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, a plurality of protruding structures are arranged on the first surface, each protruding structure comprises at least one hollow protruding structure, and each hollow protruding structure comprises at least one hollow part; the composite metal foil is sliced in the first direction, and within the preset area, the ratio of the number of the first hollowed-out protruding structures to the number of the protruding structures is larger than 50%; wherein the first direction is the direction in which the conductive layer points to the resistance layer, and the ratio of the total area of the hollowed-out parts in the first hollowed-out protruding structures to the area of the slices is smaller than 20%. The sheet resistance uniformity of the composite metal foil is improved, and the circuit manufacturing quality is 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 improve the square resistance uniformity of the composite metal foil and enhance the circuit manufacturing quality.

[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 protrusion structures, the protrusion structures include at least one hollow protrusion structure, and the hollow protrusion structure includes at least one hollow portion; the composite metal foil is sliced ​​along a first direction, and within a preset area, the ratio of the number of the first hollow protrusion structures to the number of the protrusion structures is greater than 50%; wherein the first direction is the direction from the conductive layer to the resistor layer, and the ratio of the total area of ​​the hollow portions in the first hollow protrusion structure to the slice area is less than 20%.

[0007] Further, the hollow portion includes a first hollow portion and a second hollow portion;

[0008] The first hollow portion is communicated with the outside, and the second hollow portion is located inside the hollow protruding structure.

[0009] Furthermore, the ratio of the number of the second hollow protruding structures to the number of the protruding structures is greater than 50%; wherein the number of the first hollow parts in the second hollow protruding structures is less than the number of the second hollow parts.

[0010] Furthermore, in the first hollow protrusion structure, the maximum length of the hollow portion is less than 4.4 μm.

[0011] Furthermore, in the first hollow protrusion structure, the ratio of the number of the third hollow parts to the total number of the hollow parts is greater than 60%; wherein the length-to-width ratio of the minimum circumscribed rectangle of the third hollow part is greater than 3.

[0012] Furthermore, in the first hollow protrusion structure, the ratio of the sum of the areas of the fourth hollow portions to the total area of ​​the hollow portions is greater than 30%; wherein the maximum length of the fourth hollow portion ranges from 0.1 μm to 0.5 μm.

[0013] Furthermore, the ratio of the number of the third hollow protruding structures to the number of the hollow protruding structures is less than 20%; wherein the ratio of the sum of the areas of the hollow parts in the third hollow protruding structures to the area of ​​the slices is in the range of 20%-30%.

[0014] Furthermore, the thickness of the resistance layer ranges from 50 nm to 3 μm.

[0015] Furthermore, the roughness Rz of the conductive layer on the side close to the resistance layer is in the range of 1-7 μm.

[0016] Furthermore, the composite metal foil further includes: an adjustment layer; the adjustment layer is arranged on a side of the resistance layer away from the conductive layer.

[0017] 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%.

[0018] 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%.

[0019] 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.

[0020] 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.

[0021] The composite metal foil provided by the embodiment of the present invention limits the proportion of the hollowed-out parts in the hollowed-out convex structure by setting the ratio of the total area of ​​the hollowed-out parts to the slice area to be less than 20%, accounting for more than 50% of the total number of convex structures in the preset area, thereby improving the solidity of the convex structure, improving the stability of the convex structure, reducing the probability of the convex structure breaking and falling off during the high-temperature and high-pressure pressing process, effectively avoiding the occurrence of holes and cracks in the resistor layer at the position of the hollowed-out parts, and being conducive to improving the continuity of the resistor layer. At the same time, the hollowed-out parts with a lower proportion are connected to the outside world, which can reduce the infiltration of the medicament into the hollowed-out parts when the medicament is soaked in the etched circuit, avoiding the excessive etching of the conductive layer to affect the quality of the line width and the bonding force between the composite metal foil and the substrate, reducing or even avoiding the delamination and falling of the circuit, and improving the reliability of circuit production.

[0022] 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

[0023] 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.

