TW202042600A - Copper foil with surface treatment, copper-coated laminate, and printed circuit board capable of achieving tightness with non-roughened surface and reliability of high standard and reduced transmission loss - Google Patents

Abstract

The present invention provides a copper foil with surface treatment, which may achieve tightness with non-roughened surface and reliability of high standard and reduced transmission loss. The copper foil with surface treatment includes: a copper foil body 1, wherein one of the two main surfaces is a roughed surface 1a formed by a roughening process, and the other one is a non-roughened surface 1b; and, an anti-rust layer 10 formed on the non-roughened surface 1b of the copper foil body 1. The anti-rust layer 10 includes a metal zinc layer 11 composed of metal zinc, a zinc oxide layer 12 composed of zinc oxide, a zinc hydroxide layer 13 composed of zinc hydroxide, and a chromate layer 14 composed of chromium compound. Each layer of the anti-rust layer 10 is sequentially laminated from the copper foil body 1 as metal zinc layer 11, zinc oxide layer 12, zinc hydroxide layer 13, and chromate layer 14.

Description

Surface treatment copper foil, copper clad laminate and printed circuit board

The invention relates to a surface-treated copper foil. Furthermore, the present invention relates to a copper-clad laminate and printed wiring board using the aforementioned surface-treated copper foil.

In various electronic devices, printed circuit boards are used as substrates and connecting materials, and the conductive layer of the printed circuit boards usually uses copper foil. As the copper foil used for printed wiring boards, rolled copper foil and electrolytic copper foil are usually used.

For rolled copper foil used as copper foil for printed wiring boards, in order to suppress crystal growth due to the thermal history imparted in the manufacturing process, additives such as metals are contained as essential components. Therefore, there are situations in which the original conductivity of copper foil is reduced, and in addition, the manufacturing cost is higher than that of electrolytic copper foil. Therefore, as copper foils for printed wiring boards, there is a tendency to widely use electrolytic copper foils with high conductivity, excellent productivity, and easy thinning.

In recent years, with the further increase of mobile communication traffic, etc., the transmission of high frequency signals from several GHz to 100 GHz on printed circuit boards has increased. It is known that the high-frequency signal has the following tendency: the higher the frequency, the more high-speed and large-capacity communication is possible. On the other hand, the signal only passes through the surface of the conductive layer of the printed circuit board (skin effect). If the high frequency signal only passes through the surface, it will be more affected by the surface shape of the copper foil and the anti-rust layer. That is, if the surface roughness of the copper foil is large, the transmission length of the signal becomes large, and the transmission loss becomes large. In addition, if the conductivity is lower than that of copper or there are more dissimilar metals with magnetism on the surface of the copper foil, the transmission loss will increase. Therefore, from the viewpoint of reducing transmission loss, the smoother the surface of the copper foil and the smaller the roughness, the better, and the smaller the amount of adhesion of dissimilar metals, the better.

On the other hand, in general, a printed wiring board is manufactured by laminating a resin film containing epoxy resin, polyphenylene ether, etc., and copper foil by high-temperature pressing, and forming a circuit pattern by etching. Therefore, in order to improve the adhesion to the resin film, a roughening treatment layer is often provided on the surface of the copper foil. The so-called roughening treatment is to adjust the surface shape of the copper foil (including the shape of the granular protrusions made of copper or various alloys, and the porous shape obtained by etching the copper foil) to increase the roughness.

In addition, as the reliability of printed wiring boards, it is necessary to maintain good adhesion between the copper foil and resin during heating (for example, heat resistance test) and acid immersion (for example, acid immersion test). Therefore, copper Most of the foils are provided with anti-rust layers containing dissimilar metals represented by nickel, zinc, and chromium.

However, from the viewpoint of reducing transmission loss, these roughened layers and anti-rust layers become the main cause of adverse effects. Based on this situation, a lot of research has been conducted so far in order to balance the adhesion, reliability, and reduction of transmission loss.

For example, Patent Document 1 proposes a technique for increasing the surface area of copper foil by using fine concavities and convexities. Patent Document 2 proposes a technique for forming roughened particles into a special shape. Patent Document 3 proposes the use of The technology of forming fine roughened particles with alloy plating of nickel, cobalt, etc. In Patent Document 4, it is proposed to form fine roughened particles and cover the roughened particles with an anti-oxidation treatment layer containing molybdenum and cobalt On the technology.

Based on the above facts, in recent years, a higher level of adhesion, reliability, and reduction of transmission loss have been required. Based on this, research on the non-roughened surface of copper foil is underway.

In addition, in this specification, the surface of the copper foil having the roughened layer is referred to as the "roughened surface", and the surface without the roughened layer is referred to as the "non-roughened surface". The non-roughened surface of the electrolytic copper foil has a shape (shiny surface, hereinafter referred to as "S surface") transferred with the grinding traces of the drum surface as the cathode according to the manufacturing method, or it is in contact with the electrolyte, Any of the plating precipitation shapes (mat surface, hereinafter referred to as "M surface") corresponding to various organic additives. The non-roughened surface of rolled copper foil becomes the finished surface shape of rolling.

When manufacturing multilayer printed wiring boards, similar to the roughened surface, the non-roughened surface also requires adhesion and reliability to the resin film (that is, the adhesion between the copper foil and the resin during heating and acid immersion) ). In addition, in this specification, the adhesion and reliability of the copper foil to the resin film on the non-roughened surface (the adhesion between the copper foil and the resin during acid immersion when heated) is described as the non-roughness of the copper foil The "inner adhesion" of the face.

After the circuit pattern is made, the non-roughened surface of the copper foil is half-etched as needed. In order to improve the adhesion of the inner layer, the non-roughened surface of the copper foil and the etched end surface of the circuit pattern are blackened, micro-etched, etc. Internal treatment. Blackening treatment is a method of forming copper oxides and copper protrusion shapes obtained by reducing copper oxides. Micro-etching is made by dissolving the copper foil into a porous shape by using a treatment solution of sulfuric acid-hydrogen peroxide and organic acid. The method of roughening the surface. However, no matter which method is used, the roughness of the copper foil surface is increased, which becomes one of the main reasons for increasing transmission loss.

