JP2007501330A - Method for producing copper foil for printed circuit board - Google Patents

Abstract

The present invention relates to a method for producing a copper foil laminated on a printed circuit board to form various circuit networks. In the method of the present invention, a rough surface layer made of a copper electrodeposit 12 is formed on the convex portion 11 or the smooth surface of the bonded surface of the copper foil. Electrolyzing the copper foil. In such a case, by further adding an inorganic polyanion having a molecular weight of 2000 or more to the plating solution in the electrolysis tank, the contact area of the adherend surface of the copper foil is relatively increased, and the copper foil and the resin substrate are in contact with each other. Adhesive strength is always maintained, electrical properties and acid resistance are improved, and copper powder fall is minimized.
[Selection] Figure 3

Description

  The present invention relates to a rough-processed copper foil that is laminated on a printed circuit board to form various circuit networks, and in particular, by increasing the surface area of the copper foil and increasing the adhesive strength between the copper foil and the resin. The present invention relates to a method for manufacturing a copper foil for a printed circuit board that improves the mechanical characteristics.

  In general, printed circuit boards are used as electronic parts used in precision control circuits such as electrical equipment and electronic communication equipment, and wiring is made using copper foil on one or both sides of an insulating substrate such as synthetic resin. After that, an IC or an electronic component is arranged on the substrate, and the wiring is electrically wired between them and coated with an insulator.

  When a printed circuit board is to be composed of multiple layers, a copper foil is laminated on an insulating substrate under high temperature and high pressure, a circuit pattern is screen printed, and this is etched into a commercial etching solution to form a circuit network. After that, a rough surface layer is formed on the surface of the copper foil, and then an element such as a semiconductor device is mounted.

  At this time, the copper foil for the printed circuit board is formed by forming a rough surface layer made of a large number of protruding copper electrodeposits on the surface to be bonded, thereby maximizing the surface area. Adhesive performance between them, that is, sufficient adhesive strength can be maintained even in processes such as high-temperature heating, wet processing, welding, and chemical processing.

  Therefore, as shown in FIG. 1 and FIG. 2, as a means for increasing the adhesive strength of the copper foil, when a ridge-shaped convex portion 11 is formed on the copper foil, the copper electrodeposit 12 is electrically connected to the convex portion 11. When the copper foil is not provided with the mountain-shaped convex portions 11, the copper electrodeposit 12 is electrodeposited on the smooth surface of the copper foil to form a rough surface layer.

  However, as a result of forming the rough surface layer made of the copper electrodeposit 12 on the convex portion 11 in the copper electrolysis tank, as shown in FIG. 2, the copper electrodeposited material covers a wide range along the peaks and valleys of the convex portion 11 as shown in FIG. Since 12 is electrodeposited in a mixed state, the adhesive surface with the resin substrate is reduced by the copper foil, the adhesive performance with the insulating substrate is deteriorated, and the copper foil may be peeled off from the resin substrate. was there.

  On the other hand, as a method of forming the copper electrodeposit 12 on the convex portion 11 of the copper foil, Japanese Patent Laid-Open No. 54-38053 and Japanese Patent Laid-Open No. 53-39327 disclose arsenic, antimony, There has been proposed a technique that includes elements of Group 6B of the periodic table such as bismuth and selenium and that is electrolyzed before and after the limiting current density.

  However, when arsenic is contained in the electrolysis tank, since a certain amount of arsenic is contained in the copper electrodeposit during the electrolysis process, copper foil regeneration and other treatment processes, and an arsenic-dissolving etching solution In the process of disposal, arsenic can cause serious environmental and health problems.

  On the other hand, as a method of forming the copper electrodeposit 12 on the convex portion 11 of the copper foil, a method using a benzoquinoline-added tank described in Japanese Patent Application Laid-Open No. 56-411196, and Japanese Patent Application Laid-Open No. Sho 62- No. 56777, a method using a tank to which molybdenum or vanadium or both are added; Japanese Patent Application Laid-Open No. 63-17597 and Japanese Patent Application Laid-Open No. 58-164797 propose a pulse plating method, or include vanadium, zinc, iron, nickel, cobalt, chromium, or the like.

