A micro-nano film heat flow sensor based on a metal substrate and a manufacturing method thereof

Abstract

The application relates to a metal substrate-based micro-nano film thermal flow sensor and a manufacturing method thereof, and belongs to the technical field of sensors. The sensor mainly comprises a metal base, a metal transition layer I, a metal bonding layer I, an insulating layer I, photoresist, a metal sensing layer, a metal transition layer II, a metal bonding layer II, an insulating layer II, a metal protective sheet, a metal transition layer III, a metal bonding layer III and an epoxy resin; the manufacturing method is as follows: a metal base for sensor deposition is selected; transition layers, bonding layers, insulating layers, sensing layers and protective layers are deposited on the metal base layer by layer through process steps such as electroplating, spin coating, photolithography and magnetron sputtering, so as to form a typical sandwich layered structure. The application can effectively guarantee the use effect of the sensor in a harsh industrial environment, and help to greatly improve the service life of the sensor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sensors, and relates to a micro-nano film heat flow sensor based on a metal substrate and a manufacturing method thereof. BACKGROUND

[0002] Thermal field detection is a work often carried out in modern industrial production and scientific research, which mainly involves two physical quantities of temperature and heat flow. The full understanding of the dynamic change characteristics of the thermal field distribution and the heat transfer process and the correct analysis of the influencing factors of the related production process and product quality control are particularly important, and the latter often reflects the close relevance in the physical mechanism. For the detection of heat flow, the traditional thermocouple is difficult to apply in some scenes with strict installation space size limitation and dramatic instantaneous dynamic change due to its large size, slow response and other shortcomings. Even if it is used, the accuracy, reliability, timeliness and durability are greatly reduced. SUMMARY

[0003] Therefore, the present application aims to provide a micro-nano film heat flow sensor based on a metal substrate and a manufacturing method thereof.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] A micro-nano film heat flow sensor based on a metal substrate mainly comprises a metal substrate, a metal transition layer I, a metal bonding layer I, an insulating layer I, a metal sensing layer, a metal transition layer II, a metal bonding layer II, an insulating layer II, a metal protective sheet, a metal transition layer III, a metal bonding layer III and epoxy resin.

[0006] The metal substrate is a substrate, and the surface is electroplated with the metal transition layer I.

[0007] The thickness of the metal substrate ranges from 50μm to 800μm.

[0008] The metal transition layer I is sputtered with the metal bonding layer I on the surface.

[0009] The thickness of the metal bonding layer I and the metal bonding layer II ranges from 10nm to 100nm.

[0010] The thickness of the metal transition layer I and the metal transition layer II ranges from 5μm to 30μm.

[0011] The metal bonding layer I is coated with the insulating layer I on the surface.

[0012] The thickness of the insulating layer I and the insulating layer II ranges from 1μm to 5μm.

[0013] The surface of the metal sensing layer is electroplated with a metal transition layer II.

[0014] The metal sensing layer includes a first sensing circuit and a second sensing circuit.

[0015] The thickness of the metal sensing layer ranges from 300 nm to 900 nm.

[0016] The first electrode sensing circuit includes metal layer I, metal layer II and metal layer III deposited sequentially.

[0017] The second electrode sensing circuit is deposited on the surface of the first electrode sensing circuit, including metal layers IV, V and VI deposited sequentially.

[0018] The surface of the metal transition layer II is sputtered with a metal bonding layer II.

[0019] The surface of the metal bonding layer II is coated with an insulating layer II.

[0020] A metal protective sheet is bonded to the surface of the insulating layer II.

[0021] One surface of the metal protective sheet is electroplated with a metal transition layer III, and the other surface is coated with epoxy resin.

[0022] The insulating layer II and the metal bonding layer III are bonded together, thereby bonding the metal substrate and the metal protective sheet.

[0023] The metal transition layer III is sputtered with a metal bonding layer III.

[0024] Several thermopile circuits are deposited on a high-temperature micro / nano film heat flow sensor based on a metal substrate to achieve multi-point detection within a local area. One thermopile circuit includes a metal sensing layer, a metal transition layer II, a metal bonding layer II, an insulating layer II, and a metal protective sheet deposited sequentially.

[0025] Micro / nano film heat flow sensor based on metal substrate can withstand temperatures up to 400°C.

[0026] Micro / nano film heat flow sensors based on metal substrates detect heat flow by acquiring potential signals.

[0027] A method for fabricating a micro / nano-thin film heat flow sensor based on a metal substrate mainly includes the following steps:

[0028] Step 1: Select a metal substrate for sensor deposition.

[0029] The surface roughness of the metal substrate ranges from 100 nm to 400 nm.

[0030] Step 2, grinding and chemical mechanical polishing are performed on the metal substrate, and a metal transition layer I is deposited on the surface of the metal substrate by a magnetron sputtering process.

[0031] Step 3, a metal bonding layer I is deposited on the surface of the metal transition layer I by a magnetron sputtering process.

[0032] Step 4, an insulating layer I is coated on the surface of the metal bonding layer I by a spin coating process, and soft baking and curing are performed in a hot plate and an oven, respectively.

