Pressure sensing circuit board and manufacturing method thereof

Abstract

The application discloses a pressure sensing circuit board (100), which comprises a dielectric layer (12), a circuit layer (145), a strain layer (30) and a protective layer (40), wherein the circuit layer (145) is located on the surface of the dielectric layer (12); the strain layer (30) is located on the surface of the dielectric layer (12) on the same side as the circuit layer (145); and the protective layer (40) is located on the surface of the circuit layer (145) and the strain layer (30). The pressure sensing circuit board (100) comprises a first copper area (I), a second copper area (II) and a non-copper area (III) connected in sequence; the circuit layer (145) is located in the first copper area (I) and the second copper area (II) along the stacking direction of the circuit layer (145) and the dielectric layer (12), the thickness of the circuit layer (145) located in the first copper area (I) is greater than the thickness of the circuit layer (145) located in the second copper area (II), and the circuit layer (145) located in the second copper area (II) is in a grid shape; the strain layer (30) is located in the non-copper area (III) and connected with the circuit layer (145); and the protective layer (40) is located on the surface of the circuit layer (145) in the second copper area (II) and covers the strain layer (30). The application further provides a manufacturing method of the pressure sensing circuit board (100).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pressure sensors, in particular to a pressure sensing circuit board and a manufacturing method thereof. BACKGROUND

[0002] With the development of intelligent life, intelligent devices are applied in various fields, such as communication field, medical field, automobile field, industrial control field, etc., and the use of pressure sensors is indispensable for intelligent devices.

[0003] The existing pressure sensors include capacitive pressure sensors, resistive pressure sensors, and piezoelectric ceramic pressure sensors. The capacitive pressure sensors require high processing precision; the resistive pressure sensors have poor linearity and poor durability; the piezoelectric ceramic pressure sensors require high-temperature sintering and have a large manufacturing process difficulty, and can only test instantaneous pressure, and both upper and lower surfaces of the above pressure sensors need to be supported. SUMMARY

[0004] Therefore, it is necessary to provide a pressure sensing circuit board capable of solving the above technical problems.

[0005] In addition, it is also necessary to provide a manufacturing method of the pressure sensing circuit board.

[0006] A pressure sensing circuit board comprises a dielectric layer, a circuit layer, a strain layer, and a protective layer. The circuit layer is located on the surface of the dielectric layer. The strain layer is located on the surface of the dielectric layer on the same side as the circuit layer. The protective layer is located on the surface of the circuit layer and the strain layer. The pressure sensing circuit board comprises a first copper area, a second copper area, and a non-copper area connected in sequence. The circuit layer is located in the first copper area and the second copper area. In the stacking direction of the circuit layer and the dielectric layer, the thickness of the circuit layer located in the first copper area is greater than the thickness of the circuit layer located in the second copper area. The circuit layer located in the second copper area is in a grid shape. The strain layer is located in the non-copper area and connected with the circuit layer. The protective layer is located on the surface of the circuit layer in the second copper area and covers the strain layer.

[0007] In some embodiments, the grid-shaped circuit layer comprises at least one of staggered mesh format circuit, non-staggered corrugated circuit, and horseshoe type circuit.

[0008] In some embodiments, in the stacking direction of the circuit layer and the dielectric layer, the thickness of the strain layer is greater than the thickness of the circuit layer located in the second copper area.

[0009] In some embodiments, the strain layer is also located in the second copper area and covers part of the surface of the circuit layer located in the second copper area. The second copper area and the strain layer form an overlapping structure with the circuit layer.

[0010] In some embodiments, the pressure sensing circuit board further comprises three resistors with fixed resistance values, and the three resistors and the strain layer form a Wheatstone bridge.

[0011] In some embodiments, the pressure sensing circuit board further comprises an insulating layer covering the surface of the circuit layer in the first copper area.

[0012] In some embodiments, the method comprises the following steps: providing a copper-clad substrate, which comprises a dielectric layer and a copper layer on the surface of the dielectric layer; performing a partial copper removal treatment on the copper layer to form a second copper area and a first copper area; removing part of the copper layer in the second copper area to form a copper-free area, so that part of the dielectric layer is exposed; performing circuit fabrication on the copper layer to form a circuit layer, wherein the remaining copper layer in the second copper area is subjected to a meshing treatment to form a mesh-shaped circuit layer; forming a strain layer on the surface of the dielectric layer in the copper-free area; and forming a protective layer on the surface of the circuit layer in the second copper area, wherein the protective layer also covers the strain layer, thereby forming the pressure sensing circuit board.

