Non-homogeneous multi-layered honeycomb-containing wave-absorbing sandwich structure and method of making same

Abstract

This invention provides a heterogeneous multi-layered honeycomb absorbing sandwich structure and its preparation method, comprising the following steps: Step S1, processing characteristic shapes at the same position on each panel of the sandwich structure; Step S2, processing side limiting grooves matching the characteristic shapes on an adhesive bonding fixture; Step S3, first assembly, with the assembly sequence starting from the panel with the larger coefficient of thermal expansion; Step S4, vacuum sealing except for the panel with the smaller coefficient of thermal expansion; Step S5, first curing; Step S6, second assembly, with the assembly sequence starting from the panel with the smaller coefficient of thermal expansion; Step S8, second curing after vacuum sealing. This invention uses lateral limiting blocks to precisely position each panel of the absorbing sandwich structure, ensuring the relative positional accuracy of each panel. The step-by-step curing method alleviates product bending deformation caused by inconsistent thermal deformation of the upper and lower panels, improving the flatness of the heterogeneous multi-layered absorbing sandwich structure.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, specifically to a heterogeneous microwave absorbing sandwich structure containing multiple honeycomb layers and its preparation method. Background Technology

[0002] By printing special carbon paste patterns on FR-4 panels, the panels can acquire specific electromagnetic properties. By assembling FR-4 panels with different printed carbon paste patterns in specific combinations, impedance characteristics can be utilized to create a structure with microwave absorption capabilities. By using multi-layer aramid paper honeycomb to support and composite the FR-4 panels, a microwave absorbing sandwich structure can be fabricated. Typically, one side of the microwave absorbing sandwich structure needs to be plated with copper foil for signal reflection, resulting in heterogeneous materials on both sides of the sandwich structure. Due to inconsistent thermal deformation, the flatness of the structure after molding is difficult to guarantee. Furthermore, to obtain specific impedance characteristics, the relative positional accuracy of each panel layer is required; panel misalignment can significantly reduce the structure's microwave absorption performance.

[0003] Therefore, the inventors believe that there is a need to provide a method for preparing a heterogeneous, multi-layered honeycomb-type microwave absorbing sandwich structure, which can achieve precise positioning of each layer of the microwave absorbing sandwich panel, thereby ensuring the relative positional accuracy of the printed patterns on each layer of the panel, and can alleviate the curing bending deformation caused by the inconsistency of the upper and lower panel materials, thus greatly improving the overall flatness of the microwave absorbing sandwich structure. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a heterogeneous, multi-layered honeycomb absorbing sandwich structure and its preparation method.

[0005] A method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure according to the present invention includes the following steps:

[0006] Step S1: Process the feature shape at the same position on each layer panel of the sandwich structure;

[0007] Step S2: Machining a side limiting groove on the adhesive bonding fixture that matches the shape of the feature;

[0008] Step S3: The sandwich structure is assembled for the first time on the adhesive bonding fixture. The two side panels of the sandwich structure have different coefficients of thermal expansion. The assembly sequence is to start assembling from the side panel with a larger coefficient of thermal expansion, with the side panel with a larger coefficient of thermal expansion facing down. When placing, the characteristic shape of each layer panel is embedded into the side limiting groove for limiting.

[0009] Step S4: Except for the panel with smaller thermal expansion, vacuum seal the other components of the sandwich structure after they are assembled.

[0010] Step S5: Place the packaged product into the curing equipment for the first curing.

[0011] Step S6: The sandwich structure is assembled for the second time on the adhesive bonding fixture. The assembly sequence is to start from the panel with the smaller coefficient of thermal expansion, with the panel with the smaller coefficient of thermal expansion facing down. When placing the panels, the characteristic shapes of each panel are embedded into the side limiting groove for positioning.

[0012] Step S7: After vacuum sealing the assembled sandwich structure, place it into a curing device for a second curing.

[0013] Preferably, the sandwich structure comprises multiple panels and a honeycomb core, and the materials of the two side panels of the sandwich structure are different.

