A method and structure for encapsulating a rigid-flex substrate assembly

Abstract

The application discloses a kind of rigid-flexible substrate assembly's stack potting structure and manufacturing method, belong to electronic packaging technical field, by using multiple interlayer backing plate, with the rigid substrate that is assembled component is laminated and assembled combination, and in the bottom of stack pasteboard, form small volume semi-sealed cavity for potting, can be carried out potting without mould, simultaneously, since the potting cavity formed can be closely final product outer contour design, so that the area that needs to be injected epoxy glue can be as small as possible, can reduce the consumption of high value special potting glue, also suitable for the potting product of higher small size requirement to final circuit product, in addition, the method can also reduce potting glue usage by reducing potting space, so as to reduce the reaction heat when glue solidifies, reach to reduce potting glue solidification stress, further reduce the negative mechanical influence to the internal device that is potting.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic packaging, and in particular relates to a method and structure for manufacturing a stacked potting structure of a rigid-flex substrate assembly. Background Art

[0002] Rigid-flex substrates, which combine rigid and flexible substrates, offer advantages such as high inter-board interconnect density and foldability. Components can be assembled on rigid substrates using the same soldering or bonding methods as conventional organic substrates. The bendable and foldable nature of flexible substrates allows multiple rigid substrates to be electrically interconnected and folded into a compact space. Therefore, by folding a rigid-flex substrate and then encapsulating it with epoxy, circuit size can be significantly reduced, while achieving higher inter-board interconnect density and reducing the size and weight of the circuit product.

[0003] In some specialized process environments, potting products require a very high thermal expansion coefficient match between the mold and the internal components. If tensile stress occurs during the curing process due to a mismatch in the material properties of the potting cavity and the workpiece being potted, it will adversely affect the potted component. This makes it difficult to use high-hardness metal molds that are durable and easy to demold, while molds made of flexible materials like silicone have low dimensional accuracy. If a product uses high-value potting compounds, the potting cavity must be as small as possible to reduce material costs. Summary of the Invention

[0004] The present invention provides a method and structure for manufacturing a stacked potting structure of a rigid-flex substrate assembly, which solves the problem that tensile stress occurs during the curing process of the potting glue due to the deviation in material properties between the potting cavity and the potted workpiece, which will have an adverse effect on the effect of the potted components.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for manufacturing a stacked potting structure of a rigid-flex substrate assembly, comprising:

[0007] At least one flexible substrate is used to connect two rigid substrates, and the two rigid substrates are bent so as to be parallel, wherein one of the rigid substrates has a solder pad or an external lead and is arranged at the bottom;

[0008] A second pad is installed on one side of the two rigid substrates close to the flexible substrate, a first pad is installed on top of the two rigid substrates, and a second pad is installed on the side of the first pad. The second pad and the first pad can form a rectangular pad with a hollow U-shaped backing;

[0009] Install the baffle on the top hollow rectangular pad;

[0010] Place the rigid substrate with pads or external leads upwards, and pour epoxy potting glue from the hollow area on one side of the flexible substrate until the liquid surface is flush with the edge of the substrate;

[0011] After the potting compound is cured, remove the bottom baffle and cut off the excess potting compound and backing plate.

[0012] Preferably, the first pad and the second pad are bonded together, and the second pad is bonded to the rigid substrate.

[0013] Preferably, a docking port is provided on one side of the rigid substrate connected to the second pad, and the docking port on the rigid substrate is adapted to the docking port on the second pad.

[0014] Preferably, the rigid-flex substrate assembly is stacked by bending the flexible substrate 180 degrees.

[0015] Preferably, when installing the pads between the rigid substrates, adhesive is used to pre-set a pad mounting area on the rigid substrate, and the assembled hollow rectangular pads are bonded to the pad mounting area;

[0016] Preferably, the area of ​​the hollow rectangular pad formed by the first pad and the second pad is equal to the area after the rigid substrate and the second pad are bonded together.

[0017] Preferably, the baffle is made of the same material as the rigid substrate.

[0018] Preferably, the length of the hollow rectangular pad formed by the first pad and the second pad is greater than the length of the final potted product.

[0019] Preferably, the distance that the length of the hollow rectangular pad formed by the first pad and the second pad is greater than the length of the final potting product is less than 100 μm.

