JP3072914B2 - Inert gas atmosphere reflow soldering equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inert gas atmosphere reflow soldering apparatus for carrying a workpiece by a conveyor into a high temperature inert gas atmosphere formed in a reflow furnace and performing reflow soldering. is there.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional inert gas atmosphere reflow soldering apparatus injects an inert gas such as a nitrogen gas into a reflow furnace 11 and uses a heater 12 and a stirrer 13 to perform the same. A high-temperature inert gas atmosphere is formed, and the workpiece W (with electronic components mounted thereon via a solder paste printed on a substrate) is carried into the high-temperature inert gas atmosphere by the conveyor 14 and heated. Accordingly, soldering is performed by reflowing the solder paste.

It is known that the lower the oxygen concentration in the furnace by injecting an inert gas into the reflow furnace 11, the better the reflowed solder wets and spreads, and the more the generation of solder balls can be prevented.

The reflow furnace 11 has a work loading section 15 and a work unloading section 16, and the conveyor 14 for transporting the work is provided from the work loading section 15 to the work unloading section 16.

[0005]

A reflow furnace of this kind 11
Has a work introduction part 15 and a work discharge part 16 formed in a straight duct shape, and the work introduction part 15 and the work discharge part 16 have to form a continuous passage with the outside. A large amount of the inert gas injected into the furnace 11 leaks from the work carry-in portion 15 and the work carry-out portion 16 to the outside.

For this reason, it is necessary to inject a large amount of expensive inert gas into the furnace in order to keep the inside of the furnace at a low oxygen concentration. Otherwise, a large amount of outside air (oxygen) is supplied to the work loading section 15. In addition, there is a problem that the solder enters the reflow furnace 11 from the work discharge section 16 and hinders good soldering.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is an object of the present invention to reduce the amount of inert gas injected into a reflow furnace and to maintain a predetermined low oxygen concentration in the furnace. It is an object to provide a mounting device.

[0008]

According to the first aspect of the present invention, a work W is carried by a conveyor 14 into a high-temperature inert gas atmosphere formed inside a reflow furnace 11 and reflow soldering is performed. In the active gas atmosphere reflow soldering equipment, at least the work loading section of the reflow furnace 11
Inside the workpiece 15 and the work unloading section 16, a passage 26 whose cross-sectional shape can be freely changed according to the change in the width of the work is provided along the work transfer path, and an intermediate portion of the passage 26 has a large opening area. This is an inert gas atmosphere reflow soldering apparatus provided with a chamber 41.

The second aspect of the present invention is an inert gas atmosphere reflow soldering apparatus in which a partition plate 42 having a reduced opening area is provided inside an expansion chamber 41 having a large opening area.

A third aspect of the present invention is an inert gas atmosphere reflow soldering apparatus in which a gas injection port 44 is provided in an expansion chamber 41 having a large opening area.

A fourth aspect of the present invention is an inert gas atmosphere reflow soldering apparatus in which a gas outlet 45 is provided in an expansion chamber 41 having a large opening area.

The invention according to claim 5 is an inert gas atmosphere reflow soldering apparatus in which a gas inlet 44 and a gas outlet 45 are provided in an expansion chamber 41 having a large opening area.

[0013]

According to the first aspect of the present invention, the outside air (oxygen) hardly enters the furnace by the narrow passage 26, and the inert gas in the narrow passage 26 rapidly expands in the expansion chamber 41 having a large opening area. As a result, the gas pressure is reduced and energy is lost, and the inert gas exiting from the expansion chamber 41 becomes laminar in the passage portion 26, thereby preventing entrainment of outside air due to turbulent flow.

According to the second aspect of the present invention, since the expansion chamber 41 is divided into a plurality of chambers by the partition plate, the operation of the second aspect is repeated twice or three times.

According to the third aspect of the present invention, since the outside air entry path is cut off by the expansion chamber 41 filled with the inert gas or the like injected from the gas injection port 44, the outside air (oxygen) is prevented from entering the furnace. Prevent surely.

According to a fourth aspect of the present invention, an inert gas containing a flux component in the furnace is exhausted from a gas outlet 45.
At this time, the outside air (oxygen) which is going to enter the reflow furnace 11 from the outside is also sucked into the gas discharge port 45, and it is hard to enter the furnace further deeper.

According to a fifth aspect of the present invention, the outside air intrusion path is cut off by the expansion chamber 41 filled with an inert gas or the like injected from the gas injection port 44, and at the same time, the gas injected from the gas injection port 44 is cut off. The gas containing the flux component in the furnace is exhausted from the gas outlet 45. At this time, the outside air (oxygen) that tries to enter the reflow furnace 11 from the outside also has a gas outlet.
Suck into 45 and do not allow it to enter further into the furnace.

