JP4403681B2 - Impurity removal method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention Impurity removal method More specifically, in a flow type soldering apparatus that is used when soldering an electronic component to a substrate, etc., and soldering by bringing a flow of solder material that has been heated and melted into contact with a soldering point, the work progresses. Accompanying the removal of impurities that increase in the solder material method It is targeted.
[0002]
[Prior art]
The flow type soldering apparatus can be efficiently soldered, and is widely used as a method suitable for industrial production.
In the flow type soldering apparatus, a solder material is heated and melted in a solder tank. This solder material in a fluid state is sprayed onto the surface of the board on which the electronic component is to be soldered, or the substrate is brought into contact with the liquid surface of the solder material, and the solder material is supplied to the soldering portion between the electronic component and the board. And solder.
When the flow type soldering apparatus is operated for a long time, there is a problem that impurities contained in the solder material in the solder tank increase, which adversely affects the quality performance of soldering.
[0003]
When the heated and melted solder material comes into contact with the electronic component or the substrate, for example, low melting point components such as Pb and Bi are eluted from the lead plating portion of the electronic component and are contained as impurities in the solder material in the solder tank. Sometimes. Cu may be eluted from the copper foil of the substrate. In addition, the low melting point component contained in the material constituting the electronic component or the substrate is eluted, and impurities contained in the solder material increase.
When the impurities contained in the solder material increase, the uniformity of the solder is lost and the quality performance of the soldering deteriorates. Specifically, for example, a phenomenon called lift-off occurs in which the interface between the solder and the substrate copper foil is peeled off at a soldering point. Further, when the Cu concentration of the solder material is increased, the melting point of the solder material is increased, the viscosity is increased, bridge defects and red-eye defects are increased, and work quality is deteriorated. Pb is a constituent component such as Sn-Pb solder, but in the case of a solder material aiming at lead-free, it will inhibit lead-free.
[0004]
Therefore, in the conventional flow type soldering technology, a certain period of operation is performed, and all the solder material having an increased impurity concentration is taken out from the solder tank and discarded, and new solder material is supplied to the solder tank. ing.
[0005]
[Problems to be solved by the invention]
It is not economical to discard all the solder material having a high impurity concentration, which increases the work cost of the soldering operation and the manufacturing cost of the electronic device manufactured by soldering. In addition, the labor and cost for disposal of a large amount of solder material are large. In particular, the soldering operation must be completely interrupted during the solder material replacement operation. The operation of the entire production line of electronic devices including soldering work must be stopped, and the economic loss is great.
Accordingly, an object of the present invention is to efficiently remove impurities in the solder material that increase with operation in the above-described flow soldering technique.
[0006]
[Means for Solving the Problems]
The impurity removal method according to the present invention detects the amount of impurities contained in a solder material in a solder tank of a flow soldering apparatus, and removes the solder material containing impurities when the amount of impurities exceeds a specified value. For the solder material that is melted by the heating of n (n is an integer of 2 or more) heaters disposed from one end side to the other end side of the processing tank, the step (a) for transporting from the tank to the processing tank, The first heater is energized to heat and melt the solder material, the first heater is stopped, and the second heater is energized to heat and melt the solder material, and the second heater is stopped and the third heater is heated. And the solder material is heated and melted. Thereafter, the heaters in the arrangement order are repeatedly stopped and energized in order from one end side to the other end side of the treatment tank, and the (n-1) th heater is stopped. Through the nth heater And step (b) for heating and melting the solder material and, Impurities transferred from one end side to the other end side of the treatment tank by the step (b) are included, and the n th heater (C) removing the melted solder material from the treatment tank, heating and melting the solder material remaining in the treatment tank, and returning it to the solder tank of the flow soldering apparatus.
[0007]
[Flow type soldering equipment]
The present invention can be applied to a flow type soldering apparatus having a normal structure.
