DE102019128903A1 - Connecting a connecting wire to a contacting element of a device - Google Patents

Abstract

The invention comprises a device (1) for detecting a physical measured variable of a measurement medium, comprising: - a substrate (100); - a sensor element (110) applied to a first partial area of the substrate (100); - a sensor element (110) applied to a second partial area of the substrate (100) applied contact pad (120), the contact pad (120) being connected to the sensor element (110) by means of at least one conductor track; - a contacting element which has a connection surface (130) and which is applied to the contact pad (120); and a connection wire (140) which has a connection surface (130 ') on one end region, the connection surface (130) of the contacting element having a plurality of nanowires and / or the connection surface (130') of the connection wire (140) having a plurality of nanowires, the connection surface (130) of the contacting element and the connection surface (130 ') of the connection wire (140) being brought together in such a way that they contact one another by means of the nanowires, as well as a method for connecting a connection wire (140) to a contacting element of a device according to the invention (1).

Description

The invention relates to a device for acquiring a physical measured variable of a measuring medium. Furthermore, the invention relates to a method for connecting a connection wire, which has a connection surface, to a contacting element of a device, which has a connection surface, wherein the device comprises a substrate, a sensor element applied to a first partial area of the substrate, a sensor element applied to a second partial area of the Has a contact pad applied to the substrate and a contacting element applied to the contact pad, the contact pad being connected to the sensor element by means of at least one conductor track.

A large number of sensor elements for determining physical measured values of various measurement media are known from the prior art. For example, they are used to determine the temperature, the gas concentration, the flow rate, the moisture content or the pH value of the measuring medium.

Standard sensor elements are typically constructed in such a way that they are designed as a, in particular structured, layer and are applied to a substrate. The sensor element itself is connected to a contact pad by means of a conductor track. Typically, a short connecting wire is welded or soldered to the contact pad. This complete package is delivered to the customer, who then has to extend the connecting wire in a suitable manner in order to install the sensor element in his application or in his product.

• Die Anschlussdrähte müssen herstellerseitig oft einzeln pro Sensorelement angeschweißt oder angelötet werden, was zeitaufwendig und teuer ist. Kundenseitig müssen zudem die Anschlussdrähte jedes Sensors einzeln verlängert werden (beispielsweise mittels Laserschweißens, Lötens und/oder Krimpens), was ebenfalls zeitaufwändig ist. Zudem verlangt dies spezielles Equipment und Know-How beim Kunden. Weiterhin besteht die Gefahr, das Sensorelement thermisch zu schädigen oder zu „vergiften“, beispielsweise durch inkompatibles Flussmittel. Je nach Prozess weist die Verbindung des Anschlussdrahtes mit dem Kontaktpad zudem nur eine geringe bis mittelmäßige Temperaturbeständigkeit auf.

This structure has various disadvantages:

• The connection wires often have to be welded or soldered individually to each sensor element by the manufacturer, which is time-consuming and expensive. On the customer side, the connecting wires of each sensor must also be individually extended (for example by means of laser welding, soldering and / or crimping), which is also time-consuming. In addition, this requires special equipment and know-how from the customer. There is also the risk of thermally damaging or “poisoning” the sensor element, for example through incompatible flux. Depending on the process, the connection between the connecting wire and the contact pad also has only a low to mediocre temperature resistance.

The object of the present invention is therefore to provide a thermally stable electrical connection between a connecting wire and a sensor element, which can be implemented without special equipment and know-how.

The object is achieved by a device according to claim 1 and by a method according to claim 10.

• - Ein Substrat;
• - Ein auf einem ersten Teilbereich des Substrats aufgebrachtes Sensorelement;
• - Ein auf einem zweiten Teilbereich des Substrats aufgebrachtes Kontaktpad, wobei das Kontaktpad mittels zumindest einer Leiterbahn mit dem Sensorelement verbunden ist;
• - Ein Kontaktierungselement, welches eine Anschlussfläche aufweist und welches auf dem Kontaktpad aufgebracht ist; und
• - Ein Anschlussdraht, welcher auf einem Endbereich eine Anschlussfläche aufweist, wobei die Anschlussfläche des Kontaktierungselement eine Vielzahl von Nanodrähten aufweist und/oder wobei die Anschlussfläche des Anschlussdrahts eine Vielzahl von Nanodrähten aufweist,

wobei die Anschlussfläche des Kontaktierungselements und die Anschlussfläche des Anschlussdrahts derart zusammengeführt sind, dass sich diese mittels der Nanodrähte kontaktieren.With regard to the device for detecting a physical measured variable of a measurement medium, it is provided that the device comprises:

