JPH0550219A - Reflow soldering device - Google Patents

Abstract

PURPOSE:To offer the reflow soldering device which does not cause a sudden rise of soldering cost, and also, whose coolability to an object to be treated is satisfactory. CONSTITUTION:An object to treated, formed by placing electronic parts on a circuit board P to which solder is applied is heated and cooled, while carrying it by a conveyor 12 in a reflow chamber R2 and a cooling chamber R3 which are adjacent to each other and roughly closed up and the solder is melted and solidified, and the electronic parts are soldered to the circuit board P. A heat transmission means, for instance, a heat pipe 8 is provided extending over the inside and the outside of the cooling chamber R3. Also, in the cooling chamber, a once-through fan 7 for blowing inert, gas cooled by the heat transmission means, for instance, nitrogen gas to the circuit board P is provided. Since the inert gas is cooled enough in the cooling chamber, the reflow chamber R2 and the cooling chamber R3 can be formed to a closed space, and consumption of inert gas is obviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies a hot gas to an object to be processed, in which electronic parts are placed on a circuit board coated with solder, while successively advancing in a reflow chamber and a cooling chamber adjacent to each other. The present invention relates to a reflow soldering apparatus that melts a liquid and further solidifies the solder by blowing a cooling gas, and solders the electronic component to the circuit board, and in particular, a reflow solder that enhances the cooling efficiency of an object to be processed in a cooling chamber. The present invention relates to an attachment device.

[0002]

2. Description of the Related Art Conventionally, an immersion method or a jet method has been used for soldering an electronic component to a circuit board. In recent years, mounting boards have been highly densified or surface mounted, and the reflow method has been widely used for soldering from the viewpoint of reliability and productivity. As a typical reflow method, there is a nitrogen reflow method in which an inert nitrogen gas is heated and blown onto an object to be processed to melt the solder. In this nitrogen reflow method, theoretically, the metal surface of the object to be treated is not oxidized during soldering, so that it is not necessary to use a flux to which an antioxidant is added. Therefore, the post-cleaning step for removing the stains due to the antioxidant that scatters and adheres on the object to be processed during soldering, which is necessary when using the flux to which the antioxidant is added, is not required. In some cases, an inert argon gas is used instead of the nitrogen gas. As a technique related to this type of technique, for example, Japanese Patent Laid-Open No. 64-71571 is known.

[0003]

There is an open type soldering device by the nitrogen reflow method.
This is a state in which the preheating chamber, the reflow chamber, and the cooling chamber in which the objects to be processed are sequentially conveyed are in communication with the atmosphere.
In order to carry out soldering without oxidizing the metal surface of the object to be processed, it is necessary to maintain the soldering atmosphere at a nitrogen gas concentration close to 100%, and nitrogen gas escapes from the opening. A large amount of nitrogen gas must be continuously supplied to each chamber, which consumes a large amount of nitrogen gas and increases the soldering cost. Further, oxygen gas in the atmosphere may enter the cooling chamber, and it is difficult to completely oxidize the metal surface of the object to be processed.

There is a closed type nitrogen reflow soldering device to solve such a drawback. In this type, since the preheating chamber, the reflow chamber, the cooling chamber, and the like are almost sealed, heat tends to be accumulated, and there is a drawback that the object to be processed cannot be cooled sufficiently.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and its object is reflow soldering which does not cause a rise in soldering cost and which has a good cooling property of an object to be processed. To provide a device.

[0006]

In order to achieve the above object, the reflow soldering apparatus according to the present invention has a structure in which an object to be processed having electronic parts placed on a circuit board coated with solder is In a reflow soldering device that heats and cools while melting and solidifying the solder while transporting the adjacent and substantially sealed reflow chamber and cooling chamber, and inside the cooling chamber, the electronic component is soldered to the circuit board. The heat transfer means is provided from the outside to the outside. More specifically, a cross-flow blower for blowing the gas cooled by the heat transfer means to the object to be processed is provided in the cooling chamber, and the heat transfer means in the cooling chamber is provided so as to form a space between the suction port of the cross-flow fan. It is a thing.

[0007]

The function of the above technical means is as follows. Since the heat transfer means performs heat exchange between the inside of the cooling chamber and the outside, the atmosphere inside the cooling chamber is cooled. As a result, the workpiece to be transported is cooled in the cooling chamber. It is not necessary to introduce a cooled gas from the outside as an atmosphere in the cooling chamber. Therefore, the reflow chamber and the cooling chamber can be almost closed, and the space can be filled with an inert gas without causing oxidation. Soldering can be done. It is not necessary to use a flux containing an antioxidant as the solder. Therefore, the post-cleaning step for removing the dirt scattered on the object to be processed is not required. Since it is not necessary to introduce a large amount of gas from the outside, the soldering cost does not increase.

Further, since the space is formed between the heat transfer means in the cooling chamber and the suction port of the cross-flow fan, the gas suction of the cross-flow fan is performed well, and the cooled gas from the discharge port is treated. It can be sprayed onto the object, and the object to be processed can be cooled efficiently.