In addition, there are also cases where the chemical adhesion treatment represented by GliCAP of Shikoku Chemical Industry Co., Ltd., which does not increase the surface roughness of the copper foil, is used as the inner layer treatment, but the inner layer has poor adhesion And the effect of improving the adhesion of the inner layer varies greatly depending on the type of resin attached.

The increase in the roughness of the non-roughened surface caused by the inner layer treatment and the increase in the transmission loss accompanying it are phenomena that have been recognized since the beginning. However, in the previous copper foil, since the roughened surface has a greater impact on the increase in transmission loss compared to the non-roughened surface, the improvement of the non-roughened surface is not increased. In recent years, with the improvement and development of roughening surface, the impact of non-roughening surface increased by the increase in transmission loss has become greater. In this process, a higher level of adhesion, reliability and transmission is required than before. The reduction of loss, the improvement of non-roughened surface has gradually attracted attention.

For example, Non-Patent Document 1 discloses that by using micro-etching as an inner layer treatment, in particular, the transmission loss will increase, and the higher the signal, the more noticeable its influence will be. On the other hand, the report states: In order to ensure the adhesion of the inner layer, micro-etching is necessary.

In addition, Patent Document 5 discloses a method of performing surface treatment using tin, nickel, or any of these alloys as an inner layer treatment instead of blackening treatment, and then applying a primer resin. Prior art literature Patent literature

Patent Document 1: Japanese Patent No. 6182584 Patent Document 2: Japanese Patent No. 5972486 Patent Document 3: Japanese Patent Laid-Open No. 2015-61939 Patent Document 4: Japanese Patent No. 6083619 Patent Document 5: Japanese Patent No. 5129843 Patent Document 6: Japanese Patent No. 6182584 Non-patent literature

Non-Patent Document 1: Sugimoto Kaoru et al., "The Effect of Surface Roughness of Conductors in Multilayer Printed Wiring Boards on High-speed Transmission", Surface Technology, Surface Technology Association, 2018, Vol. 69, No. 1, p. 38–45

[Problems to be Solved by the Invention] As described above, the current situation is a trade-off for the reduction of the inner layer adhesion and transmission loss of the non-roughened surface of copper foil, and copper foil that meets the high level of demand in recent years cannot be obtained. The use of magnetic metals such as nickel as the inner layer treatment will result in a significant increase in transmission loss. Not only does the properties of the primer resin affect the transmission loss, but also the manufacturing cost significantly increases.

In fact, the status quo is to sacrifice any characteristic while performing trial and error according to the type of resin attached and the customer's manufacturing process: the optimization of the previous inner layer treatment; the previous non-roughening of the copper foil Optimization of shape and anti-rust layer.

The subject of the present invention is to provide a surface-treated copper foil, a copper-clad laminate and a printed circuit board that have a high level of adhesion, reliability, and reduction of transmission loss on a non-roughened surface.

[Technical Means to Solve the Problem] The surface-treated copper foil of one aspect of the present invention is the following surface-treated copper foil, which is provided with a copper foil body, one of which is a roughened surface formed by roughening treatment. The other is a non-roughened surface; and an anti-corrosion layer is formed on the non-roughened surface of the copper foil body; the main purpose of the surface-treated copper foil is that the anti-rust layer has metallic zinc composed of metallic zinc Layer, zinc oxide layer composed of zinc oxide, zinc hydroxide layer composed of zinc hydroxide, and chromate layer composed of chromium compound. The anti-rust layer has these layers from the copper foil main body side It is laminated in the order of metallic zinc layer, zinc oxide layer, zinc hydroxide layer, and chromate layer.

The main purpose of another aspect of the copper-clad laminated board of the present invention is that it is provided with the surface-treated copper foil of the above-mentioned aspect and a resin-made substrate laminated on the roughened surface side of the surface-treated copper foil.

The main purpose of another aspect of the printed circuit board of the present invention is that it is provided with the above-mentioned another aspect of the copper clad laminate.

[Effects of the Invention] According to the present invention, the adhesion, reliability, and transmission loss of the non-roughened surface can be reduced at a high level.

An embodiment of the present invention will be described. In addition, this embodiment is an example of this invention, and various changes or improvements can be added to this embodiment, and the form which added various changes or improvements can also be included in this invention.

In order to solve the above-mentioned problems, the inventors of the present invention paid attention to the anti-rust layer of the non-roughened surface of the copper foil. Previously, electrogalvanization was usually performed on the non-roughened surface of the copper foil, and then one or both of acid chromate treatment and alkaline chromate treatment were performed. Regarding the rust-preventing layer formed in this way, it is suggested that in addition to the chromate component and metallic zinc, it contains a part of zinc hydroxide and zinc oxide, but it is extremely small. In addition, the inventors realized that metallic zinc is used as a parent phase to disperse In the form of zinc hydroxide, zinc oxide.

Based on this, the inventors of the present invention conducted intensive studies, and found that: the rust preventive layer having a chromate layer, a zinc hydroxide layer, a zinc oxide layer, and a metal zinc layer is formed according to the metal The zinc layer, zinc oxide layer, zinc hydroxide layer, and chromate layer are arranged in order to achieve a very high level of both the adhesion of the inner layer and the reduction of transmission loss.

That is, the surface-treated copper foil of this embodiment is the following surface-treated copper foil, which is provided with a copper foil body, one of its two main surfaces is a roughened surface formed by roughening treatment, and the other is a non- Roughened surface; and an anti-rust layer formed on the non-roughened surface of the copper foil body. Furthermore, the anti-corrosion layer has a metallic zinc layer composed of metallic zinc, a zinc oxide layer composed of zinc oxide, a zinc hydroxide layer composed of zinc hydroxide, and a chromate layer composed of a chromium compound, The layers of the rust preventive layer are laminated in the order of the metal zinc layer, the zinc oxide layer, the zinc hydroxide layer, and the chromate layer from the copper foil main body side.

In addition, the anti-rust layer may consist of only these four layers, or may have other layers together with the four layers.

In addition, the metallic zinc layer, zinc oxide layer, and zinc hydroxide layer sometimes contain unavoidable impurities together with metallic zinc, zinc oxide, and zinc hydroxide, respectively. As the unavoidable impurities contained in these layers, for example, lead, iron, cadmium, tin, chlorine, or these compounds can be cited. The chromate layer sometimes contains unavoidable impurities together with the chromium compound.

