Weldable conductive heat-dissipating cushion foam

Abstract

The utility model discloses a kind of weldable conductive heat-dissipating buffer foam, including foam core, silica gel layer, annular PI glue layer adhered in the outer side of foam core by silica gel layer, annular copper foil layer being arranged in the outer side of annular PI glue layer, annular nickel plating layer being arranged in the outer side of annular copper foil layer, annular welding layer being arranged in the outer surface of annular nickel plating layer, the welding layer is tinning layer or gold plating layer.Advantages: annular tinning layer or gold plating layer has good weldability, can guarantee that the foam of the application is stably welded on PCB mainboard.At the same time, annular tinning layer or gold plating layer, annular copper foil layer and annular nickel plating layer have good conductivity, by one side and PCB connection other side and shell are offset, can realize shielding ground;Utilize the elasticity of foam core and annular PI layer, can be elastically deformed when shell is impacted, realize the buffer protection to PCB mainboard.The structure of entire product is less, preparation process is simple, and it is not easy to delaminate.

Description

Technical Field

[0001] This utility model relates to the field of cushioning foam, specifically a weldable, conductive, heat-dissipating cushioning foam. Background Technology

[0002] In the assembly and operation of PCB motherboards for electronic devices, especially precision electronic devices, components with conductive and buffering functions are often required to achieve grounding shielding, structural buffering, and signal conduction. Currently, the mainstream such components on the market include beryllium copper springs and solderable conductive foam. While beryllium copper springs possess good conductivity and a certain degree of buffering performance, their processing cost is high, and strict assembly precision is required during installation. Assembly deviations can easily lead to poor contact, thus affecting conductivity. Furthermore, beryllium copper springs have poor heat dissipation performance, failing to meet the timely heat dissipation requirements of the PCB motherboard during operation. Long-term use can lead to heat accumulation, affecting the lifespan and operational stability of electronic components. Some existing buffer foams have deficiencies in tear resistance, high-temperature resistance (especially in reflow soldering environments), flame retardancy, and resilience. For example, they are prone to breakage during repeated compression, failing to meet the requirements for long-term stable operation of electronic devices; their flame retardancy does not meet the UL94V-0 standard, posing a safety hazard. Furthermore, existing encapsulated foams use a variety of outer packaging materials and have complex manufacturing processes. Additionally, the existing structure is prone to delamination due to the different physicochemical properties of the materials.

[0003] For example, Chinese patent CN220390523U discloses a wrap-around, weldable, conductive, and heat-dissipating cushioning foam, including a foam core. The foam core is surrounded by a conductive and heat-dissipating composite material, which includes a PI layer. A tin-plated layer is disposed on one side of the PI layer, and a high-temperature resistant self-adhesive layer is disposed on the other side of the PI layer. A graphite layer is disposed on the side of the high-temperature resistant self-adhesive layer away from the PI layer. A self-adhesive layer is disposed on the side of the graphite layer away from the high-temperature resistant self-adhesive layer. A PET layer is disposed on the side of the self-adhesive layer away from the graphite layer. A hot-melt adhesive layer is disposed on the side of the PET layer away from the self-adhesive layer, and the hot-melt adhesive layer is bonded to the outer surface of the foam core. In the aforementioned patent, the structure is complex; the graphite layer, high-temperature resistant self-adhesive layer, self-adhesive layer, PET layer, and hot-melt adhesive layer are all independent materials. A composite layering device is required to wrap the foam core, making the process relatively complex. Furthermore, the tin plating layer is directly connected to the PI layer. The coefficient of thermal expansion of tin is about 23 ppm / ℃, while the coefficient of thermal expansion of the PI layer is about 30-50 ppm / ℃. The two materials have a large difference in the coefficient of thermal expansion. At the same time, the tin surface is easy to oxidize, forming a dense tin oxide film, which can easily lead to delamination after the tin plating layer and the PI layer are connected.

[0004] Therefore, it is necessary to provide a weldable conductive heat dissipation cushioning foam. Utility Model Content

[0005] This invention provides a weldable conductive heat dissipation cushioning foam, which effectively solves the problems of complex manufacturing process and easy delamination of existing cushioning foams.