The flow-type soldering apparatus heats and melts a solder material and brings the solder material in a fluidized state into contact with a soldering portion, thereby soldering an object to be soldered. As long as it has such a basic function, the specific device structure and operation method are not particularly limited.
As a basic structure, a solder tank is provided. The solder tank can be provided with a heating means for heating the solder material. An electric heater, an electromagnetic induction heater, or the like is used as the heating means for the solder tank. The solder tank may be provided with a pump that stirs the solder material or forms a flow of the solder material.
[0008]
The flow type soldering equipment has a structure that transports soldering objects such as substrates with electronic components, a structure that holds soldering objects, and a structure that guides the flow of solder material to the soldering location. I can keep it.
[Solder material]
Various solder materials used in normal flow soldering technology can be used.
Specifically, Sn—Pb solder, Sn—Cu solder, Sn—Ag—Cu solder, and the like can be given. The present invention is effective in preventing Pb from accumulating as an impurity in a solder material in lead-free solder.
[0009]
Solder materials have different melting points depending on their composition. For example, Sn—Pb eutectic solder is about 183 ° C. It is desirable to adjust the heating conditions in the impurity removal process according to the melting point of the solder material.
[Impurity treatment tank]
In order to perform the impurity removal work, the solder material in the solder tank is fed in and the solder material is accommodated during the impurity removal process.
Basically, it is only necessary to have a material and a structure capable of accommodating a heat-melted solder material, like the solder tank.
[0010]
The impurity treatment tank can be provided with a discharging means for discharging the solder material in the portion where the impurities are accumulated. Specifically, a drain pipe can be provided in a portion of the impurity treatment tank where the solder material in the portion where the impurities are accumulated accumulates. The solder material can be discharged manually by using the above-described handle.
In addition to the local heating means described later, the impurity treatment tank may be provided with a heating means that can heat the solder material in the entire treatment tank. This whole heating means can adopt the same structure as that of the solder tank heating means.
[Transportation means]
A transfer means capable of transferring the solder material is provided between the impurity treatment tank and the solder tank.
[0011]
The transfer means can be provided with a means for supplying the solder material containing impurities in the solder tank to the impurity treatment tank and a means for returning the solder material from which impurities have been removed in the impurity treatment tank to the solder tank. . Specifically, it can be manually transferred using a heat-resistant handle such as a handle, but it is automatically performed using a transfer path such as a pipe, a hose, and a hook and a fluid transfer device such as a pump. It is preferable that it can be transported to. It is also possible to transfer the solder material from the impurity treatment tank to the solder tank by moving or tilting the entire impurity treatment tank. As the material and structure of the transfer means, those having heat resistance capable of transferring the solder material heated and melted are used.
[0012]
[Local heating means]
Only a part of the solder material accommodated in the treatment tank is heated and melted. Basically, a heating means for a normal solder material is provided so as to heat only a relatively narrow fixed region.
The local heating means may be disposed in the internal space of the processing tank, may be embedded in a side wall or a bottom wall of the processing tank, or may be disposed so as to surround the outside of the processing tank.
As a specific heating mechanism, one having the same structure or principle as the above-described heating means for the solder tank or the entire processing tank can be adopted. Examples thereof include an electric heater and an electromagnetic induction heater. Infrared irradiation and radiation irradiation can also be employed. It is also possible to adopt a method of blowing hot air or banner combustion gas.
[0013]
The local heating means continuously moves the heating and melting position from one end side to the other end side of the processing tank.
Moving the solder melting position of the solder material can be realized, for example, by moving a heating source such as a heater. When heating with radiation such as laser, or when irradiating the combustion gas of a gas burner, the heating position can be changed by moving the irradiation position of the radiation. A plurality of heating sources can be driven in order or stopped so that the heating source that is being heated is switched without moving the heating source itself. Furthermore, the heating source may be fixed, and the heating position in the processing tank by the fixed heating source may be moved by moving the processing tank.