In addition, the zinc oxide layer and the zinc hydroxide layer sometimes contain indeterminate compounds of zinc oxide and zinc hydroxide, respectively.

Hereinafter, an example of the surface-treated copper foil of this embodiment will be described in detail with reference to FIG. 1. Immediately above the non-roughened surface 1b side of the copper foil main body 1, a metal zinc layer 11 is first provided. The metallic zinc layer 11 is a base metal, so it plays the role of sacrificing corrosion resistance and inhibiting the corrosion of other metals in contact. In addition, it is effective in preventing the decrease in adhesion during acid immersion.

Then, a zinc oxide layer 12 is provided directly above the metal zinc layer 11. Zinc oxide is composed of zinc oxide (ZnO), for example. It is believed that ZnO has a wurtzite structure with high ion binding properties, forming a dense layer. It is found that the zinc oxide layer 12 covering the lower metal zinc layer 11 can effectively prevent the decrease in adhesion during the heat resistance test and the acid immersion test.

In addition, the higher the heating temperature and the longer the heating time applied to the printed circuit board, the more the metal zinc will diffuse into the copper of the copper foil body 1 to form a copper-zinc alloy, which will damage the appearance of the color tone and adhesion. It was found that zinc oxide and copper do not diffuse into each other, so by having the zinc oxide layer 12, the adverse effects caused by the formation of the copper-zinc alloy can be suppressed to a minimum.

Then, a zinc hydroxide layer 13 is provided directly above the zinc oxide layer 12. The zinc hydroxide is, for example, zinc hydroxide (Zn(OH) ₂ ). Zn(OH) ₂ is a gel-like substance containing water molecules, and it has been found that it has the effect of making the chromate film (chromate layer 14) adhere more uniformly and firmly in the subsequent chromate treatment.

Then, a chromate layer 14 is provided directly above the zinc hydroxide layer 13. The chromate layer 14 is an anti-corrosion film composed of chromium oxide and hydroxide. The chromium oxide and hydroxide are carried out in an acidic or alkaline treatment solution containing chromium (VI) ions. It is formed by cathode electrolysis or simple impregnation. The chromate layer 14 serves as a bonding point with the functional group of the resin, especially the polyphenylene ether-based resin, improves the adhesion and effectively prevents the decrease in the adhesion during the heat resistance test and the acid immersion test. It is found that by the presence of the zinc hydroxide layer 13 in the lower layer, a denser and uniform chromate layer 14 can be formed than before.

As mentioned above, the rust-preventing layer 10 composed of the chromate layer 14/zinc hydroxide layer 13/zinc oxide layer 12/metal zinc layer 11 is provided on the copper foil body 1, instead of the inner layer During the treatment, increasing the roughness of the non-roughened surface 1b of the copper foil body 1 can effectively improve the adhesion of the inner layer. It is particularly important that the layers constituting the anti-corrosion layer 10 adopt a layer structure without being mixed. It has been found that the adhesion of the inner layer can be well maintained with less adhesion of chromium and zinc, and the transmission loss can be reduced more effectively. .

This high-level surface-treated copper foil, which takes into account the reduction of inner layer adhesion and transmission loss, is even more effective when using a process without inner layer treatment than before. Recently, for example, in a part of the batch build-up process and the through-pad via process, for the purpose of simplifying the process and reducing the cost, the following situation has increased, that is, the entire surface grinding and micro-etching before the resist formation is not performed to make the circuit Board, internal layer processing, omission of half-etching, partial implementation of electroless plating, etc. Even in this case, the problem of poor adhesion of the inner layer due to no inner layer treatment can be solved, and the problem of increased transmission loss due to chromium and zinc on the non-roughened surface of the surface-treated copper foil.

In addition, compared with the previous method in which the inner layer treatment is performed after the circuit pattern is made, there are also the following advantages: by using the pre-installed zinc hydroxide layer 13 and zinc oxide when manufacturing the surface-treated copper foil The method of layer 12, metal zinc layer 11 and anti-rust layer 10 can be completed with fewer manufacturing processes when manufacturing printed circuit boards, which is excellent in reducing costs and improving productivity.

The surface-treated copper foil of this embodiment takes into account the adhesion, reliability, and transmission loss reduction of the non-roughened surface 1b at a high level. Therefore, it is suitable for the production of copper-clad laminates and printed wiring boards for high-frequency transmission. Especially the surface treatment copper foil used in multilayer printed circuit boards. That is, the copper clad laminated board of this embodiment is equipped with the surface-treated copper foil of this embodiment, and the resin-made base material laminated|stacked on the roughened surface 1a side of the surface-treated copper foil of this embodiment. In addition, the printed wiring board of this embodiment is equipped with the copper clad laminated board of this embodiment.

In the surface-treated copper foil of this embodiment, electrolytic copper foil can be used as the copper foil body 1. In addition, the average height of the roughened particles on the roughened surface 1a of the copper foil body 1 can be set within a range of 0.2 µm or more and 0.8 µm or less. Moreover, the ten-point average roughness Rzjis of the non-roughened surface 1b of the copper foil main body 1 can be set to 1.5 µm or less.

The time before the roughening treatment of the copper foil used as the main body 1 of the copper foil is preferably the ten-point average roughness Rzjis measured by a stylus type roughness meter specified in JIS B0601 (2001) on both main surfaces. It is 1.5 µm or less. If the ten-point average roughness Rzjis is large, the transmission loss may increase.

When manufacturing the surface-treated copper foil of this embodiment, first, the main surface of one of the copper foils is roughened. As a representative example of the roughening treatment, copper roughening plating can be cited. In copper roughening plating, a copper sulfate plating solution is used. The sulfuric acid concentration of the copper sulfate plating solution is preferably 50 g/L to 250 g/L, more preferably 70 g/L to 200 g/L. If the sulfuric acid concentration of the copper sulfate plating solution is less than 50 g/L, the electrical conductivity may become low, and the electrodeposition properties of the roughened particles may deteriorate. If the sulfuric acid concentration of the copper sulfate plating solution is higher than 250 g/L, there is concern about the corrosion of equipment that promotes copper roughening plating.