[0024] Figure 1 is a schematic structural diagram of a composite metal foil provided according to an embodiment of the present invention;

[0025] 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;

[0026] Figure 3 is a schematic diagram of a slice structure of a composite metal foil hollow protrusion structure provided according to an embodiment of the present invention;

[0027] Figure 4 Schematic diagram of the structure of another composite metal foil provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] 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 hollow 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, and the resistor layer 10 covers the protrusion structure 201. The protrusion structure 201 includes at least one hollow protrusion structure 202, and the hollow protrusion structure 202 includes at least one hollow portion 2011. The composite metal foil is sliced ​​along a first direction, and within a preset area, the ratio of the number of the first hollow protrusion structures to the number of the protrusion structures 201 is greater than 50%. The first direction is the direction from the conductive layer 20 to the resistor layer 10. In the first hollow protrusion structure, the ratio of the sum of the areas of all the hollow portions 2011 to the slice area of ​​the first hollow protrusion structure is less than 20%.

[0031] Among them, the material of the conductive layer 20 can be metal materials such as copper, gold, silver, iron, aluminum, platinum, cobalt, nickel, manganese, or other non-metallic conductive materials. The embodiment of the present invention does not limit the material of the conductive layer 20, as long as it has good conductivity. The thickness of the conductive layer 20 can also be set according to actual conditions.

[0032] Specifically, the thickness of the conductive layer is 5-100 μm. Exemplarily, the thickness of the conductive layer 20 is 18 μm. For example, the conductive layer 20 is copper foil, and the conductive layer 20 can be made of electrolytic copper foil or rolled copper foil.

[0033] Optionally, the resistance layer 10 can be formed by physical vapor deposition, chemical vapor deposition, evaporation plating, electroplating and mixed plating, and further, the thickness of the resistance layer 10 is 50nm-800nm. The resistance layer 10 can be formed on the first surface of the conductive layer 20 by one or more magnetron sputtering, which is not limited in the embodiment of the present invention.

[0034] The preset area can be understood as a slice area of ​​any size selected after slicing the composite metal foil. The plurality of protrusion structures 201 can be evenly arranged on the surface of the conductive layer 20 close to the resistor layer 10 , or unevenly arranged on the surface of the conductive layer 20 close to the resistor layer 10 .

[0035] Exemplarily, the raised structure 201 is a regular or irregular three-dimensional geometric structure formed in the process of roughening the conductive layer 20. The shape of the raised structure 201 can be one or more of a pointed shape, an inverted cone shape, a granular shape, a dendrite shape, a columnar shape, a block shape, an arc shape, etc., and the embodiment of the present invention is not limited to this.

[0036] Further, at least one can be understood as one or more. Exemplarily, the protrusion structure 201 includes one or more hollow protrusion structures 202, and each hollow protrusion structure 202 includes one or more hollow portions 2011, wherein the hollow portion 2011 is a regular or irregular cavity structure formed in the process of forming the protrusion structure 201.

[0037] The composite metal foil provided by the embodiment of the present invention limits the proportion of the hollowed-out convex structures 202 in the hollowed-out convex structures 202 by setting the ratio of the total area of ​​the hollowed-out parts 2011 to the slice area to be less than 20% to account for more than 50% of the total number of the convex structures 201 in the preset area, thereby improving the solidity of the convex structure 201, improving the stability of the convex structure 201, reducing the probability of the convex structure 201 breaking and falling off during the high-temperature and high-pressure pressing process, effectively avoiding the occurrence of holes and cracks in the resistor layer 10 at the position of the hollowed-out parts 2011, and being conducive to improving the continuity of the resistor layer 10. At the same time, the hollowed-out parts 2011 with a relatively low proportion are connected to the outside world, which can reduce the infiltration of the medicament into the hollowed-out parts 2011 when the medicament is soaked in the etched circuit, avoiding the excessive etching of the conductive layer 20 affecting the quality of the line width and the bonding force between the composite metal foil and the substrate, reducing or even avoiding the delamination and falling off of the circuit, and improving the reliability of the circuit production.

[0038] Optionally, in the slicing state, the hollow portion 2011 may be disposed in a closed manner in the hollow protruding structure 202, or may be disposed at the edge of the hollow protruding structure 202 and communicated with the outside.

[0039] For further reference, Figure 1-Figure 3 The hollow portion 2011 includes a first hollow portion 01 and a second hollow portion 02. The first hollow portion 01 is connected to the outside, and the second hollow portion 02 is located inside the hollow protrusion structure 202.

