Composite metal foil and circuit board

Abstract

The application discloses a composite metal foil and a circuit board. The composite metal foil comprises a dielectric layer, a first resistance layer and a first conductive layer. The first resistance layer is arranged on one side of the dielectric layer. At least part of the area on the side of the dielectric layer close to the first resistance layer is provided with a first protruding structure. The at least part of the area on the side of the first resistance layer close to the dielectric layer and the at least part of the area on the side of the first resistance layer away from the dielectric layer are both provided with a second protruding structure. The first conductive layer is arranged on the side of the first resistance layer away from the dielectric layer. The second protruding structure increases the cross-sectional area of the first resistance layer, improves the current-carrying capacity of the first resistance layer, and further improves the ESD resistance of the first resistance layer, thereby improving the anti-static breakdown capacity of the embedded resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite metal foil, and in particular to a composite metal foil and a circuit board. BACKGROUND

[0002] With the rapid development of wireless communication and electronic devices, electronic devices are evolving towards precision, miniaturization and lightness, and therefore, the size of components inside electronic devices is required to develop towards miniaturization and lightness as much as possible.

[0003] Resistive elements inside electronic devices gradually develop towards lightness from the previous pin-plugged resistors, to the surface mount resistors, to the embedded resistors. The preparation process of the embedded resistors is roughly as follows: the composite metal foil is attached to the circuit board, and the embedded resistors are etched out through an etching process.

[0004] The embedded resistors are integrated with numerous embedded resistors on the circuit board in the terminal electronic product, and the circuit is quite sensitive to electrostatic high voltage. When a person or object with static electricity contacts the embedded resistors, static discharge occurs, and when the electrostatic high voltage impacts the circuit, the embedded resistors are easily broken down by the electrostatic high voltage, thereby causing the embedded resistors to fail. SUMMARY

[0005] An object of the present application is to provide a composite metal foil, which can improve the current-carrying capacity of the first resistive layer, thereby improving the ESD (Electro-Static Discharge) performance of the first resistive layer, and further improving the anti-static breakdown capability of the embedded resistors.

[0006] Another object of the present application is to provide a circuit board prepared from the composite metal foil provided by the present application.

[0007] Still another object of the present application is to provide a circuit board comprising the composite metal foil provided by the present application.

[0008] To achieve the above objects, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a composite metal foil, comprising: a dielectric layer, a first resistive layer and a first conductive layer.

[0010] The first resistive layer is arranged on one side of the dielectric layer.

[0011] At least part of the area on the side of the dielectric layer close to the first resistive layer is provided with a first protruding structure, so that at least part of the area on the side of the first resistive layer close to the dielectric layer and on the side of the first resistive layer away from the dielectric layer forms a second protruding structure.

[0012] The first conductive layer is arranged on a side of the first resistive layer away from the dielectric layer.

[0013] Optionally, at least a part of the dielectric layer on a side away from the first resistive layer is provided with a first protruding structure.

[0014] Optionally, at least a part of the dielectric layer is provided with a filler, so that at least a part of the dielectric layer on both sides has a first protruding structure.

[0015] Optionally, the roughness Rz of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is in a range of 0.1 μm-30 μm.

[0016] Optionally, the roughness Sdr of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is greater than or equal to 0.5%.

[0017] Optionally, the whole area of the dielectric layer on a side close to the first resistive layer is provided with a first protruding structure, so that the whole area of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is formed with a second protruding structure.

[0018] Optionally, at least a part of the dielectric layer on a side close to the first resistive layer is provided with a plurality of continuous first protruding structures, so that at least a part of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is formed with a plurality of continuous protruding structures.

[0019] Optionally, the whole area of the dielectric layer on a side close to the first resistive layer is provided with a plurality of continuous first protruding structures, so that the whole area of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is formed with a plurality of continuous protruding structures.

[0020] Optionally, the whole area of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is formed with continuous second protruding structures, so that the first resistive layer is formed with continuous wave structures.

[0021] Optionally, the roughness Rz of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is in a range of 0.1 μm-10 μm, and the roughness Sdr of the first resistive layer on a side close to the dielectric layer and on a side away from the dielectric layer is greater than or equal to 20%.

[0022] Optionally, roughness Rz of the first resistive layer on the side close to the dielectric layer and the side away from the dielectric layer is in the range of 0.1 μm-10 μm, and roughness Sdr of the first resistive layer on the side close to the dielectric layer and the side away from the dielectric layer is greater than or equal to 50%.

[0023] Optionally, roughness Rz of the first resistive layer on the side close to the dielectric layer and the side away from the dielectric layer is in the range of 0.1 μm-10 μm, and roughness Sdr of the first resistive layer on the side close to the dielectric layer and the side away from the dielectric layer is greater than or equal to 200%.

[0024] Optionally, the side of the dielectric layer away from the first resistive layer is provided with a second resistive layer and a second conductive layer, and the second resistive layer is located between the dielectric layer and the second conductive layer.

[0025] Optionally, the material of the first resistive layer includes at least one single metal of nickel, chromium, platinum, palladium and titanium, and / or an alloy of at least two combinations of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus and aluminum.

[0026] Optionally, the first resistive layer is a single-layer structure or at least a two-layer structure.

[0027] In a second aspect, the embodiment of the present application further provides a circuit board comprising the composite metal foil provided by the first aspect of the present application.