[0033] Step 5, a photoresist is coated on the surface of the insulating layer I by a spin coating process, and the metal substrate is pre-baked on a hot plate. Exposure is performed on a mask plate in a photoetching machine. After exposure, the metal substrate is post-baked on a hot plate. The metal substrate is developed in a developing solution, and a sensor stencil is obtained after drying.

[0034] Step 6, a metal sensing layer is deposited on the surface of the photoresist layer by a magnetron sputtering process, and the main steps are as follows:

[0035] Step 6.1, a metal layer I, a metal layer II and a metal layer III are sequentially deposited on the surface of the photoresist layer to form a first electrode sensing circuit.

[0036] Step 6.2, a metal layer IV, a metal layer V and a metal layer VI are sequentially deposited on the surface of the first electrode sensing circuit to form a second electrode sensing circuit, and then the photoresist is soaked and stripped in acetone and dried.

[0037] Step 7, based on the sensor stencil, a metal protective sheet is cut out.

[0038] The metal protective sheet is in the shape of a circular crown.

[0039] Step 8, a metal transition layer III is deposited on the surface of the metal protective sheet by an electroplating process, and a metal bonding layer III is deposited on the surface of the metal transition layer III by a magnetron sputtering process.

[0040] Step 9, an insulating layer II is coated on the surface of the metal sensing layer by a spin coating process.

[0041] Step 10, the metal protective sheet is attached to the metal substrate by the adhesion of the insulating layer II, and the solder pad is exposed.

[0042] Step 11, the metal substrate with the metal protective sheet is baked and cured, and then the insulating layer on the surface of the solder pad is removed by a plasma etching process.

[0043] Step 12, the solder pad is connected to the compensation wire by conductive silver glue, and then the surface is coated with epoxy resin after baking on a hot plate. The epoxy resin is cured.

[0044] The diameter of the compensation wire ranges from 0.2mm to 0.5mm.

[0045] It is worth mentioning that the micro-nano thin film heat flow sensor is made based on the ultra-clean room MEMS micro-electro-mechanical processing technology, wherein the main process links involve photoetching, magnetron sputtering, electron beam evaporation and atomic layer deposition processes, and it is a relatively more advanced and more advanced sensor technology, the working layer thickness is usually only hundreds of nanometers, and the protective layer is usually not more than 1mm, and the line width and node size of the working layer are in the micron level, the small size characteristics give it the technical characteristics of convenient and flexible installation, fast dynamic response, real and reliable detection, and multiple detection points can be reasonably arranged in a local small area through line optimization design, which can significantly improve the technical limitations of traditional detection components in these aspects, and the use of high hardness, high melting point and good thermal conductivity metal substrate as the protective layer can greatly improve the high temperature and high pressure resistance of the thin film sensor and the service life, providing an important hardware foundation for further optimization of heat flow detection scheme and further enrichment of detection means in various industrial scenes.

[0046] The application is based on the classic Seebeck effect and the thermoelectric pile principle of multiple K-type thermocouples in series, and a micro-nano thin film heat flow sensor capable of resisting 400 DEG C high temperature is made through the MEMS micro-electro-mechanical processing technology such as uniform glue spin coating, photoetching development and magnetron sputtering in an ultra-clean room, with a relatively high melting point and hardness, good thermal conductivity and electrical conductivity metal as a substrate sheet.

[0047] The technical effect of the application is self-evident, the micro-nano thin film sensor disclosed in the application has small size, fast response, small disturbance to the original thermal field, can timely and accurately capture the instantaneous dynamic change of the thermal field, obtain transient heat flow, can be flexibly and conveniently installed in a small space and closer to the detection point for detection, and multiple thermoelectric pile circuits can be arranged in a detection area at the same time to realize local multi-point detection according to requirements; the packaging mode based on the metal substrate with relatively high melting point and hardness and good thermal and electrical conductivity performance makes the sensor have good high temperature and high pressure resistance and anti-interference performance, can effectively guarantee the use effect of the sensor in harsh industrial environment, and helps to greatly improve the service life.

[0048] Other advantages, objects and features of the application will be set forth in part in the following specification, and in part will become apparent to those skilled in the art from the examination of the following specification, or can be learned from the practice of the application. The objects and other advantages of the application can be realized and obtained by the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to make the purpose, technical scheme and advantages of the present application more clear, the preferred detailed description of the present application will be given below in combination with the drawings, in which:

[0050] Figure 1 The schematic diagram for designing the micro-nano thin film heat flow sensor.

[0051] Figure 2 The schematic diagram for the structure after completing the electroplating of nickel on the substrate.

[0052] Figure 3 The schematic diagram for the structure after completing the sputtering of titanium on the substrate.

[0053] Figure 4 The schematic diagram for the structure after completing the spin coating of polyimide on the substrate.

[0054] Figure 5 The schematic diagram for the exposure & development process step.

[0055] Figure 6 The schematic diagram for the sputtering deposition of the metal sensing layer.

[0056] Figure 7 The schematic diagram for completing the deposition of the two-pole sensing loop.

