JP2000340938A - Soldering method and soldering device - Google Patents

Abstract

(57) [Summary] To provide an electronic circuit by soldering an electronic component to a printed wiring board in a solder bath. It is required to further improve the mechanical connection strength of the soldered portion.
In addition, lead poisoning poses a problem for lead solder. However, when lead-free solder is used, there is a problem in that a lift-off phenomenon is likely to occur due to segregation of components and the like. SOLUTION: After a molten solder 4 is supplied to a printed wiring board 2 by a jet wave 8 and soldered, a cooling liquid jet wave 15 of a cooling liquid 11 is covered from a cooling wave nozzle body 13 before the solder is completely solidified. It was made to cool rapidly by contacting the soldering surface. The cooling liquid 11 is supplied to the liquid temperature control device 16.
To control to an appropriate temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for soldering a plate-like work to be soldered on which a large number of electronic components such as a printed wiring board are mounted.

[0002]

2. Description of the Related Art When an electronic circuit is formed by mounting electronic components on a printed wiring board, soldering is performed. That is, electrical connection and mechanical connection are performed by mounting an electronic component on a printed wiring board and soldering electrodes and lead wires of the electronic component to a circuit pattern of the printed wiring board.

[0003] By the way, it is known that rapid cooling of solder immediately after soldering increases its soldering strength, that is, mechanical connection strength. For example, a soldering apparatus disclosed in Japanese Utility Model Publication No. 45-21716 is configured to provide a cooling step after a soldering step in a jet-type solder bath. Accordingly, it is considered that a highly reliable printed wiring board can be manufactured. The cooling technique described in Japanese Utility Model Publication No. 45-21716 discloses a structure in which a fan is blown to a printed wiring board to cool it.

The same applies to a reflow soldering apparatus. For example, Japanese Patent Application Laid-Open No. 60-6270 discloses a configuration in which a cooling fan for cooling a printed wiring board on which reflow soldering has been performed is provided. ing.

[0005] On the other hand, in the soldering process, the solderable portion of the printed wiring board and the solder are prevented from being oxidized to improve the solderability, and the fluidity of the molten solder is improved to ensure the fine soldered portion. In order to realize the so-called micro soldering that solders to
There is a soldering technique for performing soldering in an inert gas atmosphere having a low oxygen concentration.

A soldering apparatus for performing soldering in an inert gas atmosphere having a low oxygen concentration is configured to supply an inert gas such as a nitrogen gas (N ₂ gas) into a chamber to form an atmosphere having a low oxygen concentration. And a soldering process is performed in the chamber.

In such a soldering apparatus, since the consumption of N ₂ gas is added as running cost, it is necessary that the consumption of N ₂ gas required to maintain the target oxygen concentration be small. . Therefore, a special cooling technique is used so that the atmosphere outside the chamber does not flow into the chamber.

For example, the reflow soldering technique disclosed in Japanese Patent Application Laid-Open No. Hei 4-262882 is a technique in which cold N ₂ gas supplied from a cylinder is blown onto a printed wiring board after soldering to perform cooling. It is. Also,
The technology disclosed in Japanese Patent Application Laid-Open No. Hei 7-202405 is designed to cool the atmosphere in the chamber and remove the flux fume by filtering to blow the cooled atmosphere to the printed wiring board after soldering so that cooling can be performed. It is a technology configured in.

Japanese Patent Application Laid-Open No. 10-98259 discloses a technique of spraying a cooling liquid onto a printed wiring board after soldering to cool the printed wiring board.

Further, what is common to these prior arts is that the arrangement of the cooling device for cooling the printed wiring board is remote from the solder bath and the reflow heating chamber, and the flow soldering requires the soldering of the printed wiring board. The point is that the time from when the part is separated from the molten solder to when the cooling is started is long, and the part to be soldered is cooled after solidification of the solder. Also, in reflow soldering, the solder in the soldered part is melted by heating means,
The point is that the time from the end of the heating to the start of the cooling is long, and the configuration is such that the solder in the soldered portion is solidified and then cooled.

By the way, in each of the conventional examples described above, in the flow soldering, it is necessary that at least 10 seconds or more have elapsed after the temperature of the molten solder in the soldered portion has started to decrease, ie, after the solidification has started. The cooling is not started, and the cooling is not started until at least 15 seconds have elapsed in the reflow soldering.

[0012]

In recent years, electronic devices having an electronic circuit formed on a printed wiring board have come to be used in all fields of daily life, and have a high level of reliability as infrastructure supporting life. Is required. Therefore, it is required to further improve the mechanical connection strength of soldering.

[0013] Further, lead mixed into the solder of discarded electronic equipment begins to melt, which poses a problem of contaminating the environment and the human body with lead poison, and lead-less solder has been used. ing. However, this lead-less solder has a problem that a lift-off phenomenon is easily generated in a soldered portion due to solidification and segregation of its components. The lift-off phenomenon is a defect in soldering that causes a partially embrittled region in the soldered part due to segregation of the solder in the soldered part and causes peeling or cracking in the soldered part. It is. In particular, it is known that it easily occurs in leadless solder containing bismuth.

In order to prevent such a lift-off phenomenon from occurring, the printed wiring board after soldering, that is, the solder at the portion to be soldered is rapidly cooled so that segregation does not occur. It is.

However, the conventional cooling technology that relies on air blowing has a problem in that since the cooling medium is a gas, the amount of heat for raising the temperature per unit volume of the cooling medium by a predetermined value is small, and the cooling rate cannot be increased. Also, in the technology of cooling by spraying a cooling liquid, there is also a problem that the cooling rate cannot be increased because the temperature of the cooling liquid sprayed and applied to the printed wiring board rises. Further, there is a problem that the controllability of the cooling amount is very poor in any of the cooling techniques.

Further, in these prior arts, since the solder in the soldered portion is cooled after it is solidified, the mechanical connection strength of the soldering is not significantly improved. For the same reason, segregation, which is a problem when using leadless solder, cannot be eliminated. Therefore, the occurrence of the lift-off phenomenon cannot be eliminated.