[0013] In some embodiments, the thickness of the strain layer is greater than the thickness of the circuit layer in the second copper area along the stacking direction of the copper layer and the dielectric layer.

[0014] In some embodiments, in the step of forming the strain layer, the strain layer also covers the surface of the circuit layer adjacent to the second copper area.

[0015] In some embodiments, after the step of forming the circuit layer, the method further comprises: forming an insulating layer on the surface of the circuit layer in the first copper area.

[0016] The pressure sensing circuit board provided in the present application comprises a circuit layer on the surface of a dielectric layer and a strain layer. When the strain layer is subjected to an external force, the resistance of the strain layer changes, thereby changing the resistance of the pressure sensing circuit board in an electrical circuit. When the resistance changes, the voltage monitored in the electrical circuit changes, and the size of the external force acting on the strain layer can be calculated according to the voltage change. The resistance of the strain layer changes linearly when the strain layer is subjected to an external force, and the resistance value returns to normal when the external force is removed. Therefore, the size of the external force acting on the strain layer at any time can be tested, and the linearity is good. The durability of the pressure sensing circuit board is improved by the protective layer on the strain layer. The strain capacity of the circuit layer is improved by the mesh-shaped circuit layer in the second copper area, thereby improving the sensitivity of the pressure sensing circuit board. The structure of the pressure sensing circuit board is simplified by arranging the dielectric layer on one side of the circuit layer, the strain layer and the protective layer. The pressure sensing circuit board is easy to manufacture. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application.

[0018] Figure 2 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application. Figure 1 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application.

[0019] Figure 3 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application. Figure 2 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application.

[0020] Figure 4 A top view of an interleaved mesh patterned circuit layer according to an embodiment of the present application.

[0021] Figure 5 A top view of a non-interleaved corrugated patterned circuit layer according to another embodiment of the present application.

[0022] Figure 6 A top view of a horseshoe patterned circuit layer according to another embodiment of the present application.

[0023] Figure 7 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application. Figure 3 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application.

[0024] Figure 8 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application. Figure 7 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application.

[0025] Figure 9 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application. Figure 8 A cross-sectional view of a copper clad substrate including a dielectric layer and a copper layer according to an embodiment of the present application.

[0026] Figure 10 A connection diagram of a Wheatstone bridge formed by the strain layer according to an embodiment of the present application.

[0027] Explanation of main component symbols

[0028]

[0029] The following detailed description will further describe the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0030] In order to enable a clearer understanding of the above-mentioned objects, features and advantages of the present application, the present application will be described in detail below with reference to the drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict. In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application. The described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work under the premise that there is no conflict, fall within the scope of protection of the present application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the term "and / or" includes all and any combination of one or more of the associated listed items.

[0032] In the embodiments of the present application, for the purpose of description but not limitation of the present application, the term "connection" used in the patent application specification and claims of the present application is not limited to physical or mechanical connection, whether direct or indirect. "Up", "down", "above", "below", "left", "right" and the like are only used to indicate relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0033] Referring to Figures 1 to 10 , the present embodiment provides a manufacturing method of a pressure sensing circuit board 100, comprising the following steps:

[0034] Step S1: referring to Figure 1 , a copper-clad substrate 10 is provided, comprising a dielectric layer 12 and a copper layer 14 located on the surface of the dielectric layer 12.

[0035] The material of the dielectric layer 12 can be rigid material or flexible material. The material of the dielectric layer 12 can include but is not limited to polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate two formic acid glycolester (PEN), liquid crystal polymer (LCP) and modified polyimide (MPI), etc.

[0036] The copper layer 14 can be located on one surface of the dielectric layer 12 or on opposite surfaces of the dielectric layer 12. In the embodiment, the copper layer 14 is located on one surface of the dielectric layer 12.

[0037] In some modes, an inner buried circuit layer (not shown) electrically connected with the copper layer 14 can also be embedded in the dielectric layer 12, so that the prepared pressure sensing circuit board 100 has a multi-layer circuit layer.