• - a substrate;
• - A sensor element applied to a first partial area of the substrate;
• A contact pad applied to a second partial area of the substrate, the contact pad being connected to the sensor element by means of at least one conductor track;
• A contacting element which has a connection surface and which is applied to the contact pad; and
• A connection wire which has a connection surface on one end region, the connection surface of the contact-making element having a multiplicity of nanowires and / or the connection surface of the connection wire having a multiplicity of nanowires,

wherein the connection surface of the contacting element and the connection surface of the connection wire are brought together in such a way that they contact one another by means of the nanowires.

By using nanowires on at least one of the connection surfaces, an electrically conductive and mechanically stable connection can be created.

Depending on the material, the connection is resistant up to high temperature ranges, in particular up to 1500 ° C.

Both connection surfaces, that is to say that of the contacting element and that of the connection wire, preferably have nanowires. In such a case, the connection between the connecting wire and the contacting element can be designed to be particularly electrically conductive and mechanically stable, since the surface area of the connection is increased due to the size of the nanowires.

The connecting wire is, in particular, wire with a circular cross section. Alternatively, it can also be a flat wire or leadframe. The connecting wire can preferably consist of platinum, Pt DPH, nickel, gold, a platinum-nickel alloy, a gold-nickel alloy or copper.

In connection with the invention, the feature “sensor element” denotes a sensitive or active layer, which is structured, for example.

According to a first variant of the device according to the invention, it is provided that in the event that the contacting element has nanowires, the contacting element has at least one adhesive layer, the adhesive layer being applied in the area of the contact pad or on the contact pad, and the connection surface being on the adhesive layer is upset. The adhesive layer serves to adhere the nanowires to the contact pad or to the surface which is provided for applying the nanowires. It can be provided that the connection surface of the connection wire is also provided with such an adhesive layer. The adhesive layer advantageously comprises titanium-tungsten alloy, chromium-platinum, nickel-chromium or other typical adhesive layers. A plurality of adhesive layers of different materials superimposed on one another can also be provided.

According to a second variant of the device according to the invention, it is provided that, in the event that the contacting element is free of nanowires, the contacting element has a layer with a rough or porous surface applied to the contact pad. As a result, the surface of the contact pad is enlarged, as a result of which the adhesion of the nanowires to the connection surface of the connection wire is increased.

According to an advantageous embodiment of the first or the second variant, a cover layer is provided which completely or partially covers the contact-making element and the end region of the connection wire. This increases the strength of the connection between the connection surface of the connection wire and the connection surface of the contact-making element, in particular if only one of these two connection surfaces has nanowires. The cover layer preferably consists of a glass, a glass ceramic or a polymer.

According to a third variant of the device according to the invention, it is provided that the contacting element comprises a wire element with a first and a second end region, the first end region being connected to the contact pad and the connection surface being arranged on the second end region. In this variant, the device already has a short connecting wire, referred to as a “wire element”. This can be attached to the contact pad by soldering or welding. It can also be provided, as described with respect to the first and the second variant, to reinforce this soldered or welded connection by means of a cover layer. This wire element has a connection surface to which the connection wire can be connected by means of nanowires in order to lengthen the wire element. This eliminates the need associated with the sensor elements known from the prior art to lengthen the wire element in a costly manner by means of laser welding, soldering and / or crimping.

According to an advantageous embodiment of the device according to the invention, it is provided that the nanowires are attached to one side of the respective connection surface and essentially cover the respective connection surface over a large area. The respective connection surface thus has a flat covering with nanowires, that is to say is completely covered with the nanowires, which form a nanoscale.

According to an advantageous embodiment of the device according to the invention, it is provided that the nanowires consist of a metal, in particular copper, silver, gold, nickel or platinum. Alternatively, the nanowires consist of an alloy which comprises at least one of the aforementioned metals. In this way, an electrically conductive connection between the contact pad and the connecting wire can be ensured.

According to an advantageous embodiment of the device according to the invention, it is provided that the nanowires are produced by means of an ion track etching process. The nanowires preferably have a length in the range from 100 nm to 100 μm. Furthermore, the nanowires preferably have a diameter in the range from 10 nm to 100 μm, in particular in the range from 30 nm to 2 μm. The term “diameter” refers to a circular base area, with a comparable definition of a diameter being used for a base area that differs therefrom. It is particularly preferred that all nanowires used have the same length and the same diameter. Alternatively, the wires can also be manufactured using other, suitable manufacturing methods.

