HK1047854A - Surface-treated copper foil, method of producing the surface-treated copper foil, and copper-clad laminate employing the surface-treated copper foil - Google Patents
Surface-treated copper foil, method of producing the surface-treated copper foil, and copper-clad laminate employing the surface-treated copper foil Download PDFInfo
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Description
Technical Field
The present invention relates to a surface-treated copper foil subjected to an anti-corrosion treatment, a method for producing the same, and a copper-clad laminate using the surface-treated copper foil.
Background
In general, copper foil is widely used in the electrical industry and the electronic industry as a material for producing printed wiring boards. Electrodeposited copper foils are typically bonded by hot pressing to an insulating polymer substrate such as a glass epoxy substrate, phenolic polymer substrate or polyimide substrate to form a copper-clad laminate, and the laminate thus produced is used to make printed wiring boards.
In particular, a copper foil having formed on the surface thereof a zinc-copper-nickel ternary alloy plating layer as an anti-corrosion layer, which has excellent heat resistance (generally referred to as UL heat resistance) and resistance to chemicals (particularly to hydrochloric acid) in the manufacture of printed wiring boards, has been widely used. Among these characteristics, the hydrochloric acid resistance can be evaluated by the following procedure. In the experiment, a printed wiring board having a copper foil pattern was immersed in a hydrochloric acid solution of a predetermined concentration for a predetermined period of time. The peel strength before and after immersion was measured without measuring the amount of hydrochloric acid solution that penetrated between the copper foil pattern and the circuit board substrate interface. The percent loss of peel strength after immersion to initial peel strength was calculated and used as an indicator of hydrochloric acid resistance.
In general, as the line width of a copper foil pattern of a printed wiring board decreases, a copper foil used for producing the printed wiring board is required to have a greater hydrochloric acid resistance. When the peel strength of the copper foil is greatly reduced with respect to the initial peel strength, the interface between the copper foil pattern and the substrate is easily penetrated by the hydrochloric acid solution and easily corroded. In printed wiring boards made of these copper foils, the copper wiring patterns may be peeled off from the substrate due to the treatment of the copper foils with various acidic solutions during the production of the printed wiring boards.
In recent years, the thickness, weight and size of electronic and electrical equipment have been decreasing, and accordingly, there has been a demand for further decreasing the line width of a copper foil pattern formed on a printed wiring board. Thus, there is a further demand for copper foils used in the manufacture of printed wiring boards to have higher hydrochloric acid resistance.
Some documents, such as japanese patent laid-open publication No. 318997 in 1992 and No. 321458 in 1995, disclose a copper foil having an anti-corrosion layer formed by combining a zinc-copper-nickel ternary alloy plating layer with a chromate layer and having excellent hydrochloric acid resistance. At the time of filing the above patent application, it is common to measure a copper foil pattern sample having a line width of 1mm to test hydrochloric acid resistance. The specification of the above publication discloses that the test is carried out on a copper foil pattern sample obtained from a copper foil measuring a line width of 1 mm. Actually, the present inventors produced a copper foil by the method disclosed in the above publication on the basis of the test, and conducted a test of hydrochloric acid resistance using a copper foil pattern sample having a line width of 1mm obtained from the copper foil. The results are similar to those disclosed in those publications. Some documents, such as the following laid-open patent publications, disclose methods for improving the hydrochloric acid resistance of a copper foil, which comprise treating the surface to be bonded to a substrate with a silane coupling agent.
However, by testing the hydrochloric acid resistance of a copper foil pattern formed of a copper foil prepared for testing according to the method disclosed in the above-mentioned publication of published patent application with a line width of 0.2mm, the present inventors found that the hydrochloric acid resistance of most of the samples was a peel strength loss of 15% or more. With respect to the current test of hydrochloric acid resistance of copper foil, it is agreed that unless a copper pattern sample having a line width of about 0.2mm is used for the test, it is difficult to ensure the quality of the product which has reached the latest tendency to reduce the line width of the copper foil pattern. For example, even when a copper foil pattern made of a copper foil having a line width of 1mm is measured, the hydrochloric acid resistance of the copper foil is about 3% of the loss of peel strength, but when a copper pattern made of the copper foil having a line width of 0.2mm is measured, the same copper foil reaches a loss of peel strength exceeding 10% of the hydrochloric acid resistance. In some cases, the percent peel strength loss reached 20% more. The quality of copper foil producing fine pitch copper foil patterns cannot be tested by conventional test methods including measuring copper foil patterns with a line width of 1 mm.
In the copper-clad laminate, a silane coupling agent is present between an anti-corrosion layer formed on a metallic copper foil and a substrate formed of various organic materials. However, the details of the silane coupling agent, such as the method of using it, have not been sufficiently studied. Several patents have been filed so far in connection with copper foils using silane coupling agents.
For example, japanese patent publications No. 15654 in 1985 and 19994 in 1990 disclose a copper foil on the surface of which a zinc or zinc alloy layer is formed, a chromate layer is formed on the zinc or zinc alloy layer, and a silane coupling agent layer is formed on the chromate layer. As judged from a comprehensive consideration of the above patent publications, these patents focused attention on the drying treatment after the formation of the chromate layer and the silane coupling agent treatment after the drying. However, the present inventors have found that it is difficult to obtain a copper foil of desired properties unless a particular factor can be controlled. That is, the copper foil produced by the method described above was large in variation of the properties and quality of the copper foil, particularly the hydrochloric acid resistance and moisture resistance, among lots on the basis of the test.
Japanese patent publication No. 17950 in 1990 discloses that the hydrochloric acid resistance of a copper foil can be increased by treating the copper foil with a silane coupling agent, but there is no specific indication as to how the moisture resistance of the copper foil is. In recent years, corresponding problems have arisen in the field of semiconductor device packaging in forming micro-circuits and multilayer printed wiring boards. Due to the poor moisture resistance of the copper clad laminate used, problems arise such as delamination of the multilayer printed wiring board and deterioration of the pressure cooker performance of the packaged semiconductor device.
As described above, with respect to the formation of a silane coupling agent on an anti-corrosion layer composed of a zinc or zinc alloy layer on a copper foil and a chromate layer formed on the zinc or zinc alloy layer, all inventions do not consider the combination of the silane coupling agent and the anti-corrosion layer, the surface condition and drying condition of the anti-corrosion layer at the time of adsorption of the silane coupling agent, nor exert the maximum effect on the silane coupling agent used.
Drawings
FIGS. 1(a) and 1(b) are each a schematic cross-sectional view of a surface-treated copper foil. Fig. 2 and 3 are general sectional views schematically showing a surface treatment apparatus used for producing a surface-treated copper foil.
Disclosure of Invention
The present inventors have studied to provide a surface-treated copper foil capable of repeatedly obtaining a peel strength loss of 10% or less in hydrochloric acid resistance (which result is obtained by measuring a copper foil pattern made of a copper foil having a line width of 0.2 mm), which is obtained by maximizing the effect of a silane coupling agent applied to a copper foil having a surface coated with an anti-corrosion layer formed of a zinc-copper-nickel ternary alloy. The inventors have also studied to impart excellent moisture resistance to the surface-treated copper foil. In the intensive studies conducted by the inventors, three important factors, namely the condition of the corrosion resistant layer of the copper foil before it is treated with the coupling formulation, were found, which are the most important factors; time of treatment with a silane coupling agent; drying conditions after the coupler treatment. These three factors must be carefully treated in order to maximize the effect of the silane coupling agent used. The present invention has been accomplished on the basis of these findings.