  However, since these methods do not contain toxic elements such as arsenic, there is an advantage that they do not adversely affect the environment and health, but the peaks and valleys of the protrusions 11 formed on the copper foil. Since the electrodeposits 12 are mixed and electrodeposited, the adhesive strength with the insulating substrate is lowered, and the copper electrodeposits 12 may be peeled off.

  Accordingly, the present invention takes into account the conventional problems in the related art described above, and an object of the present invention is to increase the surface area of the copper foil and improve the adhesive strength between the insulating substrate and the copper foil, thereby improving the printed circuit. An object of the present invention is to provide a method for producing a copper foil for a printed circuit board that improves the electrical characteristics of the board.

  In order to achieve the above object, the present invention provides a method for producing a copper foil for a printed circuit board, in which a rough surface layer made of a copper electrodeposit is formed on the convex or smooth surface of the copper foil. In the decomposition tank, the copper foil used as the cathode was electrolyzed at the limiting current density, and the inorganic polyanion containing tungsten and having a molecular weight of 2000 or more in the plating solution of the electrolytic tank, tungsten in the plating solution of the electrolytic tank Copper for printed circuit boards, characterized in that an inorganic polyanion having a molecular weight of 2000 or more containing phosphorus and phosphorus, or an inorganic polyanion having a molecular weight of 2000 or more containing tungsten and silicon is further added to a plating solution in an electrolysis tank. A method of manufacturing a foil is provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 3 is an electron micrograph showing a state in which a copper electrodeposit is electrodeposited on the convex portion of the copper foil in the present invention. In a method for producing a copper foil for a printed circuit board, when a copper foil serving as a cathode is electrolyzed at a limiting current density in an acidic electrolysis tank, a copper electrodeposit 12 is formed on a convex portion 11 or a smooth surface of the copper foil. A rough surface layer is formed. At this time, an inorganic polyanion having a molecular weight of 2000 or more containing tungsten is further added to the plating solution in the electrolysis tank. Alternatively, an inorganic polyanion having a molecular weight of 2000 or more containing tungsten and phosphorus is further added to the plating solution in the electrolysis tank. Alternatively, an inorganic polyanion having a molecular weight of 2000 or more containing tungsten and silicon is further added to the plating solution in the electrolysis tank.

  First, Table 1 shows the composition and plating conditions of the plating solution contained in the acidic electrolysis tank according to the present invention. Further, instead of arsenic added to the plating solution, an inorganic polyanion having a molecular weight of 2000 or more that does not adversely affect the environment is added.

  In addition, as a result of further adding an inorganic polyanion to the acidic copper electrolysis tank to form a rough surface layer, only the development of the dendrite structure is caused in the process of electrodepositing the copper electrodeposit 12 on the convex portion 11 of the copper foil. Rather, nucleation is suppressed. As a result, as shown in FIG. 3, the copper electrodeposit 12 is formed in a spherical shape.

  In addition, as a supply source of the inorganic polyanion, paratungstic acid, metatungstic acid, 12-phosphotungstic acid, 12-molybdenum tungstic acid, or a sodium salt or ammonium salt thereof can be used. At this time, the inorganic polyanion is added at a concentration of 0.001 to 5 g / l in the plating solution of the copper electrolysis tank. Or it is good also as 0.01-2 g / l.

  The method according to the present invention can be applied not only to a copper foil having convex portions 11 formed on the outer surface, but also to an electrolytic copper foil or rolled copper having no convex portions 11 formed on the outer surface of the copper foil. It can be applied to foil and the like.

  Hereinafter, embodiments and comparative examples according to the present invention will be described in detail with reference to the accompanying drawings.

Electrolytic copper foil with a thickness of 35 μm using an aqueous solution of 30 ° C. containing copper sulfate pentahydrate 100 g / l, sulfuric acid 200 g / l and sodium metatungstate 0.001 to 5 g / l in an electrolysis tank The surface to be bonded was plated at a current density of 20 A / dm ² for 6 seconds. Thereafter, plating was performed at a current density of 20 A / dm ² for 10 seconds using an electrolytic solution at 45 ° C. containing 50 g / l of copper ions and 100 g / l of sulfuric acid.

