WO2007023604A1

WO2007023604A1 - Reflow furnace

Info

Publication number: WO2007023604A1
Application number: PCT/JP2006/310961
Authority: WO
Inventors: Issaku Sato
Original assignee: Senju Metal Industry Co., Ltd.
Priority date: 2005-08-23
Filing date: 2006-06-01
Publication date: 2007-03-01
Also published as: JP4100578B2; JPWO2007023604A1

Abstract

[PROBLEMS] To solve problems in a conventional reflow furnace having a large number of discharge ports and suction ports formed near the discharge ports wherein tall parts are thermally damaged and printed circuit boards are nonuniformly heated. [MEANS FOR SOLVING THE PROBLEMS] This reflow furnace is so formed that zigzag plate-like nozzles having a large number of jetting holes formed in the upper part thereof are projected from the surface of a heater. Furthermore, a plurality of blocks forming the plate-like nozzles are formed movable in the vertical direction.

Description

Specification

Reflow furnace

Technical field

TECHNICAL FIELD [0001] The present invention relates to a reflow furnace for performing soldering by melting a solder paste applied to a printed circuit board.

Background art

[0002] When soldering a printed circuit board and an electronic component using solder paste, it is generally performed in a reflow furnace. In the reflow furnace, the tunnel-shaped pinefull is composed of a preheating zone, a main heating zone, and a cooling zone. A heater is installed in the preheating zone and the main heating zone, and a cooler is installed in the cooling zone. And

[0003] As heaters used in the reflow furnace, there are an infrared heater and a hot air blowing heater. The infrared heater penetrates the printed circuit board and electronic equipment, and melts the solder paste applied to the soldering part. In addition, there was a problem that the soldered part that becomes a gap could not be heated sufficiently.

[0004] On the other hand, in the hot air blowing heater, since hot air convects in the Matsufuru, the hot air enters the shadows of electronic components and narrow gaps, so the entire printed circuit board is more uniform than infrared heaters. It can be heated to a high temperature and is widely used in reflow furnaces today.

[0005] A hot air blowing heater installed in a conventional reflow furnace has a large area hot air outlet and a small area adjacent to the hot air outlet. Hot air blowout loca of area A large amount of hot air was blown out and applied to the printed circuit board, and a large area of the printed circuit board was heated at once. Large area blowout force It was thought that blowing hot air would be able to heat the printed circuit board uniformly, but recent experimental results revealed that even if large area force hot air is blown, uniform heating is not possible. did. That is, a large area hot air blowing loca also blows hot air to heat the printed circuit board, and then the heated printed circuit board advances and reaches the suction port. If it does not hit, the printed circuit board is cooled instead of sucking in hot air. Therefore, when we draw a temperature profile in a reflow furnace in which a hot air outlet with a large area and a hot air inlet with a small area are installed adjacent to each other, the temperature rises at the hot air outlet. The temperature may drop. In this way, if the temperature fluctuates in the preheating zone or the main heating zone, the printed circuit board will not be heated uniformly, resulting in partial overheating or insufficient heating, resulting in thermal damage to electronic components or unmelted solder paste. It may become.

[0006] In view of the problem of the reflow furnace that blows hot air from these large area blowers, a large number of small hot air outlets and continuous hot air outlets are provided, and a large number of hot air blowers are also provided in the vicinity of these hot air outlets. Hot air sucking! Intrusion and continuous hot air sucking! A reflow furnace with a slot has been proposed (Patent Documents 1 to 7).

Patent Document 1: Japanese Patent Laid-Open No. 2-303674

Patent Document 2: JP 2001-144426 A

Patent Document 3: Japanese Patent Laid-Open No. 2001-144427

Patent Document 4: Japanese Patent Laid-Open No. 2001-326455

Patent Document 5: Japanese Patent Laid-Open No. 2002-198642

Patent Document 6: Japanese Patent Application Laid-Open No. 2002-331357

Patent Document 7: Japanese Patent Laid-Open No. 2003-332725

Disclosure of the invention

Problems to be solved by the invention

[0007] By the way, electronic components with high height (hereinafter referred to as vertical height components) may be mounted on a printed circuit board. When soldering a printed circuit board equipped with vertical components in this way in a reflow furnace with a suction port near the hot air outlet, the vertical component near the hot air outlet heats up quickly. The temperature of other electronic components away from the hot air outlet is slow. As a result, there is a problem that the entire printed circuit board is not uniformly heated. In addition, if the temperature rises slowly, trying to raise the part to the specified soldering temperature, the temperature rises too quickly at the part where the temperature rises quickly, such as a vertical component, and the electronic parts are thermally damaged. It will be. Moreover, in the reflow furnace which provided the suction inlet near the conventional hot-air outlet, When inert gas was used due to turbulent flow in Matsufuru, there was a problem that outside air entered and raised the oxygen concentration. An object of the present invention is to provide a reflow furnace in which the oxygen concentration is stabilized even if the printed circuit board on which the vertical components are mounted can be heated evenly even if it is in an inert atmosphere.