The present invention provides, in claim 1, a surface-treated copper foil for use in the production of a printed wiring board, the surface of the copper foil being subjected to a nodular treatment and an anti-corrosion treatment, wherein the anti-corrosion treatment comprises: forming a zinc-copper-nickel ternary alloy electroplated layer on the surface of the copper foil; forming an electrolytic chromate layer on the zinc-copper-nickel ternary alloy plating layer; forming a silane coupling agent adsorption layer on the electrolytic chromate layer; finally, the copper foil is dried for 2-6 seconds at a temperature of 105-200 ℃.
The invention of claim 2 provides a surface-treated copper foil for use in the production of a printed wiring board, the surface of the copper foil being subjected to a nodular treatment and an anti-corrosion treatment, wherein the nodular treatment comprises: depositing fine copper particles on the surface of the copper foil; carrying out closed electroplating to prevent the shedding of the fine copper particles; further depositing and accumulating fine copper particles; the anti-corrosion treatment comprises the following steps: forming a zinc-copper-nickel ternary alloy electroplated layer on the surface of the copper foil; forming a silane coupling agent adsorption layer on the electrolytic chromate layer; finally, the copper foil is dried for 2-6 seconds at a temperature of 105-200 ℃.
The difference between the copper foils of claims 1 and 2, as shown in fig. 1, is in the form of fine copper particles that produce an anchor effect on the bonding substrate. Specifically, fig. 1(a) is a schematic cross-sectional view of the surface-treated copper foil according to claim 1. As shown in fig. 1(a), under the condition that the burnt deposit is formed, fine copper particles are formed on the surface of the copper foil, and seal plating is performed to prevent the fine copper particles from falling off. During the closed plating, copper is deposited under leveling plating (leveling) conditions. As shown in fig. 1(b), which is a schematic sectional view of the surface-treated copper foil according to claim 2, the copper foil is characterized in that ultrafine copper particles (which may be called whisker plating by those skilled in the art) are deposited on the seal plating layer of the surface-treated copper foil according to claim 1. Very fine copper particles are typically produced by using a copper electroplating bath containing arsenic. The corrosion-resistant layer and the silane coupling agent adsorption layer are not shown in fig. 1(a) and 1 (b).
The surface-treated copper foil as set forth in claim 2, wherein the ultrafine copper particles are formed in one nodular treatment step, and the surface of the copper foil is roughened by the ultrafine copper particles, thereby improving adhesion to an organic substrate. Therefore, the copper foil ensures higher adhesiveness to a substrate than the surface-treated copper foil according to claim 1.
The surface-treated copper foil according to claim 1 is preferably produced by the method according to claim 5 or 6. In claim 5, there is provided a method for producing a surface-treated copper foil for a printed wiring board, which comprises: forming a nodular treated surface on a surface of a copper foil; carrying out corrosion resistance treatment on the copper foil; performing adsorption of a silane coupling agent on the nodular-treated surface; and (5) drying. Wherein the anti-corrosion treatment comprises electroplating zinc-copper-nickel ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; then drying the surface of the copper foil; adsorbing a silane coupling agent; drying the copper foil in a high-temperature atmosphere for 2-6 seconds at a temperature of 105-180 ℃.
In claim 6, there is provided a method for producing a surface-treated copper foil for printed wiring boards, which comprises: forming a nodular treated surface on a surface of a copper foil; carrying out corrosion resistance treatment on the copper foil; performing adsorption of a silane coupling agent on the nodular-treated surface; and (5) drying. Wherein the anti-corrosion treatment comprises electroplating zinc-copper-nickel ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; adsorption of the silane coupling agent is carried out under conditions that do not result in surface drying of the electrolytic chromate treatment; drying the copper foil in high temperature air for 2-6 seconds, wherein the temperature is 110-200 ℃.
The method for producing a surface-treated copper foil according to claims 5 and 6 is different in that the timing of carrying out the adsorption of the alkane coupling agent is selected either to carry out the adsorption treatment after completion of the drying of the electrolytically chromated surface of the copper foil or to carry out the adsorption treatment without waiting for the drying of the electrolytically chromated surface. The differences between the two will be described below in connection with experimental data. In fact, the surface-treated copper foil obtained by the latter method, i.e., the surface-treated copper foil obtained by performing the adsorption treatment without waiting for the electrolytic chromate treatment to dry the surface, has a good quality of resistance to hydrochloric acid.
The surface-treated copper foil according to claim 2 is preferably produced by the method according to claim 7 or 8. The method for producing a surface-treated copper foil set forth in claim 7, which comprises: forming a nodular treated surface on a copper foil; carrying out corrosion resistance treatment on the copper foil; performing adsorption of a silane coupling agent on the nodular-treated surface; and (5) drying. Wherein the nodular treatment comprises depositing fine copper particles on the surface of the copper foil; sealing electroplating is carried out to prevent the shedding of the fine copper particles; then depositing extremely fine copper particles. The anti-corrosion treatment comprises electroplating zinc-copper-nickel ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; drying the surface of the copper foil; adsorbing a silane coupling agent; drying the copper foil in high temperature air for 2-6 seconds, wherein the temperature is 105-180 ℃.
Claim 8 proposes a method for producing a surface-treated copper foil, which comprises: forming a nodular treated surface on a copper foil; carrying out corrosion resistance treatment on the copper foil; performing adsorption of a silane coupling agent on the nodular-treated surface; and (5) drying. Wherein the nodularization treatment comprises the steps of depositing fine copper particles on the surface of the copper foil, and carrying out closed electroplating to prevent the fine copper particles from falling off; further precipitating the active fine copper particles. The anti-corrosion treatment comprises electroplating zinc-copper-nickel ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; adsorption of the silane coupling agent is carried out without waiting for the surface drying of electrolytic chromate treatment; drying the copper foil in high temperature air for 2-6 seconds, wherein the temperature is 110-200 ℃.
The methods for producing surface-treated copper foils according to claims 7 and 8 are different in that the timing of performing adsorption of the silane coupling agent, that is, the adsorption treatment is performed after completion of drying of the electrolytically chromate-treated surface of the copper foil or the adsorption treatment is performed without waiting for drying of the electrolytically chromate-treated surface, similarly to the differences of claims 5 and 6. The differences between the two will be described below in connection with experimental data. However, claims 5 and 6 differ from claims 7 and 8 in that their respective nodularization treatment steps differ. Specifically, in claims 5 and 6, the nodular treatment comprises depositing fine copper particles on the surface of the copper foil, and then performing seal plating to prevent the fine copper particles from falling off. However, in claims 7 and 8, the nodularization treatment includes re-depositing the fine copper particles after completion of the blocking plating. The differences between them will be described below in connection with experimental data. In fact, the surface-treated copper foil obtained by the latter method, i.e., "surface-treated copper foil obtained by adsorption treatment without waiting for the electrolytic chromate treatment to dry the surface", has a good quality of resistance to hydrochloric acid.