The copper concentration of the copper sulfate plating solution is preferably 6 g/L to 100 g/L, more preferably 10 g/L to 50 g/L. If the copper concentration of the copper sulfate plating solution is less than 6 g/L, there is a concern that the electrodeposition properties of roughened particles will deteriorate. If the copper concentration of the copper sulfate plating solution is higher than 100 g/L, a larger current is required for plating into particles, which is also impractical in terms of equipment.

In the copper sulfate plating solution, organic additives or inorganic additives may also be added. If polymer polysaccharides are added as an organic additive, the diffusion limiting current density will be reduced, and roughened particles will easily be produced even under lower current density conditions. In addition, if salts and noble metal ions, which are more difficult to water soluble than copper sulfate, are added as inorganic additives, the number of roughened copper particles can be increased.

The current density in copper roughening plating is preferably 5 A/dm ² to 120 A/dm ² , more preferably 30 A/dm ² to 100 A/dm ² . If the current density is less than 5 A/dm ² , processing takes time, and therefore there is a concern that productivity will decrease. If the current density is higher than 120 A/dm ² , there is a concern that the electrodeposition properties of the roughened particles will deteriorate.

After the roughening treatment is performed, a coating plating treatment that covers the roughened particles and improves the adhesion between the roughened particles and the copper foil may be performed. In this case, the above-mentioned copper sulfate plating solution can also be used. It is also possible to repeat the double-layer treatment several times to improve the uniform electrodeposition of the roughened particles.

In addition, the roughening treatment may be performed by a method other than copper roughening plating. Examples include: roughening treatment based on dissimilar metal plating or alloy plating, roughening treatment based on etching treatment, and roughening treatment that oxidizes the surface of copper foil by oxidizing or adjusting the atmosphere. , Roughening treatment for roughening the surface by reducing and oxidizing the surface again, and roughening treatment based on a combination of these treatments, etc.

Then, an anti-rust layer 10 is provided on the non-roughened surface 1b of the copper foil. First, the metal zinc layer 11 is provided on the non-roughened surface 1b of the copper foil body 1. The formation of the metallic zinc layer 11 is preferably performed by electrolytic zinc. For the zinc plating solution, for example, an alkaline zinc plating solution is used. The zinc concentration of the alkaline zinc plating solution is preferably 2 g/L to 10 g/L. If the zinc concentration of the alkaline zinc plating solution is less than 2 g/L, there is a concern that the current efficiency of zinc will decrease and productivity will decrease. If the zinc concentration of the alkaline zinc plating solution is higher than 10 g/L, precipitation is likely to be formed in the alkaline zinc plating solution, and there is a concern that the stability of the alkaline zinc plating solution will decrease.

The sodium hydroxide (NaOH) concentration of the alkaline zinc plating solution is preferably 25 g/L to 45 g/L. If the sodium hydroxide concentration of the alkaline zinc plating solution is less than 25 g/L, there is a concern that the conductivity of the alkaline zinc plating solution will decrease and productivity will decrease. If the sodium hydroxide concentration of the alkaline zinc plating solution is higher than 40 g/L, it is easy to re-dissolve the plated zinc, and it is difficult to obtain a normal and uniform zinc plating film. The current density during zinc electroplating is preferably 0.1 A/dm ² to 1 A/dm ² , and the treatment time is preferably 2 to 5 seconds.

Then, a zinc oxide layer 12 is provided on the metal zinc layer 11. As an example of a method of forming the zinc oxide layer 12, anodizing treatment can be cited. By performing anodizing treatment under appropriate conditions, the zinc on the outermost layer of the zinc metal layer is oxidized to form a dense zinc oxide layer 12. As the anodizing treatment liquid, for example, a mixed solution of sodium hydroxide and sodium carbonate (Na ₂ CO ₃ ) can be used. The sodium hydroxide concentration of the mixed solution is preferably 2 g/L to 10 g/L. If the sodium hydroxide concentration of the mixed solution is less than 2 g/L, the zinc oxide is likely to become rough and disorderly. If the sodium hydroxide concentration of the mixed solution is higher than 10 g/L, there is a concern that the yield of zinc oxide will decrease. The sodium carbonate concentration of the mixed solution is preferably in the range of 30 g/L to 70 g/L. It is also related to the concentration of sodium hydroxide, but if it deviates from this concentration range, zinc oxide tends to become rough and disordered. Oxalic acid and ammonium borate are also used in anodizing treatment liquid.

The current density in the anodizing treatment is preferably 1 A/dm ² to 10 A/dm ² , and the treatment time is preferably 2 to 20 seconds. If the current density and the treatment time are too small, the zinc oxide layer 12 may be insufficiently formed, but if the current density and the time of the anodizing treatment are too large, the metal zinc layer 11 may be almost completely oxidized.

As an example of other methods of forming the zinc oxide layer 12, high-temperature oxidation treatment can be cited. Specifically, it is a method of oxidizing the metallic zinc layer 11 in dry air at about 80°C to 130°C for about 2 to 5 seconds. If the temperature and time of the high-temperature oxidation treatment are too small, the zinc oxide layer 12 may be insufficiently formed, but if the temperature and time of the high-temperature oxidation treatment are too large, the metal zinc layer 11 may be almost completely oxidized. The conditions of high temperature oxidation treatment need to be adjusted appropriately according to the amount of metal zinc deposited.

Then, a zinc hydroxide layer 13 is provided on the zinc oxide layer 12. As an example of a method of forming the zinc hydroxide layer 13, high-temperature steam treatment can be cited. By exposing the zinc oxide layer 12 to high-temperature water vapor, a zinc hydroxide layer 13 is formed on the outermost layer of the zinc oxide layer 12. The temperature of the high-temperature steam treatment is preferably 70°C to 100°C, and the humidity is preferably above 80%RH. The treatment time of the high-temperature steam treatment is preferably 1 to 4 seconds.

As an example of another method of forming the zinc hydroxide layer 13, a copper foil on which the zinc oxide layer 12 is formed is used as an electrode, and a cathodic polarization hydrogen generation process is performed in a neutral aqueous solution. For example, in a neutral salt solution of potassium sulfate (K ₂ SO ₄ ) and sodium sulfate (Na ₂ SO ₄ ), cathodic polarization is performed within a current density of 0.1 A/dm ² to 1 A/dm ² . The zinc hydroxide layer 13 is formed on the outermost layer by generating hydrogen on the surface of the copper foil (electrode) on which the zinc oxide layer 12 is formed. The concentration of the neutral salt in the neutral salt aqueous solution is preferably in the range of about 0.5 mol/L to 2 mol/L. The treatment time of the hydrogen generation treatment is preferably in the range of about 1 to 5 seconds.

