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

Abstract

The invention discloses a composite metal foil, a metal-clad laminate and a circuit board. The composite metal foil comprises a resistance layer and a conducting layer, the resistance layer is arranged on the first surface of the conducting layer, the first surface is provided with a plurality of protruding structures, the composite metal foil is sliced in the first direction, and the ratio of the number of the standard protruding structures to the total number of the protruding structures is larger than 60% within the preset area; wherein the difference value between the maximum width W2 of the standard bulge structure along the second direction and the maximum contact width W1 of the standard bulge structure and the conductive layer is within a first preset range, and the first preset range is that (W2-W1) is more than or equal to 0 mu m and less than or equal to 30 mu m; the first direction is a direction from the conductive layer to the resistive layer, and the second direction is a direction perpendicular to the first direction. According to the invention, holes and cracks of the resistive layer are avoided, the continuity of the resistive layer is improved, and the resistance uniformity is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of composite metal foils, and in particular to a composite metal foil, a metal-clad laminate and a circuit board. Background Art

[0002] With the continuous advancement of the electronics industry and information technology, electronic components are developing towards high performance and miniaturization. However, electronic components will generate heat during operation. As the operating temperature increases, the electronic components will not be able to operate normally. Therefore, it is necessary to control the temperature of the electronic components to keep them operating normally. At present, some circuit boards are equipped with an embedded thin film thermistor layer to reduce the overall volume and thickness of the circuit board, and to perform real-time thermal management monitoring of the components of the circuit board.

[0003] When the existing thermistor copper foil is used to make a circuit board, the resistance layer is connected to the circuit board. However, the resistance layer is extremely thin, and the resistance value uniformity of different positions of the raw material will be poor during the formation process, which cannot meet the design requirements of the circuit board organization, resulting in poor circuit board production quality. Summary of the invention

[0004] The invention provides a composite metal foil, a metal-clad laminate and a circuit board, so as to avoid holes and cracks in a resistor layer, improve the continuity of the resistor layer, and further improve the uniformity of the resistor.

[0005] According to one aspect of the present invention, there is provided a composite metal foil, the composite metal foil comprising:

[0006] A resistor layer and a conductive layer, the resistor layer is arranged on the first surface of the conductive layer, and the first surface is provided with a plurality of protruding structures, the composite metal foil is sliced ​​along a first direction, and within a preset area, the ratio of the number of standard protruding structures to the total number of protruding structures is greater than 60%; wherein, the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 of the standard protruding structure and the conductive layer is within a first preset range, and the first preset range is 0μm≤(W2-W1)≤30μm; the first direction is the direction from the conductive layer to the resistor layer, and the second direction is a direction perpendicular to the first direction.

[0007] Furthermore, the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfies the following condition: 10 nm≤(W2-W1)≤2 μm.

[0008] Further, the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfy the following condition: 0.7≤W2 / W1≤1.3.

[0009] Furthermore, the maximum height H of the standard protruding structure and the maximum width W2 of the standard protruding structure along the second direction satisfy the following condition: 2 μm≤|H-W2|≤4 μm.

[0010] Furthermore, the maximum height H of the standard protruding structure and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfy the following condition: 50 nm ≤ (H-W1) ≤ 1.5 μm.

[0011] Furthermore, the standard protrusion structure includes at least one hollow protrusion structure, the hollow protrusion structure includes at least one hollow part, and within a preset area, the ratio of the number of first hollow protrusion structures to the total number of hollow protrusion structures is greater than 50%; wherein, the number of hollow parts included in the first hollow protrusion structure is less than 6.

[0012] Furthermore, the ratio of the number of the second hollow protruding structures to the total number of the hollow protruding structures is greater than 80%; wherein the number of hollow parts included in the second hollow protruding structure is greater than or equal to 2 and less than or equal to 5.

[0013] Furthermore, the thickness of the resistance layer ranges from 50 nm to 3 μm.

[0014] Furthermore, the roughness Rz of the first surface of the conductive layer is in the range of 1-7 μm; wherein the first surface is the surface of the conductive layer close to the resistance layer.

[0015] Furthermore, the composite metal foil further includes an adjustment layer, and the adjustment layer is arranged on a side of the resistance layer away from the conductive layer.

[0016] Furthermore, the resistance layer is a resistance layer with a negative temperature coefficient, and within any 25° C. change range, the resistance value change rate of the resistance layer is greater than 5%.

[0017] Furthermore, the temperature is increased from 25° C. to 150° C. and then decreased to 25° C. for one temperature cycle, and after at least one temperature cycle, the resistance value recovery deviation of the resistor layer is less than 10%.

[0018] According to another aspect of the present invention, there is provided a metal-clad laminate, the metal-clad laminate comprising the composite metal foil described in any one of the above embodiments.

[0019] According to another aspect of the present invention, a circuit board is provided. The circuit board includes the composite metal foil described in any one of the above embodiments.

[0020] The composite metal foil provided by an embodiment of the present invention is arranged in a preset area, and on the first surface of the conductive layer, the ratio of the number of standard protrusion structures to the total number of protrusion structures is greater than 60%; wherein, the difference between the maximum width W2 of the standard protrusion structure along the second direction and the maximum contact width W1 of the standard protrusion structure and the conductive layer is within a first preset range, and the first preset range is 0μm≤(W2-W1)≤30μm. Within this range, in the process of manufacturing the resistor layer with the first surface of the conductive layer as the substrate, the area of ​​the first surface that cannot be covered by the resistor layer can be reduced, the continuity of the resistor layer is improved, and the appearance of holes and cracks in the resistor layer is effectively avoided, thereby improving the square resistance uniformity of the resistor layer.

[0021] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 is a schematic structural diagram of a composite metal foil provided according to an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of a partial slice structure of a composite metal foil provided according to an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of a slice structure of a composite metal foil protrusion structure provided according to an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of the structure of another composite metal foil provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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 only 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 should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] An embodiment of the present invention provides a composite metal foil. Figure 1 is a schematic diagram of the structure of a composite metal foil provided according to an embodiment of the present invention, Figure 2 is a schematic diagram of a partial slice structure of a composite metal foil provided in an embodiment of the present invention, Figure 3 is a schematic diagram of a slice structure of a composite metal foil protrusion structure provided according to an embodiment of the present invention, with reference to Figure 1-Figure 3 The composite metal foil includes: a resistor layer 10 and a conductive layer 20. The resistor layer 10 is arranged on the first surface of the conductive layer 20, and the first surface is provided with a plurality of protrusion structures 201. The composite metal foil is sliced ​​along a first direction, and within a preset area, the ratio of the number of standard protrusion structures to the total number of protrusion structures 201 is greater than 60%. Among them, the difference between the maximum width W2 of the standard protrusion structure along the second direction and the maximum contact width W1 of the standard protrusion structure and the conductive layer is within a first preset range, and the first preset range is 0μm≤(W2-W1)≤30μm. The first direction is the direction from the conductive layer 20 to the resistor layer 10, and the second direction is a direction perpendicular to the first direction.

[0030] The conductive layer 20 may be made of copper, gold, aluminum, silver, nickel, iron, manganese, platinum or other metal or non-metal conductive materials. Furthermore, the conductive layer 20 may have a thickness ranging from 10 to 50 μm.

[0031] The thickness of the conductive layer 20 can be set according to actual conditions. For example, the thickness of the conductive layer 20 is 18 μm. The conductive layer 20 can be made of electrolytic copper foil or rolled copper foil.

[0032] Optionally, the resistor layer 10 may be formed by physical vapor deposition, chemical vapor deposition, evaporation, electroplating, mixed plating or other deposition methods. Specifically, the resistor layer is formed on the first surface of the conductive layer 20 by one or more magnetron sputtering. The thickness of the resistor layer 10 is 50nm-800nm. The embodiment of the present invention only provides a specific method for forming the resistor layer 10, and does not limit this.

[0033] It should be noted that the preset area should be understood as a slice area of ​​any size selected after the composite metal foil is sliced. For example, the preset area can be 16 μm 2 , 20μm 2 、32μm 2 , 50μm 2 , 100μm 2 , 200μm 2 The observation range.

[0034] Specifically, when the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 of the standard protruding structure and the conductive layer is greater than or equal to zero and less than or equal to 30 μm, it means that the cross section of the standard protruding structure along the first direction is a structure that is wide at the top and narrow at the bottom. In the process of manufacturing the resistor layer 10, the appearance of holes and cracks in the resistor layer 10 can be effectively reduced, the continuity of the resistor layer 10 can be improved, and the uniformity of square resistance can be improved. Furthermore, by making the ratio of the number of standard protruding structures to the total number of protruding structures 201 greater than 60% within any preset area, the probability of holes in the resistor layer 10 can be effectively reduced, the continuity of the resistor layer 10 can be improved, and the uniformity of square resistance can be improved.

[0035] The composite metal foil provided by the embodiment of the present invention is arranged in a preset area, and the ratio of the number of standard protrusion structures to the total number of protrusion structures 201 on the first surface of the conductive layer 20 is greater than 60%. Among them, the difference between the maximum width W2 of the standard protrusion structure along the second direction and the maximum contact width W1 between the standard protrusion structure and the conductive layer is within a first preset range, and the first preset range is 0μm≤(W2-W1)≤30μm. Within this range, in the process of making the resistor layer 10 with the first surface of the conductive layer 20 as the substrate, the area of ​​the first surface that cannot be covered by the resistor layer 10 can be reduced, the continuity of the resistor layer 10 is improved, and holes and cracks in the resistor layer 10 are effectively avoided, thereby improving the square resistance uniformity of the resistor layer 10.

[0036] For further reference, Figure 3 , the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfies the following condition: 10 nm ≤ (W2-W1) ≤ 2 μm.

[0037] Specifically, the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 of the standard protruding structure and the conductive layer is set to meet the following conditions: 10nm≤(W2-W1)≤2μm, which can make the formed standard protruding structure more regular, further ensure the continuity of the resistance layer, and also help to improve the bonding strength between the composite metal foil and the substrate, thereby improving the production quality of the circuit board.

[0038] For further reference, Figure 3 , the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfy the following condition: 0.7≤W2 / W1≤1.3.

[0039] Specifically, the ratio of the maximum width W2 of the standard protruding structure along the second direction to the maximum contact width W1 of the standard protruding structure and the conductive layer is set to be greater than or equal to 0.7 and less than or equal to 1.3, so as to avoid the formation of a crown-shaped standard protruding structure, thereby making the formed standard protruding structure more uniform and regular. When processing the resistance layer, the resistance layer covers a larger area of ​​the first surface below the standard protruding structure, thereby ensuring the continuity of the resistance layer and improving the bonding force between the composite metal foil and the substrate.

[0040] For further reference, Figure 3 , a maximum height H of the standard protruding structure and a maximum width W2 of the standard protruding structure along the second direction satisfy the following condition: 2 μm≤|H-W2|≤4 μm.

[0041] Specifically, the maximum height H of the standard protruding structure and the maximum width W2 of the standard protruding structure along the second direction are set to satisfy the following condition: 2μm≤|H-W2|≤4μm, so that the difference between the maximum height H of the standard protruding structure and the maximum width W2 of the standard protruding structure along the second direction is smaller. Exemplarily, the maximum height of the formed standard protruding structure may be greater than the maximum width along the second direction, or may be less than the maximum width along the second direction, so that the types of standard protruding structures formed are more abundant, the roughness of the standard protruding structure is adjusted, the cross-sectional area of ​​the surface resistance layer of the standard protruding structure is increased, and the current carrying capacity of the resistance layer is increased.

[0042] For further reference, Figure 3 , the maximum height H of the standard protruding structure and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfy the following condition: 50nm≤(H-W1)≤1.5μm.

[0043] Specifically, the maximum height H of the standard protruding structure and the maximum contact width W1 between the standard protruding structure and the conductive layer are set to meet the following conditions: 50nm≤(H-W1)≤1.5μm, so that the difference between the maximum height H of the standard protruding structure and the maximum contact width W1 between the standard protruding structure and the conductive layer is smaller, the roughness is adjusted, and the formed standard protruding structure is more regular, while ensuring the continuity of the resistance layer, the bonding force between the composite metal foil and the substrate is improved.

[0044] For further reference, Figure 2 and Figure 3 The protruding structure 201 includes at least one hollow protruding structure 202, and the hollow protruding structure 202 includes at least one hollow portion 2011. Within a preset area, the ratio of the number of first hollow protruding structures to the total number of hollow protruding structures is greater than 50%; wherein the number of hollow portions 2011 included in the first hollow protruding structure is less than 6.

[0045] Here, one may be understood as one or more than one. For example, the protrusion structure 201 may include one or more hollow protrusion structures 202 .

[0046] Specifically, the number of hollow protrusion structures 202 including less than 6 hollow portions 2011 accounts for more than 50% of the total number of hollow protrusion structures 202, which can effectively reduce the number of hollow portions 2011 in the protrusion structure 201. Therefore, in the process of manufacturing the resistance layer 10, the probability of forming holes and cracks in the resistance layer 10 at the position of the hollow portions 2011 is reduced due to reducing the number of hollow portions 2011 in the protrusion structure 201, thereby improving the continuity of the resistance layer 10.

[0047] For further information, please refer to Figure 3 , the ratio of the number of the second hollow protruding structures to the total number of the hollow protruding structures 202 is greater than 80%; wherein the number of the hollow portions 2011 included in the second hollow protruding structure is greater than or equal to 2 and less than or equal to 5.

[0048] Specifically, the number of hollow protrusion structures 202 including hollow portions 2011 greater than or equal to 2 and less than or equal to 5 accounts for more than 80% of the total number of hollow protrusion structures 202, which can further reduce the number of hollow portions 2011 in the protrusion structure 201. In the process of manufacturing the resistor layer 10, it can effectively avoid the formation of holes and cracks in the resistor layer 10 at the positions of the hollow portions 2011 due to the large number of hollow portions 2011 in the protrusion structure, thereby further improving the continuity of the resistor layer 10.

[0049] Furthermore, the thickness of the resistance layer is 50 nm-3 μm.

[0050] Specifically, the resistance layer is set to have a relatively thin thickness. After the composite metal foil is manufactured into a circuit board, the temperature of each device in the circuit board can be monitored without affecting the overall structure of the circuit board.

[0051] Furthermore, the roughness Rz of the first surface of the conductive layer is in the range of 1-7 μm; wherein the first surface is the surface of the conductive layer close to the resistance layer.

[0052] The roughness Rz is used to characterize the microscopic roughness of the surface of the conductive layer. Specifically, the average value of the five largest profile peak heights and the average value of the five largest profile valley depths within the sampling length are usually taken as the roughness Rz. The range of the roughness Rz of the first surface of the conductive layer is set to 1-7 μm, which can effectively improve the bonding force between the composite metal foil and the substrate, thereby making the bonding between the composite metal foil and the substrate tighter.

[0053] Optionally, the material of the resistance layer includes Ni (nickel), Cr (chromium), Zn (zinc), Al (aluminum), Sn (tin), O (oxygen), N (nitrogen), C (carbon), Cu (copper), Mn (manganese), Fe (iron) or other elements that can achieve good thermal sensitivity characteristics.

[0054] Specifically, the material of the resistor layer is nickel-iron oxide alloy. Nickel-iron oxide belongs to ferrite material, has good temperature sensitivity, and its resistance shows a stable nonlinear relationship with temperature change. It can be used to accurately measure temperature changes and can work in a wide temperature range. It has chemical and thermal stability, can maintain stable performance in long-term use or harsh environments (such as high temperature or high humidity), has relatively low manufacturing costs, and is suitable for large-scale production. By changing the ratio of nickel to iron or doping other elements (such as manganese and zinc), its resistance-temperature characteristics can be adjusted to meet specific application requirements.

[0055] Furthermore, in the resistor layer, the composition ratio is preferably: Fe (iron) content is less than 30%, Ni content is greater than 30%, and O content is less than 60%. Such a composition ratio can make etching easier on the one hand, and on the other hand can further improve temperature sensitivity and thermal stability, thereby improving the use quality of the composite metal foil.

[0056] When the composite metal foil is arranged in a circuit board for temperature monitoring, the thermal effect of the first resistor layer 10 is used to monitor the change of resistance, voltage, current or level of the circuit in the circuit board, thereby realizing heating monitoring and even feedback regulation of electronic components.

[0057] Furthermore, Figure 4 is a schematic diagram of the structure of another composite metal foil provided according to an embodiment of the present invention, Figure 4The composite metal foil further includes an adjustment layer 30 , which is disposed on a side of the resistance layer 10 away from the conductive layer 20 .

[0058] Specifically, adding the adjustment layer 30 to the composite metal foil can effectively enhance the bonding force between the composite metal foil pressed onto the substrate and the substrate, thereby preventing the composite metal foil from falling off.

[0059] Optionally, the material of the adjustment layer can be silane coupling agent, titanate coupling agent, aluminate coupling agent, phosphate coupling agent, modified epoxy resin, acrylic acid, modified rubber, modified thermoplastic polyimide or other materials. Specifically in this embodiment, the adjustment layer is a silane coupling agent, which is beneficial to ensure the mechanical properties and corrosion resistance of the resistor layer 10.

[0060] Furthermore, the resistance layer is a resistance layer with a negative temperature coefficient, and within any 25° C. change range, the resistance value change rate of the resistance layer is greater than 5%.

[0061] Specifically, the resistance layer is set to have a change rate greater than 5% after the resistance layer changes by 25°C from any temperature, which can improve the resistance layer's sensitivity to temperature changes. After the composite metal foil is made into a circuit board, the monitoring of each device in the circuit board is more accurate.

[0062] Furthermore, the temperature rises from 25° C. to 150° C. and then drops to 25° C. as one temperature cycle, and the resistance value recovery deviation of the resistor layer in at least one temperature cycle is less than 10%.

[0063] Here, at least once can be understood as once or more than once. The resistance recovery deviation can be understood as the difference between the resistance value of the resistor layer before the temperature rise and the resistance value after one temperature cycle.

[0064] Specifically, after one temperature cycle, the resistance value recovery deviation of the resistor layer is less than 10%, so that the temperature of the resistor layer can be raised and then restored to room temperature, and the resistance of the resistor layer can return to near the original resistance value, so that the resistance of the resistor layer can be reused to achieve temperature control, ensure working accuracy, improve working reliability, and the resistance of the resistor layer can change steadily with temperature changes, ensuring stable operation of the circuit. After multiple temperature cycles, the resistance value of the resistor layer can still be restored to near the initial value, and the resistance value still changes steadily, thereby ensuring that the composite metal foil has a longer service life.

[0065] Experimental Group 1

[0066] A composite metal foil comprises a conductive layer and a resistive layer, wherein the conductive layer is made of Cu, the base layer is 18 μm thick, the resistive layer is made of a nickel-iron oxide alloy, and the resistive layer is 530 nm thick. Under a scanning electron microscope, the ratio of the number of standard protruding structures to the total number of protruding structures is 78%, wherein the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 of the standard protruding structure and the conductive layer is in the range of 0.5 μm≤(W2-W1)≤2 μm.

[0067] Experimental Group 2

[0068] Based on test group 1, under the observation environment of a scanning electron microscope, the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfies the following condition: 200nm≤(W2-W1)≤1.5μm.

[0069] Experimental Group 3

[0070] Different from the experimental group 1, under the observation environment of the scanning electron microscope, the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 between the standard protruding structure and the conductive layer meet the following condition: 0.9≤W2 / W1≤1.1.

[0071] Control group 1

[0072] The composite metal foil comprises a conductive layer and a resistive layer, wherein the conductive layer is made of Cu, the base layer has a thickness of 18 μm, the resistive layer is made of Ni-Al alloy, and the resistive layer has a thickness of 800 nm. Under the observation environment of a scanning electron microscope, the ratio of the number of standard protruding structures to the total number of protruding structures is 15%, wherein the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 of the standard protruding structure and the conductive layer is in the range of 0 μm≤(W2-W1)≤6 μm.

[0073] Control group 2

[0074] Different from the control group 1, the material of the resistance layer is Ni-Mn alloy, and the thickness of the resistance layer is 3μm. Under the observation environment of the scanning electron microscope, the ratio of the number of standard protruding structures to the total number of protruding structures is 5%, wherein the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 of the standard protruding structure and the conductive layer is in the range of 0μm≤(W2-W1)≤7μm.

[0075] The composite metal foils of the test group and the control group were used to make samples, and were pressed on the semi-cured core layer at 185°C for 10 minutes. The copper layer was removed with an alkaline etching solution, and the samples were placed in a 105°C oven for 10 minutes to remove moisture after cleaning. Small grids of 2 cm × 2 cm were marked on the surface of the sample after alkaline etching to remove the copper. The square resistance of each grid was tested with a square resistance meter, and the square resistance uniformity was statistically measured to form a comparison table of square resistance uniformity of different test groups and control groups as shown in Table 1.

