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DE-102022209554-B4 - Connection of a sensor array to a measured object

DE102022209554B4DE 102022209554 B4DE102022209554 B4DE 102022209554B4DE-102022209554-B4

Abstract

Method for connecting a sensor arrangement (20) to a measurement object (2), the method comprising the steps (100) Provide - of a measured object (2), - a sensor arrangement (20) comprising a strain gauge (1) which is at least configured to detect tensile and compressive deformations of a measurement object (2), and an electronic module (19), - a first connecting foil (10a) and a second connecting foil (10b), each containing metallic materials (11, 12) which react exothermically when activated, (200) Placing the first connecting foil (10a) between the strain gauge (1) and the electronic module (19), (300) Activating the metallic materials (11, 12) of the first connecting foil (10a) such that the first connecting foil (10a) heats up in such a way that a metallurgical connection is created between the strain gauge (1) and the electronic module (19), wherein after activating the metallic materials (11, 12) of the first connecting foil (10a) an electronic connection exists between the strain gauge (1) and the electronic module (19), (400) Place the second connecting foil (10b) between the strain gauge (1) and the object being measured (2), and (500) Activating the metallic materials (11, 12) of the second connecting foil (10b) so that the second connecting foil (10b) heats up in such a way that a metallurgical bond is created between the strain gauge (1) and the object being measured (2).

Inventors

  • Philipp Lang
  • Erwin Biegger
  • Georg Tenckhoff

Assignees

  • ZF FRIEDRICHSHAFEN AG

Dates

Publication Date
20260513
Application Date
20220913

Claims (15)

  1. Method for connecting a sensor arrangement (20) to a measurement object (2), the method comprising the steps: (100) providing - a measurement object (2), - a sensor arrangement (20) comprising a strain gauge (1) configured at least to detect tensile and compressive deformations of a measurement object (2), and an electronic module (19), - a first connecting film (10a) and a second connecting film (10b), each containing metallic materials (11, 12) that react exothermically upon activation, (200) placing the first connecting film (10a) between the strain gauge (1) and the electronic module (19), (300) activating the metallic materials (11, 12) of the first connecting film (10a) such that the first connecting film (10a) heats up in such a way that a metallurgical bond is formed between the strain gauge (1) and the electronic module (19), wherein After activating the metallic materials (11, 12) of the first connecting foil (10a), an electronic connection is established between the strain gauge (1) and the electronic module (19), (400) placing the second connecting foil (10b) between the strain gauge (1) and the object being measured (2), and (500) activating the metallic materials (11, 12) of the second connecting foil (10b) so that the second connecting foil (10b) heats up in such a way that a metallurgical bond is created between the strain gauge (1) and the object being measured (2).
  2. Procedure according to Claim 1 , wherein the strain gauge (1) and the electronic module (19) are encapsulated in a common housing (18) in one step (600).
  3. Procedure according to one of the Claims 1 or 2 , where steps (400) and (500) follow step (300), which is followed by step (200).
  4. Procedure according to one of the Claims 1 or 2 , where steps (400) and (500) occur before step (200).
  5. Method according to one of the preceding claims, wherein the strain gauge (1) comprises a carrier layer (1a) facing the object being measured (2) and a measuring grid (1b).
  6. Method according to one of the preceding claims, wherein the strain gauge (1) and/or the first connecting foil (10a) has a metallized first solder layer (13) which is arranged in step (200) between the strain gauge (1) and the first connecting foil (10a).
  7. Method according to one of the preceding claims, wherein the first connecting film (10a) and/or the electronic module (19) has a metallized second solder layer (14) which is arranged in step (200) between the electronic module (19) and the first connecting film (10a).
  8. Procedure according to Claim 6 combined with Claim 7 , wherein - the first solder layer (13) is applied to the strain gauge (1) and/or the first interconnecting foil (10a), - the second solder layer (14) is applied to the electronic module (19) and/or the first interconnecting foil (10a), - the first interconnecting foil (10a) with the solder layers (13, 14) is placed between the strain gauge (1) and the electronic module (19) in step (200), and - the metallic materials (11, 12) of the first interconnecting foil (10a) are activated in step (300) such that the first interconnecting foil (10a) heats up to such an extent that the first solder layer (13) and the second solder layer (14) melt and the strain gauge (1) is connected by the melted first solder layer (13) and the melted The second solder layer (14) is soldered to the electronic module (19) to create the metallurgical connection.
  9. Method according to one of the preceding claims, wherein the object being measured (2) and/or the second connecting foil (10b) has a metallized third solder layer (21) which is arranged in step (400) between the object being measured (2) and the second connecting foil (10b).
  10. Method according to one of the preceding claims, wherein the second connecting foil (10b) and/or the strain gauge (1) has a metallized fourth solder layer (22) which is arranged in step (400) between the strain gauge (1) and the second connecting foil (10b).
  11. Procedure according to Claim 9 combined with Claim 10 , wherein - the third solder layer (21) is applied to the measuring object (2) and/or the second connecting foil (10b), - the fourth solder layer (22) is applied to the strain gauge (1) and/or the second connecting foil (10b), - the second connecting foil (10b) with the solder layers (21, 22) is placed between the measuring object (2) and the strain gauge (1) in step (400), and - the metallic materials (11, 12) of the second connecting foil (10b) are activated in step (500) so that the second connecting foil (10b) heats up in such a way that the third solder layer (21) and the fourth solder layer (22) melt and the measuring object (2) is soldered to the strain gauge (1) through the molten third solder layer (21) and the molten fourth solder layer (22) to create the metallurgical connection.
  12. Procedure according to Claim 8 or Claim 11 , wherein a fixing pad (9) which exerts a pressure (p) at least indirectly on the sensor arrangement (20) and/or on the object being measured (2) is used to counteract deformation of the solder layers (13, 14, 21, 22) and the respective connecting foil (10a, 10b) during activation and connection in step (300) and step (500), respectively.
  13. Procedure according to one of the Claims 6 until 12 , wherein the respective solder layer (13, 14, 21, 22) is formed from a nickel-containing material.
  14. Procedure according to one of the Claims 6 until 13 , wherein the respective solder layer (13, 14, 21, 22) comprises a nickel layer and a gold layer.
  15. Arrangement of a sensor arrangement (20) on a measuring object (2), wherein the sensor arrangement (20) has been connected to the measuring object (2) by a method according to one of the preceding claims.

