JPH10215063A - Reflow soldering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease falling of solder by mounting a part on the opposite side on a board, with the surface of the board on which cream solder is applied down, carrying the substrate in the slant attitude while heating the board, melting the cream solder and performing soldering. SOLUTION: After cream solder 11 is applied on the surface of a circuit board 10, a chip part 12 is mounted. The surface of the circuit board 10, on which such a chip part 12 is mounted, is directed downward, and the board is introduced into a reflow furnace. In this reflow furnace, a conveyer 50 and a heater 51 are arranged in the inclined attitude. The circuit board 10, which is introduced into the reflow furnace by the conveyer 50, is carried toward the cooling zone side from the preheating zone side. At this time, preheating or heating for the reflow is performed with the heater 51. The powder of the solder in the cream solder 11 is melted, and the soldering is performed. Thus, the falling amount of the solder can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow soldering apparatus and, more particularly, to a reflow soldering apparatus in which soldering is performed while heating a surface of a substrate on which a cream solder is applied to face down.

[0002]

2. Description of the Related Art Electronic circuits are manufactured by mounting electronic components on a circuit board made of an insulating material and soldering electrodes or leads of the electronic components to connection patterns on the circuit board. ing. The surface-mounted chip components are mounted on the same surface of the circuit board on which the cream solder is applied, and the surface of the circuit board on which the cream solder is applied and the chip components are mounted faces upward in a reflow furnace. Will be introduced. When heated in a reflow furnace, the solder powder in the cream solder melts, and the electrodes of the chip component are connected to the connection lands to perform soldering.

On the other hand, when an electronic component having leads is soldered in a reflow furnace, the circuit board is turned over while cream solder is applied on the circuit board, and a component with leads is mounted on the opposite surface. Is mounted, and its leads are made to penetrate the circuit board and protrude from the portion where the solder is applied. In such a state, when the solder-coated surface is placed in the reflow furnace with the surface facing down and heated, the solder of the powder in the cream solder melts and the leads are connected to the connection lands. Become.

FIGS. 13 and 14 show a reflow furnace used in such a process. This reflow furnace is composed of four zones of preheat zones 1 and 2, reflow zone 3 and cooling zone 4. ing. A conveyor 5 is arranged so as to move the circuit board in these zones 1 to 4 in that order. A heater 6 is disposed below the conveyor 5 to heat a circuit board conveyed by the conveyor 5 from below. A feature of such a reflow furnace is that the circuit board is heated while being conveyed by the conveyor 5 in a horizontal state, and reflow is performed.

[0005]

When the components with leads are soldered in a reflow furnace as described above, the surface of the circuit board on which the components are mounted is the upper side, and the surface on which the cream solder is applied is the lower side. It passes through the inside of the reflow furnace in a horizontal posture such that the soldering is performed by the heat at that time.

[0006] Since the soldering is performed in such a manner that the surface of the circuit board on which the cream solder is applied is directed straight downward, the heating reduces the viscosity of the cream solder and melts the solder. The molten solder will fall. In particular, compared to the case of soldering chip components, in the case of components with leads, since the amount of applied cream solder is large, the solder is likely to fall.

When the solder drops in the reflow process, it is necessary to clean the inside of the reflow furnace or to repair unsoldered portions of the circuit board after the reflow. Man-hours increase. In addition, since the solder falls, the amount of effectively used solder is reduced by that amount, and waste of the solder occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in particular, in a reflow apparatus that performs soldering while heating a surface on which a cream solder is applied to a lower side, a method for preventing solder from falling. It is an object of the present invention to provide a reflow soldering apparatus which is reduced.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a cream solder is applied on a substrate, a component is mounted on an opposite surface of the substrate, and the surface of the substrate on which the cream solder is applied is lowered. A reflow soldering apparatus, wherein the substrate is transported in an oblique posture, wherein the substrate is transported while being heated toward the side and the solder is melted and soldered. It is.

[0010] The substrate may be inclined in a direction perpendicular to a direction of conveyance by the conveying means and in a width direction of the conveying means. Further, the substrate may be inclined at an angle of 90 ° or less with respect to the horizontal direction.

[0011] A heater for heating the substrate may be provided below the transfer means, and the heater may be arranged in an oblique posture so as to be substantially parallel to the substrate to be transferred obliquely.

