Manufacturing method and structure of stack potting structure of rigid-flex substrate assembly

Abstract

The invention discloses a stacking and potting structure of a rigid-flex substrate assembly and a manufacturing method, and belongs to the technical field of electronic packaging, a plurality of interlayer base plates and a rigid substrate assembled with components are laminated, assembled and combined, and a baffle plate is attached to the bottom of a stacking body to form a small-size semi-sealed cavity for potting, so that the small-size semi-sealed cavity is formed; according to the utility model, the encapsulation can be carried out under the condition of no mold, and meanwhile, the formed encapsulation cavity can be designed to be clung to the outer contour of the final product, so that the area in which the epoxy glue needs to be injected is as small as possible, the consumption of high-value special encapsulation glue can be reduced, and the encapsulation method is also suitable for encapsulation products with higher small size requirements on the final circuit product; in addition, according to the method, the use amount of the pouring sealant can be reduced by reducing the pouring space, so that the reaction heat during glue curing is reduced, the curing stress of the pouring sealant is reduced, and the negative mechanical influence on the encapsulated internal device is further reduced.

Description

Technical Field

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

[0002] The rigid-flexible substrate, which is a combination of a rigid substrate and a flexible substrate, has advantages such as high interconnection density between boards and foldability. Components can be assembled on a rigid substrate by welding or bonding in the same way as conventional organic substrates. The bendable and foldable characteristics of the flexible substrate allow multiple rigid substrates to be electrically interconnected and placed in a small space by folding. Therefore, by folding the rigid-flexible substrate and then using epoxy packaging, the circuit size can be greatly reduced, while achieving a higher density of interconnection between boards and reducing the size and weight of the circuit product.

[0003] In some special process use environments, potting products have very high requirements for the matching of the thermal expansion coefficients of the potting mold and the internal components. If tensile stress occurs during the curing process of the potting glue due to the deviation of the material properties of the potting cavity and the potted workpiece, it will have an adverse effect on the effect of the potted components, which is not conducive to the use of high-hardness metal molds that are not easy to damage and easy to demold, and the dimensional accuracy of flexible material molds such as silicone is low. If the product uses high-value potting glue, the potting cavity needs to 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] Use at least one flexible substrate to connect two rigid substrates, and bend them to make the two rigid substrates parallel, one of the rigid substrates has a 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 the top of the two rigid substrates, and a second pad is installed on the side of the first pad, wherein the second pad and the first pad can form a rectangular pad with a hollow U-shaped hollow.

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

[0010] Place the rigid substrate with pads or external leads facing upward, 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 matched with 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 pad between the rigid substrates, an adhesive is used to pre-set a pad mounting area on the rigid substrate, and the assembled hollow rectangular pad is 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.

[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 potted 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 a plurality of interlayer pads to be stacked and assembled with a rigid substrate on which components are assembled, and a bottom baffle is mounted to form a small-volume semi-sealed cavity for potting, and potting can be achieved 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 that needs to be poured with epoxy glue can be 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 potting glue curing stress and further reducing the negative mechanical effects on the internal devices being potted.

[0022] Furthermore, the material of the interlayer pad is the same as that of the rigid substrate, so the material of the potting cavity does not have the problem of mismatching 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 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 This is a schematic diagram of mounting a pad next to the bottom rigid plate①.

[0026] Figure 4 The diagram is a schematic diagram of mounting a pad between a bottom rigid substrate and an 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 This is a schematic diagram of mounting a 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] Fig. 9 A schematic diagram of mounting a removable top baffle on a stack.

[0032] Fig.10 Schematic diagram of epoxy potting for stacking body.

[0033] Fig.11 Schematic diagram of epoxy curing.

[0034] Fig.12 Schematic diagram for removing the bottom baffle.

[0035] Fig.13 Schematic diagram of cutting and removing the pad and potting glue outside the functional area of ​​the product.

[0036] Fig.14 To complete the rest of the product processing diagram.

[0037] Fig.15 Top view of the rigid-flex substrate.

[0038] Fig.16 This is a top view of the interlayer pad.

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

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the 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 tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0047] An embodiment of the present invention provides a method for manufacturing a stacked potting structure of a rigid-flex substrate assembly, comprising:

[0048] At least one flexible substrate 2 is used to connect two rigid substrates 1, and the two rigid substrates 1 are bent so as to be parallel, wherein one of the rigid substrates 1 has a pad or an external lead and is arranged at the bottom;

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

[0050] Install the baffle plate on the top hollow rectangular pad;

[0051] Place the rigid substrate 1 with pads or external leads facing upward, and pour epoxy potting glue from the hollow area on one side of the flexible substrate 2 until the liquid level is flush with the edge of the substrate;

[0052] After the potting compound is cured, remove the bottom baffle and cut off the excess potting compound and backing plate.

