JPH02202094A - Board warpage preventing method and device therefor - Google Patents

Abstract

PURPOSE:To realize a board of excellent soldability by a method wherein the upside of a warpage preventive plate in a solder tank is made to abut firmly against the underside of the board to prevent it from warping downward to become convex state as both of the sides of the board are held by two or more feed pawls. CONSTITUTION:The upside 38a of a warpage preventive plate 38 provided in a soldering tank is made to butt against the underside 2a of the board 2 as both the sides 2a and 2b of a board 2, on which an electronic component 1 is mounted, transferred on a conveyor are held by two or more feed pawls 5 when the board is soldered. The force which makes the board 2 warp downward to become convex state is supported by the warpage preventive plate 38 to prevent the board 2 from warping, and the upside 38a of the warpage preventive plate 38 is made to sink into a molten solder 4 while an oxide removing device is in operation. By this setup, an excellent soldability can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method and device for preventing warpage of a board in an automatic soldering device, and more particularly, the present invention relates to a method and device for preventing warping of a board in an automatic soldering device, and in particular, a method and device for preventing warpage of a board in an automatic soldering device. An anti-warp plate that supports the force that causes the board to warp downward when it is separated from the solder is placed in the solder tank so that it can move in and out from the surface of the molten solder, preventing the board from warping and preventing oxides from being removed. The present invention relates to a method and apparatus for preventing warpage of a board, which allows extremely good soldering performance to be obtained.

Conventional technology A conventional example will be explained with reference to FIG. 6. In the conventional automatic soldering device 7, a board 2 on which an electronic component 1 is mounted is conveyed, and the board 2 is applied to molten solder 4 in a solder bath 3. The lower surface 2a of the starts contact, is heated and its temperature increases,
When the substrate 2 is separated from the molten solder 4, as shown in FIG.
Since the board 2 is held by the groove 5a at its tip and cannot move in its width direction, the board 2 warps downward in a convex manner, which has various negative effects on soldering performance. The following may be the reason why the substrate 2 curves downward in a convex manner during contact with the molten solder 4.

(11 The weight of the board 2 itself and the weight of the electronic component 1 are
acts downward so as to maximize the downward deflection of the center portion 2c in the width direction.

(2) When the board 2 tries to move away from the molten solder 4, the surface tension of the molten solder 4 acts downward on the bottom surface 2''a of the board 2, but the center part 2c in the width direction of the board 2 is at the lowest point. It is easy to bend.

(3) Since the lower surface 2a of the substrate 2 comes into contact with the molten solder 4, the temperature of the lower surface is higher than that of the upper surface 2d, so the thermal expansion of the lower surface 2a is greater than that of the upper surface 2d, so the substrate 2 is inevitably lowered. It curves convexly.

The above-mentioned factors cause the substrate 2 to warp downward in a convex manner.
The timing of separation from the molten solder 4 is quite different between the vicinity of both side surfaces 2b and the center part 2c in the width direction, resulting in different soldering conditions at each position in the width direction, and good soldering performance cannot be obtained. . That is, for example, since the central portion 2C is the last to leave the molten solder 4, soldering is always completed in the central portion, and soldering defects such as bridges occur intensively in this portion.

Further, as a result of the substrate 2 convexly warping downward, the central portion 2c sinks into the molten solder 4, and the molten solder 4 flows onto the upper surface 2d of the substrate 2, causing fogging, resulting in defective soldering. Moreover, in order to prevent this, if the height of the surface 4a of the molten solder 4 is lowered,
It is expected that the lower surface 2a near both side surfaces 2b of the substrate 2 will not come into contact with the molten solder 4, making soldering impossible.

In order to prevent such warping of the board 2, conventionally, a fixed support member that supports the center part 2c of the board 2 from below is disposed inside the solder bath 3, or a plurality of protrusions are formed on the circumference. A system in which a rotating body is arranged and the central part 2C of the substrate 2 is intermittently supported by the protrusion has been put into practical use.
It is technically difficult to prevent the oxide covering the surface 4a of the substrate 2 from interfering with the work of skimming the surface 4a with the oxide removal device, and the height is sufficiently high to prevent warping of the substrate 2. It was difficult to set up.

