Humidity sensing device and method of manufacturing the same

Abstract

A humidity sensing device and a method of manufacturing the same are provided. The humidity sensing device includes a flexible absorbent baseboard, a wiring layer, a humidity sensing module, and a conductive adhesive structure. The flexible absorbent baseboard has a first surface and a second surface that face each other. The wiring layer is disposed on the first surface and has a ground portion. The humidity sensing module is disposed on the first surface and electrically connected to the wiring layer. The conductive adhesive structure is disposed on the flexible absorbent baseboard and electrically connected to the ground portion.

Description

Technical Field

[0001] This application relates to a humidity sensing device and a method for manufacturing the same. Prior Technology

[0002] Artificial intelligence (AI) servers are computing systems designed for processing AI training and inference. Because AI servers generate significant heat when processing large amounts of complex data, they require robust cooling mechanisms to extend their lifespan. Currently, liquid cooling, such as water cooling, is used in AI servers. For example, in a liquid-cooled AI server, liquid cooling pipes are distributed near the most heat-prone electronic components. The generated heat is conducted to the liquid cooling pipes, where the circulating liquid carries it away, achieving effective heat dissipation.

[0003] A drawback of using liquid cooling is that leaks in the liquid cooling pipes can damage electronic components. Therefore, liquid-cooled AI servers need to use humidity sensors to detect leaks. Furthermore, the humidity of the environment in which the AI ​​server operates also affects its performance. For example, low humidity increases the risk of electrostatic discharge, making electronic components more susceptible to damage. High humidity increases the difficulty of cooling. However, commercially available humidity sensors can only detect leaks or ambient humidity from one side only. Summary of the Invention

[0004] At least one embodiment of this application provides a humidity sensing device and a method for manufacturing the same, which utilizes its structure to simultaneously sense humidity on both sides.

[0005] At least one embodiment of this application provides a humidity sensing device comprising a flexible moisture-absorbing substrate, a circuit layer, a humidity sensing module, and a conductive adhesive structure. The flexible moisture-absorbing substrate has a first surface and a second surface opposite to each other. The circuit layer is disposed on the first surface and has a grounding portion. The humidity sensing module is disposed on the first surface and electrically connected to the circuit layer. The conductive adhesive structure is disposed on the flexible moisture-absorbing substrate and electrically connected to the grounding portion.

[0006] The method for manufacturing a humidity sensing device provided in at least one embodiment of this application includes: providing a flexible substrate, wherein the flexible substrate includes a flexible moisture-absorbing substrate and a metal layer, and the flexible moisture-absorbing substrate and the metal layer are stacked; patterning the metal layer to form a circuit layer and a humidity sensing module, wherein the circuit layer is electrically connected to the humidity sensing module; and providing a conductive adhesive structure on the ground portion of the circuit layer.

[0007] The method for manufacturing a humidity sensing device provided in at least one embodiment of this application includes: providing a flexible substrate, wherein the flexible substrate includes a flexible moisture-absorbing substrate, a first metal layer and a second metal layer, the flexible moisture-absorbing substrate, the first metal layer and the second metal layer are stacked, and the flexible moisture-absorbing substrate is located between the first metal layer and the second metal layer; forming a conductive structure, wherein the conductive structure extends from the first metal layer to the second metal layer and is electrically connected to the first metal layer and the second metal layer; patterning the first metal layer to form a first circuit layer and a first humidity sensing module, wherein the first circuit layer is electrically connected to the first humidity sensing module; patterning the second metal layer to form a second circuit layer and a second humidity sensing module, wherein the second circuit layer is electrically connected to the second humidity sensing module, and the conductive structure is electrically connected to the first circuit layer and the second circuit layer; and after forming the second circuit layer, providing a conductive adhesive structure at a ground portion of the second circuit layer.

[0008] Based on the above, in the humidity sensing device disclosed in the above embodiments, the flexible moisture-absorbing substrate can absorb humidity in two opposite directions, so that the humidity sensing device can sense the humidity on both sides at the same time. Simple Explanation of the Diagram