Means for solving the problem

[0008] In the reflow furnace in which the hot air blowing heater is installed, the present inventor installs a plate-like nozzle for blowing hot air from the hot air blowing heater and a plurality of suction and suction ports for sucking the hot air, each having a zigzag shape. The present invention has been completed by finding that the whole can be heated evenly, no force or turbulence occurs, and that the hot air outlet is at a distance corresponding to the vertical height component, so that uneven heating does not occur. .

[0009] The present invention provides a zigzag plate-like plate projecting from the heater surface at the top or top and bottom of the preheating zone and the main heating zone in a reflow furnace having preheating zone, main heating zone and cooling zone forces. A plurality of nozzles are arranged in a direction crossing the direction of travel of the printed circuit board, each plate-like nozzle is configured with a plurality of block forces, and each block is movable in the vertical direction. In addition, the reflow furnace is characterized in that a suction force is also formed in the vicinity of the plate-like nozzle.

[0010] In the present invention, the plate-like nozzles are arranged in the upper part or the upper and lower parts of the preheating zone and the main heating zone. That is, in general, a printed circuit board is often coated with a solder paste on the top, and electronic components are often mounted on the coated part. Therefore, if only the top of the printed circuit board is heated with hot air, the solder paste can be melted. However, in order to uniformly heat the entire printed circuit board, it is necessary to heat the lower part of the printed circuit board. In this case, the zigzag plate-like nozzle force used in the present invention is blown with hot air. The hot air blown out from the nozzle used in the conventional reflow furnace may be used, or far infrared rays may be used. The hot air blowing heater used in the present invention is basically installed at the upper part of the reflow furnace in order to move the block forming the plate-like nozzle up and down according to the height of the electronic parts and the like.

[0011] The nozzle plate of the hot air blowing heater used in the present invention has a zigzag shape. This zigzag nozzle plate has the effect of uniformly heating the printed circuit board. In other words In a reflow furnace in which several nozzle plates are arranged, when the nozzle plates are arranged in a straight line and in parallel, no hot air is blown between the nozzle plate and the nozzle plate adjacent to the nozzle plate. When the printed circuit board passes through this dead zone, a portion of the printed circuit board that is not heated linearly is formed. Therefore, in a reflow furnace in which a linear nozzle plate is arranged, the printed circuit board is heated in a striped pattern laterally in the traveling direction and is not heated, and the entire printed circuit board is hardly heated uniformly. However, when the plurality of nozzle plates are zigzag-shaped, even if a dead zone is formed between the nozzle plate and the nozzle plate disposed adjacent to the nozzle plate, there is always a heated portion on the side. Therefore, in this reflow furnace, even if there are a heating part and a non-heating part on the side, both sides of the non-heating part are heating parts, so the heat of the heating part heats the non-heating part and prints. The entire substrate is heated uniformly.

[0012] Further, in the present invention, since the plate-like nozzle force heater surface force of the hot air blowing heater protrudes, the portion surrounded by a pair of adjacent plate-like nozzles and the heater surface and the printed circuit board has a constant temperature. It becomes a heated area. In other words, in the heating area, when hot air blown from the ejection holes of the protruding plate nozzle hits the printed circuit board and returns to the suction port formed on the heater surface, heat is accumulated in the heating area and becomes a constant temperature. That is why. The heating area is formed long in the lateral direction of the printed circuit board, and the heating area sequentially exists with the progress of the printed circuit board. Therefore, the printed board conveyed by the conveying apparatus is further heated evenly together with the zigzag nozzle plate.