[0014] Preferably, one side panel is an FR-4 bare board, and the other side is a single-sided copper-clad FR-4 panel.

[0015] Preferably, in step S2, the bonding fixture includes a positioning base plate, lateral limiting blocks, and fastening screws, and the two lateral limiting blocks are respectively fastened to the positioning base plate by the fastening screws.

[0016] Preferably, each of the lateral limiting blocks is provided with one or more of the lateral limiting grooves.

[0017] Preferably, the height of the side limiting groove is not lower than the height of the sandwich structure.

[0018] Preferably, in step S5, after the sandwich structure has completed its first curing, it is demolded and cleaned.

[0019] Preferably, in step S7, after the sandwich structure has completed its second curing, demolding and cleaning are performed.

[0020] The present invention provides a heterogeneous multi-layered honeycomb absorbing sandwich structure, which is prepared by the above-described method for preparing a heterogeneous multi-layered honeycomb absorbing sandwich structure.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention uses specially designed lateral limiting blocks to precisely position each panel of the microwave absorbing sandwich structure, ensuring the relative positional accuracy of each panel. It also employs a step-by-step curing method to alleviate product bending deformation caused by inconsistent thermal deformation of the upper and lower panels, thereby improving the flatness of the heterogeneous multilayer microwave absorbing sandwich structure. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the adhesive bonding fixture, which is the main feature of this invention.

[0025] As shown in the figure:

[0026] Positioning base plate 1 Lateral limiting block 2 Fastening screw 3 Detailed Implementation

[0027] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0028] Example 1

[0029] like Figure 1 As shown, a method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure according to the present invention includes the following steps:

[0030] Step S1: Based on the characteristics of each layer panel of the sandwich structure, process the feature shape at the same position of each layer panel of the sandwich structure.

[0031] Step S2: Machining a side limiting groove that matches the feature shape on the bonding fixture for limiting the panel during bonding assembly;

[0032] Step S3: The sandwich structure is assembled for the first time on the adhesive bonding fixture. The two panels of the sandwich structure have different coefficients of thermal expansion. The assembly sequence is to start assembling from the panel with the larger coefficient of thermal expansion. The panel with the larger coefficient of thermal expansion faces down. When placing, the characteristic shape of each panel is embedded into the side limiting groove for limiting.

[0033] Step S4: Except for the panel with smaller thermal expansion, vacuum seal the other components of the sandwich structure after they are assembled.

[0034] Step S5: Place the packaged product into the curing equipment for the first curing, and demold and clean the sandwich structure after the first curing.

[0035] Step S6: Perform the second assembly of the sandwich structure on the adhesive bonding fixture. The assembly sequence is to start assembling from the panel with the smaller coefficient of thermal expansion, with the panel with the smaller coefficient of thermal expansion facing down. When placing the panels, embed the characteristic shape of each panel into the side limiting groove for positioning.

[0036] Step S8: After vacuum sealing the assembled sandwich structure, place it in a curing device for a second curing, and then demold and clean the sandwich structure after the second curing.

[0037] The sandwich structure comprises multiple layers of panels and a honeycomb core. During curing, misalignment may occur between the honeycomb core layers and the panels, making it difficult to guarantee the relative positions of each layer. The panels on both sides of the sandwich structure are made of different materials; one side is an FR-4 bare panel, and the other is a single-sided copper-clad FR-4 panel. Due to inconsistent deformation during curing, the structure may bend to one side after curing using conventional methods. To ensure the flatness of the structure during curing, a step-by-step curing method is employed.

