JPH10322009A - Soldering equipment - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide a soldering device that prevents a connection failure due to looseness of parts caused by cooling air. A soldering apparatus for mounting an electronic component (11) on a circuit board (10) and soldering the circuit board (10) is provided with a cooling tank (16) for cooling the atmosphere with a refrigerant, and using a refrigerant gas in the cooling tank (16) to solder the circuit board (10). The reliability of the connection of the solder alloy between the electrode of the electronic component 11 and the circuit board 10 is improved by uniformly cooling the joint in the atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering apparatus, and more particularly to a soldering apparatus for soldering electrodes or leads of a component to connection lands of a circuit board by using molten solder.

[0002]

2. Description of the Related Art When an electronic circuit is manufactured, an electronic component is mounted at a predetermined position on a circuit board by a mounting machine, and a flux is applied to a surface of the circuit board to be soldered. Then, the circuit board on which the electronic components are mounted is gently passed over the preheater to preheat, and then the solder jet is brought into contact with the lower surface of the circuit board by a flow soldering device to connect the electrodes or leads of the electronic components to the circuit board. Solder to land.

[0003] After soldering, the circuit board is conveyed to a cooling zone, where the solder is solidified by cooling. That is, for example, 18
Cooling air was generated by a blower fan having a rotation speed of about 00 rpm, and such cooling air was directly applied to the solder joints or components, thereby cooling the molten solder, electronic components, or circuit boards. .

[0004]

If a strong wind hits the components, especially large components, before the solder for connecting the electrodes or leads of the electronic components to the connection lands on the circuit board is completely solidified, the cooling wind is increased. Parts may be loose due to If the solder is cooled below the melting point and solidified while the electrodes of the electronic component are displaced, bonding failure will occur at the interface between the electrode of the component and the solder alloy, which will prevent the normal operation of the circuit. Will be hindered. Further, the cooling by the cooling air generated by driving the cooling fan has a problem that the cooling of the surface of the circuit board is not uniform depending on the location.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is intended to prevent the occurrence of connection failure due to wobbling of components due to cooling air and to improve the reliability of connection at solder joints. It is an object of the present invention to provide a soldering device having a reduced thickness.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a soldering apparatus for soldering an electrode or a lead of a component to a connection land of a circuit board with molten solder, comprising a cooling tank for forming a cooling atmosphere with a refrigerant. The present invention relates to a soldering apparatus characterized in that a soldered circuit board is introduced into the cooling tank to cool the atmosphere.

[0007] Cooling near the melting point of the solder may be performed by cooling the atmosphere in the cooling bath. Further, the cooling of the atmosphere may be performed by a static refrigerant flow. Alternatively, a gas having a higher specific gravity than air may be used as the refrigerant.

[0008] A transporting means for transporting the circuit board from above to below in the cooling bath may be provided. Further, a pipe for circulating the cooling liquid may be arranged below the cooling tank.
Alternatively, a heater may be provided at an upper portion of the cooling tank outside the circuit board carrying entrance.

[0009]

FIG. 2 shows an entire configuration of a soldering apparatus according to an embodiment of the present invention. This soldering apparatus mounts an electronic component 11 on a circuit board 10 and mounts the same. This is for forming a predetermined electronic circuit. The electronic component 11 is mounted on the circuit board 10 by a mounting machine. The electronic component 11 is temporarily fixed by an engaging force between the lead and the insertion hole.

The soldering device used for soldering the electronic component 11 to the connection lands of the circuit board 10 includes a solder dipping device 15 and a cooling bath 16. The solder dipping device 15 is provided with a conveying means 19 obliquely in its longitudinal direction, and the conveying means 19 allows the
When moving the inside of the electronic component 1, the flux is applied to the surface of the circuit board 10 to be soldered, preheated, and then brought into contact with a solder jet in a dipping bath.
One electrode or lead is to be soldered. Then, a cooling bath 16 is arranged downstream of the solder dipping device 15 in order to cool and solidify the molten solder.

As shown in FIG. 1, the cooling tank 16 is provided with a substrate carry-in port 23 at a position substantially corresponding to the end of the conveying means 19 on the solder dipping device 15 side. A substrate outlet 24 is provided at a position on the opposite side. Further, a drive shaft 27 and a driven shaft 28 are arranged vertically in the cooling tank 16. A belt 29 is stretched between the drive shaft 27 and the driven shaft 28. A plurality of holding frames 30 for holding the circuit board 10 are provided on the belt 29. The cooling tank 16 is provided with a refrigerant supply unit 34, and the refrigerant from the refrigerant supply unit 34 is supplied to the lower side of the cooling tank 16 through the tube 35 and the refrigerant inlet 36.

The gas supplied from the refrigerant supply section 34 forms a cooling atmosphere inside the cooling tank 16, and the gas supplied from the refrigerant supply section 34 is a gas having a specific gravity greater than that of air. Due to the supply, as shown in FIG. 1, the temperature of the cooling tank 16 is lower on the lower side than on the upper side.

The circuit board 1 loaded from the board loading port 23
0 indicates that the cream solder is still completely melted.
Such a circuit board 10 is transferred onto a holding frame 30 provided on a belt 29. The belt 29 causes the holding frame 30 to move the circuit board 10 downward as shown in FIGS.
As a result, the ambient temperature of the circuit board 10 decreases. Then, the molten solder on the circuit board 10 is melted and solidified, and the electrodes or leads of the electronic component 11 are securely soldered. And further belt 29
Is driven, the holding frame 3 is moved as shown in FIG.
0 moves upward again while holding the circuit board 10,
The circuit board 10 in which the solder is cooled and solidified and the electrodes or leads of the electronic component 11 are completely soldered to the connection lands
Is carried out from the substrate outlet 24.

As described above, the cooling tank 16 of the soldering apparatus according to the present embodiment is configured such that the holding frame 30 is attached to the belt 29, and the cooling tank 16 is driven by the drive shaft 27.
The belt 29 is intermittently rotated in the inside. The cooling tank 16 has a tube 3 from the refrigerant supply unit 34.
5 and the refrigerant gas inlet 36, refrigerant gas is introduced. As the refrigerant gas, a gas having a specific gravity larger than air having a specific gravity of 1, for example, carbon dioxide having a specific gravity of 1.52, carbon tetrachloride having a specific gravity of 1.63, or the like is used. Although the refrigerant gas stays in the lower part of the cooling tank 16 as shown in FIG. 1, the inflow amount is adjusted so that the temperature in the cooling tank 16 is kept low.

The circuit board 10 that has been soldered by the solder dipping device 15 is introduced into the cooling tank 16 from the board carry-in port 23 of the cooling tank 16 and placed on the holding frame 30. Next, the holding frame 30 is lowered downward as shown in FIG. 3, and the circuit board 10 placed on the holding frame 30 is cooled by the atmosphere of the refrigerant gas staying in the lower part in the cooling tank 16. The molten solder is solidified by cooling, and the electronic component 11 is soldered to the connection lands of the circuit board 10 and joined. After that, the holding frame 30 further moves up as shown in FIG. 4, and conveys the circuit board 10 to the position of the board outlet 24. Then, the circuit board 10 is carried out of the cooling tank 16 from the board carry-out port 24, and the cooling is completed.

A feature of such a soldering apparatus is that when the electronic component 11 is mounted on the circuit board 10, the entire circuit board 10 immediately after soldering is collectively cooled in the cooling tank 16 in an atmosphere. In this case, the molten solder alloy is rapidly solidified. Here, especially the cooling tank 16
The cooling near the melting point of the solder is performed by the static flow of the gaseous refrigerant in the inside, thereby preventing the electronic components 11 mounted on the circuit board 10 from wobbling due to the cooling wind and increasing the reliability of the connection of the solder joint. I try to make it.

By using a gaseous refrigerant having a specific gravity greater than that of air in the cooling tank 16, even if external air at a room temperature or higher enters the cooling tank, stable cooling of the circuit board 10 can be achieved at the lower portion of the cooling tank. doing. In addition, by controlling the temperature of the refrigerant, an optimal cooling rate is realized that is in accordance with the heat capacity caused by the size of the circuit board 10 and the number of the electronic components 11.

As electronic devices have become more multifunctional, component mounting has been more and more densely packed. Further, as seen in the enforcement of the PL law, the demand for safety and reliability of electronic devices has been higher.

According to the soldering apparatus according to the present embodiment, the electronic component 11 is cooled by the cooling air before the solder is solidified, particularly by cooling the vicinity of the melting point of the solder in the cooling bath 16 in a gas refrigerant atmosphere. Wobbling can be prevented, and the connection reliability of the solder joint is improved. Further, by performing cooling in the cooling tank 16 in the gas refrigerant atmosphere, the entire circuit board 10 can be cooled evenly.

By using a gaseous refrigerant having a specific gravity greater than that of air as the refrigerant in the cooling tank 16, even if outside air at a room temperature or higher is introduced into the cooling tank,
6, stable cooling of the circuit board 10 can be realized. In addition, by controlling the cooling temperature, it becomes possible to realize an optimum cooling rate according to the heat capacity caused by the size of the circuit board 10, the number of the electronic components 11, and the like.

FIG. 5 shows a cooling tank according to another embodiment. The cooling tank has a cooling liquid circulation pipe 40 arranged on the outer surface at the bottom. Such a cooling liquid circulation pipe 40 makes it possible to cool the lower part of the cooling tank 16 in particular. That is, when the cooling liquid is circulated through the cooling liquid circulation pipe 40 to cool the lower part of the cooling tank 16, the cooling efficiency is improved. Coolant circulation pipe 4
0 may be arranged inside the cooling bath 16 and along the surface of the bottom.

In the embodiment shown in FIG. 6, a heater 42 is provided outside the substrate carrying-in port 23 of the cooling bath 16 and at the upper portion thereof. By mounting the heater 42 on the upper outside of the substrate carrying-in port 23, the solder alloy can be maintained in a molten state until immediately before the soldering is carried into the cooling bath 16.

FIG. 7 shows an embodiment in which a coolant circulation pipe 40 for cooling the bottom of the cooling tank 16 and a heater 42 are provided.
And the supply of the refrigerant from the refrigerant supply unit 34 is controlled by the control valve 44, and the amount of the coolant circulating in the coolant circulation pipe 40 is controlled by the control valve 45. is there. These control valves 44 and 45 are controlled by a controller 46.

The controller 46 further includes the heater 42
Is also controlled. Note that the controller 46 is connected to a temperature sensor 47 that detects the temperature in the cooling bath 16, and with the detection of the temperature sensor 47,
By controlling the control valves 44 and 45 and the heater 42, the temperature in the cooling bath 16 can be controlled more reliably.

As another embodiment, in the cooling bath 16, only cooling near the melting point of the solder alloy, which is the most important temperature at the time of solidification of the molten solder alloy, is performed. After the circuit board 10 is carried out from the board carry-out port 24, the circuit board 10 may be cooled in the air or by another cooling device.

Although the cooling bath 16 of the above embodiment is arranged after the solder dipping device 15, the cooling bath 16 may be provided after the reflow furnace instead of such a configuration. You may.

In this case, cream solder is applied on the circuit board by, for example, a screen printing method. And after that, while mounting the electronic components at a predetermined position on the circuit board by the mounting machine, the circuit board with the electronic components mounted is gently introduced into the reflow furnace,
By melting the solder in the cream solder, the electrodes or leads of the electronic component are soldered to the connection lands of the circuit board. The cooling tank 16 is connected to a stage subsequent to such a reflow furnace, where cooling is performed.