The surface-treated copper foil of the present invention, i.e., the production method of the surface-treated copper foil, will be described below with reference to claims 5 to 8. Unless otherwise stated, the conditions for each production step are fixed. The production steps of the surface treated copper foil are as follows: adding an electrolyte containing a copper component between the drum cathode and the lead anode to perform electrolysis, the lead anode and the cathode face each other to surround the drum cathode; rolling out the produced thin copper foil from the rotating cathode to obtain a copper layer (foil); the obtained copper foil is subjected to surface treatment including nodularization treatment, corrosion resistance treatment and silane coupling agent treatment. The copper layer may be formed from a copper ingot by rolling, i.e., may be a rolled copper foil. Throughout the specification, "copper layer (copper foil)" may be simply referred to as "copper foil" or, in some cases, used for clarity.
Next, the surface treatment steps will be described in order. The surface-treated copper foil of the present invention is obtained by subjecting a copper foil to surface treatment using an apparatus generally called a surface treatment apparatus. In practice, the copper foil is unwound from a roll in one direction and conveyed to a surface treatment apparatus in a suitably arranged rinsing bath. In this apparatus, a copper foil is passed through an acid pickling tank, a nodular treatment tank in which fine copper particles are formed on the surface of the copper foil, a ternary alloy corrosion-resistant tank, an electrolytic chromate treatment-corrosion-resistant tank, and a drying section, which are arranged in series, to obtain a surface-treated copper foil product.
As shown in fig. 2 (a schematic cross-sectional view of a surface treatment apparatus), the unwound copper foil is passed through an apparatus production line (respective grooves and steps) in a wound manner. The surface treatment can also be carried out in a gap-wise manner, i.e. the production line can be divided into several sections.
In the pickling tank, pickling is performed to completely remove the oily substance and the surface oxide film on the surface of the copper foil. The copper foil is cleaned on the surface by an acid washing tank to ensure uniform electrodeposition in the next step. The acid washing solution is not particularly limited, and various solutions can be used, such as a hydrochloric acid solution, a sulfuric acid solution, and a sulfuric acid-hydrogen peroxide solution. The concentration and temperature of the pickling solution can be determined according to the characteristics of the production line.
After completion of the acid washing of the copper foil, the copper foil is transferred to a clean water tank. Subsequently, the water-washed copper foil is transferred to a bath in which fine copper particles are formed on the surface thereof. There is no particular limitation on the electrolytic solution containing the copper component used in the above-mentioned tank. However, electrolysis is carried out under conditions that form a burnt deposit, which deposits fine copper particles. Therefore, in the above-mentioned used tank, the concentration of the electrolytic solution for depositing fine copper particles is adjusted to be lower than that of the solution for producing the copper foil, so as to achieve the condition of burning-out deposition. The conditions for forming the burn-out deposit are not particularly limited, depending on the characteristics of the production line. For example, when a copper sulfate solution is used, the conditions are as follows:the copper concentration is 5-20g/l, the free sulfuric acid concentration is 50-200g/l, or additives (alpha-naphthalene quinoline, dextrin, glue, thiourea, etc.) can be added, the solution temperature is 15-40 deg.C, and the current density is 10-50A/dm2。
The seal plating is performed to prevent separation of the deposited fine copper particles. The closed electroplating step is to perform uniform copper deposition, i.e. to prevent the separation of the deposited fine copper particles and to cover the fine copper particles with copper under the condition of leveling electroplating. Therefore, the copper electrolyte used for the close plating should have a higher concentration than the copper electrolyte used for the deposition of fine copper particles. The conditions for the closed plating are not particularly limited, depending on the characteristics of the production line. For example, when a copper sulfate solution is used, the conditions are as follows: the copper concentration is 50-80g/l, the free sulfuric acid concentration is 50-150g/l, the solution temperature is 40-50 ℃, and the current density is 10-50A/dm2。
In the method for producing the surface-treated copper foil according to claim 2 according to claim 7 or 8, the extremely fine copper particles are generally formed using an electrolytic solution containing a copper component and arsenic. For example, when a copper sulfate solution is used, the conditions are as follows: the copper concentration is 10g/l, the free sulfuric acid concentration is 1.5g/l, the solution temperature is 38 ℃, and the current density is 30A/dm2。
However, in recent years, since environmental problems have become a concern, the use of components harmful to the human body is avoided as much as possible. In the present invention, the above-mentioned arsenic is used for the formation of ultrafine copper particles. However, as described in claim 9, the copper-containing electrolyte solution in which 9-phenylacridine is added instead of arsenic is most preferable in the present invention. The 9-phenylacridine functions similarly to arsenic during electrolysis to deposit copper. In short, 9-phenylacridine enables adjustment of the size of the deposited fine copper particles and uniform deposition. In order to form ultrafine copper particles, the electrolyte contains 5-10g/l of copper, 100-120g/l of free sulfuric acid and 50-300mg/l of 9-phenylacridine. The electrolyte is at 30-40 deg.C and current density of 20-40A/dm2When electrolysis is performed under the conditions, electrolysis can be stably performed.
In the following corrosion-resistant bath, treatment for preventing oxidation-induced corrosion is performed on the surface thereof depending on the purpose of use of the copper foil, so that the copper foil is not affected, for example, as in the production of copper-clad laminates and printed wiring boards. In the present invention, the anti-corrosion treatment is performed by a combination of zinc-copper-nickel ternary alloy plating and chromate plating.
When zinc-copper-nickel ternary alloy plating is performed, a plating bath such as a pyrophosphate plating bath is used because the solution of the bath is chemically stable in long-term storage and has excellent stability to electric current. For example, when a pyrophosphate plating bath is used, the plating conditions are: zinc concentration of 2-20g/l, copper concentration of 1-15g/l, nickel concentration of 0.5-5g/l, potassium pyrophosphate concentration of 70-350g/l, solution temperature of 30-60 deg.C, pH of 9-10, and current density of 3-8A/dm2The electrolysis time is 5-15 seconds.
As set forth in claim 3, the composition of the ternary zinc-copper-nickel alloy plating layer is preferably 66.9 to 20% by weight of zinc, 30 to 70% by weight of copper and 0.1 to 10% by weight of nickel. The hydrochloric acid resistance can be most effective when the silane coupling agent is adsorbed onto a zinc-copper-nickel ternary alloy plating layer containing such a composition and dried in the manner mentioned below. This is why this combination is the best. In addition, the zinc-copper-nickel ternary alloy plating in this composition range can be performed on the surface of the copper foil very reliably. Thus, this composition range is also suitable from the viewpoint of yield.
And after the zinc-copper-nickel ternary alloy electroplating is finished, cleaning the electroplated copper foil. Subsequently, a chromate layer is formed on the surface of the cleaned copper foil by electrolysis. Although there is no particular limitation on the conditions of electrolysis, the optimum conditions are as follows: chromic acid concentration of 3-7g/l, solution temperature of 30-40 deg.C, pH of 10-12, and current density of 5-8A/dm2The electrolysis time is 5-15 seconds. After chromate treatment under the above conditions, a uniform coating layer was formed on the surface of the plated copper foil.
In the method for producing the surface-treated copper foil claimed in claim 5, after completion of drying of the electrolytically chromate-treated surface of the copper foil, adsorption treatment of a silane coupling agent is performed. In this case, a drying step is added after the rinsing step after completion of the electrolytic chromate treatment performed in the surface treatment apparatus. In contrast, in the method for producing the surface-treated copper foil according to claim 6, the adsorption treatment is carried out immediately after the formation of the electrolytic chromate layer without waiting for the surface drying of the electrolytic chromate treatment and cleaning.
In this case, the method for forming the silane coupling agent layer is not particularly limited, and methods such as immersion, shower, and spray may be employed. Any method can be used depending on the production steps as long as it can contact the copper foil and the solution containing the silane coupling agent in the most uniform form.
As described in claim 4, any of the silane coupling agents of the group consisting of an alkenyl functional silane, an epoxy group-introduced silane, an acryl functional silane, an amino group-introduced silane and a mercapto functional silane can be used. When these silane coupling agents are used on the surface of a copper foil to be bonded to a substrate, it is important that the coupling agents do not affect the subsequent etching step and also do not affect the properties of the resulting printed wiring board.
More specifically, a silane coupling agent containing glass cloth in a prepreg for producing a printed wiring board may also be used. Examples of such coupling agents include vinyltrimethoxysilane, vinylphenyltrimethoxysilane, gamma-isobutenyloxypropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, 4-glycidylbutyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N-beta- (diaminoethyl) -gamma-aminopropyltrimethoxysilane, N-3- (4- (3-aminopropylpropoxy) butoxy) propyl-3-aminopropyltrimethoxysilane, imidazolylsilanes, triazinylsilanes and gamma-mercaptopropyltrimethoxysilane.
These silane coupling agents are dissolved in water as a solvent at a concentration of 0.3 to 15 g/l. The prepared solution was used at room temperature. The silane coupling agent is coupled with OH groups of the anti-corrosion layer of the copper foil through condensation to form a coating layer. Thus, a coupling effect commensurate with an increase in concentration cannot be obtained with an excessively high concentration of the coupling agent solution, which is determined depending on the conditions of the treatment such as the treatment rate. However, when the concentration is less than 0.3g/l, the adsorption of the silane coupling agent is too slow to achieve a result satisfying economic efficiency, and the adsorption is also not uniform. When the concentration exceeds 15g/l, the adsorption rate is not increased so much, and the hydrochloric acid resistance is not increased so much. Such an adsorption rate is economically disadvantageous.
And finally, carrying out a drying step. This step not only removes the water but also accelerates the condensation reaction of the adsorbed coupling agent with the OH groups on the surface of the corrosion resistant layer, thereby completely evaporating the water produced by the condensation reaction. The drying step should not be carried out at a temperature at which the functional group of the silane coupling agent, which undergoes a chain bond with the substrate resin during the bonding of the silane coupling agent layer to the substrate, is destroyed or decomposed, because if the functional group of the silane coupling agent, which forms a chain bond with the substrate resin, is destroyed or decomposed, the adhesion between the copper foil and the substrate is deteriorated, so that the adsorbed silane coupling agent cannot exert the maximum effect.
In particular, copper foil (i.e., a metal material) has a fast thermal conductivity compared to a glassy material or an organic material (e.g., plastic) to which a silane coupling agent is commonly applied. Thus, the silane coupling agent adsorbed on the copper foil is very sensitive to heat, i.e., high temperature during drying and radiant heat from a heat source. When the drying is performed by using hot air, the temperature of the copper foil is very rapidly increased by the hot air blown from the blower at this time, and the drying condition must be carefully determined. Generally, when drying is performed, only the temperature of the atmosphere, i.e., blast air, in the drying furnace is measured. However, in the present invention, since it is critical to control the temperature of the copper foil itself, the drying can be well performed by passing the copper foil through the heating furnace for 2 to 6 seconds. The drying method is not particularly limited, and drying may be performed by using an electric heater or hot air blowing. The key is that the temperature of the copper foil itself must be controlled within a predetermined range. In the present invention, the drying time and the drying temperature are set within a certain range. This is because the rate of temperature rise of the copper foil is different when the production rate of the surface-treated copper foil is slightly different or when the thickness of the copper foil is not uniform. Therefore, the actual operating conditions should be set within the above range according to the type of product to be manufactured.
In the drying conditions, the drying temperature used after completion of the electrolytic chromate treatment, that is, the silane coupling agent treatment performed after the copper foil has been dried and the silane coupling agent treatment performed without waiting for the drying of the copper foil, is selected to suit the particular silane coupling agent treatment. The reason for selecting the temperature is that the suitable temperature ranges for the above two types of silane coupling agent treatments are different, and in this temperature range, the functional groups contained in the silane coupling agent formed on the nodular-treated surface of the substrate and bonded to the substrate remain intact, and thus, the silane coupling agent can obtain sufficient adhesion to the surface of the copper foil.
The method as claimed in claim 5 or 7, which comprises drying the copper foil, treating the dried copper foil with a silane coupling agent, and further drying the treated copper foil, wherein the condensation reaction of the silane coupling agent on the chromate treatment layer consumes a large amount of heat supplied to the high temperature atmosphere during the drying. In contrast, in the method according to claim 6 or 8, the surface-treated copper foil is produced by the steps of: an electrolytic chromate layer is formed, washed with water, a silane coupling agent layer is formed without drying the surface to which the coupling agent is to be applied, and finally dried. Therefore, the copper foil needs to hold much water in the drying step as compared with the case of producing a surface-treated copper foil including the steps of sequentially forming a chromate layer, drying, forming a silane coupling agent layer, and drying again. In the heat drying process, considerable heat is consumed to evaporate water. Therefore, it is conceivable that even if the temperature of the drying atmosphere is raised to about 200 ℃, it is difficult to generate heat sufficient to destroy or decompose the functional groups of the silane coupling agent. So that the functional groups contained in the silane coupling agent layer and bonded to the substrate can be effectively prevented from being damaged, thereby improving the quality of the surface-treated copper foil product.
To confirm the above-mentioned belief, the copper foil of the present invention 1 or 2 having a thickness of 35 μm was obtained by drying at different temperatures for 4 seconds, and then laminated with FR-4, respectively, to give a copper-clad laminate. A wiring having a line width of 0.2mm was formed from this copper-clad laminate, and the peel strength of each copper-clad laminate was measured. The measurement results are shown in tables 1 to 4.