[0038] In step S2, the bonding fixture includes a positioning base plate 1, lateral limiting blocks 2, and fastening screws 3. Two lateral limiting blocks 2 are respectively fastened to the positioning base plate 1 by the fastening screws 3, achieving precise positioning of the multi-layer structure. The lateral limiting blocks 2 have grooves machined in the panel feature shape areas, and each lateral limiting block 2 has one or more side limiting grooves. The components of each layer of the sandwich structure are assembled sequentially on the positioning base plate 1. During placement, the feature shapes of each panel layer are embedded into the grooves in the feature shape areas of the lateral limiting blocks 2 for positioning, ensuring panel positioning accuracy. The height of the side limiting grooves is not less than the overall height of the sandwich structure. Furthermore, in practical applications, the number and position of the lateral limiting blocks 2, as well as the number and position of the side limiting grooves, can be adjusted according to actual needs.

[0039] This application uses a specially designed lateral limiting block 2 to precisely position each panel of the microwave absorbing sandwich structure, ensuring the relative position accuracy of each panel. It also adopts a step-by-step curing method to alleviate the bending deformation of the product caused by inconsistent thermal deformation of the upper and lower panels, thereby improving the flatness of the non-homogeneous multilayer microwave absorbing sandwich structure.

[0040] Example 2

[0041] A heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure is prepared using the method described in Example 1. This method enables high-precision bonding and molding of a microwave absorbing sandwich structure containing multi-layered aramid paper honeycomb and FR-4 panels, with the upper and lower panels being made of dissimilar materials. The bonding method utilizes specialized tooling for precise positioning of each FR-4 panel layer and employs a step-by-step curing approach to mitigate the impact of the dissimilar materials on the flatness of the sandwich structure. This ensures the relative positional accuracy of each panel layer and improves the flatness of the molded sandwich structure. Using this method guarantees high-precision bonding and molding of the heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure, mitigates bending deformation caused by inconsistent materials on both sides of the structure, and improves the surface flatness performance of the product.

[0042] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0043] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure, characterized in that, Includes the following steps: Step S1: Process the feature shape at the same position on each layer panel of the sandwich structure; Step S2: Machining a side limiting groove on the adhesive bonding fixture that matches the shape of the feature; Step S3: The sandwich structure is assembled for the first time on the adhesive bonding fixture. The two side panels of the sandwich structure have different coefficients of thermal expansion. The assembly sequence is to start assembling from the side panel with a larger coefficient of thermal expansion. The side panel with a larger coefficient of thermal expansion faces down. When placing, the characteristic shape of each layer panel is embedded into the side limiting groove for limiting. Step S4: Except for the panel with smaller thermal expansion, vacuum seal the other components of the sandwich structure after they are assembled. Step S5: Place the packaged product into the curing equipment for the first curing. Step S6: The sandwich structure is assembled for the second time on the adhesive bonding fixture. The assembly sequence is to start from the panel with the smaller coefficient of thermal expansion, with the panel with the smaller coefficient of thermal expansion facing down. When placing the panels, the characteristic shapes of each panel are embedded into the side limiting groove for positioning. Step S7: After vacuum sealing the assembled sandwich structure, place it into a curing device for a second curing.

2. The method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure as described in claim 1, characterized in that, The sandwich structure comprises multiple panels and a honeycomb core, and the materials of the two side panels of the sandwich structure are different.

3. The method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure as described in claim 2, characterized in that, One side panel is an FR-4 bare board, and the other side is a single-sided copper-clad FR-4 panel.

4. The method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure as described in claim 1, characterized in that, In step S2, the bonding fixture includes a positioning base plate (1), a lateral limiting block (2), and a fastening screw (3). The two lateral limiting blocks (2) are respectively fastened to the positioning base plate (1) by the fastening screw (3).

5. The method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure as described in claim 4, characterized in that, Each of the lateral limiting blocks (2) is provided with one or more of the lateral limiting grooves.

6. The method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure as described in claim 1, characterized in that, The height of the side limiting groove is not lower than the height of the sandwich structure.

7. The method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure as described in claim 1, characterized in that, In step S5, after the sandwich structure has completed its first curing, it is demolded and cleaned.

8. The method for preparing a heterogeneous, multi-layered honeycomb-containing microwave absorbing sandwich structure as described in claim 1, characterized in that, In step S7, after the sandwich structure has completed its second curing, it is demolded and cleaned.

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