[0028]

As described above, the present invention is provided with a cooling tank for forming a cooling atmosphere by a refrigerant, and introduces a soldered circuit board into the cooling tank to cool the atmosphere. .

Therefore, it is not necessary to perform cooling by the cooling air, so that displacement and movement of components due to the cooling air are prevented, and poor connection is avoided.

According to the structure in which the cooling in the vicinity of the melting point of the solder is performed by cooling the atmosphere in the cooling bath, the cooling bath near the melting point of the alloy, which is the most important temperature, can be more reliably achieved by the cooling bath. Will be possible.

According to the structure in which the cooling of the atmosphere is performed by the static flow of the refrigerant, the wobbling of the parts caused by the cooling air during the cooling of the atmosphere is reliably eliminated.

According to the configuration in which a gas having a specific gravity greater than that of air is used as the refrigerant, even if air at room temperature is mixed in from the outside, stable cooling of the circuit board is ensured particularly in the lower portion of the cooling tank. Done.

According to the structure in which the transfer means for transferring the circuit board from the upper part to the lower part in the cooling tank is provided, when the circuit board is transferred from the upper part to the lower part in the cooling tank, the solder is solidified by cooling. Is performed.

According to the structure in which the pipes for circulating the cooling liquid are arranged at the lower part of the cooling tank, it is possible to enhance the cooling effect of the cooling tank, especially at the bottom side.

According to the configuration in which the heater is provided in the upper part of the cooling tank outside the circuit board carry-in port, the solder can be maintained in a molten state until immediately before the solder is introduced into the cooling tank.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the internal structure of a cooling tank.

FIG. 2 is a longitudinal sectional view showing the overall configuration of the soldering apparatus.

FIG. 3 is a longitudinal sectional view of the soldering apparatus when cooling is performed in a cooling tank.

FIG. 4 is a longitudinal sectional view of the soldering apparatus showing a state in which a circuit board is carried out of a cooling bath.

FIG. 5 is a longitudinal sectional view of a cooling tank according to another embodiment.

FIG. 6 is a longitudinal sectional view of a cooling tank according to still another embodiment.

FIG. 7 is a longitudinal sectional view of a cooling tank according to still another embodiment.

[Explanation of symbols]

10 ‥‥ circuit board, 11 ‥‥ electronic components, 15 ‥‥ solder dipping device, 16 ‥‥ cooling tank, 19 ‥‥ transport means, 2
3 substrate inlet, 24 substrate outlet, 27 drive shaft, 28 driven shaft, 29 belt, 30 holding frame, 34 coolant supply unit, 35 tube, 36
{Coolant inlet, 40} Coolant circulation pipe, 42}
Heater, 44, 45 ‥‥ control valve, 46 ‥‥
Controller, 47 ° temperature sensor

Claims (7)

[Claims] 1. A soldering apparatus for soldering an electrode or a lead of a component to a connection land of a circuit board with molten solder, comprising: a cooling tank for forming a cooling atmosphere with a refrigerant; Is introduced into the cooling tank to cool the atmosphere. 2. The soldering apparatus according to claim 1, wherein cooling near the melting point of the solder is performed by cooling the atmosphere in the cooling tank. 3. The soldering apparatus according to claim 1, wherein the cooling of the atmosphere is performed by a static flow of a refrigerant. 4. The soldering apparatus according to claim 1, wherein a gas having a specific gravity larger than that of air is used as the refrigerant. 5. The soldering apparatus according to claim 1, further comprising a transfer means for transferring the circuit board from the upper part to the lower part in the cooling bath. 6. The soldering apparatus according to claim 1, wherein pipes for circulating a cooling liquid are arranged below the cooling tank. 7. The soldering apparatus according to claim 1, wherein a heater is provided on an upper portion of the cooling tank outside a circuit board carrying entrance.