[0020] A stacking potting structure of a rigid-flex substrate assembly is manufactured based on a method for manufacturing a stacking potting structure of a rigid-flex substrate assembly.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a method for manufacturing a stacked potting structure of a rigid-flexible substrate assembly, which utilizes multiple interlayer pads to be assembled with a rigid substrate with assembled components, and a bottom baffle is mounted to form a small-volume semi-sealed cavity for potting, which can achieve potting without a mold. At the same time, since the formed potting cavity can be designed to fit the outer contour of the final product, the area requiring epoxy glue to be poured can be made as small as possible, which can reduce the consumption of high-value special potting glue. Therefore, it is also suitable for products with high requirements for the small size of the final circuit product. In addition, this method can also reduce the amount of potting glue used by reducing the potting space, thereby reducing the reaction heat when the glue is cured, thereby reducing the curing stress of the potting glue, and further reducing the negative mechanical effects on the internal devices being potted.

[0022] Furthermore, the interlayer pad material is the same as the rigid substrate material, so the potting cavity material does not have the problem of mismatching with the material properties of the potting structure, which is suitable for products that are sensitive to stress changes in the potting cavity during the potting and curing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of assembling components on a rigid substrate.

[0024] Figure 2 Schematic diagram of a bent flexible substrate.

[0025] Figure 3 Schematic diagram of mounting the pad ① next to the bottom rigid plate.

[0026] Figure 4 Schematic diagram of mounting pad ② between the bottom rigid substrate and the upper rigid substrate.

[0027] Figure 5 This is a schematic diagram of mounting pad ③ next to pad ②.

[0028] Figure 6 This is a schematic diagram of mounting a pad ④ next to the upper rigid substrate.

[0029] Figure 7 Schematic diagram of mounting pad ⑤ on top of the upper rigid substrate.

[0030] Figure 8 This is a schematic diagram of mounting pad ⑥ next to pad ⑤.

[0031] Figure 9 Schematic diagram of mounting a removable top baffle on a stack.

[0032] Figure 10 Schematic diagram of epoxy potting of the stack.

[0033] Figure 11 Schematic diagram of epoxy curing.

[0034] Figure 12 Figure 1 is a schematic view of a bottom stopper.

[0035] Figure 13 Figure 2 is a schematic view of cutting off the pad plate and potting glue outside the product functional area.

[0036] Figure 14 Figure 3 is a schematic view of completing the rest of the product processing.

[0037] Figure 15 Figure 4 is a top view of a rigid-flex substrate.

[0038] Figure 16 Figure 5 is a top view of an interlayer pad plate.

[0039] In the figure: 1-rigid substrate, 2-flexible substrate, 3-first pad plate, 4-butting opening, 5-mounting area, 6-second pad plate. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0042] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0043] In the description of the embodiments of the present application, it should be noted that if the orientation or position relationship indicated by the terms "upper", "lower", "horizontal", "inner" and the like is based on the orientation or position relationship shown in the drawings, or is the orientation or position relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0044] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. As "horizontal" only means that it is more horizontal than "vertical", it does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0045] In the description of the embodiments of the present application, it should also be noted that, unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings.

[0047] An embodiment of the present application provides a kind of rigid-flex substrate assembly stack potting structure manufacturing method, comprising:

[0048] At least one flexible substrate 2 is used to connect two rigid substrates 1, and is bent to make two rigid substrates 1 parallel, wherein one rigid substrate 1 is provided with a solder pad or an external lead, and is arranged at the bottom;

[0049] Second backing plate 6 is installed on the side of the two rigid substrates 1, first backing plate 3 is installed on the top of the two rigid substrates 1, and second backing plate 6 is installed on the side of the first backing plate 3, and the second backing plate 6 and the first backing plate 3 form a hollow rectangular backing plate;

[0050] The baffle is installed on the top of the hollow rectangular backing plate;

[0051] The side of the rigid substrate 1 with the solder pad or the external lead is upward, and the epoxy potting adhesive is poured from the side of the flexible substrate 2 hollow area until the liquid level is flush with the edge of the substrate;

[0052] After the completion of potting adhesive curing, the bottom baffle is removed, and the excess potting adhesive and backing plate are cut off.

[0053] The first backing plate 3 and the second backing plate 6 are bonded together, and the second backing plate 6 is bonded with the rigid substrate 1.

[0054] The side of the rigid substrate 1 connected with the second backing plate 6 is provided with a mating interface, and the mating interface on the rigid substrate 1 is matched with the mating interface of the second backing plate 6.