[0057] Figure 8 The schematic diagram for the sandwich layer packaging structure after completing the RIE etching.

[0058] Figure 9 The schematic diagram for the core working layer of the micro-nano thin film heat flow sensor.

[0059] Figure 10 The schematic diagram for the structure of the metal sheet required for the sensor packaging.

[0060] The drawings show that: 1-metal substrate, 2-metal transition layer I, 3-metal bonding layer I, 4-insulating layer I, 5-photoresist, 6-metal sensing layer, 601-metal layer I, 602-metal layer II, 603-metal layer III, 604-metal layer IV, 605-metal layer V, 606-metal layer VI, 7-metal protection sheet, 8-compensation wire, 9-solder pad, 10-metal transition layer II, 11-metal bonding layer II, 12-insulating layer II, 13-metal transition layer III, 14-metal bonding layer III, 15-epoxy resin, A-cathode, B-anode, T0-lower end temperature sensing contact, T1-upper end temperature sensing contact. DETAILED DESCRIPTION

[0061] The present application is described and explained more fully by reference to the following detailed description. Other advantages of the present application will be realized and appreciated by those skilled in the art, and it will be understood to those skilled in the art that changes can be made to the description of the preferred embodiment of the present application without departing from the spirit and scope of the application. It is intended that each aspect of the present application included in this description be within the scope of the present application, with reference to the appended claims.

[0062] The drawings are only intended to schematically illustrate the basic concept of the present application, and cannot be understood as a limitation to the present application. Some components in the drawings are omitted, enlarged or reduced for better illustrating the embodiments of the present application, and do not represent the actual size of the product. It is understandable for those skilled in the art that some well-known structures and their descriptions in the drawings can be omitted.

[0063] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components. In the description of the present application, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "front", "back" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes, and cannot be understood as a limitation to the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0064] Embodiment 1:

[0065] Please refer to Figures 1 to 10 A metal substrate-based micro-nano thin film heat flow sensor mainly comprises a metal substrate (1), a metal transition layer I (2), a metal bonding layer I (3), an insulating layer I (4), a photoresist (5), a metal sensing layer (6), a metal transition layer II (10), a metal bonding layer II (11), an insulating layer II (12), a metal protective sheet (7), a metal transition layer III (13), a metal bonding layer III (14) and an epoxy resin (15).

[0066] The metal substrate (1) is a substrate, and the surface is electroplated with the metal transition layer I (2). The material of the metal substrate (1) is copper.

[0067] The metal transition layer I (2) is sputtered with the metal bonding layer I (3) on the surface. The material of the bonding layer is titanium.

[0068] The metal bonding layer I (3) is coated with the insulating layer I (4) on the surface.

[0069] During manufacturing, the surface of the insulating layer I (4) is coated with photoresist (5).

[0070] The surface of the photoresist (5) is deposited with a metal sensing layer (6).

[0071] The surface of the metal sensing layer (6) is electroplated with a metal transition layer II (10).

[0072] The metal sensing layer (6) comprises a first pole sensing circuit and a second pole sensing circuit.

[0073] The first pole sensing circuit comprises a metal layer I (601), a metal layer II (602) and a metal layer III (603) deposited in sequence.

[0074] The second pole sensing circuit is deposited on the surface of the first pole sensing circuit and comprises a metal layer IV (604), a metal layer V (605) and a metal layer VI (606) deposited in sequence. The metal layer I (601), the metal layer III (603), the metal layer IV (604) and the metal layer VI (606) are adhesive layers for improving the adhesion between the previous layer and the next layer.

[0075] The surface of the metal transition layer II (10) is sputtered with a metal adhesive layer II (11).

[0076] The surface of the metal adhesive layer II (11) is coated with an insulating layer II (12).

[0077] The surface of the insulating layer II (12) is bonded with a metal protective sheet (7).

[0078] One surface of the metal protective sheet (7) is electroplated with a metal transition layer III (13), and the other surface is coated with an epoxy resin (15).

[0079] The surfaces of the insulating layer II (12) and the metal adhesive layer III (14) are bonded, so that the metal substrate (1) and the metal protective sheet (7) are bonded.

[0080] The metal transition layer III (13) is sputtered with a metal adhesive layer III (14).

[0081] A plurality of groups of thermoelectric circuit are deposited on the high-temperature micro-nanometer thin film heat flow sensor based on a metal substrate to realize multi-point detection in a local area. One group of thermoelectric circuit comprises a metal sensing layer (6), a metal transition layer II, a metal adhesive layer II, an insulating layer II and a metal protective sheet (7) deposited in sequence.

[0082] The micro-nanometer thin film heat flow sensor based on a metal substrate can withstand a temperature of 400℃.

[0083] The metal substrate-based micro-nano thin film heat flow sensor detects heat flow by collecting electric potential signals.

