CN110952117B - Micro-rough electrolytic copper foil and copper foil substrate - Google Patents

Micro-rough electrolytic copper foil and copper foil substrate Download PDF

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CN110952117B
CN110952117B CN201811132277.4A CN201811132277A CN110952117B CN 110952117 B CN110952117 B CN 110952117B CN 201811132277 A CN201811132277 A CN 201811132277A CN 110952117 B CN110952117 B CN 110952117B
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micro
copper foil
rough
less
clusters
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CN110952117A (en
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宋云兴
高羣祐
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Jinju Development Co ltd
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Jinju Development Co ltd
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    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00Electroplating: Baths therefor
    • C25D3/02Electroplating: Baths therefor from solutions
    • C25D3/38Electroplating: Baths therefor from solutions of copper
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/18Electroplating using modulated, pulsed or reversing current
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00Electroplating characterised by the article coated
    • C25D7/06Wires; Strips; Foils
    • C25D7/0614Strips or foils
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00Apparatus or processes for manufacturing printed circuits
    • H05K3/38Improvement of the adhesion between the insulating substrate and the metal
    • H05K3/382Improvement of the adhesion between the insulating substrate and the metal by special treatment of the metal

Abstract

The invention discloses a micro-rough electrolytic copper foil and a copper foil substrate. The micro-rough electrolytic copper foil includes a micro-rough surface. The micro-rough surface has a plurality of peaks, a plurality of V-shaped grooves and a plurality of micro-crystal clusters. Two adjacent peaks define a V-shaped groove. The average depth of the V-shaped grooves is less than 1 micron. The micro-crystalline clusters are located at the top of the peaks. The average height of the microcrystalline clusters is less than 1.5 microns. The micro-roughened surface of the micro-roughened electrolytic copper foil has an Rlr value of less than 1.06. The micro-rough surface has good bonding force with the substrate, and insertion loss under high frequency has good performance, so that signal loss can be effectively inhibited.

Description

Micro-rough electrolytic copper foil and copper foil substrate
Technical Field
The present invention relates to a copper foil, and more particularly, to an electrolytic copper foil and a copper clad laminate having the same.
Background
With the development of information and electronics industries, high frequency and high speed signal transmission has become a part of modern circuit design and manufacture. In order to meet the requirement of high-frequency and high-speed signal transmission, the copper foil substrate used in the electronic product needs to have good insertion loss (insertion loss) performance at high frequency so as to prevent excessive loss of high-frequency signals during transmission. The insertion loss of the copper foil substrate is highly correlated with the surface roughness thereof. When the surface roughness is reduced, the insertion loss performs better, otherwise it is not. However, the reduction of the roughness also causes a drop in the peel strength between the copper foil and the substrate, which affects the yield of the rear-end product. Therefore, it is an object of the present invention to provide a method for improving the insertion loss performance while maintaining the peel strength at an industrial level.
Disclosure of Invention
The invention aims to solve the technical problem of providing a micro-rough electrolytic copper foil aiming at the defects of the prior art.
In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a micro-rough electrolytic copper foil. The micro-rough electrolytic copper foil comprises a micro-rough surface. The micro-rough surface is provided with a plurality of convex peaks, a plurality of V-shaped grooves and a plurality of micro-crystal clusters, two adjacent convex peaks define a V-shaped groove, the average depth of the V-shaped groove is less than 1 micrometer, the micro-crystal clusters are positioned at the tops of the convex peaks, and the average height of the micro-crystal clusters is less than 1.5 micrometers. The micro-rough surface of the micro-rough electrolytic copper foil has an Rlr value of less than 1.06.
Preferably, each of said microcrystalline clusters is comprised of a plurality of stacks of microcrystals, said microcrystals having an average diameter of less than 0.5 micron and each of said microcrystalline clusters having an average height of less than 1.3 microns.