In the reflow furnace of the present invention, a zigzag plate-like nozzle is formed by combining a plurality of blocks, and each block can be moved up and down. In other words, by moving the block up and down, the ejection hole force of the block can be adjusted to the vertical height of the printed circuit board. Therefore, by pushing the block of the part through which the vertical height part passes into the back and separating the ejection hole of the block to the vertical height part, the vertical height part is not overheated, and the vertical height part and other parts are heated. The state becomes uniform.

[0014] In the reflow furnace of the present invention, since the blocks moved up and down must be stopped at appropriate places, a locking plate is erected between the blocks. A locking device is installed on the block or locking plate. As the locking device, any structure can be used as long as it can reliably stop the block at a predetermined position! /, But the structure is simple and the locking can be reliably performed. Net-biased balls and cones are suitable. When a panel-biased ball or cone locking device is installed in the block, a plurality of recesses are provided in the locking plate so that the ball or cone can be easily fitted. In this way, the panel urging ball or cone locking device ensures that the block stays in place by simply moving the block in the vertical direction and locking the ball or cone in the appropriate recess.

[0015] In the hot air blowing heater used in the reflow furnace of the present invention, the suction port is formed on the heater surface between the plate-like nozzles, or the suction port is formed in a zigzag shape along the plate-like nozzle. Alternatively, it may be formed in a zigzag shape in the approximate center between adjacent plate nozzles. The suction holes formed on the heater surface are preferably zigzag with the same pitch as the plate nozzles, but other shapes, for example, punching plates with many holes formed on the heater surface, have many slits. It may be a snowboard that has been made. As the punching plate can be used on the market, there is no need to create a suction port when manufacturing the hot air blowing heater.

[0016] The plate-like nozzle of the hot air blowing heater used in the reflow furnace of the present invention has a blowing port, and the blowing loca also blows hot air and hits the printed board to heat the printed board. Is. The blowout port is a slit or the like, but a hole is preferable to a slit. This is because hot air can be faster in the hole than in the slit, enabling rapid heating and increasing productivity.

[0017] Since the opening area of the hole as the blowout port is small, the hot air blowout speed is much faster than that of the slit, so that rapid heating is possible and the productivity is excellent. However, the hole can be heated sufficiently just below the hole. When the hole is removed from directly below the hole, the temperature is lower than that below the hole, resulting in uneven heating. Therefore, it has been considered difficult to uniformly heat a hot air blowing heater using holes. Therefore, a large number of ejection holes are formed in the plate-shaped nozzle, and the ejection holes are not located at the same position as the ejection holes of the adjacent plate-shaped nozzles with respect to the traveling direction of the printed circuit board. It is drilled at the same position as the ejection hole of the plate-like nozzle separated as described above. In this way, if the ejection holes are formed so as to be shifted from the adjacent plate-like nozzles, the temperature at which the force directly below the ejection holes is displaced by the first plate-like nozzle is also obtained. Even if a low-temperature part is formed, the ejection hole of the next plate-like nozzle comes to heat up by applying hot air to the low-temperature part.

The invention's effect

[0018] According to the present invention, since a plurality of zigzag plate-like nozzles are formed in a direction crossing the traveling direction of the printed circuit board, any portion with respect to the printed circuit board running in the reflow furnace. Also, hot air is always applied, and the printed circuit board is heated uniformly. In the reflow furnace of the present invention, a zigzag plate-like nozzle is formed of a plurality of blocks.

Since the block can also move up and down, the distance to the jetted loca vertical height component can be adjusted by adjusting the position of the block where the vertical height component passes. There is no overheating. Furthermore, the reflow furnace of the present invention has a plate-like nozzle force, a heater surface force protruding, and thus forms a horizontally long heating region in which the temperature is constant between adjacent plate-like nozzles, and the printed circuit board advances. In contrast, the heating area performs uniform heating. In the reflow furnace of the present invention, since the heating region performs self-convection, outside air does not enter and the low oxygen concentration can be kept stable.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the reflow furnace of the present invention will be described with reference to the drawings. Fig. 1 is a front cross-sectional view of the reflow furnace of the present invention, Fig. 2 is a front cross-sectional view of a hot air blowing heater installed in the reflow furnace of the present invention (however, only the nozzle plate is a cross section along the center of the zigzag), and Fig. 3 4 is a partial perspective view of the hot air blowing heater installed in the reflow furnace according to the present invention (however, facing upward for easy understanding), FIG. 5 is a plan view of FIG. 4, and FIG. 6 is a portion of FIG. It is an enlarged view.