[0012]

1 to 9 show a process of manufacturing an electronic circuit device manufactured by a reflow soldering apparatus according to the present embodiment. Such a manufacturing process will be described later with reference to the drawings.

As shown in FIG. 1, a circuit board 10 made of an insulating material is prepared. Note that a wiring pattern and a connection land formed by etching a copper foil are formed on the circuit board 10 in advance. The cream solder 1 is formed on the surface of the circuit board 10 by screen printing.
1 is applied.

After the cream solder 11 is applied, a chip component 12 is mounted on the circuit board 10 by a mounting machine as shown in FIG. At this time, the positioning is performed so that the electrode portions on both sides of the chip component 12 correspond to the cream solder 11. Then, the circuit board 10 on which the chip components 12 are mounted is gently introduced into a reflow furnace, and the solder powder in the cream solder 11 is melted by heating in the furnace. The solder 13 is soldered to the connection lands on the circuit board 10 (see FIG. 3).

Thereafter, as shown in FIG. 4, a cream solder 17 for soldering a component with a lead is applied on the circuit board 10. Such a cream solder 17
Is applied by a coating apparatus shown in FIG. The details of such a coating apparatus will be described later.

After the cream solder 17 is applied, the circuit board 10 is turned upside down as shown in FIG. Thereafter, the leaded component 18 is mounted on the circuit board 10 by a mounting machine or manually.
Mount on top. FIG. 6 shows an air-core coil as an example of the component 18 with leads. At this time, the components 18 with leads are mounted on the upper surface of the circuit board 10, and the leads 19 are mounted so as to penetrate the circuit board 10. Then, the lead 19 of the leaded component 18
Will pass through the cream solder 17 which has been applied in advance.

When the electronic circuit is a high-frequency circuit, for example, as shown in FIG.
Mount on top At this time, the claw portion 21 protruding from the lower end side of the shield case 20 penetrates the through hole of the circuit board 10 and contacts the cream solder 17 on the lower surface of the circuit board 10.

In such a state, the circuit board 10 is gently introduced into a reflow furnace to be described later, as shown in FIGS. 11 and 12. Then, the solder powder in the cream solder 17 is melted in the reflow furnace, and the leads 19 of the leaded component 18 are solder 22
Is soldered to the connection lands of the circuit board 10. Further, the claws 21 of the shield case 20 are soldered to the connection lands of the circuit board 10 by solder 22 (see FIG. 8).

After the soldering is performed in the reflow furnace in this manner, unnecessary portions of the peripheral portion of the circuit board 10 protruding outside the shield case 20 are cut off and removed. Thereafter, a cover plate is attached so as to cover the upper opening of the shield case 20. Further, if necessary, the bottom plate of the shield case 20 is attached to the circuit board 1.
The circuit board 1 is mounted by mounting from the side opposite to
The circuit on 0 is formed in a state surrounded by the shield case 20.

Next, an apparatus for applying the cream solder 17 for soldering the leaded component 18 will be described with reference to FIG. The apparatus includes a frame 25, and a conveyor belt 26 is arranged on the frame 25 substantially horizontally. Further, a substrate backup plate 27 is disposed below the conveyor belt 26. Further, a board stopper 28 is mounted to be able to move up and down so as to cross the transfer path of the circuit board 10 transferred by the transfer belt 26.

A mask plate 30 is disposed above the conveyor belt 26. The mask plate 30 has a hollow nozzle 31 at a position where the cream solder 17 is applied. Squeegee guides 32 are mounted on both sides of the upper portion of the mask plate 30, and a pair of elevating cylinders 35 and 36 are movably supported by the squeegee guides 32 via a support 33. Squeegees 37 and 38 are attached to the tips of the rods of the lifting cylinders 35 and 36, respectively.

The circuit board 10 is transported leftward by the transport belt 26. Then, the transport of the circuit board 10 is stopped by the board stopper 28 waiting at the ascending position. Substantially in synchronization with this operation, the board backup plate 27 moves up, and moves the circuit board 10 upward from the transport belt 26. The rising position of the circuit board 10 is such that the tip of the hollow nozzle 31 of the mask plate 30 is
At a predetermined distance from the surface of the camera.