An object of the present invention is to provide a soldering method capable of rapidly cooling molten solder in a portion to be soldered before it is completely solidified, controlling the cooling amount easily, and using a flow soldering method. Established a soldering method that does not affect the temperature of the molten solder during soldering, and does not affect the temperature of the heated atmosphere during reflow soldering. An object of the present invention is to make it possible to manufacture a printed wiring board having excellent soldering strength and high reliability.

[0018]

According to the soldering method of the present invention, a printed wiring board after soldering, that is, a work to be soldered is subjected to a jet wave of a cooling liquid before the solder at a soldered portion is completely solidified. It is characterized in that it is configured so that it can be cooled rapidly by contacting the same.

(1) While carrying a plate-shaped work to be soldered, the surface to be soldered is brought into contact with a jet wave of molten solder to perform soldering, and then the surface to be soldered is cooled. This is a method of performing soldering in such a manner that cooling is performed by contact with a jet wave.

Liquids are superior in heat conductivity to gases such as air and N ₂ gas, and have an extremely large amount of heat for raising the unit volume by a predetermined temperature. That is, it can be cooled rapidly when it is brought into contact with a coolant. Therefore, by bringing the work to be soldered into contact with the jet wave in which the cooling liquid flows, the soldered portion of the work to be soldered can be rapidly cooled. Further, the amount of cooling can be adjusted by the temperature of the cooling liquid, and controllability of the amount of cooling is excellent.

Therefore, the soldering can be performed by the jet wave of the molten solder while the work to be soldered is sequentially and continuously conveyed, and the cooling can be performed sequentially and continuously by the jet wave of the cooling liquid. Become. In addition, since it is configured to perform cooling by the jet wave in which the cooling liquid flows,
Immediately before the molten solder in the soldered portion is completely solidified, it can be cooled immediately at the position immediately after the jet wave of the molten solder comes into contact with the work to be soldered and soldering is performed. . In addition, the amount of cooling can be adjusted by the temperature of the cooling liquid, and the controllability of the amount of cooling is excellent.

Since the jet of the cooling liquid does not affect the temperature of the jet of molten solder, the temperature of the molten solder does not change due to the jet of cooling liquid, and the soldering temperature does not change. Stable soldering can be continued.

Therefore, while the work to be soldered is carried by the carrying means, the surface to be soldered is brought into contact with the jet wave of the molten solder to supply the solder to the part to be soldered. The solder attached to the soldered part of the work can be cooled quickly and with the desired cooling amount, greatly increasing the mechanical connection strength of the solder attached to the soldered part of the work to be soldered. Will be able to do it. Further, occurrence of segregation can be prevented.

(2) Solder is supplied in advance to a portion to be soldered of a plate-like work to be soldered, and then the plate-like work to be soldered is heated while being transported and is supplied in advance. The solder is melted and soldered, and then the work to be soldered is brought into contact with a jet of cooling liquid to perform cooling.

Thus, the reflow soldering is performed while the work to be soldered is sequentially and continuously conveyed, and the cooling can be performed sequentially and continuously by the jet flow of the cooling liquid. Moreover, since the cooling is performed by the jet wave in which the cooling liquid flows, the cooling is rapidly performed at a position immediately after the reflow soldering before the molten solder in the soldered portion is completely solidified. It is possible to do. In addition, the amount of cooling can be adjusted by the temperature of the cooling liquid, and the controllability of the amount of cooling is excellent.

Also, since the jet of the cooling liquid does not affect the temperature of the heating atmosphere, the temperature of the heating atmosphere does not change due to the jet of the cooling liquid, and the soldering temperature does not change. You can continue to attach.

Accordingly, it is possible to rapidly cool the soldered portion of the reflow-soldered work to be soldered at a desired cooling amount, and the solder adhered to the soldered portion of the work to be soldered can be cooled. The mechanical connection strength of the solder can be greatly increased.

(3) In a soldering apparatus for performing soldering by bringing a plate-shaped work to be soldered into contact with molten solder while being conveyed by a conveying means, the plate-shaped work to be soldered comes into contact with the molten solder and separates. The soldering apparatus is provided with a cooling liquid tank for bringing the plate-shaped work to be soldered into contact with the jet flow of the cooling liquid at a position at the subsequent stage.

Thus, while the work to be soldered is sequentially and continuously conveyed, the molten solder is supplied to the soldered portion of the work to be soldered to perform the soldering, and the cooling is performed by the jet wave of the cooling liquid. The contact can be performed sequentially and continuously. Moreover, since the cooling is performed by the jet wave in which the cooling liquid is flowing, the molten solder in the portion to be soldered is located immediately after the molten solder comes into contact with the work to be soldered and soldering is performed. Cooling can be performed rapidly before it completely solidifies. In addition, the amount of cooling can be adjusted by the temperature of the cooling liquid, and the controllability of the amount of cooling is excellent.

Further, since the jet of the cooling liquid does not affect the temperature of the jet wave of the molten solder, the temperature of the molten solder may change due to the jet of the cooling liquid, and the soldering temperature may also change. Therefore, stable soldering can be continued.

Therefore, while the work to be soldered is carried by the carrying means, the surface to be soldered is brought into contact with the molten solder to supply the molten solder, and immediately thereafter, the work adheres to the soldered portion of the work to be soldered. This makes it possible to cool the solder quickly and with the desired amount of cooling, so that the mechanical connection strength of the solder attached to the soldered portion of the work to be soldered can be greatly increased.

(4) A plate-shaped work to be soldered, to which solder has been supplied in advance to the soldered portion, is heated by a heating means while being conveyed by a conveying means to melt the previously supplied solder. In the soldering apparatus for performing the soldering by using the soldering apparatus, the soldering apparatus is provided at a position subsequent to the heating means, with a cooling liquid tank for bringing the plate-shaped work to be soldered into contact with a jet of cooling liquid. Constitute.

Thus, the reflow soldering is performed while the work to be soldered is sequentially and continuously conveyed, and the cooling can be sequentially and continuously performed by bringing the work into contact with the jet wave of the cooling liquid. . Moreover, since the cooling is performed by the jet wave in which the cooling liquid flows, the cooling is rapidly performed at a position immediately after the reflow soldering before the molten solder in the soldered portion is completely solidified. It is possible to do. In addition, the amount of cooling can be adjusted by the temperature of the cooling liquid, and the controllability of the amount of cooling is excellent.

Also, since the jet of the cooling liquid does not affect the temperature of the heating atmosphere, the temperature of the heating atmosphere does not change due to the jet of the cooling liquid, and the soldering temperature does not change. You can continue to attach.

Therefore, the solder at the soldered portion of the reflow-soldered work to be soldered is rapidly reduced.
Moreover, it is possible to cool with the desired cooling amount,
The mechanical connection strength of the solder attached to the soldered portion of the work to be soldered can be greatly increased.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A soldering method and a soldering apparatus according to the present invention can be carried out in the following embodiments.

(1) First Embodiment A first embodiment of a soldering method according to the present invention will be described with reference to FIG.

FIG. 1 is a diagram showing a first basic principle for explaining Embodiment 1 of the soldering method of the present invention.

In the first embodiment, the lower surface 2a of the printed wiring board 2 conveyed in the direction of arrow A by the conveyor 1 is the surface to be soldered, and the surface to be soldered is There is a soldering part. Soldering is flow soldering. That is, the molten solder 4 which is heated by a heater (not shown) and is in a molten state is accommodated in the solder bath 3, and the molten solder 4 is supplied to the blowing port 7 of the nozzle body 6 by the pump 5 to form a jet wave 8. Then, the surface to be soldered of the printed wiring board 2 conveyed by the conveyor 1 in the direction of arrow A is brought into contact with the jet wave 8, and the molten solder 4 is supplied to the portion to be soldered to perform the soldering. Of course, the power of the heater is controlled by a temperature adjusting means (not shown), and the temperature of the molten solder 4 is maintained at a target temperature.

Then, the printed wiring board 2 is
The jet wave of the cooling liquid (cooling liquid jet wave) 15 is printed at a position immediately after the latter stage after being separated from the jet wave 8 of the printed wiring board 8 so as to contact the lower surface 2 a (the surface to be soldered) of the printed wiring board 2. The wiring board cooling device 9 is provided. It is preferable that the cooling liquid jet wave 15 be provided at a position within 5 seconds after the printed wiring board 2 is separated from the jet wave 8 of the molten solder 4 as much as possible. This is because the molten solder 4 supplied to the portion to be soldered of the printed wiring board 2 can be cooled rapidly before the molten solder 4 is completely solidified within this time.

That is, this makes it possible to greatly increase the mechanical connection strength of soldering more than ever, and also eliminates the occurrence of a lift-off phenomenon that tends to occur when using leadless solder. Become like

A cooling liquid nozzle body 13 is provided in the liquid tank 10 containing the cooling liquid 11, and the cooling liquid 11 stored in the liquid tank 10 is supplied to the cooling liquid nozzle body 13 by the pump 12 and is blown therefrom. It is configured to be jetted from the port 14 to form a coolant jet wave 15. Then, as described above, the cooling liquid jet wave 15 causes the printed wiring board 2 to
Is configured to be located immediately after separation from the jet wave 8.

The liquid temperature control device 16 is a device for maintaining the temperature of the cooling liquid 11 at a predetermined target temperature, and the cooling amount of the printed wiring board 2 can be adjusted by the set temperature. The liquid temperature control device 16 is mainly configured by a cooling device, and is configured to lower the temperature of the cooling liquid 11 whose temperature has increased by cooling the printed wiring board 2 after soldering.

The liquid tank 10 for the cooling liquid 11 is so small that it can be provided as close to the jet wave 8 as possible. Therefore, a pump 12 for jetting the cooling liquid 11 is provided outside the liquid tank 10. The cooling liquid 11 is circulated through a pipe 17.

As the cooling liquid 11, a liquid such as a fluorine-based inert liquid, water, an alcohol-based liquid, an oil-based liquid, a cleaning liquid-based liquid, or the like can be used. As examples of the fluorine-based inert liquid, Fluorinert (3M), Perfold (Tokuyama Soda) and the like are well known.
Due to its inactive properties, it has suitable properties as a cooling liquid.

The printed circuit board 2 is used as the cooling liquid 11.
When the cleaning liquid is used, the printed wiring board 2 can be cleaned together with the cooling of the solder in the soldered portion, so that a special action of two birds per stone can be obtained.

The soldering device thus configured is
Since the printed wiring board 2 conveyed by the conveyor 1 comes into contact with the jet wave 8 of the molten solder 4 and the molten solder is supplied to the portion to be soldered, and can be immediately brought into contact with the coolant jet wave 15 immediately thereafter. In addition, it is possible to rapidly cool the solder to be soldered before the solder is completely solidified, and the mechanical connection strength can be extremely increased. Further, even when a lead-less solder is used, segregation or the like can be eliminated by rapidly cooling the solder, and the mechanical connection strength can be extremely increased without causing a lift-off phenomenon.

Further, by adjusting the temperature of the cooling liquid 11, the amount of cooling can be easily adjusted, and desired optimal cooling can be performed.

Further, the cooling liquid jet wave 15 does not affect the temperature of the molten solder jet wave 8, and stable soldering can be performed.

(2) Second Embodiment A second embodiment of the soldering method of the present invention will be described with reference to FIG.

FIG. 2 is a view for explaining Embodiment 2 of the soldering method of the present invention, and is a view showing a second basic principle.

In the second embodiment, the cream solder 19 is applied to the lower surface 2a and the upper surface 2b of the printed wiring board 2 transported in the direction of arrow A by the transport conveyor 1, respectively.
And a case where the electronic component 18 is mounted. However, the cream solder 19 and the electronic component 18 may be mounted only on the lower surface 2a or only on the upper surface 2b. The portion to which the cream solder 19 is supplied in advance is the portion to be soldered. This soldering is reflow soldering.

That is, heating means 20 (for example, an infrared heating device, a hot air heating device, or a heating device using them in combination) are provided on the upper side and the lower side of the conveyor 1, respectively. The cream solder 19 previously supplied to the soldered portion of the printed wiring board 2 conveyed in the direction of arrow A at 1 is heated by the heating means 20 and melted, and soldering is performed. of course,
The heating power supplied to the heating means 20 is controlled by a temperature adjusting means (not shown) to maintain the target heating temperature.

Then, at a position immediately after the printed wiring board 2 is carried out from the heating means 20, the cooling liquid jet wave 15 of the cooling liquid 11 contacts the lower surface 2 a of the printed wiring board 2. Is provided with a printed wiring board cooling device 9. The position where the cooling liquid jet wave 15 is provided is preferably provided at a position within 7 seconds as much as possible after the start of carrying out the printed wiring board 2 from the heating means 20. This is because the reflow soldering does not interrupt the heating of the printed wiring board more rapidly than the flow soldering, and the soldered portion of the printed wiring board 2 is generally within this time (7 seconds). This is because it is possible to rapidly cool the melted solder 19 supplied to the solder before the solder is completely solidified.

That is, this makes it possible to greatly increase the mechanical connection strength of soldering more than ever, and also eliminates the occurrence of a lift-off phenomenon that tends to occur when using leadless solder. Become like

As in the first embodiment, the cooling liquid nozzle body 13 is provided in the liquid tank 10 for storing the cooling liquid 11.
The cooling liquid 11 accommodated in the liquid tank 10 is supplied to the cooling liquid nozzle body 13 by the pump 12 and jetted from the blowing port 14 to form a cooling liquid jet wave 15. is there. Further, the liquid temperature control device 16 controls the cooling liquid 1.
1 is a device for maintaining the temperature of the printed wiring board 2 at a predetermined target temperature, and the cooling amount of the printed wiring board 2 can be adjusted by the set temperature.

The liquid temperature control device 16 is mainly composed of a cooling device, and is configured to lower the temperature of the cooling liquid 11 whose temperature has increased by cooling the printed wiring board 2 after soldering.

The liquid tank 10 for the cooling liquid 11 is so small that it can be provided as close to the heating means 20 as possible. Therefore, a pump 12 for jetting the cooling liquid 11 is provided outside the liquid tank 10. The cooling liquid 11 is circulated through a pipe 17. The material suitable for the cooling liquid 11 and its function are the same as those of the first embodiment, and a detailed description thereof will be omitted.

The soldering apparatus thus configured is
The printed wiring board 2 conveyed by the conveyer 1 is heated by the heating means 20 to melt the cream solder 19 previously supplied to the portion to be soldered, and then immediately contact the coolant jet wave 15. Therefore, it is possible to rapidly cool the solder to be soldered before the solder is not completely solidified, and the mechanical connection strength can be extremely increased.

Even when lead-free solder is used, segregation and the like can be eliminated by rapidly cooling the solder, and the mechanical connection strength can be made extremely large without causing a lift-off phenomenon. Can be.

Further, by adjusting the temperature of the cooling liquid 11, the amount of cooling can be easily adjusted, and desired optimum cooling can be performed.

Further, the cooling liquid jet wave 15 does not affect the temperature of the heating atmosphere, so that stable soldering can be performed.

The portion to be soldered on the upper surface 2b of the printed wiring board 2 does not come into direct contact with the cooling liquid jet wave 15, but can be cooled rapidly through the printed wiring board 2. Also, the solder in the soldered portion on the upper surface 2b can be cooled in the same manner as the soldered portion on the lower surface 2a.

(3) Detailed Configuration Example of Printed Circuit Board Cooling Apparatus A printed circuit board cooling apparatus used in the soldering method of the present invention will be described with reference to FIG.

FIGS. 3A and 3B are views for explaining the configuration of the liquid tank portion of the cooling liquid in which the jet flow of the cooling liquid is formed. FIG. 3A is a perspective view showing the entire volume, and FIG. It is the figure seen from the II section.

That is, a pipe-shaped cooling liquid nozzle body 13 provided with a slit-shaped blowing port 14 is provided in an elongated liquid tank 10 having a cross section of about several cm square. A liquid supply joint 21 is provided, and the liquid tank 1
A cooling liquid recirculation joint 22 is provided on the tank bottom side 10a. Then, the coolant circulation pipe 17 is connected through the coolant reflux joint 22.

That is, when the coolant 11 is supplied from the coolant supply joint 21, the outlet 14 of the coolant nozzle 13 is
This is a mechanism in which the cooling liquid 11 is jetted from the liquid to form a cooling liquid jet wave 15.

On the other hand, the printed wiring board 2, whose both ends are held by the two parallel conveyors 1, is conveyed on the coolant jet wave 15 while being in contact with the coolant jet wave 15. The solder in the soldered portion of the printed wiring board 2 can be rapidly cooled.

Next, a printed wiring board cooling device will be described with reference to FIG. 4 and FIG.

FIG. 4 is a block diagram for explaining a configuration example of the printed wiring board cooling device.

This configuration example comprises a coolant circulation system and a coolant temperature control device.

That is, the coolant circulation system is provided with a storage tank 23 for temporarily storing the coolant 11 in addition to the liquid tank 10 for forming the coolant jet wave 15. The supply of the cooling liquid 11 and the reflux from the liquid tank 10 are performed through the storage tank 23.

As a result, the cooling liquid 11 evaporates or adheres to the printed wiring board 2 and is taken out, so that the cooling liquid 11 is removed.
Can be covered by the amount of the cooling liquid 11 stored in the storage tank 23 having a large capacity even if the total liquid amount of the cooling liquid 1 decreases, and the cooling liquid 1 in the liquid tank 10 forming the cooling liquid jet wave 15 can be covered.
The amount of 1 can be kept constant. Thereby, a stable coolant jet wave 15 can be formed.

That is, the cooling liquid 11 is supplied from the storage tank 23 of the cooling liquid 11 to the cooling liquid nozzle body 13 by the pump 12, forms a cooling liquid jet wave 15, flows into the liquid tank 10, and then flows into the storage tank 23. Reflux. The supply and reflux of the cooling liquid 11 are performed via a pipe 17.

Then, the cooling liquid temperature control device includes the pump 1
While the coolant 11 is being supplied from 2 to the coolant nozzle body 13, a cooling heat exchange unit 25 having a cooling coil 24 is provided;
A heating heat exchange unit 27 having a heater 26 is provided,
The cooling heat exchange unit 25 is driven to be cooled by a cooling unit 28 composed of a chiller or the like, and the heating heat exchange unit 27 is heated by a heating unit 29 composed of a heating power control circuit or the like.

