Composite metal foil, metal-clad laminated plate, chip and circuit board

Abstract

The invention discloses a composite metal foil, a metal-clad laminated plate, a chip and a circuit board. The composite metal foil comprises a substrate layer and a functional layer which are laminated, and the heat conductivity coefficient of the substrate layer is greater than 400W / m.K. According to the composite metal foil, the metal-clad laminate, the chip and the circuit board provided by the invention, the compactness of the functional layer is improved, the toughness of the composite metal foil is improved, and the functional layer is prevented from cracking in the circuit board pressing process.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of electromagnetic shielding, and in particular to an electromagnetic shielding cover and a circuit board. Background Art

[0002] Currently, mobile terminals are developing towards miniaturization, such as microphones, wireless headphones, etc., which require extremely small or micro circuits. In the production of small circuit boards, traditional chip resistors and capacitors cannot meet the needs of small-volume circuit production. Chip electronic components are currently widely used in electronic products.

[0003] During the circuit manufacturing process of existing thin film resistor products, the resistor layer is prone to cracking when used at the application end, causing the resistor to fail and affecting the efficiency and quality of circuit board manufacturing. Summary of the invention

[0004] The present invention provides a composite metal foil, a metal-clad laminate, a chip and a circuit board, which can improve the compactness of a functional layer, improve the toughness of the composite metal foil and avoid cracking of the functional layer during the circuit board lamination process.

[0005] In a first aspect, an embodiment of the present invention provides a composite metal foil, comprising: a base layer and a functional layer which are stacked; the thermal conductivity of the base layer is greater than 400 W / mK.

[0006] Optionally, the thermal conductivity of the base layer is between 400 W / mK and 450 W / mK.

[0007] Optionally, a heat insulation layer is provided on a side of the base layer close to and / or away from the functional layer.

[0008] Optionally, within a unit area, the ratio of the number of grains to the number of grain boundaries in the base layer is 0.1-2.

[0009] Optionally, among all the grains of the base layer within a unit area, the proportion of grains with single crystal orientation is 70-100%.

[0010] Optionally, the composite metal foil further includes a buffer layer, and the buffer layer, the base layer and the functional layer are stacked separately.

[0011] Optionally, the material of the base layer includes one or more materials selected from the group consisting of copper, gold, silver, iron, aluminum, graphite, conductive polymers and carbon fiber composites; and / or the functional layer includes at least one element selected from the group consisting of nickel, chromium, zinc, aluminum, iron, titanium, phosphorus, tin, oxygen, nitrogen and copper.

[0012] Optionally, the chromium content in the functional layer ranges from 10% to 40%, and the nickel content ranges from 60% to 90%.

[0013] Optionally, the thickness of the base layer is 5 to 50 μm; and / or the roughness Rz of the surface of the base layer on a side close to the functional layer is in the range of 0.5 to 10 μm.

[0014] Optionally, the composite metal foil further includes an adjustment layer, which is arranged on a side of the functional layer away from the base layer, and is used to enhance the bonding force between the base layer and the substrate during lamination.

[0015] In a second aspect, an embodiment of the present invention provides a metal-clad laminate, wherein the metal-clad laminate comprises the composite metal foil described in any embodiment of the present invention.

[0016] In a third aspect, an embodiment of the present invention provides a chip, wherein the chip comprises the composite metal foil described in any embodiment of the present invention.

[0017] In a fourth aspect, an embodiment of the present invention provides a circuit board, wherein the circuit board comprises the composite metal foil described in any embodiment of the present invention.

[0018] The technical solution provided by the embodiment of the present invention is that the composite metal foil includes a base layer and a functional layer which are stacked; the thermal conductivity of the base layer is greater than 400W / mK. By limiting the thermal conductivity of the base layer material, the deposition speed of the thin film material is affected, the compactness of the functional layer during sputtering is improved, and the toughness of the composite metal foil is improved, so that the cracking of the functional layer during the circuit board lamination process can be avoided, the use requirements are met, and the circuit processing accuracy is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a composite metal foil provided by an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention;

[0023] Figure 5 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention;

[0024] Figure 6 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention;

[0025] Figure 7A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention;

[0026] Figure 8 A schematic structural diagram of another composite metal foil provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Figure 1 A schematic diagram of the structure of a composite metal foil provided by an embodiment of the present invention, see Figure 1 , including: a stacked base layer 110 and a functional layer 120; the thermal conductivity of the base layer 110 is greater than 400 W / mK.

[0029] Specifically, the base layer 110 is a conductive material, such as one or more metals selected from copper, aluminum, gold, silver and iron. The functional layer 120 has electrical properties, and the functional layer 120 can realize the function of a resistor or a capacitor through material and structural design. For example, the functional layer 120 uses a resistive material as a resistive layer, and the resistive layer acts as a resistor. The functional layer 120 can also be designed structurally, such as an insulating material sandwiched between two layers of conductive materials as a capacitor layer, and the functional layer 120 acts as a capacitor. The functional layer 120 can be a resistive material or a capacitive material, such as at least one element or a combination of two elements selected from nickel, chromium, zinc, aluminum, iron, titanium, phosphorus, tin, oxygen, nitrogen and copper. The side of the base layer 110 close to the functional layer is usually a matte surface, that is, a rough surface. A vacuum magnetron sputtering process is used to sputter the metal material of the target onto the base layer 110 to form the functional layer 120. By increasing the thermal conductivity of the substrate layer 110, the temperature of the substrate layer 110 during sputtering is increased, wherein the thermal conductivity is a parameter to measure the quality of the thermal conductivity of the material, which indicates the amount of heat passing through a unit area and a unit temperature difference in a unit time. When the temperature of the substrate layer 110 is high, the mobility of the deposited atoms is large, the atomic mobility is strong, and it is easy to aggregate and nucleate, and finally form a polycrystalline or high crystallization film. In other words, when the substrate layer 110 has good thermal conductivity, heat can be transferred faster and more evenly, so that the temperature distribution of the substrate layer 110 is uniform, which is conducive to the uniform migration and aggregation of the deposited atoms on the substrate surface, thereby improving the compactness of the sputtered layer. The change in the temperature of the substrate layer 110 will affect the chemical reaction rate and the deposition behavior of ions and neutral particles on the substrate surface. The substrate layer 110 material with good thermal conductivity can control the temperature more accurately, thereby affecting the deposition speed and uniformity of the thin film material, helping the uniform deposition of the thin film material, reducing the formation of non-uniform deposition or dendritic structure, and helping to improve the compactness of the sputtered layer.

[0030] Optionally, the thermal conductivity of the base layer can be changed by using different conductive element materials, or by changing the alloying of elemental metals, the purity of metal materials, surface treatment processes, microstructure control, and other thermal conductive material composites to improve the thermal conductivity.

[0031] Exemplarily, the base layer 110 can be made of copper. By adjusting the material and internal structure of the base copper, a base layer 110 with high thermal conductivity is formed. By limiting the thermal conductivity of the base layer 110 to be greater than 400W / mK, the non-uniform deposition or the formation of the dendritic structure during the sputtering of the functional layer 120 is reduced, and the bonding density of the functional layer 120 is increased, thereby improving the compactness of the functional layer 120. By increasing the compactness of the functional layer 120, the toughness of the composite metal foil is improved to reduce the risk of cracking during the lamination of the circuit board. It should be noted that the thermal conductivity of the base layer 110 can be measured by a thermal conductivity meter, or calculated using a numerical method or an empirical formula. To calculate the thermal conductivity of the base layer 110 at different temperatures, the empirical formula λ(T)=λ(T0)×(1+α(T-T0)) can be used, where λ(T) represents the thermal conductivity at temperature T, λ(T0) represents the thermal conductivity at temperature T0, α is the temperature coefficient, and T0 is the reference temperature (generally 20°C).

[0032] The technical solution provided by the embodiment of the present invention is that the composite metal foil includes a base layer and a functional layer which are stacked; the thermal conductivity of the base layer 110 is greater than 400W / mK. By limiting the thermal conductivity of the base layer material, the deposition speed of the thin film material is affected, the compactness of the functional layer 120 during sputtering is improved, and the toughness of the composite metal foil is improved, so that the cracking of the functional layer during the circuit board lamination process can be avoided, the use requirements are met, and the circuit processing accuracy is improved.

[0033] In some embodiments, by adjusting the material and internal structure of the base layer 110, optionally, the thermal conductivity of the base layer 110 ranges from 400W / mK to 450W / mK. For example, the thermal conductivity of the base layer 110 is 400W / mK, 410W / mK, 420W / mK, 430W / mK, 440W / mK or 450W / mK. The thermal conductivity is an important physical quantity for measuring the thermal conductivity of a material. The thermal conductivity of the base layer 110 is set within the range of 400W / mK-450W / mK, which can effectively conduct heat, facilitate uniform deposition of thin film materials, reduce non-uniform deposition or the formation of dendritic structures, thereby reducing the porosity inside the functional layer 120, making the material structure more compact, improving the density of the functional layer 120, and avoiding the problem of increased material costs due to a larger thermal conductivity.

[0034] In some embodiments, the ratio of the number of grains to grain boundaries in the base layer per unit area is 0.1 to 2, wherein the unit area may be an area observed by a scanning electron microscope (SEM) at a preset magnification, or may be a preset specified area, for example, the unit area may be 5 μm 2 , 10μm 2 , 15μm 2Size or other area size. It should be noted that the unit area can be set according to the observation equipment or observation method, and the specific size value is not limited here. Specifically, the grain is the basic component unit in the crystal material, usually with a regular geometric shape and a certain orientation. The grain boundary is the interface area between adjacent grains. Due to the orientation difference of the grains, the atomic arrangement at the grain boundary is relatively chaotic and has a higher energy state. The smaller the grain size, the more grains there are in a unit volume, and accordingly, the number of grain boundaries will also increase. This is because the grain boundary is the dividing line between the grains, and the increase in the number of grains will inevitably lead to an increase in the number of grain boundaries. By adjusting the grain size, the ratio of the number of grains to grain boundaries in the base layer 110 within a certain unit area is between 0.1 and 2. Increasing the grain size will correspondingly reduce the number of grain boundaries, and the grain boundary is an obstacle unit for heat conduction. Therefore, the thermal conductivity can be increased by increasing the grain size.

[0035] At the same time, the ratio of the number of grains to grain boundaries of 0.1 to 2 can provide a suitable grain boundary density, avoiding excessively high grain boundary density, which may cause defects in the base layer 110, such as pores and cracks. The grain boundary density under the constraint conditions defined in the embodiment of the present invention helps to reduce the structural defects of the base layer 110. In addition, the appropriate amount of grain boundaries also helps to improve the thermal stability of the base layer 110. In a high temperature environment, the grain boundaries can serve as channels for atomic diffusion, promote the recrystallization and phase change process of the base layer 110 material, and thus maintain the organizational stability and thermal performance consistency of the base layer 110 material.

[0036] In some embodiments, within a unit area, among all the grains of the base layer 110, the proportion of single crystal oriented grains is 70% to 100%. Specifically, the thermal conductivity of the base layer 110 is mainly determined by its internal microstructure, especially the movement of lattice vibrating phonons and free electrons. As part of the microstructure, grain orientation has an important influence on the propagation path and scattering frequency of phonons. When the grains are oriented in the same way, the propagation path of phonons (or electrons) in the material is smoother, reducing the scattering and energy loss caused by differences in grain boundary orientation. This ordered microstructure is conducive to the rapid transfer of heat, thereby further improving the thermal conductivity of the material.

[0037] Furthermore, single crystal oriented grains generally have higher strength and toughness because they have fewer internal defects (such as grain boundaries), which reduces the path for crack propagation. A higher proportion of single crystal orientation can improve the overall mechanical properties of the substrate layer 110 and make the performance of the material more uniform in all directions. Single crystal oriented grains reduce the number of crack sources such as grain boundaries, and also reduce the risk of fracture of the substrate layer 110 during application, thereby increasing the support of the substrate layer 110 to the functional layer 120, and also reducing the risk of fracture of the functional layer 120 during application.

[0038] In some embodiments, Figure 2 A schematic diagram of the structure of another composite metal foil provided in an embodiment of the present invention, Figure 3 A schematic diagram of the structure of another composite metal foil provided in an embodiment of the present invention, Figure 4 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention is shown in FIG. Figure 2-4 , a heat insulating layer 210 is disposed on the side of the base layer 110 close to and / or away from the functional layer. Specifically, the heat insulating layer 210 may be metal or non-metal, which reduces the heat dissipation efficiency of the base layer 110, thereby increasing the temperature of the base layer 110 during sputtering, and can also improve the compactness of the sputtered layer, reduce the formation of non-uniform deposition or dendritic structure, and is conducive to improving the compactness of the sputtered layer.

[0039] In some embodiments, the material of the functional layer 120 can be at least one element or a combination of two elements selected from nickel, chromium, zinc, aluminum, iron, titanium, phosphorus, tin, oxygen, nitrogen and copper. The functional layer 120 forms a resistor after being etched. In some embodiments, the functional layer 120 can be made of nickel-chromium alloy, which has the advantages of excellent conductivity, corrosion resistance, high temperature stability and adjustable resistivity. By adjusting the ratio of nickel and chromium, the content of nickel and chromium in the functional layer 120 can be controlled, thereby affecting the resistivity and compactness of the resistor layer. In the embodiment of the present invention, the content of the functional layer 120 is in the range of 10% to 40%, for example, the content of chromium is in the range of 10%, 15%, 20%, 25%, 30%, 35% or 40%, and the content of nickel is in the range of 60% to 90%, for example, the content of nickel is in the range of 60%, 65%, 70%, 75%, 80%, 85% or 90%, so that the compactness of the resistor layer can be further adjusted.

[0040] In some embodiments, the base layer 110 may include one or more metals selected from copper, aluminum, gold, silver, iron and aluminum, and may also include one or more non-metals selected from graphite, conductive polymers and carbon fiber composite materials. Among them, the thickness of the base layer 110 is 2μm-80μm. By setting the thickness of the base layer 110 to 2μm-80μm, the requirements for the production of fine circuits of printed circuit boards can be met. In other embodiments, the thickness of the base layer 110 can be set to other values ​​according to actual use requirements, which will not be described in detail here. The functional layer 120 can be at least one element or a combination of two elements selected from nickel, chromium, zinc, aluminum, iron, titanium, phosphorus, tin, oxygen, nitrogen and copper, which can act as a resistor. The thickness of the functional layer 120 is set according to the resistance value requirements, which will not be described in detail here. When the composite metal foil is used as an embedded resistor copper foil, it is mainly a double-layer structure. The base layer 110 can be a copper layer, and the functional layer 120 is a resistor layer. The copper layer is used as the conductor of the circuit board, and the resistor layer provides resistance. After etching, the copper layer is etched to break the circuit to form a resistor in the circuit.

[0041] In some embodiments, the roughness Rz of the surface of one side of the substrate layer 110 close to the functional layer 120 can be in the range of 0.5μm-10μm. For example, the roughness Rz is 0.5μm, 1.5μm, 2.5μm, 3.5μm, 4.5μm, 5.5μm, 6.5μm, 7.5μm, 8.5μm, 9.5μm or 10μm. Too small roughness increases the difficulty of preparation in the process and also affects the bonding force between the substrate layer 110 and the functional layer 120. The functional layer 120 is processed by vacuum sputtering, chemical plating, water electroplating, etc., and the roughness Rz of the first surface is controlled at 0.5μm-10μm, which can meet the bonding force between the substrate layer 110 and the functional layer 120, prevent the functional layer 120 from falling off, and balance the influence of square resistance uniformity, thereby improving the square resistance uniformity and density of the functional layer.

[0042] In some embodiments, the composite metal foil further includes at least one of a transition layer, a barrier layer, and an adjustment layer in a stacked arrangement. The transition layer is used to improve the bonding strength between adjacent film layers, the barrier layer is used to prevent diffusion bonding of adjacent film layers at high temperatures, and the adjustment layer is used to increase the bonding strength between the functional layer 120 and the substrate when pressed together. The stacking arrangement here is not limited to an adjacent contact arrangement, nor is it limited to a sequential stacking relationship, but only describes the relative spatial relationship between the layers. For example, Figure 5 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention is shown in FIG. Figure 5 In the embodiment of the present invention, a transition layer 310 is provided, and the transition layer 310 is provided between the base layer 110 and the functional layer 120, for example, the transition layer 310 is provided between the base layer 110 and the thermal insulation layer 210, and or the transition layer 310 is provided between the functional layer 120 and the thermal insulation layer 210. The transition layer 310 is used to improve the bonding force between adjacent film layers.

[0043] In some other embodiments, the composite metal foil further includes a barrier layer 410, which is disposed between the substrate layer 110 and the functional layer 120. The barrier layer 410 is used to prevent diffusion bonding of adjacent film layers at high temperatures. In this embodiment, exemplarily, the barrier layer 410 is disposed between the thermal insulation layer 210 and the functional layer 120. In some embodiments, the barrier layer 410 can be disposed between the thermal insulation layer 210 and the transition layer 310, or between the transition layer 310 and the substrate layer 110. The barrier layer 410 can effectively isolate adjacent film layers to avoid the problem of bonding caused by mutual diffusion of adjacent film layers at high temperatures. Exemplarily, the barrier layer includes a high temperature resistant layer, which is an organic high temperature resistant layer; or, the high temperature resistant layer is made of any one or more materials selected from tungsten, chromium, zirconium, titanium, nickel, molybdenum, cobalt and graphite. Preferably, the high temperature resistant layer is a single-layer alloy structure, or a multi-layer structure composed of a single metal layer, or a multi-layer structure composed of an alloy layer and a single metal layer. Specifically, the single-layer alloy structure is a single-layer structure made of an alloy material, for example, a single-layer structure made of a tungsten-chromium alloy; the multi-layer structure composed of a single metal layer is a multi-layer structure composed of multiple single-layer structures, each of which is made of a metal, for example, a multi-layer structure composed of a tungsten metal layer and a chromium metal layer; the multi-layer structure composed of an alloy layer and a single metal layer is a multi-layer structure composed of multiple single-layer structures, each of which is composed of a metal or alloy material, for example, a multi-layer structure composed of a zirconium metal layer and a tungsten-chromium alloy layer. Optionally, the composite metal foil also includes an adjustment layer 510, which is arranged on the surface of the functional layer 120 away from the base layer 110, and the adjustment layer 510 is used to increase the bonding force between the functional layer 120 and the substrate after lamination, and the adjustment layer 510 can be a silane coupling agent, a titanate coupling agent, a zirconium aluminate coupling agent, a phosphate coupling agent, a borate coupling agent, an organic chromium coupling agent or other coupling agent types.

[0044] In some embodiments, the composite metal foil further includes a buffer layer 610 , and the buffer layer 610 , the base layer 110 , and the functional layer 120 are stacked separately. Figure 6 A schematic diagram of the structure of another composite metal foil provided in an embodiment of the present invention, Figure 7 A schematic diagram of the structure of another composite metal foil provided in an embodiment of the present invention, Figure 8 A schematic diagram of the structure of another composite metal foil provided by an embodiment of the present invention is shown in FIG. Figure 6-8 The buffer layer 610 can be arranged between the base layer 110 and the functional layer 120, can be arranged on the side of the base layer 110 away from the functional layer 120, and can also be arranged on the side of the functional layer 120 away from the base layer 110. When the composite metal foil also includes other film layers, such as a thermal insulation layer, a transition layer, a barrier layer, and an adjustment layer, the positional relationship between the buffer layer and the other film layers is not limited. The buffer layer is used to improve the stress buffering performance of the composite metal foil. The buffer layer can be selected from a material with good ductility and compatible with copper and nickel-chromium, such as titanium or chromium.

[0045] The thermal conductivity of copper foil can be measured with a thermal conductivity meter, or calculated using numerical methods or empirical formulas. To calculate the thermal conductivity of copper foil at different temperatures, the empirical formula λ(T)=λ(T0)×(1+α(T-T0)) can be used, where λ(T) represents the thermal conductivity at temperature T, λ(T0) represents the thermal conductivity at temperature T0, α is the temperature coefficient, and T0 is the reference temperature (usually 20°C).

[0046] Example 1

[0047] An embodiment of the present invention provides a composite metal foil, comprising a stacked base layer 110 and a functional layer 120, wherein the base layer 110 is a copper foil, the functional layer 120 is a resistor layer, the functional layer 120 comprises nickel, chromium and other elements, wherein the nickel content is 69%, the chromium content is 22%, the thermal conductivity of the copper foil is 436 W / mK, and the thickness of the functional layer 120 is 181 nm.

[0048] Example 2

[0049] The embodiment of the present invention provides a composite metal foil, comprising a base layer 110, a functional layer 120 and a heat insulation layer 210 stacked together. Figure 2-Figure 4 , wherein the base layer 110 is a silver foil, the functional layer 120 is a resistor layer, the functional layer 120 includes nickel, chromium and other elements, wherein the nickel content is 63%, the chromium content is 25%, the thermal conductivity of the silver foil is 420W / mK, and the thickness of the functional layer 120 is 225nm.

[0050] Example 3

[0051] The embodiment of the present invention provides a composite metal foil, comprising a stacked base layer 110, a functional layer 120, a heat insulating layer 210 and a buffer layer 610. Figure 2-Figure 4 , Figure 6-Figure 8 The buffer layer 610 can be arranged between the base layer 110 and the functional layer 120, can be arranged on the side of the base layer 110 away from the functional layer 120, or can be arranged on the side of the functional layer 120 away from the base layer 110. In the embodiment of the present invention, the thermal insulation layer 210 is arranged between the base layer 110 and the functional layer 120, and the buffer layer 610 is arranged on the side of the base layer 110 away from the functional layer 120, wherein the base layer 110 is copper foil, the functional layer 120 is a resistance layer, the functional layer 120 includes nickel, chromium and other elements, wherein the nickel content is 70%, the chromium content is 29%, the thermal conductivity of the copper foil is 412W / mK, and the thickness of the functional layer 120 is 245nm.

[0052] Comparative Example 1

[0053] An embodiment of the present invention provides a composite metal foil, comprising a stacked base layer 110 and a functional layer 120, wherein the base layer 110 is a copper layer, the functional layer 120 is a resistor layer, the resistor layer is made of nickel-chromium alloy, the thermal conductivity of the copper foil is 398 W / mK, and the thickness of the functional layer 120 is 91 nm.

[0054] Comparative Example 2

[0055] An embodiment of the present invention provides a composite metal foil, including a stacked base layer 110 and a functional layer 120, wherein the base layer 110 is a beryllium copper foil, the functional layer 120 is a resistor layer, the resistor layer is made of nickel-chromium alloy, the thermal conductivity of beryllium copper is 115 W / mK, and the thickness of the functional layer 120 is 1.4 μm.

[0056] The method of pressing the composite copper foil onto the circuit board is to use a double-opening press at 185°C and 120kg / cm 2 The composite copper foils were pressed onto the PTFE substrates at a pressure of 100° for 85 minutes. The test results are shown in Table 1.

[0057] Table 1 Performance of each embodiment and comparative example

[0058]

[0059] It can be seen that the thermal conductivity of the base layer of the composite metal foil in Examples 1-3 of the present invention is greater than 400 W / mK, which improves the density of the functional layer 120 during sputtering, makes the composite metal foil more resilient at the same resistance value, avoids cracking of the functional layer during the circuit board lamination process, meets the use requirements, and is conducive to improving the circuit processing accuracy.

[0060] The embodiment of the present invention further provides a metal-clad laminate, which is generally formed by laminating a metal foil and a thermoplastic liquid crystal polymer film or other types of insulating materials. The metal foil is a composite metal foil of any embodiment of the present invention, and thus has the same beneficial effects, which will not be described in detail herein.

[0061] The embodiment of the present invention further provides a chip, which is a silicon-based device on which electronic components such as transistors, resistors, capacitors, etc. are integrated. It is a basic component of electronic equipment and has a good degree of integration. Since it has the composite metal foil of any embodiment of the present invention, it has the same beneficial effects, which will not be described in detail here.

[0062] The embodiment of the present invention further provides a circuit board, which is also called a printed circuit board, a PCB board, an electronic board or a circuit board, and is an important electronic component, including the composite metal foil of any embodiment of the present invention, and the composite metal foil is used to make a resistor circuit. When making the resistor circuit, the base layer 110 and the functional layer 120 of the composite metal foil are etched according to a preset resistor circuit image to obtain the desired resistor circuit. The circuit board of the embodiment of the present invention has the same beneficial effects as the composite metal foil of any embodiment of the present invention, and will not be described in detail here.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite metal foil, characterized in that: include: A base layer and a functional layer are stacked; the thermal conductivity of the base layer is greater than 400 W / mK.

2. The composite metal foil according to claim 1, characterized in that: The thermal conductivity of the base layer is between 400 W / mK and 450 W / mK.

3. The composite metal foil according to claim 1, characterized in that: A heat insulation layer is arranged on a side of the substrate layer close to and / or away from the functional layer.

4. The composite metal foil according to claim 1, characterized in that: The ratio of the number of crystal grains to the number of grain boundaries in the base layer is 0.1 to 2 per unit area.

5. The composite metal foil according to claim 4, characterized in that: Among all the crystal grains of the base layer within a unit area, the crystal grains with single crystal orientation account for 70-100%.

6. The composite metal foil according to claim 1, characterized in that: The composite metal foil further includes a buffer layer, and the buffer layer, the base layer and the functional layer are stacked separately.

7. The composite metal foil according to claim 3, characterized in that: The material of the base layer includes one or more materials selected from the group consisting of copper, gold, silver, iron, aluminum, graphite, conductive polymers, and carbon fiber composite materials; and / or the functional layer includes at least one element selected from the group consisting of nickel, chromium, zinc, aluminum, iron, titanium, phosphorus, tin, oxygen, nitrogen, and copper.

8. The composite metal foil according to claim 7, characterized in that: The content of chromium in the functional layer ranges from 10% to 40%, and the content of nickel ranges from 60% to 90%.

9. The composite metal foil according to any one of claims 1 to 8, characterized in that: The thickness of the base layer is 5 to 50 μm; and / or the roughness Rz of the surface of the base layer on a side close to the functional layer is in the range of 0.5 to 10 μm.

10. The composite metal foil according to any one of claims 1 to 8, characterized in that: It also includes an adjustment layer, which is arranged on a side of the functional layer away from the base layer, and is used to enhance the bonding force between the base layer and the substrate during lamination.

11. A metal-clad laminate, characterized in that: The metal-clad laminate comprises the composite metal foil according to any one of claims 1 to 10.

12. A chip, characterized in that: The chip comprises the composite metal foil according to any one of claims 1-10.

13. A circuit board, characterized in that: The circuit board comprises the composite metal foil according to any one of claims 1-10.

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