[0055] Specifically:

[0056] Stack and assemble the rigid substrate 1 part and the concave-shaped interlayer pad made of the same material;

[0057] Both the rigid substrate 1 and the interlayer pad are provided with docking interfaces;

[0058] Place two interlayer pads between the rigid substrates 1 at the corresponding positions of the docking interfaces, and bond them with a low-stress adhesive at the docking interface and the mounting area of ​​the substrates;

[0059] Place a concave interlayer pad on the edge of each rigid substrate 1, with its opening facing the flexible substrate 2, and use adhesive to bond the pad to the rigid substrate 1 at the interface and mounting area;

[0060] Bend multiple rigid-flex substrates 180° through the flexible substrate 2 to achieve stacking assembly;

[0061] A removable bottom baffle made of the same material as the rigid substrate 1 is mounted on the bottom of the stack;

[0062] Through the above stacking assembly, a potting cavity consisting of a rigid-flex board, an interlayer pad, and a baffle made of the same material is formed, enclosing the substrate to be packaged and the components therein;

[0063] The thickness of the interlayer pad is designed according to the stacking spacing of the rigid substrate 1;

[0064] The potting cavity can be designed to be close to the outer edge size of the final potted product, such as a margin of less than 100μm;

[0065] After potting and curing are completed and the excess parts are removed, the remaining assembly procedures are completed to form a fully functional circuit module.

[0066] Another embodiment of the present invention provides a stacking potting structure design method for a rigid-flex substrate assembly, comprising a rigid-flex substrate, a concave-shaped interlayer pad made of the same material as the rigid substrate 1, and a removable bottom baffle;

[0067] Both the rigid substrate 1 and the interlayer pad are provided with docking interfaces;

[0068] The specific size and thickness of each interlayer pad are adapted to the final product, and the thickness of the interlayer pad is equal to the stacking spacing height designed for the rigid substrate 1;

[0069] The rigid substrate 1 after component assembly is bent 180° through the flexible substrate 2 to achieve stacking;

[0070] During the stacking assembly process, two concave-shaped interlayer pads are placed relative to each other at the interface above or below the rigid substrate 1 to form a hollow U-shaped cavity, and the interface joints of the two interlayer pads are bonded with a low-stress adhesive.

[0071] During the stacking assembly process, a low-stress adhesive is used to bond the assembled interlayer pads to the pre-set "pad mounting area" on the rigid substrate 1;

[0072] During the stacking assembly process, on the same horizontal plane of the rigid substrate 1, a "concave" shaped pad is used to splice with the docking interface of the rigid substrate 1 to form a hollow "U" shaped cavity together with the rigid substrate 1, and the docking interface is bonded by adhesive;

[0073] The inner and outer contours of each layer of the "U"-shaped cavity formed by the pads and the pads and the rigid substrate 1 are consistent in size;

[0074] In addition to the interlayer pad at the bottom of the stack, a detachable bottom baffle made of the same material as the rigid substrate 1 needs to be bonded with a low-stress adhesive;

[0075] The interlayer pad, the rigid substrate 1 and the bottom baffle are bonded layer by layer in a stacked state, and the staggered stacking forms a "U"-shaped cavity, which is the potting cavity;

[0076] The size of the potting cavity formed after stacking can be designed to be close to the outer edge size of the final potted product;

[0077] During the formal potting, the potting compound is injected from the hollow area on the side of the substrate where the product needs to be exposed, that is, the substrate with external leads or pads, until the liquid level rises to the same level as the edge of the substrate and submerges the flexible substrate 2 connected to it;

[0078] After the epoxy glue is cured, the area outside the functional area of ​​the product is cut off and the remaining circuit assembly work is completed to obtain a complete circuit product.

[0079] The present invention proposes a stacking potting structure design for a rigid-flex substrate assembly, such as Figures 1 to 15 As shown:

[0080] It includes two rigid substrates 1 connected by at least one flexible substrate 2 that can be folded 180 degrees, one of which is a substrate with external leads / pads, such as Figure 1 As shown;

[0081] The surfaces of the two rigid substrates 1 are provided with non-functional mounting areas;

[0082] The area surrounding the non-functional mounting area is slightly larger than the final product size;

[0083] The interlayer pad is made of the same material as the rigid substrate 1;

[0084] The interlayer pad is in the shape of a "concave" character, and the area of ​​the central opening is equal to the area within the surrounding range of the mounting area on the rigid substrate 1;

[0085] The interlayer pads are divided into multiple pieces, and the thickness is designed according to the spacing height requirements of the rigid substrate 1 after lamination in the product;

[0086] After the flexible substrate 2 is bent 180°, the rigid substrate 1 is vertically aligned, as shown in FIG. Figure 2 As shown;