[0028] The composite metal foil provided by the embodiment of the present application comprises a dielectric layer, a first resistive layer and a first conductive layer, the first resistive layer is arranged on one side of the dielectric layer, at least part of the area of the side of the dielectric layer close to the first resistive layer is provided with a first protruding structure, so that at least part of the area of the side of the first resistive layer close to the dielectric layer and the side away from the dielectric layer forms a second protruding structure, and the first conductive layer is arranged on the side of the first resistive layer away from the dielectric layer. The existence of the second protruding structure increases the cross-sectional area of the first resistive layer, improves the current-carrying capacity of the first resistive layer, and further improves the ESD performance of the first resistive layer, thereby improving the anti-static breakdown capability of the embedded resistive layer. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application will be further described in detail below according to the drawings and embodiments.

[0030] Figure 1A A structural schematic diagram of a composite metal foil provided by the embodiment of the present application;

[0031] Figure 1B A structural schematic diagram of another composite metal foil provided by the embodiment of the present application;

[0032] Figure 2AAnother structure schematic diagram of the composite metal foil provided by the embodiment of the present application is shown in the figure;

[0033] Figure 2B Another structure schematic diagram of the composite metal foil provided by the embodiment of the present application is shown in the figure;

[0034] Figure 2C Another structure schematic diagram of the composite metal foil provided by the embodiment of the present application is shown in the figure;

[0035] Figure 3 Another structure schematic diagram of the composite metal foil provided by the embodiment of the present application is shown in the figure;

[0036] Figure 4A Another structure schematic diagram of the composite metal foil provided by the embodiment of the present application is shown in the figure;

[0037] Figure 4B Another structure schematic diagram of the composite metal foil provided by the embodiment of the present application is shown in the figure;

[0038] Figure 5A A flow chart of the preparation method of the composite metal foil provided by the embodiment of the present application is shown in the figure;

[0039] Figure 5B A schematic diagram of forming the first protruding structure on one side of the medium layer provided by the embodiment of the present application is shown in the figure;

[0040] Figure 5C A schematic diagram of forming the first resistance layer on the medium layer provided by the embodiment of the present application is shown in the figure;

[0041] Figure 5D A schematic diagram of forming the first conductive layer on the first resistance layer provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0042] In order to make the technical problems solved by the present application, the technical solutions adopted and the technical effects reached more clear, the technical solutions of the embodiments of the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the person skilled in the art without any creative work are within the protection scope of the present application.

[0043] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature. In addition, the terms "first", "second" are only used to distinguish in the description, and have no special meaning.

[0045] Figure 1A A structure diagram of a composite metal foil provided for an embodiment of the present application is shown in the figure, Figure 1B Another structure diagram of a composite metal foil provided for an embodiment of the present application is shown in the figure, Figure 1A And Figure 1B As shown in the figure, in the embodiment, the medium layer 110, the first resistance layer 120 and the first conductive layer 130.

[0046] Specifically, the medium layer 110 can be an insulating base layer for carrying the first resistance layer 120. Exemplarily, the material of the medium layer 110 can be polyimide or resin with certain flexibility and buffering effect. At least part of the area of the side of the medium layer 110 close to the first resistance layer 120 is provided with a first protruding structure 111, so that the medium layer 110 has a concave-convex surface.

[0047] The first resistance layer 120 is a key functional layer of the composite metal foil, which is used to realize the resistance function of the embedded resistance. Generally, the resistance 120 can be selected from different materials according to the needs of different functions, thereby having different resistance characteristics.

[0048] The material of the first resistance layer 120 can include any one of nickel, chromium, platinum, palladium, titanium, and / or an alloy including at least two of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. For example, a nickel-chromium alloy (NiCr) or a nickel-phosphorus alloy (NiP) having a low resistivity, or a chromium-silicon alloy (CrSi) having a high resistivity, is not limited in the embodiments of the present application. The first resistance layer 120 is a precursor of the first resistance layer in the embedded resistance, in other words, the first resistance layer in the embedded resistance is obtained by removing part of the first resistance layer 120 by etching or the like. The thickness of the first resistance layer 120 ranges from 0.01 μm to 0.5 μm. It should be noted that the high resistivity and the low resistivity in the embodiments of the present application are for the first resistance layer itself, not for the first conductive layer.

[0049] In some embodiments of the present application, the first resistance layer 120 is a single-layer structure or an at least two-layer structure. For example, the single-layer structure can be composed of any one of nickel, chromium, platinum, palladium, and titanium, or an alloy including at least two of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. Any one of the at least two layers can be composed of any one of nickel, chromium, platinum, palladium, and titanium, or an alloy including at least two of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. The thickness of the first resistance layer 120 ranges from 0.01 μm to 0.5 μm.

[0050] The first conductive layer 130 has good conductive performance, and the material of the metal layer can be gold, silver, copper, or aluminum, or an alloy including at least two of them. In other embodiments of the present application, the first conductive layer 130 can also be a non-metal layer having good conductive performance, and the material of the first conductive layer is not limited in the embodiments of the present application as long as it has good conductive performance. The thickness of the first conductive layer 130 ranges from 3 μm to 18 μm.