[0018]

EXAMPLES The following assumptions indicated the present invention in FIGS. 1 to 4
With reference to the technology, with reference to which Ru Kazumi施例that shown in FIG. 5 will be described in detail. Note that the same reference numerals are given to the common parts between the base technology and the embodiment , and the description will be omitted .

As shown in FIG. 1A, a reflow furnace
The interior of 11 is divided into two parts by a partition 21 to form a preheat chamber 22 on the work carry-in side and a reflow chamber 23 on the work carry-out side.

An inert gas inlet 24 for injecting an inert gas such as nitrogen gas into the preheat chamber 22 and the reflow chamber 23 is provided below the reflow furnace 11. Also, the preheat chamber
Inside the 22 and the reflow chamber 23, a heater 12 for heating the inert gas atmosphere and a stirrer 13 for stirring the inert gas atmosphere to obtain a uniform temperature distribution are respectively provided as in the related art. . The preheat chamber 22 is maintained at a relatively low preheat temperature, while the reflow chamber 23 is maintained at a high reflow temperature.

The provision of a duct-like work carry-in section 15 for the preheat chamber 22 and the provision of a duct-like work carry-out section 16 for the reflow chamber 23 are the same as in the prior art. Further, an intermediate duct 25 is provided in the partition 21.

In the work carry-in portion 15, the intermediate duct 25 and the work carry-out portion 16 of the reflow furnace 11, a passage portion 26 whose cross-sectional shape can be freely changed according to the change of the work width is provided along the work transfer path. The passage 26 has a work through hole 27 whose opening area is smaller than that of the work carry-in portion 15, the intermediate duct 25, and the work carry-out portion 16. A conveyor 14 for conveying the work is provided through a work through hole 27 in each of the passages 26 provided in each of the parts.

As shown in FIG. 1B, the conveyor 14 is provided with an endless fixed frame 14a on one side and a movable conveyor frame 14b for width adjustment on the other side, as shown in FIG. 1A. The chains are mounted, the work W is engaged between the pins 14c protruding from the endless chains on both sides, and the endless chains on both sides are synchronously rotated and driven to carry the work W.

This work W has electronic components mounted thereon via a solder paste printed on a printed wiring board.

The passage 26 extends over the entire length of the work carry-in portion 15, the intermediate duct 25 or the work carry-out portion 16 as shown in FIG.
A fixed frame 26a shown in (B) is fixed, and a movable frame 26b that is paired with the fixed frame 26a is slidably provided along the guide rail 28. The work through hole 27 is formed in the fixed frame 26a, the movable frame 26b, and the upper and lower bellows 26c by extending the bellows 26c between the upper part and the lower part of the fixed frame 26a and the movable frame 26b. .

The fixed conveyor frame 14a and the fixed frame 26a are both fixedly installed at fixed positions, and the movable conveyor frame 14b and the movable frame 26b are integrated by a connecting portion 29 to move and adjust integrally.

Openings at both ends of a space 30 formed between the work carry-in portion 15, the intermediate duct 25 and the work carry-out portion 16 and the corresponding passages 26 are provided with bellows as shown in FIG. Is closed by a telescopic member 31 such as silicone rubber.

Next, the operation of the base technology shown in FIG. 1 will be described.
5, preheat chamber 22, reflow chamber 23 and work unloading section 1
Transport in the order of 6. Then, the work W in the preheat chamber 22
Is preheated, the solder paste of the work W is reflowed in a high temperature inert gas atmosphere in the reflow chamber 23, and the board and the component are soldered.

At this time, the inert gas such as the nitrogen gas injected into the reflow furnace 11 from the inert gas inlet 24 always flows through the work passages 26 provided in the work carry-in section 15 and the work carry-out section 16. The gas is exhausted to the outside through the through hole 27, but due to the opening area narrowed by the passage 26, the amount of the inert gas discharged to the outside through the work carry-in portion 15 and the work carry-out portion 16 is reduced. Therefore, the passage speed of the inert gas through the passage 26 is increased, and there is little possibility that outside air (oxygen) enters the furnace. According to experiments, when the inert gas passage speed is about 15 cm / sec or more, entry of oxygen-containing atmosphere into the furnace can be substantially prevented.

The passage 26 provided in the intermediate duct 25
Is the inert gas atmosphere in the preheat chamber 22 and the reflow chamber 23
To maintain a predetermined temperature difference with the inert gas atmosphere.

When the width of the workpiece is changed, the movable conveyor frame 14a is moved relative to the fixed conveyor frame 14a.
1B is moved and adjusted in the left and right direction in FIG. 1 (B) to change the conveyor frame interval, so that the movable frame 26b integrated with the movable conveyor frame 14b via the connecting portion 29 also slides on the guide rails 28, and the fixed frame The distance between 26a and movable frame 26b automatically changes. At that time, bellows 26c
Expands and contracts.