In such a state, the support 33 is moved by a driving means (not shown). Then this support 3
The lifting cylinders 35 and 36 supported by 3 are moved together. When the support base 33 moves to the left, the squeegee 38 of the right lifting cylinder 36 is lowered, and the cream solder 17 on the mask plate 30 is implanted in the mask plate 30 by the squeegee 38. Push into 31. Accordingly, a predetermined amount of the cream solder 17 is extruded from the lower end of the hollow nozzle 31, and the cream solder 17 is placed at a predetermined position on the circuit board 10.
Is applied.

When the application of the cream solder 17 is completed, the board backup plate 27 descends again, and the circuit board 10
Is placed on the conveyor belt 26. In addition, since the board stopper 28 is lowered, the circuit board 10
Is discharged to the left.

Next, a description will be given of a reflow furnace for soldering the circuit board 10 on which the components 18 with leads and the shield case 20 are mounted as necessary after the application of the cream solder 17 as described above.
As shown in FIG. 1 and FIG. 12, the reflow furnace includes preheat zones 43 and 44, a reflow zone 45, and a cooling zone 46. A single or a plurality of exhaust pipes 47 are provided on the upper part of such a reflow furnace as needed.

Further, a conveyor 50 and a heater 51 are arranged in such a reflow furnace. The circuit board 10 introduced into the reflow is gently conveyed by the conveyor 50 from the preheating zone 43 side to the cooling zone 46 side. At this time, the preheating is performed by the heater 51 disposed therebelow. Alternatively, heating for reflow is performed, whereby the solder powder in the cream solder 17 is melted and soldering is performed.

Particularly, in this reflow furnace, the conveyor 50 and the heater 51 are inclined in the width direction of the conveyor 50 as shown in FIG. The heater 51 is arranged below the conveyor 50 in a state where the heater 51 is inclined so as to be parallel to the circuit board 10 on the conveyor 50 in accordance with the inclination of the conveyor 50.

As described above, since the conveyor 50 constituting the means for transporting the circuit board 10 is inclined, the circuit board 10
Will pass above the heater 51 in an obliquely inclined state. In particular, the circuit board 10 on which the cream solder 17 is applied is conveyed in a state in which the surface on which the cream solder 17 is applied is on the lower side and in an oblique state. In this case, it is possible to reduce the amount of solder falling as compared with the case where the soldering is performed.

The direction of inclination of the circuit board 10 conveyed by the conveyor 50 is not necessarily limited to the direction shown in FIG. 12, and the circuit board 10 may be inclined so that the left portion becomes lower. Alternatively, the sheet may be transported obliquely along the transport direction. Further, the angle of inclination of the circuit board 10 on the conveyor 50 is not necessarily limited to the illustrated angle, but is preferably inclined at an angle of 95 ° or less.

The reflow furnace is applicable to both tunnel type and spot reflow type reflow furnaces. Further, as a transport method, a net type using a transport net can be applied in addition to a chain type. Further, the inclination angle of the conveyor 50 may be variably adjusted. That is, the inclination angle may be adjusted by the angle adjustment mechanism according to the type of the circuit board 10 and the amount of the cream solder 17 applied. At this time, the inclination angle of the heater 51 may be adjusted together.

FIG. 12 shows a reflow furnace according to this embodiment.
As shown in FIG.
In this case, the sheet is heated and reflowed while being transported. As described above, since the posture of the circuit board 10 becomes oblique at the time of reflow, the amount of solder falling in the reflow process is reduced.

Therefore, it is possible to reduce the number of times of cleaning the inside of the reflow furnace due to the falling of the solder, thereby reducing the number of cleaning steps. In addition, since the fall of the cream solder 17 is reduced, the unsoldered portion is reduced, the reliability of the electronic circuit is improved, and the man-hour for repairing the solder can be reduced. Become like In addition, the amount of solder that falls is reduced, so that the amount of solder used is reduced and the cost of solder can be reduced. Further, since the fall of the solder is reduced, it is possible to reduce the amount of defective solder generated by the fall.

[0033]

According to the present invention, a substrate is transported in an oblique posture in a reflow apparatus in which the surface to which the cream solder is applied is heated downward and transported while soldering is performed. Things.

