JP2002314237A - Soldering equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that, after a printed wiring board is conveyed at an angle of elevation by a conveying means while heated, when it is soldered by coming into contact with a jet wave of a fused solder, this conveying means is covered with a tunnel-like chamber in order to have better solder wettability, and the inert gas atmosphere is formed, and the board is conveyed in from a convey-in port of one end and conveyed out from the convey-out port of the other end, and at this time, the high-temperature inert gas atmosphere is leaked out from the convey-out port of the tunnel-like chamber. SOLUTION: An opening (convey-out port) 18 is provided on a face of a downward side at the other end of a tunnel-like chamber 16, and a printed wiring board 1 is conveyed out by a convey-out conveyor 17, thereby preventing a leakage of the inactive gas atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering apparatus for performing soldering by bringing a plate-like work to be soldered such as a printed wiring board on which electronic components are mounted into contact with a jet wave of molten solder.

[0002] An inert gas such as nitrogen gas is supplied into a chamber to form an inert gas atmosphere having a low oxygen concentration, and soldering of a printed wiring board is performed in this atmosphere. That is, it is because the soldered portion of the printed wiring board and the molten solder can be prevented from being oxidized, and soldering with excellent wettability can be performed.

[0003] In such a soldering apparatus, it is desired that the flow rate of an inert gas consumed per unit time to obtain a target oxygen concentration be small. That is, it is for reducing the production cost.

[0004]

2. Description of the Related Art A conventional soldering apparatus will be described with reference to FIG. FIG. 3 is a view showing a conventional soldering apparatus. FIG. 3A is a side sectional view of the soldering apparatus, and FIG.
FIG. 2 is a plan view of a conveyor. In FIG. 3B, the tunnel-shaped chamber is indicated by a broken line for easy understanding.

That is, the both ends of the printed wiring board 1 are held by the holding claws 3 of the conveyor 30 and the arrow A
After the pre-heating of the printed wiring board 1 by the heater 4 in the pre-heating step 5, the lower surface of the printed wiring board 1, that is, In this configuration, the soldering surface 1a is brought into contact with the jet wave 8 of the molten solder 7 to perform soldering.

The elevation angle θ for transporting the printed wiring board 1 is usually selected in the range of about 2 to 10 °, and within this range, the range of 3 to 5 ° is most often used. As described above, the reason why the printed wiring board 1 is brought into contact with the jet wave 8 of the molten solder 7 while being conveyed at an elevation angle along the board surface is that the separation angle between the printed wiring board 1 and the jet wave 8 of the molten solder 7 is large. In addition, by applying oblique gravity to the board surface of the printed wiring board 1, a solder bridge defect which is likely to occur between adjacent soldered portions formed on the printed wiring board 1 is eliminated. This is because the fillet shape can be further adjusted.

The conveyor 30 provided at the elevation angle θ
Are formed in two parallel lines, and are provided with a holding claw 3 for holding a side end of the printed wiring board 1 on a transport chain 10 that rotates and runs along a linear conveyor frame 9. As the heater 4 in the preheating step 5, an infrared heating means such as a sheathed heater or a panel heater is often used, but a hot air heating means or a combination of these heating means may be used. The molten solder 7 that is heated and melted by a heater (not shown) is accommodated in the solder bath 11,
The molten solder 7 is supplied to a blowing body 14 by a pump 12 and jetted from the blowing port 15 to form a jet wave 8.

A tunnel-shaped chamber 16 is provided along the conveyor 30 provided at the elevation angle θ,
At one end, an opening (that is, an entrance) 26 for carrying the printed wiring board 1 and at the other end, an opening (that is, an exit) 31 that unloads the printed wiring board 1 are provided. In the tunnel-shaped chamber 16, a restraining plate 21 is provided in a direction orthogonal to the transport direction of the printed wiring board 1, and constitutes a labyrinth seal for suppressing unnecessary atmosphere flow generated in the tunnel-shaped chamber 16. ing.

The heater 4 in the preheating step 5 is accommodated in the tunnel-shaped chamber 16. However, in the soldering step 6, only the jet 8 of the molten solder 7 is exposed in the tunnel-shaped chamber 16. An opening 23 provided with a skirt portion 22 is provided. The skirt 22 can be completely sealed by immersing it in the molten solder 7 of the solder bath 11.

[0010] The nitrogen gas 25 is supplied from the gas supply port housing 24 such as a nozzle or a horn to the soldering step 6, and the oxygen concentration in the soldering step 6, which has the greatest effect on the soldering quality, becomes the lowest. Is taken into account.