[0020] As shown in FIG. 1, the reflow furnace 1 of the present invention has a tunnel-like pinefull 2 formed in the longitudinal direction, and this pinefull is connected to a preheating zone 3, a main heating zone 4, and a cooling zone 5. ing. Multiple (three pairs) hot air blowing heaters 6 · · 'are installed in the upper and lower parts of the preheating zone 3, and multiple (two pairs) hot air blowing heaters 7 are installed in the upper and lower parts of the heating zone 4. Is installed. The hot air blowing heater 6 installed in the preheating zone 3 and the hot air blowing heater 7 installed in the main heating zone 4 have almost the same structure. The hot air blowing heater 7 installed in the main heating zone is heated by the hot air blowing installed in the preheating zone. However, the width in the conveying direction is shorter than that of heater 6. The cooling zone 5 is provided with a pair of coolers 8 and 8 that do not clearly show the structure for cooling the printed circuit board after soldering. In Matsufuru 2, there is a conveyor 9 that transports the printed board P from the preheating zone 3 to the cooling zone 5 (arrow X).

[0021] Here, the hot air blowing heater installed in the reflow furnace of the present invention will be described. Since the hot air blowing heater installed in the preheating zone and the hot air blowing heater installed in the main heating zone have the same structure, the hot air blowing heater installed in the preheating zone will be described here.

[0022] The hot air blowing heater 6 has a box shape and is divided into four chambers in the vertical direction. As shown in FIGS. 2 and 3, these four chambers are a blower chamber 10, a heating chamber 11, a hot air chamber 12, and a suction chamber 13 from the top.

A blower 14 is placed in the center of the blow chamber 10. This blower is a sirocco fan and is linked to an external motor 15. On both sides of the air blowing chamber 10, there are partition walls 16 (not shown), and one end of each partition wall is an opening 17. The opening of each partition wall is not an opposite position but a separated end.

[0024] In the heating chamber 11, channels 18 and 18 are formed on both sides, and a plurality of electric heaters 19 are arranged inside the heating chamber. A suction hole 21 is formed in the partition plate 20 that separates the heating chamber 11 and the blower chamber 10. The suction hole is located directly above the blower 14, and its diameter is slightly smaller than the diameter of the sirocco fan that is the blower.

[0025] The hot air chamber 12 communicates with the opening 17 of the air blowing chamber 10, and hot air is sent from the air blowing chamber 10! / Speak. A partition plate 22 is stretched between the hot air chamber 12 and the suction chamber 13, and the suction chamber 13 communicates with the heating chamber 11 through a flow path 18. The upper surface of the suction chamber 13 is a heater surface 23. .

A plurality of zigzag plate-like nozzles 24... Stand up from the heater surface 23 on the partition plate 22. In this standing state, a block forming a plate-like nozzle, which will be described later, is fitted so as to be movable up and down, and the block and the partition plate are sealed. The plurality of zigzag plate-like nozzles 24 are arranged in a direction transverse to the advancing direction of the printed circuit board (arrow X) as shown in FIGS. The plate nozzle 24 has a large number of ejection holes 25. It is drilled through. On both sides of the plate-like nozzle 24, suction and intake ports 26 are formed along the plate-like nozzle!

[0027] The zigzag plate-like nozzle 24 is composed of a plurality of blocks 27. The block may be any part of the edges that make up the zigzag shape. As the block shape, for example, a V-shaped portion, a W-shaped portion, or a combination of a plurality of V-shaped portions in a zigzag shape may be used to increase the block length. In the embodiment of the present invention, the block is a V-shaped part. The block 27 is fitted to the partition plate 22 so as to be movable up and down.

[0028] Locking plates 28 are erected on both sides of the block 27, and the locking plates are fixed to the partition plate 22. Therefore, the block 27 can move in the vertical direction as indicated by the arrow Y in FIG. Further, locking devices 29 are embedded on both sides of the block 27 as shown in FIG. In the locking device 29, the ball 30 is pressed outward by the compression panel 31, and a part of the ball 30 protrudes from the locking device 29. A plurality of recesses 32 having substantially the same shape as a part of the ball 30 of the locking device 29 are formed on both sides of the locking plate 28 in the vertical direction.

