JPS6210291A - Electrolytic copper foil - Google Patents

Abstract

PURPOSE:To obtain copper foil showing high tensile strength and elongation at ordinary and high temps. and having satisfactory bending resistance by carrying out electrolysis with an electrolytic soln. contg. a certain amount of an electrolytic soln. immediately after treatment with activated carbon. CONSTITUTION:Part of an electrolytic soln. fed from an electrolytic soln. feeding line 1 is treated with activated carbon by passing through a column 2 packed with activated carbon. The remaining electrolytic soln. is allowed to join the treated electrolytic soln. and introduced into an electrolytic cell 3 provided with a cathode drum 4 and insoluble anodes 5 within 20min after the treatment to carry out electrolysis. The amount of the treated electrolytic soln. is >=60vol% of the total amount. Electrolytic copper foil 6 deposited on the cathode drum 4 by the electrolysis is stripped and recovered. Thus, copper foil having superior mechanical properties, high hot elongation and satisfactory bending resistance after heating is obtd.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to electrolytic copper foil, and more specifically, when copper foil is obtained by electrolysis, 60% by volume or more of the electrolyte is treated with activated carbon.
This invention relates to an electrolytic copper foil used for copper-clad laminates, etc., which has significantly improved elongation, bending resistance, etc. by using a copper foil of less than 10 minutes.

[Problems to be solved by the invention] In recent years, in the field of electronics industry including computers, multi-layering of circuits has been actively carried out in order to increase the density and reliability of circuits. In particular, multi-layered copper-clad laminates are used.

Conventionally, electrolytic copper foil has generally been used as the copper foil for copper-clad laminates used in this printed circuit board. This electrolytic copper foil uses a rotating cathode drum, passes an electrolytic solution containing additives such as glue into an electrolytic bath, and electrodeposit copper onto the rotating cathode drum. A continuous electrolytic method is used to strip off the copper foil.

Electrolytic steel foil produced by this conventional method does not have its mechanical properties significantly improved by heat treatment at a low temperature of around 170° C., and is more likely to break when bent than rolled steel foil.

In addition, this electrolytic copper foil has a low elongation of around 3.0% or less, especially when hot (for example, in a 180°C atmosphere), and according to IPC-CF-150E, which is the ANSI standard for copper foil,
Classes 1 to 4 are established based on surname and ability. In particular, in class 4, by heat-treating the copper foil, we have varieties that have a hot elongation rate of 4.0% or more at 180°C. was considered difficult.

Furthermore, with such electrolytic copper foil, cracks may appear in the copper foil during the process of applying thermal stress during the production of copper foil laminates, especially multilayer copper foil laminates, and flexible printed wiring boards where bending resistance is important. It lacked reliability for use in the

The purpose of the present invention is to achieve the following:
The object of the present invention is to provide an electrolytic steel foil that has elongation at room temperature and hot temperature and has mechanical properties equivalent to or better than rolled copper foil.

[Means and effects for solving the problem] The present inventors have developed a so-called hot ( For example, we have conducted dozens of tests to manufacture electrolytic copper foil that has high elongation at 180°C (in an atmosphere).

Among them, when carrying out activated carbon treatment for the purpose of cleaning the electrolyte, if 60% by volume or more of the electrolyte to be subjected to electrolysis is continuously treated with activated carbon and electrolyzed immediately,
We have discovered that it is possible to create an electrolytic copper foil with very unique mechanical properties, leading to the present invention.

That is, the present invention resides in an electrolytic copper foil that has been subjected to electrolysis using an electrolytic solution containing 60% by volume or more within 20 minutes after being treated with activated carbon.

In order to obtain the electrolytic steel foil of the present invention, the electrolytic solution used for electrolysis must be
0% or more of the volume is treated with activated carbon. If the activated carbon-treated foil is not vortexed by 60% by volume, an electrolytic copper foil having a high hot elongation rate cannot be obtained. In addition, it is necessary to use this activated carbon-treated electrolyte within 20 minutes after the activated carbon treatment, and electrolytic copper foil with a similarly high hot elongation rate cannot be obtained even if it is used for more than 20 minutes. No, please note that
Activated carbon treatment has been conventionally performed for the purpose of cleaning the electrolyte, but the activated carbon-treated electrolyte is not electrolyzed within 20 minutes as in the present invention, and is left in the drum can for at least one day. It is normal to store it in

Next, the method for manufacturing electrolytic copper foil of the present invention will be explained based on FIG.

FIG. 1 is a schematic diagram showing an example of a continuous electrolysis system for manufacturing the electrolytic copper foil of the present invention, in which 1 is an electrolyte introduction line;
2 is an activated carbon packed tower, 3 is an electrolytic cell, 4 is a cathode drum, 5 is an insoluble anode, and 6 is an electrolytic copper foil, and the arrows indicate the flow of the electrolyte.