[0053] The first pad 3 and the second pad 6 are bonded together, and the second pad 6 and the rigid substrate 1 are bonded together.

[0054] A docking port is provided on one side of the rigid substrate 1 connected to the second pad 6 , and the docking port on the rigid substrate 1 is matched with the docking port on the second pad 6 .

[0055] Specific:

[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] Between the rigid substrates 1, two interlayer pads are placed at corresponding positions of the butt joints, and low-stress adhesive is used to bond the butt joints and the mounting areas of the substrates;

[0059] A "concave"-shaped interlayer pad is placed at the edge of each rigid substrate 1, with its opening facing the flexible substrate 2, and an adhesive is used to bond the pad and the rigid substrate 1 at the interface and mounting area;

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

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

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

[0063] The thickness of the interlayer pad is designed according to the stacking interval 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 <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-flexible substrate assembly, including a rigid-flexible 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 "pad mounting area" pre-set 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 spliced ​​with the butt joint of the rigid substrate 1 to form a hollow "U" shaped cavity together with the rigid substrate 1, and the butt joint is bonded by an 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 removable 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 "U"-shaped cavity formed by staggered stacking 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] In the formal potting, the potting glue is injected from the hollow area on one 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 thereto;

[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, a complete circuit product can be obtained.

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

[0080] The invention comprises two rigid substrates 1 connected by at least one flexible substrate 2 which can be folded 180 degrees, one of which is a substrate containing 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 formed by using 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 opening in the middle is equal to the area within the surrounding range of the mounting area on the rigid substrate 1;

[0085] The interlayer pad is divided into multiple pieces, and the thickness is designed according to the spacing height requirement 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, such as Figure 2 As shown;

[0087] The interlayer pad is glued on the surface of the rigid substrate 1 with a 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, such as Figure 3 to Figure 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 outside the outermost interlayer pad as the bottom of the potting cavity. Fig.10 As shown;

[0089] When potting, place the side of the circuit board with external leads or pads upward, and pour epoxy potting glue from the "concave" hollow area on one side of the flex board until the liquid level is flush with the edge of the substrate. Fig.11 As shown;

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

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

[0092] Complete the rest of the product assembly process, such as Fig.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 combination of the same material to form a potting cavity. On the premise of achieving potting cavity material performance matching, the volume of the potting cavity can be reduced as much as possible, which is beneficial to prevent stress differences from being generated during the potting and curing process. 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 injection. The method has strong design flexibility and simple assembly method. Potting can be achieved without a mold. It 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 invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields, and the above-mentioned specific embodiments are only illustrative and instructive, rather than restrictive. Under the guidance of the specification, a person skilled in the art can also make many forms without departing from the scope of protection of the claims of the present invention, all of which belong to the scope of protection of the present invention.

Claims

1. A method for manufacturing a stacked potting structure of a rigid-flex substrate assembly, characterized in that: include: At least one flexible substrate (2) is used to connect two rigid substrates (1), and is bent so that the two rigid substrates (1) are parallel, wherein one of the rigid substrates (1) has a solder pad or an external lead and is arranged at the bottom; A second pad (6) is installed on one side of the two rigid substrates (1) close to the flexible substrate (2), a first pad (3) is installed on the top of the two rigid substrates (1), and a second pad (6) is installed on the side of the first pad (3), wherein the second pad (6) and the first pad (3) can form a rectangular pad with a hollow U-shaped hollow. Install the baffle plate on the top hollow rectangular pad; Place the rigid substrate (1) with the pad or external lead facing upward, and pour epoxy potting glue from the hollow area on one side of the flexible substrate (2) until the liquid surface is flush with the edge of the substrate; After the potting compound is cured, remove the bottom baffle and cut off the excess potting compound and backing plate.

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

3. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: A docking port is provided on one side of the rigid substrate (1) connected to the second pad (6); the docking port on the rigid substrate (1) is adapted to the docking port on the second pad (6).

4. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: The rigid-flex substrate assembly is stacked by bending the flexible substrate (2) by 180 degrees.

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 pads between the rigid substrates (1), an adhesive is used to pre-set a pad mounting area (5) on the rigid substrate (1), and the assembled hollow rectangular pads are bonded to the pad mounting area (5).

6. The method for manufacturing a stacked potting structure of a rigid-flex substrate assembly according to claim 1, characterized in that: The area of ​​the hollow rectangular pad formed by the first pad (3) and the second pad (6) is equal to the area of ​​the rigid substrate (1) and the second pad (6) after bonding.

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 hollow rectangular pad formed by the first pad (3) and the second pad (6) is greater than the length of the final potted product.

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

10. A stacking potting structure of a rigid-flex substrate assembly, characterized in that: It is manufactured based on the stacking potting structure manufacturing method of any one of claims 1-9 of the rigid-flex substrate assembly.

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