EP1547113B1 - Self-configuring component by means of arcing - Google Patents

Abstract

The component (1) has an internal conductor train (3) that is separated at a defined point (4) with the formation of a spark if defined current/voltage conditions occur at component connections (6,7). A circuit element (8) is arranged in the component so that a spark produced at the defined point can act upon the circuit element so as to change its electrical properties.

Description

The invention relates to a device with an internal conductor, which is designed so that it is cut at a predetermined location to form an arc, provided that predetermined current / voltage conditions occur at terminals of the device. Such devices are e.g. from document US 5 148 141 known.

A component of the type mentioned is, for example, a fuse element in the embodiment as a chip fuse. If the current flow through the chip fuse exceeds a maximum value for a predetermined duration, it may turn off the fuse, i. come to a cutting of a fuse conductor. Starting at the point of separation, an arc is formed in the fuse component, which allows a continued flow of current between the terminals of the chip fuse despite the severed fusible conductor. The arc and the continued current flow are undesirable. In particular, in the event of a short circuit, undesired destruction of the fuse component and the surrounding circuit may occur in the case of very high currents transported via the arc. Therefore, at least a limitation of the current flowing in the event of a short circuit when switching off via the arc current is desired. Such a current limitation could be realized, for example, by a resistor connected in series with the fuse component. Such a series resistor would be disturbing in the normal operating case with intact fuse, because the lowest possible resistance of the fuse component is desired.

The object of the invention is therefore to provide a device with which a fuse component can be produced, in which a reduced current flow in the case of shutdown is possible without adversely affecting the operating parameters during normal operation (before shutdown).

This object is achieved in a device of the type mentioned above in that in the device a circuit element is arranged so that an arc generated at the predetermined location can act on the circuit element such that the circuit element thereby changes its electrical properties.

The core idea of the invention is to utilize the energy released when switching off the arc in such a way that the electrical properties of a circuit element of a component are changed in a desired manner, ie the component is reconfigured. From the documents DE 199 57 423 and DE 197 35 552 fuses are known, which with the help of an external arc parts of a component to configure. In the simplest case, the component can be a two-terminal coil with two terminals, wherein the change in the electrical properties of the circuit element caused by the arc leads to an altered two-pole behavior of the component. In an alternative embodiment (not further discussed below), the internal conductor trace severed by the arc and the circuit element whose electrical characteristics are changed could be connected to separate terminals of the device.

In a preferred embodiment, the device is a layer device in which the conductor and the circuit element of structured layers are formed on a substrate. For example, these are thick-film conductive layers and resistor layers.

For example, the circuit element reconfigured by the arc may be any two-terminal. In one embodiment, this two pole changes its electrical resistance upon the action of the arc; Preferably, the resistance is increased. In another preferred embodiment, the circuit element is a second conductor, which is severed when exposed to the arc. In this embodiment, so to speak, first the internal Conductor divided to form the arc and then cut as a result of this arc, the second conductor also. In order to enable an energetically favorable action of the arc on the second conductor, the second conductor preferably crosses the internal conductor at the predetermined location at which the internal conductor is severed to form the arc.

A preferred embodiment of the device is characterized in that in the device parallel to the second conductor, on which the arc can act, a resistance element is connected. The parallel circuit thus formed has a very low resistance before the action of the arc and, after the action of the arc, the resistance of the resistance element alone. Preferably, this parallel circuit of circuit element and resistive element is connected in series with the internal circuit trace which is severed to form the arc. This series connection has a very low resistance before the formation of an arc, namely the series connection of the internal Leiterzugs and the second Leiterzugs. Under predetermined current / voltage conditions at the terminals of the device, for example, when a high current flows, the internal Leiterzug is severed to form the arc. In this case, the second conductor is also severed. As a result, the resistive element is connected in series with the still existing arc of the internal circuit trace. The resistive element then limits the current flow through the arc.

The latter embodiment is preferably used as a fuse component, wherein the internal conductor is severed to form an arc, as long as a current through the conductor exceeds a maximum value for an associated maximum duration. A "cut-off" (cut-through) can be carried out at different currents, wherein at higher current values, a lower Stromflußdauer to to shut down is required. Such a fuse component has the advantage that in the case of switching off with a resulting arc, a resistor is connected in the current path. The resistance (ie the resistance element) must be designed taking into account the power loss so that the short-circuit current is limited to a fraction which causes a much lower stress on the device and the surrounding circuit.

In a preferred embodiment, the resistor element connected in parallel with the second conductor has a resistance between 5Ω and 20Ω. The dimensioning of the resistance element, both in terms of the ohmic resistance and its maximum power loss depends on the application of the fuse component, in particular from the cut-off and the maximum applied voltage.

In a preferred embodiment of the fuse component, the internal and the second conductor line and the resistance element are formed from structured layers on a substrate, wherein the internal conductor line is arranged over a portion of the second conductor line and separated therefrom by an electrically insulating layer. For example, the internal conductor trajectory crosses the second conductor traction covered by an insulator layer.

Advantageous and preferred developments of the invention are characterized in the subclaims.

