JP5067389B2 - Solder paste recycling method and apparatus - Google Patents

Description

  The present invention relates to a solder paste recycling method and apparatus.

  As a method for soldering electronic components, there are a brazing method, a flow method, a reflow method, and the like. Among them, in the reflow method, a solder paste is printed and applied to a necessary portion of a printed circuit board, an electronic component is mounted, heat is applied by a heating device such as a reflow furnace, and the solder paste is melted and soldered.

  The solder paste used in the reflow method is produced by kneading fine solder alloy particles, a paste-like flux component, and an organic solvent. In general, the solder paste is distributed in a cylindrical plastic container. The user scoops out the solder paste from the container with a spatula and applies it to the printed circuit board.

  When the viscosity of the solder paste increases due to the volatilization of the organic solvent that is a component, the printing state deteriorates. Therefore, all the solder paste in the container has been used up and discarded after a certain period of time has elapsed since opening. However, a method of extracting solder alloy particles that can be reused from the solder paste to be discarded and recycling the solder paste has attracted attention against the background of the demand for reduction of industrial waste and the rising price of the metal market.

  Here, the solder paste recycling method includes a melting method. In the melting method, a solder paste and a plastic container are put into a large iron kettle, and the solder paste etc. charged into the kettle is melted at 400 to 500 ° C. by heating with a burner from the bottom of the kettle. . When heated at 400 to 500 ° C., both the plastic container and the solder paste are melted, but only the solder alloy component is recovered by utilizing the difference in specific gravity and recycled as an ingot alloy.

  Further, since the flux component contained in the solder paste can suppress the generation of dioxins if incinerated at a temperature of 800 ° C. or higher, the solder paste is melted and recycled at a temperature of 800 ° C. or higher by using a heating means (for example, patents). Reference 1).

JP-A-11-229048

  However, in the conventional solder paste recycling method, the solder paste containing the flux component is melted, so the flux component kneaded in the solder paste (containing about 10% by weight) burns and carbonizes. There is a problem that black smoke is generated and a bad odor is generated.

  The present invention has been made to solve the above-described problems, and provides a method and apparatus for recycling solder paste without producing black smoke or bad odor.

  The solder paste recycling method according to the present invention includes a step of rapidly freezing the solder paste and a step of separating and extracting the solder alloy particles from the frozen solder paste.

  The present invention has been made to solve the above-described problems. After the solder paste is rapidly frozen to remove the flux component and the organic solvent, the solder alloy particles are melted to recycle the solder paste. Therefore, the solder paste can be recycled without generating black smoke or bad odor.

It is a flowchart which shows the solder paste recycling method in Embodiment 1 of this invention. It is the figure which modeled a mode that the solder paste in Embodiment 1 of this invention self-pulverized by quick freezing. It is a figure explaining the process of isolate | separating a solder alloy particle from the solder paste in Embodiment 1 of this invention. It is a top view which shows the surface shape of the separating plate in Embodiment 1 of this invention. It is a figure explaining the process of melt | dissolving the solder alloy particle in Embodiment 1 of this invention, and producing | generating a solder alloy ingot. It is a figure explaining the process of fuse | melting the solder alloy particle in Embodiment 2 of this invention. It is a figure explaining the process of isolate | separating the solder alloy particle in Embodiment 3 of this invention.

  Embodiments of a solder paste recycling method and apparatus according to the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals indicate the same or corresponding configurations.

Embodiment 1 FIG.
FIG. 1 is a flowchart showing a method of recycling solder paste as recycled solder in Embodiment 1 of the present invention. FIG. 2 is a diagram schematically showing a state in which the solder paste according to Embodiment 1 of the present invention is self-pulverized by rapid freezing. FIG. 2A shows a solder paste before quick freezing, and FIG. 2B shows a solder paste after quick freezing. FIG. 3 is a diagram illustrating a process of separating solder alloy particles from the solder paste in the first embodiment of the present invention.

  In the solder paste recycling method according to the first embodiment, first, the solder paste 1 is rapidly frozen (step S10). By rapid freezing, the flux component 2 and the organic solvent 10 kneaded in the solder paste 1 are rapidly solidified and expanded, so that the kneaded state collapses and the solder alloy particles 3 are partially separated. (See FIG. 2 (b)). The solder paste in which the solder alloy particles 3 are partially separated by rapid freezing is referred to as frozen solder paste 1a.

  Next, the frozen solder paste 1a is finely pulverized (step S20). The frozen solder paste 1a is crushed by applying a physical impact to the frozen solder paste 1a, such as being crushed with a hammer, or by applying the high pressure by enclosing the frozen solder paste 1a in a pressure vessel. In step S20, the solder paste 1b in which the solder alloy particles 3 are further separated from the frozen solder paste 1a is generated. This solder paste is referred to as pulverized solder paste 1b.

  Next, the solder alloy particles 3 are separated and extracted from the pulverized solder paste 1b using the separation device 4 having the separation plate 40 having a groove on the surface (step S30). The separation device 4 inclines the separation plate 40 at a predetermined angle and swings it at a predetermined frequency and amplitude. As shown in FIG. 3A, the pulverized solder paste 1 b is disposed on the separation plate 40. At this time, the inclination angle of the separation plate 40 is optimally 15 ° to 30 °. Next, as shown in FIG. 3B, the separation device 4 swings the separation plate 40 in the direction of the arrow to separate the solder alloy particles 3 from the other components (flux component 2 and organic solvent 10). To do. Since the specific gravity of the solder alloy particles 3 is larger than that of the other components, the solder alloy particles 3 move downward along the inclined surface of the separation plate 40.

  Regarding the oscillation of the separation plate 40, the frequency is set within a range of 10 to 240 Hz and the amplitude is set within a range of 1 to 5 mm. Specific numerical values are determined by the particle size of the solder alloy particles 3, the contents of the flux component 2 and the organic solvent 10. For example, the larger the particle size of the solder alloy particles 3, the lower the frequency. The swinging direction of the separation plate 40 is not limited to the direction indicated by the arrow in FIG. 3B, and the separation plate 40 may be swung in the vertical direction or in the vertical direction with respect to the paper surface. .

  FIG. 4 is a plan view showing the surface shape of separation plate 40 according to Embodiment 1 of the present invention. The shape of the groove | channel in the surface which contacts the grinding | pulverization solder paste 1b is shown. 4A shows a linear groove, FIG. 4B shows a wave-like groove, and FIG. 4C shows a bowl-like groove. About the shape and dimension of a groove | channel, an optimal thing is selected based on the kind of grinding | pulverization solder paste 1b.

  FIG. 5 is a diagram for explaining a process of producing solder alloy ingot 9 by melting solder alloy particles 3 in the first embodiment of the present invention. After separating the solder alloy particles 3 in step S30, the extracted solder alloy particles 3 are put into the solder bath 6 and melted (step S40). The solder bath 6 is a heating bath having a tap 7 at the lower portion, and in the bath, solder having the same alloy composition as the separated solder alloy particles 3 is melted. The melting temperature is about 30 to 70 ° C. higher than the melting point of the alloy. For example, in the case of eutectic solder containing lead, the melting temperature is set to 250 ° C.

  The solder alloy particles 3 put into the solder bath 6 are completely melted in the same manner as the molten solder 5. Solder completely melted from the hot water outlet 7 is poured into the ingot mold 8 and appropriately cooled to produce the solder alloy ingot 9 (step S50).

  According to Embodiment 1 of the present invention, after removing the flux component 2 and the organic solvent 10 from the solder paste 1, the solder alloy particles 3 are melted to produce the solder alloy ingot 9. Solder paste can be recycled without generation.

Embodiment 2. FIG.
In the process of melting the solder alloy particles 3, the solder tank 6 is used in the first embodiment. However, in the second embodiment, a melting apparatus capable of setting environmental conditions for melting is used. FIG. 6 is a diagram illustrating a process of melting the solder alloy particles 3 in the second embodiment of the present invention.

  Since the process of rapidly freezing the solder paste 1, the process of separating the solder alloy particles 3, and the process of generating the solder alloy ingot 9 from the molten solder 5 are the same as those in the first embodiment, the description thereof is omitted. Below, the process of melting the solder alloy particles 3 will be described.

  The melting apparatus 20 covers the solder bath 6 with a hood 21, and includes an inlet 22 for introducing a substance to be melted, a nitrogen inlet 23 for injecting nitrogen, an exhaust hole 24 for exhausting the inside of the hood 21, and a hot water outlet 7. I have. The melting device 20 can adjust the oxygen concentration inside the hood 21 by injecting nitrogen from the nitrogen inlet 23. Impurities due to oxidation are likely to be generated on the surface portion (air contact surface) of the molten solder 5. Therefore, in order to lower the oxygen concentration in the vicinity of the surface of the molten solder 5, it is desirable to inject nitrogen into the hood 21 from the nitrogen inlet 23 so that the oxygen concentration is 500 ppm or less. By providing the nitrogen inlet 23 at a height close to the surface of the molten solder 5, the nitrogen concentration near the surface of the molten solder 5 can be increased, that is, the oxygen concentration near the surface of the molten solder 5 can be decreased.

  The nitrogen inlet 23 has a structure for heating the nitrogen to be injected. With this structure, nitrogen injected from the nitrogen injection port 23 does not lower the temperature of the surface portion of the molten solder 5, and the generation of impurities in the surface portion of the molten solder 5 can be suppressed. A suitable heating temperature of nitrogen is about 80 to 150 ° C.

  When the flux component 2 is adhered to the separated and extracted solder alloy particles 3 in a small amount, it is considered that black smoke and odor are generated in a small amount due to melting of the solder alloy particles 3. In such a case, the gas staying in the hood 21 can be exhausted from the exhaust hole 24.

  According to the second embodiment of the present invention, as in the first embodiment, after the flux component 2 and the organic solvent 10 are removed from the solder paste 1, the solder alloy particles 3 are melted to produce the solder alloy ingot 9. Solder paste can be recycled without generation of black smoke or odor.

  In addition, according to the second embodiment of the present invention, the melting of the solder alloy particles 3 can be performed in an environment having a lower oxygen concentration than in the atmosphere by using the melting device 20, so that the purity is high with less contamination of impurities. A solder alloy ingot 9 can be produced.

Embodiment 3 FIG.
In the first embodiment, the separation plate 40 of the separation device 4 is singular. However, in the third embodiment, the separation device 4 has a plurality of separation plates 40a and 40b, and the separation plates 40a and 40b are respectively separated. The tilt angle, frequency, amplitude, etc. can be set. FIG. 7 is a diagram for explaining a process of separating the solder alloy particles 3 in the third embodiment of the present invention.

  The step of rapidly freezing the solder paste 1, the step of melting the solder alloy particles 3, and the step of generating the solder alloy ingot 9 from the molten solder 5 are the same as those in the first embodiment or the second embodiment. Omitted. Below, the process of isolate | separating the solder alloy particle 3 is demonstrated.

  The separation device 4 includes a plurality of separation plates 40a and 40b connected to each other. The separation plates 40a and 40b may be a combination having different groove shapes on the surface. Further, the separation device 4 can set the inclination angle, the frequency, and the amplitude of the plurality of separation plates 40a and 40b, respectively. The vibration direction can also be set.

  The particle diameter of the solder alloy particles 3 contained in the pulverized solder paste 1b is not uniform. It is desirable to set various parameters of the separation device 4 (frequency, amplitude, etc. of the separation plate) to optimum values according to the particle size of the solder alloy particles 3. For example, in the separation plate 40a, various parameters are set to values suitable for separating the solder alloy particles 3 having a relatively large particle size, and in the separation plate 40b, the solder alloy particles 3 having a relatively small particle size are separated. Set various parameters to values suitable for Thereby, the solder alloy particles 3 having different particle diameters can be accurately separated.

  In the third embodiment, the separation device 4 includes a plurality of separation plates 40a and 40b, and the inclination angles of the separation plates 40a and 40b can be set. However, the plurality of separation plates 40a and 40b are not necessarily provided. It is not necessary. When selecting the thing with the same groove | channel shape of the separating plates 40a and 40b, the separating apparatus 4 does not need to be provided with the several separating plates 40a and 40b. Rather than setting various parameters for each of the plurality of separation plates 40a, 40b, when separating and extracting the solder alloy particles 3 using one separation plate 40, various parameters corresponding to different particle sizes are set. Any configuration can be used.

  According to the third embodiment of the present invention, as in the first embodiment, after the flux component 2 and the organic solvent 10 are removed from the solder paste 1, the solder alloy particles 3 are melted to produce the solder alloy ingot 9. Solder paste can be recycled without generation of black smoke or odor.

  Further, according to the third embodiment of the present invention, it is possible to set not only one type of frequency, amplitude, groove shape and the like of the separation plate, but also accurately separate the solder alloy particles 3 having different particle sizes. be able to.

DESCRIPTION OF SYMBOLS 1 Solder paste 1a Frozen solder paste 3 Solder alloy particle 4 Separation device 6 Solder tank 9 Solder alloy ingot 20 Melting device 21 Hood 23 Nitrogen inlet 40, 40a, 40b Separation plate

Claims (7)

Freezing the solder paste;
Separating and extracting solder alloy particles from frozen solder paste;
A solder paste recycling method comprising:   The solder alloy particles are separated and extracted by placing the frozen solder paste on a separation plate having a plurality of grooves on the surface and swinging the separation plate. Solder paste recycling method. Melting the extracted solder alloy particles;
Producing a solder alloy ingot from the molten solder alloy particles;
The solder paste recycling method according to claim 1, wherein the solder paste recycling method is provided.   4. The solder paste recycling method according to claim 3, wherein the extracted solder alloy particles are melted in an environment having a lower oxygen concentration than the atmosphere. A separation plate having a plurality of grooves on the surface;
A separation device for separating and extracting solder alloy particles from a frozen solder paste by swinging the separation plate. A plurality of the separation plates are connected and provided,
6. The separation apparatus according to claim 5, wherein an inclination angle, a frequency, and an amplitude of the separation plate are set for each separation plate. A separation device for separating and extracting solder alloy particles from a frozen solder paste by swinging a separation plate having a plurality of grooves on the surface;
A solder bath to melt the solder alloy particles by heating,
A hood covering the solder bath;
A nitrogen inlet for injecting nitrogen into the portion close to the surface of the solder alloy particles melted in the solder bath,
A solder paste recycling apparatus that melts the solder alloy particles in an environment having a lower oxygen concentration than the atmosphere by injecting the nitrogen.

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