[0076] Table 1. Comparison of square resistance uniformity of different test groups and control groups

[0077]

[0078] It can be seen from the data in Table 1 that the composite metal foils of test groups 1 to 3 can have higher uniformity of square resistance, which is beneficial to improving the quality of use.

[0079] The embodiment of the present invention further provides a metal-clad laminated plate, which comprises the composite metal foil described in any one of the above embodiments. The metal-clad laminated plate described in the present invention has the same beneficial effects as the composite metal foil described in any embodiment of the present invention.

[0080] The embodiment of the present invention further provides a circuit board, which includes the composite metal foil described in any one of the above embodiments. The composite metal foil can be arranged on the circuit and component surface of the circuit board to measure the temperature of the circuit or component. The circuit board of the embodiment of the present invention includes the composite metal foil, and the resistance layer formed in the composite metal foil has better uniformity, which realizes accurate monitoring of each position in the circuit board, improves the temperature detection accuracy, and avoids damage to the circuit board due to excessive temperature.

[0081] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0082] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite metal foil, characterized in that: include: A resistor layer and a conductive layer, wherein the resistor layer is arranged on a first surface of the conductive layer, and the first surface is provided with a plurality of protruding structures, and the composite metal foil is sliced ​​along a first direction, and within a preset area, the ratio of the number of standard protruding structures to the total number of the protruding structures is greater than 60%; wherein the difference between the maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 of the standard protruding structure and the conductive layer is within a first preset range, and the first preset range is 0μm≤(W2-W1)≤30μm; the first direction is the direction from the conductive layer to the resistor layer, and the second direction is a direction perpendicular to the first direction.

2. The composite metal foil according to claim 1, characterized in that: A difference between a maximum width W2 of the standard protruding structure along the second direction and a maximum contact width W1 between the standard protruding structure and the conductive layer satisfies the following condition: 10 nm≤(W2-W1)≤2 μm.

3. The composite metal foil according to claim 1, characterized in that: The maximum width W2 of the standard protruding structure along the second direction and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfy the following condition: 0.7≤W2 / W1≤1.

3.

4. The composite metal foil according to claim 1, characterized in that: The maximum height H of the standard protruding structure and the maximum width W2 of the standard protruding structure along the second direction satisfy the following condition: 2 μm≤|H−W2|≤4 μm.

5. The composite metal foil according to claim 1, characterized in that: The maximum height H of the standard protruding structure and the maximum contact width W1 between the standard protruding structure and the conductive layer satisfy the following condition: 50 nm ≤ (H-W1) ≤ 1.5 μm.

6. The composite metal foil according to claim 1, characterized in that: The standard protrusion structure includes at least one hollow protrusion structure, and the hollow protrusion structure includes at least one hollow part. Within a preset area, the ratio of the number of first hollow protrusion structures to the total number of the hollow protrusion structures is greater than 50%; wherein the number of the hollow parts contained in the first hollow protrusion structure is less than 6.

7. The composite metal foil according to claim 6, characterized in that: The ratio of the number of the second hollow protruding structures to the total number of the hollow protruding structures is greater than 80%; wherein the number of the hollow parts included in the second hollow protruding structure is greater than or equal to 2 and less than or equal to 5.

8. The composite metal foil according to claim 1, characterized in that: The thickness of the resistance layer is in the range of 50 nm to 3 μm.

9. The composite metal foil according to claim 7, characterized in that: The roughness Rz of the first surface of the conductive layer is in the range of 1-7 μm; wherein the first surface is the surface of the conductive layer close to the resistance layer.

10. The composite metal foil according to claim 1, characterized in that: It also includes an adjustment layer, which is arranged on a side of the resistance layer away from the conductive layer.

11. The composite metal foil according to claim 1, characterized in that: The resistance layer is a resistance layer with a negative temperature coefficient. In any 25° C. change range, the resistance value change rate of the resistance layer is greater than 5%.

12. The composite metal foil according to claim 1, characterized in that: The temperature rises from 25° C. to 150° C. and then drops back to 25° C. for one temperature cycle, and the resistance value recovery deviation of the resistor layer is less than 10% in at least one temperature cycle.

13. A metal-clad laminate, characterized in that: The composite metal foil comprises the composite metal foil as described in any one of claims 1 to 12.

14. A circuit board, characterized in that: The composite metal foil comprises the composite metal foil as described in any one of claims 1 to 12.

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