  Next, the copper foil obtained in Example 1 was heated and pressed on an epoxy resin (not shown) to produce a copper foil laminate, and then the adhesive strength between the copper foil and the resin was measured using UTM. Regarding the falling of the copper powder, the resin surface after etching was observed using an optical microscope. The results are shown in Table 2.

  At this time, the adhesive strength between the copper foil and the resin was measured 10 times. As a result, it was found that the average value was very excellent at about 2.25 kg / cm. In addition, it was found that there was no drop of copper powder and the electrodeposition efficiency of the copper electrodeposit was very high.

  That is, as shown in FIG. 3, since the copper electrodeposit 12 having a uniform size is formed at the peak portion of the convex portion 11 of the copper foil, the adhesion area with the epoxy resin is greatly increased compared to FIG. Thus, it can be estimated that the adhesion performance is improved.

  In addition, when sodium metatungstate was added to the acidic copper electrolysis tank at a concentration of less than 0.001 g / l, the adhesive strength did not increase and the copper powder dropped after etching. It was also found that the economic burden would be excessive under conditions where sodium metatungstate was added at a concentration of 5.0 g / l or more.

Electrolytic copper having a thickness of 35 μm using an aqueous solution of 30 ° C. containing copper sulfate pentahydrate 100 g / l, sulfuric acid 200 g / l, and 12-silicotungstic acid 0.001 to 5 g / l in an electrolysis tank and 6 seconds plated at a current density of 20A / dm ² surface to be adhered of the foil. Thereafter, plating was performed at a current density of 20 A / dm ² for 10 seconds using an electrolytic solution at 45 ° C. containing 50 g / l of copper ions and 100 g / l of sulfuric acid.

  Next, after the copper foil obtained in Example 2 was heated and pressed on an epoxy resin to produce a copper foil laminate, the adhesive strength between the copper foil and the resin was measured using UTM, and the copper powder dropped. About the resin surface after etching of copper foil was observed using the optical microscope. The results are shown in Table 2.

  At this time, the adhesive strength between the copper foil and the resin was measured 10 times. As a result, it was found that the average value was very excellent at about 2.20 kg / cm. It was also found that there was no copper powder falling and the electrodeposition efficiency of the copper electrodeposit was high.

  That is, since the copper electrodeposit 12 having a slightly smaller size than that of Example 1 is formed at the peak portion of the convex portion 11 of the copper foil, the adhesion area with the epoxy resin is greatly increased as compared with FIG. Therefore, it can be estimated that the adhesion performance with the resin substrate is improved.

  In addition, when 12-silicotungstic acid was added to the acidic copper electrolysis tank at a concentration of less than 0.001 g / l, the adhesive strength did not increase and the copper powder dropped after etching. It was also found that the economic burden would be excessive under conditions where 12-silicotungstic acid was added at a concentration of 5.0 g / l or more.

(Comparative Example 1)
As an example that does not contain additives, an adhesive surface of an electrolytic copper foil having a thickness of 35 μm using an aqueous solution containing 30 g of copper sulfate pentahydrate and 30 g of sulfuric acid containing 100 g / l of sulfuric acid in an electrolysis tank. Was plated for 6 seconds at a current density of 20 A / dm ² . Thereafter, plating was performed at a current density of 20 A / dm ² for 10 seconds using an electrolytic solution at 45 ° C. containing 50 g / l of copper ions and 100 g / l of sulfuric acid.

  Next, after the copper foil obtained in Comparative Example 1 was heated and pressed on an epoxy resin to produce a copper foil laminate, the adhesive strength between the copper foil and the resin was measured using UTM, and the copper powder dropped. The surface of the resin after etching was observed using an optical microscope. The results are shown in Table 2.

  At this time, as a result of measuring the adhesive strength between the copper foil and the resin 10 times, it was found that the average value was about 1.93 kg / cm, which was significantly lower than those of Examples 1 and 2. In addition, it was found that the copper electrodeposits on the convex portions were not formed in a spherical shape, but were formed in a needle shape, which caused a drop of copper powder, resulting in a decrease in electrodeposition efficiency.