[0009] To gain a more complete understanding of the embodiments and their advantages, the following description, taken in conjunction with the accompanying drawings, is provided, wherein: [Figure 1] is a cross-sectional schematic diagram of a humidity sensing device disposed in an electronic device according to at least one embodiment of this application; [Figure 2] is a surface schematic diagram of the electronic device in Figure 1; [Figure 3A] and [Figure 3B] are schematic diagrams of the bent electrode structure and the interdigitated electrode structure of the humidity sensing module in Figure 1, respectively; [Figure 4] is a cross-sectional view of a humidity sensing device disposed in an electronic device according to another embodiment of this application; Figures 5, 6, 7, and 8 are cross-sectional schematic diagrams of the steps in the manufacturing method of the humidity sensing device in Figure 1, namely, providing a flexible substrate, forming a circuit layer and a humidity sensing module, setting a cover layer and forming a plating layer, and setting a conductive adhesive structure, an insulating moisture-absorbing adhesive layer, a temperature sensing module, and a resistive element; and [Figure 9], [Figure 10], [Figure 11] and [Figure 12] are cross-sectional schematic diagrams of the steps in the manufacturing method of the humidity sensing device in Figure 4, namely, providing a flexible substrate, forming a conductive structure, forming a circuit layer and a humidity sensing module, and setting a cover layer and forming a plating layer. Implementation

[0010] In the following text, to clearly present the technical features of this application, the dimensions (e.g., length, width, thickness, and depth) of elements (e.g., layers, films, substrates, and regions) in the drawings will be enlarged proportionally, and the number of some elements may be reduced. Therefore, the description and explanation of the embodiments below are not limited to the number of elements in the drawings and the size and shape of the elements, but should cover the dimensions, shapes, and deviations from both caused by actual manufacturing processes and / or tolerances. Furthermore, for the clarity of the following embodiments, elements with the same or similar functions are represented by the same designation.

[0011] Figure 1 is a cross-sectional view of a humidity sensing device 100A disposed on an electronic device 200 according to at least one embodiment of this application, and Figure 2 is a schematic diagram of the surface 201 of the electronic device 200 of Figure 1. Referring to Figures 1 and 2, the humidity sensing device 100A can be disposed on the surface 201 of the electronic device 200. The electronic device 200 can be a liquid-cooled electronic device and includes a circuit board 210, a plurality of electronic components 220, and a plurality of liquid cooling pipes 230. For example, the liquid-cooled electronic device is, for example, a liquid-cooled AI server. The electronic components 220 are mounted on the circuit board 210. The electronic components 220 can be a central processing unit (CPU) and / or a graphics processing unit (GPU). The humidity sensing device 100A can be disposed on the surface 201 where the liquid cooling pipes 230 and the electronic components 220 intersect. In other embodiments, the humidity sensing device 100A can be disposed on other electronic devices adjacent to a liquid environment.

[0012] The humidity sensing device 100A includes a flexible moisture-absorbing substrate 110, a circuit layer 120A, a humidity sensing module 130A, a cover layer 141, adhesive layers 151 and 152, a conductive adhesive structure 160, an insulating moisture-absorbing adhesive layer 170, a temperature sensing module 180, and a processor (not shown). The humidity sensing device 100A can simultaneously sense humidity from both sides. That is, the humidity sensing device 100A can simultaneously sense humidity from directions D1 and D2, where directions D1 and D2 are opposite to each other. Furthermore, the humidity sensing device 100A may have a humidity sensing area 101, a transmission area 102, a bending area 103, and a temperature sensing area 104.

[0013] The flexible moisture-absorbing substrate 110 has surfaces 111 and 112 facing each other. The flexible moisture-absorbing substrate 110 can absorb water or moisture, thereby changing its dielectric constant. The material of the flexible moisture-absorbing substrate 110 can be polyimide (PI), wherein the dielectric constant of polyimide is 3.4 at a frequency of 1 kHz, and the water absorption rate is in the range of approximately 1.3% to 3%. The material of the flexible moisture-absorbing substrate 110 is not limited to this; it can also be other insulating materials with high water absorption rates, such as flexible substrates with a dielectric constant of 2.7 to 3.8 at a frequency of 1 kHz.

[0014] A circuit layer 120A is disposed on the surface 111 of the flexible hygroscopic substrate 110, and may be located in the transmission region 102, the bending region 103, and the temperature sensing region 104. The circuit layer 120A is used to transmit electrical signals. The material of the circuit layer 120A may be copper. The circuit layer 120A has a ground portion 121.

[0015] Figures 3A and 3B are schematic diagrams of the bent electrode structure 310 and the interdigitated electrode structure 320 of the humidity sensing module 130A in Figure 1, respectively. Referring to Figures 1, 3A, and 3B, the humidity sensing module 130A is disposed on the surface 111 of the flexible moisture-absorbing substrate 110 and located in the humidity sensing area 101. The humidity sensing module 130A is electrically connected to the circuit layer 120A. For example, the humidity sensing module 130A can be a capacitive humidity sensor and includes the bent electrode structure 310 and the interdigitated electrode structure 320.

