JP3406005B2 - Reflow device and reflow method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention runs a circuit board, to which cream solder has been previously supplied, along a transfer path over a plurality of zones in a reflow furnace, while at the same time containing a low oxygen concentration gas containing an inert gas. The present invention relates to a reflow apparatus and a reflow method in which a hot air flow of an oxygen concentration gas is flowed toward a circuit board to perform soldering.

[0002]

2. Description of the Related Art A conventional reflow apparatus that heats and solders a circuit board preliminarily supplied with cream solder in a plurality of zones in a reflow furnace along a transfer path while heating the circuit board in the atmosphere is known. It is described in Kaihei No. 2-137691.

In this type of reflow apparatus, as shown in FIG. 5, a circuit board 4 to which cream solder has been previously supplied.
After being charged into the reflow furnace 43 from the inlet of the carry-in path 42, the No. 1 is moved along the transport path over each zone of the first preheating section 44, the second preheating section 45, the reflow section 46, and the cooling section 49. . Then, the circuit board 41 is gradually heated by the first preheating section 44 and the second preheating section 45, and then further heated by the reflow section 46 to be soldered. Reference numeral 47 is a heating device such as a heater.

Here, as shown in FIG. 5, the first preheating section 4
4. The second preheating section 45 and the reflow section 46 were partitioned by a partition wall 48 partitioning these zones in an adjacent state, and the passage point of the circuit board 41 in this partition wall 48 was simply opened. And this opening 48a
Is formed to have a large passage width so that even a circuit board having the maximum width can pass through.

By the way, when electronic parts are attached to a circuit board in the atmosphere and soldering is performed, the flux in the cream solder scatters or solder balls are generated.
Conventionally, flux residue, solder balls, etc. have been removed by cleaning the soldered mounting substrate with chlorofluorocarbon.

However, since chlorofluorocarbon is a substance that destroys the ozone layer, in recent years, without using chlorofluorocarbon, soldering is performed by introducing air into an inert gas atmosphere at a predetermined temperature, which is generally low-cost nitrogen. A reflow apparatus that performs a mixed low oxygen concentration atmosphere (hereinafter, simply referred to as a nitrogen atmosphere) is being put to practical use. According to this reflow device, since reflow work is performed while preventing oxidation in a low oxygen state due to a nitrogen atmosphere, it is possible to reduce the generation of solder balls, and at the same time, it is preferable to use cream solder with a low content of rosin and the like. Soldering can be performed, and scattered flux can be reduced.

[0007]

However, when the above-mentioned conventional reflow device is applied as a reflow device for reflowing in a nitrogen atmosphere or the like, each zone is partitioned by a partition wall 48 so that the zones are adjacent to each other. Since the passage portion of the circuit board 41 is simply opened with a large passage width, the internal airflow and the external air in each zone are opened in the adjacent zones by the passage portion 4 for passage of the circuit board.
It was not possible to stably secure a low oxygen concentration and an appropriate temperature in each zone because the amount of airflow in and out of each zone increased due to inflow through 8a.

The present invention solves the above problems, and an object of the present invention is to provide a reflow apparatus and a reflow method capable of minimizing the inflow and outflow of the internal airflow and the external air in each adjacent zone. It is what

[0009]

In order to solve the above-mentioned problems, the first means of the present invention is to provide a conveying route over a plurality of zones.
A reflow apparatus having a, toward the transport path
A nozzle with an inverted U-shaped cross section that ejects a hot air stream
Direction in which the opening faces the jet outlet of the nozzle.
Is opened in the same direction as the
A cavity with an area is used as a boundary between the adjacent zones.
One of the nozzles is provided adjacent to the nozzle .
It Further, the second means of the present invention is the solution according to claim 1.
In the flow device, one of the transport routes is the transport route.
A pair of transport guide rails that can move in a direction orthogonal to
Has a ruler and is integrated with the movement of this guide rail for transportation.
A system that closes the movable outer part of the transport route for each zone.
It is characterized by having a hatcher.

The first method of the present invention is a multi-zone method.
Re-soldering while transporting the circuit board across
Flow method, inverted U-shape provided in said zone
A hot air stream is jetted toward the transfer path through the nozzle of the cross section.
Soldering while letting out, the boundary of the adjacent zone
The inverted U-shape provided at the boundary portion and adjacent to the nozzle
Due to the cavity with a larger cross-sectional area than
Causing losses and reducing the velocity of airflow from each zone
Control the air flow between adjacent zones.
Characterize. The second method of the present invention is the same as the first method.
In the method, a pair movable in a direction orthogonal to the transport path is used.
It is possible to move integrally with the movement of the guide rail for transportation that became
With a simple shutter, the area outside the transport route can be
Closed to reduce airflow between adjacent zones
It is characterized by

[0011]

With the first means, the velocity of the air flow from each zone is reduced by the cavity, so that the amount of air flow between the adjacent zones can be minimized.