Then, a chromate layer 14 is provided on the zinc hydroxide layer 13. The chromate treatment for forming the chromate layer 14 is roughly divided into two types: acid chromate treatment and alkaline chromate treatment. By performing any one or both of these two treatments, a chromate layer 14 made of a chromium compound is formed on the zinc hydroxide layer 13.

The so-called acidic chromate treatment is the treatment of immersing the copper foil in an acidic chromic anhydride (VI) aqueous solution, or the treatment of using the copper foil as an electrode for cathodic polarization in an acidic chromic anhydride (VI) aqueous solution. The chromium (VI) concentration of the acidic chromic anhydride (VI) aqueous solution is preferably 1 g/L to 8 g/L. If the chromium (VI) concentration is less than 1 g/L, it is not easy to obtain a sufficient amount of chromium adhesion. If it is higher than 8 g/L, the risk of operation and the cost of waste liquid treatment increase, which is not good.

The pH value of the acidic chromic anhydride (VI) aqueous solution is preferably in the range of 2 to 5. If the pH of the acidic chromic anhydride (VI) aqueous solution is lower than 2, the material in the lower layer may be excessively eluted, which is not good. If the pH value of the acidic chromic anhydride (VI) aqueous solution is higher than 5, it is difficult to obtain sufficient chromium adhesion. For pH adjustment, sulfuric acid can be used.

The current density during cathodic polarization is preferably 2 A/dm ² to 10 A/dm ² . The immersion time or the cathodic polarization treatment time also depends on the current density, but it is preferably 2 to 8 seconds. When the cathodic polarization treatment time or current density is too large, the material in the lower layer may dissolve excessively, which is not good. When the cathodic polarization treatment time or current density is too small, it is difficult to obtain sufficient chromium adhesion. The liquid temperature of the acidic chromic anhydride (VI) aqueous solution is preferably 25°C to 40°C.

The so-called alkaline chromate treatment is a treatment in which copper foil is used as an electrode for cathode polarization in an alkaline chromic anhydride (VI) aqueous solution. The chromium (VI) concentration of the alkaline chromic anhydride (VI) aqueous solution is preferably 1 g/L to 8 g/L. If the chromium (VI) concentration is less than 1 g/L, it is not easy to obtain a sufficient amount of chromium adhesion. If it is higher than 8 g/L, the risk of operation and the cost of waste liquid treatment increase, which is not good.

The pH value of the alkaline chromic anhydride (VI) aqueous solution is preferably in the range of 9-14. If the pH value of the alkaline chromic anhydride (VI) aqueous solution is lower than 9, it is difficult to obtain sufficient chromium adhesion. If the pH value of the alkaline chromic anhydride (VI) aqueous solution is higher than 14, the corrosiveness of the equipment for alkaline chromate treatment becomes higher, which is not realistic. For pH adjustment, simple alkaline salts such as sodium hydroxide and potassium hydroxide can be used.

In addition, zinc can also be added to the alkaline chromic anhydride (VI) aqueous solution. If zinc is added, the excessive elution of zinc in the lower layer can also be effectively suppressed. The zinc can also be added in the form of zinc oxide. The zinc concentration of the alkaline chromic anhydride (VI) aqueous solution is preferably in the range of 2 g/L to 10 g/L.

The non-roughened surface 1b of the copper foil on which the anti-rust layer 10 is formed by the above-mentioned series of anti-rust layer forming treatments may be further subjected to organic treatment such as a silane coupling agent. In addition, a rust preventive layer may be formed on the roughened surface 1a before, after, or at the same time as the rust preventive layer forming treatment on the non-roughened surface 1b. The anti-rust layer formed on the roughened surface 1a may be composed of nickel, zinc, chromium, etc., or may have the same structure as the anti-rust layer 10 of the non-roughened surface 1b. In addition, after the rust prevention layer is formed on the roughened surface 1a, an organic treatment such as a silane coupling agent may be further performed.

The copper clad laminated board of this embodiment is formed using the surface-treated copper foil of this embodiment mentioned above. Such a copper-clad laminated board of this embodiment can be formed by a known method. For example, a copper clad laminated board can be manufactured by laminating the roughened surface 1a (adhesive surface) of the surface-treated copper foil of this embodiment, and bonding a resin base material.

Here, as the resin used for the resin base material, polymer resins of various components can be used. For rigid circuit boards or printed circuit boards for semiconductor packages (PKG), phenol resin and epoxy resin can be mainly used. For flexible substrates, polyimide and polyimide can be mainly used. In precision patterned (high-density) circuit boards or high-frequency substrates, heat-resistant resins with high glass transition point (Tg) can be used as materials with good dimensional stability, materials with less warpage, and materials with less heat shrinkage.

Examples of heat-resistant resins include: liquid crystal polymer, polyether ether ketone, polyphenylene sulfide, polyphenylene ether, polyphenylene oxide, polyether imide, polyether sulfide, polyethylene naphthalate Thermoplastic resins such as diesters, polyethylene terephthalate, and thermoplastic polyimides, or polymer alloys composed of these, and further examples include polyimides, heat-resistant epoxy resins, and bismaleimides Cyanate resins such as imitriazine, thermosetting resins such as thermosetting modified polyphenylene ether, etc. In particular, the resin used for the resin base material of the copper-clad laminate of the present embodiment is preferably a polyphenylene ether-based resin. Polyphenylene ether resins have low dielectric loss tangent and relative dielectric constant, excellent thermal and chemical stability, and excellent adhesion to dissimilar materials. Therefore, polyphenylene ether-based resins are suitable for the use of printed wiring boards as resin substrates.

The printed wiring board of this embodiment is preferably formed using the above-mentioned copper clad laminate. Such a printed wiring board of this embodiment can be formed by a known method.