(Comparative Example 2)
Using an aqueous solution containing 30 g of copper sulfate pentahydrate, 100 g / l of sulfuric acid, 200 g / l of sulfuric acid, and 3 g / l of arsenic acid in the electrolysis tank, the current density was applied to the adherend surface of the 35 μm thick electrolytic copper foil. Plating was performed at 20 A / dm ² for 6 seconds. Thereafter, plating was performed at a current density of 20 A / dm ² for 10 seconds using an electrolytic solution at 45 ° C. containing 50 g / l of copper ions and 100 g / l of sulfuric acid.

  Next, after the copper foil obtained in Comparative Example 2 was heated and pressed on an epoxy resin to produce a copper foil laminate, the adhesive strength between the copper foil and the resin was measured using UTM, and the copper powder dropped. The surface of the resin after etching was observed using an optical microscope. The results are shown in Table 2.

  At this time, the adhesive strength between the copper foil and the resin was measured 10 times. As a result, the average value was about 2.21 kg / cm, which was almost the same as in Examples 1 and 2. Moreover, the copper powder did not fall and the electrodeposition efficiency was good, but it was found that about 100 PPM of arsenic was contained, which had an adverse effect on the environment and health.

  From the above results, a rough surface layer made of a copper electrodeposit was formed by further adding an inorganic polyanion having a molecular weight of 2000 or more to an acidic electrolysis tank. As a result, it was found that the copper electrodeposit 12 that was electrodeposited on the adherend surface of the copper foil was formed in a spherical shape as shown in FIG. 3, and the surface area of the copper foil was relatively increased.

  As described above, the present invention provides a method for producing a copper foil for a printed circuit board. A rough surface layer made of a spherical copper electrodeposit is formed on the adherend surface of the copper foil, and the contact area of the adherend surface of the copper foil is relatively increased. As a result, not only the adhesion and heat resistance with the insulating substrate are improved, but also the adhesive strength between the copper foil and the resin substrate is always maintained, the electrical characteristics and acid resistance are improved, and the copper powder falls to a minimum. To do.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. However, without departing from the scope and spirit of the invention disclosed in the appended claims, those skilled in the art will recognize various modifications, additional examples, A substitution example can be conceived.

It is the electron micrograph which showed the convex part of copper foil regarding a prior art. It is the electron micrograph which showed the state by which the copper electrodeposit was electrodeposited on the convex part of the copper foil of FIG. It is the electron micrograph which showed the state by which the copper electrodeposit was electrodeposited on the convex part of copper foil regarding this invention.

Claims (5)

In a method for producing a copper foil for a printed circuit board;
In order to form a rough surface layer made of a copper electrodeposit on the convex or smooth surface of the copper foil, the copper foil as a cathode is electrolyzed at a limiting current density in an acidic electrolysis tank,
A method for producing a copper foil for a printed circuit board, wherein an inorganic polyanion having a molecular weight of 2000 or more containing tungsten is further added to the plating solution of the electrolysis tank. In a method for producing a copper foil for a printed circuit board;
In order to form a rough surface layer made of a copper electrodeposit on the convex or smooth surface of the copper foil, the copper foil as a cathode is electrolyzed at a limiting current density in an acidic electrolysis tank,
A method for producing a copper foil for a printed circuit board, wherein an inorganic polyanion having a molecular weight of 2000 or more containing tungsten and phosphorus is further added to the plating solution of the electrolysis tank. In a method for producing a copper foil for a printed circuit board;
In order to form a rough surface layer made of a copper electrodeposit on the convex or smooth surface of the copper foil, the copper foil as a cathode is electrolyzed at a limiting current density in an acidic electrolysis tank,
A method for producing a copper foil for a printed circuit board, wherein an inorganic polyanion containing tungsten and silicon and having a molecular weight of 2000 or more is further added to the plating solution of the electrolysis tank.   The copper foil for a printed circuit board according to claim 1, wherein the inorganic polyanion is added to the plating solution at a concentration of 0.001 to 5 g / l. Method. 5. The printed circuit board for a printed circuit board according to claim 4, wherein the inorganic polyanion is contained in an electrolytic solution to which at least one selected from the group of vanadium, zinc, iron, nickel, cobalt, and chromium is added. A method for producing copper foil.

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