According to an advantageous embodiment of the device according to the invention, it is provided that the sensor element is a temperature sensor, a gas sensor, a flow sensor, a humidity sensor, a conductivity sensor, a pH sensor or a biosensor, or the sensor element is designed to react with an electrical Power to emit heat.

• - Bereitstellen einer Vielzahl von Nanodrähten auf der Anschlussfläche des Kontaktierungselements und/oder Bereitstellen einer Vielzahl von Nanodrähten auf der Anschlussfläche des Anschlussdrahts;
• - Zusammenführen der Anschlussflächen, so dass die Anschlussfläche des Kontaktpads mit der Anschlussfläche des Anschlussdrahts mittels der Nanodrähte in Kontakt gebracht wird.

With regard to the method, it is provided that the method is used to connect a connection wire, which has a connection surface, to a contacting element of a device, which has a connection surface, the The device has a substrate, a sensor element applied to a first partial area of the substrate, a contact pad applied to a second partial area of the substrate, and a contacting element applied to the contact pad, the contact pad being connected to the sensor element by means of at least one conductor track, comprising:

• Provision of a multiplicity of nanowires on the connection surface of the contact-making element and / or provision of a multiplicity of nanowires on the connection surface of the connection wire;
• Merging of the connection surfaces, so that the connection surface of the contact pad is brought into contact with the connection surface of the connection wire by means of the nanowires.

According to an advantageous embodiment of the method according to the invention, it is provided that the connection surface of the contacting element and / or the connection surface of the connection wire is heated to a temperature of at least 150.degree. The heat is supplied externally, for example, by placing the device in a suitable furnace. Alternatively, an electric current is passed through the connection by, for example, applying a positive pole to the connecting wire and applying a negative pole to the contact pad. The connection heats up due to the flow of current. The level of the electrical current is chosen so that the temperature of at least 150 ° C is reached.

In the event that only one of the two connection surfaces has nanowires, this process step is necessary in order to ensure sufficient strength of the connection.

In the event that both connection surfaces have nanowires, such a method step further increases the already sufficient strength of the connection.

• 1: ein erstes Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung; und
• 2: ein zweites Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung.

The invention is explained in more detail with reference to the following figures. Show it

• 1 : a first embodiment of a device according to the invention; and
• 2 : a second embodiment of a device according to the invention.

1 shows a first embodiment of a device according to the invention. The device 1 comprises a particularly planar substrate 100 , which is made of a metallic or ceramic material, or of a semiconductor material. On a surface of the substrate 100 is a sensor element 110 applied using common thick or thin layer techniques. This essentially consists of a sensitive or active layer, which in particular is structured. For example, it is a platinum layer which has a meandering structure and is designed to detect a temperature or to emit heat by applying an electrical power. To protect the sensor element 160 this is covered with one or more passivation layers made of glasses, glass ceramics and / or oxide layers.

The sensor element 110 is electrically connected to a contact pad via conductor tracks 120 connected. The contact pad 120 serves for connection to a system or a device of the customer, for example a control / evaluation unit by means of a connection wire 140 . With the connecting wire 140 it is in particular wire with a circular cross-section. Alternatively, it can also be a flat wire or leadframe. The connecting wire 140 can preferably consist of platinum, nickel, gold, silver, copper or alloys of these materials in coated or uncoated variants.

On the contact pad 120 a contacting element is applied, which is used for electrical and mechanical contacting of the connecting wire 140 with the contact pad 120 serves. In the present case, the contacting element comprises at least one on the contact pad 120 , or in the area of the contact pad 120 applied adhesive layer and a connection surface applied to the adhesive layer 130 . The connection surface 130 includes a variety of nanowires.

The connecting wire 140 also has a connection surface at one end region 130 ' on, which in turn has a large number of nanowires. To establish the electrical and mechanical connection, the two connection surfaces 130 , 130 ' pressed together. The nanowires of both connection surfaces are guided into one another and adhere to one another due to Van der Waals forces and mechanical anchoring. Since the nanowires are made of a metallic material, in particular copper, nickel, gold, platinum or silver, an electrical connection between the two connection surfaces is also established in this way.

The connection can then be heated to a temperature of at least 150 ° C. for a certain time in order to increase the mechanical stability. This can be done, for example, via a suitable furnace, or by passing an electrical current through the connection.