In addition, it is possible to form a desired circuit pattern by chemically etching a part of the surface-treated copper foil of the above-mentioned copper-clad laminate by a normal method to produce a printed wiring board. In addition, electronic circuit parts can of course be mounted on the circuit pattern. As electronic circuit components, those who usually mount electronic printed wiring boards can be used. In addition to individual semiconductor elements, for example, chip resistors, chip capacitors, semiconductor packages (PKG), and the like can be cited. [Example]

Examples and comparative examples are shown below to further specifically describe the present invention. For the copper foil as the main body of the copper foil, double-sided glossy electrolytic copper foil with Rzjis of 1.0 µm on the M side and 0.8 µm on the Rzjis of the S side is used. The M surface of the copper foil is subjected to copper roughening plating for roughening treatment, and further coating plating treatment is carried out to produce roughening particles with an average height of 0.2 µm or more and 0.8 µm or less Chemical treatment of copper foil. The average height of the roughened particles is calculated from the scanning electron microscope image (SEM image) of the cross section of the roughened copper foil according to the method described in Patent Document 6.

The conditions of copper roughening plating are as follows. Copper concentration of copper sulfate plating solution: 35 g/L Sulfuric acid concentration of copper sulfate plating solution: 140 g/L Temperature of copper sulfate plating solution: 27℃ Current density: 55 A/dm ² Treatment time: 4 seconds

The conditions of the plating treatment are as follows. Copper concentration of copper sulfate plating solution: 120 g/L Sulfuric acid concentration of copper sulfate plating solution: 90 g/L Current density: 10 A/dm ² Treatment time: 6 seconds

Using the roughened copper foil manufactured in this manner, the surface-treated copper foils of Examples 1 to 5 and Comparative Examples 1 to 4 were manufactured. The manufacturing method of each surface-treated copper foil is recorded below. (Example 1)

Perform the following treatments (1), (2), (3) and (4) on the S surface (non-roughened surface) of the roughened copper foil in the following order to form an anti-rust layer to obtain surface-treated copper Foil.

(1) Apply zinc electroplating to the S surface of the roughened copper foil under the conditions shown below. Zinc concentration of alkaline zinc plating solution: 3 g/L Sodium hydroxide concentration of alkaline zinc plating solution: 30 g/L Temperature of alkaline zinc plating solution: 25℃ Current density: 0.6 A/dm ² treatment Time: 5 seconds

(2) Under the conditions shown below, anodize the S surface of the roughened copper foil. The concentration of sodium hydroxide in the anodic oxidation treatment solution: 8 g/L The concentration of sodium carbonate in the anodic oxidation treatment solution: 42 g/L the temperature of the anodic oxidation treatment solution: 34℃ Current density: 5 A/dm ² treatment time: 3 seconds

(3) Under the conditions shown below, perform high temperature steam treatment on the S surface of the roughened copper foil. Temperature: 85°C Humidity: 90%RH Processing time: 3 seconds

(4) Under the conditions shown below, perform acid chromate treatment on the S surface of the roughened copper foil. Chromium (VI) concentration of acidic chromic anhydride (VI) aqueous solution: 5 g/L pH of acidic chromic anhydride (VI) aqueous solution: 3.2 Temperature of acidic chromic anhydride (VI) aqueous solution: 40℃ Current density: 5 A /dm ² processing time: 4 seconds (Example 2)

Except that the treatment shown in (4a) below was performed instead of the treatment shown in (4) above, an anticorrosive layer was formed on the S surface of the roughened copper foil in the same manner as in Example 1 to obtain a surface-treated copper foil.

(4a) Alkaline chromate treatment is performed on the S surface of the roughened copper foil under the conditions shown below. Chromium (VI) concentration of alkaline chromic anhydride (VI) aqueous solution: 5 g/L pH value of alkaline chromic anhydride (VI) aqueous solution: 13.5 Zinc concentration of alkaline chromic anhydride (VI) aqueous solution: 3 g/L L Temperature of alkaline chromic anhydride (VI) aqueous solution: 30℃ Current density: 4 A/dm ² Treatment time: 5 seconds (Example 3)

Except that the treatment shown in (4a) above was further performed after the treatment shown in (4) above, an anti-rust layer was formed on the S surface of the roughened copper foil in the same manner as in Example 1 to obtain a surface-treated copper foil . (Example 4)

Except that the treatment shown in (2a) below was performed instead of the treatment shown in (2) above, a rust preventive layer was formed on the S surface of the roughened copper foil in the same manner as in Example 3 to obtain a surface-treated copper foil.

(2a) Under the conditions shown below, perform high temperature oxidation treatment on the S surface of the roughened copper foil. Temperature: 110℃ Processing time: 5 seconds (Example 5)

Except that the treatment shown in (3a) below was performed instead of the treatment shown in (3) above, in the same manner as in Example 4, an antirust layer was formed on the S surface of the roughened copper foil to obtain a surface-treated copper foil.

(3a) Hydrogen generation treatment is performed on the S surface of the roughened copper foil under the conditions shown below. Sodium sulfate concentration of neutral salt solution: 1 mol/L Current density: 0.4 A/dm ² Treatment time: 5 seconds

As a representative example of the usual anti-rust layer formed on the non-roughened surface of copper foil, Comparative Example 1 to Comparative Example 3 are shown. (Comparative example 1)

Except that the treatments shown in (2) and (3) above are not carried out, and only the treatments shown in (1) and (4) above are carried out, it is formed on the S surface of the roughened copper foil in the same manner as in Example 1. Anti-rust layer to obtain surface-treated copper foil. (Comparative example 2)

Except that the treatments shown in (2) and (3) above are not carried out, and only the treatments shown in (1) and (4a) above are carried out, it is formed on the S surface of the roughened copper foil in the same manner as in Example 2. Anti-rust layer to obtain surface-treated copper foil. (Comparative example 3)

Except that the treatments shown in (2) and (3) above are not carried out, and only the treatments shown in (1), (4), and (4a) above are carried out, the roughening treatment of copper is carried out in the same manner as in Example 3. An anti-rust layer is formed on the S surface of the foil to obtain a surface-treated copper foil. (Comparative Example 4)

The S surface of the surface-treated copper foil of Comparative Example 3 was subjected to micro-etching treatment as an inner layer treatment. As the micro etching solution, Etch Bond CZ-8000 manufactured by MEC Co., Ltd. was used.