Therefore, according to the present invention, it is possible to reduce the fall of the solder in the reflow step, reduce the number of cleaning steps in the reflow furnace, suppress the occurrence of unsoldered, and reduce the amount of solder used. It becomes possible.

According to the configuration in which the substrate is inclined at right angles to the direction of conveyance by the conveying means and in the width direction of the conveying means, soldering is performed in a state where the circuit board is inclined in the width direction of the conveying means. In other words, it is not necessary to incline the conveying means along the conveying direction.

According to the configuration in which the substrate is inclined at an angle of 90 ° or less with respect to the horizontal direction, it is possible to perform soldering while transporting the substrate at an appropriate inclination angle.

According to the configuration in which the heater for heating the substrate is arranged below the transfer means, and the heater is arranged in an oblique posture so as to be substantially parallel to the substrate to be transferred obliquely, The distance between the substrate and the heater is substantially constant at all positions on the circuit board, and uniform soldering can be performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a circuit board for describing a manufacturing process of a high-frequency circuit in order.

FIG. 2 is a cross-sectional view of a circuit board for explaining a manufacturing process of the high-frequency circuit in order.

FIG. 3 is a cross-sectional view of a circuit board for explaining a manufacturing process of the high-frequency circuit in order.

FIG. 4 is a cross-sectional view of a circuit board for explaining a manufacturing process of the high-frequency circuit in order.

FIG. 5 is a cross-sectional view of a circuit board for explaining a manufacturing process of the high-frequency circuit in order.

FIG. 6 is a cross-sectional view of a circuit board for explaining a manufacturing process of the high-frequency circuit in order.

FIG. 7 is a cross-sectional view of a circuit board for sequentially explaining a manufacturing process of the high-frequency circuit.

FIG. 8 is a cross-sectional view of a circuit board for explaining a manufacturing process of the high-frequency circuit in order.

FIG. 9 is a cross-sectional view of a circuit board for explaining a manufacturing process of the high-frequency circuit in order.

FIG. 10 is a longitudinal sectional view of a main part showing an apparatus for applying a cream solder for soldering a component with a lead.

FIG. 11 is a side view of a reflow furnace.

FIG. 12 is a longitudinal sectional view of a reflow furnace.

FIG. 13 is a side view of a conventional reflow furnace.

FIG. 14 is a longitudinal sectional view of a conventional reflow furnace.

[Explanation of symbols]

1, 2 ‥‥ preheat zone, 3 ‥‥ reflow zone,
4 ‥‥ cooling zone, 5 ‥‥ conveyor, 6 ‥‥ heater, 1
0 ‥‥ circuit board, 11 ‥‥ cream solder, 12 ‥‥ chip component, 13 ‥‥ solder, 17 ‥‥ cream solder,
18 ‥‥ leaded parts (air core coil), 19 ‥‥ lead, 20 ‥‥ shield case, 21 ‥‥ claw, 22 ‥‥
Solder, 25mm frame, 26mm conveyor belt, 27
{Substrate backup plate, 28} Substrate stopper, 30} Mask plate, 31} Hollow nozzle, 3
2 ‥‥ squeegee guide, 33 ‥‥ support base, 35, 36 ‥
{Elevating cylinder, 37, 38} Squeegee, 43, 44
‥‥ Preheat zone, 45 ‥‥ Reflow zone, 46
{Cooling zone, 47} exhaust stack, 50} conveyor,
51 ‥‥ heater

Claims (4)

[Claims] 1. A method of applying cream solder on a substrate, mounting a component on the opposite surface of the substrate, and transporting the surface of the substrate with the cream solder applied downward while heating the component. A reflow soldering apparatus configured to melt the cream solder to perform soldering, wherein the substrate is transported in an oblique posture. 2. The reflow soldering apparatus according to claim 1, wherein the substrate is inclined in a direction perpendicular to a direction of conveyance by the conveying means and in a width direction of the conveying means. 3. The reflow soldering apparatus according to claim 1, wherein said substrate is inclined at an angle of 90 ° or less with respect to a horizontal direction. 4. A method according to claim 1, wherein a heater for heating the substrate is provided below the transfer means, and the heater is arranged in an oblique posture so as to be substantially parallel to the substrate to be transferred obliquely. The reflow soldering apparatus according to claim 1, wherein: