Flexible circuit board with isolation shielding layer

Abstract

The utility model discloses a flexible circuit board with an isolation shielding layer, which comprises a board body. The plate body comprises an ultrathin hydrophobic protection layer, a dynamic hydrogen bond recovery layer, a first circuit copper foil layer, a gradient heat conduction insulation glue layer, a three-dimensional interlocking shielding layer, a liquid metal buffer layer, a second circuit copper foil layer, a vertical heat conduction array layer, a stress buffer layer, a graphene-silver nanometer shielding layer, a light response bonding layer and a piezoelectric sensing layer which are sequentially stacked from top to bottom. A photo-thermal response heat dissipation layer; and a multifunctional packaging layer. The three-dimensional interlocking shielding layer achieves ultrahigh electromagnetic shielding effectiveness through copper-graphene fiber weaving and ferrite filling, then the liquid metal buffer layer releases Ga-In-Sn alloy during crack propagation, a conductive path is repaired in real time, the recovery time is less than 0.1 second, and then the electromagnetic shielding effect is achieved. The dynamic hydrogen bond recovery layer passes through a dynamic covalent bond network of the polyurethane-urea elastomer, and the deformation recovery rate after bending is larger than 95%, so that the circuit board has the dynamic self-repairing capability.

Description

TECHNICAL FIELD

[0001] The utility model relates to circuit board technical field, concretely is a flexible circuit board with isolated shielding layer. BACKGROUND

[0002] Flexible circuit board is with polyimide or polyester film as base material makes a kind of highly reliable, excellent flexible printed circuit board, with the characteristics of high wiring density, light weight, thin thickness. Can be freely bent, winding, folding, can withstand millions of dynamic bending without damaging wire, can be arranged arbitrarily according to space layout requirements, and can be moved and stretched in three-dimensional space, so as to achieve the integration of component assembly and wire connection.

[0003] The existing flexible circuit board has the following problems:

[0004] 1. The traditional shielding layer adopts a planar conductive film, which is prone to delamination when bent, and the electromagnetic shielding effectiveness decreases;

[0005] 2. The homogeneous heat-conducting glue has thermal stress concentration, which leads to interface peeling;

[0006] 3. Lack of dynamic repair capability, the conductive path is prone to breakage after long-term bending. INVENTION CONTENTS

[0007] The utility model aims at providing a flexible circuit board with an isolated shielding layer to solve the problems raised in the background art.

[0008] To achieve the above-mentioned purpose, the utility model provides the following technical scheme: a flexible circuit board with an isolated shielding layer, comprising a board body, the board body comprises an ultrathin hydrophobic protective layer, a dynamic hydrogen bond recovery layer, a first circuit copper foil layer, a gradient heat-conducting insulating adhesive layer, a three-dimensional interlocking shielding layer, a liquid metal buffer layer, a second circuit copper foil layer, a vertical heat-conducting array layer, a stress buffer layer, a graphene-silver nano shielding layer, a light-responsive adhesive layer, a piezoelectric sensing layer, a photo-thermal response heat dissipation layer and a multifunctional packaging layer stacked in order from top to bottom.

[0009] The three-dimensional interlocking shielding layer is formed by weaving copper-graphene composite conductive fibers into a three-dimensional network structure, and the voids are filled with ferrite nanoparticles.

[0010] The vertical heat-conducting array layer comprises micro-holes formed by laser drilling and chemical copper plating columns, the micro-holes have a diameter of 30 μm and an aspect ratio of 10:1.

[0011] The liquid metal buffer layer is composed of Ga-In-Sn alloy microcapsules embedded in a silica gel matrix, and the microcapsules have a diameter of 50 μm.

[0012] The gradient heat-conducting insulating adhesive layer is a graphene and aluminum nitride nanosheet composite adhesive, and the content of the bottom filler is 50wt%, and the content of the top is 10wt%, the ultrathin hydrophobic protective layer is fluorinated polyimide, the thickness is 0.01mm, and the hydrophobic angle is greater than or equal to 150°.

[0013] The piezoelectric sensing layer is a PVDF-TrFE film, and the photo-thermal response heat dissipation layer comprises a carbon nanotube / phase change paraffin composite coating, and the phase change temperature is 45 DEG C.

[0014] The light response adhesive layer is a photosensitive polyimide containing azobenzene, and the adhesive strength is regulated by 365nm and 405nm ultraviolet light.

[0015] Compared with the prior art, the utility model has the advantages of:

[0016] The three-dimensional interlocking shielding layer is woven by copper-graphene fiber and filled with ferrite, so that the super-high electromagnetic shielding efficiency is realized, secondly, the liquid metal buffer layer releases Ga-In-Sn alloy (melting point 15 DEG C) when the crack expands, and the conductive path is repaired in real time, and the recovery time is less than 0.1 second, then, the dynamic hydrogen bond recovery layer is restored by the dynamic covalent bond network of polyurethane-urea elastomer, and the deformation recovery rate after bending is greater than 95%, so that the circuit board has the dynamic self-repairing ability, finally, the copper column of the vertical heat conduction array layer has a depth-width ratio of 10:1, the vertical heat conduction coefficient is greater than 400W / mK, the thermal resistance is reduced by 70%, the photo-thermal response heat dissipation layer triggers the phase change endothermic (endothermic amount 200J / g) at 45 DEG C, and the heat dissipation efficiency is enhanced by carbon nanotube infrared radiation, so that the gradient heat dissipation and heat management are realized. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 It is a schematic view of the utility model;

[0018] Fig. 2 It is a sectional view of the utility model.

[0019] In the drawing: 1, board body; 2, ultrathin hydrophobic protective layer; 3, dynamic hydrogen bond recovery layer; 4, first circuit copper foil layer; 5, gradient heat-conducting insulating adhesive layer; 6, three-dimensional interlocking shielding layer; 7, liquid metal buffer layer; 8, second circuit copper foil layer; 9, vertical heat conduction array layer; 10, stress buffer layer; 11, graphene-silver nanometer shielding layer; 12, light response adhesive layer; 13, piezoelectric sensing layer; 14, photo-thermal response heat dissipation layer; 15, multifunctional packaging layer. DETAILED DESCRIPTION

[0020] Clearly and completely describe the technical scheme in the embodiments of the utility model with reference to the drawings in the embodiments of the utility model, obviously, the described embodiments are only a part of the embodiments of the utility model, and not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the ordinary skill in the art without creative labor belong to the scope of the utility model protection.

[0021] Please refer to Figs. 1-2 The utility model provides a kind of technical scheme: a flexible circuit board with isolation shielding layer, including board body 1, board body 1 includes from top to bottom sequentially stacked ultra-thin hydrophobic protective layer 2, dynamic hydrogen bond recovery layer 3, first circuit copper foil layer 4, gradient heat conduction insulating adhesive layer 5, three-dimensional interlocking shielding layer 6, liquid metal buffer layer 7, second circuit copper foil layer 8, vertical heat conduction array layer 9, stress buffer layer 10, graphene-silver nano shielding layer 11, light response adhesive layer 12, piezoelectric sensing layer 13, photo-thermal response heat dissipation layer 14 and multi-functional packaging layer 15.

[0022] Three-dimensional interlocking shielding layer 6 is woven into three-dimensional network structure by copper-graphene composite conductive fiber, and the void is filled with ferrite nanoparticles.

[0023] Vertical heat conduction array layer 9 contains micro-holes formed by laser drilling and chemical copper plating columns, and the micro-holes have a diameter of 30 μm and an aspect ratio of 10:1.

[0024] Liquid metal buffer layer 7 is composed of Ga-In-Sn alloy microcapsules embedded in silica gel matrix, and the microcapsules have a diameter of 50 μm.

[0025] Gradient heat conduction insulating adhesive layer 5 is a graphene and aluminum nitride nanosheet composite adhesive, and the filler content at the bottom is 50 wt%, and the top is 10 wt%, ultra-thin hydrophobic protective layer 2 is fluorinated polyimide, with a thickness of 0.01 mm, and a hydrophobic angle ≥ 150°.

[0026] Piezoelectric sensing layer 13 is a PVDF-TrFE film, and photo-thermal response heat dissipation layer 14 contains a carbon nanotube / phase change paraffin composite coating, with a phase change temperature of 45℃.

[0027] Light response adhesive layer 12 is a photosensitive polyimide containing azobenzene, and the adhesive strength is regulated by 365 nm and 405 nm ultraviolet light.

[0028] 101. Ultra-thin hydrophobic protective layer 2 and dynamic hydrogen bond recovery layer 3

[0029] Connection method: photo-cured fluorinated polyimide is chemically bonded to the surface of dynamic hydrogen bond recovery layer through coupling agent (KH-550).

[0030] Process details:

[0031] Silane coupling agent (10 nm thick) is coated on the surface of the dynamic hydrogen bond recovery layer, and is baked at 80°C for 10 minutes;

[0032] The fluorinated polyimide solution (15% solid content) is spin-coated, and is ultraviolet cured (385 nm, 50 mJ / cm²) to form a covalent bond connection.

[0033] Effect: Prevent delamination, enhance interface bonding strength (peeling force > 5 N / cm).

[0034] Dynamic hydrogen bond recovery layer 3 first circuit copper foil layer 4

[0035] Connection method: hot pressure sensitive conductive adhesive (Ag epoxy resin) bonding.

[0036] Process details:

[0037] Silver epoxy glue (5 μm thick) is printed on the surface of the copper foil, and the glue contains 1 wt% carbon nanotube reinforced thermal conductivity;

[0038] Hot pressing conditions: 120°C, 0.5 MPa pressure, holding for 5 minutes, forming a physical-chemical mixed bond.

[0039] Effect: Conductive glue provides electrical connection and mechanical anchoring, and carbon nanotubes improve in-plane thermal conductivity.

[0040] 103. First circuit copper foil layer 4 gradient thermal conductive insulation glue layer 5

[0041] Connection method: Gradient glue layer is directly coated and cured, without additional adhesive.

[0042] Process details:

[0043] The copper foil surface microgroove (see layer 4 design) is embedded in the gradient glue bottom high thermal conductivity area (50 wt% AlN);

[0044] Double screw co-extrusion process realizes gradient distribution, and is heat cured (160°C, 30 minutes) to form an interpenetrating network.

[0045] Effect: Mechanical interlocking + chemical crosslinking, thermal resistance reduction of 40%.

[0046] 104. Gradient thermal conductive insulation glue layer 5 and three-dimensional interlocking shielding layer 6

[0047] Connection method: Ferrite filling slurry permeation curing.

[0048] Process details:

[0049] Ferrite slurry (NiZnFe2O4, particle size 50 nm) is coated on the top of the gradient glue layer (flexible side);

[0050] Three-dimensional braided copper-graphene fiber network is impregnated with slurry, then vacuum-assisted filling of voids, and cured at 120℃.

[0051] Effect: Mechanical interlocking after slurry curing, shielding layer and adhesive layer shear strength > 8MPa.

[0052] Three-dimensional interlocking shielding layer 6 Liquid metal buffer layer 7

[0053] Connection method: Silicone matrix wraps the end of the shielding layer fiber.

[0054] Process details:

[0055] The upper and lower surfaces of the shielding layer are coated with liquid silicone (containing microcapsules), with a thickness of 0.1mm;

[0056] The silicone forms a "barb" structure between the fibers of the shielding layer, and is physically anchored after curing.

[0057] Effect: Avoids interlayer slip, while allowing microcapsule rupture to release liquid metal during bending.

[0058] 106. Liquid metal buffer layer 7 and second circuit copper foil layer 8

[0059] Connection method: Laser-induced local welding.

[0060] Process details:

[0061] Copper foil back pre-Sn-Bi low-temperature solder (melting point 138℃);

[0062] Local heating with pulsed laser (1064nm, pulse width 10ns), solder melts and combines with silicone matrix.

[0063] Effect: Selective welding point spacing 200μm, with both conductivity and flexibility.

[0064] 107. Second circuit copper foil layer 8 and vertical heat conduction array layer 9

[0065] Connection method: Direct growth connection of electroless copper pillars.

[0066] Process details:

[0067] After laser drilling of the copper foil surface, electroless copper plating solution (containing CuSO4, H2SO4) fills the micropores;

[0068] The electroplated copper pillars form a metallurgical bond with the upper and lower copper foils, with an interface resistance <0.01Ω.

[0069] Effect: Seamless connection of vertical heat conduction paths, with matching thermal expansion coefficients (CTE 17ppm / ℃).

[0070] 108. Vertical heat conduction array layer 9 and stress buffer layer 10

[0071] Connection: PDMS prepolymer in-situ foaming bonding.

[0072] Process details:

[0073] Aerogel-PDMS prepolymer is injected into the surface of the heat-conducting array layer, and the foaming agent (NaHCO3) generates CO2 to form a porous structure.

[0074] Curing at 60°C for 2 hours, PDMS forms a siloxane bond (Si-O-Cu) with the surface of the copper column.

[0075] Effect: The porous structure absorbs 90% of the impact energy, and the interfacial bonding strength is > 3MPa.

[0076] 109. Stress buffer layer 10 and graphene-silver nanometer shielding layer 11

[0077] Connection: Direct growth of silver nanowires by magnetron sputtering.

[0078] Process details:

[0079] CVD growth of single-layer graphene on the surface of PDMS (methane, 1000°C);

[0080] Magnetron sputtering of silver target (power 200W, Ar gas atmosphere), silver nanowires (diameter 20nm) self-assemble into a network.

[0081] Effect: Silver nanowires are embedded in the surface of PDMS, sheet resistance <0.1Ω / sq, light transmittance 82%.

[0082] 110. Graphene-silver nanometer shielding layer 11 and light-responsive bonding layer 12

[0083] Connection: UV light regulated covalent bonding.

[0084] Process details:

[0085] Azo-containing photosensitive polyimide is coated on the surface of the shielding layer (thickness 2μm);

[0086] Selective UV exposure (365nm debonding area, 405nm curing area) through a mask, forming a reversible bonding interface.

[0087] Effect: Local bonding strength is adjustable (0.5~5MPa), supporting modular maintenance.

[0088] 111. Light-responsive bonding layer 12 and piezoelectric sensing layer 13

[0089] Connection: Conductive silver paste printing + thermal pressure bonding.

[0090] Process details:

[0091] PVDF-TrFE film back printed silver paste conductor (line width 50 μm);

[0092] Thermal compression (100℃, 0.2MPa) makes silver paste conductive with photoresponsive layer, and simultaneously adheres and fixes.

[0093] Effect: signal transmission resistance <1Ω, bending resistance >100000 times.

[0094] 112. Piezoelectric sensing layer 13 and photo-thermal response heat dissipation layer 14

[0095] Connection method: phase change paraffin hot melt adhesion.

[0096] Process details:

[0097] Carbon nanotube / paraffin composite (phase change temperature 45℃) is coated on the surface of the piezoelectric layer;

[0098] Heating to 50℃ makes paraffin melt, and physical adhesion is formed after cooling (thickness 0.05mm).

[0099] Effect: interface thermal resistance <0.5K·cm² / W, repeatable thermal cycle >1000 times.

[0100] Photo-thermal response heat dissipation layer 14 and multifunctional packaging layer 15

[0101] Connection method: TiO2 catalytic self-repairing polysiloxane crosslinking.

[0102] Process details:

[0103] After coating the packaging layer prepolymer (containing 5wt% TiO2 nanoparticles), ultraviolet light (365nm) is used to initiate crosslinking;

[0104] TiO2 generates free radicals at the scratch site through photocatalysis, promoting polysiloxane chain recombination.

[0105] Effect: self-repairing rate >95% (48 hours, room temperature) when scratch depth <50μm.

[0106] It should be noted that the relational terms such as first and second and the like are used merely to differentiate one entity or action from another entity or action, without necessarily requiring or implying that there is any such actual relationship or order between them. In addition, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or equipment including a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or equipment.

[0107] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flexible wiring board with an isolation shield layer, comprising a board body (1), characterized in that: The plate body (1) comprises, from top to bottom, a super-thin hydrophobic protective layer (2), a dynamic hydrogen bond recovery layer (3), a first circuit copper foil layer (4), a gradient heat-conducting insulation adhesive layer (5), a three-dimensional interlocking shielding layer (6), a liquid metal buffer layer (7), a second circuit copper foil layer (8), a vertical heat-conducting array layer (9), a stress buffer layer (10), a graphene-silver nano shielding layer (11), a light-responsive adhesive layer (12), a piezoelectric sensing layer (13), a photo-thermal response heat dissipation layer (14), and a multifunctional packaging layer (15).

2. The flexible wiring board with an isolation shielding layer according to claim 1, wherein: The three-dimensional interlocking shielding layer (6) is formed by copper-graphene composite conductive fibers into a three-dimensional network structure, and the voids are filled with ferrite nanoparticles.

3. The flexible wiring board with an isolation shielding layer according to claim 1, wherein: The vertical heat-conducting array layer (9) comprises micro-holes formed by laser drilling and chemical copper plating columns.

4. The flexible wiring board with an isolation shielding layer according to claim 1, wherein: The liquid metal buffer layer (7) is composed of Ga-In-Sn alloy microcapsules embedded in a silica gel matrix.

5. The flexible wiring board with an isolation shielding layer according to claim 1, wherein: The gradient heat-conducting insulation adhesive layer (5) is a graphene and aluminum nitride nanosheet composite adhesive, and the bottom filler content is 50wt%, and the top is 10wt%, the super-thin hydrophobic protective layer (2) is fluorinated polyimide, and the thickness is 0.01mm.

6. The flexible wiring board with an isolation shielding layer according to claim 1, wherein: The piezoelectric sensing layer (13) is a PVDF-TrFE film, and the photo-thermal response heat dissipation layer (14) comprises a carbon nanotube / phase change paraffin composite coating.

7. The flexible wiring board with an isolation shielding layer according to claim 1, wherein: The light-responsive adhesive layer (12) is a photosensitive polyimide containing azobenzene.

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