Composite metal foil and cable

Abstract

The invention relates to the technical field of cables, in particular to a composite metal foil and a cable. The composite metal foil is used for cable shielding and comprises a supporting layer and a shielding layer which are arranged in a stacked mode, and the dyne value of the surface, away from the shielding layer, of the supporting layer is 54-58. According to the composite metal foil, when the dyne value of the surface, away from the shielding layer, of the supporting layer in the composite metal foil is 54-58, the affinity of the supporting layer and tin liquid is improved when the composite metal foil is tinned, the contact difficulty of the tin liquid and the supporting layer can be reduced, the tinning speed on the supporting layer is increased, and therefore the tinning effect is improved, and the tinning effect is improved. And meanwhile, the composite metal foil has relatively strong electromagnetic shielding performance.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a composite metal foil and a cable. Background Art

[0002] Wires and cables are the medium for energy and information transmission, and play a vital role in the development of the economy and society. In recent years, with the development of the information age, cables used to transmit information and data signals support the communication needs of modern society. In order to reduce external electromagnetic interference and achieve accurate and stable signal transmission, a shielding layer is generally added to the cable. At present, metal braided layers, metal foil layers, combined shielding layers or semiconductor layers are generally selected as shielding layers according to the application scenario. In order to improve the performance of the shielding layer, the shielding layer is usually compounded with high-performance thermoplastic engineering plastics. Among them, composite copper foil is widely used in the electronics industry because it has both excellent mechanical properties of polymers and excellent conductivity of metal materials. However, when welding composite copper foil, the substrate needs to be melted for welding. Thinner composite materials can be melted quickly, but the elongation of the shielding layer will decrease, causing the shielding layer to break when the cable is wound, and the shielding effect will fail. If a thicker substrate is used to form a composite copper foil, the overall elongation can be guaranteed, but it is not easy to melt when making the joint, resulting in high difficulty in tinning and poor welding effect. Therefore, the application of composite copper foil in cable shielding materials is hindered. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect of poor tin effect on the surface of the composite metal foil in the prior art, thereby providing a composite metal foil and a cable.

[0004] Another technical problem to be solved by the present invention is to overcome the defect of poor elongation of the composite metal foil in the prior art, thereby providing a composite metal foil and a cable.

[0005] The present invention provides a composite metal foil for cable shielding, comprising a support layer and a shielding layer which are stacked, wherein the dyne value of the support layer away from the shielding layer is 54-58.

[0006] In the present invention, when the dyne value of a surface of the support layer in the composite metal foil away from the shielding layer is 54 to 58, the affinity of the support layer and the tin liquid is improved when the composite metal foil is tinned, the contact difficulty between the tin liquid and the support layer can be reduced, and the tinning rate on the support layer is increased, thereby improving the tinning effect, and the composite metal foil has a strong electromagnetic shielding performance. Exemplarily, the dyne value of a surface of the support layer away from the shielding layer is 54, 55, 56, 57, 58 or an interval consisting of any two values.

[0007] Specifically, in the present invention, the surface of the support layer of the composite metal foil is treated by chemical treatment or physical treatment, such as immersion in an acid solution, immersion in an alkaline solution, plasma treatment, corona treatment, etc.

[0008] In some of the embodiments, the specific steps of the chemical treatment method are: soaking the support layer in an alkaline solution for 20s-40s. During the soaking of the support layer in the alkaline solution, the hydroxide ions in the alkaline solution attack the ester bond of ethylene glycol in the support layer, react with the ester bond by hydrolysis, break the surface molecular chain, and change the surface of the material from polyester to sodium polyethylene terephthalate and ethylene glycol. The surface becomes soft and expands slightly. On the one hand, the surface strength of the support layer is reduced, so that the alloy layer can better enter the interior of the support layer during sputtering, improve the bonding degree between the sputtering layer and the support layer, and increase the peeling strength between the metal layer and the support layer after copper plating. After the surface of the support layer is damaged, the support layer can be dissolved faster in the tin liquid when welding the cable joint, thereby improving the tinning effect of the shielding layer. On the other hand, the dyne value of the support layer is increased by soaking in the alkaline solution, and the affinity between the support layer and the tin liquid during tinning is enhanced. During welding, the tin liquid can be helped to contact the support layer more fully to melt the support layer, thereby improving the tinning rate and improving the reliability of the composite metal foil during joint welding.

[0009] In some embodiments, when the support layer is chemically treated, the concentration of the alkaline substance in the alkaline solution is 5 wt % to 10 wt %. Exemplarily, the alkaline substance is at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide and barium hydroxide.

[0010] The concentration of the alkaline substance in the alkaline solution should not be too high, otherwise the support layer will be damaged too much, which will reduce the elongation at break after copper plating. If the concentration is too low, the treatment effect will be poor. For example, the concentration of the alkaline substance in the alkaline solution is 5wt%, 6wt%, 8wt% and 10wt% or an interval consisting of any two values. At the same time, in order to improve the efficiency of the chemical treatment, when the concentration of the alkaline substance in the alkaline solution is low, in the chemical treatment process, adding an ultrasonic treatment step can speed up the reaction speed and improve the uniformity of the surface treatment, thereby improving the tinning effect of the composite metal foil and improving the elongation of the composite metal foil.

[0011] In one embodiment, the support layer is treated on both sides simultaneously with an alkaline solution to modify the two surfaces of the support layer, which can not only improve the bonding strength between the support layer and the shielding layer, but also improve the elongation and tinning efficiency of the composite metal foil, further improve the processing efficiency, and have strong operability. Only the surface material is processed, and sodium hydroxide will not attack the inside of the material.

[0012] Taking sodium hydroxide as an alkaline substance of an alkaline solution as an example, and polyethylene terephthalate as a main material of the support layer, the reaction equation of sodium hydroxide and polyethylene terephthalate is shown in formula (I).

[0013]

[0014] The value of n in formula (I) ranges from 50 to 200, preferably from 50 to 100.

[0015] In some of the embodiments, the specific steps of the physical treatment method are to use high frequency and high voltage to perform corona discharge on the surface of the support layer away from the shielding layer, and use the generated low-temperature plasma to produce free radical reaction on the surface of the support layer to cross-link the polymer in the support layer, so that the surface of the support layer forms a rough granular state, and at the same time enhances the wettability of the surface of the support layer to polar solvents. The generated ions enter the support layer under the action of electric shock and penetration to destroy the molecular structure of the support layer, oxidize and polarize the treated surface molecules, and thus modify the surface material of the support layer.

[0016] In order to further improve the modification effect of the support layer, enhance the cross-linking reaction of the polymer in the support layer, and improve the tinning effect of the composite metal foil, the voltage is 5000-15000V / m when the support layer is subjected to corona discharge. 2 . Exemplarily, the voltage is 5000V / m 2 、6500V / m 2 、7000V / m 2 、7500V / m 2 、8000V / m 2 、12000V / m 2 、13500V / m 2 、15000V / m 2 Or any interval between two values.

[0017] In some of the embodiments, different powers are used to treat the two sides of the support layer separately. The copper-plated side is electroplated with a lower power to achieve a dyne value of 44 to 50, and the support layer is treated before electroplating to enhance the bonding strength between the sputtered metal layer and the support layer. After the copper is plated, the non-plated surface is treated with a higher power corona or plasma to achieve a surface dyne value of more than 54 to enhance the surface energy, increase the wettability with the tin liquid, and help dissolve the support layer for soldering.

[0018] Specific reference Figure 1As shown, in order to further enhance the peeling strength between the shielding layer and the supporting layer, a transition layer is provided between the supporting layer and the shielding layer. More specifically, the transition layer is a metal layer formed on the supporting layer by vacuum sputtering, evaporation plating, spraying, chemical plating, etc. The present invention makes the supporting layer conductive through the metal layer, and subsequently forms the shielding layer by electroplating, thereby enhancing the peeling strength between the shielding layer and the supporting layer and improving the shielding effectiveness.

[0019] The maximum depth of the transition layer into the support layer is 0.01 to 0.1 μm. Figure 2 , Figure 2 H in the figure is the distance between the plane where the farthest point of the transition layer is located away from the support layer and the lowest point of the side of the support layer facing the transition layer, indicating the maximum depth of the transition layer into the support layer. Exemplarily, the maximum depth of the transition layer into the support layer is 0.01μm, 0.02μm, 0.04μm, 0.07μm, 0.9μm and 0.1μm or an interval consisting of any two values. The present invention limits the maximum depth of the transition layer into the support layer to 0.01 to 0.1μm, which can not only enhance the peeling strength between the shielding layer and the support layer, but also accelerate the dissolution rate of the support layer in the tin liquid after the support layer is destroyed, and the tinning effect is better. Furthermore, the composite metal foil provided in the embodiment of the present invention has a strong electromagnetic shielding performance.

[0020] Specifically, the maximum depth of the transition layer into the supporting layer refers to the maximum value of the depth of the transition layer into the supporting layer. In some embodiments, the depth of the transition layer into the supporting layer can be measured by sectioning using a scanning electron microscope, an optical electron microscope or a focused ion beam, or other measurement methods can be used. The present invention is not limited to this, as long as the depth of the transition layer into the supporting layer can be accurately measured and the maximum depth can be obtained.

[0021] In some embodiments, the components of the transition layer include conductive metal, polyethylene terephthalate, sodium terephthalate and ethylene glycol, and the material of the conductive metal is the same as at least one of the materials of the shielding layer. Specifically, if the material of the shielding layer includes copper and aluminum, the conductive metal can be copper, aluminum, or a mixture of copper and aluminum.

[0022] In order to improve the bonding strength between the supporting layer and the shielding layer, in the transition layer, the content of polyethylene terephthalate is 2wt% to 30wt%, the content of sodium terephthalate is 2wt% to 15wt%, and the content of ethylene glycol is 5wt% to 25wt%. Exemplarily, the content of polyethylene terephthalate in the transition layer is 2wt%, 5wt%, 10wt%, 12wt%, 20wt%, 25wt%, 30wt% or an interval consisting of any two values, the content of sodium terephthalate is 2wt%, 5wt%, 10wt%, 12wt%, 13wt%, 15wt% or an interval consisting of any two values, and the content of ethylene glycol is 5wt%, 8wt%, 15wt%, 20wt%, 25wt% or an interval consisting of any two values.

[0023] In order to improve the elongation and tinning effect of the composite metal foil, the side of the support layer facing away from the shielding layer has a mixed layer, and the mixed layer includes polyethylene terephthalate, sodium terephthalate and ethylene glycol.

[0024] Optionally, the mixing layer and the transition layer may be arranged in layers or in a fusion arrangement.

[0025] In order to further improve the elongation of the composite metal foil, the content of the polyethylene terephthalate in the mixed layer is 50wt% to 70wt%. For example, the content of the polyethylene terephthalate in the mixed layer is 50wt%, 57wt%, 58wt%, 59wt%, 60wt%, 68wt%, 70wt% or an interval consisting of any two values. At the same time, in order to enhance the tinning effect of the composite metal foil, the content of the sodium terephthalate in the mixed layer is 15wt% to 25wt%. For example, , the content of sodium terephthalate in the mixed layer accounts for 15wt%, 16wt%, 19wt%, 20wt%, 22wt%, 25wt% or a range consisting of any two values. In order to further improve the elongation and tinning effect of the composite metal foil, the content of ethylene glycol in the mixed layer accounts for 15wt% to 25wt%. Exemplarily, the content of ethylene glycol in the mixed layer accounts for 15wt%, 16wt%, 17wt%, 20wt%, 23wt% and 25wt% or a range consisting of any two values.

[0026] In order to improve the elongation of the composite metal foil, the support layer provided by the present invention includes at least one of polyethylene terephthalate, polyimide, polyethylene terephthalate copolymer, polyethylene naphthalate, polyethylene terephthalate (PET), polypropylene (PP), polyimide (PI), polyvinyl chloride (PVC), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), and polycarbonate (PC); specifically, the support layer is preferably polyethylene terephthalate, which has good gloss, high strength, wear resistance, chemical corrosion resistance and dimensional stability, especially PET has good elongation and tensile strength, and is more suitable for use as a support layer of the composite metal foil. More preferably, by combining polyethylene terephthalate with polyethylene terephthalate Materials such as ethylene glycol copolymer, neopentyl glycol (NPG) copolymer and polyethylene naphthalate are blended to make films. Adding other ingredients in appropriate amounts can reduce the melting point of the PET film, improve the hardness of the material, increase the tensile strength, and be more conducive to improving the performance of the composite metal foil. More specifically, by copolymerizing polyethylene terephthalate and neopentyl glycol, polyethylene terephthalate is modified by neopentyl glycol to synthesize a series of copolyesters with different glycol ratios. The melting point and crystallinity of the obtained copolyester are inversely proportional to the amount of neopentyl glycol added. At the same time, the impact resistance and processing performance of the formed copolyester are greatly improved. Among them, when the molar fraction of neopentyl glycol is 2% to 15% of that of polyethylene terephthalate, the impact resistance and processing performance of the copolyester formed by copolymerization are better.

[0027] In some embodiments, the thickness of the support layer is 3-10 μm. Exemplarily, the thickness of the support layer is 3 μm, 5 μm, 8 μm and 10 μm or an interval consisting of any two values.

[0028] In some embodiments, the shielding layer includes at least one of copper, aluminum, gold, silver, iron, nickel, chromium, and zinc.

[0029] The thickness of the shielding layer is 0.5-5 μm. Exemplarily, the thickness of the shielding layer is 0.5 μm, 1 μm, 3 μm and 5 μm or an interval consisting of any two values.

[0030] An adhesive layer is further provided between the shielding layer and the substrate, and the thickness of the adhesive layer is 0.1-2 μm. Exemplarily, the thickness of the adhesive layer is 0.1 μm, 0.5 μm, 0.8 μm, 1.2 μm and 2 μm or an interval consisting of any two values.

[0031] Preferably, the adhesive layer includes at least one of resins selected from the group consisting of vinyl acetate, polyester, polyethylene, polyamide, rubber, acrylate, phenolic, epoxy, polyimide, urethane, melamine, alkyd, ABF and the like.

[0032] At the same time, the present invention also provides a cable, comprising the above-mentioned composite metal foil, and the cable has high elongation, good tinning effect and strong shielding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 is a schematic diagram of the structure of the composite metal foil provided in Example 1 of the present invention;

[0035] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0036] Figure 3 is a schematic diagram of the structure of the composite metal foil provided in Example 5 of the present invention;

[0037] Figure 4 is a schematic diagram of the structure of the composite metal foil provided in Example 6 of the present invention;

[0038] Reference numerals:

[0039] 1-shielding layer; 2-transition layer; 3-support layer; 4-mixing layer. DETAILED DESCRIPTION

[0040] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0041] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0042] Example 1

[0043] This embodiment provides a composite metal foil, the structure of which is shown in FIG. Figure 1, including a supporting layer 3 and a shielding layer 1 stacked in layers, a transition layer 2 is provided between the supporting layer and the shielding layer, the supporting layer is made of polyethylene terephthalate with a thickness of 5 μm, the shielding layer is made of copper foil with a thickness of 2 μm, the transition layer is made of copper, and the dyne value of the supporting layer away from the surface of the shielding layer is 54.

[0044] Example 2

[0045] This embodiment provides a composite metal foil. The composite metal foil structure, the material and the thickness of each structure are the same as those in Embodiment 1, except that the dyne value of the surface of the support layer away from the shielding layer is 58.

[0046] Example 3

[0047] See also Figure 1 and Figure 2 This embodiment provides a composite metal foil, the composite metal foil structure, the material and thickness of each structure are the same as those in Embodiment 1, except that the maximum depth of the transition layer into the support layer is 0.01 μm, wherein: Figure 2 H in the middle represents the maximum depth of the transition layer into the supporting layer.

[0048] Example 4

[0049] See also Figure 1 and Figure 2 This embodiment provides a composite metal foil, the composite metal foil structure, the material and thickness of each structure are the same as those in Embodiment 1, except that the maximum depth of the transition layer into the support layer is 0.1 μm, wherein, Figure 2 H in the middle represents the maximum depth of the transition layer into the supporting layer.

[0050] Example 5

[0051] This embodiment provides a composite metal foil, the structure of which is shown in FIG. Figure 3 ,include,

[0052] The support layer 3 and the shielding layer 1 are stacked.

[0053] A transition layer 2 is provided between the support layer and the shielding layer.

[0054] A mixed layer 4 is provided on the side of the support layer facing away from the shielding layer.

[0055] The support layer is made of polyethylene terephthalate and has a thickness of 3 μm.

[0056] The shielding layer is made of copper foil with a thickness of 1.2μm.

[0057] The transition layer is made of copper.

[0058] The mixed layer material includes polyethylene terephthalate, sodium terephthalate and ethylene glycol.

[0059] The support layer is immersed in a 5wt% sodium hydroxide solution for 20s, and the dyne value of the surface of the support layer away from the shielding layer is 56.

[0060] The mixed layer contains 50 wt % polyethylene terephthalate, 15 wt % sodium terephthalate and 20 wt % ethylene glycol, and the rest are inevitable impurities.

[0061] Example 6

[0062] This embodiment provides a composite metal foil, the structure of which is shown in FIG. Figure 4 ,include,

[0063] The support layer 3 and the shielding layer 1 are stacked.

[0064] A transition layer 2 is provided between the support layer and the shielding layer.

[0065] The mixed layer 4 is disposed on two opposite sides of the support layer.

[0066] The support layer is made of polyethylene terephthalate and has a thickness of 3 μm.

[0067] The shielding layer is made of copper foil with a thickness of 1.2μm.

[0068] The transition layer is made of copper.

[0069] The mixed layer material includes polyethylene terephthalate, sodium terephthalate and ethylene glycol.

[0070] The support layer is immersed in a 5wt% sodium hydroxide solution for 20s, and the dyne value of the surface of the support layer away from the shielding layer is 56.

[0071] The content of polyethylene terephthalate in the mixed layer accounts for 55 wt %, the content of sodium terephthalate accounts for 18 wt % and the content of ethylene glycol accounts for 25 wt %, and the rest are inevitable impurities.

[0072] Comparative Example 1

[0073] This comparative example provides a composite metal foil, and the composite metal foil structure, the material and the thickness of each structure are the same as those of Example 1, except that the dyne value of the surface of the support layer away from the shielding layer is 52.

[0074] Comparative Example 2

[0075] This comparative example provides a composite metal foil, and the composite metal foil structure, the material and the thickness of each structure are the same as those of Example 1, except that the dyne value of the surface of the support layer away from the shielding layer is 60.

[0076] Experimental example

[0077] The elongation and tin-coated area ratio of the composite metal foil provided in Examples 1-6 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0078] Among them, the elongation of the composite metal foil is tested by a tensile machine.

[0079] A tinning test was carried out using a 50×50 mm composite metal foil sample at 270°C for 3 seconds, and the tinning area ratio of the metal foil was calculated using imageJ image processing software or MATLAB image processing program, where tinning area ratio (%) = tinning area / composite metal foil surface area × 100.

[0080] Table 1 Properties of composite metal foil

[0081]

[0082]

[0083] According to the data in Table 1, the composite metal foil provided by the present invention has good elongation and tinning effect, which can ensure the connection stability between the composite metal foil and the joint during cable manufacturing, and on the basis of ensuring the electromagnetic shielding performance, meet the elongation requirements, reduce the probability of breakage, and improve the working reliability of the cable.

[0084] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A composite metal foil for electromagnetic shielding in cables, characterized in that: The invention comprises a supporting layer and a shielding layer which are stacked, wherein the dyne value of the surface of the supporting layer away from the shielding layer is 54-58.

2. The composite metal foil according to claim 1, characterized in that A transition layer is provided between the support layer and the shielding layer, and the maximum depth of the transition layer penetrating into the support layer is 0.01-0.1 μm.

3. The composite metal foil according to claim 2, characterized in that: The transition layer comprises conductive metal, polyethylene terephthalate, sodium terephthalate and ethylene glycol, and the material of the conductive metal is the same as at least one of the materials of the shielding layer.

4. The composite metal foil according to claim 1, characterized in that: A mixed layer is provided on a side of the support layer facing away from the shielding layer. The mixed layer comprises polyethylene terephthalate, sodium terephthalate and ethylene glycol.

5. The composite metal foil according to claim 4, characterized in that: In the mixed layer, the content of the polyethylene terephthalate is 50wt% to 70wt%, and / or, The content of sodium terephthalate is 15wt% to 25wt%; and / or, The content of ethylene glycol is 15wt% to 25wt%.

6. The composite metal foil according to claim 5, characterized in that: The mixed layer is provided on two opposite sides of the support layer.

7. The composite metal foil according to any one of claims 1 to 6, characterized in that: The support layer includes at least one of polyethylene terephthalate, polyimide, polyethylene terephthalate copolymer, polyethylene naphthalate, and / or, The thickness of the support layer is 3-10 μm.

8. The composite metal foil according to claim 7, characterized in that: The shielding layer includes at least one of copper foil, aluminum foil, and metal braided layer, and / or, The thickness of the shielding layer is 0.5-5 μm.

9. The composite metal foil according to claim 1, characterized in that: An adhesive layer is also provided between the shielding layer and the supporting layer, and the thickness of the adhesive layer is 0.1-2 μm.

10. A cable, characterized in that: The composite metal foil comprises the composite metal foil as described in any one of claims 1 to 9.

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