A flexible circuit board double-layer packaging process and a double-layer packaging flexible circuit board
By using a double-layer encapsulation process for flexible circuit boards, a preliminary encapsulation layer is formed by using damming adhesive and leveling adhesive, and then injection molding is used to form an elastic encapsulation structure. This solves the problem that flexible circuit board encapsulation methods are prone to damage to flexibility, and improves mechanical strength and bending life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INST OF FLEXIBLE ELECTRONICS TECH OF THU ZHEJIANG
- Filing Date
- 2026-07-01
- Publication Date
- 2026-07-31
AI Technical Summary
Existing flexible circuit board packaging methods are prone to compromising product flexibility, resulting in reliability issues such as gold wire fatigue fracture and stress accumulation.
A dual-layer encapsulation process is adopted, including a damming step and an adhesive dispensing step to form an initial elastic encapsulation layer. Subsequently, an integral encapsulated elastic structure is formed through injection molding. Flexible colloids with different static viscosities are used to ensure flexibility and mechanical strength.
This improves the mechanical strength and bending life of the flexible circuit board while maintaining overall flexibility, ensuring a stable connection and reliability between the chip and the substrate.
Smart Images
Figure CN122497004A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of chip packaging technology, and in particular to a flexible circuit board double-layer packaging process and a double-layer packaged flexible circuit board. Background Technology
[0002] With the rapid development of wearable devices, electronic skin, implantable medical devices, and flexible sensors, COB (Chip-on-Board) modules for flexible microsystems are widely used due to their mature technology, controllable cost, and high interconnect density. This approach directly mounts bare chips onto a flexible substrate (such as polyimide PI) and achieves electrical connections through gold wire ball bonding, offering advantages such as simple structure, low cost, and mature technology. However, this technical solution faces reliability issues such as gold wire fatigue fracture and stress accumulation.
[0003] Currently, flexible circuit board packaging solutions mainly involve setting closed-loop grooves around the COB chip, with multiple arc-shaped connection holes between the closed-loop grooves and the COB chip. The surface of the COB chip and the multiple arc-shaped connection holes are filled with encapsulation material, and the closed-loop grooves are filled with a rigid adhesive material that bonds to the encapsulation material. While this solution further connects the flexible encapsulation material around the flexible encapsulation material to prevent the flexible circuit board from easily falling off during bending, the use of rigid adhesive does have a certain damaging effect on the product's flexibility. Summary of the Invention
[0004] This disclosure provides a flexible circuit board dual-layer packaging process and a dual-layer packaged flexible circuit board, in order to solve the problem that the flexible circuit board packaging method in the related technology is easily damaged and affects the flexibility of the product.
[0005] The flexible circuit board dual-layer packaging process provided in this disclosure includes the following steps: The mounting step involves mounting the flexible chip onto the flexible substrate and electrically connecting it. In the damming step, a first flexible colloid with a static viscosity of 30,000 CPS to 50,000 CPS is used to dam and encapsulate the outer periphery of the flexible chip, and the first flexible colloid is cured to form a damming colloid that protrudes from one side of the flexible substrate and surrounds the outer periphery of the flexible chip. In the dispensing step, a second flexible colloid with a static viscosity ≤5000CPS is used to dispense and encapsulate the annular area enclosed by the damming colloid. In the leveling and curing step, the second flexible colloid, after being applied, is allowed to stand to level and fill the annular area enclosed by the damming colloid, and then the second flexible colloid is heated and cured to form a leveling colloid. In the injection molding encapsulation step, a third flexible colloid is used to simultaneously encapsulate the flexible substrate, the damming colloid, and the leveling colloid to form the injection molded colloid.
[0006] In one possible implementation, during the damming step: The first flexible colloid is cured to form a dam colloid with a height of 500μm~700μm.
[0007] In one possible implementation, during the leveling and curing step: The encapsulation thickness of the second flexible colloid does not exceed the protrusion height of the dam colloid.
[0008] In one possible implementation, during the mounting step: The flexible chip is attached to the flexible substrate using a chip bonding film, anisotropic conductive adhesive, or flexible conductive adhesive, and then electrically connected to the flexible substrate by forming bonding wires using a wire bonding process.