[0038] Step S2: please refer to Figure 2 The copper layer 14 is subjected to local copper reduction treatment to form a second copper region II and a first copper region I.

[0039] Part of the copper layer 14 is removed, so that the thickness of the copper layer 14 in some areas is thinned, and the thickness of the copper layer 14 in other areas remains unchanged. The area where the thickness of the copper layer 14 is thinned is the second copper region II, and the area where the thickness of the copper layer 14 remains unchanged is the first copper region I.

[0040] Step S3: please refer to Figures 3 to 6 Part of the copper layer 14 located in the second copper region II is removed to form a copper-free region III, so that part of the dielectric layer 12 is exposed. The copper layer 14 is subjected to circuit production to form a circuit layer 145. In this process, the remaining copper layer 14 located in the second copper region II is subjected to grid processing to form a grid-shaped circuit layer 145.

[0041] It can be understood that the surface of the dielectric layer 12 located in the copper-free region III is not provided with the copper layer 14.

[0042] The copper-free region III and the first copper region I are spaced apart by the second copper region II. The surfaces of the first copper region I, the second copper region II, and the copper-free region III form a stepped shape in sequence, that is, along the stacking direction of the copper layer 14 and the dielectric layer 12, the thickness of the copper layer 14 located in the first copper region I is greater than the thickness of the copper layer 14 located in the second copper region II.

[0043] The remaining copper layer 14 located in the second copper region II is subjected to grid processing. Part of the copper layer 14 located in the second copper region II is thinned or removed again to form a grid shape. In the embodiment, part of the copper layer 14 located in the second copper region II is removed, and the surface of the dielectric layer 12 is exposed.

[0044] The grid-shaped circuit layer 145 formed by the grid processing can be connected or not connected to each other, including but not limited to staggered mesh circuit (please refer to Figure 4 ), non-staggered corrugated circuit (please refer to Figure 5) and horse-shoe type line (see Figure 6 The grid-shaped line layer 145 is easier to deform when subjected to external force, thereby improving the strain capability of the line layer 145.

[0045] Step S4: see Figure 7 An insulating layer 20 is formed on the first copper area I to cover the line layer 145.

[0046] The insulating layer 20 is used to prevent the line layer 145 from being oxidized.

[0047] Step S5: see Figure 8 A strain layer 30 is formed on the surface of the dielectric layer 12 of the copper-free area III.

[0048] The strain layer 30 is made of a material that deforms when subjected to external force, thereby changing the resistance, including but not limited to metal, carbon-containing conductive resin, etc.

[0049] In the process of forming the strain layer 30, the thickness of the strain layer 30 is greater than the thickness of the copper layer 14 of the second copper area II. Due to the fluidity of the strain layer 30, the strain layer 30 also covers the surface of the line layer 145 adjacent to the second copper area II. The strain layer 30 covers at least part of the line layer 145 in the second copper area II, i.e., the strain layer 30 and the line layer 145 form an overlapping structure, increasing the contact area between the strain layer 30 and the line layer 145, improving the connection reliability, and avoiding poor contact.

[0050] In some embodiments, before forming the strain layer 30, a step of forming a treatment layer on the surface of the line layer 145 is further included to prevent the line layer 145 from being oxidized.

[0051] Step S6: see Figure 9 A protective layer 40 is formed on the surface of the line layer 145 of the second copper area II, and the protective layer 40 also covers the strain layer 30, thereby forming the pressure sensing circuit board 100.

[0052] The protective layer 40 is made of an insulating ink layer, which has good ductility and will not crack when subjected to external force.

[0053] In some embodiments, the step of forming the insulating layer 20 can be after the steps of forming the strain layer 30 and / or the protective layer 40.

[0054] See Figure 10The pressure sensing circuit board 100 further comprises three resistors R1, R2 and R3 with fixed resistance values, the resistor R1 is connected in series with the resistor R2, the resistor R3 is connected in series with the resistor Rx composed of the strain layer 30, and then the series-connected resistor R1 and resistor R2 are connected in parallel with the series-connected resistor R3 and resistor Rx, thereby forming a Wheatstone bridge, and the entire circuit loop is constructed by using the characteristics of the bridge, so that the pressure sensing circuit board 100 can work more sensitively and effectively.