Further, by the second means, unnecessary portions are opened only pass parts necessary for the circuit board which is conveyed to be more closed to the shutter over the opening area can be suppressed to a minimum, Air flow in and out of adjacent zones is minimized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 3, in the reflow furnace 1, the inlet resistance portions 3, 3 are arranged in order from the upstream side along the transfer path of the circuit board 2 (see FIG. 4) (path between the board transfer directions A).
Preheating first zone section 4, preheating second zone section 5, preheating third zone section 6, reflow first zone section 7, reflow second zone section 8, cooling section 9 and outlet resistance section 10 are provided. ing. Each of these zones 3 to 10 is unitized and filled with nitrogen gas, and the preheating zone portions 4, 5 and 6 and the reflow zone portions 7 and 8 are constituted by the heating unit U (see FIG. 4) having the same configuration. ing.
Then, in this heating unit U, the internal airflow is circulated by the sirocco fan 11 for circulating hot air arranged at the lower part, and in the cooling unit constituting the cooling unit 9, the propeller for circulating cold air arranged at the upper part. The internal airflow is circulated by the fan 12.

As shown in FIG. 4, in each heating unit U, a rear passage 13 extending upward from the rear position of the sirocco fan 11 is formed in the rear portion thereof, and a heater 14 for heating the circulating air flow is provided in the rear passage 13. Has been. In addition, a plurality of flow straightening plates 15 and a blowing nozzle 16 that guide the air flow heated by the heater 14 downward toward the transport path and eject the air flow are disposed in the upper portion. Therefore, the airflow B sent to the heater 14 side by the sirocco fan 11 is heated by the heater 14 and then is jetted from the blowing nozzle 16 toward the transport path while being guided to the straightening plate 15 to heat the circuit board 2. Soldering (reflow zone portions 7 and 8) is performed, and thereafter, the air is again sucked from the upper surface of the sirocco fan 11 and circulated.

In each heating unit U, as shown in FIG. 4, the pseudo substrate plate 20 is provided below the transport path.
Is arranged parallel to the substrate transfer surface,
A plurality of standing plate-shaped portions 21 extending in the substrate width direction are provided on the upper surface of the pseudo substrate plate 20 at predetermined intervals in the substrate transport direction A, and the pseudo substrate plate 20 and the standing plate-shaped portions are provided. With 21, the flow direction of the air flow B ejected from the ejection nozzle 16 is made constant regardless of the presence or absence of the circuit board 2. Reference numeral 17 is a nitrogen gas ejection nozzle for ejecting a low oxygen concentration gas in which nitrogen gas is mixed with air, and 18 is an exhaust duct.

2 to 4, reference numerals 23A and 23B denote a pair of transport guide rails forming a transport path, and a chain conveyor 24 is provided inside each of them. Here, the transport guide rail 23A on the front side is fixed at a predetermined position, while the transport guide rail 23B on the rear side is fixed.
Is slidable in a lateral direction substantially orthogonal to the board transfer direction A, that is, in the width direction of the circuit board 2 to be transferred, so that the circuit boards 2 of various widths can be accommodated. Then, openings 25 are provided at the boundaries of the zones, and the guide rails 2 for transportation penetrate through these openings 25.
3A and 23B are arranged.

Here, as shown in FIG. 1, the blowing nozzle 16 has a plate-like member whose cross section is bent in an inverted U shape and extends in a lateral direction (substrate width direction) substantially orthogonal to the substrate transport direction A. The hot airflow from above is ejected at high speed toward the transfer path, and the airflow that is about to flow parallel to the substrate transfer direction A is rewound. Further, a cavity 26 having a large cross-sectional area in the substrate transport direction A is formed between the zones by a box-shaped frame 26a. The airflow C flowing from each zone toward the adjacent zone flows into the hollow portion 26.

Further, as shown in FIG. 2, a rear guide rail 23 for conveyance which is slidable in the width direction of the circuit board 2.
A shutter mechanism 27 is attached to B. The shutter mechanism 27 includes a shutter body 28 in which strip-shaped plates are laterally connected in a bendable manner,
A bolt 29 is provided at the end of the shutter body 28.
It is composed of a mounting portion 30 fixed to the transport guide rail 23B via a storage frame portion 31, and a storage frame portion 31 disposed on the rear surface side of each zone for storing the shutter body 28 so as to sandwich the shutter body 28 from the front and rear. The front guide rail 2 for transportation
A fixed shutter plate 32 is arranged at a position closer to the front than the opening 25 of 3A.

