JPH10183264A - Method for recovering copper from glass epoxy substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily recovering copper from waste printed circuit boards at a low cost. SOLUTION: The glass epoxy substrates 1 from which packaging parts are removed are immersed at >=60 to <130 deg.C in an aq. sulfuric acid soln. 4 of a concn. of >=70wt.% to change the copper on the substrate to copper sulfide, which is separated. The copper sulfide 3 settled in the aq. sulfuric acid soln. 4 is recovered by filtering. The other method consists in immersing the glass epoxy substrates 1 at >=40 to <60 deg.C in the aq. sulfuric acid soln. 4 of the concn. of >=70wt.%, then peeling the copper from the substrate and recovering the copper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering copper from waste printed circuit boards.

[0002]

2. Description of the Related Art In recent years, an increase in the amount of discarded home electric appliances has become a social problem. One of the main causes is the difficulty in recycling printed circuit boards contained in products. Since a printed circuit board is a composite material to which metal, plastic, and glass are firmly attached, it is very difficult to separate them. Therefore, at the time of disposal, there is no other choice but to crush it with a shredder or the like and dispose of it in landfill, causing an increase in the amount of discarded home electric appliances. Therefore, if a technology for separating metal, plastic, and glass from a waste printed circuit board is established, it will greatly contribute to the reduction in the amount of waste home appliances. Further, a large amount of copper, which is a valuable metal, is contained on a printed circuit board, and if this can be recovered, it is very effective in saving resources. Therefore, it is required to establish a method of separating metal, plastic, and glass from a waste printed circuit board and recovering copper.

At present, several methods for recovering copper from waste printed circuit boards have been proposed. The following are representative ones. "Development of recycling technology for component mounted printed circuit boards"
The recovery method described in (Surface Mount Technology January 1996) separates the mounted parts of the printed circuit board by heating and impact, and then recovers copper from the crushed waste printed circuit board by specific gravity separation and electrostatic separation. Is the way. This method has a problem that a large-scale apparatus is required, the cost required for recovery is large, and glass powder and resin are mixed in the recovered copper.

[0004] The recovery method described in the "Report of the 1995" Metals and Plastics Separation Technology Research Group "" (Resource Recycling System Center) uses a method of separating the mounted components by heating and impact, and then grinding the waste printed circuit boards. This is a method in which copper is dissolved and separated from the substrate by immersion in a sulfuric acid aqueous solution, and copper dissolved in the sulfuric acid aqueous solution is recovered by electrolytic recovery or chemical precipitation recovery. In this method, when copper is separated from the substrate, expensive hydrogen peroxide must be continuously added to the aqueous sulfuric acid solution, and there is a problem that the cost for the solvent is large. Further, in the copper recovery process, the electrolytic recovery has a problem that enormous costs are required for capital investment and operation of the apparatus. On the other hand, in the recovery of the chemical precipitate, the sulfuric acid aqueous solution and the alkali of the neutralizing agent are consumed during the neutralization, so that there is a problem that the cost required for consumables is large.

[0005]

The method of recovering copper from a waste printed circuit board which has been conventionally proposed has a problem that the cost required for recovery is enormous and lacks practicality as described above. . An object of the present invention is to provide a method for easily and inexpensively recovering copper from a waste printed circuit board, particularly a glass epoxy board.

[0006]