TABLE 1
| Drying temperature of copper foil | Peel-off test results (line width 0.2 mm) | |||
| Initial Peel Strength (kg/cm) | Peel strength (kg/cm) floating after solder bath | Hydrochloric acid resistance, peel strength loss (%) | Moisture resistance, loss of peel strength (%) | |
| 80 | 1.88 | 1.87 | 37.5 | 21.3 |
| 100 | 1.89 | 1.87 | 30.8 | 17.2 |
| 105 | 1.88 | 1.86 | 8.3 | 9.9 |
| 110 | 1.87 | 1.85 | 7.6 | 9.4 |
| 120 | 1.86 | 1.85 | 8.1 | 8.7 |
| 130 | 1.87 | 1.86 | 7.4 | 8.6 |
| 140 | 1.88 | 1.87 | 7.2 | 7.5 |
| 150 | 1.89 | 1.88 | 7.5 | 8.2 |
| 160 | 1.87 | 1.85 | 8.0 | 8.0 |
| 170 | 1.88 | 1.86 | 7.3 | 7.7 |
| 180 | 1.86 | 1.85 | 6.9 | 8.2 |
| 190 | 1.88 | 1.87 | 11.1 | 10.6 |
| 200 | 1.88 | 1.86 | 12.4 | 10.8 |
| 210 | 1.87 | 1.86 | 17.2 | 14.3 |
| 220 | 1.86 | 1.86 | 22.3 | 21.6 |
The copper foil used: a surface-treated copper foil (wherein no ultrafine copper particles are formed and the silane coupling agent treatment is carried out after drying) produced from the copper foil of claim 1 by the method of claim 5.
Initial peel strength: the copper-clad laminate was made of FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The peel strength between the copper wire and the substrate was measured.
Peel strength after floating in the solder bath: the wire with the copper foil pattern was floated on a solder bath (246 ℃ C.) for 20 seconds and then cooled to room temperature. The peel strength was measured.
Hydrochloric acid resistance (peel strength loss%): a copper-clad laminate was produced from FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in a solution of hydrochloric acid and water (1: 1) for one hour at room temperature, then removed from the solution, rinsed with water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
Moisture resistance (peel strength loss%): a copper-clad laminate was made of FR-4, and a copper pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in boiling deionized water (pure water) for two hours, then taken out of the water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
TABLE 2
| Drying temperature of copper foil | Peel-off test results (line width 0.2 mm) | |||
| Initial Peel Strength (kg/cm) | Peel strength (kg/cm) floating after solder bath | Hydrochloric acid resistance, peel strength loss (%) | Moisture resistance, loss of peel strength (%) | |
| 80 | 1.87 | 1.85 | 30.7 | 25.8 |
| 100 | 1.87 | 1.86 | 31.2 | 25.2 |
| 105 | 1.88 | 1.86 | 18.5 | 21.2 |
| 110 | 1.88 | 1.87 | 6.6 | 8.5 |
| 120 | 1.87 | 1.87 | 5.5 | 8.3 |
| 130 | 1.86 | 1.84 | 5.0 | 8.0 |
| 140 | 1.89 | 1.88 | 4.7 | 7.9 |
| 150 | 1.88 | 1.86 | 4.8 | 6.9 |
| 160 | 1.88 | 1.86 | 5.1 | 7.4 |
| 170 | 1.87 | 1.86 | 4.7 | 7.5 |
| 180 | 1.86 | 1.84 | 4.0 | 6.3 |
| 190 | 1.86 | 1.85 | 3.0 | 7.1 |
| 200 | 1.88 | 1.89 | 4.2 | 7.0 |
| 210 | 1.87 | 1.86 | 11.5 | 21.8 |
| 220 | 1.88 | 1.86 | 21.4 | 30.3 |
The copper foil used: the surface-treated copper foil produced by the method of claim 5 from the copper foil of claim 1 (wherein the ultrafine copper particles are not formed and the silane coupling agent treatment is carried out after drying).
Initial peel strength: the copper-clad laminate was made of FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The peel strength between the copper wire and the substrate was measured.
Peel strength after floating in the solder bath: the wire with the copper foil pattern was floated on a solder bath (246 ℃ C.) for 20 seconds and then cooled to room temperature. The peel strength was measured.
Hydrochloric acid resistance (peel strength loss%): a copper-clad laminate was produced from FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in a solution of hydrochloric acid and water (1: 1) for one hour at room temperature, then removed from the solution, rinsed with water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
Moisture resistance (peel strength loss%): a copper-clad laminate was made of FR-4, and a copper pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in boiling deionized water (pure water) for two hours, then taken out of the water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
TABLE 3
The copper foil used: the surface-treated copper foil produced by the method of claim 5 from the copper foil of claim 1 (wherein the ultrafine copper particles are not formed and the silane coupling agent treatment is carried out after drying).
| Drying temperature of copper foil | Peel-off test results (line width 0.2 mm) | |||
| Initial Peel Strength (kg/cm) | Peel strength (kg/cm) floating after solder bath | Hydrochloric acid resistance, peel strength loss (%) | Moisture resistance, loss of peel strength (%) | |
| 80 | 1.88 | 1.87 | 30.0 | 27.0 |
| 100 | 1.88 | 1.88 | 22.6 | 14.3 |
| 105 | 1.88 | 1.87 | 8.7 | 7.5 |
| 110 | 1.88 | 1.87 | 6.8 | 7.4 |
| 120 | 1.87 | 1.85 | 7.2 | 6.7 |
| 130 | 1.89 | 1.87 | 7.4 | 7.3 |
| 140 | 1.88 | 1.88 | 6.9 | 7.3 |
| 150 | 1.87 | 1.88 | 6.0 | 7.2 |
| 160 | 1.88 | 1.87 | 6.6 | 6.8 |
| 170 | 1.87 | 1.86 | 7.0 | 6.4 |
| 180 | 1.88 | 1.87 | 6.3 | 6.1 |
| 190 | 1.89 | 1.87 | 10.5 | 18.6 |
| 200 | 1.87 | 1.88 | 12.7 | 21.8 |
| 210 | 1.88 | 1.87 | 16.8 | 24.7 |
| 220 | 1.87 | 1.86 | 23.3 | 28.7 |
Initial peel strength: the copper-clad laminate was made of FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The peel strength between the copper wire and the substrate was measured.
Peel strength after floating in the solder bath: the wire with the copper foil pattern was floated on a solder bath (246 ℃ C.) for 20 seconds and then cooled to room temperature. The peel strength was measured.
