JPH02112873A - Method and device for automatic soldering - Google Patents

Abstract

PURPOSE:To improve working efficiency by heating the rear surface of a circuit board transported at a high speed and soldering the circuit board while generating the flow in the direction approximately perpendicular to the transporting direction of the circuit board relatively between the circuit board and the molten solder ejected from nozzles. CONSTITUTION:The circuit board 2 is driven at a high speed of about 3m per minute in a direction A and arrives at the position of a fluxer 6 while the end 2b of the circuit board 2 is held by a chain conveyor 11 when the conveyor 11 is driven by a motor 12. Since a fluxer 6 is disposed to incline by about 45 deg. with the transporting direction of the circuit board 2, the flux coating of the efficiency substantially equally good as the efficiency of the fluxer 6 having an aperture 6a of about 1.4 times the aperture of the perpendicularly disposed fluxer. The circuit board 2 coated with the flux passes above an air curtain 8 and is subjected to heating at the curve milder than a prescribed temp. rising curve above a preheater 9. In addition, the circuit board 2 passes over the sufficiently long preheated 9 in such a manner that the rear surface 2a of the substrate attains about 110 deg.C at the time of arriving at the soldering both 10. Good soldering is thus executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method and apparatus for automatic soldering, and in particular, to conveying a board at a high speed of about 3 m/min or more, the soldering performance is lower than that of the conventional method. The present invention relates to an innovative method and apparatus for automatic soldering with extremely high productivity, which enables automatic soldering to be performed at a speed two to three times faster than conventional methods.

PRIOR ART Conventional automatic soldering methods and devices have been put into practical use that perform soldering by spouting molten solder from a nozzle that opens in a direction perpendicular to the direction in which the board is transported. However, in the soldering method and apparatus, as shown in FIGS. 6 and 7, when the molten solder 1 and the lower surface 2a of the substrate 2 are separated,
That is, when the solder breaks, the molten solder 1 gradually separates from the widthwise ends 2b of the substrate 2 toward the widthwise center 2c, and finally the separation is completed at the widthwise center 2c. Bridges, icicles, and bumps tend to occur in the central portion 2c, and it is difficult to completely prevent these.

In this type of soldering, the defective point 3 can only be detected by inspection after completion of automatic soldering and corrected manually, which requires a lot of man-hours for inspection and correction, reducing work efficiency. In addition, there was a drawback that the quality of the product deteriorated.

Furthermore, if the transport speed of the board 2 is increased to improve work efficiency, the time required for flux application using a fluxer, preheating using a preheater, and soldering using jet soldering may not be secured, resulting in a decrease in soldering performance. However, there was a drawback that soldering itself could not be performed at all, and that work efficiency could not be improved by increasing the conveyance speed of the board 2.

Another method is disclosed in Japanese Patent Publication No. 59-156568, in which the solder tank is arranged at an angle with respect to the conveying direction of the board 2, but this method also simply arranges the solder tank at an angle. Therefore, productivity cannot be significantly improved by increasing the substrate transport speed, and there is room for improvement in this respect.

Purpose The present invention has been made in order to eliminate the drawbacks of the prior art described above, and its purpose is to solder the board with the part facing down at a high speed of about 3 m/min or more. A substrate transfer device that transfers the substrate, a fluxer arranged at an angle of approximately 45'' to the transfer direction of the substrate, and the lower surface of the substrate that is transferred at high speed are preheated by gentle heating below a predetermined temperature rise curve. The board is equipped with a preheater having a length sufficient to heat the board to the desired temperature, and a solder tank equipped with a nozzle that spouts molten solder at an angle of approximately 45'' to the board transport direction, and the board is transported at the high speed mentioned above. Conventional soldering is achieved by sufficiently heating the bottom surface of the substrate and by creating a relative flow between the substrate and the molten solder spouted from the nozzle in a direction substantially perpendicular to the conveying direction of the substrate. is 2 to 3 times the speed (i.e., substrate transport speed) (3 m to 4.5 m per minute)
) to perform soldering at a high speed, greatly improving work efficiency. Another object is to prevent the molten solder from concentrating in the center of the board when the molten solder breaks, thereby achieving good soldering performance without bridging, icicles, or splatters.

Still another purpose is to form a flat part on the wave crest of the spouting molten solder, so that the molten solder remains at the required soldering points of the board being transported at high speed for the time necessary to ensure good soldering performance. The purpose is to make it possible to perform high-speed and good soldering by bringing the materials into contact with each other.

Configuration In short, the method of the present invention (claim 1) is to transport a substrate at a high speed of about 3 m per minute or more, and to arrange a fluxer and a jet soldering tank at an angle of approximately 456 degrees with respect to the direction of transport of the substrate. This increases the substantial flux application time and the contact time of molten solder to the points required for soldering of the board, thereby securing the processing time for the board transported at the high speed, and using a sufficiently long preheater to increase the contact time of the molten solder. This method is characterized in that soldering is performed at high speed by slowly heating the lower surface of the substrate being transported to a preheating temperature below a predetermined temperature rise curve.

Further, the apparatus of the present invention (claim 3) includes a substrate transport device that transports the board at a high speed of about 3 m/min or more with the required soldering part of the board facing downward, and a board that is tilted approximately 456 degrees with respect to the transport direction of the board. A fluxer and a jet soldering bath are provided, and the lower surface of the substrate being transported at a high speed between the fluxer and the jet soldering bath is heated to a preheating temperature by a temperature equal to or less than a predetermined temperature rise curve. It is characterized by having a preheater with a length of

The present invention will be explained below based on embodiments shown in the drawings. 1st
Referring to the drawings and FIG. 2, an automatic soldering device 4 according to the present invention includes a substrate transfer device 5, a fluxer 6, a preheater 9, and a solder bath 10.

The substrate transport device 5 is for transporting the substrate 2 in the direction of arrow A at a speed two to three times faster than the conventional speed, that is, at a high speed of about 3 m/min or more, and includes two sets of chain conveyors 1.
1 are arranged in parallel.

The chain conveyor 11 is connected to a motor 12 via a belt 13, and as the motor 12 rotates, a shaft 14
It is driven by a sprocket (not shown) that rotates around the .

The fluxer 6 is disposed below the board 2 to be transported, and pre-treats (flux coats) the soldering points 2d of the board 2 so that the solder adheres well. It is arranged at an angle of approximately 45'' with respect to the direction of arrow A).

Particularly, in the automatic soldering apparatus 4 of the present invention, two openings 6a of fluxers are provided in parallel so that the substrate 2 transported at high speed can be sufficiently pretreated.

The air curtain 8 blows out compressed air from a nozzle 8a to separate the fluxer 6 and the preheater 9, and the nozzle 8a is arranged at an angle of about 45 degrees with respect to the conveyance direction of the substrate 2.

The preheater 9 heats the lower surface 2a of the substrate 2 to a predetermined temperature.
Since the substrate 2 is transported at high speed, it is arranged over a length two to three times that of a normal one, specifically about 2 m, and the front end 9 of the preheater 9 in the transport direction of the substrate 2 is provided.
By configuring the length of the heater to be gradually longer at point a and gradually shorter at the rear end portion 9b,
Heating starts and ends at a position of the air curtain 8 and the solder tank 10 that are substantially parallel to the primary solder tank 16.

The solder tank 10 consists of a primary solder tank 16 and a secondary solder tank 18. Both solder tanks 16 and 18 store molten solder 1 melted by a heater (not shown), and a motor 19 and a belt 20.
The molten solder 1 is ejected from each nozzle 21 and 22 by an impeller (not shown) driven by an impeller (not shown). Nozzles 21 of the primary solder tank 16 and the secondary solder tank 18
and 22 are arranged at an angle of about 45'' with respect to the conveyance direction of the substrate 2, and a guide plate 23 for the molten solder 1 is arranged above the nozzle 22 of the secondary solder tank 18, and a guide plate 23 for the molten solder 1 is provided to guide the molten solder 1 from the nozzle 22. The wave crest 1a of the ejected molten solder 1 forms a flat portion 24.

Further, the automatic soldering device 4 is provided with a known substrate cooling fan 25 and an exhaust duct 26 at predetermined positions.

The method according to the present invention (claim 1) transports the substrate 2 at a high speed of about 3 m per minute or more, and the transport direction of the substrate 2 (
By arranging the fluxer 6 and the jet soldering bath 10 at an angle of approximately 45 degrees with respect to the direction of arrow A, the required soldering of the board 2 can be done in a timely manner that requires substantially less flux application time and molten solder l. The contact time is increased to secure the processing time for the substrate 2 transported at high speed, and the temperature of the lower surface 2a of the substrate 2 transported at high speed is increased to the preheating temperature by a sufficiently long preheater 9 to a predetermined temperature rise curve. This method performs high-speed soldering by heating slowly below.

Function The present invention is constructed as described above, and its function will be explained below. In FIGS. 1 and 2, the solder in the solder baths 16 and 18 is heated and melted by energizing a heater (not shown). When the motor 19 is powered on and rotates, an impeller (not shown) is driven to rotate via the belt 20, and the molten solder l in the primary solder tank 16 and the secondary solder tank 18 is It is ejected upward from nozzles 21,22. The molten solder 1 ejected from the nozzle 22 is guided by the guide plate 23 and flows left and right, so that a flat portion 24 is formed at the wave crest 1a.

On the other hand, when the chain conveyor 11 is driven by the motor 12, the substrate 2 is moved at a high speed of 3 m to 4.5 m per minute in the direction of the arrow while the end portion 2b is held by the chain conveyor 11, and the substrate 2 is moved to the position of the fluxer 6. reach. Since the fluxer 6 is disposed at an angle of approximately 45 inches with respect to the conveyance direction of the substrate 2, the fluxer 6 has an opening 6a having the same rectangular width as compared to a known fluxer disposed perpendicular to the conveyance direction of the substrate 2. 6, it is substantially the same as that of the fluxer 6 having an opening 6a that is approximately 1.4 times (ρ- times) larger, and it is possible to perform flux application with high efficiency.Furthermore, the automatic soldering of the present invention In the apparatus 1, the conventional substrate transport speed is 1/min.
．． In order to perform soldering at a high speed of 2 to 3 times 5m, that is, 3m to 4.5m per minute, two openings 6a for applying flux are arranged in the manual direction, so that the flux application on the board 2 is faster. Processing can be carried out adequately.

The substrate 2 treated with the fluxer 6 passes over the air curtain 8 and is conveyed above the preheater 9, while the lower surface 2a of the substrate 2 is heated to about 110'', but when heated rapidly, only the lower surface 2a of the substrate is heated. becomes high temperature, leaving other parts at a low temperature, causing warping of the board 20, deterioration of soldering performance, and in extreme cases, damage to the board 2 due to heat shock.
Since pattern cutting or damage to the substrate 2 may occur, heating is performed more slowly than a predetermined temperature rise curve that does not cause such problems, and the bottom surface 2a of the substrate is heated at approximately 110 degrees when it reaches the solder bath 10. The substrate 2 passes over a sufficiently long preheater 9. Particularly, in the automatic soldering of the present invention, since the substrate 2 is transported in the device 4 at a high speed two to three times as high as the conventional transport speed, the length of the preheater 9 is approximately 2 m or more.

The front end 9a of the preheater 9 is formed approximately 45'' with respect to the conveying direction of the substrate 2 (parallel to the air curtain 8), and the heating start position of the substrate 2 is set at an equal distance after passing through the air curtain 8. Then, the substrate 2, which is gently heated while being conveyed over a long preheater 9 and whose lower surface 2a reaches a temperature of approximately 110°C, reaches the solder bath 10, where it is soldered by the molten solder 1 spouted from the nozzles 21 and 22. will be attached.

In order to maintain good soldering performance, it has been confirmed through many experiments that the contact time between the molten solder 1 and the required soldering point 2d of the board 2 is approximately 3 seconds for the best results. Therefore, in order to maintain a contact time of approximately 3 seconds with the substrate 2 being transported at a speed two to three times faster than the conventional method, the solder bath IO is arranged at an angle of about 45 degrees with respect to the transport direction. The contact length is about 1.4 times as long as the fluxer 6 described above, and the two nozzles and 21.22 are arranged in parallel, and the wave crest 1a of the jet of the nozzle 22 has a flat part 24. This ensures a contact time of 3 seconds with the substrate 2.

Further, another effect of arranging the solder bath 10 at an angle of about 456 with respect to the conveying direction of the substrate 2 is that the molten solder 1 spouted from the nozzles 21 and 22 is This flow results in soldering while producing a flow distributed in a direction substantially perpendicular to the conveying direction (direction of arrow A) and a direction (direction of arrow B) relative to the substrate 2. At this time, the solder breakage is caused by the flow of molten solder 1 in the direction of arrow B in FIG. finish. This prevents the molten solder 1 from concentrating on one point on the board 2 when the solder breaks, and it is also possible to prevent soldering defects such as bridges, icicles, and bumps from occurring.