Means for Solving the Problems In order to solve the above problems, a first method of the present invention is to prepare a glass epoxy substrate having at least a copper foil on a surface thereof at a temperature of 60.degree.
The copper on the glass epoxy substrate is collected by immersing in a sulfuric acid aqueous solution containing 70% by weight or more of sulfuric acid heated to a temperature lower than 70 ° C. and collecting the generated copper sulfide by filtration. In the second method of the present invention, a glass epoxy substrate having at least a copper foil disposed on a surface thereof is heated to 40 ° C. or more and 60 ° C.
The copper on the glass epoxy substrate is recovered by immersing it in a sulfuric acid aqueous solution containing 70% by weight or more of sulfuric acid heated to less than 10%, and then recovering the copper separated from the substrate. In the above method, prior to immersing the glass epoxy substrate in the aqueous sulfuric acid solution, it is preferable to scrape the electrode surface on which the copper foil is disposed on the surface into fragments and immerse the fragments into the aqueous sulfuric acid solution.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Since concentrated sulfuric acid has a strong oxidizing power at a high temperature of about 200 ° C. or higher, it is generally known to dissolve copper. In the first method of the present invention, by adjusting the sulfuric acid concentration and the sulfuric acid temperature in the aqueous sulfuric acid solution to make the oxidizing power of the aqueous sulfuric acid solution lower than that described above, copper is converted into copper sulfide without dissolving and precipitated. A method of filtering and separating copper from a substrate. According to this method, at least a waste printed board on which a copper foil is disposed
When immersed in an aqueous sulfuric acid solution of 70% by weight or more heated to a temperature of less than 130 ° C., copper on the substrate is oxidized into cupric oxide in the form of solid powder, and falls off in the aqueous sulfuric acid solution to be separated from the substrate. At this time, the solder is dissolved in the aqueous sulfuric acid solution and separated from the substrate. Next, copper on the glass epoxy substrate is recovered by filtering and separating the cupric oxide precipitated at the bottom of the aqueous sulfuric acid solution. In this method, when copper is separated from the substrate, only inexpensive sulfuric acid is used as a solvent, so that the cost for the solvent is low. Also, in the copper recovery step, copper can be easily recovered by filtration and separation, so that large-scale equipment such as electrolytic recovery is not required, and there is no solvent consumption required for neutralization such as chemical precipitation recovery.

In the second method of the present invention, the oxidizing power of the aqueous solution of sulfuric acid is made lower than that of the first method, and only the epoxy resin adhering the copper to the glass cloth of the base material without oxidizing the copper is used. This is a method of separating the copper from the substrate by oxidizing and dissolving the epoxy into the aqueous sulfuric acid solution, thereby reducing the adhesive force between the substrate and the copper. According to this method, at least the waste printed circuit board on which the copper foil is disposed on
When immersed in a 70% by weight or more aqueous sulfuric acid solution heated to 70 ° C. or more and less than 60 ° C., all the epoxy of the substrate resin is eluted in the sulfuric acid, and copper can be peeled and collected from the glass cloth. In this method, when copper is separated from the substrate, only inexpensive sulfuric acid is used as a solvent, so that the cost for the solvent is low. Further, since copper can be recovered by peeling in the copper recovery step, a large-scale facility is not required, and there is no consumption of a solvent for neutralization. Further, since copper can be recovered as it is, recycling of copper is easier and more preferable than the first method.

Further, in the first and second methods, at least a copper electrode portion of a glass epoxy substrate having a copper foil disposed on a surface thereof is used by using a fragment obtained by thinly shaving the same, whereby epoxy resin of a substrate resin treated with a sulfuric acid aqueous solution is used. Decrease the amount of As a result, the amount of epoxy eluted in the aqueous sulfuric acid solution is reduced, and the life of the aqueous sulfuric acid solution is extended, so that the cost for the solvent is lower than in the first and second methods, which is more preferable.

[0010] When conditions other than those described in the present invention are used, the following problems may occur, so that they are not suitable as a method for recovering copper from a glass epoxy substrate of the present invention. 1) Regarding the sulfuric acid concentration: In the first method of the present invention,
When the concentration of sulfuric acid in the aqueous sulfuric acid solution is less than 70% by weight, the copper on the substrate does not change to copper sulfide and copper cannot be precipitated and separated from the substrate. In the second method of the present invention, the concentration of sulfuric acid in the aqueous sulfuric acid solution is reduced. If the content is less than 70% by weight, the epoxy of the substrate resin is not completely eluted in the aqueous sulfuric acid solution, and copper cannot be separated from the substrate.

2) Regarding the sulfuric acid immersion temperature: In the first method of the present invention, when the immersion temperature in the sulfuric acid aqueous solution is lower than 60 ° C., the copper on the substrate does not change into copper sulfide, and the copper cannot be precipitated and separated from the substrate. . On the other hand, when the immersion temperature is 130 ° C. or higher, copper becomes copper sulfate and dissolves in the sulfuric acid aqueous solution.
Copper cannot be recovered by filtration. In the second method of the present invention, when the immersion temperature in the aqueous sulfuric acid solution is less than 40 ° C., the epoxy of the substrate resin does not sufficiently elute, and copper cannot be completely removed from the glass cloth. When the immersion temperature is 6
When the temperature is 0 ° C. or higher and lower than 130 ° C., the copper on the substrate is changed to copper sulfide, which is not suitable. Further, when the immersion temperature is 130
If the temperature is higher than ℃, copper is converted to copper sulfate and dissolved in the aqueous solution of sulfuric acid, so that copper cannot be recovered by filtration.

The glass epoxy substrate which is the object of the present invention may be a glass epoxy substrate having at least a copper foil on the surface of the substrate, and it does not matter whether soldering or component mounting is performed. In addition, when a resist is present on the copper foil, it is expected that it will hinder the separation and recovery of copper. However, since the resist is dissolved and separated during sulfuric acid immersion, it is not necessary to remove the resist in advance. Therefore, the present invention can be applied not only to a waste printed board in an electric appliance after use but also to an unmounted board or a mounted board which has become defective in a manufacturing process. However, in the case of component-mounted boards, components may separate during sulfuric acid immersion, causing problems such as mixing of chemical substances in the components into the sulfuric acid aqueous solution. Is desirable. Therefore, in the following embodiment, a glass epoxy substrate having a copper foil on a surface portion, on which a component is mounted, is heated to 220 ° C. and vibrated to separate the mounted component. Was used for processing.

[0013]

EXAMPLES Detailed examples and comparative examples of the present invention will be described below. Example 1 A glass epoxy substrate from which mounted components were separated was immersed in a 96% by weight aqueous sulfuric acid solution at 100 ° C. for 3 hours. As a result, all the copper on the substrate was changed to black copper sulfide, separated from the substrate, and precipitated in a sulfuric acid aqueous solution. on the other hand,
In the aqueous sulfuric acid solution, a large amount of the epoxy resin of the substrate was eluted into the aqueous sulfuric acid solution, so that the aqueous sulfuric acid solution became a black viscous substance and partially precipitated. The precipitate was filtered using a fluorine-based filter paper (Polyflon filter PF060: retained particle diameter: 6 μm, manufactured by Advantic Toyo) to recover the copper sulfide precipitate. However, since epoxy was partially mixed in the copper sulfide precipitate, a heat treatment was performed at 200 ° C. for 30 minutes to decompose the epoxy to obtain pure copper sulfide. In addition, by the above-mentioned filtration operation,
The sediment of the epoxy was removed, and the sulfuric acid aqueous solution was black, but had low viscosity, and could be reused.

Comparative Example 1 A glass epoxy substrate from which mounted components were separated was immersed in a 60% by weight aqueous sulfuric acid solution at 100 ° C. for 3 hours. As a result, the copper on the substrate did not change to copper sulfide and did not separate from the substrate. Since a large amount of the epoxy of the substrate resin was eluted in the aqueous sulfuric acid solution, the aqueous sulfuric acid solution became a black viscous substance and partially precipitated. Thus, when the sulfuric acid concentration in the aqueous sulfuric acid solution is less than 70% by weight,
Since the copper is not oxidized, the copper cannot be separated from the substrate.
The precipitated sulfuric acid solution was removed by filtering the aqueous sulfuric acid solution after the treatment using a fluorinated filter paper (Polyflon filter PF060: retaining particle diameter: 6 μm, manufactured by Advantic Toyo Co., Ltd.). Although it was black, its viscosity was low, and it could be reused.

Comparative Example 2 A glass epoxy substrate from which mounted components were separated was placed in a 96% by weight sulfuric acid aqueous solution at 30 ° C. for 3 hours.
Soaked for hours. As a result, the copper on the substrate did not change and did not separate from the substrate. Since a large amount of the epoxy of the substrate resin was eluted in the aqueous sulfuric acid solution, the aqueous sulfuric acid solution became a black viscous substance. Thus, the temperature of the aqueous sulfuric acid solution is 60
If the temperature is lower than ° C, copper cannot be separated from the substrate because copper is not oxidized.

Comparative Example 3 A glass epoxy substrate from which mounted components were separated was immersed in a 60% by weight aqueous sulfuric acid solution at 130 ° C. for 3 hours. As a result, the copper on the substrate turned into copper sulfate, dissolved in the aqueous sulfuric acid solution, and separated from the substrate. On the other hand, the sulfuric acid aqueous solution became a black viscous substance because a large amount of the epoxy of the substrate resin was eluted into the sulfuric acid aqueous solution. As described above, when the temperature of the aqueous sulfuric acid solution is 130 ° C. or higher, copper is dissolved in the aqueous sulfuric acid solution, so that the copper cannot be recovered by filtration.