Hydrochloric acid resistance (peel strength loss%): a copper-clad laminate was produced from FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in a solution of hydrochloric acid and water (1: 1) for one hour at room temperature, then removed from the solution, rinsed with water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
Moisture resistance (peel strength loss%): a copper-clad laminate was made of FR-4, and a copper pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in boiling deionized water (pure water) for two hours, then taken out of the water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
TABLE 4
| Drying temperature of copper foil | Peel-off test results (line width 0.2 mm) | |||
| Initial Peel Strength (kg/cm) | Peel strength (kg/cm) floating after solder bath | Hydrochloric acid resistance, peel strength loss (%) | Moisture resistance, loss of peel strength (%) | |
| 80 | 1.89 | 1.87 | 39.7 | 26.3 |
| 100 | 1.88 | 1.87 | 28.6 | 25.3 |
| 105 | 1.89 | 1.88 | 19.2 | 21.5 |
| 110 | 1.89 | 1.88 | 2.6 | 6.8 |
| 120 | 1.88 | 1.87 | 1.7 | 5.4 |
| 130 | 1.87 | 1.87 | 1.7 | 5.2 |
| 140 | 1.89 | 1.88 | 1.2 | 6.0 |
| 150 | 1.88 | 1.86 | 1.3 | 5.9 |
| 160 | 1.87 | 1.86 | 0.0 | 5.5 |
| 170 | 1.88 | 1.87 | 1.0 | 6.3 |
| 180 | 1.87 | 1.87 | 0.0 | 5.0 |
| 190 | 1.89 | 1.87 | 0.8 | 4.1 |
| 200 | 1.89 | 1.88 | 1.4 | 4.7 |
| 210 | 1.88 | 1.87 | 14.7 | 19.8 |
| 220 | 1.87 | 1.86 | 22.1 | 24.6 |
The copper foil used: a surface-treated copper foil (wherein no ultrafine copper particles are formed and the silane coupling agent treatment is carried out after drying) produced from the copper foil of claim 1 by the method of claim 5.
Initial peel strength: the copper-clad laminate was made of FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The peel strength between the copper wire and the substrate was measured.
Peel strength after floating in the solder bath: the wire with the copper foil pattern was floated on a solder bath (246 ℃ C.) for 20 seconds and then cooled to room temperature. The peel strength was measured.
Hydrochloric acid resistance (peel strength loss%): a copper-clad laminate was produced from FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in a solution of hydrochloric acid and water (1: 1) for one hour at room temperature, then removed from the solution, rinsed with water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
Moisture resistance (peel strength loss%): a copper-clad laminate was made of FR-4, and a copper pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in boiling deionized water (pure water) for two hours, then taken out of the water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
It is clear from tables 1 to 4 that there is not much difference between the initial peel strength of the sample and the peel strength after floating in the flux bath. However, the hydrochloric acid resistance and the moisture resistance thereof vary greatly in response to certain temperatures, and a suitable drying temperature range is seen. The surface-treated copper foil obtained by drying in this temperature range has not so far achieved excellent and stable hydrochloric acid resistance (peel strength loss (%)) and moisture resistance (peel strength loss (%)). The hydrochloric acid resistance (peel strength loss (%)) is an index representing the loss of the peel strength of the copper foil from the initial peel strength thereof by the hydrochloric acid treatment listed in each table. The measurement of the initial peel strength was performed immediately after the tested line pattern was formed on the copper foil. The hydrochloric acid resistance was calculated from the following formula:
[ hydrochloric acid resistance (peel strength loss (%) ] ([ initial peel strength after immersion in a hydrochloric acid solution) ]/[ initial peel strength ] [ peel strength loss (%) ]. moisture resistance [ peel strength loss (%) ], which is an index showing the loss of the peel strength of the copper foil from the moisture adsorption treatment with respect to the initial peel strength thereof listed in each table.
[ moisture resistance (peel strength loss (%) ] ([ initial peel strength ] - [ peel strength after boiling water treatment ])/[ initial peel strength ].
Further, a comparison of tables 1 and 2 and a comparison of tables 3 and 4 show that the surface-treated copper foil obtained by subjecting the electrolytically chromate-treated copper foil to a treatment with a silane coupling agent without drying the copper foil has a better hydrochloric acid resistance and moisture resistance than the surface-treated copper foil obtained by drying the electrolytically chromate-treated copper foil and then treating the dried electrolytically chromate-treated copper foil with a silane coupling agent.
Comparison of tables 1 and 2 and comparison of tables 3 and 4 also found that, when the copper foil is produced by first drying the copper foil and then treating it with a silane coupling agent, the copper foil itself falls within a suitable drying temperature (in the tables, the temperature means the copper foil temperature) of 105 ℃ to 180 ℃ in the range where the copper foil has excellent hydrochloric acid resistance and moisture resistance; however, when the copper foil is prepared by treating the copper foil with a silane coupling agent without drying, the suitable temperature of the copper foil itself falls within the range of 110 ℃ to 200 ℃, and in this range, the copper foil has excellent hydrochloric acid resistance and moisture resistance. In the latter case, the temperature of the copper foil can be adjusted to be slightly higher than that in the former case. Accordingly, it is considered that when the temperature of the copper foil is lower than the lower limit of each of the two temperature ranges, the adhesion of the silane coupling agent to the copper foil is poor, resulting in poor adhesion to the substrate. Meanwhile, it is also considered that when the copper foil temperature exceeds the upper limit, the functional group of the silane coupling agent bonded to the substrate is destroyed or decomposed, causing poor adhesion to the substrate, thus lowering hydrochloric acid resistance and moisture resistance thereof (increasing the reduction percentage of peel strength thereof).
Further comparing tables 1 and 3 and tables 2 and 4, it was found that the copper foil obtained by forming extremely fine copper particles after the seal plating in the nodular treatment process had high hydrochloric acid resistance and moisture resistance. It is considered that the anchor effect produced by the nodular surface of the surface-treated copper foil is increased, and the adhesion to the substrate is improved.
As described above, the surface-treated copper foil of the present invention was produced. The copper-clad laminate made of the copper foil obtained by the above method has excellent and stable hydrochloric acid resistance and moisture resistance. Thus, as described in claim 10, the copper-clad laminate made of the surface-treated copper foil described in any one of claims 1 to 4 can be improved in quality to a large extent and provide high reliability in etching.
In the present specification, the "copper-clad laminate" includes a single-sided substrate, a double-sided substrate, and a multi-sided substrate. These substrates may be rigid, flexible or composite substrates, including specialty substrates such as TAB or COB.
Detailed Description
Some embodiments of the invention are described below in conjunction with fig. 1, 2, and 3. The surface-treated copper foil 1 produced according to the present invention and the method of producing a copper-clad laminate made of this surface-treated copper foil 1, and the evaluation results thereof will be described in the following examples. The copper foil 2 in all the following examples is referred to as an electrolytic copper foil.
Example 1
In example 1, the copper foil 2 was surface-treated with a surface treatment apparatus 3. Before the surface treatment, the copper foil 2 used is rolled up. The copper foil 2 is unwound from the foil roll and is wound to run in a surface treatment apparatus 3 shown in fig. 2. Copper foil 2 was a grade 3 copper foil having a nominal thickness of 35 μm, resulting in an electrolytic copper foil for printed wiring boards. The conditions of production will be described hereinafter in connection with an apparatus in which a number of grooves are arranged in a line in succession. This example will be described with reference to FIG. 1(a), which shows a cross-sectional view of a surface-treated copper foil.
First, the copper foil 2 obtained from a roll is transferred to an acid bath 4 containing a dilute sulfuric acid solution having a concentration of 150g/l at 30 ℃. The copper foil was immersed for 30 seconds to remove the oily substance and the surface oxide film on the surface of the copper foil 2.