Preferably, the average stacking number of the microcrystals of each of the microcrystallization clusters in the height direction thereof is 15 or less; the average maximum width of the microcrystallized clusters is less than 5 microns; part of the microcrystalline clusters form a branched structure.
Preferably, each of said microcrystalline clusters is comprised of a plurality of stacks of microcrystals, said microcrystals having an average diameter of less than 0.5 micron and each of said microcrystalline clusters having an average height of less than 1.3 microns.
Preferably, the micro-roughened surface of the micro-roughened electrolytic copper foil has an Rlr value of less than 1.055.
In order to solve the above technical problems, one of the technical solutions of the present invention is to provide a copper foil substrate, which includes a base material and a micro-rough electrolytic copper foil. The micro-rough electrolytic copper foil comprises a micro-rough surface attached to the base material. The micro-rough surface is formed with a plurality of convex peaks, a plurality of V-shaped grooves and a plurality of micro-crystal clusters. Two adjacent peaks define a V-shaped groove. The average depth of the V-shaped grooves is less than 1 micron. The micro-crystalline clusters are located at the tops of the peaks. The average height of the microcrystalline clusters is less than 1.5 microns. The insertion loss of the copper foil substrate at 20GHz is between 0 and-0.635 db/in. The peel strength between the micro-rough electrolytic copper foil and the base material is more than 3 lb/in.
Preferably, the insertion loss of the copper foil substrate at 30GHz is between 0 and-0.935 db/in.
Preferably, the insertion loss of the copper clad laminate at 8GHz is 0-0.31 db/in, the insertion loss of the copper clad laminate at 12.89GHz is 0-0.43 db/in, and the insertion loss of the copper clad laminate at 16GHz is 0-0.53 db/in; the peel strength between the micro-rough electrolytic copper foil and the base material is more than 3.5 lb/in.
Preferably, the insertion loss of the copper clad laminate at 12.89GHz is 0-0.42 db/in, the insertion loss of the copper clad laminate at 16GHz is 0-0.52 db/in, the insertion loss of the copper clad laminate at 20GHz is 0-0.63 db/in, and the insertion loss of the copper clad laminate at 30GHz is 0-0.92 db/in; the peel strength between the micro-rough electrolytic copper foil and the base material is more than 3.9 lb/in.
Preferably, the average maximum width of the microcrystallized clusters is less than 5 microns; part of the micro-crystal clusters form a branched structure; each of said microcrystalline clusters having an average height of less than 1 micron; each of said microcrystalline clusters consisting of a plurality of stacks of microcrystals, said microcrystals having an average diameter of less than 0.5 micron; the micro-rough surface of the micro-rough electrolytic copper foil has an Rlr value of less than 1.06.
Preferably, the substrate has a Dk value of less than 3.8 at 1GHz frequency and a Df value of less than 0.002 at 1GHz frequency.
One of the advantages of the present invention is that the micro-rough surface has a good bonding force with the substrate, and insertion loss at high frequency has a good performance, so that loss during signal transmission can be effectively suppressed.
For a better understanding of the features and technical content of the present invention, reference should be made to the following detailed description of the invention and accompanying drawings, which are provided for purposes of illustration and description only and are not intended to limit the invention.
Drawings
FIG. 1 is a schematic side view illustrating one embodiment of the copper foil substrate of the present invention.
Fig. 2 is an enlarged schematic view of section II of fig. 1.
FIG. 3 is a schematic view illustrating a production apparatus of a micro-rough electrolytic copper foil.
FIG. 4 is a scanning electron microscope photograph illustrating the surface morphology of the micro-roughened electrolytic copper foil of example 1.
FIG. 5 is a scanning electron microscope photograph showing the cross-sectional shape of the micro-roughened electrolytic copper foil of example 1.
FIG. 6 is a scanning electron microscope photograph illustrating the surface morphology of the copper foil of comparative example 3.
FIG. 7 is a scanning electron microscope photograph illustrating the cross-sectional form of the copper foil of comparative example 3.
