RU2411473C1 - Method of making multilayer contact sensor in form of laminated film - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of making contact sensor in form of a laminated film involves making at least two layers, one from flexible dielectric material which is a thermoset polymer, laminated on two sides with a thermoplastic polymer on which a second layer is formed from current-conducting element. The method involves subsequent assembly of the element of the sensor to obtain a packet of alternating dielectric and current-conducting layers, connecting elements in the packet under thermocompression welding conditions with preliminary placement of the packet between two dielectric layers made from thermoset polymer, used as walls of the housing, laminated with the thermoplastic polymer only on the side adjacent to the packet. Two flexible members are used to squeeze the assembly and the outline of the sensor, which corresponds to the configuration of the measured object, is then formed. To make the element, a workpiece of the element of the sensor is made first via thermocompression welding with flexible dielectric material inserted in between. A drawing of the element of the sensor is then formed on the workpiece through double-side photochemical etching of metal sheets using a photomask set.

EFFECT: possibility of making film-type sensors with required characteristics, high reliability of the sensor and simple process of making said sensor.

6 cl, 2 dwg

Description

The invention relates to a technology for the manufacture of film threshold pressure sensors and is aimed at improving the reliability indicators of measuring and control equipment operating under conditions of high-speed mechanical loads, and can be used to manufacture contact thin-film sensors fixed directly to the surface of the measured objects.

A known method of manufacturing contact sensors in the form of a layered film (USSR AS No. 1605725, IPC G01L 7/08, publ. 01/15/94, bull. No. 1), including the formation on a flexible dielectric film, for example polyimide, thin-film conductive elements of a given circuit , heat treatment of the film, the assembly of the constituent elements of the sensor to obtain a packet of at least two films with conductive elements on them, which are subjected to compression under pressure. In this case, before assembling the package, a layer of adhesive - glue is applied to the surface of the conductive elements. In the case of objects of complex configuration, it is envisaged to manufacture elements of the sensor blank using a pattern that repeats the geometric features of the profile of the object.

The disadvantages of this method include the need to use adhesive for assembly of the sensor, which can lead to unauthorized separation of the thin-film layered sensor and, as a result, to a decrease in its reliability in determining the critical moment of destruction of the object wall or its significant deformation. In addition, the known method does not provide for the manufacture of sensor elements that allow the sensor to be installed along the entire surface of the measured object and in hard-to-reach areas that have severe restrictions on the geometric dimensions to determine the localization of failure at critical load.

Of the known manufacturing methods, the closest to the proposed technical essence is a method of manufacturing a thin-film sensor (Patent RU 2226677, IPC ⁷ G01L 1/00, G01L 7/00, G01L 7/08, 04/10/2004), including cutting blanks of conductive circuits an element of solid metal sheets, which are applied on both sides to a dielectric optically transparent two-sided laminated layer to obtain the components of the thin-film element so that these contours coincide, and heat treatment under pressure is carried out to connect all the layers of the package obtained at the same time, while one of the auxiliary elements is made of metal rubber, and the second is made of a plastic metal alloy.

The disadvantages of the prototype include the likelihood of punctures in the insulating layers of the sensor as a result of the presence of hard elements (metal braids) in the elastic element (metal braid), the inability to create sensors with small dimensions of the elements of the conductive topological pattern, the relatively high cost of the metal rubber used, the complexity of creating sensors with the required characteristics .

In contrast to the prototype, in which a layered film: metal-dielectric is created, the proposed method creates a layered film: metal-dielectric-metal due to the simultaneous thermocompression welding of a film of a thermosetting polymer (polyimide) 1, laminated on both sides with a layer of thermoplastic polymer (fluoroplastic) ) 2, with sheets of metal 3 (Fig. 1), which provides the same conditions for welding a flexible dielectric material with both sheets of metal, i.e. uniform melting of the thermoplastic polymer (fluoroplastic) layer 2 and the formation of a strong, evenly distributed bond between the mating layers of the sensor elements, while maintaining the connection between the base of the dielectric layer (thermosetting polymer - polyimide) 1 and the lamination layer (thermoplastic polymer - fluoroplastic) 2. As a result this increases the reliability of the connection layers. After welding, a photosensitive layer (photoresist) is applied to both sides of the obtained blank of the sensor element, the layer is exposed through photo masks, development and subsequent etching of the conductive layer with the formation of a topological pattern. As a result of using unified bases for obtaining the conductive topological pattern of the sensor contacts for combining photo masks for the exposure operation, high accuracy of combining various layers of the sensor is achieved. For uniform pressure and temperature distribution outside these bags during pressing, the following package of technological materials is used: polyimide film 1 - polyethylene film 4 - polyimide film 1.

Thermocompression welding of the billet of the sensor element, consisting of two metal sheets laid with a dielectric material, is carried out under a pressure of 1.8-2.0 MPa and at a temperature of 300-320 ° C for 5-6 minutes.

Obtained in a similar way, the sensor fragments 5, in accordance with the requirements of the sensor design, are collected in the required amount in bag 6 (Fig. 2), laying between them one or more layers of the above two-sided laminated dielectric material - polyimide 1, laminated with fluoroplastic 2. From the outside, the bag layers of a dielectric material (polyimide) 1, one-sidedly laminated on the side of the packet with a second dielectric material (fluoroplastic) 2, and then layers of a technological material for compression of the pressed assembly, consisting of the following films: fluoroplastic 2, polyethylene 4 and polyimide 1. In this case, the fluoroplastic film 2 is used instead of the polyimide to avoid the shift of the previously obtained topological patterns of the sensor contacts on the fluoroplastic coating due to the melting of the polyethylene film 4 under the above-mentioned high-temperature exposure . The thickness of the plastic film must be not less than the total thickness of the package of contacts of the sensor. If it is necessary to obtain a flat sensor surface from the installation side of the measurement object, a plastic film is not laid on this side. After removal of pressure and cooling of the assembly, the package of technological materials is freely removed.

The process of thermocompression welding of the package of sensor elements is carried out at a pressure of 1.8-2.0 MPa and at a temperature of 280-300 ° C for 5-6 minutes with preliminary heating of the press to 150 ° C.

The temperature range of the high-temperature pressing operation was selected on the basis of experimental work and meets the condition for the lamination layer (fluoroplastic) to exist in the molten state and the condition of maintaining its connection with the base of the dielectric layer (polyimide), which ensures the strength of the connection of the conductive element with the dielectric. These conditions correspond to the polymeric materials selected for high-temperature pressing and the temperature and pressure range. At temperatures below the claimed range, a complete and uniform melting of the lamination layer is not realized, which leads to a decrease in the reliability of the connection. At temperatures above the claimed range, the destruction of the thermosetting layer begins, which leads to a sharp deterioration in the electrical parameters of the sensor and the creation of harmful production conditions.

The pressure range for high-temperature pressing operations was selected based on experimental studies, taking into account comprehensive compression of the layers and obtaining reliable contact of the mating surfaces of the sensor elements.

Thus, the technical problem to which the invention is directed is to develop a method for manufacturing a disposable threshold pressure sensor with predetermined characteristics in the form of a laminated film fixed directly to the wall of the measured object.

A new technical result achieved using the proposed method is to provide the possibility of manufacturing film sensors with the required characteristics — the distance between the object’s body and the sensor’s contacts, the distances between the contacts, the number of contacts, various topological designs of the contacts, different capacities between the contacts themselves and between the contacts and the body of the object in order to reliably determine the moment of onset and localization of destruction in the body of the object, to increase the reliability awn manufactured sensor and to simplify the manufacturing process.

As experience in the practical implementation of the method showed, the use of thermocompression welding in the claimed ranges of parameter values, as well as the use of dielectric materials and conductive elements, does not require the creation of a specialized section, because there is no emission of toxic substances, and the set of layers of technological material proposed in the method of assembling the sensor elements for crimping the extruded assembly provides higher reliability in the finished sensor due to the high-quality crimping of the topology elements of sensors of any sizes without damaging them and without damaging the insulation layers while maintaining electrical parameters before the impact of critical loads on the measured object. In addition, it creates the possibility of obtaining a flat sensor surface from the installation side of the object.

In addition, the proposed method of performing the sensor in the form of a layered thin-film assembly allows the manufacture of sensors with the required parameters and install them in the bottlenecks of the object with strict restrictions on geometric dimensions; however, the Assembly of the sensor is carried out with less labor and using simpler and cheaper materials and, therefore, in a simpler way than in the prototype.

The proposed method of manufacturing a multilayer contact sensor in the form of a layered film is introduced into mass production.

Claims (6)

1. A method of manufacturing a contact sensor in the form of a layered film, comprising the implementation of at least two layers, one of which is made of a flexible dielectric material that is pressure sensitive and is a thermosetting polymer laminated on both sides with a thermoplastic polymer on which the second a layer of a conductive element, the subsequent assembly of the sensor element to obtain a package of alternating dielectric and conductive layers, the connection of the elements in a package under thermocouple conditions compression welding with preliminary placement of the bag between two thermosetting polymer dielectric layers used as body walls, laminated with thermoplastic polymer only from the side adjacent to the bag, in this case, two auxiliary elastic elements are used to compress the assembly, which are removed and finally formed after depressurization a sensor circuit corresponding to the configuration of the measured object, characterized in that the blank of the sensor element is first obtained using thermals mpressionnoy welding metal sheets with a flexible dielectric material, sandwiched between them, and then the workpiece is formed by the sensor element of Figure bilateral photochemical etching metal sheets using a set of photomasks. 2. The method according to claim 1, characterized in that the thermocompression welding of the billet of the sensor element, consisting of two metal sheets laid with flexible dielectric material, is carried out under a pressure of 1.8-2.0 MPa and at a temperature of 300-320 ° C for 5-6 minutes 3. The method according to claim 1, characterized in that as the outer packets of polymeric materials used in thermocompression welding of metal sheets with flexible dielectric material, a polyethylene film is used, laid on both sides with a polyimide film. 4. The method according to claim 1, characterized in that the combination of polyimide, fluoroplastic and polyethylene films is used as auxiliary elastic elements used to distribute the compression pressure of the packages of sensor elements. 5. The method according to claim 1, characterized in that the thermocompression welding of the package of sensor elements is carried out in the press, preheated to a temperature of 150 ° C, under a pressure of 1.8-2.0 MPa at a temperature of 280-300 ° C for 5- 6 minutes 6. The method according to claim 1, characterized in that the number of sensor elements and their conductive patterns are selected in such a way that, if necessary, when combining the patterns of the elements completely overlap the entire surface of the measurement object.

Images