In the above-mentioned structure, as shown in FIG. 1, the air flow C flowing along the transport path A is the blowing nozzle 16
While the amount is reduced by the lower surface of the zone, it flows into the cavity portion 26 through the opening 25 of each zone boundary portion. However, since this cavity portion 26 is configured by a large space with a large cross-sectional area, Causes a pressure loss, and the velocity of the air flow C from each zone is reduced by the cavity 26. As a result, the amount of airflow in and out of the adjacent zones can be minimized, and a low oxygen concentration and an appropriate temperature in each zone can be stably ensured.

Further, as shown in FIG. 2, at the 25 openings of each zone boundary, the circuit board 2 being conveyed is conveyed.
On the other hand, since the unnecessary portion is closed by the shutter mechanism 27, the opening area can be minimized. Therefore, the inflow / outflow amount of the air flow in each adjacent zone is further reduced, and the low oxygen concentration and the appropriate temperature in each zone can be more stably ensured.

In the above embodiment, the shutter mechanism 27 is attached when only one of the guide rails 23B for conveyance is movable in the substrate width direction, but both guide rails for conveyance also move. It is possible to easily attach a shutter mechanism to each of the possible configurations. Further, instead of attaching the shutter mechanism to the transport guide rail, a mechanism for pressing the shutter mechanism to the transport guide rail side may be provided so that the shutter mechanism can be moved integrally with the transport guide rail. Further, it goes without saying that the above configuration can be applied to a reflow apparatus that uses an inert gas such as argon gas instead of nitrogen gas.

[0022]

As described above, according to the present invention, the conveying path
A nozzle with an inverted U-shaped cross section that ejects a hot air stream toward the
Provided in the zone, the opening of which is the jet outlet of the nozzle
The opening is made in the same direction as the facing direction, and
A cavity with a large cross section is
By providing the boundary portion and the position adjacent to the nozzle, the velocity of the air flow from each zone can be reduced by the cavity, and the flow rate of the air flow in each adjacent zone can be minimized to reduce the low oxygen concentration and The proper temperature in each zone can be stably ensured.

Further , one of the transport paths is the transport path.
A pair of guide rails for transportation that can move in orthogonal directions
And the guide rail for transporting
A shutter that closes the movable outer part of the transport path for each zone.
Since the opening area between the adjacent zones is minimized by providing the heater , this means also minimizes the air flow in and out of the adjacent zones, thereby reducing the low oxygen concentration and each zone. It is possible to stably secure the appropriate temperature in.

[Brief description of drawings]

FIG. 1 is a perspective view of a cavity portion and its vicinity of a reflow device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the zone boundary opening of the reflow apparatus and its vicinity.

FIG. 3 is an overall perspective view of the reflow device when the lid is opened.

FIG. 4 is a partially cutaway perspective view of a heating unit of the reflow apparatus.

FIG. 5 is a sectional view of a conventional reflow apparatus.

[Explanation of symbols]

1 reflow furnace 2 circuit board 3 Entrance resistance section 4, 5, 6 Preheating zone part 7,8 Reflow zone part 9 Cooling unit 10 Exit resistance section 14 heater 16 blow nozzle 23A, 23B Transport guide rails 25 openings 26 Cavity 27 Shutter mechanism 28 Shutter body A board transfer direction B, C air flow U heating unit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimito Kuwahara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Toshinori Mimura 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. In-company (56) Reference JP-A-4-253566 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 3/34

Claims (4)

(57) [Claims] 1. A reflow device having a transport path extending over a plurality of zones, wherein a hot air flow is jetted toward the transport path.
A nozzle with an inverted U-shaped cross section to be taken out is installed in the zone.
The same direction as the direction in which the opening faces the jet outlet of the nozzle.
Has a larger cross-sectional area than the inverted U-shaped cross section.
Was the cavity, the boundary portion of the zone adjacent and said Bruno
A reflow device, which is provided at a position adjacent to a cheat. 2. One of the transport paths is orthogonal to the transport path.
The guide rails for transportation that can move in the direction
It is possible to move integrally with the movement of this transport guide rail
A shutter that closes the outside of the effective transport path for each zone
Reflow apparatus according to claim 1, characterized in that a chromatography. 3. Carrying a circuit board over multiple zones
While reflowing by soldering,
The above-mentioned carrying is carried out through a nozzle having an inverted U-shaped cross section provided in the nozzle.
Soldering while ejecting a hot air stream toward the delivery path
The boundary between the adjacent zones and the adjacent nozzles.
Cross section larger than the inverted U-shaped cross section provided at the position
Due to the cavity with the
Reduce the velocity of the airflow from the
A reflow method characterized by suppressing the flow in and out. 4. A pair that is movable in a direction orthogonal to the transport path.
It is possible to move integrally with the movement of the guide rail for transportation that became
With a simple shutter, the area outside the transport route can be
Closed to reduce airflow between adjacent zones
The reflow method according to claim 3, wherein: