High-conductivity cushioning foam with controllable deformation direction

Abstract

This invention discloses a high-conductivity cushioning foam with controllable deformation direction, comprising: a polyurethane foam core material; a conductive cloth wrapped around the outer surface of the polyurethane foam core material to form a cushioning foam pad; a partial double-sided adhesive layer disposed at one end of the bottom region of the cushioning foam pad, the other end of the bottom region of the cushioning foam pad being an adhesive-free conductive area; and a rounded corner guide structure disposed on the longitudinal side of the top of the cushioning foam pad, the same as the partial double-sided adhesive layer. This invention achieves high conductivity and stable grounding by forming a purely physical conductive path through the partially adhesive-free area at the bottom, while simultaneously controlling the direction of deformation under pressure using the rounded corner guide structure on one side of the top, avoiding interference with surrounding components. Thus, it simultaneously ensures conductive reliability and spatial safety within the confined space of a laptop's lower casing.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding and buffering technology for electronic devices, and specifically relates to a high-conductivity buffer foam with controllable deformation direction. Background Technology

[0002] Currently, in portable electronic devices such as laptops, conductive cushioning foam is typically installed between the motherboard and the chassis inside the lower casing to meet requirements for electromagnetic shielding, electrostatic protection, and structural cushioning. This type of conductive cushioning foam needs to simultaneously perform two functions within a confined space: low-impedance conductive grounding and pressure-bearing cushioning.

[0003] Existing conductive cushioning foam typically employs a composite structure of conductive cloth and foam core material, and is fixed to a designated location on the lower casing or motherboard of a laptop using adhesive. However, this type of product still has the following shortcomings in practical applications: Firstly, the conduction impedance is unstable. Currently, conductive foam is typically attached to external conductors using conductive adhesive or double-sided tape during assembly. While conductive adhesive has some conductivity, its own impedance is relatively high and significantly affected by factors such as temperature and pressure, essentially creating an unstable resistive element in series in the conductive path. This results in a high and fluctuating overall conduction impedance when current flows from the top of the foam through the adhesive layer to the bottom conductor, making it difficult to meet the low impedance and high stability grounding requirements of the delicate circuitry inside a laptop.

[0004] Secondly, lateral bulging poses a risk of interference. Inside the lower casing of a laptop, conductive cushioning foam is typically compressed and installed in the narrow gap between the motherboard and the chassis, an area often densely packed with various electronic components. Existing conductive foams are mostly regular cuboid structures; when compressed in the thickness direction, they can produce uncontrollable, random lateral bulging deformation. Due to the lack of guidance and control over the direction of this bulging, it may compress adjacent flexible circuit boards, connectors, or other sensitive components, causing physical damage or poor contact.

[0005] In summary, how to effectively control the lateral deformation direction of conductive buffer foam under pressure while ensuring that it has low and stable on-resistance, and avoid interference with surrounding components, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a high-conductivity buffer foam with controllable deformation direction. This invention achieves high conductivity and stable grounding by forming a purely physical conductive path through a partially glue-free area at the bottom. Simultaneously, it utilizes a single-sided rounded corner guide structure at the top to control the direction of deformation under pressure, avoiding interference with surrounding components. Thus, it simultaneously ensures conductive reliability and spatial safety within the confined space of a laptop's lower casing.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution: A high-conductivity cushioning foam with controllable deformation direction, comprising: Polyurethane foam core material; Conductive cloth is wrapped around the outer surface of the polyurethane foam core material to form a cushioning foam pad. A partial double-sided adhesive layer is provided at one end of the bottom area of ​​the cushioning foam pad, while the other end of the bottom area of ​​the cushioning foam pad is an adhesive-free conductive area. A rounded corner guide structure is provided on the longitudinal side of the top of the cushioning foam pad, which is the same as the partial double-sided adhesive layer.

[0008] Furthermore, the rounded corner guide structure is located above the partial double-sided adhesive layer. When the cushioning foam pad is subjected to compressive force, the lateral bulging deformation of the polyurethane foam core material occurs on the side where the rounded corner guide structure is located.

[0009] Furthermore, the width of the partial double-sided adhesive layer covering one end of the bottom area accounts for 30% to 70% of the total bottom width.

[0010] Furthermore, the conductive cloth comprises an outer copper-nickel conductive coating and an inner polyester fiber fabric, and the thickness of the conductive cloth is 0.05mm to 0.08mm.

[0011] Furthermore, the planar resistance of the conductive cloth is less than 0.07 Ω / sq.