Description

The invention relates to a connection between a strain gauge and a measuring object. In this context, a method for attaching the strain gauge to the measuring object and an arrangement of the strain gauge on the measuring object are particularly claimed. For various applications, it is necessary to attach a strain gauge to a larger mechanical component, the object being measured. This is important for the placement of the sensor system and for connecting the physical signals to be measured. Strain gauges are measuring devices for detecting tensile and compressive deformations. Even with slight deformations, their electrical resistance changes, and they are used as sensors for strain measurement. Sensors for force or deformation measurement are highly dependent on the bonding or adhesive layer between the strain gauge and the object being measured. The object can be made of various materials such as metal, silicon, or an organic material. The bonding layer must offer strong adhesion and be dimensionally stable to ensure good force and deformation transmission without (additional and unpredictable) damping or time delays. The sensor's performance over its lifetime depends on the long-term stability of the bonding layer, particularly its temperature, humidity, and chemical resistance, to prevent signal drift, signal amplitude shrinkage, and time delays. Adhesive bonding is a common method for attaching strain gauges to larger objects. The bonding layer is therefore an adhesive layer. While relatively easy to implement in industrial manufacturing, this usually requires a manual process that is time-consuming and cost-inefficient. Adhesive bonds are susceptible to varying temperature gradients, humidity/chemical exposure, and long-term aging. This can reduce signal quality or even destroy the sensor. Other bonding techniques are impractical due to process parameters involving high temperatures, mechanical pressures, or high vacuum or inert gas. Other methods require strong electromagnetic fields. In this context, "impractical" means that it could damage the strain gauge or the object being measured. From the DE 10 2013 002 144 A1 A joining method for thermally sensitive structures is described, in which two components are functionally joined using a joining aid designed as a reactive nanofoil. The nanofoil is first inserted between corresponding surface sections of the components to be joined, and subsequently causes at least partial formation of a connection structure. The method is characterized by the fact that activation of the nanofoil first melts a largely solid solder bonding layer on both corresponding surface sections of the components to be joined, and that the melt material, which is locally confined to one surface section, is then mixed with the melt material of the opposite surface section and the remaining reactants of the nanoreactive foil system in such a way that, after cooling and solidification of the entire melt material, a functional hard solder joint is formed. The thermal stress required for melting is applied only within the contour sections of the contacts to be joined, exclusively to solder bonding layers of the solder layer system. From the EP 3 839 460 A1 A sensor system is known that comprises a structural interconnect layer and a sensor. The structural interconnect layer is arranged on a structure and is a metallic alloy. The sensor comprises a non-metallic wafer and a sensor interconnect layer arranged on a surface of the non-metallic wafer. The sensor interconnect layer is a metallic alloy and is coupled to the structural interconnect layer via a metallic connection. The sensor is designed to acquire data from the structure through the metallic connection, the structural interconnect layer, and the sensor interconnect layer. From the EP 2 796 830 B1 A strain gauge is known. The strain gauge comprises a semiconductor chip with a plurality of piezoresistive elements formed on an end face of a semiconductor substrate, a connecting line unit electrically connected to a plurality of electrodes of the semiconductor chip, and a plate component connected to a back face of the semiconductor chip. From the WO 2016/199286 A1 A strain sensing system is known that comprises a semiconductor element for strain detection, a substrate for strain transfer to the semiconductor element, and a connecting material for connecting the semiconductor element to the substrate for strain transfer. Furthermore, the strain sensing system includes... The detection system comprises a strain gauge unit in which the semiconductor element, the interconnect material, and the substrate for strain transmission are sealed by means of a first sealing material. The strain gauge unit and a circuit substrate connected to the strain gauge unit are sealed by means of a second sealing material. The object of the present invention is to propose a novel connection between a strain gauge and a measuring object, which addresses t