Next, as in the passage 26 shown in FIG.
A rubber film 26d such as silicon rubber may be provided between an upper portion and a lower portion of the fixed frame 26a and the movable frame 26b. In this case, the expansion and contraction of the rubber film 26d corresponds to the width adjustment movement of the conveyor frame 14b.

Next, in the passage portion 26 shown in FIG. 3, a fixed plate 26e is integrally mounted on upper and lower portions of a fixed frame 26a, and a movable plate 26f is integrally mounted on upper and lower portions of a movable frame 26b. 26f, a film (thin stainless steel plate, etc.) that slidably overlaps with the fixing plate 26e
By integrally providing g, the distance between the fixed frame 26a and the movable frame 26b can be freely changed according to the work width. The surplus portion of the film 26g is a winding shaft
Take up by 32. The take-up shaft 32 is preferably configured to rotate in conjunction with the movement of the conveyor frame 14b by a pinion rack or the like.

When the width of the work is changed, the movable conveyor frame 14a is moved relative to the fixed conveyor frame 14a.
The movable frame 26b integrated with the movable conveyor frame 14b via the connecting portion 29 slides following the movable conveyor frame 14b via the connecting portion 29, and slides, thereby moving the work in the passage portion 26. The entire width of the hole 27 changes automatically. At this time, when the movable plate 26f approaches the fixed plate 26e, the film 26g integral with the movable plate 26f is wound by the winding shaft 32, and when the movable plate 26f is separated from the fixed plate 26e. The film 26g is unwound from the winding shaft 32.

Next, the passage portion 26 shown in FIG. 4 includes a plurality of slide plates 26h, slidably engaged with each other between an upper portion and a lower portion of the fixed frame 26a and the movable frame 26b.
By extending the respective 26i and 26j, the distance between the fixed frame 26a and the movable frame 26b can be freely changed according to the work width.

When the work width is changed, the movable conveyor frame 14a is fixed to the fixed conveyor frame 14a.
b is moved in the left and right direction in FIG. 4 to change the conveyor frame interval, so that the connecting portion is connected to the movable conveyor frame 14b.
The movable frame 26b integrated via 29 follows and slides, and the entire width of the work through hole 27 in the passage portion 26 automatically changes.

FIG. 5 shows an embodiment of the present invention .
An expansion chamber 41 having a large opening area is provided at an intermediate portion of the passage portion 26 of the work carry-in portion 15 and an intermediate portion of the passage portion 26 of the work carry-out portion 16.

Further, a partition plate 42 is provided inside the expansion chamber 41 having a large opening area. A work passage opening 43 having a reduced opening area is formed in the work transfer portion of the partition plate. And, a gas inlet 44 is provided at the lower part of the expansion chamber 41,
An inert gas such as a nitrogen gas or a reducing gas such as an organic acid gas is injected from the gas inlet 44 into the expansion chamber 41. In addition, a gas outlet 45 is provided in the upper part of the expansion chamber 41,
This is connected to the intake side of the blower. The gas inlet 44 and the gas outlet 45 are provided on the opposite side via the partition plate 42, so that the gas moving from the gas inlet 44 to the gas outlet 45 always passes through the work passage opening 43 of the partition plate 42. Pass through.

The operation of the embodiment shown in FIG. 5 is as follows.
The inert gas which is about to flow out through the narrow passage portion 16 rapidly expands in the expansion chamber 41 having a large opening area on the way, and the gas pressure is reduced to lose energy. The inert gas flowing out through the passage portion 26 after 41 becomes laminar flow in the work through hole 27 in the passage portion 26, preventing the outside air from being trapped by the turbulent flow, and preventing the outside air from entering the furnace. There is work.

Since the partition plate 42 in the expansion chamber 41 divides the expansion chamber 41 into a plurality of chambers, the operation of the expansion chamber 41 is doubled, triple, and triple.
It is performed repeatedly and the effect is amplified.

Further, by injecting an inert gas such as a nitrogen gas or a reducing gas such as an organic acid gas into the inside of the expansion chamber 41 from the gas injection port 44, the expansion chamber 41 filled with the inert gas or the like is injected. This cuts off the outside air intrusion path, so that outside air (oxygen) can be reliably prevented from entering the furnace. In particular, when the inert gas or the like injected into the expansion chamber 41 from the gas inlet 44 moves through the work passage opening 43 of the partition plate 42 in the direction opposite to the outside air inflow direction, the inert gas or the like moves to the gas outlet 45 Therefore, the effect of preventing outside air from entering is high.

At the same time, an inert gas containing a flux component in the furnace is sucked out from the gas discharge port 45 and exhausted. At this time, the reflow furnace 11
The outside air (oxygen) which is going to enter the inside is also sucked out from the gas outlet 45, and is not allowed to enter the furnace further behind.

[0043]

According to the first aspect of the present invention, the expansion chamber having a large opening area is provided in the middle of the passage, so that the outside air (oxygen) hardly penetrates into the furnace due to the narrow passage, and is narrow. When the inert gas in the passage portion rapidly expands in the expansion chamber having a large opening area, the gas pressure is reduced and energy is lost, and the inert gas exiting from the expansion chamber becomes laminar in the passage portion and is caused by turbulent flow. It is possible to prevent entrainment of outside air. This
The expansion chamber works to prevent outside air from entering the furnace.
The amount of inert gas injected into the reflow furnace
Can be reduced, and the inside of the furnace can be maintained at a predetermined low oxygen concentration.
Soldering can be secured.

According to the second aspect of the present invention, since the partition plate is provided inside the expansion chamber, the effect of the second aspect is amplified in a double or triple manner in the expansion chamber divided into a plurality of sections by the partition plate. can do.

According to the third aspect of the present invention, since the gas injection port is provided in the expansion chamber, the expansion chamber filled with the inert gas or the like injected from the gas injection port cuts off the external air intrusion path, and (Oxygen) can be reliably prevented from entering the furnace.

According to the fourth aspect of the present invention, since the gas exhaust port is provided in the expansion chamber, the inert gas containing the flux component in the furnace is exhausted from the gas exhaust port, and at the same time, the gas enters the reflow furnace from the outside. The outside air (oxygen) is also sucked into the gas discharge port, so that it can be prevented from entering the furnace further behind.

According to the fifth aspect of the present invention, the gas inlet and the gas outlet are provided in the expansion chamber having a large opening area.
The expansion chamber filled with the inert gas or the like injected from the gas inlet can cut off the outside air intrusion path. Further, the gas injected from the gas inlet and the gas containing the flux component in the furnace are discharged. At the same time as the air can be exhausted from the outlet, the outside air (oxygen) that is going to enter the reflow furnace from the outside can also be sucked into the gas discharge port, thereby preventing the furnace from entering further into the furnace.

[Brief description of the drawings]

FIG. 1A is a sectional view showing a prerequisite technique of an inert gas atmosphere reflow soldering apparatus of the present invention. B is a sectional view showing a first example of a passage used in the reflow soldering apparatus.

FIG. 2 is a cross-sectional view showing a second example of the passage section.

FIG. 3 is a cross-sectional view showing a third example of the passage section.

FIG. 4 is a sectional view showing a fourth example of the passage section.

5 is a sectional view showing an embodiment of an inert gas atmosphere reflow soldering apparatus of the present invention.

FIG. 6 is a sectional view showing a conventional inert gas atmosphere reflow soldering apparatus.

[Explanation of symbols]

 W Work 11 Reflow furnace 14 Conveyor 15 Work carry-in part 16 Work carry-out part 26 Passage part 41 Expansion chamber 42 Partition plate 44 Gas inlet 45 Gas outlet

Continuing from the front page (72) Inventor Mamoru Fujii 1-19-43 Higashi-Oizumi, Nerima-ku, Tokyo Inside the Tamura Manufacturing Co., Ltd. (72) Inventor Kazuo Outo 1-19-43 Higashi-Oizumi, Nerima-ku, Tokyo (72) Inventor Toshiya Uchida 1-19-43, Higashi-Oizumi, Nerima-ku, Tokyo, Japan Stock Company (72) Inventor Kannobu Abe 1-19-143, Higashi-Oizumi, Nerima-ku, Tokyo, Japan (56) References JP-A-62-148083 (JP, A) JP-A-4-200862 (JP, A) JP-A-63-101171 (JP, U) (58) Fields investigated ( Int.Cl. ⁷ , DB name) B23K 1/008 B23K 31/02 310 H05K 3/34 507

Claims (5)

(57) [Claims] 1. An inert gas atmosphere reflow soldering apparatus for carrying a reflow soldering by carrying a work by a conveyor into a high temperature inert gas atmosphere formed inside a reflow furnace. Inside the section and the work discharge section, a passage section is provided along the work transfer path that allows the cross-sectional shape to be freely changed according to the change in the work width, and an expansion chamber with a large opening area is provided in the middle of this passage section. An inert gas atmosphere reflow soldering apparatus. Wherein the interior of a large expansion chamber opening area claim 1, characterized in that a partition plate which narrows the opening area
An inert gas atmosphere reflow soldering apparatus as described. 3. A large expansion chamber an inert gas atmosphere reflow soldering apparatus according to claim 1, wherein in that a gas injection port opening area. 4. A large expansion chamber an inert gas atmosphere reflow soldering apparatus according to claim 1, wherein in that a gas outlet to the opening area. 5. Also according to claim 1, characterized in a large expansion chamber opening area to the provision of the gas inlet and gas outlet
Is an inert gas atmosphere reflow soldering apparatus according to 2.