• Figur 1A eine schematische Darstellung der wesentlichen Elemente des Layouts eines erfindungsgemäßen Sicherungsbauelements in normalen Betrieb;
• Figur 1B ein Schaltbild des Sicherungsbauelements gemäß Figur 1A;
• Figur 2A eine schematische Darstellung der wesentlichen Elemente des Layouts des Sicherungsbauelements gemäß Figur 1A nach der Ausbildung eines Lichtbogens beim Durchtrennen des Sicherungsbauelements; und
• Figur 2B ein Prinzipschaltbild des Sicherungsbauelements gemäß Figur 2A nach Ausbildung des Lichtbogens.

In the following the invention will be described with reference to a preferred embodiment shown in the drawing. In the drawing show:

• Figure 1A is a schematic representation of the essential elements of the layout of a fuse component according to the invention in normal operation;
• FIG. 1B is a circuit diagram of the fuse component according to FIG. 1A;
• Figure 2A is a schematic representation of the essential elements of the layout of the fuse component according to Figure 1A after the formation of an arc during cutting of the fuse device; and
• FIG. 2B shows a block diagram of the fuse component according to FIG. 2A after the arc has been formed.

FIG. 1A shows a schematic plan view of the upper side of a component 1. On the upper side of a substrate 2, for example an Al ₂ O ₃ substrate or another ceramic substrate, a number of layers (preferably in thick-film technology) are applied. Figure 1A illustrates only the layers essential to the invention. In addition to the illustrated layers, a number of further layers may be applied below, between or over the illustrated layers, for example insulator, capping, protective layers and layers which influence heat dissipation. On the substrate 2, a first conductive layer 5 is first applied and patterned, which in addition to the pads 6 and 7 comprises a transverse to the longitudinal direction of the substrate 2 extending conductor 8. The conductor 8 is part of a U-shaped Leiterzugschleife in the conductive layer 5. About the conductive layer 5, a resistance layer 9 is applied, which is structured so that an approximately rectangular portion of the resistance layer, the legs of the U-shaped Leiterzugschleife at the upper ends combines. That is, between the conductive layer 5 and the resistance layer 9, an electrical contact is made. In an alternative embodiment, the resistive layer 9 could also be disposed under the conductive layer 5. This arrangement of the patterned resistive layer 9 and the structured conductive layer 5 creates a parallel connection between a resistor and a U-shaped conductor loop, wherein one terminal of the parallel circuit is connected directly to the contact surface 6.

An electrically insulating layer (not shown in FIG. 1 a) is applied over the conductive layer 5 and at least one further structured conductive layer 3 is applied to this insulator layer. The further conductive layer 3 is structured so that it forms a Leiterzugstreifen which overlaps the contact surface 7 at one end and overlaps at its other end the U-shaped Leiterzug. In both overlapping regions, a window is formed in the insulator layer arranged between the conductive layer 5 and the at least one further conductive layer 3, so that contacts can be produced between the conductive layer 5 and the conductive layer 3 at these locations. The contact of the conductive layer 3 to the underlying conductive layer 5 in the U-shaped Leiterzugbereich is located at that end of the U-shaped Leiterzugschleife that forms not connected to the contact surface 6 node of the parallel circuit of resistance layer 9 and U-shaped Leitzugschleife. In addition, a section 4 of the at least one further conductive layer 3 crosses the conductor 8. The section 4 of the conductive layer 3 crossing the conductor 8 is separated from the conductor 8 by the insulator layer. In addition, the portion 4 of the at least one conductive layer 3 is formed as a fusible element, for example (as shown in Figure 1A) of smaller width than the rest of the conductor formed in the conductive layer 3 Leiterzugs. The fusible element forming portion 4 in the at least one conductive layer 3 may include, for example, a thick-film conductor containing silver and, in addition, a solder layer deposited thereon.

FIG. 1B shows a circuit diagram of the arrangement shown schematically in FIG. 1A. The contact surfaces 6 and 7 correspond to the terminals 16 and 17, respectively. The U-shaped conductor loop in the conductive layer 5 corresponds to the short-circuit connection 18. The resistance element formed in the resistance layer 9 corresponds to the resistor R 19. The fusible conductor element formed in the at least one second conductive layer 3 in the section 4 corresponds to the fusible conductor element 14 in FIG. 1B.

In normal operation, in which the currents flowing through the device 1 are sufficiently small so that the fuse element 14 remains intact, the current flows essentially through the short-circuit connection 18 and the fuse element 14 between the terminals 16 and 17. The device 1 has a small ohmic resistance.

If the current flow through the device 1 exceeds a certain current for a predetermined period of time, the fusible conductor element 14, ie the section 4 in the conductive layer 3, is severed. The process of severing (switching off) depends on the structure of the fusible element. For example, if a conductive layer 3 containing silver particles is covered at a predetermined location by a solder layer (containing tin and lead), and if the current flowing causes the device to be heated, the conductive layer is severed due to a complex process associated with melting of the device Lotimetalls, the diffusion of the metal into the silver layer, the increase in the resistivity of the conductive layer, the local heating and the evaporation of the conductive layer is accompanied. In other cases where the fusible element contains only one conductive layer, the process of severing is primarily determined by evaporation of the conductive layer material due to local heating. In any case, there is a local separation of the conductive layer 3 in section 4, which forms an arc at the separation point, with the aid of a continuous flow of current is made possible with severed interconnect. The arc causes further vaporization of the located at the two ends of the arc Leitschichtbereiche the layer 3, wherein the remaining ends of the conductive layer, between where the arc is formed, further from each other, whereby the arc lengthens.