[0014]
The heating and melting position of the solder material is continuously moved from one end side to the other end side of the treatment tank. As a result, impurities having a melting point lower than that of the solder material are collected and accumulated in the liquid phase solder material that has been heated and melted, from the portion of the solder material that is solidified outside the heating and melting position. Impurities are removed from the portion of the solder material that has solidified into a solid phase.
This phenomenon, or the removal and accumulation of impurities, is known as a phenomenon in which when a metal solidifies, the solute (impurities) is pushed out into a solvent that is still in a molten state (original solder composition part) and concentrated. It has been. When the solid phase and the liquid phase coexist, the alloy component concentration on the solid phase side decreases, and the alloy component is concentrated in the liquid phase. As a technique that utilizes this phenomenon, a zone melting method that is conventionally used for the production or refining of high-purity metals is known.
[0015]
The removal effect of impurities can be adjusted by the moving speed of the heating and melting position. The faster the moving speed, the shorter the working time. The slower the moving speed, the more reliably the impurities are removed. An appropriate moving speed may be set in consideration of these conditions, the solder material, the type of impurities, the heating temperature, and the like. Specifically, it can be set in the range of 0.1 to 10 mm / min.
The removal effect of impurities can also be adjusted by the moving distance of the heating and melting position. As the moving distance is longer, impurities are sufficiently accumulated, but the moving time becomes longer and the treatment tank becomes larger. Usually, the moving distance can be set in the range of 150 to 500 mm, although it varies depending on the processing amount of the solder material and other processing conditions.
[0016]
The movement of the heating and melting position is usually moved in one direction linearly from the start point on one end side of the treatment tank to the end point on the other end side. After the heating and melting position reaches the end point, the movement can be repeated by returning to the start point. By repeating the movement in one direction, the removal of impurities in the solder material and the accumulation at the end can be performed more reliably, and the impurity removal efficiency of the finally obtained solder material is increased. Usually, it can be repeated in the range of 1 to 20 times.
Depending on the structure of the processing tank and the processing conditions, the heating and melting position may be moved in a zigzag manner or may be moved in a curved manner. It is also possible to move the heating and melting position in the circumferential direction in an annular processing tank.
[0017]
As a melting and solidification procedure, the whole is heated and melted and gradually solidified from one end, so that the center of the region that remains in the molten state is moved as the solidified region expands. it can.
[Multiple heaters]
As the local heating means, one in which a plurality of heaters are individually operated to move the heating and melting position is easy to manufacture and control the operation.
A rod heater can be used as the heater. The rod heaters can be arranged in parallel, and each rod heater can be connected to an electric power source, and a control panel and a control computer for controlling energization to the rod heater can be provided. If the start and stop of energization is controlled for each bar heater, the position of the bar heater that generates heat when energized becomes the heating and melting position of the solder material. By controlling the start and stop of energization, timing, energization time, supply power, and the like, the heating and melting state of the solder material and the moving state of the heating and melting position can be freely adjusted.
[0018]
As the heater, a plurality of annular heaters can be arranged in the axial direction of the processing tank so as to surround the outer periphery of the processing tank having a bottomed cylindrical shape. Heating can be performed uniformly from the entire circumference of the treatment tank. Since there is no heating mechanism inside the treatment tank, the treatment tank can be used widely. An electromagnetic induction heating coil can be used instead of the annular heater.
[Cooling means]
The impurity treatment tank can be provided with a cooling means for cooling the solder material. Solder material other than the portion heated by the local heating means can be quickly cooled. As a result, the impurities are rapidly transferred from the low temperature side to the high temperature side of the solder material, and the impurity removal on the low temperature side can be efficiently achieved.
[0019]
As a specific cooling means, a technique similar to a cooling device used in a normal mechanical device or the like can be applied. For example, a water cooling jacket apparatus can be used. A jacket apparatus using a cooling medium other than water can also be used. A method of blowing cold air can also be adopted.
The entire impurity treatment tank may be cooled at the same time, or the cooling position can be moved in accordance with the movement of the heating and melting position.