The surface-treated copper foils of Examples 1 to 5 and Comparative Examples 1 to 4 manufactured in the above manner were evaluated. The evaluation items are the structure of the anti-rust layer, the adhesion of the inner layer and the transmission characteristics. Regarding the inner layer adhesiveness, three inner layer adhesive properties of normal state adhesiveness, heat-resistant adhesiveness, and hydrochloric acid-resistant adhesiveness were evaluated. The evaluation method is explained below. (Evaluation method of structure of anti-rust layer)

For the S surface of the surface-treated copper foil, X-ray photoelectron spectroscopy (XPS) and hard X-ray photoelectron spectroscopy (HAXPES) are used for analysis. The XPS measurement and the HAXPES measurement were performed using an X-ray photoelectron spectroscopy analyzer PHI Quants manufactured by ULVAC PHI. With regard to incident X-rays, the monochromatic Al-Kα line (hν=1486.6 eV) was used in the XPS measurement, and the monochromatic Cr-Kα line (hν=5414.9 eV) was used in the HAXPES measurement. Both the XPS measurement and the HAXPES measurement were performed at a sweep angle of 45°.

The analysis software Multipak was used to perform background subtraction and peak separation on the Zn2p _3/2 spectrum and O1s spectrum obtained in the XPS and HAXPES determinations. The Shirley method is used for background subtraction, and the pseudo-Voigt (pseudo-Voigt) function is used for peak separation. The peak-top binding energy is allowed to be ±0.2 eV as the error range relative to the value recorded in this specification. For example, the peak of Zn(0) is 1021.8 eV, so the value in the range of 1021.6 eV to 1022.0 eV is actually used for peak separation.

According to the sequence (A) to (C) shown below, the presence and sequence of the three layers of the metal zinc layer, the zinc oxide layer and the zinc hydroxide layer were evaluated.

(A) Separate the Zn2p _3/2 spectra obtained in XPS and HAXPES respectively with the peak of Zn(0) (1021.8 eV) and Zn(II) (1022.5 eV), and calculate each peak Area rate. The unit of area ratio is %. Peak separation with only two peaks means that the area ratio of the two peaks add up to 100%. The measurement results of the copper foil of Example 1 are shown as examples in Fig. 2(a) and Fig. 2(b).

At this time, when the condition that "the area ratio of the Zn(0) peak in the HAXPES measurement is increased by 5 percentage points or more compared to the XPS measurement" (hereinafter referred to as condition A) is satisfied, it can be evaluated as being from the surface side There is a layer structure of Zn(II)/metal Zn.

(B) The O1s spectra obtained in XPS measurement and HAXPES measurement were separated by only the peak of oxide (530.9 eV) and the peak of hydroxide (532.4 eV), and the area ratio of each peak was calculated. The measurement results of Example 1 are shown as examples in Fig. 2(c) and Fig. 2(d).

At this time, when the condition that "the area ratio of the oxide peak in the HAXPES measurement is increased by more than 5 percentage points compared to the XPS measurement" (hereinafter referred to as condition B), it can be evaluated that hydrogen exists from the surface side Oxide/oxide layer structure.

(C) By satisfying both of the above conditions A and B, it can be evaluated that a three-layer structure of a metal zinc layer, a zinc oxide layer, and a zinc hydroxide layer exists in order from the copper foil side.

The results are shown in Table 1. In Table 1, the items of condition A and condition B are indicated as ○ mark when the conditions are satisfied, and × mark when the conditions are not satisfied. In addition, in Comparative Example 4, since the S surface was microetched, the XPS measurement was not used to detect zinc or the like. Therefore, in Table 1, the meaning of no data is expressed as-mark.

（內層密接性之評價方法：常態密接性）In addition, in this example and the comparative example, a chromate layer is present on the outermost layer of the non-roughened surface of the copper foil. As we all know, in the chromate layer, chromium oxide and chromium hydroxide are mixed. This confirmed that compared with the XPS measurement, the increase in the area ratio of the chromium oxide peak in the HAXPES measurement was less than 5 percent. It was confirmed that chromium does not have a layer structure and that there is a chromate layer on the outermost layer. Therefore, it can be seen that the existence of the chromate layer has no effect on the evaluation of the zinc hydroxide layer, zinc oxide layer, and metal zinc layer using this method.

(Evaluation method of inner layer adhesion: normal adhesion)

As one of the evaluations of inner layer adhesion, a normal peel test was performed based on JIS C6481:1996. On the non-roughened surface of the copper foil of the embodiment and the comparative example, that is, the S surface, two low-dielectric polyphenylene ether resin films (multilayer substrate material MEGTRON7 manufactured by Panasonic Co., Ltd., thickness 60 µm) for bonding to produce a copper-clad laminate. In addition, with regard to Examples 1 to 5 and Comparative Examples 1 to 3, a copper-clad laminated board was produced without performing overall polishing and micro-etching treatment before attaching the resin film. In Comparative Example 4, a copper-clad laminated board was produced after performing a microetching process.

After etching the copper clad laminate with copper chloride, the masking tape was removed, and a circuit board with a circuit wiring width of 10 mm was produced. In a room temperature environment, using a Tensilon testing machine manufactured by Toyo Seiki Seisakusho Co., Ltd., peel off the circuit wiring part (copper foil part) of the circuit board from the resin base material in a 90-degree direction at a speed of 50 mm/min. Measure the peel strength as the normal peel strength. The results are shown in Table 1.

In Table 1, when the normal peel strength is 0.62 N/mm or more, it is judged that the normal adhesiveness is excellent, which is indicated by ○, and when the normal peel strength is less than 0.62 N/mm, it is judged that the normal adhesiveness is insufficient, and it is judged as × The mark indicates. (Evaluation method of inner layer adhesion: heat-resistant adhesion)

As one of the evaluations of the inner layer adhesion, a heat-resistant peel test was performed based on JIS C6481:1996. The circuit board is produced in the same way as in the normal peeling test. After heating in a heated atmospheric oven at 300°C for 1 hour, it is naturally air-cooled to room temperature. Thereafter, the peel test was performed in the same manner as in the case of the normal peel test, and the peel strength was measured as the heat resistant peel strength. The results are shown in Table 1.