[0016] The bent electrode structure 310 includes multiple electrodes 311, 312, 313, and 314 and two electrode connecting portions 315 and 316. The material of the bent electrode structure 310 can be copper. Further, the electrodes 311 and 312 meander along a wave-like track and are spaced apart from each other. In the example of Figure 3A, the wave-like track is a trajectory formed by moving along a forward direction (e.g., direction Y) and oscillating sequentially along a direction perpendicular to the forward direction (parallel to direction X). The wave-like track can be a square wave track or a sine wave track, without limitation. The spacing between the electrodes 311 and 312 can remain consistent.

[0017] Multiple electrodes 313 and 314 extend along direction X, wherein multiple electrodes 313 are located between multiple extension segments 312a of electrode 312, and multiple electrodes 314 are located between multiple extension segments 311a of electrode 311. Electrode connecting portions 315 and 316 are spaced apart from each other in direction X and extend along direction Y. Electrodes 311-314 are located between electrode connecting portions 315 and 316, wherein electrodes 311 and 313 are electrically connected to electrode connecting portion 315, and electrodes 312 and 314 are electrically connected to electrode connecting portion 316. The bent electrode structure 310 can be a serpentine electrode.

[0018] On the other hand, the interdigitated electrode structure 320 includes a plurality of electrodes 321, 322 and two electrode connections 323, 324. Similar to the material of the bent electrode structure 310, the interdigitated electrode structure 320 can be made of copper. Further, the plurality of electrodes 321, 322 extend at intervals along a straight direction. In the example of FIG. 3B, the plurality of electrodes 321, 322 extend along direction X. The electrode connections 323, 324 are spaced apart from each other in direction X and extend along direction Y. The plurality of electrodes 321, 322 are located between the electrode connections 323 and 324 and are arranged in an alternating pattern, wherein the plurality of electrodes 321 are electrically connected to the electrode connection 323, and the plurality of electrodes 322 are electrically connected to the electrode connection 324.

[0019] Referring to Figures 2, 3A, and 3B, electrode connection portions 315 and 323 can be electrically connected to each other, while electrode connection portions 316 and 324 can be electrically connected to each other. Specifically, the vertical projection of the bent electrode structure 310 can at least overlap with the vertical projection of the electronic component 220. That is, the bent electrode structure 310 can be disposed in the area corresponding to where the electronic component 220 is disposed. For example, the bent electrode structure 310 can cover more than 80% of the area where the electronic component 220 is disposed.

[0020] In detail, due to the shape of the bent electrode structure 310, it is advantageous to distribute it over a large area on the surface 201 of the electronic device 200, thereby increasing the effective distribution area of ​​the humidity sensing module 130A and the length of the interaction between electrodes 311 and 312. For example, when comparing the bent electrode structure 310 distributed over the same area with other electrode structures, the space utilization efficiency of the bent electrode structure 310 can be improved by 8% to 25%. Therefore, the bent electrode structure 310 is beneficial for detecting humidity over a wide range.

[0021] On the other hand, the vertical projection of the interdigitated electrode structure 320 can at least overlap with the vertical projection of the liquid cooling pipe 230. That is, the interdigitated electrode structure 320 can be disposed in the region corresponding to where the liquid cooling pipe 230 is disposed. In addition, the interdigitated electrode structure 320 can also be disposed in other regions where leakage is likely to occur. The extension direction of the electrode connection portions 323 and 324 of the interdigitated electrode structure 320 can extend along the distribution area. For example, the electrode connection portions 323 and 324 can extend along the extension direction of the liquid cooling pipe 230, and the distance D between the electrode connection portions 323 and 324 can be close to the pipe diameter Dp of the liquid cooling pipe 230, for example, the distance D can be in the range of 90% to 110% of the pipe diameter Dp.

[0022] The advantages of the interdigitated electrode structure 320 are that it reduces the influence of parasitic capacitance and resistance, thereby improving sensing accuracy, response speed, and reducing energy loss. The humidity sensing module 130A, through the combination of the bent electrode structure 310 and the interdigitated electrode structure 320, can achieve not only large-area sensing but also accurate, rapid, and real-time sensing in areas prone to leakage. In some other embodiments, the humidity sensing device 100A also includes a resistive element 192. The resistance value of the resistive element 192 can be in the range of 1MΩ to 5MΩ. The resistive element 192 can be connected in parallel between multiple electrodes 321 and multiple electrodes 322, so that the interdigitated electrode structure 320 and the resistive element 192 can form a resistor-capacitor circuit to prevent charge accumulation, reduce noise, and improve the linearity of the sensing signal.