FIGS. 2A and 2B schematically show the fuse component 1 shown in FIG. 1A and the circuit shown in FIG. 1B in the case where an arc 10 has formed in the region of the severed portion 4 of the conductive layer. As the arc 10 vaporizes the material of the section 4, the energy of the arc simultaneously evaporates the material of the underlying insulator layer and a portion of the underlayer material of the conductive layer 5 in the circuit trace 8. By the action of the arc 10, the circuit trace 8 becomes finally severed. The thickness of the insulator layer between the conductive layer 3 and conductive layer 5 in the region of Leiterzugs 8 must be chosen so that on the one hand provides sufficient electrical insulation available, on the other hand is as thin as possible to a high proportion of the arc energy to the conductive layer. 5 allow the conductor 8. In addition, the combination of conductive layer 5 (in Leiterzugbereich 8) and insulator layer must be designed so that an ignition of an arc between the connected to the terminal 6 portion of the broken Leiterzugs 8 and connected to the terminal 7 portion of the conductive layer 3 is avoided. This can be achieved by a suitable layout design and insulator layer thickness.

Figure 2B shows the circuit diagram that results when the arc 10 is ignited and the conductor 8 is already severed. The resistor 19 connected in parallel short-circuit connection 18 is cut, so that between the terminals 16 and 17, the resistor R19 is connected in series with the arc 10. The resistor R thus limits the current flowing across the arc 10 current. The dimensioning of the resistor 19, both in terms of resulting ohmic resistance R as well as in terms of power consumption (maximum power dissipation) depends on several factors, which depend on the maximum voltage between the contacts 16 and 17 and the desired maximum current (short-circuit current). In one embodiment, R could have a resistance between 5Ω and 20Ω, for example 10Ω.

Numerous alternative embodiments are conceivable within the scope of the inventive concept.

When the component is used as a fuse component, the layout shown in FIG. 1A (with the same circuit diagram) could be considerably modified. The order of the layer application could also be changed. For example, the conductor 8 could be arranged parallel to the section 4 of the conductor 3 or 3 cross the section 4 twice in a U-shaped course of the conductor. In an alternative embodiment, the energy of the arc could also be used to modify a layer deposited on the substrate 2 without vaporizing it. For example, the action of the arc could cause an increase in the sheet resistance, for example by alloying effects.

Claims (12)

1. A component (1) with an internal conductor (3), which is so configured that it is ruptured at a predetermined position (4) whilst forming an arc (10) if predetermined current/voltage conditions occur at the terminals (6, 7) of the component (1), characterised in that a circuit element (8) is so arranged in the component (1) that an arc (10) formed at the predetermined position (4) can act on the circuit element (8) such that the circuit element (8) alters its electrical properties.
2. A component as claimed in claim 1, characterised in that the component (1) is a layered component, the conductor (3) and the circuit element (8) being constituted by structured layers on a substrate (2).
3. A component as claimed in claim 1 or 2, characterised in that the component (1) has two terminals (6, 7) and that the internal conductor (3) and the circuit element (8) are connected between the two terminals (6, 7).
4. A component as claimed in one of claims 1-3, characterised in that the circuit element is a two-pole component, which alters its electrical resistance under the action of the arc.
5. A component as claimed in one of claims 1-3 characterised in that the circuit element is a second conductor (8), which is ruptured under the action of the arc (10).
6. A component as claimed in claim 5, characterised in that the second conductor (8) crosses the internal conductor (3) at the predetermined position (4).
7. A component as claimed in claim 5 or 6, characterised in that a resistive element (9) is connected in the component (1) in parallel with the second conductor (8), on which the arc (10) can act.
8. A component as claimed in claim 7, characterised in that the internal conductor (3), which is ruptured to form an arc (10), is connected in series with the parallel circuit comprising the circuit element (8) and resistive element (9).
9. A component as claimed in claim 8 for use as a fuse component, characterised in that the internal conductor (3) is ruptured to form an arc (10) if a current through the conductor exceeds a maximum value for an associated maximum period of time.
10. A component as claimed in claim 9, characterised in that the resistive element (9), which is connected in parallel with the second conductor, has a resistance between 5Ω and 20Ω.
11. A component as claimed in claim 9 or 10, characterised in that the internal conductor (3) includes a fusible conductor.
12. A component as claimed in one of claims 9 to 11, characterised in that the internal conductor (3) and the second conductor (8) and the resistive element (9) are constituted by structured layers on a substrate (2), the internal conductor (3) being arranged above a section of the second conductor (8) and separated from it by an electrically insulating layer.

Images