[0011]

However, in such a soldering apparatus, since a heater serving as a heating source and a jet wave of molten solder are present in the tunnel-shaped chamber, an atmosphere heated in the tunnel-shaped chamber is not provided. The upward movement of the atmosphere promotes the leakage of the atmosphere (arrow B) from the outlet of the tunnel-shaped chamber. That is, the tunnel-like chamber acts like a chimney, and positive air leakage occurs in the direction of arrow B from the carry-out port, and positive air entry occurs in the direction of arrow C from the carry-in port. This cannot be completely prevented even if a large number of restraining plates are provided.

Therefore, there has been a problem that the nitrogen gas supply flow rate per unit time required to maintain the oxygen concentration in the tunnel-shaped chamber at the target oxygen concentration is increased.

In addition, unnecessary atmospheric flow in the tunnel-shaped chamber also causes unstable fluctuation of the oxygen concentration in the tunnel-shaped chamber, whereby the solder wettability of the printed wiring board fluctuates unstable. In addition, there is a problem that the soldering quality of the printed wiring board fluctuates unstable.

Further, since the atmosphere in the tunnel-shaped chamber leaks only from the carry-out port, the atmosphere enters from the carry-in port,
There is a problem that the oxygen concentration in the pre-heating step is several times higher than the oxygen concentration in the soldering step, and this causes the soldered portion of the printed wiring board to be easily oxidized in the pre-heating step, which hinders its solderability. Was a factor.

In order to avoid such a difficult problem, there is a soldering apparatus in which the printed wiring board is transported horizontally and a tunnel-like chamber is provided horizontally in accordance with this. It cannot solve the problems that solder bridge defects are likely to occur between matching soldered portions and that the fillet shape of the soldered portion is likely to be unstable.

An object of the present invention is to suppress the leakage of the atmosphere in such a tunnel-like chamber, suppress the intrusion of the atmosphere into the tunnel-like chamber, and reduce the amount of inert gas such as nitrogen gas per unit time. It is an object of the present invention to realize a soldering apparatus capable of reducing a supply flow rate so that a high-quality printed wiring board can be stably produced at low cost.

[0017]

The soldering apparatus according to the present invention is characterized in that a carry-out port and a carry-in port are provided so that the atmosphere in a tunnel-shaped chamber provided at an elevation angle is hardly leaked. (1) A heater for performing preheating, a solder bath for forming a jet flow of molten solder, a conveying means for conveying a plate-like work to be soldered at an elevation angle, and an inclination inclined to the conveyance direction of the conveyance means. And a tunnel-shaped chamber that covers the transfer means, and preheats the work to be soldered with the heater in an inert gas atmosphere, and then contacts the jet wave of the molten solder to perform soldering. In a soldering apparatus, it is constituted as follows.

That is, the tunnel-shaped chamber has a lower surface having an opening for carrying out a plate-shaped work to be soldered that has come into contact with the jet wave.

As a result, even in a tunnel-shaped chamber provided at an elevation angle, the atmosphere whose temperature is increased by heating is easily accumulated in the upper space, and the leakage of the atmosphere in the tunnel-shaped chamber is suppressed. This also suppresses the ingress of air. As a result, the supply flow rate of the inert gas per unit time required to obtain the target oxygen concentration can be reduced, the oxygen concentration is stabilized, and the oxygen concentration in the preheating step is also reduced. Will be able to (2) A heater for preheating, a solder bath for forming a jet wave of molten solder, a conveying means for conveying the plate-like work to be soldered at an elevation angle, and an inclination inclined to the conveyance direction of the conveyance means. And a tunnel-shaped chamber that covers the transfer means, and preheats the work to be soldered with the heater in an inert gas atmosphere, and then contacts the jet wave of the molten solder to perform soldering. In a soldering apparatus, it is constituted as follows.

That is, the tunnel-like chamber has a plate-like soldering work which has been brought into contact with the opening for carrying the plate-like soldering work into the tunnel-like chamber on the lower surface and the jet wave. And an opening for carrying out.

As a result, even in a tunnel-shaped chamber provided at an elevation angle, the atmosphere whose temperature has been raised by heating is more likely to accumulate in the upper space, and the leakage of the atmosphere in the tunnel-shaped chamber is further suppressed. You. In addition, the entry of the atmosphere is further suppressed. As a result, the supply flow rate of the inert gas per unit time required for obtaining the target oxygen concentration can be further reduced, the oxygen concentration is further stabilized, and the oxygen concentration in the preheating step is increased. Can be further reduced.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The soldering apparatus of the present invention can be realized in the following embodiments. (1) First Embodiment A first embodiment of a soldering apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a view for explaining a soldering apparatus according to a first embodiment. FIG. 1A is a side sectional view of the soldering apparatus, and FIG. 1B is a plan view of a transport conveyor. In FIG. 1B, the tunnel-shaped chamber is indicated by a broken line for easy understanding. The description given in FIG. 3 is appropriately omitted.