[0009] In addition, the double-layer packaged flexible circuit board provided in this disclosure embodiment can be prepared by the above-mentioned double-layer packaged process of flexible circuit board, which includes a flexible substrate, a flexible chip, a damming colloid, a leveling colloid, and an injection molding colloid; The flexible chip is disposed on the first side of the flexible substrate and is electrically connected to the flexible substrate. The dammed colloidal protrusion is disposed on the first side of the flexible substrate and surrounds the outer periphery of the flexible chip; The leveling colloid fills the annular area enclosed by the damming colloid, and the flexible chip is coated and encapsulated accordingly. The injection-molded colloid is wrapped around the outer periphery of the flexible substrate, and together the flexible substrate, the damming colloid, and the leveling colloid are encapsulated. The damming colloid, the leveling colloid, and the injection molding colloid are all elastic colloids.
[0010] In one embodiment, the damming colloid is cured from a damming adhesive with a static viscosity of 30,000 CPS to 50,000 CPS, and the protrusion height of the damming colloid on the first side of the flexible substrate is 500 μm to 700 μm.
[0011] In one embodiment, the coating height of the leveling colloid does not exceed the protrusion height of the damming colloid; The leveling colloid is formed by leveling and curing a leveling adhesive with a static viscosity of ≤5000 CPS.
[0012] In one embodiment, the leveling colloid has an elastic modulus of 0.5 MPa to 5 MPa and a hardness of 10 Shore A to 30 Shore A.
[0013] In one embodiment, the elastic modulus of the injection-molded colloid is 5 MPa to 20 MPa, and the hardness is 30 Shore A to 60 Shore A.
[0014] In one embodiment, the double-layer encapsulated flexible circuit board further includes a bonding wire located in the annular region enclosed by the dammed colloid; One end of the bonding wire is connected to the flexible substrate, and the other end is connected to the flexible chip, and is encapsulated by the leveling colloid.
[0015] The technical solution provided in this disclosure has the following advantages compared with related technologies: The flexible circuit board dual-layer encapsulation process provided in this disclosure can be used to prepare dual-layer encapsulated flexible circuit boards. It achieves efficient and reliable protection of the flexible chip through a two-layer structure of "dispensing encapsulation + injection molding." The first layer, "dispensing encapsulation," employs a two-step dispensing process of "damming adhesive + coating adhesive" to ensure that a preliminary elastic encapsulation layer of a certain thickness is formed between the flexible chip and the flexible substrate. The second layer, "injection molding," uses silicone for injection molding to form an overall encapsulated elastic structure, further improving the overall mechanical strength and bending life of the dual-layer encapsulated flexible circuit board. Furthermore, the aforementioned damming adhesive, leveling adhesive, and injection molding adhesive are all elastic adhesives and will not damage or affect the overall flexibility of the dual-layer encapsulated flexible circuit board. This flexible circuit board dual-layer encapsulation process is simple, convenient to operate, and can efficiently and stably prepare and produce dual-layer encapsulated flexible circuit boards.
[0016] Furthermore, the dual-layer encapsulated flexible circuit board provided in this embodiment achieves efficient and reliable protection for the flexible chip through a two-layer structure of "dispensing encapsulation + injection molding". The first layer of "dispensing encapsulation" adopts a two-step dispensing process of "damming adhesive + coating adhesive" to ensure that a preliminary elastic encapsulation layer of a certain thickness can be formed between the flexible chip and the flexible substrate. The second layer of "injection molding" uses silicone for injection molding to form an overall encapsulated elastic encapsulation structure, which further improves the overall mechanical strength and bending life of the dual-layer encapsulated flexible circuit board. Moreover, the damming adhesive, leveling adhesive and injection molding adhesive mentioned above are all elastic adhesives and will not damage or affect the overall flexibility of the dual-layer encapsulated flexible circuit board.
[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description
[0018] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.