[0012] Furthermore, when the cushioning foam pad is compressed, the adhesive-free conductive area forms a purely physical conductive path from the top of the cushioning foam pad through the conductive cloth to the bottom of the cushioning foam pad, thereby avoiding the resistance interference of the local double-sided adhesive layer.

[0013] Furthermore, when the height of the cushioning foam pad is compressed to 2.81 mm, the impedance of the conductive path through the adhesive-free conductive area does not exceed 0.07 ohms.

[0014] Furthermore, when the height of the cushioning foam pad is compressed to 4.46mm, the rounded corner guide structure forces the polyurethane foam core material to bulge and deform only on the side where the rounded corner guide structure is located, and the rebound force of the cushioning foam pad does not exceed 1.6N.

[0015] Preferably, the partial double-sided adhesive layer is an acrylic pressure-sensitive tape with a 180-degree peel strength greater than 1.45 N / mm.

[0016] Furthermore, the cushioning foam is applied to the narrow space inside the lower casing of the laptop computer to provide conductive grounding and cushioning between the lower casing of the laptop computer and the motherboard or electronic components.

[0017] The beneficial effects of this invention are as follows: This invention features a partial double-sided adhesive layer at the bottom of the cushioning foam, with the un-adhesive area serving as a non-adhesive conductive zone. When current flows from the top to the bottom of the cushioning foam, this non-adhesive zone forms a conductive path consisting solely of conductive fabric, bypassing any adhesive layer. Since adhesive layers have high impedance and are susceptible to fluctuations due to ambient temperature and humidity, this solution eliminates these unstable factors from the conductive path by creating a non-adhesive conductive zone. Combined with the conductive fabric's planar resistance being below 0.07 Ω / sq, this results in a lower and more stable overall conductive impedance.

[0018] This invention features a rounded corner guide structure on one side of the top of the cushioning foam, while the other side has a right angle or no rounded corner structure. When the cushioning foam is compressed in the thickness direction, the material on the rounded corner side experiences less resistance to lateral flow, while the other side, constrained by the conductive fabric folds, experiences greater resistance to material flow. Thus, lateral bulging of the foam is guided to occur on the rounded corner side, while the other side remains largely undeformed, thereby avoiding compression interference with components on that side. When applied to the confined space inside the lower casing of a laptop, this ensures that the deformation direction faces an open area of ​​the casing or the reinforcing ribs, thus avoiding nearby sensitive electronic components such as flexible circuit boards, connectors, and batteries, eliminating the risk of physical damage or poor contact caused by lateral compression.

[0019] The partial double-sided adhesive layer provides bonding and fixation between the cushioning foam and the lower casing or motherboard of the laptop, preventing displacement of the product during assembly and use. The adhesive layer uses a high-viscosity adhesive with a peel strength greater than 1.45 N / mm, meeting the fixation strength requirements of the internal components of the laptop.

[0020] This invention achieves functional complementarity through a spatial partitioning layout of "partial adhesive-free conduction" and "single-sided rounded corner guidance": the partially adhesive-free area constructs a purely physical conductive path on one side of the bottom, avoiding interference from the adhesive layer and ensuring low-impedance conduction; the single-sided rounded corner forcibly guides the pressure bulge to the opposite side at the top, preventing lateral bulging deformation on the side where the adhesive-free area is located, thereby ensuring the stability of the conductive contact surface on that side. Both mechanisms independently perform the functions of conduction and deformation guidance during the same compression process, simultaneously addressing the dual requirements of constructing a low-impedance conductive path and controlling lateral deformation space. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the high conductivity buffer foam of the present invention.

[0022] Figure 2 This is a side view of the high-conductivity buffer foam of the present invention.

[0023] In the diagram, 1: polyurethane foam core material; 2: conductive cloth; 3: partial double-sided adhesive layer; 4: rounded corner guide structure. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a high-conductivity cushioning foam with controllable deformation direction, used for placement between the lower shell of a laptop and the motherboard or electronic components, providing conductive grounding, cushioning and shock absorption, and deformation direction control functions. The cushioning foam includes a polyurethane foam core 1, a conductive cloth 2, a partial double-sided adhesive layer 3, and a rounded corner guide structure 4.

[0026] The polyurethane foam core 1 and the conductive cloth 2 constitute the cushioning foam pad. The polyurethane foam core 1 provides support and cushioning for the entire pad. The conductive cloth 2 wraps around the outer surface of the polyurethane foam core 1, forming the outer conductive layer of the cushioning foam pad.