[0009]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9. [Embodiment 1] FIG. 1 is a schematic longitudinal sectional view of a reflow soldering apparatus according to an embodiment of the present invention. The nitrogen reflow soldering apparatus 100 shown in FIG.
Temperature rising preheater 2, preheating cross-flow fan 3, soaking preheat heater 4, reflow heater 5, reflow cross-flow fan 6, cooling cross-flow fan 7, heat pipe 8, carry-out side seal 9
Are sequentially arranged on the gantry 10 and are surrounded by the hood 11. A chain conveyor 12 is wound from the carry-in side seal 1 to the carry-out side seal 9. The conveyor 12 moves in the direction indicated by the broken line arrow and conveys the circuit board P from left to right in the figure.

The circuit board P is formed by applying solder and electronic parts placed thereon. The circuit board P is filled in the hood 11 while being conveyed by the conveyor 12, and the temperature raising preheating heater 2, the temperature preheating heater 4, The solder is melted by the nitrogen gas heated by the reflow heater 5, the solder is cooled and solidified by the nitrogen gas cooled by the heat pipe 8, and the electronic component is soldered to the circuit board P. Reference numeral 14 is a controller that controls the drive of the conveyor 12, each heater, and each cross-flow fan. The carry-in side seal 1 and the carry-out side seal 9 prevent the nitrogen gas filling the hood 11 from leaking to the atmosphere. In addition, solid line arrows in the figure indicate a uniform temperature preheating chamber R1, a reflow chamber R2, and a cooling chamber R3.
3 shows a circulation path of nitrogen gas through each cross-flow fan in FIG.

FIG. 2 is an enlarged view of the cooling chamber R3 shown in FIG. 1, and FIG. 3 is a transverse sectional view taken along the line AA of FIG. In both figures, S is a space formed between the cross-flow fan 7 and the heat pipe 8, and 7a is the cross-flow fan 7
Suction port, 7b is a rotary blade, 7c is a motor for rotating the blade 7b, 7d is a flow path guide, 7e is an outlet, 8a is a container of the heat pipe 8, and is arranged in the conveying direction of the conveyor 12. ing. Reference numeral 8b is a radiation fin provided on the container 8a.

By rotating the blade 7b by the motor 7c,
Nitrogen gas circulates along the route indicated by the solid arrow, and at this time, the nitrogen gas contacts the heat radiation fins 8b. Heat pipe 8
The cold atmosphere outside the hood 11 and the hot nitrogen gas inside the hood 11 are heat-exchanged with the working liquid inside the container 8a to cool the nitrogen gas. The cooled nitrogen gas is blown out from the blowout port 7e of the cross-flow fan 7 to cool the circuit board P on the conveyor 12.

There is a space S between the cross-flow fan 7 and the heat pipe 8, the fluid resistance on the suction port 7a side of the cross-flow fan 7 is low, and the nitrogen gas suction performance is not impaired. Also,
Since the radiating fins 8b are provided along the flow of nitrogen gas, the flow of nitrogen gas is rectified in the width direction of the conveyor 12, and uniform heat exchange is obtained. Further, the flow path guide 7d widens the nitrogen gas flow path from the blowout port 7e in the carrying direction of the conveyor 12 as shown in the drawing, and the circuit board P
In addition to increasing the area of contact of nitrogen gas with the heat radiation fins, it is easy to form a circulation path of nitrogen gas to the radiation fins 8b. Due to the existence of the upstream and downstream seals 1 and 9, the nitrogen gas hardly flows out to the outside air, so that the supply of the nitrogen gas is small and the soldering cost does not increase.

Second Embodiment Next, FIG. 4 is an enlarged view of a second embodiment of the cooling chamber R3 shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same parts as those in the previous embodiment. In the embodiment shown in FIG. 4, two types of heat pipes 8 are used.
A and 8B are provided. The heat pipe 8A has a plurality of containers 8a arranged in a direction perpendicular to the conveyor 12, and the heat pipe 8B has a plurality of containers 8a arranged in parallel with the conveyor 12. The radiating fins 8b of the heat pipe 8A are increased in size, the heat exchange efficiency is increased, and the heat pipe 8B is closer to the circuit board P. Therefore, the atmosphere is cooled correspondingly, and the cooling efficiency of the circuit board P is increased. Either one of the two types of heat pipes 8A and 8B in FIG. 4 may be omitted.

Third Embodiment Next, FIG. 5 is an enlarged view of a third embodiment of the cooling chamber R3 shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same parts as those in the previous embodiment. In the embodiment shown in FIG. 5, the cross-flow fan 7 is located on the downstream side of the conveyor 12, and nitrogen gas is used as the cross-flow fan 7.
Since it is sucked in, the amount flowing to the seal 9 side is reduced, and leakage of nitrogen gas to the outside is prevented. Further, the nitrogen gas cooled by the heat pipe 8 is immediately in contact with the circuit board P, so that the cooling efficiency is increased.