[0023] Referring to Figures 1 and 2, the cover layer 141 covers a portion of the circuit layer 120A to protect it from oxidation and short circuits. For example, it covers the circuit layer 120A located in the transmission region 102. The cover layer 141 exposes a portion of the circuit layer 120A and the humidity sensing module 130A. For example, the cover layer 141 exposes the circuit layer 120A located in the bending region 103 and the temperature sensing region 104. That is, the cover layer 141 also exposes the conductive adhesive structure 160 and the temperature sensing module 180. The material of the cover layer 141 may be polyimide.

[0024] An adhesive layer 151 may be disposed between the surface 111 of the flexible moisture-absorbing substrate 110 and the circuit layer 120A to bond the flexible moisture-absorbing substrate 110 and the circuit layer 120A. An adhesive layer 152 may be disposed between the circuit layer 120A and the cover layer 141 to bond the circuit layer 120A and the cover layer 141. The materials of adhesive layers 151 and 152 may be glass fiber and epoxy resin. In other embodiments, the humidity sensing device 100A may not include an adhesive layer 151.

[0025] A conductive adhesive structure 160 is disposed on the surface 111 of the flexible moisture-absorbing substrate 110 and located in the bending region 103. The conductive adhesive structure 160 is electrically connected to the ground portion 121 of the circuit layer 120A. The conductive adhesive structure 160 can be both adhesive and conductive. In the example of FIG1, the humidity sensing device 100A is bent upward (direction D2) by 180 degrees in the bending region 103, so that the conductive adhesive structure 160 can be adhered to and electrically connected to the ground on the circuit board 210, thereby reducing noise interference, stabilizing signal quality, achieving electrostatic protection, reducing parasitic capacitance and resistance, and improving stability.

[0026] In other embodiments, the humidity sensing device 100A may be oriented in other directions and bent at other suitable angles in the bending region 103 to electrically connect the ground on the circuit board 210 via the conductive adhesive structure 160. The conductive adhesive structure 160 may be made of conductive pressure-sensitive adhesive, conductive foam, or other conductive adhesives, and is not limited thereto.

[0027] An insulating moisture-absorbing adhesive layer 170 is disposed on the surface 112 of the flexible moisture-absorbing substrate 110. The humidity sensing device 100A can be attached to the surface 201 of the electronic device 200 via the insulating moisture-absorbing adhesive layer 170. The insulating moisture-absorbing adhesive layer 170 can absorb water or moisture, thereby allowing liquid to pass through its structure. The material of the insulating moisture-absorbing adhesive layer 170 can be epoxy resin, wherein the epoxy resin has a dielectric constant of 3.5 to 6 at a frequency of 1 kHz and a water absorption rate in the range of approximately 0.1% to 2%. The material of the insulating moisture-absorbing adhesive layer 170 is not limited to this; it can also be other insulating substrates with adhesiveness and high water absorption rate. For example, the insulating moisture-absorbing adhesive layer 170 can be a pressure-sensitive adhesive.

[0028] A temperature sensing module 180 is disposed on the surface 111 of the flexible moisture-absorbing substrate 110 and located in the temperature sensing region 104. The temperature sensing module 180 is electrically connected to the circuit layer 120A. The temperature sensing module 180 is used to sense the ambient temperature. In the example of FIG1, the temperature sensing module 180 may be a microelectromechanical system (MEMS) temperature sensor and includes a reinforcement 181, wherein the reinforcement 181 protrudes from the surface 112 and the insulating moisture-absorbing adhesive layer 170. The temperature sensing module 180 may be mounted on the circuit layer 120A via surface mount assembly (SMT) technology. The temperature sensing module 180 can sense the temperature not only on the side of surface 111, but also on the side of surface 112 via the reinforcement 181.

[0029] A processor (not shown) may be located in transmission area 102 or other suitable area. The processor may be electrically connected to line layer 120A, humidity sensing module 130A, and temperature sensing module 180 to process sensing signals transmitted from humidity sensing module 130A and temperature sensing module 180. In other embodiments, the processor may also receive sensing signals from electronic device 200 for signal comparison or integration, such as temperature sensing signals from central processing unit and / or graphics processing unit. In other embodiments, the processor may be mounted on electronic device 200 for integration into electronic device 200.

[0030] Furthermore, the humidity sensing device 100A may also include a plating layer 190. For example, a surface finish, such as electroless nickel immersion gold (ENIG), tin plating, or electroplating, can be applied to the humidity sensing module 130A and the exposed circuit layer 120A (located in the bending area 103 and the temperature sensing area 104) of the cover layer 141 to form the plating layer 190, thereby preventing the humidity sensing module 130A and the circuit layer 120A from oxidizing with air and ensuring effective soldering. Therefore, the plating layer 190 can cover the humidity sensing module 130A, and the area between the conductive bonding structure 160 and the ground portion 121, and between the temperature sensing module 180 and the circuit layer 120A.

[0031] It should be noted that the line layer 120A in the transmission area 102 may also have a resistive part, so that when the humidity sensing device 100A is operating, the temperature is increased through the resistive part, thereby accelerating the sensing speed of the humidity sensing module 130A.

[0032] Referring to Figures 1, 2, 3A, and 3B, when the humidity sensing device 100A senses humidity, liquid leakage generated by the electronic device 200 can pass through the insulating moisture-absorbing adhesive layer 170 from direction D1 to the flexible moisture-absorbing substrate 110. The flexible moisture-absorbing substrate 110 then absorbs the liquid, thereby changing the capacitance values ​​between electrode connections 315 and 316, and between electrode connections 323 and 324, to sense humidity from direction D1. Furthermore, the humidity sensing module 130A can also directly sense ambient humidity from direction D2. Therefore, the humidity sensing device 100A can simultaneously sense humidity from both directions D1 and D2. Moreover, compared to existing humidity sensors using silicon substrates, the humidity sensing device 100A is not only thinner but also easier to bend, thus allowing for stable attachment to the electronic device 200.

[0033] Figure 4 is a cross-sectional view of a humidity sensing device 100B disposed in an electronic device 200 according to another embodiment of this application. Referring to Figure 4, the humidity sensing device 100B is similar to the humidity sensing device 100A in Figure 1. The difference between the humidity sensing device 100B and the humidity sensing device 100A is that the humidity sensing device 100B further includes a circuit layer 120B, a humidity sensing module 130B, a cover layer 142, adhesive layers 153 and 154, and a conductive structure 400.

[0034] The circuit layer 120B can be stacked on the surface 112 of the flexible moisture-absorbing substrate 110 via the adhesive layer 153. The humidity sensing module 130B can be disposed on the surface 112 of the flexible moisture-absorbing substrate 110, and is also located in the humidity sensing area 101 opposite to the humidity sensing module 130A. The humidity sensing module 130B is electrically connected to the circuit layer 120B. The humidity sensing module 130B can also be a capacitive humidity sensor, and includes a bent electrode structure 310 and an interdigitated electrode structure 320 (as shown in Figures 3A and 3B). The conductive structure 400 extends from the circuit layer 120A to the circuit layer 120B, and is electrically connected to the circuit layers 120A and 120B.

[0035] Cover layer 142 covers a portion of the circuit layer 120B. Adhesive layer 154 may be disposed between the circuit layer 120B and the cover layer 142 to bond the circuit layer 120B and the cover layer 142. Furthermore, adhesive layer 154 may also fill the hollow space within the conductive structure 400. In other embodiments, the humidity sensing device 100B may not include adhesive layers 151 and 153. Further, conductive adhesive structure 160 is disposed on the surface 112 of the flexible moisture-absorbing substrate 110. Conductive adhesive structure 160 is electrically connected to the ground portion 122 of the circuit layer 120B and electrically connected to the ground portion 121 of the circuit layer 120A. That is, the ground portions 121 and 122 of the circuit layers 120A and 120B are mutually conductive.

[0036] In the example of Figure 4, the humidity sensing device 100B is not bent in the bending area 103, and the conductive adhesive structure 160 can be directly bonded to and electrically connected to the ground on the circuit board 210 in direction D2, but this is not a limitation. In other embodiments, the humidity sensing device 100B can still be bent at a suitable angle in the bending area 103, making it easier for the conductive adhesive structure 160 to bond to the ground on the circuit board 210. In addition, the insulating moisture-absorbing adhesive layer 170 is disposed on the surface 112 of the flexible moisture-absorbing substrate 110 and is located on the cover layer 142 and the humidity sensing module 130B. The humidity sensing device 100B can sense the humidity in directions D2 and D1 respectively through the humidity sensing modules 130A and 130B, thereby avoiding mutual interference between the signals from the humidity in directions D2 and D1.

[0037] It is worth mentioning that, in other embodiments, a fluorine layer is stacked between the flexible moisture-absorbing substrate 110 and the circuit layer 120A, so that the humidity sensing device 100A reduces the humidity influence on one side through the fluorine layer with low water absorption rate. In other embodiments, multiple pores are distributed in the flexible moisture-absorbing substrate 110, or a non-conductive nano-coating is coated on the surface of the flexible moisture-absorbing substrate 110 and the humidity sensing module 130A, so that the humidity sensing device 100A improves the humidity sensing sensitivity by increasing the surface area of ​​the flexible moisture-absorbing substrate 110. In other embodiments, the flexible moisture-absorbing substrate 110 can be replaced by a double-layer flexible moisture-absorbing modified substrate and a fluorine layer stacked between the double-layer flexible moisture-absorbing modified substrate, thereby reducing the mutual influence of humidity in both directions of the humidity sensing device 100B. Through the above, the humidity sensing devices 100A and 100B can be adaptively adjusted according to the actual installation environment.

[0038] The manufacturing method of the humidity sensing device 100A in Figure 1 is described below. Figures 5, 6, 7, and 8 are cross-sectional schematic diagrams of the steps in the manufacturing method of the humidity sensing device 100A in Figure 1, namely, providing a flexible substrate 500, forming a circuit layer 120A and a humidity sensing module 130A, setting a cover layer 141 and forming a plating layer 190, and setting a conductive adhesive structure 160, an insulating moisture-absorbing adhesive layer 170, and a temperature sensing module 180. Referring to Figure 5, a flexible substrate 500 is provided, wherein the flexible substrate 500 includes a flexible moisture-absorbing substrate 110, an adhesive layer 151, and a metal layer 510. The adhesive layer 151 is located between the flexible moisture-absorbing substrate 110 and the metal layer 510 to bond the flexible moisture-absorbing substrate 110 and the metal layer 510. The material of the metal layer 510 may be copper. In other embodiments, the flexible substrate 500 may not include the adhesive layer 151.

[0039] Referring to Figures 5 and 6, next, a patterned metal layer 510 is formed to create a circuit layer 120A and a humidity sensing module 130A, wherein the circuit layer 120A is electrically connected to the humidity sensing module 130A. The patterned metal layer 510 can be fabricated using lithography and etching processes. Referring to Figures 6 and 7, first, a cover layer 141 is formed. The cover layer 141 can be patterned and then bonded to a portion of the circuit layer 120A via an adhesive layer 152, or the unpatterned cover layer 141 can be bonded to the circuit layer 120A first, and then patterned (exposed and developed). Next, the remaining portion of the circuit layer 120A without the cover layer 141 is surface-treated to form a plating layer 190. Referring to Figures 7 and 8, next, a conductive adhesive structure 160, an insulating moisture-absorbing adhesive layer 170, a temperature sensing module 180, and a resistive element 192 are formed. A conductive bonding structure 160 is disposed on the ground portion 121 of the circuit layer 120A. A resistive element 192 is connected in parallel to electrodes 321 and 322 of the interdigitated electrode structure 320. Thus, the manufacturing of the humidity sensing device 100A is essentially completed.

[0040] The manufacturing method of the humidity sensing device 100B in Figure 4 is described below. Figures 9, 10, 11, and 12 are cross-sectional schematic diagrams of the steps in the manufacturing method of the humidity sensing device 100B in Figure 4, including providing a flexible substrate 600, forming a conductive structure 400, forming circuit layers 120A and 120B and humidity sensing modules 130A and 130B, and setting cover layers 141 and 142 and forming a plating layer 190. Referring to Figure 9, a flexible substrate 600 is provided, which includes a flexible moisture-absorbing substrate 110, adhesive layers 151 and 153, and metal layers 610 and 620. The flexible moisture-absorbing substrate 110 and the metal layers 610 and 620 are stacked. The adhesive layers 151 and 153 are located between the flexible moisture-absorbing substrate 110 and the metal layer 610, and between the flexible moisture-absorbing substrate 110 and the metal layer 620, respectively, to bond the flexible moisture-absorbing substrate 110 and the metal layers 610 and 620. The metal layers 610 and 620 may be made of copper. In other embodiments, the flexible substrate 600 may not include adhesive layers 151 and 153.