[0084] Embodiment 2:

[0085] A metal substrate-based micro-nano thin film heat flow sensor, the main structure is shown in Embodiment 1, wherein,

[0086] The thickness of the metal base (1) is 50 μm;

[0087] The thickness of the metal transition layer I (2) and the metal transition layer II (10) is 5 μm;

[0088] The thickness of the metal bonding layer I (3) and the metal bonding layer II (11) is 10 nm;

[0089] The thickness of the insulating layer I (4) and the insulating layer II (12) is 1 μm;

[0090] The thickness of the metal sensing layer (6) is 300 nm.

[0091] Embodiment 3:

[0092] A metal substrate-based micro-nano thin film heat flow sensor, the main structure is shown in Embodiment 1, wherein,

[0093] The thickness of the metal base (1) is 800 μm;

[0094] The thickness of the metal transition layer I (2) and the metal transition layer II (10) is 30 μm;

[0095] The thickness of the metal bonding layer I (3) and the metal bonding layer II (11) is 100 nm;

[0096] The thickness of the insulating layer I (4) and the insulating layer II (12) is 5 μm;

[0097] The thickness of the metal sensing layer (6) is 900 nm.

[0098] Embodiment 4:

[0099] A metal substrate-based micro-nano thin film heat flow sensor, the main structure is shown in Embodiment 1, wherein,

[0100] The thickness of the metal base (1) is 425 μm;

[0101] The thickness of the metal transition layer I (2) and the metal transition layer II (10) is 17.5 μm;

[0102] The thickness of the metal bonding layer I (3) and the metal bonding layer II (11) is 55 nm;

[0103] The thickness of the insulation layer I (4) and the insulation layer II (12) is 3 μm.

[0104] The thickness of the metal sensing layer (6) is 600 nm.

[0105] Example 5:

[0106] A micro-nano film heat flow sensor based on a metal substrate is mainly as follows:

[0107] The metal is used as the substrate of the sensor. The transition layer, the adhesive layer, the insulation layer, the sensing layer and the protective layer are deposited layer by layer through the process steps of electroplating, spin coating, photolithography, and magnetron sputtering, forming a typical sandwich layered structure. The sensing layer is designed based on the thermocouple principle, that is, a plurality of K-type thermocouples are connected in series, and two different nickel-based alloys are used as the two electrode materials of the thermocouple loop. The heat flow value of the detection point is obtained by reading the amplified thermoelectric power signal. A plurality of thermocouple loops can be deposited on the sensing layer of the same substrate to realize multi-point detection in a narrow local area, with high spatial resolution. Even if one detection point is damaged, the remaining detection points can still work normally, and the detection redundancy is good. The sensor film thickness is only a few hundred nanometers, the line width and the size of the hot junction are small, the mass and the heat capacity are small, the response to the rapid change of the thermal field is fast, the response time can reach the microsecond level, and the real thermal field of the detection point has less destructive interference. The sensor uses metal with good electrical conductivity and thermal conductivity as the protective layer, and uses high-molecular-weight insulating material with good thermal stability and mechanical properties as the insulation layer, which can reliably realize heat flow detection in a 400℃ environment. A layer of metal similar to the substrate and with good thermal and electrical conductivity and strength is electroplated on the substrate as a transition layer. A layer of metal is sputtered on the upper and lower sensing layer alloy materials as an adhesive layer to effectively enhance the bonding between the sensing layer and the insulation layer and prevent delamination. The sensor pad uses a conductive adhesive material that can withstand high temperatures as the wire connection material, which can ensure the reliability and stability of the sensor in long-term high-temperature environments.

[0108] The metal with good electrical conductivity and thermal conductivity, relatively high melting point and hardness is used as the substrate of the sensor.

[0109] The sensor is a typical sandwich layered structure, including a transition layer, an adhesive layer, an insulation layer, a sensor, and a protective layer, which are deposited layer by layer through processes such as electroplating, spin coating, photolithography, and magnetron sputtering. The thickness of the transition layer is 5 μm to 30 μm, the thickness of the adhesive layer is 10 nm to 100 nm, the thickness of the insulation layer is 1 μm to 5 μm, and the thickness of the sensing layer is 300 nm to 900 nm.

[0110] The sensor is designed based on the thermoelectric principle of series multi-group K-type thermocouples, and uses NiCr-NiAlMnSi, NiCr-NiAl, and NiCr-NiSi alloys as the two-pole materials of the thermocouple loop.

[0111] The multiple thermocouple loops are simultaneously deposited on the sensing layer of the same substrate, so as to realize multi-point detection in a narrow local area.

[0112] The sensor film is as thin as several hundred nanometers, and has small line width and thermal junction size, small mass and heat capacity, and can quickly reflect the transient change of the thermal field, with response time reaching the microsecond level and less destructive interference to the real thermal field of the detection point.

[0113] The sensor uses polyimide with good thermal stability and mechanical properties as the insulating layer, and can reliably realize heat flow detection in a 400℃ environment.

[0114] A layer of metal titanium is sputtered on the surface of the transition layer as a bonding layer to effectively enhance the bonding property of the metal substrate and the insulating layer.

[0115] A layer of metal titanium is sputtered on the upper and lower surfaces of the sensing layer as a bonding layer to effectively enhance the bonding property between the sensing layer and the insulating layer.