[0006] The technical solution adopted in this utility model is:

[0007] A weldable conductive heat dissipation cushioning foam includes a foam core, a silicone layer, an annular PI adhesive layer bonded to the outside of the foam core by the silicone layer, an annular copper foil layer disposed on the outside of the annular PI adhesive layer, an annular nickel plating layer disposed on the outside of the annular copper foil layer, and an annular welding layer disposed on the outer surface of the annular nickel plating layer, wherein the welding layer is a tin plating layer or a gold plating layer.

[0008] Furthermore, the thickness of the tin-plated layer or gold-plated layer ranges from 0.1µm to 3µm.

[0009] Furthermore, the thickness of the annular nickel plating layer ranges from 0.3 μm to 2 μm.

[0010] Furthermore, the thickness of the annular copper foil layer ranges from 0.01 mm to 0.025 mm.

[0011] Furthermore, the thickness of the annular PI adhesive layer ranges from 0.005 mm to 0.02 mm.

[0012] Furthermore, the thickness of the silicone layer ranges from 0.02 mm to 0.05 mm.

[0013] Furthermore, the thickness of the foam core ranges from 0.5mm to 20mm.

[0014] The beneficial effects of this utility model are as follows: The annular tin-plated or gold-plated layer has good solderability, ensuring that the foam of this application is stably soldered onto the PCB motherboard. Simultaneously, the annular tin-plated or gold-plated layer, the annular copper foil layer, and the annular nickel-plated layer have good conductivity. By connecting one side to the PCB and the other side abutting against the outer casing, shielding and grounding can be achieved. The elasticity of the foam core and the annular PI layer allows for elastic deformation when the outer casing is impacted, providing cushioning protection for the PCB motherboard. The overall product structure is simplified, resulting in a simple manufacturing process. Delamination is less likely between the PI adhesive layer and the annular copper foil layer, and between the annular copper foil layer, the annular nickel-plated layer, and the annular solder layer. Attached Figure Description

[0015] Figure 1 This is an overall schematic diagram of the weldable conductive heat dissipation cushioning foam provided in an embodiment of this application.

[0016] The markings in the diagram are: 1. Foam core; 2. Silicone layer; 3. Annular PI layer; 4. Annular copper foil layer; 5. Annular nickel plating layer; 6. Annular solder layer. Detailed Implementation

[0017] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, the embodiment of this application provides a solderable conductive heat dissipation cushioning foam, including a foam core 1, a silicone layer 2, an annular PI adhesive layer bonded to the outside of the foam core 1 by the silicone layer 2, an annular copper foil layer 4 disposed on the outside of the annular PI adhesive layer, an annular nickel plating layer 5 disposed on the outside of the annular copper foil layer 4, and an annular welding layer 6 disposed on the outer surface of the annular nickel plating layer 5, wherein the annular welding layer 6 is a tin plating layer or a gold plating layer.

[0019] In actual preparation, a nickel layer is first electroplated on the outside of the copper foil layer, and then a tin or gold layer is electroplated on the nickel layer. Then, PI adhesive is applied to the inside of the copper foil layer to cure the PI adhesive inside the copper foil layer, so that the PI adhesive layer, copper foil layer, nickel plating layer and annular welding layer 6 form an integrated outer packaging material. Then, the outer packaging material is wrapped with PI adhesive layer on the silicone layer 2 on the outer surface of foam core 1 to form annular copper foil layer 4, annular nickel plating layer 5 and annular welding layer 6.

[0020] In practical applications, the annular soldering layer 6 is soldered to the PCB motherboard to achieve the connection between the solderable conductive heat dissipation buffer foam of this application and the PCB motherboard, and then abuts against the outer shell. When the PCB motherboard is working, a very small portion of the heat generated is dissipated through the annular soldering layer 6, and the remaining heat is transferred to the annular nickel plating layer 5. After a very small portion of the heat transferred to the annular nickel plating layer 5 is dissipated, the remaining heat is transferred to the annular copper foil layer 4. After most of the heat transferred to the annular copper foil layer 4 is dissipated, the remaining heat is transferred through the annular PI adhesive layer and silicone layer 2 to the foam core 1 (the copper foil substrate has a high thermal conductivity (≥380W / (m·K)) and can quickly conduct the heat generated by the PCB motherboard). Since the two ends of the foam core 1 are exposed and the foam has micropores, it can use the micropores to form convection with the air in the equipment space to dissipate heat. In actual use, the outer casing may be subjected to external impacts. The outer casing compresses the annular welding layer 6, causing compression on one side of the annular welding layer 6, the annular nickel plating layer 5, and the annular copper foil layer 4. Then, the PI layer is elastically compressed on the opposite side of the outer casing. After compression, the foam core 1 elastically contracts, preventing the impact from causing deformation on the side of the annular welding layer 6, the annular nickel plating layer 5, and the annular copper foil layer 4 corresponding to the PCB board. Meanwhile, copper (Cu) and tin (Sn) have similar atomic radii (Cu approximately 135 pm, Sn approximately 145 pm) and high chemical reactivity matching. At room temperature, they slowly undergo atomic interdiffusion to form Cu-Sn intermetallic compounds (such as Cu:Sn, CuSn). These compounds are brittle and hard, which can disrupt the interfacial bonding between copper and tin, leading to plating cracking. However, the interdiffusion rate between nickel and copper is much lower than that between copper and tin (at room temperature, the diffusion rate of Cu-Sn is 10-100 times that of Cu-Ni), and the diffusion reaction between nickel and tin requires higher temperatures (usually >200℃) to occur significantly. Therefore, completely blocking the path of copper atoms diffusing into the tin layer and tin atoms penetrating into the copper substrate makes copper, nickel, and tin more stable and less prone to delamination. When the PCB motherboard is powered on, current is transferred through the annular solder layer 6, the annular nickel plating layer 5, and the annular copper foil layer 4, allowing the current to be transferred from the side opposite to the PCB motherboard to the outer casing, achieving grounding shielding. When the PI adhesive layer bonds with the copper foil, the surface of the copper foil will oxidize to form copper oxide or cuprous oxide, which has chemical reactivity. The oxygen atoms on their surface can act as "anchors," forming coordination or ionic bonds with functional groups on the PI molecular chain (such as carbonyl C=O and imine -N-). Compared to the PI adhesive layer and tin, which are mainly connected by van der Waals forces, the bond between copper foil and PI adhesive is much stronger, thus greatly improving anti-delamination ability and long-term reliability. Furthermore, copper, nickel, tin, or gold can be bonded through electroplating, which has high strength, making delamination less likely.

[0021] In the above design, the annular tin-plated or gold-plated layer has good solderability, ensuring that the foam of this application is stably soldered onto the PCB motherboard. Simultaneously, the annular tin-plated or gold-plated layer, the annular copper foil layer 4, and the annular nickel-plated layer 5 have good conductivity. By connecting one side to the PCB and the other side abutting against the outer casing, shielding and grounding can be achieved. The elasticity of the foam core 1 and the annular PI layer 3 allows for elastic deformation when the outer casing is impacted, providing buffer protection for the PCB motherboard. The overall product structure is minimal, resulting in a simple manufacturing process. Delamination is less likely between the PI adhesive layer and the annular copper foil layer 4, and between the annular copper foil layer 4, the annular nickel-plated layer 5, and the annular solder layer 6.

[0022] Specifically, the thickness of the tin plating layer or gold plating layer ranges from 0.1µm to 3µm.

[0023] In the above design, the thickness of the tin plating layer or gold plating layer ranges from 0.1um to 3um to meet the requirements of product thinning.

[0024] Specifically, the thickness of the annular nickel plating layer 5 ranges from 0.3 μm to 2 μm.

[0025] In the above design, the thickness of the annular nickel plating layer 5 ranges from 0.3um to 2um, which meets the requirements of product thinning and can also take advantage of the corrosion resistance and surface hardness of nickel, as well as the bonding between the copper foil and the tin or gold layer, to avoid oxidation or uneven plating of the copper foil during subsequent processing and use.

[0026] Specifically, the thickness of the annular copper foil layer 4 ranges from 0.01 mm to 0.025 mm.

[0027] In the above design, the thickness of the annular copper foil layer 4 is in the range of 0.01mm to 0.025mm, which can meet the requirements of product thinness. At the same time, it can utilize the good conductivity of copper foil for conduction and the good thermal conductivity of copper foil for heat dissipation.

[0028] Specifically, the thickness of the annular PI adhesive layer ranges from 0.005 mm to 0.02 mm.

[0029] It should be noted that PI adhesive is not tacky at room temperature. In this application, liquid PI adhesive is applied to a copper foil substrate and cured into a film.

[0030] In the above design, the thickness range of the annular PI adhesive layer is 0.005mm to 0.02mm, which meets the requirements for product thinness. Simultaneously, the properties of PI adhesive (non-adhesive at room temperature) allow it to cure into a film on the copper foil surface, thereby improving the tear resistance of the copper foil and preventing breakage due to external forces during foam processing, transportation, and use. Furthermore, PI adhesive possesses excellent high-temperature resistance, withstanding the high temperatures of reflow soldering without melting, deformation, or decomposition. Compared to conventional PI film, PI adhesive also offers superior flexibility, preventing the high strength of PI film from causing tangling and resulting in inadequate foam wrapping and delamination.

[0031] Specifically, the thickness of the silicone layer 2 ranges from 0.02 mm to 0.05 mm. The silicone used is high-temperature resistant silicone.

[0032] In the above design, the thickness of the silicone layer 2 ranges from 0.02mm to 0.05mm, which not only meets the requirements of product thinness, but also utilizes the good adhesion properties of the silicone layer 2 to achieve a stable connection between the PI adhesive layer and the foam core 1 layer. At the same time, the high-temperature resistant silicone has excellent high-temperature resistance (can withstand reflow soldering high temperature of 260-300℃) and elasticity, which can help the core layer to achieve a cushioning function, and further improve the overall high-temperature resistance and flame retardant properties of the foam.

[0033] Specifically, the thickness of the foam core 1 ranges from 0.5mm to 20mm.

[0034] In the above design, the foam core 1 can be made of extruded silicone foam or expanded silicone foam, and the thickness of the core layer is set to 0.5-20mm according to the actual installation requirements of the PCB motherboard. Extruded silicone foam has a closed-cell structure; in practical applications, different shaped openings are typically placed in the middle of the silicone core to reduce compression rebound force and improve resilience. Expanded silicone foam has a uniform microporous structure inside. This microporous structure not only provides excellent cushioning performance, ensuring that the foam can generate effective elastic deformation when compressed, achieving a cushioning effect, but also, the silicone material itself has certain thermal conductivity. Combined with the air convection in the microporous structure, it can assist in the conduction and dissipation of heat, improving the overall heat dissipation efficiency of the foam. Furthermore, the silicone material used in the core layer undergoes special modification treatment, possessing high resilience (resilience >85%) and fatigue resistance, ensuring that the foam does not break during repeated compression; and the flame retardant performance of this silicone material meets the UL94V-0 standard, improving the safety performance of the foam.

[0035] In further detail, it should be understood that the above description is only a specific embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A weldable conductive heat-dissipating cushioning foam, characterized in that: It includes a foam core (1), a silicone layer (2), an annular PI adhesive layer bonded to the outside of the foam core (1) by the silicone layer (2), an annular copper foil layer (4) disposed on the outside of the annular PI adhesive layer, an annular nickel plating layer (5) disposed on the outside of the annular copper foil layer (4), and an annular welding layer (6) disposed on the outer surface of the annular nickel plating layer (5), wherein the annular welding layer (6) is a tin plating layer or a gold plating layer.

2. The weldable conductive heat dissipation cushioning foam according to claim 1, characterized in that: The thickness of the tin-plated or gold-plated layer ranges from 0.1µm to 3µm.

3. The weldable conductive heat dissipation cushioning foam according to claim 1, characterized in that: The thickness of the annular nickel plating layer (5) ranges from 0.3 μm to 2 μm.

4. The weldable conductive heat dissipation cushioning foam according to claim 1, characterized in that: The thickness of the annular copper foil layer (4) ranges from 0.01 mm to 0.025 mm.

5. The weldable conductive heat dissipation cushioning foam according to claim 1, characterized in that: The thickness of the annular PI adhesive layer ranges from 0.005 mm to 0.02 mm.

6. The weldable conductive heat dissipation cushioning foam according to claim 1, characterized in that: The thickness of the silicone layer (2) ranges from 0.02 mm to 0.05 mm.

7. The weldable conductive heat dissipation cushioning foam according to claim 1, characterized in that: The thickness of the foam core (1) ranges from 0.5 mm to 20 mm.

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