After the copper foil 2 is treated in the pickling tank 4, the copper foil is transferred to the nodular treatment tank 6, and fine copper particles 5 are formed on the surface of the copper foil 2. The treatment performed in the nodular treatment bath 6 includes deposition of fine copper particles 5 on one surface of the copper foil 2 (step 6A) and seal plating (step 6B), the latter step being for preventing the fine copper particles 5 from falling off. In this case, the copper foil 2 is negatively polarized and a suitable anode 7 is provided for the electrolysis. For example, when the copper foil 2 is subjected to nodular treatment to form a double-sided treated copper foil, one more anode 7 is placed on each side of the copper foil 2.
Step 6A-depositing fine copper particles on the surface of the copper foil 2-Using a copper sulfate solution (sulfuric acid concentration 100/l, copper concentration 18g/l, temperature 25 ℃ C.), under conditions to form a burn-out deposit at 10A/m2The current density of (2) was subjected to electrolysis for 10 seconds. In this case, the anode plate is placed in parallel with the surface of the copper foil 2 on which fine copper particles are to be formed, facing each other, as shown in fig. 2.
Step 6B-performing seal plating to prevent the fine copper particles 5 from falling off-using a copper sulfate solution (sulfuric acid concentration of 150g/l, copper concentration of 65g/l, temperature of 45 ℃ C.) at 15A/m under seal plating conditions2The plating was carried out for 20 seconds at the current density of (2) to form a closed plating layer. In this case, the anode plate 7 is placed as shown in parallel with the surface of the copper foil 2 on which the fine copper particles (5) are deposited facing each other. The anode 7 is made of stainless steel.
The corrosion-resistant treatment by electroplating of a zinc-copper-nickel ternary alloy is performed in a ternary alloy corrosion-resistant treatment tank 9. This step uses the procedure shown in FIG. 2The zinc concentration in the ternary alloy corrosion-resistant treatment tank 9 is maintained using zinc pyrophosphate, copper pyrophosphate, and nickel pyrophosphate. The electrolysis was carried out in a pyrophosphate solution of controlled concentration, containing zinc (15g/l), copper (10g/l) and nickel (3g/l), at an electrolysis temperature of 40 ℃ and a current density of 15A/m2The time was 8 seconds.
The corrosion resistance treatment by the electrolytic chromate treatment is performed in the chromate-corrosion resistance treatment bath 10, and a chromate layer is electrolytically formed on the formed ternary alloy electroplated corrosion resistance layer. The electrolysis was carried out in a solution containing 5.0g/l of chromic acid at 35 deg.C, pH 11.5 and current density 8A/m2The time was 5 seconds. In this case, the anode plate 7 is placed in parallel face-to-face relation with the surface of the copper foil as shown.
After the completion of the corrosion-resistant treatment, the copper foil is washed with water and the adsorption of the silane coupling agent is carried out immediately without drying the surface of the copper foil in the silane coupling agent treatment tank 11, and the silane coupling agent is adsorbed on the corrosion-resistant layer of the nodular-treated surface of the copper foil. The solution used was prepared by dissolving gamma-glycidoxypropyltrimethoxysilane in deionized water. The solution was sprayed onto the copper foil surface by a sprayer.
After the completion of the silane coupling agent treatment, the copper foil 2 is passed through a heating furnace including a drying tube 12 within 4 seconds, and the atmosphere in the drying tube 12 is adjusted by an electric heater 13 to bring the copper foil to a temperature of 140 ℃ to accelerate the condensation reaction of the silane coupling agent. This surface-treated copper foil 1 which has been dehydrated is then wound into a roll. In all the above steps, the copper foil was conveyed at a speed of 2.0 m/min. A rinsing bath 14 capable of water washing for about 15 seconds may also be installed between the above-mentioned series of operation baths to prevent the solution of the previous bath from being carried to the next bath.
The surface-treated copper foil 1 thus formed was laminated with two sheets of FR-4 prepreg as a base material, the FR-4 prepreg having a thickness of 150 μm, to obtain a copper-clad double laminate. The peel strength at the bonding interface of the surface-treated copper foil 1 and the substrate was measured. Each sample was measured at 7 points, and the results are shown in table 5.
Example 2
In example 2, the copper foil 2 was surface-treated with the surface treatment apparatus 3. Before the surface treatment, the copper foil 2 used is wound. The copper foil 2 is unwound from the foil roll and runs in a wound manner in a surface treatment apparatus 3 as shown in fig. 3. Copper foil 2 was a grade 3 copper foil having a nominal thickness of 35 μm, resulting in an electrolytic copper foil for use in printed wiring boards. The conditions of production will be described below in connection with an apparatus in which a number of grooves are arranged in a line. To avoid redundant description, only portions different from the corresponding portions in embodiment 1 are described. Wherever possible, the same parts as in embodiment 1 are denoted by the same numerals in fig. 3. This embodiment will be described with reference to FIG. 1(b), which is a sectional view of a surface-treated copper foil.
The surface treatment flow of example 2 was the same as that of example 1 except that the nodularization treatment performed in the groove 6 included 3 steps. The nodularization treatment in example 2 includes a step 6A of depositing fine copper particles 5, a step 6B of close plating, and a step 6C of depositing extremely fine copper particles 15. In short, the step 6C of depositing very fine copper particles is arranged between the closed plating step 6B performed in example 1 and the ternary alloy corrosion-resistant treatment step performed in the bath 9.
Step 6C-precipitation of very fine copper particles 15-Electrolysis at 30A/m/L using a copper sulfate solution (copper concentration 10g/l, sulfuric acid concentration 100g/l, 9-phenylacridine concentration 140mg/l, temperature 38 ℃ C.)2Is carried out at a current density of (1). The other processing steps performed in each tank were the same as those of example 1.
The surface-treated copper foil 1 thus produced was laminated with two sheets of FR-4 prepreg as a base material, the thickness of which was 150 μm, to obtain a copper-clad double-sided laminate. The peel strength at the bonding interface between the surface-treated copper foil 1 and the substrate was measured. The results of example 1 and example 2 are shown in table 5 at 7 for each sample measurement.
TABLE 5
| Sample (I) | Peel test results (line width 0.2 mm) | ||||
| Initial Peel Strength (kg/cm) | Peel strength (kg/cm) floating after solder bath | Hydrochloric acid resistance, peel strength loss (%) | Moisture resistance, loss of peel strength (%) | ||
| Example 1 | 1 | 1.87 | 1.86 | 3.6 | 8.5 |
| 2 | 1.86 | 1.86 | 3.5 | 8.3 | |
| 3 | 1.87 | 1.86 | 4.0 | 8.7 | |
| 4 | 1.88 | 1.87 | 3.8 | 8.1 | |
| 5 | 1.87 | 1.86 | 3.7 | 8.9 | |
| 6 | 1.86 | 1.86 | 3.2 | 9.0 | |
| 7 | 1.87 | 1.87 | 3.5 | 8.4 | |
| Example 2 | 1 | 1.88 | 1.87 | 0.2 | 6.7 |
| 2 | 1.89 | 1.87 | 1.0 | 7.0 | |
| 3 | 1.88 | 1.87 | 0.8 | 7.2 | |
| 4 | 1.87 | 1.86 | 0.0 | 6.3 | |
| 5 | 1.88 | 1.87 | 0.0 | 6.5 | |
| 6 | 1.87 | 1.87 | 0.1 | 7.0 | |
| 7 | 1.88 | 1.86 | 0.6 | 6.1 | |
The copper foil used: a surface-treated copper foil (wherein no ultrafine copper particles are formed and the silane coupling agent treatment is carried out after drying) produced from the copper foil of claim 1 by the method of claim 5.