[0041] Referring to Figures 9 and 10, firstly, a hole is drilled in the flexible substrate 600 to form a through-hole 630. Next, the inner wall surface of the through-hole 630 is metallized to form a conductive structure 400, for example, by forming a metal layer on the inner wall surface of the through-hole 630 using plating through-hole (PTH) plating. The conductive structure 400 extends from the metal layer 610 to the metal layer 620 and is electrically connected to the metal layers 610 and 620. Referring to Figures 10 and 11, next, the metal layers 610 and 620 are patterned to form circuit layers 120A and 120B and humidity sensing modules 130A and 130B, respectively. The circuit layers 120A and 120B are electrically connected to the humidity sensing modules 130A and 130B, respectively, and the conductive structure 400 is electrically connected to the circuit layers 120A and 120B. The patterned metal layers 610 and 620 can also be completed by lithography and etching processes.

[0042] Referring to Figures 11 and 12, similar to the steps in Figure 7, firstly, cover layers 141 and 142 are provided on portions of the circuit layers 120A and 120B. The cover layers 141 and 142 are attached to portions of the circuit layers 120A and 120B via adhesive layers 152 and 154, and the adhesive layer 154 fills the through-hole 630. Next, the remaining portions of the circuit layers 120A and 120B without cover layers 141 and 142 are surface-treated to form a plating layer 190. Next, a conductive adhesive structure 160, an insulating moisture-absorbing adhesive layer 170, a temperature sensing module 180, and a resistive element 192 are provided. The conductive adhesive structure 160 is provided at the ground portion 122 of the circuit layer 120B. Thus, the manufacturing of the humidity sensing device 100B (Figure 4) is essentially completed.

[0043] In summary, in the humidity sensing device disclosed in the above embodiments, the flexible hygroscopic substrate can absorb humidity in two opposing directions, enabling the humidity sensing device to simultaneously sense humidity on both sides. Furthermore, the flexible hygroscopic substrate makes it easier to stably attach the humidity sensing device to electronic devices. In addition, the combination of the bent electrode structure and the interdigitated electrode structure allows for large-area sensing, as well as accurate, rapid, and real-time sensing in areas prone to leakage. Moreover, the conductive adhesive structure facilitates electrical connection with the grounding of electronic devices, thereby reducing noise interference, stabilizing signal quality, providing electrostatic protection, reducing parasitic capacitance and resistance, and improving stability.

[0044] Although this application has been disclosed above with reference to embodiments, it is not intended to limit this application. Those skilled in the art to which this application pertains may make some modifications and refinements without departing from the spirit and scope of this application. Therefore, the scope of protection of this application shall be determined by the appended claims.

[0045] 100A, 100B: Humidity sensing devices 101: Humidity sensing area 102: Transmission Area 103: Bending area 104: Temperature sensing area 110: Flexible moisture-absorbing substrate 111,112,201: Surface 120A, 120B: Line Layer 121, 122: Grounding part 130A, 130B: Humidity sensing module 141, 142: Overlay 151, 152, 153, 154: Adhesive layer 160: Conductive adhesive structure 170: Insulating and moisture-absorbing adhesive layer 180: Temperature sensing module 181: Reinforcing component 190: Coating 192: Resistive element 200: Electronic devices 210: Circuit board 220: Electronic Components 230: Liquid cooling pipe 310: Bending electrode structure 311, 312, 313, 314, 321, 322: Electrodes 311a, 312a: Extensions 315, 316, 323, 324: Electrode connection parts 320: Interdigitated electrode structure 400: Conductive structure 500, 600: Flexible substrate 510, 610, 620: Metal layer 630: Through hole D: Distance D1, D2, X, Y: Direction Dp: Pipe diameter

Claims

1. A humidity sensing device, comprising: a flexible moisture-absorbing substrate having a first surface and a second surface opposite to each other; a first circuit layer disposed on the first surface and having a first ground portion; a first humidity sensing module disposed on the first surface and electrically connected to the first circuit layer, wherein the first humidity sensing module is a capacitive humidity sensor; a conductive adhesive structure disposed on the flexible moisture-absorbing substrate and electrically connected to the first ground portion; and an insulating moisture-absorbing adhesive layer disposed on the second surface.

2. The humidity sensing device as claimed in claim 1, wherein the conductive adhesive structure is disposed on the first surface and located in a bending region of the humidity sensing device; wherein the humidity sensing device further comprises: a first cover layer covering the first circuit layer and exposing the first humidity sensing module and the conductive adhesive structure.