<< Embodiment 2 >> A glass epoxy substrate from which mounted components were separated was placed in a 96% by weight sulfuric acid aqueous solution at 60 ° C. for 2 hours.
Dipped for 0 hours. As a result, the copper on the substrate did not change to another compound, and the end was in a state of rising. On the other hand, the sulfuric acid aqueous solution became a black viscous substance because all of the epoxy of the substrate resin was eluted. Next, the end of the copper was pinched with tweezers and peeled off, whereby copper could be peeled and collected from the substrate. The treated sulfuric acid aqueous solution was washed with a fluorine-based filter paper (Polyflon filter PF060: retaining particle size 6).
The precipitate was removed by filtration using a μm filter (manufactured by Advantic Toyo Co., Ltd.), and although the sulfuric acid aqueous solution was black, its viscosity was low, and it could be reused.

Comparative Example 4 A glass epoxy substrate from which mounted components were separated was placed in a 60% by weight sulfuric acid aqueous solution at 60 ° C. for 2 hours.
Dipped for 0 hours. As a result, the copper on the substrate did not change to another compound. However, since the epoxy of the substrate resin hardly eluted and remained on the substrate, the adhesive force between the substrate and copper was strong and the copper did not float, so that the copper could not be peeled off the substrate with tweezers. Thus, when the sulfuric acid concentration in the aqueous sulfuric acid solution is less than 70% by weight,
The epoxy of the substrate resin is not completely eluted in the aqueous sulfuric acid solution,
Copper cannot be peeled off from the substrate.

Comparative Example 5 A glass epoxy substrate from which mounted components were separated was placed in a 96% by weight aqueous sulfuric acid solution at 30 ° C. for 2 hours.
Dipped for 0 hours. As a result, the copper on the substrate did not change to another compound. However, since the epoxy of the substrate resin hardly eluted and remained on the substrate, the adhesive force between the substrate and copper was strong and the copper did not float, so that the copper could not be peeled off the substrate with tweezers. As described above, when the temperature of the sulfuric acid aqueous solution is lower than 40 ° C., the epoxy of the substrate resin is not completely eluted in the sulfuric acid aqueous solution, so that copper cannot be peeled and collected from the substrate.

Comparative Example 6 A glass epoxy substrate from which mounted components were separated was placed in a 96% by weight sulfuric acid aqueous solution at 70 ° C. for 2 hours.
Dipped for 0 hours. As a result, the epoxy of the substrate resin was completely eluted in the aqueous sulfuric acid solution. However, the copper on the substrate changed to copper sulfide and precipitated at the bottom of the aqueous sulfuric acid solution, so that the copper could not be separated and recovered. As described above, when the temperature of the aqueous sulfuric acid solution is 60 ° C. or higher and lower than 130 ° C., the copper on the substrate is changed to copper sulfide, and thus the copper cannot be peeled and collected from the substrate.

Comparative Example 7 A glass epoxy substrate from which mounted components were separated was immersed in a 96% by weight aqueous sulfuric acid solution at 140 ° C. for 20 hours. As a result, the epoxy of the substrate resin was completely eluted in the aqueous sulfuric acid solution. However, since the copper on the substrate became copper sulfate and was dissolved in the aqueous sulfuric acid solution, the copper could not be peeled and collected. As described above, when the temperature of the sulfuric acid aqueous solution is 130 ° C. or higher, the copper on the substrate is dissolved in the aqueous sulfuric acid solution, so that copper cannot be peeled and collected from the substrate.