[Impurity sensor]
The presence and amount of impurities contained in the solder material are detected.
[0020]
Basically, the sensor structure and the detection principle are not particularly limited as long as the sensor can detect impurities in the molten metal used in a normal metal processing technique or the like.
Impurity sensors are used to identify and quantify impurities by measuring the temperature change over time when the workpiece is heated, changes in electrical characteristics such as resistance and dielectric capacitance, and magnetic changes. Can be used. Usually, impurities are detected from the difference in properties from a standard material that does not contain impurities.
If the impurity sensor detects impurities contained in the solder material in the solder tank, it is possible to monitor impurities that increase as the soldering operation proceeds. What is necessary is just to perform a necessary impurity removal process in the stage where the amount of impurities detected by the impurity sensor exceeds a preset reference value.
[0021]
The impurity sensor can also be installed in the impurity treatment tank to monitor the removal status of impurities in the solder material that is performing the impurity removal treatment. The impurity removal operation may be completed when the amount of impurities falls below the specified value. In the impurity treatment tank, an impurity sensor is provided at a position where the impurities are accumulated, and when it is detected that the impurities are concentrated to a certain level or more, the solder material in that portion can be discharged.
[Impurity removal method]
The impurity processing operation can be performed by temporarily interrupting the soldering operation by the flow type soldering apparatus, or the impurity removing operation can be performed in parallel while continuing the soldering operation.
[0022]
In the impurity removal operation, first, the solder material in the solder tank is sent to the impurity treatment tank. Next, using the local heating means, the solder material is locally heated and melted in the processing tank, and the heating and melting position is continuously moved from one end side to the other end side of the processing tank. By this treatment, the low melting point impurity contained in the solder material moves from one end side of the treatment tank to the other end side and is accumulated in the solder material on the other end side. Impurities are removed from the solder material present at other positions in the treatment tank.
Except for the solder material where the impurities are accumulated at the other end of the treatment tank, if the impurities are sufficiently removed for the solder material at other parts of the treatment tank, the solder material where the impurities are accumulated is The solder material discharged from the impurity treatment tank and from which impurities have been removed is sent back to the solder tank.
[0023]
The solder material in the portion where the impurities are accumulated can be discharged from a drain port or the like provided in the treatment tank in a heated and melted state. The discharged impurity-accumulating solder material can be discarded as it is, or can be sent to an active ingredient recovery or regeneration process.
In the solder tank, the solder material from which impurities have been removed is returned, so that the concentration of impurities in the entire solder tank is lowered and good soldering operation can be continued.
If the solder material stored in the solder tank is partially extracted and the impurity removal process is continuously performed, the solder material in the solder tank can always be maintained in a state with few impurities. The impurity removal process may be performed at regular intervals, or the impurity removal process may always be performed during operation of the flow soldering apparatus. The start time and execution interval of the impurity removal process may be determined based on the detection information of the impurity sensor installed in the solder tank. It is also possible to control the operation of the impurity removal processing based on the detection information of the impurity sensor by automatic control using a control computer or the like.
[0024]
[Confirmation of effect]
It was confirmed that the impurity removal of the solder material 50 can be performed satisfactorily using the impurity removal apparatus of the present invention.
An Su—Cu-based material was used as the solder material 50, and Bi, which is an impurity contained in the solder material 50, was removed using the impurity removing apparatus 10 shown in FIG. The solder material 50 before processing contains 5.0% Bi.
When the movement of the heating and melting position in the treatment tank 10 was repeated 20 times, the Bi concentration of the solder material 50 was reduced to 4.1% on the start point side of the movement and melting position in the treatment tank 10. The Bi concentration on the movement end point side was 6.7%. The Bi concentration at the midpoint of movement was 4.2%.
[0025]
Therefore, if only the solder material 50 near the movement end point is removed, Bi is efficiently removed from the solder material 50.
Similarly, Pb which is an impurity contained in the solder material 50 was removed. The solder material 50 before processing contains 0.5% Pb.