[0027] The polyurethane foam core material 1 is made from polyurethane foam material through a foaming molding process, and its interior has a uniformly distributed microporous structure. This microporous structure gives the polyurethane foam core material 1 compression resilience, resistance to compression fatigue, and energy absorption capacity. When the lower shell of the laptop is subjected to external impact or vibration, the polyurethane foam core material 1 absorbs and disperses the impact energy through the compression deformation of its own micropores, attenuating the vibration and impact loads transmitted to the motherboard and electronic components, thereby achieving a shock absorption and buffering function. The microporous structure gives the polyurethane foam core material 1 good flexibility, making it less prone to permanent compression deformation during repeated compression and rebound cycles.

[0028] The density range of polyurethane foam core material 1 is 30~55 kg / m³. 3 When the density is too low, the micropore walls of the foam are too thin, resulting in insufficient structural strength. This makes it prone to collapse or permanent deformation after long-term compression. When the density is too high, the micropore structure of the foam is too dense, leading to excessive compression rigidity and increased rebound force, which can cause excessive assembly stress on surrounding components. The ideal density is controlled between 30 and 55 kg / m³. 3 Within the specified range, the compression rebound force can be controlled while ensuring the support contact pressure.

[0029] For example, the polyurethane foam core material 1 is prepared by foaming a foaming material containing the following raw materials in parts by weight: 100-110 parts of toluene diisocyanate, 40-50 parts of polyether polyol, 40-45 parts of polyether alcohol, 2-4 parts of water, and 3-5 parts of silicone oil.

[0030] Conductive cloth 2 uses polyester fiber fabric as the base material, and its surface has a black copper-nickel conductive coating, which makes the fabric surface conductive.

[0031] The total thickness of the conductive cloth 2 is 0.05mm to 0.08mm. Within this thickness range, the conductive cloth 2 has sufficient mechanical strength and is not easily broken during wrapping and compression, while also possessing good flexibility, facilitating bending and bonding when wrapping the polyurethane foam core material 1. When the thickness of the conductive cloth 2 is less than 0.05mm, its tensile strength and puncture resistance are insufficient, making it prone to damage during wrapping, bending, or long-term compression; when the thickness is greater than 0.08mm, the flexibility of the conductive cloth 2 decreases, making it prone to creases during bending and difficult to tightly adhere to the outer surface of the foam core material.

[0032] The planar resistance of conductive cloth 2 is less than 0.07 Ω / sq. Planar resistance characterizes the conductivity of conductive cloth 2 along its surface. Maintaining the planar resistance to less than 0.07 Ω / sq results in low self-resistance loss for conductive cloth 2. When the cushioning foam is compressed, current flows along the surface of conductive cloth 2 from the top to the bottom of the pad; the low planar resistance reduces the voltage drop along the conduction path.

[0033] The outer surface of the conductive cloth 2 is black. The black appearance is hidden inside the casing after assembly inside the laptop, and at the same time, it facilitates the inspection of the wrapping quality of the conductive cloth 2 using optical inspection methods.

[0034] The conductive cloth 2 is bonded to the polyurethane foam core material 1 by hot pressing or cold pressing, so that the conductive cloth 2 is attached to the outer surface of the foam core material.

[0035] A partial double-sided adhesive layer 3 is set at one end of the bottom area of ​​the cushioning foam pad, while no double-sided adhesive layer is set at the other end of the bottom area of ​​the cushioning foam pad, forming an adhesive-free conductive area.

[0036] Preferably, at the end where the partial double-sided adhesive layer 3 is provided, the conductive cloth 2 extends outward and protrudes when wrapped, and the partial double-sided adhesive layer 3 also extends outward and protrudes, so that the lateral contour of the cushioning foam at this end is an L-shaped structure, thereby increasing the bonding area through the bottom adhesive layer extension section and improving the fixing reliability.

[0037] The partial double-sided adhesive layer 3 is preferably made of double-sided coated acrylic pressure-sensitive tape, which uses PET film as the substrate, with both sides of the PET film coated with acrylic pressure-sensitive adhesive. The PET film substrate provides the tape with dimensional stability and tensile strength; the acrylic pressure-sensitive adhesive adheres to the target surface when pressure is applied. The partial double-sided adhesive layer 3 is an acrylic pressure-sensitive tape, which is adaptable to the adhesion of magnesium-aluminum alloys, stainless steel, and sprayed surfaces, and has temperature resistance and aging resistance.

[0038] The width of the partial double-sided adhesive layer 3 covering one end of the bottom area is 30% to 70% of the total bottom width. Designing the adhesive layer coverage width to be no less than 30% of the total bottom width ensures sufficient bonding area between the adhesive layer and the bottom shell surface, providing lasting fixation. The adhesive layer coverage width to be no more than 70% of the total bottom width ensures sufficient width in the adhesive-free conductive area, guaranteeing stable physical contact between the conductive fabric 2 in this area and the grounding part of the bottom shell.