<< Embodiment 3 >> This embodiment will be described with reference to FIG. The surface including the copper electrode 2 of the glass epoxy substrate 1 from which the mounted components are separated is 0.3 m thick using an electric plane.
m. Thus, the fragment 1 including the copper electrode 2
a was obtained. This fragment 1a was immersed in a 96% by weight aqueous sulfuric acid solution 4 in a container 5 at 100 ° C. for 3 hours. As a result, all the copper on the substrate becomes black copper sulfide, separated from the substrate,
Precipitated in aqueous sulfuric acid. This precipitate 3 could be recovered by filtration using a fluorine-based filter paper. The amount of the substrate resin eluted was smaller than that of Example 1, and the sulfuric acid aqueous solution was a low-viscosity substance just turned brown, so that it could be reused. As described above, in the present embodiment, the amount of epoxy used for the sulfuric acid treatment is smaller than that in the first embodiment, and the sulfuric acid aqueous solution after the treatment can be reused without being filtered. However, as the number of treatments increases, the aqueous sulfuric acid solution becomes viscous and starts to precipitate,
After a certain number of treatments, it is necessary to perform filtration.

<< Embodiment 4 >> The surface including the copper electrode of the glass epoxy substrate from which the mounted components were separated was
The slice was sliced to a thickness of about 0.3 mm. The obtained fragments are
It was immersed in a 96% by weight aqueous sulfuric acid solution at 60 ° C. for 20 hours. As a result, the copper on the substrate was not changed to another compound, and the end was in a raised state. Therefore, the end could be picked up with tweezers and peeled off, so that the copper could be separated and collected from the substrate. On the other hand, in the sulfuric acid aqueous solution, all of the epoxy of the substrate resin was eluted in the sulfuric acid aqueous solution. However, since the amount of the epoxy eluted was smaller than that in Example 2, it became a brown low-viscosity substance and could be reused. . As described above, in the present embodiment, the amount of epoxy used for the sulfuric acid treatment is smaller than in the second embodiment, and the sulfuric acid aqueous solution after the treatment can be reused without being filtered. However, as the number of treatments increases, the aqueous sulfuric acid solution becomes viscous and starts to precipitate, so that it is necessary to perform filtration every certain number of treatments.

As described above, as shown in Examples 1 to 4, by using the method for recovering copper from a glass epoxy resin substrate of the present invention, copper can be separated from a waste printed circuit board.
Can be recovered. In particular, in the methods shown in Example 3 and Example 4, since the amount of eluted epoxy is small, the frequency of filtration of the sulfuric acid aqueous solution after the treatment is low, and the treatment cost is low. It is more preferable as a method for recovering copper. Example 3 and Example 4
Which should be selected may be determined in consideration of which one of the sulfuric acid temperature and the processing time is more important. As described in Examples 1 to 4, the sulfuric acid aqueous solution can be reused by filtration. However, if the number of treatments exceeds a certain number of times, the sulfuric acid aqueous solution is deteriorated and cannot be reused by filtration. Need to be disposed of. At this time, since the solder on the substrate is dissolved in the sulfuric acid aqueous solution and contains harmful lead, the solder is neutralized using a neutralizing agent such as sodium hydroxide or potassium hydroxide to remove the solder. It must settle and be collected by filtration.

[0025]

As described above, the present invention provides a method for easily and inexpensively recovering copper from waste printed circuit boards without requiring large-scale equipment and expensive consumables such as solvents. It greatly contributes to resource saving and waste reduction.

[Brief description of the drawings]

FIG. 1 is a view showing a processing step of a substrate in an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass epoxy board 1a Fragment containing copper electrode 2 Copper electrode 3 Precipitation of copper sulfide 4 Sulfuric acid aqueous solution 5 Processing vessel

Claims (3)

[Claims] 1. A glass epoxy substrate having at least a copper foil disposed on a surface thereof is immersed in a sulfuric acid aqueous solution having a concentration of 70% by weight or more at a temperature of 60 ° C. or more and less than 130 ° C. to sulphide copper on the substrate. A method for recovering copper from a glass epoxy substrate, comprising: a step of converting into copper and separating; and a step of recovering copper sulfide precipitated in the aqueous sulfuric acid solution by filtration. 2. a step of immersing a glass epoxy substrate having at least a copper foil disposed on a surface thereof in a sulfuric acid aqueous solution having a concentration of 70% by weight or more at a temperature of 40 ° C. or more and less than 60 ° C.
And recovering copper from the glass epoxy substrate by peeling copper from the substrate after immersion. 3. The glass according to claim 1, further comprising, prior to immersing the glass epoxy substrate in the aqueous sulfuric acid solution, shaving the electrode surface on which a copper foil is disposed on the surface into pieces. A method for recovering copper from epoxy substrates.