When the movement of the heating and melting position in the treatment tank 10 was repeated 15 times, the Pb concentration of the solder material 50 decreased to 0.29% on the start point side of the movement and melting position in the treatment tank 10. The Pb concentration on the movement end point side was 0.59%.
As a result, it was confirmed that impurity removal by the impurity removal apparatus 10 can be achieved with practically sufficient performance.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
The flow soldering apparatus shown in FIG. 1 includes an impurity removing apparatus 10.
[Flow type soldering equipment]
As a basic structure, a solder tank 20 that stores a solder material 50 in a molten state, a pump 22 that creates a forced flow in the solder material 50, a guide member 24 that guides the flow of the solder material 50, and the like. It has.
A board P to be soldered is disposed on the guide member 24, and the flow of the solder material 50 comes into contact with the surface of the board P, and predetermined solder such as fixing and electrical connection of electronic components mounted on the board P is provided. Installation work is performed. Although not shown, the solder tank 20 is provided with a heater for heating and melting the solder material 50. Moreover, the conveyance conveyor of the board | substrate P etc. are also provided.
[0027]
[Impurity sensor]
An impurity sensor 30 is installed in the solder tank 20. The impurity sensor 30 is provided with pipes 32 and 34 for transferring the solder material 50 to and from the solder tank 20. The impurity sensor 30 acquires information such as the fact that the solder material 50 contains impurities, the amount of impurities, and the change in the amount of impurities over time, based on the temperature characteristics and electromagnetic characteristics of the solder material 50. Can do.
When the type and amount of impurities detected by the impurity sensor 30 satisfy the specified conditions, the impurity removing apparatus 10 is operated to remove impurities contained in the solder material 50.
[0028]
[Impurity removal equipment]
An impurity treatment tank 16 is installed adjacent to the solder tank 20. The impurity treatment tank 16 has a rectangular parallelepiped shape that is relatively long in the vertical direction.
The impurity treatment tank 16 and the solder tank 20 are connected by a supply pipe 14 and a return pipe 12. Although not shown, the supply pipe 14 and the return pipe 12 are provided with a forced transfer mechanism such as a pump.
Inside the processing tank 16, a plurality of bar-shaped electric heaters 60 are arranged at regular intervals in the vertical direction. The heater 60 extends in a direction orthogonal to the paper surface of FIG. 1, and a plurality of heaters 60 are arranged in parallel. Although not shown in the figure, each heater 60 is supplied with electric power and connected to a control panel and a control computer for controlling energization, and heating of a plurality of heaters 60 is started. Completion and heating temperature can be controlled arbitrarily.
[0029]
A drain port 18 is disposed in the lower part of the processing tank 16, and the solder material 50 containing impurities 52 accumulated at the bottom of the processing tank 16 at a relatively high concentration can be discharged from the processing tank 16.
[Impurity removal treatment]
The solder material 50 having an increased impurity content in the solder tank 20 is transferred to the impurity treatment tank 16 through the supply pipe 14 in a heated and melted state. It is not necessary to send the entire amount of the solder material 50 in the solder tank 20 at a time, and an amount that can be processed at once in the processing tank 16 may be sent.
[0030]
If the solder material 50 accommodated in the treatment tank 16 is left as it is, it is cooled and solidified by heat radiation. It may be forcibly cooled by ventilation.
Thereafter, the uppermost heater 60 among the plurality of heaters 60 is energized, and only the solder material 50 around the heater 60 is locally heated and melted.
Next, energization of the uppermost heater 60 is stopped, and energization is performed on the next-stage heater 60 adjacent below to heat and melt the surrounding solder material 50. At this time, when the solder material 50 on the upper side cools and solidifies, the impurities are pushed out from the solid phase side to the lower liquid phase side due to a difference in melting point from the solder material 50 or the like. Specifically, impurities having a melting point lower than the melting point of the solder material 50 are expelled from the solid phase when the solder material 50 is solidified and move to the liquid phase. As a result, the solder material 50 solidified around the uppermost heater 60 is relatively free of impurities. Impurities are accumulated at a high concentration in the solder material 50 in a heated and melted state existing around the lower heater 60.