[0116] The sensor pad uses a two-component conductive silver adhesive as the wire connection material, which can ensure the reliability and stability of the sensor in long-term high-temperature environment.

[0117] The cathode of the micro-nano thin film heat flow sensor on the metal substrate is marked as A, the anode is marked as B, the upper temperature sensing point is marked as T1, and the lower temperature sensing point is marked as T0.

[0118] Example 6:

[0119] A manufacturing method of a micro-nano thin film heat flow sensor based on a metal substrate mainly includes the following steps:

[0120] 1) Select a metal substrate (1) for sensor deposition.

[0121] The surface roughness of the metal substrate (1) is in the range of 100nm-400nm.

[0122] 2) Grind and chemically mechanically polish the metal substrate (1), and deposit a metal transition layer I (2) on the surface of the metal substrate (1) by a magnetron sputtering process.

[0123] 3) Deposit a metal bonding layer I (3) on the surface of the metal transition layer I (2) by a magnetron sputtering process.

[0124] 4) Insulating layer I (4) is coated on the surface of metal adhesive layer I (3) by spin coating process, and soft baking and curing are carried out in a hot plate and an oven respectively.

[0125] 5) Photoresist (5) is coated on the surface of insulating layer I (4) by spin coating process, and the metal substrate (1) is pre-baked on a hot plate. Exposure is carried out on a photoetching machine using a mask plate. After exposure, the metal substrate 1 is post-baked on a hot plate. The metal substrate (1) is placed in a developing solution for development, and a sensor pattern is obtained after drying.

[0126] 6) Metal sensing layer (6) is deposited on the surface of the photoresist layer by magnetron sputtering process, and the main steps are as follows:

[0127] 6.1) Metal layer I (601), metal layer II (602) and metal layer III (603) are sequentially deposited on the surface of the photoresist layer to form a first electrode sensing circuit.

[0128] 6.2) Metal layer IV (604), metal layer V (605) and metal layer VI (606) are sequentially deposited on the surface of the first electrode sensing circuit to form a second electrode sensing circuit, and then the photoresist (5) is soaked in acetone for stripping and dried after post-baking.

[0129] 7) Based on the sensor pattern, a metal protective sheet (7) is cut out.

[0130] The metal protective sheet (7) is in the shape of a circular crown.

[0131] 8) Metal transition layer III (13) is deposited on the surface of the metal protective sheet (7) by electroplating process, and metal adhesive layer III (14) is deposited on the surface of the metal transition layer III (13) by magnetron sputtering process.

[0132] 9) Insulating layer II (12) is coated on the surface of the metal sensing layer (6) by spin coating process.

[0133] 10) The metal protective sheet (7) is attached to the metal substrate (1) by the adhesion of the insulating layer II, and the solder pad (9) is exposed.

[0134] 11) The metal substrate (1) with the metal protective sheet (7) attached is baked and cured, and then the insulating layer on the surface of the solder pad (9) is removed by plasma etching process.

[0135] 12) The solder pad (9) is connected to the compensation wire (8) by conductive silver paste, and then the surface is coated with epoxy resin after baking on a hot plate. The epoxy resin (15) is cured.

[0136] The diameter of the compensation wire (8) ranges from 0.2 mm to 0.5 mm.

[0137] Example 7:

[0138] A method for manufacturing a micro-nano thin film heat flow sensor based on a metal substrate, mainly as follows:

[0139] 1) According to the requirements of heat flow detection, a micro-nano thin film heat flow sensor is designed and manufactured, including the shape, size and number of the sensor, as shown in Figure 1 .

[0140] 2) A 4" diameter, 800 μm thick metal is used as the substrate for sensor deposition. After polishing and grinding, a 5 μm to 30 μm thick metal transition layer is deposited on the surface, as shown in Figure 2 .

[0141] 3) A 10 nm to 100 nm thick titanium metal layer is deposited on the surface of the transition layer by magnetron sputtering process, as shown in Figure 3 .

[0142] 4) A 1 μm to 5 μm thick organic polymer material polyimide is coated on the surface of the titanium layer by spin coating process, and soft baking and curing are performed in a hot plate and an oven, respectively, as shown in Figure 4 .

[0143] 5) A 1 μm to 5 μm thick photoresist is coated on the surface of the insulating layer by spin coating process, and pre-baking is performed on a hot plate, then exposure is performed on a photoetching machine using a mask plate, after which post-baking is performed on a hot plate, followed by development in a developing solution, and after washing and drying, a mask plate with the shape and size of the sensor is formed, as shown in Figure 5 .

[0144] 6) Three metal layers are sequentially deposited on the surface of the photoresist layer by magnetron sputtering process, namely a 10 nm to 100 nm thick titanium metal layer, a 300 nm to 900 nm thick nickel-based alloy layer, and a 10 nm to 100 nm thick titanium metal layer, forming a first electrode sensing circuit.

[0145] 7) Repeat the above process steps to sequentially deposit titanium metal, another electrode nickel-based alloy, and titanium metal, forming a second electrode sensing circuit, then immerse in acetone to strip the photoresist and dry, as shown in Figure 6 and Figure 7 .