[0039] The adhesive-free conductive area completely exposes the surface of the conductive cloth 2, leaving it uncovered by adhesive material. Current flows along the surface of the conductive cloth 2 from the top of the pad to the bottom adhesive-free conductive area, forming a purely physical conductive path from the top of the pad through the conductive cloth 2 directly to the bottom, without passing through any double-sided adhesive layer. This eliminates the additional contact resistance introduced by the adhesive layer. Furthermore, this conductive path does not change with adhesive aging.

[0040] The 180-degree peel force of the partial double-sided adhesive layer 3 is greater than 1.45 N / mm. This peel force level ensures that the adhesive layer has sufficient bonding strength with the bottom shell of the notebook or the surface of the motherboard, so that the cushioning foam remains fixed under vibration and temperature change conditions and does not slip or fall off horizontally.

[0041] The rounded corner guide structure 4 is located on the same longitudinal side as the partial double-sided adhesive layer 3 on the top of the cushioning foam pad. That is, the rounded corner guide structure 4 is located above the end of the pad near the partial double-sided adhesive layer 3, and the two are on the same side in the longitudinal direction. The other longitudinal side of the top of the cushioning foam pad is a right-angle structure or a structure without rounded corners.

[0042] When the cushioning foam pad is subjected to a vertical compressive force, compressive stress is generated inside the polyurethane foam core material 1. On one side of the pad with a rounded corner guide structure 4, the edge of which is a rounded curved surface transition, the stress forms a tangential component at the rounded curved surface. When the foam material is compressed, it undergoes lateral displacement along the tangent of the rounded curved surface; the rounded curved surface provides displacement space for the lateral extrusion of the foam material on this side.

[0043] On the other longitudinal side of the top of the pad, there is a right-angle structure or a structure without rounded corners. The right-angle edges constrain the lateral displacement of the foam material. When the right-angle structure is under pressure, the foam material is bidirectionally constrained at the edges, making it difficult for the foam material on that side to bulge outwards. Under the guidance of the asymmetrical rounded corner structure, the lateral bulging deformation of the polyurethane foam core material 1 occurs on the side where the rounded corner guide structure 4 is located, while no lateral bulging deformation occurs on the other side.

[0044] Through this asymmetrical contour design, deformation occurs on one side of the pre-designed rounded corner guide structure 4. One side of the rounded corner guide structure 4 can be arranged towards the open area or the reinforcing rib side inside the housing, while the other side is arranged towards the electronic components. During compression, the other side does not bulge or deform, and does not generate pressure interference or physical compression.

[0045] Preferably, the radius of the rounded corner of the rounded corner guide structure 4 is 1mm to 3.0mm.

[0046] When the cushioning foam pad is subjected to compression, the adhesive-free conductive area is located at the bottom of the pad and does not overlap with the double-sided adhesive layer. The conductive cloth 2 in this area is fully exposed. The current flows from the surface of the conductive cloth 2 at the top of the pad through the conductive cloth 2 on the side of the pad to the adhesive-free conductive area at the bottom of the pad, forming a purely physical conductive path.

[0047] When the height of the cushioning foam pad is compressed to 2.81mm, the impedance of the conductive path through the glue-free conductive area does not exceed 0.07 ohms. This compression height corresponds to the working compression state after the laptop's lower casing is assembled.

[0048] When the height of the cushioning foam pad is compressed to 4.46mm, the rounded corner guide structure 4 causes the polyurethane foam core material 1 to bulge and deform on the side where the rounded corner guide structure 4 is located, while there is no bulging deformation on the other side, and the rebound force of the cushioning foam pad does not exceed 1.6N.

[0049] In addition, a localized adhesive-free conductive area is set on one side of the bottom of the pad, forming a purely physical conductive path within this area. A single-sided rounded corner guide structure 4 is set on the opposite side of the top of the pad, guiding the pressure bulge to that side, preventing lateral bulging deformation on the side where the adhesive-free conductive area is located, thereby maintaining the flatness of the conductive contact surface on that side.

[0050] During the same compression stroke, the single-sided rounded corner guide structure 4 undertakes the deformation guidance function, while the local glue-free conductive area undertakes the current conduction function. The two are located in different areas of the pad and do not overlap in space. The rounded corner guide structure 4 maintains the stability of the structure on the side where the glue-free conductive area is located by constraining the deformation to its own side, thereby maintaining the contact reliability of the conductive path on that side. The local glue-free conductive area reduces the local stiffness of the bottom of the pad by reducing the coverage of the adhesive layer, so that the rounded corner guide structure 4 can play a deformation guidance role when under pressure.