Next, soldering of the printed circuit board in the reflow furnace having the above structure will be described. First, before soldering the printed circuit board on which the vertical component H is mounted, the preheating hot air blowing heater 6 and the main heating hot air blowing heater 7 installed on the upper part of the pine-fur 2 of the reflow furnace 1 Make adjustments. This adjustment means that the block 27 of the plate-like nozzle 24 above which the vertical height component H of the printed circuit board P passes is moved upward as shown in FIGS. This movement is to move the block 27 so that the distance between the upper part of the vertical component H and the ejection hole 25 of the block 27 is substantially the same as the distance between the other electronic components D of the printed circuit board P.

[0030] Thereafter, the electric heater 19 disposed in the heating chamber 11 is energized and the motor 15 is driven to rotate the sirocco fan as the blower 14. Then, the gas in the heating chamber 11 is heated by the electric heater 19 and becomes hot hot air, and is drawn into the blower chamber 10 from the suction side of the blower by the blower 14. The hot air drawn into the blower chamber 10 is sent from the blower blowout side of the blower 14 through the opening 17 to the hot air chamber 12 by the blower 14 and further blown out from the ejection holes 25 of the plurality of plate-like nozzles 24. The In Matsufuru 2, the printed circuit board P is driven by the conveyor 9, and the plate-like nozzles 24 are jetted to the printed circuit board P that travels. The hot air blown from the outlet 25 ··· hits the printed circuit board here. When the printed circuit board is heated by hot air, the solder paste applied to the soldering part melts, and the printed circuit board and electronic components are soldered. At this time, since the zigzag plate-like nozzles 24... Protrude from the heater surface 23, there is no portion where the hot air does not hit the printed circuit board, and all the portions are uniformly heated by the hot air. Therefore, there is no partial overheating or unmelting of the solder paste.

[0031] The hot air blown out from the plate-like nozzle force loses its heat to the printed circuit board, so the temperature drops. The hot air whose temperature has thus decreased is sucked into the suction port 26 in the vicinity where the plate-like nozzle 24 is erected as shown in FIG. 3, and enters the heating chamber 11 through the flow path 18. The hot air entering the heating chamber 11 is heated to a predetermined temperature by the electric heater 19 and sucked into the blower chamber 10 by the blower 14. Then, the hot air is sent from the opening 17 to the hot air chamber 12 and is blown out again from the ejection holes 25 ··· of the plate nozzle 24 to heat the printed circuit board. That is, in the reflow furnace of the present invention, the hot air blown out from the plate-like nozzle heats the printed circuit board and then sucks in from the nearby suction port, so that it interferes with the hot air blown out from other plate-like nozzles. Gana,. Therefore, in the reflow furnace according to the present invention, the oxygen concentration free from turbulent flow in the pineapple is stabilized.

Brief Description of Drawings

[0032] [Fig. 1] Front sectional view of the reflow furnace of the present invention

[Figure 2] Front sectional view of hot air blowing heater installed in the reflow furnace of the present invention

[Fig. 3] Cross-sectional side view of hot air blowing heater installed in the reflow furnace of the present invention

[Fig. 4] Partial perspective view of hot air blowing heater installed in the reflow furnace of the present invention

[Figure 5] Plan view of Figure 4

[Figure 6] Partial enlarged view of Figure 2

Explanation of symbols

[0033] 1 Reflow furnace

3 Preheating zone

4 heating zones

5 Cooling zone 6 Hot air blowing heater

23 Heater surface

24 Plate nozzle

25 Outlet

26 Suction port

27 blocks

29 Locking device

30 balls

31 Compression panel

32 depression

Industrial applicability

The reflow furnace of the present invention has an excellent effect in an inert atmosphere reflow furnace in which the inside of the pineapple is filled with an inert gas because there is no turbulent flow of hot air, but because the entire printed circuit board can be heated uniformly. Needless to say, it can also be used in atmospheric reflow furnaces.

Claims

The scope of the claims

[1] In a reflow furnace that also has preheating zone, main heating zone, and cooling zone forces, zigzag plate-like nozzles that protrude from the heater surface force are printed on the printed circuit board at the top or top and bottom of the preheating zone and main heating zone A plurality of strips are arranged in a direction transverse to the direction of travel of the plate, and each plate nozzle is configured with a plurality of block forces, and each block is movable in the vertical direction. A reflow furnace characterized in that a suction port is formed in the vicinity of the nozzle.

2. The reflow furnace according to claim 1, wherein the block includes a plurality of sides forming a zigzag shape.

[3] The reflow furnace according to claim 1, wherein a locking plate is provided between the blocks so as to stop the blocks at appropriate positions.