[Fourth Embodiment] FIG. 6 is an enlarged view of a fourth embodiment of the cooling chamber R3 shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same parts as those in the previous embodiment. In the embodiment shown in FIG. 6, the cross-flow fan 7 is located on the downstream side of the conveyor 12, and the circuit board P is cooled by the nitrogen gas blown from the cross-flow fan 7 on the downstream side. The circuit board P has been cooled to some degree by the time it reaches below the cross-flow fan 7, and reaches the bottom of the cross-flow fan 7 and is rapidly cooled. Further, by blowing the nitrogen gas from the cross-flow fan 7 toward the upstream side of the conveyor 12, the amount of the nitrogen gas flowing to the seal 9 side is reduced, and the leakage of nitrogen gas to the outside can be prevented.

[Embodiment 5] Next, FIG. 7 is an enlarged view of a fifth embodiment of the cooling chamber R3 shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same parts as those in the previous embodiment. In the embodiment shown in FIG. 7, the radiating fins 8c of the heat pipe 8 in the cooling chamber R3 are arranged in the width direction of the conveyor 12 in a multilayer shape along the circulation path of the nitrogen gas indicated by the solid arrow. Therefore, the contact area between the radiation fins 8c and the circulating nitrogen gas is wide, and the nitrogen gas is cooled well. Moreover, the rectification of the circulating nitrogen gas is also favorably performed by the radiation fins 8c.

[Sixth Embodiment] FIG. 8 is an enlarged view of a sixth embodiment of the cooling chamber R3 shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same parts as those in the previous embodiment. In the embodiment shown in FIG. 8, the hood 11 of the cooling chamber R3
Further, a plurality of plate-shaped heat pipes 8D are arranged inside and outside the hood 11. The plate shape serves as the container 8a and the heat radiation fin 8b of the heat pipe 8 in each of the above-described embodiments, which simplifies the configuration.

[Embodiment 7] Next, FIG. 9 is an enlarged view of a seventh embodiment of the cooling chamber R3 shown in FIG. In the figure, the same reference numerals as those in FIG. 2 indicate the same parts as those in the previous embodiment. In the embodiment shown in FIG. 9, the flow path guide 7d and the heat pipe 8 are integrated. The container 8a of the heat pipe 8 is arranged in the width direction of the conveyor 12 on the back side of the flow path guide 7d with respect to the circulation path of the nitrogen gas. The container 8a does not obstruct the circulation path of the nitrogen gas, and the heat radiation fins 8b of the heat pipe 8 effectively rectify the nitrogen gas and efficiently cool the circuit board P.

In each of the above embodiments, the cooling chamber R3 is provided above the conveyor 12, but the cooling chamber R3 may be provided below the conveyor 12 or both above and below. When the cooling chambers R3 are provided on both the upper and lower sides, it is not necessary to make the combination of the cross-flow fan 7 and the heat pipe 8 having the configurations shown in the above-described embodiments symmetrical with each other, but with the conveyor 12 as the center and with different points. The components shown in the drawings, for example, those shown in FIG. 4 and those shown in FIG. 6 may be arranged above and below the conveyor 12.

[0021]

As described in detail above, according to the present invention, it is possible to provide a reflow soldering apparatus which does not cause a rise in soldering cost and which has a good cooling property of the object to be processed.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a reflow soldering apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a cooling chamber R3 shown in FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is an enlarged view of a second embodiment of the cooling chamber R3 shown in FIG.

5 is an enlarged view of a third embodiment of the cooling chamber R3 shown in FIG.

6 is an enlarged view of a fourth embodiment of the cooling chamber R3 shown in FIG.

FIG. 7 is an enlarged view of a fifth embodiment of the cooling chamber R3 shown in FIG.

FIG. 8 is an enlarged view of a sixth embodiment of the cooling chamber R3 shown in FIG.

9 is an enlarged view of a seventh embodiment of the cooling chamber R3 shown in FIG.

[Explanation of symbols]

 100 Reflow soldering equipment 1 Carrying-in side seal 2 Temperature rising preheater heater 3 Preheating through-flow fan 4 Uniform temperature preheating heater 5 Reflow heater 6 Reflowing throughflow fan 7 Cooling throughflow fan 8, 8A, 8B, 8D Heat pipe 9 Outgoing side seal 10 stand 11 hood 12 chain conveyor 14 controller P circuit board R1 uniform temperature preheating room R2 reflow room R3 cooling room S space

Claims (3)

[Claims] 1. A solder is applied to a circuit board on which an electronic component is mounted, and an object to be processed is heated and cooled while being conveyed in a reflow chamber and a cooling chamber which are adjacent to each other and which are substantially sealed, to melt the solder. In the reflow soldering device for solidifying and soldering the electronic component to the circuit board, a heat transfer means is provided from the inside to the outside of the cooling chamber. 2. The reflow soldering apparatus according to claim 1, wherein a through-flow blower for blowing the gas cooled by the heat transfer means to the object to be processed is provided in the cooling chamber, and the heat transfer means in the cooling chamber is A reflow soldering device, wherein the reflow soldering device is provided so as to form a space between the suction port of the once-through blower. 3. The reflow soldering device according to claim 1, wherein the heat transfer means is a heat pipe.