limited to 2
It may be formed with one electrode terminal. Further, the present invention is applicable to a resistance heating element in which the thick film resistor layer (3) is branched near the center of the substrate, and as a result, a plurality of electrode terminals are arranged side by side on one surface.

Further, the present invention is not limited to the substrate (1) made of ceramic, and a synthetic resin member having high heat resistance such as metal or polyimide resin can be used.
When using a metal, it goes without saying that an insulating underlayer is required between the metal and the thick film resistor layer. Further, the shape is not limited to the flat plate. Further, the heating portion of the thick film resistor layer (3) does not need to be a straight line, and the application can be applied to other than the fixing heater.

Further, the structure of the electrode terminal (11) is not limited to the above embodiment. The present invention is applicable to the case where the adhesive can be used even if the electrode terminal is not a flat plate. Also,
The lead wire (13) and the electrode terminal (11) are not limited to being connected by welding, but may be simply caulked, and conversely, they are not caulked as in the above embodiment, and are welded. It may be fixed only.

[0021]

According to the thick film resistance heating element of the present invention having the above-mentioned structure, the electrode terminal firmly connected to the lead wire is electrically connected to the thick film resistor layer by the conductive adhesive. In addition, they are mechanically and firmly connected with a non-conductive adhesive having a strong adhesive force. Since the purpose and function are separated by the conductive adhesive and the non-conductive adhesive, the electrical and mechanical connection can be made firmly and surely.

[Brief description of drawings]

FIG. 1 is a plan view of a resistance heating element according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view taken along the line AA in FIG.

FIG. 3 is a perspective view of an electrode terminal used in the first embodiment.

FIG. 4 is a perspective view showing a state in which lead wires are connected to the electrode terminals shown in FIG.

5 is a sectional view taken along line BB in FIG.

FIG. 6 is a view of a resistance heating element according to a second embodiment of the present invention.
Partial sectional view corresponding to

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 3 ... Thick film resistor layer, 5 ... Electrode layer connection part 7 ... Electrode layer, 9 ... Insulating glass coating layer, 11
... Electrode terminal 13 ... Lead wire, 15 ... Conductive adhesive 17 ... Nonconductive adhesive

Claims (5)

[Claims] 1. A substrate, a thick film resistor layer formed on the surface of the substrate, a pair of electrode terminals connected to both ends of current-carrying parts of the thick film resistor layer, an external power source and the pair of electrode terminals. And a pair of lead wires for electrically connecting with each other, each electrode terminal and the end of the current-carrying portion of the electric resistance layer are electrically connected with a conductive adhesive, and have a stronger fixing strength than the conductive adhesive. A thick film resistance heating element characterized by being mechanically fixed with a non-conductive adhesive. 2. The thick film resistance heating element according to claim 1, wherein the electrode terminal and the lead wire are welded to each other. 3. The thick film resistor according to claim 1, wherein a good conductor layer having a resistivity lower than that of the thick film resistor layer is formed between the conductive adhesive and the thick film resistor layer. Heating element. 4. The thick film resistance heating element according to claim 1, wherein the non-conductive adhesive fixes a part of the lead wire. 5. The thick film resistance heating element according to claim 1, wherein the tip of the lead wire also serves as an electrode terminal.