As a result, when the substrate 2 tries to separate from the molten solder 4, the surface tension of the molten solder 4 acting downwardly against the lower surface 2a of the substrate 2 causes the central portion 2C of the substrate 2 to warp downward in a convex manner, and this portion However, soldering bridges and the like had the disadvantage that defects still occurred.

Still another method is to provide a board hanging member that moves at the same speed as the conveyor from above the conveyor, and the hanging member supports the central part 2c of the board 2 to prevent it from warping. has also been put into practical use, but the equipment needed to prevent warping has become extremely large-scale, and automatic soldering costs about half the cost of the entire device, making it extremely uneconomical. Ta.

Purpose The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art.The purpose of the present invention is to use an automatic soldering device to solder multiple parts on both sides of a board on which electronic components are mounted. a solder bath device supported in a vertically movable manner so that a first fluid pressure cylinder approaches and returns to a substrate gripped by a feed claw and conveyed by a conveyor; and a solder bath device mounted on the solder bath device. One end is supported by a second fluid pressure cylinder so as to be movable up and down relative to the solder tank device, and the other end is disposed within the solder tank constituting the solder tank device. and a warpage prevention member that operates a second fluid pressure cylinder to bring the warpage prevention plate into contact with the bottom surface of the board when the board is separated from the molten solder in the solder tank, thereby preventing the board from separating from the molten solder. By preventing the board from warping by supporting the board's own weight and the surface tension of the molten solder, which act downwardly against the bottom surface of the board, with the warp prevention member, it is possible to prevent the board from warping with an extremely simple configuration. To prevent the board from warping, to ensure that the timing of separation from the molten solder is the same for all positions in the width direction of the board, to prevent defects in bridges and other soldering, and to prevent molten solder from covering the top surface of the board. Good soldering is about performance.

Another purpose is to ensure that when the device for removing oxides on the surface of molten solder is activated, the anti-warp plate is submerged in the molten solder, so that oxides can be removed sufficiently. be.

Configuration In short, the method of the present invention (claim 1) is such that a board on which electronic components are mounted and being conveyed by a conveyor is placed in a solder tank during soldering, with both sides of the board being gripped by a plurality of feed claws. The upper surface of the warpage prevention plate is brought into contact with the lower surface of the substrate to prevent a force that causes the board to warp downwardly, and
During operation of the oxide removal device, the upper surface of the warpage prevention plate is submerged in molten solder.

Further, in the device of the present invention (claim 2), both sides of the board on which electronic components are mounted are gripped by a plurality of feed claws, and the first a solder tank device supported so as to be movable up and down by a fluid pressure cylinder; and one end supported so as to be movable up and down relative to the solder tank device by a second fluid pressure cylinder mounted on the solder tank device. The other end is disposed in a solder tank constituting the solder tank device, and when the board immersed in the molten solder of the solder tank is pulled away from the molten solder, the top surface of the warpage prevention plate is brought into contact with the bottom surface of the board. and a warpage prevention member that supports a force that causes the substrate to warp downward in a convex manner when the board is brought into contact with the board, and the upper surface of the warpage prevention plate is submerged in the molten solder while the oxide removal device is in operation. It is something to do.

The present invention will be explained below based on embodiments shown in the drawings. 1st
In the figures and FIG. 2, a board warpage prevention device 8 according to the present invention includes a solder bath device 9 and a warpage prevention member 10.

The solder tank device 9 is composed of a solder tank 3, a heating device 6, and a first fluid pressure cylinder 11, and is configured to apply pressure to the bottom surface 2a of a board 2 on which an electronic component 1 is mounted and transported by a conveyor (not shown). On the other hand, the molten solder 4 in the solder bath 3 is brought into contact with the first fluid pressure cylinder 11 by operating the first fluid pressure cylinder 11.

The solder tank 3 is formed in the shape of a square having a surface area capable of accommodating the substrate 2 and a predetermined depth, and the lower surface 3 a of the solder tank is fixed to the upper surface 6 a of the heating device 6 .

The heating device 6 includes a heater section 13 made of an aluminum alloy with good thermal conductivity and an outer frame member 14, and the temperature of the heater section 13 is automatically controlled by a temperature control device (not shown). It has become. Further, the heating device 6 is fixed to the support base 15 on the lower surface 14a of the outer frame member 14.

As the first fluid pressure cylinder 11, devices such as an air cylinder and a hydraulic cylinder can be mounted, and in this embodiment, an air cylinder that is easy to handle is used. The first fluid pressure cylinder is fixed to the base 16, and the piston rod 18 is connected to the nut 1 at the tip 18a.
It is connected to the support stand 15 by 9. The operation of the piston rod 18 is controlled by the electronic control device (
(not shown), and the piston rod 1
8 causes the solder bath 3 to reciprocate in the vertical direction. Further, the operating stroke of the piston rod can be adjusted to a predetermined size by a limiting device (not shown).

One end 10a of the warpage prevention member 10 is fixed by a screw 22 to an upper surface 21a of an angle member 21 that is supported so as to be slidable in the vertical direction by a plurality of guide shafts 20 fixed to a base 16.

The angle member 21 is attached to a mounting plate 40 fixed to the solder tank 3.
The piston rod 23 of the second fluid pressure cylinder 12 (for example, an air cylinder) is fixed by a nut 24 to the tip 23a of the piston rod 23 attached to the piston rod 23 via brackets 41, 42. The upper limit of the operation of the piston port/socket 23 is the base 1.
The upper surface 21a of the angle member 21 is in contact with the cushion 26 fixed to one end 25a of the stopper screw 25 screwed to the base 16, and the lower limit of the operation of the piston rod 23 is reached by the stopper screwed to the base 16. One end 28 of the screw 28
This is the position where the lower surface 21b of the angle member 21 is in contact with the cushion 29 fixed to the point a.

The stopper screws 25, 28, each having a set position, are fixed to the base 16 by means of a lock nut 30.

The other end 10b of the warpage prevention member 10 is formed into a rectangular shape that can be accommodated in the solder bath 3, and has plate members 31 and 32.
It has a framework structure in which the parts are combined at right angles, corner members 33 are placed on the corners, and they are fixed to each other with screws 34.

In addition to the illustrated embodiment, it is of course possible to form the one end 10b integrally by a method such as pressing or welding.

A plurality of long holes 31a are formed in the plate member 31,
Mounting bracket 3 whose mounting position can be freely adjusted along the length
5 is fixed with a screw 36. A warpage prevention plate 38 is attached to the mounting bracket with screws 39.

In the illustrated embodiment, the upper surface 38a of the warpage prevention plate 38 has a smooth surface, but even if the upper surface 38a is provided with comb-shaped protrusions intermittently, the same purpose can be achieved. can be achieved. Further, the warpage prevention plate 38 has a plurality of elongated holes 31a formed in the plate member 31 so that a plurality of plates can be used depending on the size of the substrate 2.

In the method of the present invention, a plurality of feed claws 5 grip both sides 2b of the board 2 on which the electronic component 1 is mounted and the board 2 is transported by a conveyor (not shown). The upper surface 38 of the warpage prevention plate 38 disposed within 3
a is brought into contact with the lower surface 2a of the substrate 2 to support the force that causes the substrate 2 to curve downward in a convex manner, thereby preventing the substrate 2 from warping, and during the operation of the oxide removal device, the warping prevention plate 3
8 is submerged in the molten solder 4.

Function The present invention is constructed as described above, and its function will be explained below. As shown in FIG. 3, the board 2 with the electronic components l mounted on both sides 2b of the board 2 gripped by a plurality of feed claws 5 is conveyed directly above the solder bath 3 and is temporarily stopped at that position. .