Peel strength after floating in the solder bath: the wire with the copper foil pattern was floated on a solder bath (246 ℃ C.) for 20 seconds and then cooled to room temperature. The peel strength was measured.
Hydrochloric acid resistance (peel strength loss%): a copper-clad laminate was produced from FR-4, and a copper foil pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in a solution of hydrochloric acid and water (1: 1) for one hour at room temperature, then removed from the solution, rinsed with water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
Moisture resistance (peel strength loss%): a copper-clad laminate was made of FR-4, and a copper pattern having a line width of 0.2mm was formed on the FR-4. The plate was immersed in boiling deionized water (pure water) for two hours, then taken out of the water and dried. The peel strength of the wiring board was measured immediately after drying. The percent loss of this peel strength compared to the initial peel strength was calculated.
As is clear from table 5, the copper foil pattern made of the surface-treated copper foil 1 of example 1 or 2 had hydrochloric acid resistance and moisture resistance of 10% (percent loss of peel strength) or less even if its line width was 0.2 mm. Specifically, the loss of peel strength against hydrochloric acid energy is 5% or less, which is excellent. In at least 10 batches of the copper laminate product obtained in a similar manner to example 1 or 2, the difference in the hydrochloric acid resistance and moisture resistance measured between the batches was quite small. Therefore, the copper foil of the present invention has unprecedented high and stable quality as compared with the conventional copper foil, and the quality of a printed wiring board can be greatly improved.
Effects of the invention
The surface treatment copper foil can greatly improve the adhesion reliability of the base material on the printed circuit board and the circuit obtained by the copper foil in the etching step; enabling the use of a wide variety of methods for producing printed wiring boards; and makes control of the production steps easier. In addition, the method for producing a surface-treated copper foil of the present invention can provide a surface-treated copper foil having excellent hydrochloric acid resistance and moisture resistance since the silane coupling agent adsorbed thereon exerts the greatest effect.
Claims (10)
1. A surface-treated copper foil for producing a printed wiring board, the surface of which is subjected to a nodular treatment and an anti-corrosion treatment, characterized in that the anti-corrosion treatment comprises forming a zinc-copper-nickel ternary alloy plating layer on the surface of the copper foil; forming an electrolytic chromate layer on the zinc-copper-nickel ternary alloy electroplated layer; forming a silane coupling agent adsorption layer on the electrolytic chromate layer; the copper foil is dried for 2-6 seconds at a temperature of 105 deg.C-200 deg.C.
2. A surface-treated copper foil for producing a printed wiring board, the surface of which is subjected to a nodular treatment comprising depositing fine copper particles on the surface of the copper foil; carrying out closed electroplating to prevent the shedding of the fine copper particles; depositing active fine copper particles; the anti-corrosion treatment comprises forming a zinc-copper-nickel ternary alloy electroplated layer on the surface of the copper foil; forming an electrolytic chromate layer on the zinc-copper-nickel ternary alloy electroplated layer; forming a silane coupling agent adsorption layer on the electrolytic chromate layer; drying the copper foil for 2-6 seconds at 105-200 deg.C.
3. The surface-treated copper foil as set forth in claim 1 or 2, wherein the zinc-copper-nickel ternary alloy plating layer comprises 69.9-20% by weight of zinc, 30-70% by weight of copper and 0.1-10% by weight of nickel.
4. The surface-treated copper foil according to any one of claims 1 to 3, wherein the silane coupling agent is selected from the group consisting of an olefin group-functional silane, an epoxy group-functional silane, an acrylic group-functional silane, an amino-functional silane, and a mercapto-functional silane.
5. A method for producing the surface-treated copper foil of any one of claims 1, 3 and 4, which is used for producing a printed wiring board, comprising a surface treatment method comprising forming a nodular-treated surface on a copper foil; carrying out corrosion resistance treatment on the copper foil; adsorbing a silane coupling agent onto the nodular treated surface; then drying, wherein the anti-corrosion treatment comprises electroplating of a zinc-copper-nickel ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; then drying the surface of the copper foil; adsorbing the silane coupling agent; drying the copper foil in a high-temperature atmosphere for 2-6 seconds, wherein the temperature of the copper foil reaches 105-180 ℃ during drying.
6. A method for producing the surface-treated copper foil of any one of claims 1, 3 and 4, which is used for producing a printed wiring board, comprising a surface treatment method comprising forming a nodular-treated surface on a copper foil; carrying out corrosion resistance treatment on the copper foil; adsorbing a silane coupling agent onto the nodular treated surface; then drying, wherein the anti-corrosion treatment comprises electroplating of a zinc-copper-nickel ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; adsorbing the silane coupling agent without drying the electrolytically chromated surface; drying the copper foil in a high-temperature atmosphere for 2-6 seconds, wherein the temperature of the copper foil reaches 110-200 ℃ during drying.
7. A method for producing the surface-treated copper foil claimed in any one of claims 2 to 4, comprising a surface treatment method comprising forming a nodular-treated surface on a copper foil; carrying out corrosion resistance treatment on the copper foil; adsorbing a silane coupling agent onto the nodular treated surface; then drying, wherein the nodularization treatment comprises the deposition of fine copper particles on the surface of the copper foil; carrying out closed electroplating to prevent the shedding of the fine copper particles; depositing active fine copper particles, wherein the anti-corrosion treatment comprises electroplating zinc-copper-nickel-ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; drying the surface of the copper foil; adsorbing a silane coupling agent; the copper foil is dried in an atmosphere of high temperature, in which the temperature of the copper foil reaches 105 ℃ to 180 ℃, for 2 to 6 seconds.
8. A method for producing the surface-treated copper foil claimed in any one of claims 2 to 4, comprising a surface treatment method comprising forming a nodular-treated surface on a copper foil; carrying out corrosion resistance treatment on the copper foil; adsorbing a silane coupling agent onto the nodular treated surface; then drying, wherein the nodularization treatment comprises the deposition of fine copper particles on the surface of the copper foil; carrying out closed electroplating to prevent the shedding of the fine copper particles; depositing active fine copper particles; the anti-corrosion treatment comprises the steps of electroplating zinc-copper-nickel-ternary alloy on the surface of the copper foil; then carrying out electrolytic chromate treatment; adsorbing the silane coupling agent without drying the electrolytically chromated surface; drying the copper foil in a high temperature atmosphere in which the temperature of the copper foil reaches 110 ℃ to 200 ℃.
9. A method for producing the surface-treated copper foil claimed in any one of claims 7 or 8, wherein the ultrafine copper particles are formed using an electrolytic solution containing a copper component to which 9-phenylacridine is added.
10. A copper-clad laminate produced from the surface-treated copper foil claimed in any one of claims 1 to 4.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP020884/00 | 2000-01-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| HK1047854A true HK1047854A (en) | 2003-03-07 |
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