FIG. 8 is a scanning electron microscope photograph illustrating the surface morphology of the copper foil of comparative example 4.
FIG. 9 is a scanning electron microscope photograph illustrating the cross-sectional form of the copper foil of comparative example 4.
Detailed Description
The following description will be made of embodiments of the present invention relating to "micro-rough electrolytic copper foil and copper foil substrate" by specific examples, and those skilled in the art will understand the advantages and effects of the present invention from the disclosure of the present specification. The invention is capable of other and different embodiments and its several details are capable of modification and various other changes, which can be made in various details within the specification and without departing from the spirit and scope of the invention. The drawings of the present invention are for illustrative purposes only and are not intended to be drawn to scale. The following embodiments will further explain the related art of the present invention in detail, but the disclosure is not intended to limit the scope of the present invention.
Referring to fig. 1, the copper foil substrate 1 of the present invention includes a substrate 11 and two micro-rough electrolytic copper foils 12. The micro-rough electrolytic copper foil 12 is bonded to each of the opposite sides of the base material 11. It is to be noted that the copper foil substrate 1 may include only one micro-roughened electrolytic copper foil 12.
The substrate 11 preferably has a low Dk value and a low Df value to suppress insertion loss (insertion loss). Preferably, the Dk value of the substrate 11 at 1GHz frequency is less than 4 and Df value at 1GHz frequency is less than 0.003, and more preferably, the Dk value of the substrate 11 at 1GHz frequency is less than 3.8 and the Df value at 1GHz frequency is less than 0.002.
The base material 11 may be a composite material in which a prepreg sheet is impregnated with a synthetic resin and then cured. Examples of the prepreg sheet include: phenolic cotton paper, resin fiber cloth, resin fiber nonwoven fabric, glass plate, glass woven fabric, or glass nonwoven fabric. Examples of the synthetic resin include: epoxy resin, polyester resin, polyimide resin, cyanate ester resin, bismaleimide triazine resin, polyphenylene ether resin, or phenol resin. The synthetic resin layer may be a single layer or a plurality of layers, and is not limited. Substrate 11 may be selected from, but is not limited to, EM891, IT958G, IT150DA, S7439G, MEGTRON 4, MEGTRON 6, or MEGTRON 7.
Referring to fig. 1 and 2, a micro-roughened electrolytic copper foil 12 is obtained by electrolytically roughening the surface of a copper foil. The electrolytic roughening treatment can treat either surface of the copper foil, and thus, the micro-roughened electrolytic copper foil 12 has a micro-roughened surface 121 on at least one side. In one embodiment of the present invention, a Very Low roughness copper foil (Very Low Profile, VLP) is used as a green foil, and then the rough surface is subjected to roughening treatment.
The micro-rough surface 121 is for adhering to the substrate 11 and includes a plurality of peaks 122, a plurality of V-grooves 123, and a plurality of micro-crystal clusters 124. Two adjacent peaks 122 define a V-shaped groove 123. The average depth of the V-shaped grooves 123 is less than 1.5 microns, preferably less than 1.3 microns, and more preferably less than 1 micron. The average width of the V-shaped grooves 123 is less than 1.5 microns, preferably less than 1.3 microns, and more preferably less than 1 micron.
The average height of the microcrystalline clusters 124 is less than 1.5 microns, preferably less than 1.3 microns, and more preferably less than 1 micron. The average height is the distance from the top of the microcrystalline cluster 124 to the top of the peak 122. The average maximum width of the microcrystalline clusters 124 is less than 5 microns, preferably less than 3 microns. Each microcrystalline cluster 124 is formed by stacking a plurality of microcrystals 125, and the average diameter of the microcrystals 125 is less than 0.5 micron, preferably between 0.05 and 0.5 micron, and more preferably between 0.1 and 0.4 micron. The average number of stacked microcrystals 125 of each microcrystals cluster 124 in its own height direction is 15 or less, preferably 13 or less, more preferably 10 or less, and still more preferably 8 or less. The microcrystals 125, when stacked into microcrystallite clusters 124, may be stacked into a tower-like structure or may extend outward to present a branched structure.