That is, similar to the conventional soldering apparatus illustrated in FIG. 3, the main conveyor 2 provided at an elevation angle θ
A pre-heating step 5 and a soldering step 6 are provided in the tunnel-shaped chamber 16.

However, in the soldering apparatus of the first embodiment, unlike the conventional opening (unloading port) 31 shown in FIG.
An opening 18 is provided on the bottom surface of the printed wiring board 6, and the opening 18 is used as a carry-out port of the printed wiring board 1 after soldering, that is, after the soldering process 6. Therefore, an unloading conveyor 17 for unloading the printed wiring board 1 after the soldering process 6 is provided.

The unloading conveyor 17 receives the printed wiring board 1 transported by the main transport conveyor 2 provided at an elevation angle θ, and the bottom of a tunnel-shaped chamber 16 provided at an elevation angle along the main transport conveyor 2. Is lowered through an opening (unloading port) 18 provided at
The main conveyor 2 is used to form a transfer conveyor, which is a two-parallel placement type conveyor. The other configuration of the main conveyor 2 is the same as that of the conventional conveyor 30 shown in FIG.

As a result, the atmosphere which is heated by the heater 4 in the preheating step 5, the molten solder 7 in the soldering step 6 and its jet wave 8 and is going to rise is less likely to leak out of the tunnel-shaped chamber 16, so that the tunnel-shaped It is easy to accumulate in the chamber 18. That is, a low oxygen concentration inert gas atmosphere is formed in the tunnel-shaped chamber 16 by the nitrogen gas 25 supplied from the gas supply port housing 24, and the low oxygen concentration inert gas atmosphere is formed in the tunnel-shaped chamber 16. It will stay stable.

Therefore, it is possible to reduce the nitrogen gas supply flow rate per unit time required to obtain a target oxygen concentration. Further, since the atmosphere in the tunnel-shaped chamber 16 is hardly leaked, the fluctuation of the oxygen concentration in the tunnel-shaped chamber 16 is small, and
A stable oxygen concentration can be obtained. In addition, the oxygen concentration in the preheating step 5 can be made as low as the oxygen concentration in the soldering step 6. Therefore, the soldering quality, especially the wettability of the printed wiring board 1 is also improved, and the wettability is stabilized.

As a result, the printed wiring board 1 is transported at an elevation angle to form a regular fillet shape without occurrence of a solder bridge defect and the like, and high quality soldering with excellent wettability is performed stably. Can be achieved at the same time, and this can be achieved at a low cost. (2) Second Embodiment With reference to FIG. 2, a second embodiment of the device to be soldered according to the present invention will be described. 2A and 2B are views for explaining the soldering apparatus of the embodiment-2, FIG. 2A is a side sectional view of the soldering apparatus, and FIG. 2B is a plan view of a transport conveyor. In FIG. 2B, the tunnel-shaped chamber is indicated by a broken line for easy understanding.
The description of the reference numerals shown in FIG. 1 is appropriately omitted.

In the embodiment example 2, the printed wiring board 1
Not only when unloading from the tunnel-shaped chamber 16,
When the printed wiring board 1 is loaded into the tunnel-shaped chamber 16, the printed wiring board 1 is loaded from the bottom of the tunnel-shaped chamber 16. Therefore, a carry-in conveyor 19 is provided.

That is, in order to transfer the printed wiring board 1 to the main transport conveyor 2 provided at the elevation angle θ, a parallel two-row mounting type conveyor is provided as the carry-in conveyor 19, and the main transport conveyor 2 and the carry-out conveyor 19 are provided. 17 together with the conveyor. This loading conveyor 19
Differs from the opening (transport) 26 shown in FIG. 1 in that the printed wiring board 1 is ascended and conveyed through an opening (transport) 20 provided on the bottom surface of the tunnel-shaped chamber 16 provided at an elevation angle, and thereafter the main transport conveyor 2 is configured to be conveyed in the elevation angle conveyance direction. The other configuration of the conveyor 2 is the same as that of the main conveyor 2 shown in FIG.

With this configuration, the heater 4 in the preheating step 5, the molten solder 7 in the soldering step 6, and the atmosphere which is heated by the jet wave 8 and rises are leaked from the tunnel-shaped chamber 16. In addition, the atmosphere becomes difficult to enter into the tunnel-shaped chamber 16 and the atmosphere in the tunnel-shaped chamber 16 can be more easily accumulated.