[0051] The first resistance layer 120 is formed on one side of the dielectric layer 110. Specifically, in one embodiment of the present application, the dielectric layer 110 can be prepared in advance, and then the first resistance layer 120 can be formed on one side of the dielectric layer 110 by physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating, and hybrid plating or the like. Since at least part of the side of the dielectric layer 110 close to the first resistance layer 120 is provided with the first protruding structure 111, the dielectric layer 110 has a concave-convex surface, and thus the first resistance layer 120 formed on the dielectric layer 110 conforms to the protruding structure, so that the two sides of the formed first resistance layer 120 are both provided with the second protruding structure 121.

[0052] The inventor has found that the cross-sectional area of the first resistance layer in the embedded resistance affects the ESD resistance performance. The greater the cross-sectional area of the first resistance layer, the greater the current-carrying capacity of the first resistance layer, and the better the ESD resistance performance. In order to improve the ESD resistance performance of the embedded resistance, the cross-sectional area of the first resistance layer can be increased.

[0053] The embodiment of the present application forms the second protruding structure 121 on at least part of the area on both sides of the first resistance layer 120, so that the first resistance layer 120 has a rough surface. The presence of the second protruding structure 121 increases the cross-sectional area of the first resistance layer 120, improves the current-carrying capacity of the first resistance layer 120, and further improves the ESD resistance performance of the first resistance layer, and further improves the anti-static breakdown performance of the embedded resistance.

[0054] The composite metal foil provided by the embodiment of the present application includes a dielectric layer, a first resistance layer and a first conductive layer. The first resistance layer is arranged on one side of the dielectric layer. At least part of the area on the side of the dielectric layer close to the first resistance layer is provided with a first protruding structure, so that at least part of the area on both sides of the first resistance layer forms a second protruding structure. The first conductive layer is arranged on the side of the first resistance layer away from the dielectric layer. The presence of the second protruding structure increases the cross-sectional area of the first resistance layer, improves the current-carrying capacity of the first resistance layer, and further improves the ESD resistance performance of the first resistance layer, and further improves the anti-static breakdown performance of the embedded resistance.

[0055] In some embodiments of the present application, the roughness Rz of at least part of the area (the area provided with the protruding structure) on both sides of the first resistance layer 120 is greater than or equal to 0.1 μm, and the roughness Sdr is greater than or equal to 0.5%. The roughness Rz and the roughness Sdr are used to characterize the micro-unevenness of the surface of the first resistance layer 120. Specifically, the average of the five largest profile peak heights in the sampling length and the sum of the average of the five largest profile valley depths are taken as the roughness Rz. The roughness Sdr is the expansion area (surface area) of the defined area, which indicates how much the area of the defined area has increased, wherein the roughness Sdr of a completely flat surface is zero. It should be noted that in the embodiments of the present application, the roughness Rz on both sides of the first resistance layer 120 can be the same or different, and the roughness Sdr on both sides of the first resistance layer 120 can be the same or different, which is not limited in the embodiments of the present application. It should be noted that in the embodiments and subsequent embodiments, the test standard of the roughness is ISO25178 standard.

[0056] Further, in some embodiments of the present application, in order to further improve the ESD resistance of the first resistive layer, the roughness Rz of the two sides of the first resistive layer 120 ranges from 0.1 μm to 30 μm, inclusive of 0.1 μm and 30 μm, and the roughness Rz of the two sides of the first resistive layer 120 can also be 1 μm, 5 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, etc. The roughness Sdr ranges from 0.5% to 8000%, inclusive of 0.5% and 8000%, and the roughness Sdr can also be 1%, 5%, 12%, 20%, 50%, 80%, 100%, 200%, 500%, 800%, 1500%, 2000%, 2500%, 3000%, 3500%, 4000%, 4500%, 5000%, 5500%, 6000%, 6500%, 7000%, 7500%, etc.

[0057] Table 1 is the test result of the ESD resistance test of the first resistive layer with different roughness Rz. The test method is as follows: under the condition that other conditions are constant, a forward test static voltage is applied to the first resistive layer with a certain roughness, applied for three times, with an interval of 10 seconds each time, then a reverse test static voltage is applied to the first resistive layer, applied for three times, with an interval of 10 seconds each time. The test static voltage is gradually increased, and the test static voltage that breaks down the first resistive layer is taken as the static discharge resistance voltage of the first resistive layer.

[0058] Table 1

[0059]

[0060]

[0061] As shown in Table 1, different roughness Rz has different static discharge resistance voltage, that is, by setting the protruding structure on at least part of the area of the side of the first resistive layer away from the first conductive layer, adjusting the roughness Rz of the first resistive layer, the static discharge resistance voltage of the first resistive layer can be improved.

[0062] Table 2 is the test result of the ESD resistance test of the first resistive layer with different roughness Sdr. The test method is the same as before.

[0063] Table 2

[0064] Sdr (%) Static discharge voltage resistance (KV) 0.5 0.53 10 0.76 70 1.45 100 2.18 500 3.07 1000 4.11 8000 4.3

[0065] As shown in Table 2, different roughness Sdr has different static discharge resistance voltage, that is, by setting the protruding structure on at least part of the area of the side of the first resistive layer away from the first conductive layer, adjusting the roughness Sdr of the first resistive layer, the static discharge resistance voltage of the first resistive layer can be improved.

[0066] In the embodiments of the present application, the shape of the second protruding structure 121 can be various according to actual needs, and can be regular or irregular three-dimensional geometric shapes, for example, the shape of the second protruding structure 121 can be one or more of sharp corner shape, inverted cone shape, granular shape, branch shape, columnar shape, block shape, and arc shape, which are not limited in the embodiments of the present application.

[0067] In order to further improve the ESD performance (i.e., the static discharge voltage performance) of the first resistance layer 120, the second protruding structure 121 arranged in at least part of the area on both sides of the first resistance layer 120 is arranged continuously. For example, as shown in FIG. 1B, the shape of the second protruding structure 121 is branch shape, and the second protruding structure 121 is continuously distributed on at least part of the area of the first resistance layer 120. Figure 1A Figure 1B For example, as shown in FIG. 1C, the shape of the second protruding structure 121 is arc shape, and the second protruding structure 121 is continuously distributed on at least part of the area of the first resistance layer 120 to form a structure similar to "sine curve" shape on both sides of the first resistance layer 120. In addition, in other embodiments of the present application, the second protruding structure can include a continuous undulating surface formed on both sides of the first resistance layer, and a plurality of protrusions formed on the undulating surface, which are not limited in the embodiments of the present application. In addition, in still other embodiments of the present application, the second protruding structure can also be discontinuously distributed on at least part of the area on both sides of the first resistance layer, which are not limited in the embodiments of the present application.

[0068] In some embodiments of the present application, the material of the medium layer 110 can be resin glue, polyimide (PI), modified polyimide, glass cloth, glass cloth composite material, paper substrate, composite substrate, HDI plate material, modified epoxy resin, modified acrylic resin, polyethylene terephthalate glycol, polybutylene terephthalate, polyethylene, etc., which is used to protect the first resistance layer 120 and avoid the first resistance layer 120 from being damaged by external force.

[0069] In some embodiments of the present application, at least part of the area of the medium layer 110 is provided with fillers, so that at least part of the area on both sides of the medium layer 110 has the first protruding structure 111. The first protruding structure 111 on the surface of the medium layer 110 away from the first resistance layer 120 makes the surface rougher, and after the composite metal foil is attached to the circuit board, the composite metal foil can be attached more closely to the circuit board, avoiding the composite metal foil from being peeled off from the circuit board.

[0070] Figure 2A FIG. 2 shows another structure of a composite metal foil provided by an embodiment of the present application, Figure 2B FIG. 3 shows another structure of a composite metal foil provided by an embodiment of the present application, Figure 2C ​Another structure of the composite metal foil provided by the embodiment of the present application is shown in FIG. 2B. In this embodiment, the composite metal foil comprises a dielectric layer 210, a first resistive layer 220, and a first conductive layer 230. Figure 2A 、 Figure 2B and Figure 2C In this embodiment, the composite metal foil comprises a dielectric layer 210, a first resistive layer 220, and a first conductive layer 230.

[0071] Specifically, the dielectric layer 210 can be an insulating base layer for carrying the first resistive layer 220. The first resistive layer 220 is a key functional layer of the composite metal foil, and is used to realize the resistive function of the composite metal foil. The material of the first resistive layer 220 can include at least one of nickel, chromium, platinum, palladium, and titanium, and / or an alloy comprising at least two of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. For example, a nickel-chromium alloy (NiCr) or a nickel-phosphorus alloy (NiP) with low resistivity, or a chromium-silicon alloy (CrSi) with high resistivity. In a specific embodiment of the present application, the material of the first resistive layer 220 is a nickel-chromium alloy. In some embodiments of the present application, the first resistive layer 220 can be a single-layer structure or a multi-layer structure. For example, the single-layer structure can be composed of any one of nickel, chromium, platinum, palladium, and titanium, or an alloy comprising at least two of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. Any one of the layers in the multi-layer structure can be composed of any one of nickel, chromium, platinum, palladium, and titanium, or an alloy comprising at least two of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. The first conductive layer 230 has good conductivity, and the material of this metal layer can be gold, silver, copper, or aluminum, or an alloy comprising at least two of them.

[0072] The first resistive layer is formed on one side of the dielectric layer, and at least part of the area on the side of the dielectric layer close to the first resistive layer is provided with a first protruding structure. For example, the entire area on the side of the dielectric layer 210 close to the first resistive layer 220 is provided with a first protruding structure 211, so that the dielectric layer 210 has a concave-convex surface, and the two sides of the formed first resistive layer 220 conform to the second protruding structure 221. Since the entire surface on both sides of the first resistive layer 220 is provided with the second protruding structure 221, compared with the case where only part of the area is provided with the second protruding structure 221, the cross-sectional area of the first resistive layer 220 is further increased, and the anti-static breakdown capability of the embedded resistor is improved.

[0073] Specifically, the roughness Rz of the two sides of the first resistance layer 220 is greater than or equal to 0.1 μm, and the roughness Sdr is greater than or equal to 0.5%. It should be noted that in the embodiment of the present application, the roughness Rz of the two sides of the first resistance layer 220 can be the same or different, and the roughness Sdr of the two sides of the first resistance layer 220 can be the same or different, which is not limited in the embodiment of the present application. Preferably, the roughness Rz of the two sides of the first resistance layer 220 is 0.1 μm-30 μm, including 0.1 μm and 30 μm, and the roughness Rz of the two sides of the first resistance layer 220 can also be 1 μm, 5 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, etc. The roughness Sdr is 0.5%-8000%, including 0.5% and 8000%, and the roughness Sdr can also be 1%, 5%, 12%, 20%, 50%, 80%, 100%, 200%, 500%, 800%, 1500%, 2000%, 2500%, 3000%, 3500%, 4000%, 4500%, 5000%, 5500%, 6000%, 6500%, 7000%, 7500%, etc.

[0074] In the embodiment of the present application, the shape of the second protruding structure can be various according to actual needs, which can be regular or irregular three-dimensional geometric shape, which is not limited in the embodiment of the present application. In some examples, the second protruding structure can form a continuous undulating surface on the two sides of the first resistance layer, or can form a relatively regular "sine line" shape on the two sides of the first resistance layer, or the shape of the protruding structure can be one or more of sharp angle, inverted cone, granular, dendritic, columnar, block, arc.

[0075] In the embodiment of the present application, as shown in Figure 2C To further improve the ESD performance of the first resistance layer 220, the second protruding structure 221 arranged on the entire area of the two sides of the first resistance layer 220 is continuously arranged, that is, the second protruding structure 221 is continuously arranged on the two sides of the first resistance layer 220, so as to further increase the cross-sectional area of the first resistance layer 220 and improve the ESD performance of the first resistance layer 220, thereby improving the anti-static breakdown capability of the embedded resistance.

[0076] Further, if the roughness height parameter Rz of the second protruding structure 221 is set too high, the second protruding structure 221 is prone to be broken by external force when applied, and thus the ESD resistance of the first resistance layer 220 is affected. Therefore, the roughness Rz of the first resistance layer 220 is set to be in the range of 0.1 μm to 10 μm, and the roughness Sdr of the first resistance layer 220 is set to be greater than or equal to 20%. By limiting the roughness height parameter Rz of the first resistance layer 220 to be in the range of 0.1 μm to 10 μm and the increase parameter Sdr of the surface area relative to the defined area to be greater than or equal to 20%, the second protruding structure 221 is continuously and closely arranged on the whole area on both sides of the first resistance layer 220 within a certain height range of the second protruding structure 221 (the continuously and closely arranged protruding structure is similar to a "fluff" structure), so that the first resistance layer 220 with a larger cross section is obtained under the condition that the roughness height parameter Rz is constant, that is, the second protruding structure 221 is not broken by external force, and thus the ESD resistance of the first resistance layer 220 is improved, and the embedded resistance has a stronger anti-static breakdown capability.

[0077] Preferably, the roughness Rz of the first resistance layer 220 is in the range of 0.1 μm to 10 μm, and the roughness Sdr of the first resistance layer 220 is greater than or equal to 50%. By limiting the roughness height parameter Rz of the first resistance layer 220 to be in the range of 0.1 μm to 10 μm and the increase parameter Sdr of the surface area relative to the defined area to be greater than or equal to 50%, the second protruding structure 221 is continuously and more closely arranged on the whole area on both sides of the first resistance layer 220 within a certain height range of the second protruding structure 221, that is, the protruding structure is more closely arranged than the roughness Sdr of the range greater than or equal to 20%, so that the cross section of the first resistance layer is further increased, the ESD resistance of the first resistance layer is further improved, and the embedded resistance has a stronger anti-static breakdown capability.

[0078] More preferably, the roughness Rz of the first resistance layer 220 is in the range of 0.1 μm to 10 μm, and the roughness Sdr of the first resistance layer 220 is greater than or equal to 200%, so that the cross section of the first resistance layer is further increased, the ESD resistance of the first resistance layer is further improved, and the embedded resistance has an excellent anti-static breakdown capability.

[0079] The material of the medium layer 210 can be resin glue, polyimide (PI), modified polyimide, glass cloth, glass cloth composite, paper substrate, composite substrate, HDI board, modified epoxy resin, modified acrylic resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc., for protecting the first resistance layer 220 and avoiding damage to the first resistance layer 220 from external forces.

[0080] In some embodiments of the present application, the entire area of the medium layer 210 is provided with fillers, so that the entire area on both sides of the medium layer 210 has the first protruding structure 211. The medium layer 210 is away from the first protruding structure 211 on the first resistance layer 220, so that the surface is rougher, and after the composite metal foil is attached to the circuit board, it can be attached more closely to the circuit board, avoiding peeling of the composite metal foil from the circuit board.

[0081] Figure 3 Another structure of the composite metal foil provided by the embodiments of the present application is shown in FIG. 3. In this embodiment, the composite metal foil includes a medium layer 310, a first resistance layer 320, and a first conductive layer 330. Figure 3

[0082] Specifically, the medium layer 310 can be an insulating base layer for carrying the first resistance layer 320. The first resistance layer 320 is a key functional layer of the composite metal foil, for realizing the resistance function of the composite metal foil. The material of the first resistance layer 320 can include at least one single metal of nickel, chromium, platinum, palladium, titanium, and / or an alloy including at least two combinations of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. For example, nickel-chromium alloy (NiCr) or nickel-phosphorus alloy (NiP) with low resistivity, or chromium-silicon alloy (CrSi) with high resistivity. In a specific embodiment of the present application, the material of the first resistance layer 320 is nickel-chromium alloy. In some embodiments of the present application, the first resistance layer 320 can be a single-layer structure or at least a two-layer structure. For example, the single-layer structure can be a single-layer structure composed of any one of nickel, chromium, platinum, palladium, and titanium, or a single-layer structure composed of an alloy of at least two combinations of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. Any one of the at least two layers can be a single metal composed of any one of nickel, chromium, platinum, palladium, and titanium, or an alloy of at least two combinations of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, and aluminum. The first conductive layer 330 has good conductivity, and the material of the metal layer can be gold, silver, copper, or aluminum, or an alloy of at least two of them.

[0083] ​The first resistance layer is formed on one side of the dielectric layer, and the whole area of the side of the dielectric layer close to the first resistance layer is provided with the first protruding structure. For example, the whole area of the side of the dielectric layer 310 close to the first resistance layer 320 is provided with the continuous first protruding structure 311, so that the dielectric layer 310 has a continuous wavy surface, and the whole area of the two sides of the formed first resistance layer 320 is provided with the continuous second protruding structure 321, so that the first resistance layer 320 has a continuous wavy structure.

[0084] Specifically, the roughness Rz of the two sides of the first resistance layer 320 is greater than or equal to 0.1 μm, and the roughness Sdr is greater than or equal to 0.5%. It should be noted that in the embodiments of the present application, the roughness Rz of the two sides of the first resistance layer 320 can be the same or different, and the roughness Sdr of the two sides of the first resistance layer 320 can be the same or different, which is not limited in the embodiments of the present application. Preferably, the roughness Rz of the two sides of the first resistance layer 320 is 0.1 μm-30 μm, including 0.1 μm and 30 μm, and the roughness Rz of the two sides of the first resistance layer 320 can also be 1 μm, 5 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, etc. The roughness Sdr is 0.5%-8000%, including 0.5% and 8000%, and the roughness Sdr can also be 1%, 5%, 12%, 20%, 50%, 80%, 100%, 200%, 500%, 800%, 1500%, 2000%, 2500%, 3000%, 3500%, 4000%, 4500%, 5000%, 5500%, 6000%, 6500%, 7000%, 7500%, etc.

[0085] The material of the dielectric layer 310 can be resin glue, polyimide (PI), modified polyimide, glass cloth, glass cloth composite material, paper substrate, composite substrate, HDI board material, modified epoxy resin, modified acrylic resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc., which is used to protect the first resistance layer 320 and avoid damage to the first resistance layer 320 from external force.

[0086] In some embodiments of the present application, the whole area of the dielectric layer 310 is provided with the filler, so that the whole area of the two sides of the dielectric layer 310 has the first protruding structure 311. The first protruding structure 311 on the dielectric layer 310 away from the first resistance layer 320 makes the surface rougher, and after the composite metal foil is attached to the circuit board, it can be attached more closely to the circuit board, avoiding peeling of the composite metal foil from the circuit board.

[0087] Furthermore, a second resistive layer and a second conductive layer are disposed on the side of the dielectric layer away from the first resistive layer, with the second resistive layer located between the dielectric layer and the second conductive layer. The materials and uses of the second resistive layer and the first resistive layer can be the same or different; similarly, the materials and uses of the second conductive layer and the first conductive layer can be the same or different. In addition, the structure and parameters of the second resistive layer can be the same as those of the first resistive layer, and the structure and parameters of the second conductive layer can also be the same as those of the first conductive layer; these will not be elaborated further here.

[0088] Figure 4A This is a schematic diagram of another composite metal foil provided in an embodiment of the present invention. Figure 4B A schematic diagram of another composite metal foil provided in an embodiment of the present invention is shown below. Figure 4A and Figure 4B As shown, the composite metal foil includes a dielectric layer 410, a first resistive layer 420, a first conductive layer 430, a second resistive layer 440, and a second conductive layer 450. The first resistive layer 420 is formed on one side of the dielectric layer 410. A first protrusion structure 411 is provided on the entire area of ​​the dielectric layer 410 near the first resistive layer 420, giving the dielectric layer 410 an uneven surface. Second protrusion structures 421 are formed on both sides of the formed first resistive layer 420 in accordance with this. The materials of the first conductive layer, the first resistive layer, and the dielectric layer, the shape of the second protrusion structure, and the roughness of both sides of the first resistive layer have been described in detail in the foregoing embodiments, and will not be repeated here.

[0089] The second resistive layer 440 is disposed on the side of the dielectric layer 410 away from the first resistive layer 420, and the second conductive layer 450 is disposed on the side of the second resistive layer 440 away from the dielectric layer 410. In a specific embodiment of the present invention, the second resistive layer 420 and the first resistive layer 440 are made of the same material and have the same purpose; similarly, the second conductive layer 450 and the first conductive layer 410 are made of the same material and have the same purpose.

[0090] One or both sides of the second resistive layer 440 can be flat surfaces, or, similar to the first resistive layer 420, at least a portion of it can have raised structures. For example, as shown... Figure 4A As shown, the second resistive layer 440 has a raised structure on the side away from the dielectric layer 410; for example... Figure 4B As shown, the entire area on both sides of the second resistive layer 440 is provided with a protruding structure. The protruding structure can refer to the protruding structure on the first resistive layer 420 described in the foregoing embodiment of the present invention. The embodiment of the present invention will not be described again here.