[0031]
Next, if the energization of the second stage heater 50 is stopped and the third stage heater 60 adjacent to the lower side is energized, the same action as before occurs, and the upper solidified solder material. Impurities migrate and accumulate from 50 to the solder material 50 in the heated and melted portion below.
Such a process is repeated. As indicated by broken line arrows in FIG. 1, the heating and melting position of the solder material 50 by the heater 60 moves from the upper side to the lower side, and accordingly, the impurities 52 contained in the solder material 50 are also lower from the upper side. It accumulates in the liquid phase part while moving to. Eventually, a portion where impurities 52 are accumulated at a high concentration is generated at the bottom of the treatment tank 16.
[0032]
If the solder material 50 having a high impurity concentration accumulated at the bottom is discharged from the drain port 18, the solder material 50 remaining in the processing tank 16 is in a state in which impurities are removed.
In addition, if the removal of impurities cannot be performed purely by moving the heating and melting position only once from the top to the bottom, the movement of the heating and melting position can be repeated. By repeating, the impurities 52 contained in the solder material 50 are sequentially shifted from the upper side to the lower side, and the high-concentration impurities 52 are accumulated at the bottom of the processing tank 16.
[0033]
In this way, the solder material 50 in the processing tank 16 after the impurities 52 are removed is heated and melted by energizing all of the plurality of heaters 60, and the solder tank 20 from the return pipe 12. Send back to.
In the solder tank 20, the impurity concentration in the entire solder material 50 is lowered by adding the solder material 50 sent back from the impurity treatment tank 16 from which the impurities 52 are removed.
If the solder material 50 in the solder tank 20 is sequentially sent to the impurity treatment tank 16, subjected to impurity treatment in the impurity treatment tank 16, and returned to the solder tank 20, the solder material 50 in the solder tank 20 is converted into impurities. The content of is reduced, and good soldering performance can be exhibited.
[0034]
If the impurity removal of the solder material 50 in the impurity treatment tank 16 is performed periodically or continuously during the operation of the flow type soldering apparatus, the solder material 50 in the solder tank 20 is always in a high quality state with few impurities 52. Can be maintained.
[Impurity removal device with cooling function]
The impurity removing apparatus 10 of the embodiment shown in FIG. 2 is incorporated in the same flow soldering apparatus as that of the above embodiment. Although not shown, the supply pipe 14 and the return pipe 12 are connected to the solder tank 20.
The impurity removing device 10 has a flat rectangular parallelepiped shape that extends long in the horizontal direction. A plurality of heaters 60 are arranged in parallel at intervals from one end side to the other end side of the flat impurity treatment tank 16. The heater 60 can control the start and stop of energization in the same manner as in the above embodiment.
[0035]
A water cooling jacket 70 is provided outside the processing tank 16. The water cooling jacket 70 efficiently cools the treatment tank 16 adjacent to the water cooling jacket 70 by passing water from an inlet 72 provided at one end to an outlet 74 at the other end.
The impurity removal operation is basically performed in the same manner as in the above embodiment. When the energization to the heater 60 and the energization stop are sequentially switched in the direction of the broken line arrow in the figure and the heating and melting position of the solder material 50 is moved, the impurities 52 contained in the solder material 50 are transferred to one end side of the treatment tank 16. Accumulated in.
At this time, by having the water cooling jacket 70, the solder material 50 in the portion where the energization of the heater 60 is stopped is quickly cooled and solidified. The migration of the impurities 52 from the solid phase to the liquid phase is performed quickly and efficiently.
[0036]
In the above embodiment, the impurities 52 cannot be discharged from the bottom of the treatment tank 16 through the drain port 18 as in the above embodiment. Therefore, if the solder material 50 in which the impurities 52 are accumulated at the end of the treatment tank 16 is heated and melted by the heater 60 to be in a fluid state and then sucked up by a hose or a pipe, the solder material 50 is discharged from the treatment tank 16. it can.