Further, the cooling unit 28 and the heating unit 29
Is provided with a temperature control unit 30 for controlling the temperature. The temperature control unit 30 is constituted by a microcomputer system, instructing the operation unit 31 for inputting a target temperature T _T with predetermined
It has. Further, the blowing port 14 of the cooling liquid nozzle body 13
Is provided with a liquid temperature sensor 32 for detecting the temperature of the cooling liquid 11, and the temperature control unit 30 inputs the detected temperature T _C from its input port 30a and refers to the temperature.
8 and the heating unit 29 are connected to their output ports 30b, 30c.
Is controlled by the control signals S _C and S _H output from the controller to maintain the temperature of the coolant jet wave 15 at the target temperature T _T.

Since the temperature of the cooling liquid 11 rises by cooling the printed wiring board 2 having a high temperature, the heating heat exchanging section 27 and the heating section 29 are usually unnecessary. This is necessary when, for example, it is desired to quickly raise the temperature of the cooling liquid 11 to about 80 ° C., which is about the same as room temperature. Further, the cooling is performed by setting the temperature of the cooling liquid 11 to 80 ° C., but the type of the printed wiring board 2 to be soldered changes to 90 ° C.
In the event that a production situation such as cooling at a coolant temperature of 10 ° C. occurs, the heating heat exchange unit 2 is used to continue production without delay.
7 and the heating unit 29 are required.

Next, a procedure for controlling the temperature of the cooling liquid will be described with reference to FIG.

FIG. 5 is a flowchart for explaining a control procedure for controlling the temperature of the coolant.

Temperature control section 3 for controlling the temperature of cooling liquid 11
Since 0 is constituted by a microcomputer system, its control procedure can be realized on software.

That is, in step S1, the instruction operating section 31
Load the target temperature T _T, which is indicated, followed by the routine proceeds to step S2 reads the detected temperature Tc of the temperature sensor 32.

When the temperature deviation ΔT predetermined in step S3 is, for example, ΔT = 1 ° C., the liquid temperature T _C of the cooling liquid 11 is in the range of T _T −ΔT <T _C <T _T + ΔT. whether the determined, the process proceeds to step S4 when the temperature T _C of the cooling fluid 11 is within this range, the cooling instruction signal S
_C and the heating command signal S _H are turned off to perform neither cooling nor heating. However, in step S3, the temperature T
_{If C} is not within the above range, the process proceeds to step S5,
It is determined whether or not the temperature T _C of the coolant 11 has risen above the target temperature T _T by more than the deviation value ΔT, that is, whether T _C > T _T + ΔT, and the coolant 11 has exceeded this range.
The operation proceeds to step S6 to output a cooling command signal S _C if the temperature of is increasing. Incidentally, when the already heated command signal S _H when outputting the cooling instruction signal S _C is output, which it to OFF.

On the other hand, at step S5, the temperature T
_{If C} is determined not to be a _{T C>} T T + ΔT, that is, when it is determined that T _C <T _T -.DELTA.T outputs a heating command signal S _H and proceeds to step S7. Incidentally, when the already cooled command signal S _C when outputting a heating command signal S _H is output to it to OFF.

After performing the processing of steps S4, S6 and S7, the procedure returns to step S1 and repeats the same procedure.

Next, another configuration example of the printed wiring board cooling device will be described with reference to FIG.

FIG. 6 is a block diagram for explaining another configuration example of the printed wiring board cooling device.

That is, in this configuration example, only an air-cooled radiator is provided as a coolant temperature control device.

That is, the radiator 33 has a large number of heat radiating plates 33a, radiates heat by blowing air from the blowing fan 34, and cools the cooling liquid 11 flowing in the direction of the arrow. When it is not necessary to control the liquid temperature of the cooling liquid 11 very finely, such a configuration is sufficient and the radiator 33 is used.
If the design value of the heat radiation amount is set to a sufficiently large value, it is possible to maintain the temperature of the coolant 11 at a temperature equal to or lower than a predetermined temperature.

Although the radiator 33 is of an air-cooled type, a water-cooled type using underground water or the like can be used. In short, if the design value of the heat radiation amount is sufficiently large, the temperature of the coolant jet wave 15 can be maintained at a predetermined target temperature T _T or lower.

[0090] (4) The soldering method or embodiment of applying the device of the present invention with reference to N ₂ flow soldering apparatus embodiment Figure 7 in which the present invention is applied to the N ₂ flow soldering apparatus will be described .

FIG. 7 is a side sectional view of an N ₂ flow soldering apparatus to which the present invention is applied. This embodiment of the soldering apparatus is an embodiment in which the soldering technique of the present invention is applied to the technique of the soldering apparatus disclosed in JP-A-7-202405.

That is, a preheating heater 40 for preheating the printed wiring board 2 and a jet wave 8 of the molten solder 4 along the conveyor 1 for conveying the printed wiring board 2.
And a liquid bath 10 for forming a cooling liquid jet wave 15 of the printed wiring board cooling device 9 described with reference to FIGS. 3, 4 and 5.
Is provided at a position immediately after the position where the printed wiring board 2 separates from the jet wave 8 of the molten solder 4 and immediately thereafter.

The cooling liquid jet wave 15 is moved to a position where the printed wiring board 2 separates from the jet wave 8 of the molten solder 4 and is conveyed and arrived within 5 seconds as much as possible (for example, the printed wiring board 2).
The liquid tank 10 is formed so as to be formed at a position within 10 cm from the peel back point as much as possible when the transfer speed is 120 cm / min.

Thus, the molten solder 4 supplied to the portion to be soldered of the printed wiring board 2 can be rapidly cooled before it is completely solidified, and the mechanical connection strength is increased more than ever. be able to. Further, even when lead-free solder is used, occurrence of soldering failure such as a lift-off phenomenon can be prevented.

The soldering apparatus is provided with a chamber 41 along the conveyor 1 so as to cover the preheating heater 40 and the jet 8 of the molten solder 4 with the chamber 41. And molten solder 4
A gas blowing nozzle 42 is provided at a position in the vicinity of the jet wave 8 to supply the N ₂ gas 43 from the nozzle 42 into the chamber body 41, and the low oxygen concentration N ₂ gas ( It is configured to form an atmosphere of (inert gas).

Suppression plate 44 provided on chamber body 41
Is a plate-shaped member provided in a direction orthogonal to the transport direction of the transport conveyor 1, and by partitioning the inside of the tunnel-shaped chamber body 41 with the restraining plate 44, unnecessary atmosphere flow in the chamber body 41 is reduced. It is configured to suppress and form a stable low oxygen concentration N ₂ gas atmosphere. That is, a labyrinth flow path is formed in the tunnel-shaped chamber body 41 by the suppression plate 44.

Further, the gaseous flux fume generated in the chamber body 41 is cooled and atomized by the cooling unit 50 outside the chamber body 41, and the atomized flux is filtered by the filter 51 provided adjacently. A flux fume collecting device 45 for collecting and removing is provided. That is, the suction casing 46 is located above the jet wave 8 of the molten solder 4.
The flux fume sucked by the blower 48 through the suction port casing 46 and the pipe 47 serving as a connection pipe is guided to the collection device 45 to remove the flux, and the chamber body 41 is discharged from the discharge port casing 49. It is a mechanism that recirculates inside.

The printed wiring board 2 is usually coated with a flux before soldering.

The discharge port housing 49 is connected to the soldering surface side of the printed wiring board 2 conveyed by the conveyer 1 to the downstream side of the liquid tank 10 for forming the cooling liquid jet waves 15, that is, the lower side in FIG. An opening is provided toward the surface 2a of the printed wiring board 2, and the atmosphere cooled in the process of removing the flux fume is blown onto the surface of the printed wiring board 2 to be soldered, thereby also forming the surface 2a on the lower side. It is configured so that the solder in the soldering part can be cooled. In addition, this collection device 4
The cooling technique using the component 5 is disclosed in Japanese Unexamined Patent Publication No. 7-20240.
Although this technique is disclosed in Japanese Patent Application Laid-Open No. 5 (1999) -2005, if it is not necessary to use this cooling technique together, the direction and position of the discharge port housing 49 may be changed (for example, the molten solder
May be changed to return to the space above the jet wave 8).

Here, the cooling unit 50 of the collecting device 45 may be of an air cooling type, a liquid cooling type, or a cooling type using a chiller or the like. The flux using an alcohol-based solvent liquefies and atomizes when its temperature falls to about 70 ° C. or lower. However, since the flux is collected by the adjacent filter 51, the atmosphere containing the flux fume is heated to 70 ° C. Any structure that can be cooled below may be used. In the embodiment, a drain valve 52 is provided below the cooling unit 50.

In the soldering apparatus thus configured, when the printed wiring board 2 is carried in by the conveyor 1, the printed wiring board 2 is first preheated by the preheating heater 40. Subsequently, the lower surface 2a of the printed wiring board 2 comes into contact with the jet wave 8 of the molten solder 4,
The molten solder 4 is supplied to the portion to be soldered, and then, before the solder in the portion to be soldered is completely solidified, the molten solder 4 contacts the cooling liquid jet wave 15 and is rapidly cooled to a target temperature. The cooling is gradually performed by the cool atmosphere blown from the discharge port housing 49.

Therefore, the mechanical connection strength of the soldered portion of the printed wiring board 2 by the solder is greatly increased. Further, when lead-free solder is used, the occurrence of the lift-off phenomenon is prevented, and the printed wiring board 2 with high soldering reliability can be produced.

Further, the cooling liquid jet waves 15
Stable soldering can be performed without affecting the temperature of the jet wave 8.

The cooling liquid 11 has a boiling point of, for example, 215.
Use Fluorinert at 3 ° C. (3M). In this case, when the jet wave 8 of the molten solder 4 at about 250 ° C. is supplied to the portion to be soldered, the printed wiring board 2 and the coolant jet wave 1
A part of the florinate is vaporized when the fluorinate 5 contacts, and the vaporized florinate is cooled by the cooling unit 5 of the collection device 45.
0, it is possible to make the liquid droplets and collect them.
It is possible to discharge and collect through a zero drain valve 52. This can be separated by a significant difference in boiling point from the boiling point of the alcohol-based solvent.

[0105] (5) with reference to N ₂ reflow soldering apparatus embodiment 8 of the present invention is applied to a soldering method or embodiment example of applying the apparatus of the present invention to N ₂ reflow soldering apparatus explain.

FIG. 8 is a side sectional view of an N ₂ reflow soldering apparatus to which the present invention is applied. This embodiment of the soldering apparatus is also an embodiment in which the soldering technique of the present invention is applied to the technique of the soldering apparatus disclosed in JP-A-7-202405.

That is, the heating section heating chamber 54, the equalizing section heating chamber 55, the reflow section heating chamber 56, and the cooling section cooling chamber 57 are arranged along the conveyor 1 for transporting the printed wiring board 2.
Is provided by the chamber body 41, and the heating section heating chamber 54
A labyrinth part 58 provided with a restraining plate 44 is provided at the carry-in port of the cooling unit 57 and the carry-out port of the cooling unit cooling chamber 57.
It is configured so as to secure the sealing property.

In each of the heating chambers 54, 55 and 56, a heating means 60 (for example, an infrared heating device, a hot air heating device or a heating device using them in combination) is provided on the upper side and the lower side of the conveyor 1, respectively. The heating amount can be adjusted by a temperature control device (not shown), and the heating profile can be adjusted.
There are also soldering apparatuses in which the heating means 60 is provided only on the upper side, and soldering apparatuses in which the heating means 60 is provided only on the lower side.

Further, each of the heating chambers 54, 55, 56 has N ₂
A gas supply port 59 is provided, and an N ₂ gas 43 is supplied from the N ₂ gas supply port to supply a low oxygen concentration N ₂ gas atmosphere (inactive) in the chamber body 41, that is, in each of the heating chambers 54, 55, 56. (Gas atmosphere).