[0091] Figure 5A A flowchart illustrating a method for preparing a composite metal foil according to an embodiment of the present invention is shown below. Figure 5A As shown, the method includes:

[0092] S501, a medium layer is provided.

[0093] Specifically, the medium layer can be resin glue, polyimide (PI), modified polyimide, glass cloth, glass cloth composite material, paper substrate, composite substrate, HDI plate material, modified epoxy resin, modified acrylic resin, polyethylene terephthalate glycol, polybutylene terephthalate, polyethylene, etc.

[0094] S502, a first protruding structure is formed on at least part of the area on one side of the medium layer.

[0095] Specifically, the first protruding structure can be formed on at least part of the area on one side of the medium layer by physical polishing, chemical etching, shot blasting, sand blasting, etc. Figure 5B A schematic diagram of forming a first protruding structure on one side of a medium layer provided by an embodiment of the present application is shown in FIG. 5A. Figure 5B As shown in FIG. 5A, the first protruding structure 511 is formed on the entire area on one side of the medium layer 510. The shape of the first protruding structure can have diversity according to actual needs, which can be regular or irregular three-dimensional geometric shape, which is not limited in the embodiment of the present application.

[0096] Specifically, in another embodiment of the present application, filler can be provided on the entire area of the medium layer 510, so that the entire area on both sides of the medium layer 510 has the first protruding structure 511. The medium layer 510 is away from the first protruding structure 511 on the first resistance layer 520, so that the surface is rougher. When the composite metal foil is attached to the circuit board, it can be attached more closely to the circuit board, avoiding the separation of the composite metal foil and the circuit board.

[0097] S503, a first resistance layer is formed on the side of the medium layer with the first protruding structure.

[0098] Specifically, the first resistance layer can be formed on the side of the medium layer with the first protruding structure by physical vapor deposition, chemical vapor deposition, evaporation plating, sputtering plating, electroplating and hybrid plating, etc. The first resistance layer is a key functional layer of the composite metal foil, which is used to realize the resistance function of the composite metal foil. The material of the first resistance layer can include at least one of nickel, chromium, platinum, palladium, titanium, and / or at least two combinations of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, aluminum. For example, nickel-chromium alloy (NiCr) or nickel-phosphorus alloy (NiP) with low resistivity, or chromium-silicon alloy (CrSi) with high resistivity, which is not limited in the embodiment of the present application. In some embodiments of the present application, the first resistance layer can be a single-layer structure or at least a two-layer structure. Any layer can be any one of nickel, chromium, platinum, palladium, titanium to form a single metal, or at least two combinations of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus, aluminum to form an alloy.

[0099] Figure 5C This is a schematic diagram of forming a first resistive layer on a dielectric layer according to an embodiment of the present invention, as shown below. Figure 5C As shown, a first resistive layer 520 is formed on the side of the dielectric layer 510 where the first protrusion structure 511 is formed. Since the first protrusion structure 511 is formed over the entire area of ​​one side of the dielectric layer 510, second protrusion structures 521 are formed on both sides of the first resistive layer formed on that side. The shape of the second protrusion structure can be diverse according to actual needs, and can be a regular or irregular three-dimensional geometric shape. This embodiment of the invention does not limit this. In some examples, the second protrusion structure can form a continuous undulating surface on both sides of the first resistive layer, or it can form a relatively regular sinusoidal shape on both sides of the first resistive layer, or the shape of the second protrusion structure can be one or more of the following: pointed, inverted conical, granular, dendritic, columnar, blocky, arc-shaped, or the second protrusion structure can make the first resistive layer form a continuous wavy undulating structure.

[0100] Specifically, the roughness Rz on both sides of the first resistive layer 520 is greater than or equal to 0.1 μm, and the roughness Sdr is greater than or equal to 0.5%. It should be noted that in this embodiment of the invention, the roughness Rz on both sides of the first resistive layer 420 may be the same or different, and the roughness Sdr on both sides of the first resistive layer 420 may be the same or different; this embodiment of the invention does not impose any limitations on this. Preferably, the roughness Rz on both sides of the first resistive layer 520 ranges from 0.1 μm to 30 μm, including 0.1 μm and 30 μm, and the roughness Rz value on both sides of the first resistive layer 520 may also be 1 μm, 5 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, etc. The roughness Sdr ranges from 0.5% to 8000%, including 0.5% and 8000%, and the roughness Sdr value can also be 1%, 5%, 12%, 20%, 50%, 80%, 100%, 200%, 500%, 800%, 1500%, 2000%, 2500%, 3000%, 3500%, 4000%, 4500%, 5000%, 5500%, 6000%, 6500%, 7000%, 7500%, etc.

[0101] S504. A first conductive layer is formed on the side of the first resistive layer away from the dielectric layer.

[0102] Specifically, the first conductive layer can be formed on the side of the first resistive layer away from the dielectric layer by means of physical vapor deposition, chemical vapor deposition, evaporation deposition, sputtering deposition, electroplating, and hybrid deposition. The first conductive layer can have good conductivity, and the material of the metal layer can be gold, silver, copper, or aluminum, or an alloy of at least two of these.

[0103] Figure 5D As shown in the schematic diagram of forming the first conductive layer on the first resistive layer provided by the embodiment of the present application, Figure 5D The first conductive layer 530 is formed on the side of the first resistive layer 520 away from the dielectric layer 510.

[0104] Further, the second resistive layer and the second conductive layer are arranged on the side of the dielectric layer away from the first resistive layer, and the second resistive layer is arranged between the dielectric layer and the second conductive layer. The materials and purposes of the second resistive layer and the first resistive layer can be the same or different, and the materials and purposes of the second conductive layer and the first conductive layer can be the same or different.

[0105] The preparation method of the composite metal foil provided by the embodiment of the present application comprises the following steps: providing a dielectric layer, forming a first protruding structure on at least part of the side of the dielectric layer, forming a first resistive layer on the side of the dielectric layer on which the first protruding structure is formed, and forming a first conductive layer on the side of the first resistive layer away from the dielectric layer. Through the above method, a plurality of second protruding structures are formed on both sides of the first resistive layer. The existence of the second protruding structures increases the cross-sectional area of the first resistive layer, improves the current-carrying capacity and ESD resistance of the first resistive layer, and further improves the product performance of the embedded resistors.

[0106] The embodiment of the present application also provides a circuit board comprising the composite metal foil provided by any of the above embodiments of the present application.

[0107] The circuit board provided by the embodiment of the present application has corresponding functions and beneficial effects of the composite metal foil provided by the embodiment of the present application.

[0108] In the description herein, it should be understood that the terms “upper”, “lower”, “left”, “right”, and the like, orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0109] In the description of the present specification, the description referring to the terms “an embodiment”, “an example”, and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0110] In addition, it should be understood that although the present specification describes the embodiments in a specific manner, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

[0111] The technical principles of the present application are described above in combination with specific embodiments. These descriptions are only for the purpose of explaining the principles of the present application and cannot be interpreted in any way as a limitation on the scope of protection of the present application. Based on the explanations here, those skilled in the art can think of other specific embodiments of the present application without having to exert creative labor, and these ways will fall within the scope of protection of the present application.

Claims

1. A composite metal foil, characterized by, Comprising: a medium layer, a first resistance layer, and a first conductive layer; the first resistance layer is disposed on one side of the medium layer; at least a part of the medium layer on the side close to the first resistance layer is provided with a first protruding structure, and the first resistance layer is formed on the side of the medium layer provided with the first protruding structure, so that at least a part of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer are both provided with a second protruding structure; the first conductive layer is disposed on the side of the first resistance layer away from the medium layer; the roughness Rz of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from 0.1 μm to 30 μm; the roughness Sdr of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from greater than or equal to 0.5%.

2. The composite metal foil according to claim 1, wherein at least a part of the side of the medium layer away from the first resistance layer is provided with a first protruding structure.

3. The composite metal foil according to claim 1, wherein at least a part of the medium layer is provided with a filler, so that at least a part of the two sides of the medium layer is provided with a first protruding structure.

4. The composite metal foil according to claim 1, wherein the whole side of the medium layer close to the first resistance layer is provided with a first protruding structure, so that the whole side of the first resistance layer close to the medium layer and the whole side of the first resistance layer away from the medium layer are both provided with a second protruding structure.

5. The composite metal foil according to claim 1, wherein at least a part of the side of the medium layer close to the first resistance layer is provided with a plurality of continuous first protruding structures, so that at least a part of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer are both provided with a plurality of continuous protruding structures.

6. The composite metal foil according to claim 5, wherein the whole side of the medium layer close to the first resistance layer is provided with a plurality of continuous first protruding structures, so that the whole side of the first resistance layer close to the medium layer and the whole side of the first resistance layer away from the medium layer are both provided with a plurality of continuous protruding structures.

7. The composite metal foil according to claim 5, wherein the whole side of the first resistance layer close to the medium layer and the whole side of the first resistance layer away from the medium layer are both provided with continuous second protruding structures, so that the first resistance layer forms a continuous wave structure.

8. The composite metal foil according to any one of claims 1 to 7, wherein the roughness Rz of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from 0.1 μm to 10 μm, and the roughness Sdr of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from greater than or equal to 20%.

9. The composite metal foil according to any one of claims 1 to 7, wherein the roughness Rz of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from 0.1 μm to 10 μm, and the roughness Sdr of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from greater than or equal to 50%.

10. The composite metal foil according to any one of claims 1 to 7, wherein the roughness Rz of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from 0.1 μm to 10 μm, and the roughness Sdr of the side of the first resistance layer close to the medium layer and the side of the first resistance layer away from the medium layer both ranges from greater than or equal to 200%.

11. The composite metal foil according to any one of claims 1 to 7, wherein The second resistance layer is located between the dielectric layer and the second conductive layer.

12. The composite metal foil according to any one of claims 1 to 7, wherein The material of the first resistance layer comprises at least one single metal of nickel, chromium, platinum, palladium and titanium, and / or an alloy of at least two of nickel, chromium, platinum, palladium, titanium, silicon, phosphorus and aluminum.

13. The composite metal foil of claim 12, wherein, The first resistance layer is a single-layer structure or at least a two-layer structure.

14. A wiring board, characterized by comprising: The composite metal foil comprises the composite metal foil according to any one of claims 1-13.

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