[0146] 8) The protective layer metal sheet in the shape of a circular crown is cut according to the size characteristics of the sensor, and a transition layer and an adhesive layer are sequentially deposited by electroplating process and magnetron sputtering process, respectively.

[0147] 9) Through the uniform glue spin coating process on the finished sensor layer again coated a thickness of 1 μm ~ 5 μm polyimide, using its adhesive will be the copper sheet in the last step of the processing good paste to the substrate, just bare exposed pad site, then baked to form a sandwich layer structure, and finally through the plasma etching process to remove the insulating layer on the surface of the pad, exposed lead pads, see Figure 8 .

[0148] 10) using conductive silver paste on the sensor layer all pad connection compensation wire, after hot plate baking and curing again coated a layer of epoxy, after 10 hours ~ 36 hours of aging curing after the completion of the entire sensor production, through the acquisition of potential signal to detect heat flow, the sensor layer is its core working layer, see Figure 9 .

[0149] Example 8:

[0150] A kind of metal substrate based micro-nano film heat flow sensor manufacturing method, mainly as follows:

[0151] 1) first according to the requirement of heat flow detection, design of micro-nano film heat flow sensor, such as Figure 1 , which includes the shape, size and number of sensor. The design of the sensor is based on the thermoelectric principle of Seebeck effect and the thermoelectric pile principle of series K type thermocouple, that is: two different conductors are used as anode and cathode, and are connected closely at both ends to form a closed loop, when the two junction temperature is not equal, T1 > T0, the loop will generate electromotive force, thus forming a thermoelectric current; a plurality of thermocouples with the same physical properties are connected in series to form a thermoelectric pile, the temperature difference potential between the two points in the heat transfer direction will be amplified, and the amplification factor depends on the number of series. A key indicator of thermoelectric pile is sensitivity, that is, the thermoelectric potential output under unit heat flow, which depends on the thermal conductivity of the substrate material, the number of series of thermocouples and the distance between the upper and lower temperature sensing joints, and satisfies, good design must ensure that it has enough sensitivity. The sensor uses a thermoelectric pile composed of multiple K type thermocouples in series, and selects K type thermocouple alloy as the sensor layer. According to the demand, a plurality of sensors are arranged on the substrate, and each sensor can be arranged with a plurality of thermoelectric pile loops. The loop wiring design should be symmetrical and beautiful as far as possible and convenient for cutting and processing. At the same time, when considering the plane size of the sensor, the success rate of sensor production should also be considered, that is, the line width size of a single electrode and the distance between each pair of electrodes should not be too small. In addition, in order to reduce the difficulty of lead connection and ensure the insulation between each pair of pads, the side length of a single square pad and the distance between each pair of pads should not be too small.

[0152] 2) A 4” diameter, 800μm thick copper sheet is used as the substrate for sensor deposition. Copper has a melting point of approximately 1083℃, a boiling point of approximately 2567℃, and a Vickers hardness of approximately 350MPa. It has good ductility and thermal and electrical conductivity, and is a relatively inert heavy metal. Considering both thermal conductivity and material strength, it is a suitable choice as the protective layer. After polishing, the copper sheet should be ensured to have low surface roughness, a smooth surface, and no obvious scratches or pits. Pretreatment such as substrate cleaning and deposition of the transition layer is then performed.

[0153] To enhance the adhesion between the metal substrate and the subsequent insulating layer, a 10nm–100nm thick titanium layer needs to be deposited on the transition layer surface using magnetron sputtering as a bonding layer, such as… Figure 3 As shown, if the substrate surface is relatively rough, the deposition thickness can be appropriately increased. Sputtering involves bombarding the surface of a solid target with plasma carrying kinetic energy of tens of electron volts or more. Atoms near the surface gain some of the energy carried by the incident particles. When this energy is sufficient to overcome the binding energy, these atoms detach from the solid and enter the vacuum chamber, subsequently depositing onto the substrate. Specific sputtering process parameters are: sputtering power 200W–600W, sputtering rate 10nm / min–20nm / min, and sputtering time 2min–6min. Of course, these parameters may be adjusted for different equipment platforms.

[0154] 3) Next, an insulating layer needs to be fabricated. This involves applying a layer of polyimide to the titanium surface using a spin coating process. Polyimide exhibits excellent thermal and mechanical properties, with a thermal decomposition temperature as high as 500℃~600℃ and a long-term service temperature range of -200℃~300℃. It has no obvious melting point, making it one of the most thermally stable polymers. It also possesses excellent mechanical properties and heat aging resistance, with a tensile strength of approximately 170MPa~400MPa and an elastic modulus of approximately 3GPa~4GPa. Even after aging at 200℃ for 1500 hours, the tensile strength shows minimal decrease. It exhibits high insulation properties, with a dielectric constant typically around 3.4 and a dielectric loss of only 0.004~0.007, classifying it as an F to H grade insulating material. First, spin coating is performed on the substrate using a spin coater. Then, soft baking is performed on a hot plate. Finally, it is baked and cured in an oven. Considering both good thermal conductivity and insulation protection, a thickness of 0.5μm~5μm after baking and curing is deemed appropriate for this insulating layer.