Further, the rear end portion 9b of the preheater 9 is formed approximately parallel to the solder bath 10 and at an angle of approximately 45 degrees with respect to the conveying direction of the substrate 2. Since it is equal in each part, soldering can be performed under exactly the same conditions over the entire surface of the board 2 (there is no variation in temperature in each part of the board 2), and the soldering performance can be made uniform.

Effects As described above, the present invention provides a substrate transport device that transports the board at a high speed of approximately 3 m/min or more with the soldering point of the board facing down, and a board that is tilted approximately 45 degrees with respect to the transport direction of the board. a preheater having a length sufficient to heat the lower surface of a substrate being transported at high speed to a preheating temperature by heating below a predetermined temperature rise curve; Equipped with a solder tank equipped with a nozzle that spouts molten solder at an angle of 100°, the bottom surface of the board being transported at high speed is sufficiently heated, and the space between the board and the molten solder is relative to the board transport direction. Since soldering is performed while generating a flow in a substantially perpendicular direction, the board can be transported and soldered at a high speed of 3 m to 4.5 m per minute, that is, 2 to 3 times faster than conventional methods.
This has the effect of significantly improving productivity. In addition, it is possible to prevent molten solder from concentrating on the center of the board when the solder breaks, and it is possible to perform good soldering without bridging, icicles, bumps, etc. Furthermore, since a flat portion is formed at the crest of the wave of molten solder ejected from the nozzle, sufficient contact time between the wave crest of the molten solder and the board being transported at high speed is ensured, and the soldering performance is good at high speed. This has the effect of enabling smooth soldering.

[Brief explanation of drawings]

Figures 1 to 5 relate to the present invention; Figure 1 is a plan view of the automatic soldering device showing the entire device, Figure 2 is a front view of the automatic soldering device showing the entire device, and Figure 3 is the soldering device. Figure 4 is a perspective view of the main parts to explain the transfer state of the nozzle of the tank and the board, Figure 4 is a plan view of the main part to explain the flow state of molten solder to the board, and Figure 5 shows the points where soldering is required in the soldering state. 6 and 7 are related to the conventional example, FIG. 6 is a plan view showing a state in which a bridge is formed at the center of the bottom surface of the board, and FIG. 7 is a schematic diagram showing the state of flow of molten solder. FIG. 3 is a schematic diagram showing a flow state of molten solder such that a bridge is formed in the center. 1a is the wave front of the jet flow, 2 is the substrate, 2a is the bottom surface, 2d is the location where soldering is required, 4 is the automatic soldering device, 5 is the substrate transfer device, 6 is the fluxer, 6a is the nozzle, 9 is the preheater, 10
2 is the jet soldering tank, 21 is the nozzle of the primary soldering tank, and 22 is the 2
The nozzle 24 of the next solder bath is a flat part of the jet. Figure ＼ ＼ Figure Figure

Claims (1)

[Claims] 1. The substrate is transported at a high speed of about 3 m/min or more, and a fluxer and a jet soldering tank are arranged at an angle of about 45 degrees with respect to the direction of transport of the board. The substantial flux application time and the contact time of molten solder in contact with the soldering points are increased to secure the processing time for the board transported at high speed, and a sufficiently long preheater is used to increase the contact time of the molten solder to the board transported at high speed. An automatic soldering method characterized by soldering at high speed by slowly heating the lower surface to a preheating temperature below a predetermined temperature rise curve. 2. The automatic soldering method according to claim 1, wherein the substrate conveyance speed is 3 m to 4.5 m per minute. 3. A board transport device that transports the board at a high speed of approximately 3 m/min or more with the soldering point facing downward, and a fluxer and a jet-type soldering tank arranged at an angle of approximately 45 degrees with respect to the board transport direction. , a preheater having a length sufficient to heat the lower surface of the substrate transported at high speed to a preheating temperature by heating the lower surface of the substrate transported at a high speed to a preheating temperature below a predetermined temperature rise curve, between the fluxer and the jet soldering bath. An automatic soldering device characterized by: 4. The automatic soldering apparatus according to claim 3, wherein the wave crest of the jet of the jet soldering bath has a flat portion. 5. The automatic soldering apparatus according to claim 3, wherein the fluxer and the jet soldering bath each have two nozzles arranged close to each other in parallel.