[0055] Specifically, when the resistance Rx composed of the strain layer 30 changes, the voltage between points B and D in the figure changes, and by collecting the change of the voltage, the change amount of the resistance Rx can be calculated, and thus the size of the external force acting on the strain layer 30 can be calculated.

[0056] Please refer again to Figure 10 The application further provides a pressure sensing circuit board 100, which comprises a dielectric layer 12, a circuit layer 145, a strain layer 30 and a protective layer 40. The circuit layer 145 is located on the surface of the dielectric layer 12; the strain layer 30 is located on the surface of the dielectric layer 12 on the same side as the circuit layer 145; and the protective layer 40 is located on the surface of the circuit layer 145 and the strain layer 30.

[0057] The pressure sensing circuit board 100 comprises a first copper area I, a second copper area II and a non-copper area III connected in sequence; the circuit layer 145 is located in the first copper area I and the second copper area II, and the thickness of the circuit layer 145 located in the first copper area I is greater than the thickness of the circuit layer 145 located in the second copper area II along the stacking direction of the circuit layer 145 and the dielectric layer 12, and the circuit layer 145 located in the second copper area II is in a grid shape; the strain layer 30 is located in the non-copper area III and connected with the circuit layer 145; and the protective layer 40 is located on the surface of the circuit layer 145 in the second copper area II and covers the strain layer 30.

[0058] When the protective layer 40 is subjected to an external force, the external force is transmitted to the strain layer 30, the strain layer 30 generates strain under the action of the external force, the resistance of the strain layer 30 changes, and thus the resistance of the pressure sensing circuit board 100 in the electrical circuit changes. When the resistance changes, the monitored voltage in the electrical circuit changes, and the size of the external force acting on the strain layer 30 can be calculated according to the size of the voltage change.

[0059] The material of the medium layer 12 can be rigid or flexible. The material of the medium layer 12 can include, but is not limited to, polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate two formic acid glycolester (PEN), liquid crystal polymer (LCP), and modified polyimide (MPI), etc. In some embodiments, the material of the medium layer 12 is flexible, so that the pressure sensing circuit board 100 is flexible and can be bent at a suitable position to meet different user needs.

[0060] The grid-shaped circuit layer 145 can be connected or not connected to each other, including but not limited to at least one of staggered mesh circuit, non-staggered corrugated circuit, and horseshoe-shaped circuit. The formation of the grid-shaped circuit layer 145 is more likely to deform when subjected to external force, thereby facilitating the improvement of the strain capacity of the circuit layer 145.

[0061] In some embodiments, the thickness of the strain layer 30 is greater than the thickness of the circuit layer 145 located in the second copper area II along the stacking direction of the circuit layer 145 and the medium layer 12, so that at least part of the strain layer 30 covers at least part of the circuit layer 145 located in the second copper area II, i.e., the strain layer 30 and the circuit layer 145 form an overlapping structure, increase the contact area between the strain layer 30 and the circuit layer 145, improve the connection reliability, and avoid poor contact.

[0062] In some embodiments, the strain layer 30 is also located in the second copper area II and covers part of the surface of the circuit layer 145 located in the second copper area II, and the strain layer 30 and the circuit layer 145 located in the second copper area II form an overlapping structure.

[0063] The protective layer 40 is located on the surface of the circuit layer 145 and the strain layer 30. On the one hand, the protective layer 40 is used to protect the circuit layer 145 from oxidation; on the other hand, the protective layer 40 also has ductility, so that the protective layer 40 will not crack when subjected to external force.

[0064] In some embodiments, the pressure sensing circuit board 100 further includes an insulating layer 20 covering the surface of the circuit layer 145 located in the first copper area I for protecting the circuit layer 145.

[0065] Please refer to Figure 10 , the pressure sensing circuit board 100 further comprises three resistors R1, R2 and R3 with fixed resistance values, the resistor R1 is connected in series with the resistor R2, the resistor R3 is connected in series with the resistor Rx composed of the strain layer 30, and then the series-connected resistor R1 and R2 are connected in parallel with the series-connected resistor R3 and Rx, thereby forming a Wheatstone bridge, and the entire circuit loop is constructed by using the characteristics of the bridge, so that the pressure sensing circuit board 100 can work more sensitively and effectively.