Then, the liquid tank 10 of the printed wiring board cooling device 9 described in detail with reference to FIGS.
That is, the liquid tank 10 for forming the cooling liquid jet wave 15 is provided on the outlet side of the reflow section heating chamber 56, that is, the heating means 60.
It is provided at the position immediately after the latter stage.

Then, the cooling liquid jet wave 15 is generated within a position within 7 seconds as much as possible after the start of carrying out the printed wiring board 2 from the heating means 60 (for example, when the conveying speed of the printed wiring board 2 is set to 80 cm / min). The liquid tank 10 is provided so as to be formed at a position within 9 cm of the heating means 60 as much as possible. That is, approximately within this time, it is possible to rapidly cool the molten solder 4 supplied to the portion to be soldered of the printed wiring board 2 before the molten solder 4 is completely solidified.

As a result, the molten solder 4 supplied to the portion to be soldered of the printed wiring board 2 can be rapidly cooled before it is completely solidified, and the mechanical connection strength is increased more than ever. be able to. Further, even when lead-free solder is used, occurrence of soldering failure such as a lift-off phenomenon can be prevented.

Further, the gaseous flux fume generated in the heating chamber 56 is cooled and atomized outside the chamber body 41, that is, outside the heating chamber 56, and the atomized flux is adjoined. A flux fume collecting device 45 for collecting and removing with a filter 51 provided is provided.

That is, the suction port case 46 is provided above the reflow section heating chamber 56 where the flux fume is generated, and the flux sucked by the blower 48 through the suction port case 46 and the pipe 47 which is a connecting pipe. The fumes are guided to the collection device 45 to remove the flux, and return to the cooling unit cooling chamber 57 from the discharge port housing 49. The cream solder 19 supplied to the printed wiring board 2 in advance contains a flux.

The discharge port housing 49 is provided toward the printed wiring board 2, and the atmosphere cooled in the process of removing the flux fume is blown to the soldered portion of the printed wiring board 2, and this is also used. The lower surface 2a and the upper surface 2b are configured to be able to cool the solder of the soldered portions. The cooling technique using this component is the technique disclosed in Japanese Patent Application Laid-Open No. 7-202405.

Here, the cooling unit 50 of the collection device 45 is
The cooling unit 50a and the second cooling unit 50b are provided separately, and this is due to the fact that the ambient temperature in the reflow unit heating chamber 56 is usually 250 ° C. or higher. That is, the first cooling unit 50a cools to about 100 ° C.
It is cooled to 70 ° C. or lower in the cooling section 50b.

The cooling section 50 of the collecting device 45 may be of an air cooling type, a liquid cooling type, or a cooling type using a chiller or the like. Then, in the same manner as in the embodiment (4), the cooling liquid 11 has a fluorinert (3M
When the printed wiring board 2 is used, the florinert vaporized in the process of cooling the printed wiring board 2 (the process in which the printed wiring board 2 comes into contact with the cooling liquid jet wave 15) is cooled at a stretch to about 100 ° C. in the first cooling section 50a. A mechanism in which a flux using an alcohol-based solvent having a boiling point of about 70 ° C. is cooled to about several tens of degrees Celsius in the second cooling unit 50b and atomized, and collected by a filter 51 adjacent thereto. It is. The fluorinated droplets are collected from the drain valve 52.

In the soldering apparatus thus constructed, when the printed wiring board 2 is carried in by the conveyor 1, first, the printed wiring board 2 is heated to about 150 ° C. The cream solder 19 supplied in advance to the attachment section is heated, and is equalized in the uniform temperature section heating chamber 55 so that the preheating temperatures of the respective soldered sections are uniform. Then, the solder paste is heated to a temperature of about 230 ° C.
9 melts.

Subsequently, when carrying out of the printed wiring board 2 is started from the heating means 60 of the reflow section heating chamber 56, the cooling liquid is jetted before the solder of the soldered portion of the printed wiring board 2 is completely solidified. It is rapidly cooled to a target temperature by contacting the wave 15 and then gradually cooled by a cool atmosphere blown from the discharge port casing 49 of the cooling unit cooling chamber 57.

Therefore, the bonding strength of the soldered portion of the printed wiring board 2 by the solder is greatly increased. Further, when lead-free solder is used, the occurrence of the lift-off phenomenon is prevented, and the printed wiring board 2 with high soldering reliability can be produced.

Further, the cooling liquid jet wave 15 does not affect the temperature of the heating atmosphere, so that stable soldering can be performed.

(6) Example of Temperature Profile With reference to FIG. 9, a description will be given of a temperature profile of a portion to be soldered when the present invention is applied to the above-described N ₂ flow soldering apparatus and N ₂ reflow soldering apparatus. .

FIG. 9 is a diagram showing an example of a temperature profile of a soldered portion of a printed wiring board at the time of soldering. FIG. 9A shows the case of the flow soldering apparatus of FIG.
(B) is an example of the case of the reflow soldering apparatus of FIG. And the temperature of the cooling liquid was set to 80 ° C., respectively.

In the case of the flow soldering apparatus shown in FIG. 9A, the portion to be soldered is about 100
Preheated to about 250 ° C., and then contacted with the jet wave 8 of the molten solder 4 to supply the molten solder 4 to about 250 ° C., and then cooled at a stretch to about 80 ° C. by the cooling liquid jet wave 15, And is gradually cooled by a cold atmosphere blown from the discharge port housing 49. The broken line in the figure is
It is a temperature profile in the case of the conventional flow soldering apparatus.

In the case of the reflow soldering apparatus shown in FIG. 9B, the portion to be soldered is preheated to about 150 ° C. in the heating section heating chamber 54 and the soaking section heating chamber 55, and then the reflow section is heated. The cream solder 19 is melted by heating to about 230 ° C. in the chamber 56. After that, the cooling liquid jet wave 15 is used to cool down to about 80 ° C. at once, and then gradually cooled in the cooling unit cooling chamber 57 by the cool atmosphere blown from the discharge port housing 49. Note that the broken line in the drawing is a temperature profile in the case of a conventional reflow soldering apparatus.

[0126]

As described above, according to the soldering method and the soldering apparatus of the present invention, in the case of the flow soldering method of the first aspect, the molten metal supplied to the soldered portion of the work to be soldered is provided. Before the solder is completely solidified, it can be rapidly cooled by the jet wave of the cooling liquid, and by adjusting the temperature of the cooling liquid, the cooling amount of the soldered part can be adjusted to a desired value. it can.

As a result, the soldering strength (mechanical connection strength) of the work to be soldered can be greatly increased. In addition, even when lead-free solder is used, a lift-off phenomenon does not occur, and a printed wiring board with high soldering reliability can be manufactured.

Also in the case of the reflow soldering method according to the second aspect, after the solder previously supplied to the portion to be soldered of the work to be soldered is melted, the jet of the cooling liquid is formed before the solder is completely solidified. The waves allow rapid cooling, and the amount of cooling of the soldered portion can be adjusted to a desired value by adjusting the temperature of the cooling liquid.

As a result, the soldering strength can be greatly increased. Further, even when lead-free solder is used, a lift-off phenomenon does not occur, and a printed wiring board with high soldering reliability can be manufactured.

[0130] In the case of the flow soldering apparatus of claim 3, since the jet wave of the cooling liquid having a larger heat capacity per unit volume than the gas is brought into contact with the portion to be soldered and cooled, the cooling liquid is cooled. Even if the liquid bath that forms the jet wave of the solder is configured to be small, it is possible to rapidly cool the portion to be soldered, so that the liquid bath of the cooling liquid, It becomes possible to arrange a jet wave and to cool rapidly before the solder of a to-be-soldered part completely solidifies. Further, by adjusting the temperature of the cooling liquid, the cooling amount of the soldered portion can be adjusted to a desired value.

As a result, the soldering strength can be greatly increased. In addition, even when lead-free solder is used, a lift-off phenomenon does not occur, and a printed wiring board with high soldering reliability can be manufactured.

Also in the case of the reflow soldering apparatus according to the fourth aspect, since the jet flow of the cooling liquid having a larger heat capacity per unit volume than the gas is brought into contact with the portion to be soldered and cooled, the cooling liquid is cooled. Even if the liquid bath that forms the jet wave is formed in a small size, the part to be soldered can be rapidly cooled even if the liquid bath is formed near the reflow heating device. Can be rapidly cooled before the solder in the soldered portion is completely solidified. Further, by adjusting the temperature of the cooling liquid, the cooling amount of the soldered portion can be adjusted to a desired value.

As a result, the soldering strength can be greatly increased. In addition, even when lead-free solder is used, a lift-off phenomenon does not occur, and a printed wiring board with high soldering reliability can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first basic principle for explaining a first embodiment of a soldering method of the present invention.

FIG. 2 is a diagram showing a second basic principle for describing Embodiment 2 of the soldering method of the present invention.

FIG. 3 is a diagram for explaining a configuration of a liquid tank that forms a cooling liquid jet wave of the printed wiring board cooling device.

FIG. 4 is a block diagram illustrating a configuration example of a printed wiring board cooling device.

FIG. 5 is a flowchart for explaining a cooling liquid temperature control procedure.

FIG. 6 is a block diagram illustrating another configuration example of the printed wiring board cooling device.

FIG. 7 is a side sectional view of an N ₂ flow soldering apparatus to which the present invention is applied.

FIG. 8 is a side sectional view of an N ₂ reflow soldering apparatus to which the present invention is applied.

FIG. 9 is a diagram illustrating an example of a temperature profile of a soldered portion of a printed wiring board during soldering.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conveyor 2 Printed wiring board 2a Lower surface 2b Upper surface 3 Solder tank 4 Molten solder 5 Pump 6 Nozzle body 7 Blow outlet 8 Jet wave 9 Printed wiring board cooling device 10 Liquid tank 10a Tank bottom 11 Coolant DESCRIPTION OF SYMBOLS 12 Pump 13 Coolant nozzle body 14 Spout 15 Coolant jet wave 16 Liquid temperature control device 17 Pipe 18 Electronic component 19 Cream solder 20 Heating means 21 Coolant supply joint 22 Coolant return joint 23 Storage tank 24 Cooling coil 25 Heat exchange unit for cooling 26 Heater 27 Heat exchange unit for heating 28 Cooling unit 29 Heating unit 30 Temperature control unit 30a Input port 31 Command operation unit 32 Temperature sensor 33 Radiator 34 Blow fan 40 Preheater 41 Chamber body 42 Gas blowing nozzle 43 N ₂ gas 44 Suppression plate 45 Collector 46 Suction port Case 47 Pipe 48 Blower 49 Discharge port case 50 Cooling section 51 Filter 52 Drain valve 54 Heating section heating chamber 55 Equalizing section heating chamber 56 Reflow section heating chamber 57 Cooling section cooling chamber 58 Labyrinth section 59 N ₂ gas supply port 60 Heating means

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B23K 31/02 310 B23K 31/02 310H // B23K 101: 42

Claims (4)

[Claims] 1. A method for soldering a plate-shaped work to be soldered by bringing the surface to be soldered into contact with a jet wave of molten solder while carrying a plate-shaped work to be soldered, and then jetting a coolant through the surface to be soldered. A soldering method characterized by cooling by contacting with a wave. 2. A method according to claim 1, wherein solder is previously supplied to a portion to be soldered of the plate-like work to be soldered, and then the plate-like work to be soldered is heated while being conveyed. A soldering method comprising: melting a solder to perform soldering; and subsequently cooling the workpiece by bringing the work to be soldered into contact with a jet of cooling liquid. 3. A soldering apparatus for performing soldering by bringing a plate-shaped work to be soldered into contact with molten solder while being conveyed by a conveying means, wherein the plate-shaped work to be soldered comes into contact with the molten solder and separates. A soldering apparatus, comprising: a cooling liquid tank for contacting the plate-like work to be soldered with a jet of cooling liquid at a subsequent position. 4. A plate-shaped work to be soldered, to which solder has been supplied in advance to the soldered portion, is heated by a heating means while being conveyed by a conveying means to melt the previously supplied solder. A soldering device, which is provided at a position subsequent to the heating means and which is provided with a cooling liquid tank for bringing the plate-shaped work to be soldered into contact with a jet of cooling liquid. apparatus.