[0019] Figure 1 The diagram illustrates the steps of a flexible circuit board dual-layer packaging process provided in an embodiment of this disclosure. Figure 2 A schematic diagram of a double-layer packaged flexible circuit board provided in an embodiment of this disclosure is shown.
[0020] The labels in the diagram are as follows: 1. Flexible substrate; 2. Flexible chip; 3. Damping colloid; 4. Leveling colloid; 5. Injection molding colloid; 6. Bonding wire. Detailed Implementation
[0021] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.
[0022] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.
[0023] Combination Figure 1 As shown, this disclosure provides a flexible circuit board dual-layer packaging process, which includes the following steps: Mounting step S1—Mount the flexible chip and electrically connect it to the flexible substrate; Damping step S2—Use a first flexible colloid with a static viscosity of 30000CPS~50000CPS to dam and encapsulate the outer periphery of the flexible chip, and let the first flexible colloid solidify to form a dam colloid 3 that protrudes on one side of the flexible substrate 1 and surrounds the outer periphery of the flexible chip 2. Dispensing step S3—Use a second flexible colloid with a static viscosity ≤5000CPS to dispense and encapsulate the annular area enclosed by the damming colloid 3; Leveling and curing step S4—Let stand to allow the second flexible colloid after dispensing to level and fill the annular area surrounded by the damming colloid, and then heat and cure the second flexible colloid to form leveling colloid 4. Injection molding encapsulation step S5—The flexible substrate 1, the damming colloid 3, and the leveling colloid 4 are simultaneously encapsulated using a third flexible colloid to form an injection molded colloid.
[0024] Specifically, in combination Figure 1 In further detail, the flexible circuit board double-layer encapsulation process can be used to prepare the above-mentioned double-layer encapsulated flexible circuit board, and the first flexible adhesive in the damming step S2 can be, but is not limited to, the above-mentioned damming adhesive, the second flexible adhesive in the damming step S2 can be, but is not limited to, the above-mentioned leveling adhesive; the third flexible adhesive in the injection molding encapsulation step S5 can be, but is not limited to, the above-mentioned silicone.
[0025] This flexible circuit board dual-layer encapsulation process achieves efficient and reliable protection for flexible chips through a two-layer structure of "dispensing encapsulation + injection molding". The first layer, "dispensing encapsulation", adopts a two-step dispensing process of "damming adhesive + coating adhesive" to ensure that a preliminary elastic encapsulation layer of a certain thickness can be formed between the flexible chip and the flexible substrate. The second layer, "injection molding", uses silicone for injection molding to form an overall encapsulated elastic structure, further improving the overall mechanical strength and bending life of the dual-layer encapsulated flexible circuit board. Moreover, the damming adhesive, leveling adhesive, and injection molding adhesive mentioned above are all elastic adhesives and will not damage or affect the overall flexibility of the dual-layer encapsulated flexible circuit board. This flexible circuit board dual-layer encapsulation process is simple and easy to operate, and can efficiently and stably produce dual-layer encapsulated flexible circuit boards.
[0026] In one possible implementation, in the damming step S2: A first flexible colloid with a static viscosity of 30,000 CPS to 50,000 CPS is used to dam and encapsulate the outer periphery of the flexible substrate, and the first flexible colloid is cured to form a dam colloid 3 with a height of 500 μm to 700 μm.
[0027] Specifically, a first flexible colloid with a static viscosity of 30,000 CPS to 50,000 CPS is used to dam and encapsulate the outer periphery of the flexible substrate. This ensures that the shape of the first flexible colloid remains stable and does not level out during the dispensing and damming process, and also ensures that the cured dam colloid 3 adheres stably to the flexible substrate 1. Furthermore, the height of the dam colloid 3 is limited to 500 μm to 700 μm. This ensures the effective dam protrusion height of the dam colloid 3 while preventing the dam colloid 3 from being too high and affecting the thickness of the double-layer encapsulated flexible circuit board.
[0028] In one possible implementation, during the leveling and curing step S4: A second flexible colloid with a static viscosity ≤5000 CPS is used to apply adhesive to the annular area enclosed by the dam colloid, and the encapsulation thickness of the second flexible colloid does not exceed the protrusion height of the dam colloid.