[0066] The pressure sensing circuit board 100 provided by the application has the advantages that: the linear change of the resistance of the strain layer 30 when the strain layer 30 is subjected to an external force and the recovery of the resistance value when the external force is lost can be used to test the size of the external force received at any time period, and the linearity is good; the durability of the pressure sensing circuit board 100 is improved by the arrangement of the protective layer 40 on the strain layer 30; the strain capacity of the circuit layer 145 is improved by arranging the grid-shaped circuit layer 145 in the second copper area II of the pressure sensing circuit board 100, thereby improving the sensitivity of the pressure sensing circuit board 100; the structure of the pressure sensing circuit board 100 is simplified by arranging the dielectric layer 12 on one side of the circuit layer 145, the strain layer 30 and the protective layer 40; and the manufacturing method of the pressure sensing circuit board 100 is simple.

[0067] The above embodiments are only used to illustrate the technical solutions of the application rather than limit the application, and although the application has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the application.

Claims

1. A pressure sensing circuit board, characterized by, The pressure sensing circuit board comprises: a medium layer; a circuit layer on a surface of the medium layer; a strain layer on a surface of the medium layer on the same side as the circuit layer; and a protective layer on surfaces of the circuit layer and the strain layer. The pressure sensing circuit board comprises a first copper area, a second copper area and a non-copper area connected in sequence. The circuit layer is located on the first copper area and the second copper area. In the stacking direction of the circuit layer and the medium layer, the thickness of the circuit layer located on the first copper area is greater than the thickness of the circuit layer located on the second copper area. The circuit layer located on the second copper area is in a grid shape. The strain layer is located on the non-copper area and connected with the circuit layer. The protective layer is located on the surface of the circuit layer of the second copper area and covers the strain layer. The grid-shaped circuit layer comprises at least one of staggered mesh circuit, non-staggered corrugated circuit and horseshoe-shaped circuit.

2. The pressure sensing circuit board of claim 1, wherein, In the stacking direction of the circuit layer and the medium layer, the thickness of the strain layer is greater than the thickness of the circuit layer located on the second copper area.

3. The pressure sensing circuit board of claim 1, wherein, The strain layer is also located on the second copper area and covers part of the surface of the circuit layer located on the second copper area. The second copper area and the strain layer form an overlapping structure with the circuit layer.

4. The pressure sensing circuit board of claim 3, wherein, The pressure sensing circuit board further comprises three resistors with fixed resistance values. The three resistors form a Wheatstone bridge with the strain layer.

5. The pressure sensing circuit board of claim 1, wherein, The pressure sensing circuit board further comprises an insulating layer covering the surface of the circuit layer located on the first copper area.

6. The pressure sensing circuit board of claim 1, wherein, The method comprises the following steps:

7. A method of manufacturing a pressure sensing circuit board, characterized by: providing a copper-clad substrate comprising a medium layer and a copper layer on a surface of the medium layer; performing local copper reduction treatment on the copper layer to form a second copper area and a first copper area; removing part of the copper layer located on the second copper area to form a non-copper area, so that part of the medium layer is exposed. Circuit layer is formed by performing circuit fabrication on the copper layer. The remaining copper layer located on the second copper area is subjected to grid processing to form a grid-shaped circuit layer; forming a strain layer on the surface of the medium layer in the non-copper area; and forming a protective layer on the surface of the circuit layer in the second copper area. The protective layer also covers the strain layer, thereby forming the pressure sensing circuit board. In the stacking direction of the copper layer and the medium layer, the thickness of the strain layer is greater than the thickness of the circuit layer located on the second copper area.

8. The method of claim 7, wherein the pressure sensing circuit board is manufactured by a process comprising: In the step of forming the strain layer, the strain layer also covers the surface of the circuit layer adjacent to the second copper area.

9. The method of claim 8, wherein the pressure sensing circuit board is formed by a process comprising: After the step of forming the circuit layer, the manufacturing method further comprises:

10. The method of claim 7, wherein the pressure sensing circuit board is manufactured by a process comprising: forming an insulating layer on the surface of the circuit layer located on the first copper area. ​

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