[0155] 4) To fabricate the designed sensor pattern for the next step of sputtering and depositing the metal sensing layer, a 1μm–5μm thick layer of photoresist needs to be coated onto the insulating layer surface using a spin coating process. Then, pre-baking is performed on a hot plate to remove solvents from the photoresist and enhance adhesion. Next, the pre-baked substrate is placed on a lithography machine for exposure. After exposure, the substrate is placed on a hot plate for post-baking to stimulate the acid generated by the PAG photosensitive acid generator in the chemically enhanced photoresist to react with the protecting groups on the photoresist and remove these groups, allowing it to dissolve in the developer while reducing standing wave effects. Subsequently, the post-baked substrate is placed in the developer for development. After development, it is rinsed with deionized water and dried with nitrogen gas, ultimately forming the pattern of the sensor shape and size, as shown below. Figure 5 As shown.

[0156] 5) Next, we begin fabricating the core metal sensing layer. First, a 10nm–100nm thick layer of titanium is sputtered using the process described in step 3. Then, a 300–900nm thick layer of nickel-based alloy is deposited using magnetron sputtering. The specific sputtering parameters are: sputtering power 200W–600W, sputtering rate 10nm / min–20nm / min, and sputtering time 30min–80min. These parameters may be adjusted for different equipment platforms. Then, another 10–100nm thick layer of titanium is sputtered using the process described in step 3. After deposition, the deposition of the first-stage sensing circuit is completed, as follows: Figure 6 As shown.

[0157] 6) Repeat the above process steps to sputter and deposit a 10nm–100nm thick layer of metallic titanium. Next, sputter and deposit a 300nm–900nm thick layer of nickel-based alloy for the other electrode. Specific sputtering parameters are: sputtering power 200W–600W, sputtering rate 10nm / min–20nm / min, and sputtering time 30min–80min. These parameters may be adjusted for different equipment platforms. Then, sputter and deposit another 10nm–100nm thick layer of metallic titanium. After deposition, the second electrode sensing circuit is complete. After immersion in the photoresist stripping solution, clean and dry. Figure 7 As shown. This completes the fabrication of the core sensing layer.

[0158] 7) To enhance the durability of thin-film sensors by preventing wear and corrosion in harsh environments, encapsulation protection is necessary. First, a crown-shaped copper sheet is cut according to the sensor's dimensions. Then, using electroplating and magnetron sputtering processes, a transition metal layer with a thickness of 5μm–30μm and a binder layer of titanium with a thickness of 10nm–100nm are sequentially deposited on the copper sheet surface to prepare for the next encapsulation step. Figure 10 As shown.

[0159] 8) Next, first, a polyimide layer with a thickness of 1-5 microns is coated on the prepared sensor layer by a spin coating process, and the copper sheet prepared in the previous step is attached to the substrate by using the adhesion of the polyimide, so as to expose the pad part, and then baking and curing in an oven to form a sandwich layer packaging structure, and finally the insulating layer on the surface of the pad is removed by a plasma etching process to expose the pad for the lead wire.

[0160] 9) Next, the final wiring step is performed. First, conductive silver paste is used to connect a compensation lead wire with a diameter of 0.2-0.5 mm to all the pads on the sensor layer, and then after hot plate baking, a layer of epoxy resin is applied for coverage to reduce the influence of external force on the bonding part of the lead wire and the pad, prevent the lead wire from being disconnected, and after 10-36 hours of aging and curing, the entire sensor is completed, which detects heat flow by collecting potential signals, and the sensor layer is the core working layer, as shown in Figure 9 .

[0161] The micro-nano thin film sensor based on the metal substrate has small size, fast response, and small interference to the original thermal field, can timely and accurately capture the instantaneous dynamic change of the thermal field, obtain transient heat flow, can be flexibly and conveniently installed in a small space and closer to the detection point for detection, and multiple thermocouple loops can be arranged in a detection area according to the needs to realize local multi-point detection; the sandwich layer packaging structure based on the metal copper substrate with relatively high melting point hardness and good thermal and electrical conductivity makes the sensor have good high temperature and high pressure resistance and anti-interference performance, can effectively avoid wear and corrosion, and can effectively guarantee the use effect of the thin film sensor in harsh industrial environments, and help to greatly improve the durability and service life. The present application can significantly improve the technical limitations and disadvantages of the conventional heat flow detection assembly in terms of space size, dynamic response and packaging protection, and provides an important hardware foundation and technical means for the optimization and innovation of the conventional heat flow detection method, and is worth popularizing and applying in various heat flow detection fields.