The arrangement of the micro-crystalline clusters 124 is not necessarily limited, and may be a disordered arrangement, or may be an arrangement substantially along the same direction, or may be a plurality of micro-crystalline clusters 124 arranged in a row with the extending direction of each row being partially the same.
The average roughness Rz of the micro-rough surface 121 of the micro-rough electrolytic copper foil 12 is preferably more than 0.5 μm, more preferably more than 1.0. mu.m, still more preferably more than 1.2. mu.m. When the average roughness Rz of the microrough surface 121 is within the above range, a good bonding force with the base material 11 can be obtained, that is, when the average roughness Rz is increased, the bonding force with the base material 11 can be effectively increased, so that the Peel strength (Peel strength) can be effectively increased. Preferably, the peel strength between the micro-rough electrolytic copper foil 12 and the base material 11 is greater than 3lb/in, preferably greater than 3.2lb/in, more preferably greater than 3.5lb/in, and still more preferably greater than 3.7 lb/in. Since the adhesive coated on the micro-rough surface penetrates into the V-shaped groove 123 and the bottom of the micro crystal cluster 124 when the substrate 11 is bonded, the peel strength can be effectively improved after the substrate 11 is bonded.
The form of the micro-rough surface 121 allows sufficient peel strength between the micro-rough electrolytic copper foil 12 and the substrate 11, and effectively suppresses loss during signal transmission. The micro-rough surface 121 has an Rlr value of less than 1.06, preferably less than 1.055, and more preferably less than 1.05. The Rlr value refers to the ratio of the developed length, that is, the ratio of the surface profile length of the object to be measured in a unit length. Higher values indicate a more rugged surface, and when the value is equal to 1, it indicates a completely flat surface. Rlr satisfies the relation of Rlo/L. Where Rlo refers to the measured profile length and L refers to the measured distance.
When the micro-rough electrolytic copper foil 12 has the above-mentioned Rlr value, the copper clad laminate 1 has a better insertion loss performance. The insertion loss of the copper foil substrate 1 at 8GHz is 0 to-0.31 db/in, preferably 0 to-0.305 db/in. The insertion loss of the copper foil substrate 1 at 12.89GHz is 0 to-0.43 db/in, more preferably 0 to-0.42 db/in, still more preferably 0 to-0.41 db/in. The insertion loss of the copper foil substrate 1 at 16GHz is 0 to-0.53 db/in, more preferably 0 to-0.52 db/in, still more preferably 0 to-0.51 db/in. The insertion loss of the copper foil substrate 1 at 20GHz is 0 to-0.635 db/in, preferably 0 to-0.63 db/in, more preferably 0 to-0.62 db/in, still more preferably 0 to-0.61 db/in, still more preferably 0 to-0.6 db/in. The insertion loss of the copper foil substrate 1 at 25GHz is 0 to-0.78 db/in, more preferably 0 to-0.77 db/in, still more preferably 0 to-0.76 db/in, still more preferably 0 to-0.74 db/in. The insertion loss of the copper foil substrate 1 at 30GHz is 0 to-0.935 db/in, more preferably 0 to-0.92 db/in, still more preferably 0 to-0.90 db/in, still more preferably 0 to-0.88 db/in. The micro-rough electrolytic copper foil 12 of the present invention can effectively suppress loss during signal transmission at high frequencies, particularly in the range of 16GHz or higher.
[ method for producing micro-rough electrolytic copper foil ]
The micro-rough electrolytic copper foil 12 is obtained by immersing a green foil in a copper-containing plating solution and then performing electrolytic roughening treatment for a predetermined period of time. In an embodiment of the present invention, a very low roughness copper foil (VLP) is used as a green foil, and the rough surface is subjected to electrolytic roughening treatment. The electrolytic roughening treatment can be carried out by any known apparatus, for example: a continuous electrolysis apparatus, or a batch electrolysis apparatus.
The copper-containing plating solution contains copper ions, acid and metal additives. The copper ion source may be, for example, copper sulfate, copper nitrate, or a combination thereof. The acid may, for example, be sulfuric acid, nitric acid, or a combination thereof. The metal additive may be, for example, cobalt, iron, zinc, or a combination thereof. In addition, the copper-containing plating solution may further contain well-known additives, such as: gelatin, organonitrogen compounds, hydroxyethyl cellulose (HEC), polyethylene glycol (polyethylene glycol), PEG, Sodium 3-Mercaptopropionate (MPS), Sodium polydithiodipropionate (Bis- (Sodium sulfopropyl) -disulphide, SPS), or thiourea-based compounds, but not limited thereto.
The number of roughening treatments is at least two, and the composition of the copper-containing plating solution in each roughening treatment may be the same or different. In one embodiment of the present invention, two copper-containing plating solutions are used for roughening treatment alternately, and the copper ion concentration of the first copper-containing plating solution is preferably between 10 and 30g/l, the acid concentration is preferably between 70 and 100g/l, and the addition amount of the metal additive is preferably between 150 and 300 mg/l. The copper ion concentration of the second group of copper-containing plating solution is preferably between 70 and 100g/l, the acid concentration is preferably between 30 and 60g/l, and the addition amount of the metal additive is preferably between 15 and 100 mg/l.
The power supply method for electrolysis may employ a constant voltage, a constant current, a pulse type waveform, or a saw type waveform, but is not limited thereto. In one embodiment of the invention, the roughening is performed by first applying a first copper-containing bath at a constant current of 18 to 40A/m2Treating the copper-containing plating solution with a second copper-containing plating solution at a constant current of 2.2-5A/m2And (6) processing. Preferably, the first copper-containing plating solution is applied at a constant current of 20 to 33A/m2The treatment is carried out while the second group of copper-containing plating solution is treated with a constant current of 2.27 to 3A/m2And (6) processing. It should be noted that the constant current may be supplied in a pulse-type waveform or a saw-type waveform. In addition, if the power is supplied at a constant voltage, the voltage value applied at each stage of the roughening treatment is ensured so that the current value falls within the above range.
When the number of times of the roughening treatment is three or more, the roughening treatment can be performed by alternately using the first and second copper-containing plating solutions. The current value is controlled between 10 and 16A/m2. In one embodiment of the present invention, the third and fourth roughening treatments are performed by using a first and a second copper-containing plating solutions, respectively, and the current value is controlled to be between 13 and 15A/m2. The current value of the roughening treatment after the fifth roughening treatment is controlled to be less than 5A/m2Preferably progressively decreasing. It should be noted that the constant current may be supplied in a pulse-type waveform or a saw-type waveform. Further, if the power is supplied at a constant voltage, the voltage value applied at each stage of the roughening treatment is ensured so that the current value falls within the above range.
It is worth mentioning that the arrangement of the micro crystal clusters 124 on the micro-rough surface 121 and the extending direction of the V-shaped groove 123 can be controlled by the flow field of the copper-containing plating solution. When no flow field is applied or turbulent flow is formed, the micro crystal clusters 124 can be arranged in disorder; when the flow field is controlled to flow along a specific direction on the surface of the copper foil, a structure which is approximately arranged along the same direction is formed. However, the method of controlling the alignment of the micro crystal clusters 124 and the extending direction of the V-grooves 123 is not limited thereto, and the non-directional V-grooves 123 may be formed by scratching with a steel brush in advance, and may be adjusted by a manufacturer in any known manner.
In one preferred embodiment of the present invention, the roughening treatment is carried out by a continuous electrolytic apparatus having a plurality of cells and a plurality of electrolytic rolls. Wherein, the first group of copper-containing plating solution and the second group of copper-containing plating solution are alternately contained in each groove. The power supply method adopts constant current. The production speed is controlled to be 5 to 20 m/min. The production temperature is controlled at 20 to 60 ℃.
It should be noted that the method for manufacturing the micro-rough electrolytic Copper foil can also be used for processing High Temperature expanded Copper (HTE) and Reverse Treated Copper (RTF) foil. The copper foil can be obtained by performing electrolytic roughening treatment on the glossy surface of the high-temperature expanded copper foil.
The structure of each layer of the copper foil substrate 1 and the manufacturing method have been explained above, and the advantages of the present invention will be explained below by exemplifying embodiments 1 to 3 and comparing with comparative examples 1 to 4.
[ example 1]
Referring to FIG. 3, the micro-rough electrolytic copper foil is subjected to a roughening treatment by using a continuous electrolytic apparatus 2. The continuous electrolytic apparatus 2 comprises a feed roll 21, a collecting roll 22, six troughs 23 between the feed roll 21 and the collecting roll 22, six electrolytic roll groups 24 respectively placed above the troughs 23, and six auxiliary roll groups 25 respectively placed in the troughs 23. A set of platinum electrodes 231 is provided in each groove 23. Each of the electrolytic roll sets 24 includes two electrolytic rolls 241. Each set of auxiliary rollers 25 comprises two auxiliary rollers 251. The platinum electrode 231 in each cell 23 and the corresponding electrolytic roll set 24 are electrically connected to the anode and cathode of an external power supply, respectively.
In this example 1, a very low roughness copper foil (VLP) was used as a raw foil, which was purchased from jinju development ltd (model VL 410). The raw foil is wound on the delivery roll 21, then sequentially wound on the electrolytic roll group 24 and the auxiliary roll group 25, and then wound on the collecting roll 22. The copper-containing bath composition and plating conditions in each tank 23 are shown in table 1, in which the source of copper ions is copper sulfate. The rough surface of the green foil is roughened sequentially from the first groove to the sixth groove at a production speed of 10m/min to obtain a micro-rough electrolytic copper foil with a roughness Rz of 1.29 μm. And then, two pieces of micro-rough electrolytic copper foil are taken to be attached to one piece of base material MEGTRON 7, and the manufacturing is finished.
In this embodiment 1, the surface and cross-sectional structures of the film are observed by a scanning electron microscope and are shown in fig. 4 and 5, respectively.
In this example 1, the peel strength of the micro-rough electrolytic copper foil was determined by coating the micro-rough surface with a silane coupling agent and adhering the coated micro-rough surface to the substrate MEGTRON 7. After curing, measurements were made according to IPC-TM-6504.6.8 test method. The test results are shown in Table 2.
The Rlr values of the electrodeposited copper foil with micro-roughness of example 1 were measured by a shape measuring laser microscope (manufacturer: Keyence, model: VK-X100). The test results are shown in Table 2.
In this example 1, the insertion loss of the Micro-roughened electrolytic copper foil was measured by a Micro-strip line (characteristic impedance 50 Ω) method and detected at frequencies of 4GHz, 8GHz, 12.89GHz, 16GHz, 20GHz, 25GHz and 30GHz, respectively. The test results are shown in Table 2.
[ examples 2 and 3]
The raw foil, the electrolytic apparatus and the copper-containing bath were the same as in example 1, the plating conditions were as shown in Table 1, and the production rate was 10 m/min. And then, two pieces of micro-rough electrolytic copper foil are taken to be attached to one piece of base material MEGTRON 7, and the manufacturing is finished. The measurement was conducted in the same manner as in example 1, and the test results are shown in Table 2.