[0087] The interlayer pads are glued on the surface of the rigid substrate 1 with low stress adhesive, and the "concave" shaped interlayer pads placed opposite to the butt opening are glued layer by layer with liquid glue to form a semi-enclosed potting cavity. Figures 3 to 9 As shown;

[0088] After the stacked structure is assembled, a removable bottom baffle made of the same material as the rigid substrate 1 is mounted on the outermost interlayer pad as the bottom of the potting cavity. Figure 10 As shown;

[0089] When potting, place the side of the circuit board with external leads or pads upwards, and pour epoxy potting glue from the hollow area of ​​the flexible board until the liquid level is flush with the edge of the substrate. Figure 11 As shown;

[0090] After the potting glue is cured, remove the bottom baffle. Figure 12 、 13 As shown;

[0091] Cut and remove the potting compound and backing plate outside the product area, such as Figure 14 As shown;

[0092] Complete the rest of the product assembly process, such as Figure 15 and 16 shown.

[0093] The present invention is designed by designing a stacked potting structure of a rigid-flexible substrate assembly. The present invention is based on the use of a rigid substrate 1 and an interlayer pad and a bottom baffle coating of the same material to form a potting cavity. Under the premise of achieving potting cavity material performance matching, the volume of the potting cavity can be reduced as much as possible, thereby helping to prevent stress differences from being generated during potting and curing. It can save costs when using high-value potting glue, and can reduce the impact of curing stress on the product by reducing the amount of potting glue injected. This method has strong design flexibility and a simple assembly method. It can achieve potting without a mold and has high application value for special electronic products that are packaged with high-value potting glue and are sensitive to stress during the potting and curing process.

[0094] Although the embodiments of the present application have been described above with reference to the accompanying drawings, the present application is not limited to the above-described specific embodiments and areas of application, and the above-described specific embodiments are merely illustrative and instructive, but are not restrictive. Those skilled in the art can make various modifications under the teachings of the specification, and such modifications are also within the scope of the present application protected by the claims.

Claims

1. A method for manufacturing a stacked potting structure of a rigid-flex substrate assembly, characterized in that: Comprising: Using at least one flexible substrate (2) to connect two rigid substrates (1), and bending to make the two rigid substrates (1) parallel, with one of the rigid substrates (1) having pads or external leads and being arranged at the bottom; Installing a second backing plate (6) on the side of the two rigid substrates (1) close to the flexible substrate (2), installing a first backing plate (3) on the top of the two rigid substrates (1), and installing a second backing plate (6) on the side of the first backing plate (3), and the second backing plate (6) and the first backing plate (3) can form a rectangular backing plate with a hollowed-out square shape; Installing a baffle on the hollowed-out rectangular backing plate at the top; Turning the side of the rigid substrate (1) with pads or external leads upwards, and pouring epoxy encapsulation adhesive from the hollowed-out area on the side of the flexible substrate (2) until the liquid level is flush with the edge of the substrate; After the encapsulation adhesive is cured, removing the bottom baffle, and cutting off the excess encapsulation adhesive and backing plates.

2. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: The first backing plate (3) and the second backing plate (6) are bonded together, and the second backing plate (6) is bonded to the rigid substrate (1).

3. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: On the side of the rigid substrate (1) connected to the second backing plate (6), an interface is provided, and the interface on the rigid substrate (1) is adapted to the interface of the second backing plate (6).

4. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, wherein: The rigid-flexible substrate assembly is stacked and placed through a 180° bending of the flexible substrate (2).

5. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: When installing the backing plates between the rigid substrates (1), a backing plate mounting area (5) is preset on the rigid substrate (1) using an adhesive, and the assembled hollowed-out rectangular backing plate is bonded on the backing plate mounting area (5).

6. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, wherein: The area of the hollowed-out rectangular backing plate formed by the first backing plate (3) and the second backing plate (6) is equal to the area after the rigid substrate (1) and the second backing plate (6) are bonded together.

7. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: The material of the baffle is the same as that of the rigid substrate (1).

8. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: The length of the hollowed-out rectangular backing plate formed by the first backing plate (3) and the second backing plate (6) is greater than the length of the final encapsulated product.

9. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 8, characterized in that: The distance by which the length of the hollowed-out rectangular backing plate formed by the first backing plate (3) and the second backing plate (6) is greater than the length of the final encapsulated product is less than 100 μm.

10. A stacking potting structure of a rigid-flex substrate assembly, characterized in that: Manufactured based on the manufacturing method of the stacked encapsulation structure of the rigid-flexible substrate assembly according to any one of claims 1-9.

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