[0162] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A micro / nano-thin film heat flow sensor based on a metal substrate, characterized in that: It includes a metal substrate (1), a metal transition layer I (2), a metal adhesive layer I (3), an insulating layer I (4), a metal sensing layer (6), a metal transition layer II (10), a metal adhesive layer II (11), an insulating layer II (12), a metal protective sheet (7), a metal transition layer III (13), and an epoxy resin (15). The metal substrate (1) is a substrate, and a metal transition layer I (2) is electroplated on its surface. The surface of the metal transition layer I (2) is sputtered with a metal bonding layer I (3); The surface of the metal bonding layer I (3) is coated with an insulating layer I (4); A metal sensing layer (6) is deposited on the surface of the insulating layer I (4); The surface of the metal sensing layer (6) is electroplated with a metal transition layer II (10). The metal sensing layer (6) includes a first-pole sensing circuit and a second-pole sensing circuit; The first electrode sensing circuit includes metal layer I (601), metal layer II (602) and metal layer III (603) deposited sequentially. The second electrode sensing circuit is deposited on the surface of the first electrode sensing circuit, including metal layer IV (604), metal layer V (605) and metal layer VI (606) deposited sequentially. The surface of the metal transition layer II (10) is sputtered with a metal bonding layer II (11). The surface of the metal bonding layer II (11) is coated with an insulating layer II (12); A metal protective sheet (7) is bonded to the surface of the insulating layer II (12). The metal protective sheet (7) is electroplated with a metal transition layer III (13) on its lower surface opposite to the insulating layer II (12), and the other surface is coated with epoxy resin (15).

2. The micro / nano-thin film heat flow sensor based on a metal substrate according to claim 1, characterized in that, The surface of the metal transition layer III (13) is sputtered with a metal bonding layer III (14), and the surfaces of the insulating layer II (12) and the metal bonding layer III (14) are bonded together, thereby bonding the metal substrate (1) and the metal protective sheet (7).

3. The micro / nano film heat flow sensor based on a metal substrate according to claim 1, characterized in that: The thickness of the metal substrate (1) ranges from 50 μm to 800 μm; The thickness range of the metal transition layer I (2) and the metal transition layer II (10) is 5μm~30μm; The thickness range of the metal bonding layer I (3) and the metal bonding layer II (11) is 10nm~100nm; The thickness range of the insulating layer I (4) and the insulating layer II (12) is 1μm~5μm; The thickness of the metal sensing layer (6) ranges from 300 nm to 900 nm.

4. A method for fabricating a micro / nano-thin film heat flux sensor based on a metal substrate, characterized in that, Includes the following steps: Step 1: Select a metal substrate (1) for sensor deposition as the substrate; Step 2: Grind and chemically mechanically polish the metal substrate (1), and deposit a metal transition layer I (2) on the surface of the metal substrate (1) by magnetron sputtering. Step 3: Deposit a metal bonding layer I (3) on the surface of the metal transition layer I (2) by magnetron sputtering. Step 4: Apply insulating layer I (4) to the surface of metal bonding layer I (3) by spin coating process, and perform soft baking and curing in hot plate and oven respectively; Step 5: Apply photoresist (5) to the surface of insulating layer I (4) by spin coating process, and pre-bake the metal substrate (1) on a hot plate; expose the substrate using a photomask on a photolithography machine; After exposure, the metal substrate (1) is post-baked on a hot plate; The metal substrate (1) was placed in the developing solution for development and dried to obtain the sensor plate; Step 6: Deposit a metal sensing layer on the surface of the photoresist layer using a magnetron sputtering process (6). Step 7: Cut out the metal protective sheet (7) based on the sensor pattern. Step 8: Deposit a metal transition layer III (13) on one surface of the metal protective sheet (7) using an electroplating process, and then deposit a metal bonding layer III (14) on the surface of the metal transition layer III (13) using a magnetron sputtering process. Step 9: Apply insulating layer II (12) to the surface of the metal sensing layer (6) by spin coating process. Step 10: Using the adhesive properties of insulating layer II (12), the surface of the metal protective sheet (7) deposited with metal transition layer III (13) and metal bonding layer III (14) is attached to the metal substrate (1), and the pads (9) are exposed. Step 11: Bake and cure the metal substrate (1) with the metal protective sheet (7) attached, and then remove the insulating layer on the surface of the pad (9) by plasma etching process; Step 12: Connect the pad (9) to the compensating wire (8) using conductive silver paste, and then coat the surface with epoxy resin (15) after baking with a hot plate; cure the epoxy resin (15).

5. The method according to claim 4, characterized in that, The magnetron sputtering process deposits a metal sensing layer (6) on the surface of the photoresist layer, and the steps are as follows: Step 6.1: Sequentially deposit metal layer I (601), metal layer II (602) and metal layer III (603) on the surface of the photoresist layer to form the first electrode sensing circuit; Step 6.2: After depositing metal layer IV (604), metal layer V (605) and metal layer VI (606) sequentially on the surface of the first electrode sensing circuit to form the second electrode sensing circuit, place it in acetone for immersion to remove photoresist (5) and then dry it.

6. The method according to claim 4, characterized in that, The surface roughness of the metal substrate (1) ranges from 100 nm to 400 nm.

7. The method according to claim 4, characterized in that, The metal protective plate (7) is crown-shaped.

8. The method according to claim 4, characterized in that, The diameter of the compensating conductor (8) ranges from 0.2 mm to 0.5 mm.

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