[0040] Specifically, by reducing the number of the first hollow portions 01, holes and cracks can be effectively avoided in the resistor layer 10 at the positions of the first hollow portions 01 during the manufacturing process of the resistor layer 10, thereby improving the continuity of the resistor layer 10; and when soaking and etching the circuit at the conductive layer 20, by reducing the number of the first hollow portions 01, the infiltration of the chemical solution can be reduced, thereby preventing the conductive layer 20 from being excessively etched and affecting the line width and bonding force, thereby effectively preventing the conductive layer 20 from being delaminated from the substrate and the circuit on the conductive layer 20 from falling off. By reducing the first hollow portions 01 and the second hollow portions 02, the solidity of the protruding structure 201 is improved, the stability of the protruding structure 201 is improved, and the probability of the protruding structure 201 breaking and falling off during the high temperature and high pressure pressing process is reduced.

[0041] For further information, please refer to Figure 1-Figure 3 In one embodiment, the ratio of the number of the second hollow protruding structures to the number of the protruding structures is greater than 50%. The number of the first hollow portions 01 in the second hollow protruding structures is less than the number of the second hollow portions 02.

[0042] Specifically, the number of the hollowed-out protrusions 202 in which the number of the first hollowed-out parts 01 is less than the number of the second hollowed-out parts 02 accounts for more than 50% of the total number of the protrusions 201, so that the number of the first hollowed-out parts 01 on the hollowed-out protrusions 202 is smaller, and thus in the process of manufacturing and forming the resistor layer 10, it is possible to effectively avoid holes and cracks in the resistor layer 10 at the position of the first hollowed-out parts 01, thereby improving the continuity of the resistor layer 10. At the same time, when the composite metal foil is pressed onto the substrate and the lines are immersed and etched at the conductive layer 20, the number of the first hollowed-out parts 01 is reduced, so that the infiltration of the liquid medicine can be reduced, thereby avoiding the conductive layer 20 from being excessively etched and affecting the line width and bonding force, thereby effectively avoiding the delamination of the conductive layer 20 from the substrate and the falling off of the lines on the conductive layer 20.

[0043] Furthermore, in the first hollow protrusion structure, the maximum length of the hollow portion is less than 4.4 μm.

[0044] Specifically, in the first hollow protrusion structure, the maximum length of the hollow portion is set to be less than 4.4 μm, which can avoid the first hollow protrusion structure from breaking and falling off during the high temperature and high pressure pressing process due to the excessive length of the hollow portion in the first hollow protrusion structure, thereby improving the stability of the first hollow protrusion structure. Among them, in the first hollow protrusion structure, the maximum length of the hollow portion can be obtained by software scanning calculation. For example, a focused ion beam electron microscope device can be used to slice the composite metal foil, and the hollow portion in the hollow protrusion structure can be identified by visual statistical software, and the area, maximum length, minimum circumscribed rectangle, etc. of each hollow portion can be determined according to the shape of the identified hollow portion.

[0045] Furthermore, in the first hollow protrusion structure, the ratio of the number of the third hollow parts to the total number of the hollow parts is greater than 60%; wherein the length-to-width ratio of the minimum circumscribed rectangle of the third hollow part is greater than 3.

[0046] Specifically, if the third hollow portion is located inside the hollow protruding structure, the number of the third hollow portions with a minimum external matrix aspect ratio greater than 3 is set to account for more than 60% of the total number of hollow portions, which can avoid the appearance of a large hollow portion inside the first hollow protruding structure, thereby effectively avoiding the possibility of the first hollow protruding structure breaking and falling off during the high temperature and high pressure pressing process, thereby improving the stability of the first hollow protruding structure. If the third hollow portion is connected to the outside world, the number of the third hollow portions with a minimum external matrix aspect ratio greater than 3 is set to account for more than 60% of the total number of hollow portions, thereby avoiding the hollow portion in the first hollow protruding structure from being exposed to the outside world too much, thereby further avoiding the appearance of holes and cracks in the resistor layer at the position of the third hollow portion during the process of making the resistor layer, thereby improving the continuity of the resistor layer; and when the conductive layer is immersed in the etching circuit, by reducing the exposure of the third hollow portion to the outside world, the infiltration of the liquid medicine can be effectively reduced, thereby avoiding the conductive layer from being excessively etched and thus affecting the line width and bonding force, thereby effectively avoiding the delamination of the conductive layer and the substrate and the falling off of the circuit on the conductive layer. Exemplarily, if in the first hollow protruding structure, the ratio of the number of third hollow portions to the total number of hollow portions is less than or equal to 60%, it means that the number of hollow portions with a larger internal range within the first hollow protruding structure is relatively large, and it is easy to break and fall off during the high-temperature and high-pressure pressing process. The hollow portions connected to the outside world are prone to excessive infiltration of chemicals when the conductive layer is immersed in etching circuits, thereby causing the conductive layer to be over-etched and affecting the line width and bonding strength.

[0047] Furthermore, in the first hollow protrusion structure, the ratio of the sum of the areas of the fourth hollow portions to the total area of ​​the hollow portions is greater than 30%; wherein the maximum length of the fourth hollow portion ranges from 0.1 μm to 0.5 μm.

[0048] Specifically, in the first hollow protrusion structure, the ratio of the area of ​​the fourth hollow portion with a maximum length in the range of 0.1μm-0.5μm to the total area of ​​the hollow portion is greater than 30%, thereby increasing the proportion of the smaller-sized fourth hollow portions, effectively improving the solidity of the protrusion structure, reducing the probability of breakage and falling off of the hollow protrusion structure during the high-temperature and high-pressure pressing process, and improving the stability of the hollow protrusion structure.

[0049] Furthermore, the ratio of the number of the third hollow protrusion structures to the number of the hollow protrusion structures is less than 20%; wherein the ratio of the sum of the areas of the hollow parts in the third hollow protrusion structures to the slice area is within a second preset range, and the second preset range is 20%-30%.

[0050] Specifically, the ratio of the number of third hollow protruding structures in which the ratio of the total area of ​​the hollow parts to the slice area is 20%-30% to the number of hollow protruding structures is less than 20%, which can effectively reduce the proportion of the third hollow protruding structures in which the hollow parts account for a relatively large proportion in the hollow protruding structures, improve the solidity of the protruding structures, reduce the probability of breakage and falling off of the hollow protruding structures during the high temperature and high pressure pressing process, and improve the stability of the hollow protruding structures.

[0051] Furthermore, the thickness of the resistance layer ranges from 50 nm to 3 μm.

[0052] Specifically, the resistance layer is set to have a relatively thin thickness. After the composite metal foil is made 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. In addition, compared with the commonly used thermistors and chip resistors, the resistance layer is directly located in the circuit below the heat source, and the heat is conducted through the pad or copper wire, which is more efficient than air heat conduction, so the response rate is higher, which is conducive to improving the accuracy of thermal management.

[0053] Furthermore, the roughness Rz of the conductive layer on the side close to the resistance layer is in the range of 1-7 μm.

[0054] The roughness Rz is used to characterize the microscopic roughness of the surface of the conductive layer.

[0055] 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 1-7μm, which can reduce the height difference of the protruding structure in the conductive layer, thereby effectively improving the bonding strength between the composite metal foil and the substrate, thereby making the bonding between the composite metal foil and the substrate tighter.

[0056] 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 ; the adjustment layer 30 is arranged on a side of the resistance layer 10 away from the conductive layer 20 .

[0057] 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.

[0058] Optionally, the material of the adjustment layer 30 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 conducive to ensuring the bonding force between the resistor layer 10 and the substrate and preventing the circuit from falling off.

[0059] 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%.

[0060] 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.

[0061] 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%.

[0062] The term "at least once" may be understood as one or more than one time. The resistance recovery deviation may be understood as the ratio of the difference between the resistance value of the resistor layer before the temperature rise and the resistance value after one temperature cycle to the resistance value of the resistor layer before the temperature rise.

[0063] 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.

[0064] Experimental Group 1

[0065] A composite metal foil includes 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 610 nm thick. Under electron microscope observation, the ratio of the number of first hollow protrusion structures to the number of protrusion structures is 65%, wherein the ratio of the total area of ​​the hollow parts of all the first hollow protrusion structures to the slice area of ​​the first hollow protrusion structure is less than 20%.

[0066] Experimental Group 2

[0067] On the basis of test group 1, under the observation of scanning electron microscope, the ratio of the number of second hollow protrusion structures to the number of protrusion structures was set to 60%, wherein the number of first hollow parts in all second hollow protrusion structures was less than the number of second hollow parts.