In Table 1, when the heat-resistant peel strength is 0.55 N/mm or more, the heat-resistant adhesiveness is judged to be excellent, which is indicated by ○, and when the heat-resistant peel strength is less than 0.55 N/mm, the heat-resistant adhesiveness is judged to be insufficient, and the mark is × The mark indicates. (Evaluation method of inner layer adhesion: hydrochloric acid resistance)

As one of the evaluations of the inner layer adhesion, a hydrochloric acid peel test was performed based on JIS C6481:1996. The circuit board was fabricated in the same manner as in the normal peel test, and immersed in hydrochloric acid with a liquid temperature of 25°C and a concentration of 12% by mass for 30 minutes. Then, after careful water washing, a peel test was performed in the same manner as in the normal peel test, and the peel strength was measured as the hydrochloric acid peel strength. The results are shown in Table 1.

In Table 1, when the hydrochloric acid peel strength is 0.55 N/mm or more, it is judged to be excellent in hydrochloric acid adhesion resistance, which is indicated by ○, and when the hydrochloric acid resistance peel strength is less than 0.55 N/mm, it is judged as hydrochloric acid resistance adhesion. Insufficient, indicated by × mark. (Evaluation method of transmission characteristics)

Using the copper foil of the Examples and Comparative Examples and the low-dielectric polyphenylene ether resin film as a resin base material (Multilayer substrate material MEGTRON7 manufactured by Panasonic Corporation, thickness 60 µm), the cross section shown in Figure 3 was produced The structure is formed with a circuit board with lines to evaluate the transmission characteristics. The width of the circuit with circuit formed on the circuit board is set to 140 µm, and the circuit length is set to 310 mm.

Specifically, the resin layers 30 and 30 are arranged on both surfaces of the copper foil 22, and the copper foils 21 and 23 are respectively laminated on the resin layers 30 and 30 to produce a wiring board. The resin layers 30 and 30 are both composed of two laminated low-dielectric polyphenylene ether resin films. In addition, both the copper foils 21 and 23 are arranged with the roughened surface facing the resin layer 30 side.

For Comparative Example 4, first, the copper foil of Comparative Example 3 was used to form a circuit by copper chloride etching, and then a microetching treatment was performed, and then the outer layer copper-clad laminate was bonded.

In addition, the microstrip line exposed on the side of the non-roughened surface is also used for the evaluation of transmission characteristics, but the influence of the side of the non-roughened surface on the transmission characteristics cannot be accurately measured. Therefore, it is used as the multilayer printed circuit of the present invention. The evaluation of the copper foil for the board is not appropriate, and the evaluation of the strip circuit as in this example is appropriate.

A network analyzer N5291A manufactured by Keysight Technologies was used to transmit a high frequency signal to the circuit of the copper foil 22 formed on the circuit board, and the transmission loss was measured. The copper foils 21 and 23 are grounded. The characteristic impedance is set to 50 Ω. The smaller the absolute value of the measured value of transmission loss, the less transmission loss, which means that high-frequency signals can be transmitted well. The results are shown in Table 1.

In Table 1, when the absolute value of the measured transmission loss at 28 GHz is less than 11 dB/310 mm, it is judged that the transmission loss is small, indicated by the ○ mark, and the value is 11 dB/310 mm or more and less than 15 dB/ When 310 mm, it is judged that the transmission loss is slightly larger, which is indicated by the × mark, and when it is 15 dB/310 mm or more, it is judged that the transmission loss is large, which is indicated by the ×× mark.

It can be seen from Table 1 that the copper foils of Examples 1 to 5 are copper foils satisfying conditions A and B, and are all excellent in normal adhesion, heat-resistant adhesion, hydrochloric acid resistance, and transmission characteristics.

In contrast, the copper foils of Comparative Examples 1 to 3 are copper foils with the previous anti-rust layer on the non-roughened surface. It was confirmed that the conditions A and B were not satisfied and the normal adhesion was excellent, but the heat-resistant adhesion and resistance Hydrochloric acid has poor adhesion and transmission characteristics. The copper foil of Comparative Example 4 was subjected to a microetching treatment, and therefore, it was confirmed that the normal adhesiveness, heat-resistant adhesiveness, and hydrochloric acid-resistant adhesiveness were excellent, but the transmission characteristics were significantly poor.

1: Copper foil body 1a: roughened surface 1b: non-roughened surface 10: Anti-rust layer 11: Metal zinc layer 12: Zinc oxide layer 13: Zinc hydroxide layer 14: Chromate layer 21: Copper foil 22: Copper foil 23: copper foil 30: resin layer

Fig. 1 is a cross-sectional view showing the structure of a surface-treated copper foil according to an embodiment of the present invention. Figure 2 is a graph showing the results of XPS analysis and HAXPES analysis of the anti-corrosion layer of the copper foil of Example 1. Fig. 3 is a cross-sectional view showing the structure of a circuit board for evaluating transmission characteristics.

Domestic deposit information (please note in the order of deposit institution, date and number) no Foreign hosting information (please note in the order of hosting country, institution, date and number) no

1: Copper foil body

1a: roughened surface

1b: non-roughened surface

10: Anti-rust layer

11: Metal zinc layer

12: Zinc oxide layer

13: Zinc hydroxide layer

14: Chromate layer

Claims (6)

A surface-treated copper foil, comprising: a copper foil body, one of its two main surfaces is a roughened surface formed by a roughening treatment, and the other is a non-roughened surface; and an anti-rust layer formed on The aforementioned non-roughened surface of the aforementioned copper foil body; and The aforementioned anti-rust layer has a metal zinc layer composed of metallic zinc, a zinc oxide layer composed of zinc oxide, a zinc hydroxide layer composed of zinc hydroxide, and a chromate layer composed of a chromium compound. The layers of the rust layer are laminated in the order of the metal zinc layer, the zinc oxide layer, the zinc hydroxide layer, and the chromate layer from the copper foil main body side. The surface-treated copper foil according to claim 1, wherein the copper foil body is an electrolytic copper foil. The surface-treated copper foil according to claim 1 or 2, wherein the ten-point average roughness Rzjis of the non-roughened surface is 1.5 µm or less. The surface-treated copper foil according to any one of claims 1 to 3, wherein the average height of the roughened particles on the roughened surface is in the range of 0.2 µm or more and 0.8 µm or less. A copper-clad laminated board comprising: the surface-treated copper foil according to any one of claims 1 to 4 and a resin-made substrate laminated on the roughened surface side of the surface-treated copper foil. A printed wiring board provided with the copper-clad laminated board according to claim 5.

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