The continuous electrolysis method itself is almost the same as the conventional method, but it is characterized by passing a certain amount of electrolyte through a bed of activated carbon just before electrolysis, processing it at a superficial velocity of 30 cm/sea or less, and providing electrolysis within 20 minutes. be.

That is, a certain amount of the electrolyte introduced from the electrolyte supply line 1 is introduced into the activated carbon packed tower 2 and treated with activated carbon, and the electrolyte that has been treated with activated carbon for less than 20 minutes is mixed with the untreated electrolyte. They are combined and introduced into the electrolytic cell 3 for electrolysis. During this electrolysis, 60% of the electrolyte in the electrolytic cell 3
In the present invention, it is necessary that at least % by volume of the electrolytic solution be treated with activated carbon within 20 minutes. This electrolysis is performed using a cathode drum 4 and an insoluble anode 5,
Electrolytic copper foil 6 is deposited on cathode drum 4. The electrolyte composition, electrolysis time, current density, bath temperature, etc. during this electrolysis can be adjusted as desired. Electrolytic copper foil 6 deposited on cathode drum 4
is stripped and used for applications such as copper-clad laminates.

The electrolytic copper foil produced in this way has a different electrodeposition state than before due to both the cleaning effect of the activated carbon in the electrolyte and the effect that is thought to be caused by the redox action of the metal cations in the electrolyte. It has better mechanical properties in all respects than conventional electrolytic steel foil, and exhibits physical property values equivalent to or better than rolled copper foil. In particular, the hot elongation is dramatically increased compared to conventional electrolytic copper foil, and the bending resistance during hot soaking is also extremely good.

[Examples] The present invention will be specifically described below based on Examples and Comparative Examples.

As the LLL upper electrolyte, 1iiWI steel (Cu SOa ・5
+-120) 280~360M! , sulfuric acid 100~
Using a 150 g/J sulfuric acid acidic copper sulfate solution,
Electrolysis was carried out at 0°C and a current density of 50 to 100 A/d.

Electrolysis was carried out at a superficial velocity of 30 cr/sec, and continuous electrolysis was performed while 80% by volume of the electrolytic solution to be subjected to electrolysis was continuously treated with activated carbon. In addition, the time after activated carbon treatment until it was subjected to electrolysis was 5 minutes.

The normal state of the 35 μm electrolytic copper foil obtained in this way (23
°C), hot pickling (180 °C, after heating for 1 hour), hot soaking (180 °C, after heating for 1 hour)
°C) tensile strength, elongation, and MIT bending resistance by IPC-C
Along with the standards for classes 1 to 4 specified for F-150E,
As shown in the table, micrographs (ioo) show the metallographic structure of the electrolytic copper foil in normal state and hot soaked.

times) are shown in Figure 2 (a> and <<b>).

Comparative Example 1 Using the same electrolyte as in Example 1, continuous electrolysis was carried out under the same electrolytic conditions as in Example 1 without any activated carbon treatment.

The tensile strength, elongation, and MIT bending resistance of the 35 μm electrolytic copper foil obtained in this manner are shown in Table 1 in the normal state, hot soaking (after heating at 180°C for 1 hour), hot <180°C), and the MIT bending resistance.
Micrographs of electrolytic copper foil in normal condition and hot soaked (1000x magnification)
are shown in FIGS. 3(a) and (b).

Comparative Example 2 35 μm rolled steel foil (rolled copper foil for printed circuits, TPO
-35, manufactured by Mitsui Kinzoku Mining Co., Ltd.), the tensile strength, elongation, and MIT bending resistance in normal state, hot (180 ° C., after heating for 1 hour), and hot (180 ° C.) are shown in Table 1.
Micrographs of normal and hot rolled copper foil (1000x magnification)
are shown in FIGS. 4(a) and (b).

Table 1 As shown in Table 1, the electrolytic steel foil of Example 1 was treated as PC-CF-150E class 1 without heat treatment.
It satisfies all of the required physical properties of 4 to 4, and the bending resistance is also within a preferable range. On the other hand, the electrolytic copper foil of Comparative Example 1 does not satisfy the normal elongation of Class 2 or the hot elongation of Classes 3 and 4, and requires heat treatment, and the bending resistance is also lower than that of Example 1. shows a lower value compared to . Moreover, the rolled steel foil of Comparative Example 2 does not satisfy the normal elongation of classes 1 to 4, requires heat treatment, and exhibits a lower bending resistance than Example 1.

In addition, as shown in FIGS. 2 to 4 (a) and (b), the metal structures of the copper foils of Example 1 and Comparative Examples 1 and 2 in the normal state and after hot soaking are the same as those of the electrolytic steel foil of Example 1. , 18
After heating at 0°C for 1 hr, the copper foil of Comparative Example 2 was clearly made bulky, which was different from that of the electrolytic copper foil of Comparative Example 1 (see Fig. 2(b)).
A phenomenon similar to that of rolled copper foil occurs. At this time, as shown in Table 1, the elongation after heat treatment was as high as 19%, and the bending resistance required for flexible printed circuit boards was greatly improved.

This test was conducted on 35 μm copper foil, but 1
Almost similar results were obtained with copper foils of 8 μm and 70 μm.

Examples 2 to 4 and Comparative Examples 3 to 5 Copper sulfate (Cu SOa 5H20
)250-280 (J/), sulfuric acid 90-120o/J
Electrolysis was carried out using a sulfuric acid M copper sulfate solution at a liquid temperature of 50°C and a current rate of 50 to 150 A/drd.

Electrolysis was carried out at a superficial velocity of 30 CIn/Sec, and part or all of the electrolyte was treated with continuous activated carbon.
Continuous electrolysis was performed. In addition, the time after activated carbon treatment until it was subjected to electrolysis was 5 minutes.

The 35μmN copper-deposited foil thus obtained was heated (18
Table 2 shows the elongation (at 0°C) and the activated carbon-treated ratio of the electrolytic solution used for electrolysis.

Table 2 As shown in Table 2, the electrolytic steel foils of Examples 2 to 4 obtained by electrolysis using an electrolytic solution in which the proportion of the activated carbon-treated electrolytic solution was 60% by volume or more were hot elongated. It can be seen that the electrolytic copper foils of Comparative Examples 3 and 4 obtained by electrolyzing using an unvortexed electrolyte in which the proportion of the activated carbon-treated electrolyte was 60% by volume had a low hot elongation. . Therefore, in the present invention, it is necessary to conduct electrolysis using an electrolytic solution in which the proportion of the electrolytic solution treated with activated carbon is 60% by volume or more.

Examples 5 to 7 and Comparative Example 5 Copper sulfate (CuSO4・5H20)2 as the electrolyte
50~280 (1/J, sulfur M90~1201J/
Electrolysis was carried out using a sulfuric acid acidic copper sulfate solution of J, at a liquid temperature of 50°C and a current density of 50 to 150 A/dTIt.

Continuous electrolysis was performed at a superficial velocity of 30 cm/sec while 80% by volume of the electrolyte to be subjected to electrolysis was continuously treated with activated carbon. Further, the time after the activated carbon treatment of the electrolytic solution until it was subjected to electrolysis was set to 2.5 minutes, 10 minutes, 20 minutes, and 30 minutes, respectively.

The thus obtained 35 μm electrolytic copper foil was heated (18
Table 3 shows the elongation (at 0°C) and the time until electrolysis of the activated carbon-treated electrolyte.

Table 3 As shown in Table 3, the electrolytic copper foils of Examples 5 to 7 obtained by electrolysis using an electrolytic solution within 20 minutes after being treated with activated carbon have high hot elongation. On the other hand, it can be seen that the electrolytic copper foil of Comparative Example 5, which was obtained by electrolysis using an electrolyte solution 30 minutes after the activated carbon treatment, had low hot elongation. For this reason, in the present invention, it is necessary to perform electrolysis using an electrolytic solution within 20 minutes after the activated carbon treatment.

[Effects of the Invention] As described above, the electrolytic copper foil of the present invention obtained by electrolysis using an electrolytic solution containing 60% by volume or more within 20 minutes after being treated with activated carbon has a Since it exhibits high tensile strength and elongation, there is no fear of cracks occurring due to thermal stress during thermal processing when used in multilayer copper-clad laminates, etc., and the electrolytic copper foil of the present invention also has good bending resistance. Therefore, it can exhibit high reliability when used in flexible printed wiring boards.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a continuous electrolysis system for producing the electrolytic steel foil of the present invention, and FIG. Micrograph showing the structure (1000x)
, Figures 3 (a) and (b) are micrographs (1000x magnification) showing the metallographic structures of the normal and antecedent electrolytic copper foils of Comparative Example 1.
, and FIGS. 4(a), 8, and 4(b) are micrographs (1000x magnification) showing the metallographic structure of the electrolytic steel foil of Comparative Example 2 in normal state and hot soaked. 1: N solution introduction line, 2: activated carbon packed tower, 3: electrolytic cell, 4: cathode drum, 5: insoluble anode,
62 electrolytic steel foil.

Claims (1)

[Claims] 1. Electrolytic copper foil obtained by electrolysis using an electrolytic solution containing 60% by volume or more of electrolytic solution within 20 minutes after being treated with activated carbon.