[0029] Specifically, a second flexible colloid with a static viscosity ≤5000 CPS is used to apply adhesive to the annular area enclosed by the damming colloid 3. This ensures that the second flexible colloid flows evenly and leveles within the annular area enclosed by the damming colloid 3. Furthermore, the encapsulation thickness of the second flexible colloid is set to not exceed the protrusion height of the damming colloid, ensuring that the leveling colloid 4 formed by the cured second flexible colloid does not extend beyond the damming colloid 3.
[0030] In one possible implementation, during the mounting step S1: The flexible chip 2 is attached to the flexible substrate 1 using a chip bonding film, anisotropic conductive adhesive, or flexible conductive adhesive, and then the flexible chip 2 is further electrically connected to the flexible substrate 1 by forming a bonding wire 6 using a wire bonding process.
[0031] Specifically, the flexible chip 2 is attached to the flexible substrate 1 using a chip bonding film, anisotropic conductive adhesive, or flexible conductive adhesive. This ensures the firmness of the flexible chip 2 on the flexible substrate 1. Furthermore, a wire bonding process is used to form a bonding wire 6 to electrically connect the flexible chip 2 to the flexible substrate 1, thus ensuring the stable and reliable power connection of the flexible chip 2.
[0032] In addition, this disclosure also provides a double-layer encapsulated flexible circuit board, which can be manufactured by the above-mentioned double-layer encapsulation process for flexible circuit boards. It includes a flexible substrate 1, a flexible chip 2, a damming colloid 3, a leveling colloid 4, and an injection molding colloid 5. The flexible chip 2 is disposed on the first side of the flexible substrate 1 and is electrically connected to the flexible substrate 1. The damming colloid 3 protrudes from the first side of the flexible substrate 1 and surrounds the outer periphery of the flexible chip 2. The leveling colloid 4 fills the annular area surrounded by the damming colloid 3 and correspondingly encapsulates the flexible chip 2. The injection molding colloid 5 is wrapped around the outer periphery of the flexible substrate 1 and encapsulates the flexible substrate 1, the damming colloid 3, and the leveling colloid 4 together. The damming colloid 3, the leveling colloid 4, and the injection molding colloid 5 are all elastic colloids.
[0033] In the specific fabrication of the dual-layer packaged flexible circuit board provided in this embodiment, a flexible circuit can first be fabricated on the flexible substrate 1 by etching. Then, passive components such as resistors, capacitors, and inductors are mounted on the corresponding positions of the flexible substrate 1 by reflow soldering using flexible surface mount technology. Next, the flexible chip 2 is thinned to the required mounting thickness (e.g., thickness not greater than 50 micrometers). The flexible chip 2 is then mounted on the corresponding positions of the flexible substrate 1 using chip bonding film (DAF), anisotropic conductive adhesive (ACF), or flexible conductive adhesive. Finally, the flexible substrate 1 and the flexible chip 2 are electrically connected by wire bonding. Next, a damming adhesive with a static viscosity of 30,000 CPS to 50,000 CPS can be used. Such a static viscosity damming adhesive can ensure that the shape does not level out during the dispensing and damming process, and can also ensure that the damming adhesive adheres stably to the flexible substrate 1, preventing it from falling off or lifting during the dispensing and damming process. After the damming adhesive is cured, it can form an elastic ring-shaped damming adhesive 3 that protrudes and surrounds one side of the flexible substrate 1 and correspondingly surrounds the outer periphery of the flexible chip 2. Then, a leveling adhesive with a static viscosity of ≤5000CPS can be applied to the annular area enclosed by the damming adhesive 3 for leveling, so that the leveling adhesive can be cured after uniformly coating the flexible chip 2 to form an elastic leveling adhesive 4. Finally, silicone can be used as the injection molding compound to encapsulate the flexible substrate 1, the damming compound 3, and the leveling compound 4 together, thereby forming an elastic injection molding compound 5, thus finally producing the double-layer encapsulated flexible circuit board.