[External heating]
The embodiment shown in FIG. 3 heats the solder material 50 inside from the outside of the treatment tank 16 instead of disposing a heater inside the impurity treatment tank 16.
The processing tank 16 has a bottomed cylindrical shape extending in the vertical direction. A drain port 18 is provided at the bottom of the processing tank 16.
[0037]
On the outer periphery of the processing tank 16, a heater 62 having an annular band shape is attached so as to surround the periphery over a plurality of stages from the upper part to the lower part of the processing tank 16. The heaters 62 in each stage can be sequentially switched between start and stop of energization, as in the above embodiment.
The impurity removal process can be performed in the same manner as in the above embodiment. The heating and melting position of the solder material 50 heated and melted by the heater 62 sequentially moves from the upper side to the lower side through the side wall of the processing tank 16. Impurities 52 contained in the solder material 50 are accumulated in the bottom of the treatment tank 16. A portion of the solder material 50 containing the impurity 52 at a high concentration is discharged from the drain port 18.
[0038]
In the above embodiment, since there is no heater in the internal space of the processing tank 16, the internal volume of the processing tank 16 can be efficiently used for accommodating the solder material 50. Maintenance management of the heater 62 can be easily performed. However, the heater 60 disposed in the treatment tank 16 is advantageous in that the solder material 50 can be directly heated.
[0039]
【The invention's effect】
An impurity removal method according to the present invention detects the amount of impurities contained in a solder material in a solder tank of a flow type soldering apparatus, and removes the solder material containing impurities when the amount of impurities exceeds a specified value. From the solder material heated and melted by the first heater to the solder material heated and melted by the n-th heater. Can be accumulated. as a result, Solder material containing impurities transferred from one end side to the other end side of the treatment tank and melted by the nth heater Once discharged, the remaining solder material will be of high quality with few impurities, and the solder material remaining in the processing tank will be returned to the solder tank to perform the soldering operation in a series of high quality and high performance. Can do.
[0040]
As a result, it is possible to improve the quality or performance of the soldering work by the flow type soldering apparatus and improve the work efficiency, greatly improving the soldering performance and productivity in manufacturing various electronic parts and electronic devices. Can contribute.
[Brief description of the drawings]
FIG. 1 is an overall structural diagram of a flow type soldering apparatus representing an embodiment of the present invention.
FIG. 2 is a cross-sectional structure diagram of an impurity removal apparatus representing another embodiment.
FIG. 3 is a cross-sectional structure diagram of an impurity removal apparatus representing still another embodiment.
[Explanation of symbols]
10 Impurity removal equipment
12 Supply pipe
14 Return pipe
16 Impurity treatment tank
18 Drain port
20 Solder tank
30 Impurity sensor
50 Solder material
52 Impurities
60, 62 Heater
70 Water cooling jacket

Claims (1)

Detecting the amount of impurities contained in the solder material in the solder tank of the flow type soldering apparatus, and transferring the solder material containing impurities from the solder tank to the processing tank when the impurity amount exceeds a specified value ( a) and
For solder material that is melted by the heating of n heaters (n is an integer of 2 or more) arranged from one end side to the other end side of the treatment tank,
Energize the first heater to heat and melt the solder material,
Stopping the first heater and energizing the second heater to heat and melt the solder material,
Stop the second heater and energize the third heater to heat and melt the solder material,
Thereafter, stopping and energizing the heaters in the order of arrangement from one end side to the other end side of the treatment tank,
(B) stopping the (n-1) th heater and energizing the nth heater to heat and melt the solder material;
The solder which contains impurities transferred from one end side to the other end side of the processing tank by the step (b) and melted by the nth heater is removed from the processing tank and remains in the processing tank. A step (c) of heating and melting the solder material and returning it to the solder bath of the flow soldering apparatus.

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