It can also be provided that not both connection surfaces 130 , 130 ' Have nanowires, but only one of the two connection surfaces 130 , 130 ' . In this case, the heat treatment is after the two connection surfaces have been brought together 130 , 130 ' necessary in order to be able to guarantee sufficient mechanical stability.

In order to provide additional mechanical stability, a cover layer 150 be provided, which is the end of the connecting wire 140 and the contacting element is essentially completely covered.

2 shows a second embodiment of the device according to the invention. This differs from the one in 1 The embodiment shown is that the contacting element also has a wire element 170 includes. This is on the contact pad 120 welded or soldered on. The wire element 170 advantageously corresponds to the connecting wire in terms of material and cross section 140 . Optionally, a cover layer can also be used 150 be provided, which is used to mechanically stabilize the soldered or welded connection.

The connection surface 130 is in this case at the end of the wire element 170 .

The placement of the nanowires and the mutual contacting can be configured analogously to the first exemplary embodiment.

List of reference symbols

1

contraption

100

Substrate

110

Sensor element

120

Contact pad

130, 130 '

Connection surfaces

140

Connecting wire

150

Cover layer

160

Passivation layer

170

Wire element

Claims (11)

Device (1) for acquiring a physical measured variable of a measuring medium, comprising: - a substrate (100); - A sensor element (110) applied to a first partial area of the substrate (100); - A contact pad (120) applied to a second partial area of the substrate (100), the contact pad (120) being connected to the sensor element (110) by means of at least one conductor track; - A contacting element which has a connection surface (130) and which is applied to the contact pad (120); and - A connection wire (140) which has a connection surface (130 ') on one end region, wherein the connection surface (130) of the contacting element has a plurality of nanowires and / or wherein the connection surface (130') of the connection wire (140) has a plurality of Has nanowires, the connection surface (130) of the contacting element and the connection surface (130 ') of the connection wire (140) being brought together in such a way that they contact one another by means of the nanowires. Device (1) according to Claim 1 wherein, in the event that the contacting element has nanowires, the contacting element has at least one adhesive layer, the adhesive layer being applied in the area of the contact pad (120) and the connection surface (130) being applied to the adhesive layer. Device (1) according to Claim 1 wherein, in the event that the contacting element is free of nanowires, the contacting element has a layer with a rough or porous surface applied to the contact pad (120). Device (1) according to Claim 2 or 3 wherein a cover layer (150) is provided which completely or partially covers the contacting element and the end region of the connecting wire (140). Device (1) according to Claim 1 wherein the contacting element comprises a wire element with a first and a second end region, wherein the first end region is connected to the contact pad (120) and wherein the connection surface (130) is arranged on the second end region. Device (1) according to at least one of the preceding claims, wherein the nanowires are attached to one side of the respective connection surface (130, 130 ') and essentially cover the respective connection surface (130, 130') over a large area. Device (1) according to at least one of the preceding claims, wherein the nanowires consist of a metal, in particular copper, silver, gold, nickel, platinum, or an alloy containing at least one of the aforementioned metals. Device (1) according to at least one of the preceding claims, wherein the nanowires are produced by means of an ion track etching process. Device (1) according to at least one of the preceding claims, wherein the sensor element (110) is a temperature sensor, a gas sensor, a flow sensor, a humidity sensor, a conductivity sensor, a pH sensor or a biosensor, or wherein the sensor element (110) is configured to do so is to emit heat when subjected to an electrical power. A method for connecting a connection wire (140), which has a connection surface (130 '), to a contacting element of a device (1), which has a connection surface (130), the device (1) having a substrate (100), one on a has a first partial area of the substrate (100) applied sensor element (110), a contact pad (120) applied to a second partial area of the substrate (100) and a contacting element applied to the contact pad (120), the contact pad (120) by means of at least one conductor track is connected to the sensor element (110), comprising: - Providing a plurality of nanowires on the connection surface (130) of the contacting element and / or providing a plurality of nanowires on the connection surface (130 ') of the connection wire (140); - Merging the connection surfaces (130, 130 '), so that the connection surface (130) of the contact pad (120) is brought into contact with the connection surface (130') of the connection wire (140) by means of the nanowires. Procedure according to Claim 10 wherein the connection surface (130) of the contacting element and / or the connection surface (130 ') of the connection wire (140) is heated to a temperature of at least 150 ° C.

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