[0068] Experimental Group 3

[0069] Different from the experimental group 1, under the observation of scanning electron microscope, in the first hollow protrusion structure, the maximum length of the hollow part is less than 4.4 μm.

[0070] Control group 1

[0071] The 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 ferrite, and the resistive layer is 1.5 μm thick. Under observation by a scanning electron microscope, the ratio of the number of first hollow protruding structures to the number of protruding structures is 46%, wherein the ratio of the sum of the areas of all the hollow portions in all the first hollow protruding structures to the slice area of ​​the first hollow protruding structures is less than 20%.

[0072] Control group 2

[0073] The composite metal foil includes a conductive layer and a resistive layer, wherein the conductive layer is made of Cu, the thickness of the base layer is 18 μm, the resistive layer is made of Ni-P alloy, and the thickness of the resistive layer is 2.5 nm. Under the observation environment of a scanning electron microscope, the ratio of the number of first hollow protrusion structures to the number of protrusion structures is 13%, wherein the ratio of the sum of the areas of all hollow parts in all first hollow protrusion structures to the slice area of ​​the first hollow protrusion structure is less than 20%. The composite metal foils of the above test group and control group are used to make samples, which are pressed on a semi-cured core layer at 185°C for 10 minutes, and the copper layer is removed with an alkaline etching solution. After cleaning, the samples are placed in a 105°C oven and baked for 10 minutes to remove moisture; small grids of 2 cm×2 cm are marked on the surface of the sample after alkaline etching to remove copper, and the square resistance of each grid is tested with a square resistance meter, and the square resistance uniformity is statistically measured to form a square resistance uniformity comparison table of different test groups and control groups as shown in Table 1.

[0074] Table 1. Comparison of square resistance uniformity of different test groups and control groups

[0075]

[0076] It can be seen from the data in Table 1 that the composite metal foils of test groups 1-3 can have higher square resistance uniformity, which is beneficial to improving the quality of use.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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 protrusion structures, wherein the protrusion structures include at least one hollow protrusion structure, and the hollow protrusion structure includes at least one hollow portion; the composite metal foil is sliced ​​along a first direction, and within a preset area, the ratio of the number of the first hollow protrusion structures to the number of the protrusion structures is greater than 50%; wherein the first direction is the direction in which the conductive layer points to the resistor layer, and the ratio of the total area of ​​the hollow portions in the first hollow protrusion structure to the slice area is less than 20%.

2. The composite metal foil according to claim 1, characterized in that: The hollow portion includes a first hollow portion and a second hollow portion; The first hollow portion is communicated with the outside, and the second hollow portion is located inside the hollow protruding structure.

3. The composite metal foil according to claim 2, characterized in that: The ratio of the number of the second hollow protruding structures to the number of the protruding structures is greater than 50%; wherein the number of the first hollow parts in the second hollow protruding structure is less than the number of the second hollow parts.

4. The composite metal foil according to claim 1, characterized in that: In the first hollow protrusion structure, the maximum length of the hollow portion is less than 4.4 μm.

5. The composite metal foil according to claim 1, characterized in that: In the first hollow protrusion structure, the ratio of the number of third hollow parts to the total number of the hollow parts is greater than 60%; wherein the length-to-width ratio of the minimum circumscribed rectangle of the third hollow part is greater than 3.

6. The composite metal foil according to claim 1, characterized in that: In the first hollow protrusion structure, the ratio of the sum of the areas of the fourth hollow portions to the total area of ​​the hollow portions is greater than 30%; wherein the maximum length of the fourth hollow portion ranges from 0.1 μm to 0.5 μm.

7. The composite metal foil according to claim 1, characterized in that: The ratio of the number of the third hollow protruding structures to the number of the hollow protruding structures is less than 20%; wherein the ratio of the sum of the areas of the hollow parts in the third hollow protruding structures to the area of ​​the slices is in the range of 20%-30%.

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 conductive layer on a side close to the resistance layer is in the range of 1-7 μm.

10. The composite metal foil according to claim 7, characterized in that: Also includes: Adjustment layer; The adjustment layer 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. After at least one temperature cycle, the resistance value recovery deviation of the resistor layer is less than 10%.

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.

Images