[0034] The dual-layer encapsulated flexible circuit board provided in this embodiment achieves efficient and reliable protection for the flexible chip 2 through a two-layer structure of "dispensing encapsulation + injection molding". The first layer of "dispensing encapsulation" adopts a two-step dispensing process of "damming adhesive + coating adhesive" to ensure that a preliminary elastic encapsulation layer of a certain thickness can be formed between the flexible chip 2 and the flexible substrate 1. The second layer of "injection molding" uses silicone for injection molding to form an overall encapsulated elastic encapsulation structure, which further improves the overall mechanical strength and bending life of the dual-layer encapsulated flexible circuit board. Moreover, the damming adhesive 3, leveling adhesive 4 and injection molding adhesive 5 are all elastic adhesives and will not damage or affect the overall flexibility of the dual-layer encapsulated flexible circuit board.
[0035] In one embodiment, the damming colloid 3 is cured from a damming adhesive with a static viscosity of 30,000 CPS to 50,000 CPS, and the protrusion height of the damming colloid 3 on the first side of the flexible substrate 1 is 500 μm to 700 μm.
[0036] Specifically, in combination Figure 2 In further detail, the damming adhesive 3 is cured using a damming adhesive with a static viscosity of 30,000 CPS to 50,000 CPS. This static viscosity ensures the damming adhesive maintains its shape and prevents it from leveling out during the dispensing process, while also ensuring stable adhesion between the damming adhesive and the flexible substrate 1, preventing detachment or lifting during the dispensing process. The protrusion height of the damming adhesive 3 is set to 500 μm to 700 μm. This ensures an effective damming protrusion height while preventing the damming adhesive 3 from being too high and affecting the thickness of the double-layer encapsulated flexible circuit board.
[0037] In one embodiment, the coating height of the leveling colloid 4 does not exceed the protrusion height of the damming colloid 3; the leveling colloid 4 is formed by leveling and curing of a leveling adhesive with a static viscosity ≤5000CPS.
[0038] Specifically, in combination Figure 2 To elaborate further, the coating height of the leveling colloid 4 can be, but is not limited to, equal to the protrusion height of the damming colloid 3. Moreover, the leveling colloid 4 is formed by leveling and curing a leveling colloid with a static viscosity of ≤5000CPS. In this way, the leveling colloid with a static viscosity of ≤5000CPS can be uniformly leveled in the annular area enclosed by the damming colloid 3, ensuring that the flexible chip 2 can be uniformly coated and encapsulated.
[0039] In one embodiment, the leveling colloid 4 has an elastic modulus of 0.5 MPa to 5 MPa and a hardness of 10 Shore A to 30 Shore A.
[0040] Specifically, the elastic modulus of the leveling colloid 4 is selected as 0.5MPa~5MPa and the hardness is selected as 10Shore A~30Shore A. In this way, the laminar leveling colloid 4 formed in the inner layer can have excellent stress buffering ability and can absorb more bending stress, thereby fully exerting the function of protecting the flexible chip 2.
[0041] In one embodiment, the elastic modulus of the injection-molded colloid 5 is 5 MPa to 20 MPa, and the hardness is 30 Shore A to 60 Shore A.
[0042] Specifically, the elastic modulus of the injection-molded colloid 5 is selected as 5MPa~20MPa and the hardness is selected as 30Shore A~60Shore A. In this way, the injection-molded colloid 5 formed on the outer layer can have excellent mechanical strength and wear resistance and impact resistance, provide better structural support, and improve the tear resistance of the double-layer encapsulated flexible circuit board.
[0043] In one embodiment, the double-layer encapsulated flexible circuit board further includes a bonding wire 6 located in the annular region enclosed by the damming colloid 3; one end of the bonding wire 6 is connected to the flexible substrate 1, the other end is connected to the flexible chip 2, and is encapsulated by the leveling colloid 4.
[0044] Specifically, the bonding wire 6 can be directly fabricated using wire bonding technology. This ensures the stability of the electrical connection between the flexible substrate 1 and the flexible chip 2 through the use of multiple bonding wires 6. Furthermore, since the bonding wire 6 is located within the annular region enclosed by the damming colloid 3, when the leveling colloid 4 fills this annular region, it can also coat and encapsulate the bonding wire 6, ensuring that the bonding wire 6 also has a long bending lifespan.
[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.
[0046] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.
Claims
1. A flexible circuit board dual layer packaging process, characterized by, Includes the following steps: The mounting step involves mounting the flexible chip onto the flexible substrate and electrically connecting it. In the damming step, a first flexible colloid with a static viscosity of 30,000 CPS to 50,000 CPS is used to dam and encapsulate the outer periphery of the flexible chip, and the first flexible colloid is cured to form a damming colloid that protrudes from one side of the flexible substrate and surrounds the outer periphery of the flexible chip. In the dispensing step, a second flexible colloid with a static viscosity ≤5000CPS is used to dispense and encapsulate the annular area enclosed by the damming colloid. In the leveling and curing step, the second flexible colloid, after being applied, is allowed to stand to level and fill the annular area enclosed by the damming colloid, and then the second flexible colloid is heated and cured to form a leveling colloid. In the injection molding encapsulation step, a third flexible colloid is used to simultaneously encapsulate the flexible substrate, the damming colloid, and the leveling colloid to form the injection molded colloid.
2. The flexible circuit board dual layer packaging process of claim 1, wherein, In the aforementioned damming process: The first flexible colloid is cured to form a dam colloid with a height of 500μm~700μm.
3. The flexible circuit board dual layer packaging process of claim 1, wherein, In the leveling and curing step: The encapsulation thickness of the second flexible colloid does not exceed the protrusion height of the dam colloid.
4. The flexible circuit board dual layer packaging process of claim 1, wherein, In the mounting step: The flexible chip is attached to the flexible substrate using a chip bonding film, anisotropic conductive adhesive, or flexible conductive adhesive, and then electrically connected to the flexible substrate by forming bonding wires using a wire bonding process.
5. A double layer package flexible circuit board, which can be prepared by the double layer package process of the flexible circuit board according to any one of claims 1 to 4, characterized in that, include: Flexible substrate (1); A flexible chip (2) is disposed on the first side of the flexible substrate (1) and electrically connected to the flexible substrate (1); The dammed colloid (3) is protruded on the first side of the flexible substrate (1) and surrounds the outer periphery of the flexible chip (2); The leveling colloid (4) is filled into the annular area enclosed by the damming colloid (3), and the flexible chip (2) is coated and encapsulated accordingly. The injection molding colloid (5) is wrapped around the outer periphery of the flexible substrate (1), and the flexible substrate (1), the damming colloid (3) and the leveling colloid (4) are jointly wrapped and encapsulated. Among them, the dam-forming colloid (3), the leveling colloid (4), and the injection molding colloid (5) are all elastic colloids.
6. The double-layered package flexible circuit board of claim 5, wherein, The damming colloid (3) is cured from a damming adhesive with a static viscosity of 30000CPS~50000CPS, and the damming colloid (3) has a protrusion height of 500μm~700μm on the first side of the flexible substrate (1).
7. The double-layered package flexible circuit board of claim 6, wherein, The coating height of the leveling colloid (4) shall not exceed the protrusion height of the damming colloid (3); The leveling colloid (4) is formed by leveling and curing of a leveling colloid with a static viscosity of ≤5000CPS.
8. The double-layered package flexible circuit board of claim 5, wherein, The leveling colloid (4) has an elastic modulus of 0.5 MPa to 5 MPa and a hardness of 10 Shore A to 30 Shore A.
9. The double-layered package flexible circuit board of claim 5, wherein, The elastic modulus of the injection-molded colloid (5) is 5MPa~20MPa and the hardness is 30Shore A~60Shore A.
10. The double-layered package flexible circuit board of claim 5, wherein, The double-layer encapsulated flexible circuit board also includes a bonding wire (6) located in the annular region enclosed by the dam colloid (3). One end of the bonding wire (6) is connected to the flexible substrate (1), and the other end is connected to the flexible chip (2), and is encapsulated by the leveling colloid (4).