That is, an inert gas atmosphere having a low oxygen concentration is formed in the tunnel-shaped chamber 16 by the nitrogen gas 25 supplied from the gas supply port housing 24. Chamber 16
To stay within. In general, the function of promoting exhaust from the chimney is caused by the promotion of heat convection. However, the provision of the opening (port) 20 and the opening (port) 18 on the bottom surface of the tunnel-shaped chamber 16 eliminates the promotion of exhaust, and the The tunnel-shaped chamber 16 acts like a balloon of a hot air balloon.
An inert gas atmosphere having a low oxygen concentration can be stored and held therein.

Accordingly, the nitrogen gas supply flow rate per unit time required to obtain a desired oxygen concentration can be further reduced as compared with the soldering apparatus shown in the embodiment-1. Become. Further, the fluctuation of the oxygen concentration in the tunnel-shaped chamber 16 is further reduced, and an extremely stable oxygen concentration can be obtained. The oxygen concentration in the preheating step 5 is also substantially equal to the oxygen concentration in the soldering step 6. Low oxygen concentration can be maintained. Therefore, the soldering quality, especially wettability, of the printed wiring board 1 is also improved and stabilized.

As a result, the printed wiring board 1 is conveyed at an elevation angle to form a uniform fillet shape without occurrence of solder bridge defects, and stable and high quality soldering with excellent wettability. Can be achieved in a higher dimension, and can be achieved at a lower cost.

[0035]

As described above, according to the soldering apparatus of the present invention, a plate-like work to be soldered, that is, a printed wiring board is transported at an elevation angle and soldering is performed in a tunnel-like chamber provided at the elevation angle. Even under the condition of work, it is possible to obtain a target inert gas atmosphere having a low oxygen concentration while reducing a supply flow rate of an inert gas such as a nitrogen gas per unit time. In addition, the oxygen concentration in the preheating step can be set to the same value as the oxygen concentration in the soldering step, and the fluctuation of the oxygen concentration in each of these steps can be reduced.

Accordingly, oxidation of the plate-shaped work to be soldered, that is, the soldered portion of the printed wiring board and the molten solder can be stably prevented at low cost, and the wettability is excellent at low cost. The stable soldering work can be performed. of course,
Since the printed wiring board is conveyed at an elevation angle as in the related art, no solder bridge failure occurs between adjacent soldered portions, and the fillet shape of the soldered portion is uniform and uniform.

As a result, a solder bridge defect does not occur, the fillet shape of the portion to be soldered is uniform and uniform, and a printed wiring board having excellent solder wettability and stable quality can be produced.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a soldering apparatus according to a first embodiment.

FIG. 2 is a diagram for explaining a soldering apparatus according to a second embodiment;

FIG. 3 is a view showing a conventional soldering apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed wiring board 1a Surface to be soldered 2 Main conveyor 3 Holding claw 4 Heater 5 Preheating step 6 Soldering step 7 Melted solder 8 Jet wave 9 Conveyor frame 10 Transport chain 11 Solder tank 12 Pump 14 Spout body 15 Spout DESCRIPTION OF SYMBOLS 16 Tunnel-like chamber 17 Conveyor for unloading 18 Opening (exit port) 19 Conveyor for import 20 Opening (for importing) 21 Suppression plate 22 Skirt part 23 Opening 24 Gas supply port case 25 Nitrogen gas 26 Opening (Inlet)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 31/02 310 B23K 31/02 310B 310H

Claims (2)

[Claims] 1. A heater for performing preheating, a solder bath for forming a jet wave of molten solder, a conveying means for conveying a plate-like work to be soldered at an elevation angle, and an elevation angle in a conveying direction of the conveyance means. A tunnel-shaped chamber that is provided at an angle and covers the transporting means. After the workpiece to be soldered is preheated by the heater in an inert gas atmosphere, the workpiece is brought into contact with the jet wave of the molten solder to form a solder. In the soldering apparatus for soldering, the tunnel-shaped chamber has an opening for discharging a plate-shaped work to be soldered which has been brought into contact with the jet wave on a lower surface. 2. A heater for performing preheating, a solder bath for forming a jet wave of molten solder, a conveying means for conveying a plate-like work to be soldered at an elevation angle, and an elevation angle in a conveying direction of the conveyance means. A tunnel-shaped chamber that is provided at an angle and covers the transporting means. After the workpiece to be soldered is preheated by the heater in an inert gas atmosphere, the workpiece is brought into contact with the jet wave of the molten solder to form a solder. In the soldering apparatus for mounting, the tunnel-shaped chamber has a plate-shaped cover that has been brought into contact with the jet wave and an opening for carrying the plate-shaped work to be soldered into the tunnel-shaped chamber on a lower surface. An opening for carrying out a soldering work.