[0051] The present invention will be further described below through specific embodiments.

[0052] This embodiment provides a high-conductivity buffer foam with controllable deformation direction, which includes a polyurethane foam core material 1, a conductive cloth 2, a partial double-sided adhesive layer 3, and a rounded corner guide structure 4.

[0053] Polyurethane foam core material 1 uses black B380F type polyurethane foam with a density of 48kg / m³. 3 After being cut to the predetermined size, it is ready for use.

[0054] The conductive cloth 2 is made of black PS-1394 copper-nickel plated conductive cloth, with polyester fiber fabric as the base material, a thickness of 0.06mm, and a planar resistivity of 0.05Ω / sq. The conductive cloth 2 is cut into sheets that fit the size of the polyurethane foam core material 1, and then bonded to the outer surface of the polyurethane foam core material 1 by hot pressing, so that the black copper-nickel conductive coating of the conductive cloth 2 faces outwards and the polyester fiber fabric base material faces the core material side, forming a cushioning foam pad after wrapping.

[0055] The partial double-sided adhesive layer 3 uses black 3M GTM715BP double-coated acrylic pressure-sensitive tape, which is applied to one end of the bottom of the cushioning foam pad, covering 60% of the total bottom width. The other end of the bottom of the pad does not have a double-sided adhesive layer, creating a non-adhesive conductive area. The 180-degree peel strength of the partial double-sided adhesive layer 3 is 1.6 N / mm.

[0056] A rounded corner guide structure 4 with a radius of 2.0 mm is provided on the longitudinal side of the top of the cushioning foam pad, which is the same as the partial double-sided adhesive layer 3; the other longitudinal side of the top of the cushioning foam pad maintains a right angle structure; the overall height of the cushioning foam pad is about 5 mm.

[0057] The prepared cushioning foam was tested under simulated installation. When compressed to a height of 2.81 mm, the impedance of the conductive path through the glue-free conductive area was 0.06 ohms. When compressed to a height of 4.46 mm, the lateral bulge only occurred on the side where the rounded corner guide structure 4 was located, and there was no bulging deformation on the other side. The rebound force was about 1.4 N.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-conductivity cushioning foam with controllable deformation direction, characterized in that, include: Polyurethane foam core material; Conductive cloth is wrapped around the outer surface of the polyurethane foam core material to form a cushioning foam pad. A partial double-sided adhesive layer is provided at one end of the bottom area of ​​the cushioning foam pad, while the other end of the bottom area of ​​the cushioning foam pad is an adhesive-free conductive area. A rounded corner guide structure is provided on the longitudinal side of the top of the cushioning foam pad, which is the same as the partial double-sided adhesive layer.

2. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, The rounded corner guide structure is located above the partial double-sided adhesive layer. When the cushioning foam pad is subjected to compressive force, the lateral bulging deformation of the polyurethane foam core material occurs on the side where the rounded corner guide structure is located.

3. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, The width of the partial double-sided adhesive layer covering one end of the bottom area accounts for 30% to 70% of the total bottom width.

4. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, The conductive cloth comprises an outer copper-nickel conductive coating and an inner polyester fiber fabric, and the thickness of the conductive cloth is 0.05mm to 0.08mm.

5. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, The planar resistance of the conductive cloth is less than 0.07 Ω / sq.

6. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, When the cushioning foam pad is compressed, the adhesive-free conductive area forms a purely physical conductive path from the top of the cushioning foam pad through the conductive cloth to the bottom of the cushioning foam pad, thereby avoiding the resistance interference of the local double-sided adhesive layer.

7. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, When the height of the cushioning foam pad is compressed to 2.81 mm, the impedance of the conductive path through the adhesive-free conductive area does not exceed 0.07 ohms.

8. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, When the height of the cushioning foam pad is compressed to 4.46mm, the rounded corner guide structure forces the polyurethane foam core material to bulge and deform only on the side where the rounded corner guide structure is located, and the rebound force of the cushioning foam pad does not exceed 1.6N.

9. The high-conductivity buffer foam with controllable deformation direction according to claim 1, characterized in that, The partial double-sided adhesive layer is an acrylic pressure-sensitive tape with a 180-degree peel strength greater than 1.45 N / mm.

10. The high-conductivity buffer foam with controllable deformation direction according to any one of claims 1 to 9, characterized in that, The cushioning foam is applied to the narrow space inside the lower casing of the laptop computer to provide conductive grounding and cushioning between the lower casing and the motherboard or electronic components.

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