3. The humidity sensing device as claimed in claim 1, wherein the first humidity sensing module comprises: a bent electrode structure including a first electrode, a second electrode, a first electrode connection portion and a second electrode connection portion, wherein the first electrode and the second electrode meander along a wave track and are separated from each other, the first electrode connection portion and the second electrode connection portion are spaced apart from each other, the first electrode is electrically connected to the first electrode connection portion, the second electrode is electrically connected to the second electrode connection portion, and the first electrode and the second electrode are located between the first electrode connection portion and the second electrode connection portion; An interdigitated electrode structure includes a plurality of third electrodes, a plurality of fourth electrodes, a third electrode connection portion, and a fourth electrode connection portion, wherein the plurality of third electrodes and the plurality of fourth electrodes extend along a straight line at intervals, the third electrode connection portion and the fourth electrode connection portion are spaced apart from each other, the plurality of third electrodes are electrically connected to the third electrode connection portion, the plurality of fourth electrodes are electrically connected to the fourth electrode connection portion, the plurality of third electrodes and the plurality of fourth electrodes are located between the third electrode connection portion and the fourth electrode connection portion, and are arranged alternately at intervals; and a resistive element is connected in parallel between the plurality of third electrodes and the plurality of fourth electrodes; wherein the first electrode connection portion is electrically connected to the third electrode connection portion, and the second electrode connection portion is electrically connected to the fourth electrode connection portion.

4. The humidity sensing device as claimed in claim 3, wherein the humidity sensing device is disposed in an electronic device, and the second surface faces the electronic device, the flexible hygroscopic substrate is used to absorb liquid from the electronic device, the electronic device includes an electronic component and a liquid cooling pipe; wherein the vertical projection of the bent electrode structure overlaps at least with the vertical projection of the electronic component; wherein the vertical projection of the interdigitated electrode structure overlaps at least with the vertical projection of the liquid cooling pipe, and a distance from the third electrode connection to the fourth electrode connection approaches a diameter of the liquid cooling pipe.

5. The humidity sensing device as claimed in claim 1, wherein the humidity sensing device further comprises: a second circuit layer disposed on the second surface and having a second ground portion; a second humidity sensing module disposed on the second surface and electrically connected to the second circuit layer; and a conductive structure extending from the first circuit layer to the second circuit layer and electrically connected to the first circuit layer and the second circuit layer; wherein the conductive bonding structure is disposed on the second surface and electrically connected to the second ground portion.

6. The humidity sensing device as claimed in claim 5 further comprises: a first overlay layer covering the first circuit layer and exposing the first humidity sensing module; and a second overlay layer covering the second circuit layer and exposing the second humidity sensing module and the conductive adhesive structure.

7. The humidity sensing device as claimed in claim 1 further comprises: a temperature sensing module disposed on the first surface and electrically connected to the first circuit layer.

8. A method for manufacturing a humidity sensing device, comprising: providing a flexible substrate, wherein the flexible substrate includes a flexible moisture-absorbing substrate and a metal layer, and the flexible moisture-absorbing substrate and the metal layer are stacked; patterning the metal layer to form a circuit layer and a humidity sensing module, wherein the circuit layer is electrically connected to the humidity sensing module, and the humidity sensing module is a capacitive humidity sensor; disposing a conductive adhesive structure at a ground portion of the circuit layer; and disposing an insulating moisture-absorbing adhesive layer on the flexible moisture-absorbing substrate, wherein the flexible moisture-absorbing substrate is located between the insulating moisture-absorbing adhesive layer and the humidity sensing module.

9. A method for manufacturing a humidity sensing device, comprising: providing a flexible substrate, wherein the flexible substrate includes a flexible moisture-absorbing substrate, a first metal layer and a second metal layer, the flexible moisture-absorbing substrate, the first metal layer and the second metal layer being stacked, and the flexible moisture-absorbing substrate being located between the first metal layer and the second metal layer; forming a conductive structure, wherein the conductive structure extends from the first metal layer to the second metal layer and is electrically connected to the first metal layer and the second metal layer; patterning the first metal layer to form a first circuit layer and a first humidity sensing module, wherein the first circuit layer is electrically connected to the first humidity sensing module, and the first humidity sensing module is a capacitive humidity sensor; patterning the second metal layer to form a second circuit layer and a second humidity sensing module, wherein the second circuit layer is electrically connected to the second humidity sensing module, and the conductive structure is electrically connected to the first circuit layer and the second circuit layer, and the second humidity sensing module is a capacitive humidity sensor. After forming the second circuit layer, a conductive adhesive structure is provided on a ground portion of the second circuit layer; and an insulating moisture-absorbing adhesive layer is provided on the flexible moisture-absorbing substrate, wherein the second humidity sensing module is located between the insulating moisture-absorbing adhesive layer and the flexible moisture-absorbing substrate.

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