Comparative examples 1 and 2
The raw foil, the electrolytic apparatus and the copper-containing bath were the same as in example 1, the plating conditions were as shown in Table 1, and the production rate was 10 m/min. And then, two pieces of micro-rough electrolytic copper foil are taken to be attached to one piece of base material MEGTRON 7, and the manufacturing is finished. The measurement was conducted in the same manner as in example 1, and the test results are shown in Table 3.
Comparative example 3
The surface and cross-sectional structures of the copper foil (model: CF-T4X-SV, hereinafter referred to as CF-T4X-SV copper foil) having an extremely low roughness manufactured by Futian Metal foil powder industries, Ltd. were observed by scanning electron microscopy, and are shown in FIG. 6 and FIG. 7, respectively. Two CF-T4X-SV copper foils were attached to a substrate MEGTRON 7, and the peel strength, Rlr, and insertion loss were measured, and the test results are shown in Table 3.
Comparative example 4
The surface and cross-sectional structures of the extremely low roughness copper foil (model: HS1-M2-VSP, hereinafter referred to as HS1-M2-VSP copper foil) produced by Taiwan copper foil Co., Ltd. were observed by a scanning electron microscope and shown in FIG. 8 and FIG. 9, respectively. Two sheets of HS1-M2-VSP copper foil were laminated to one substrate MEGTRON 7, and their peel strength, Rlr, and insertion loss were measured, and the test results are shown in Table 3.
TABLE 1
Referring to fig. 4 and 5, the micro-rough surface of example 1 is formed by stacking a plurality of particles having a particle size of less than 0.5 μm to form micro-crystal clusters, and the micro-crystal clusters are spaced apart from each other significantly. As can be seen from the cross-sectional view, the micro-rough surface includes a plurality of spaced V-shaped grooves with a depth of less than 0.6 μm. The micro-crystal clusters are distributed non-uniformly and are mostly concentrated on the tops of the peaks, namely concentrated between the V-shaped grooves.
Referring to fig. 6 and 7, the surface of the CF-T4X-SV copper foil is uniformly coated with a plurality of micro-crystals having a particle size of more than 1 μm, and the micro-crystals are not aggregated to form clusters. It is known from the sectional view that the microcrystals are uniformly distributed on the surface and are not concentrated at specific positions. Furthermore, the average height of the microcrystals is greater than 1.5 microns.
Referring to fig. 8 and 9, the HS1-M2-VSP copper foil surface was uniformly coated with a majority of crystals having a particle size of greater than 0.5 μ M, and most of the crystals were dispersed with each other and a minority of the crystals were clustered. It is known from the cross-sectional views that the crystals are clearly spaced apart from each other and are also uniformly distributed over the surface and not concentrated at specific locations. In addition, the height of the microcrystals is between 1 and 2 microns.
TABLE 2
TABLE 3
Referring to tables 2 and 3, examples 1 to 3 exhibited peel strengths of at least 3.96lb/in, between commercially available copper foils (comparative examples 3, 4), and at least 32% greater than the industry standard 3 lb/in. Therefore, the micro-rough electrolytic copper foil has good bonding force with the substrate, is beneficial to the subsequent processing and maintains the product yield.
Regarding the behavior of insertion loss, the insertion loss between the frequencies 8GHz and 30GHz in examples 1 to 3 is substantially better than that in comparative examples 1 to 4. It is worth mentioning that the present invention has better insertion loss performance than the commercial products (comparative examples 3 and 4) in the high frequency range of 12.89GHz or more. It is worth mentioning that the signal loss of the copper foil substrate at high frequency can be obviously inhibited by controlling the surface morphology of the micro-rough surface and adjusting the Rlr value to be less than 1.059. In addition, the lower the value of Rlr, the more the effect of reducing signal loss can be found.
As can be seen from the above, the micro-rough electrolytic copper foil of the present invention further optimizes the insertion loss performance while maintaining good peel strength, and can effectively suppress signal loss.
The disclosure is only a preferred embodiment of the invention, and is not intended to limit the scope of the claims, so that all technical equivalents and modifications using the contents of the specification and drawings are included in the scope of the claims.

Claims (10)

1. A micro-rough electrodeposited copper foil comprising a micro-rough surface having a plurality of peaks, a plurality of V-grooves, and a plurality of micro-crystalline clusters, two adjacent peaks defining a V-groove, said V-grooves having an average depth of less than 1 micron, said micro-crystalline clusters being located at the tops of said peaks, wherein each of said micro-crystalline clusters is formed by a plurality of micro-crystalline stacks, said micro-crystals having an average diameter of less than 0.5 micron, said micro-crystalline clusters having an average height of less than 1.5 microns;
wherein the micro-rough surface of the micro-rough electrolytic copper foil has an Rlr value of less than 1.06.
2. The micro-rough electrolytic copper foil according to claim 1, wherein each of the micro-crystalline clusters has an average height of less than 1.3 μm.
3. The micro-rough electrolytic copper foil according to claim 2, wherein the average stacking number of the microcrystals in the height direction thereof per one of the microcrystal clusters is 15 or less; the average maximum width of the microcrystallized clusters is less than 5 microns; part of the microcrystalline clusters form a branched structure.
4. The micro-rough electrolytic copper foil according to any one of claims 1 to 3, wherein the micro-rough surface of the micro-rough electrolytic copper foil has an Rlr value of less than 1.055.
5. A copper foil substrate, comprising:
a substrate; and
a micro-rough electrolytic copper foil, which comprises a micro-rough surface attached to the substrate, wherein a plurality of convex peaks, a plurality of V-shaped grooves and a plurality of micro-crystal clusters are formed on the micro-rough surface, two adjacent convex peaks define a V-shaped groove, the average depth of the V-shaped groove is less than 1 micron, the micro-crystal clusters are positioned at the tops of the convex peaks, each micro-crystal cluster is formed by stacking a plurality of micro-crystals, the average diameter of the micro-crystals is less than 0.5 micron, and the average height of the micro-crystal clusters is less than 1.5 microns;
wherein the insertion loss of the copper foil substrate at 20GHz is between 0 and-0.635 db/in;
wherein the peel strength between the micro-rough electrolytic copper foil and the base material is more than 3 lb/in.
6. The copper foil substrate according to claim 5, wherein the copper foil substrate has an insertion loss at 30GHz of 0 to-0.935 db/in.
7. The copper foil substrate of claim 6, wherein the copper foil substrate has an insertion loss at 8GHz of 0 to-0.31 db/in, an insertion loss at 12.89GHz of 0 to-0.43 db/in, an insertion loss at 16GHz of 0 to-0.53 db/in; the peel strength between the micro-rough electrolytic copper foil and the base material is more than 3.5 lb/in.
8. The copper foil substrate of claim 7, wherein the copper foil substrate has an insertion loss at 12.89GHz of 0 to-0.42 db/in, an insertion loss at 16GHz of 0 to-0.52 db/in, an insertion loss at 20GHz of 0 to-0.63 db/in, an insertion loss at 30GHz of 0 to-0.92 db/in; the peel strength between the micro-rough electrolytic copper foil and the base material is more than 3.9 lb/in.
9. The copper foil substrate according to claim 5, wherein the average maximum width of the micro-crystalline clusters is less than 5 microns; part of the micro-crystal clusters form a branched structure; each of said microcrystalline clusters having an average height of less than 1 micron; the micro-rough surface of the micro-rough electrolytic copper foil has an Rlr value of less than 1.06.
10. The copper foil substrate according to claim 5, wherein the base material has a Dk value of less than 3.8 at a frequency of 1GHz and a Df value of less than 0.002 at a frequency of 1 GHz.
CN201811132277.4A 2018-09-27 2018-09-27 Micro-rough electrolytic copper foil and copper foil substrate Active CN110952117B (en)

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