As shown in FIG. 4, the piston rod 18 of the first fluid pressure cylinder 11 operates in the direction of arrow A to lift the solder bath 3 upward, so that the surface 4a of the molten solder 4 is exposed to the bottom surface of the substrate 2.
a, and the substrate is immersed in the molten solder 4 for a predetermined time.

Almost simultaneously with the operation of the first fluid pressure cylinder 11, the piston rod 23 of the second fluid pressure cylinder 12 is operated in the direction of arrow B, and the warpage prevention member 10 is also lifted in the direction of arrow B, so that the upper surface 38a of the warpage prevention plate 38 is uniformly abuts against the lower surface 2a of 2. In this case, the lower surface 2a of the substrate 2 comes into contact with the molten solder 4, and the thermal expansion of the lower surface 2a becomes larger than that of the upper surface 2d, which causes a force to bend the substrate 2 downward. , this force is supported by the warp prevention plate 38, so
The substrate 2 does not curve downward in a convex manner, as shown in FIG.
It will remain horizontal.

Next, after immersing the substrate 2 in the molten solder 4 for a predetermined time, the first fluid pressure cylinder 11 is opened as shown in FIG.
The piston rod 18 operates in the direction of arrow C to open the solder bath 3.
is pulled down, and when the substrate 2 tries to separate from the molten solder 4, the surface tension of the molten solder acts downward on the lower surface 2a of the substrate 2, causing the substrate to curve downward in a convex manner. This force acts on the warpage prevention plate 38.
Since the board 2 is supported by the support and does not warp downward convexly, the center part 2C and the vicinity of both sides 2b of the board 2 are separated from the molten solder 4 at the same time. The defects in soldering such as the above are eliminated, and the lead wires 1a of the electronic component 1 mounted on the board 2 are soldered very well at the locations where soldering is required.

After that, the piston rod 23 of the second fluid pressure cylinder 12
operates in the direction of the arrow to return the warpage prevention member 10 to its original position, and when the top surface 38a of the warpage prevention plate 38 has sunk into the molten solder 4, the oxide covering the surface 4a of the molten solder 4 is removed. It is removed by an oxide remover (not shown). In this case, since the warpage prevention plate 38 is submerged in the molten solder, there is no problem with the operation of the oxide removal device, and oxides can be completely removed.

When the soldering of the board 2 is completed, the board is transferred to the next process, and the next unsoldered board 2 is transferred to the feed claw 5 instead.
It is held and transported by As shown in FIG. 3, the board 2 temporarily stops when it reaches directly above the solder bath 3, and
Thereafter, the above steps are repeated to automatically continue soldering.

Effects The present invention provides an automatic soldering device as described above, in which both sides of a board on which electronic components are mounted are gripped by a plurality of feed claws, and a first soldering process is performed on the board being conveyed by a conveyor.
A solder bath device is supported so as to be movable up and down so as to perform approach and return operations by a fluid pressure cylinder, and a second fluid pressure cylinder mounted on the solder bath device allows one end to be moved relative to the solder bath device. A warpage prevention plate supported so as to be vertically movable is disposed in the solder tank that constitutes the solder tank device, and operates a second fluid pressure cylinder when the board is separated from the molten solder in the solder tank upon completion of soldering. and a warpage prevention member configured to bring the warpage prevention plate into contact with the bottom surface of the board, and prevent the board's own weight and molten solder from acting downwardly against the bottom surface of the board when the board tries to separate from the molten solder. Since the surface tension etc. of
The extremely simple configuration has the effect of preventing the board from warping during soldering, and the timing of separation from the molten solder is the same for all positions in the width direction of the board, preventing bridges and other solder connections from being defective or molten solder on the board. It is possible to prevent fogging on the upper surface, and good soldering has the effect of improving performance.

Also, when the oxide removal device on the surface of the molten solder operates,
Since the warpage prevention plate is made to be submerged in the molten solder, there is an effect that oxides can be sufficiently removed.

[Brief explanation of the drawing]

1 to 5 relate to embodiments of the present invention, in which FIG. 1 is a perspective view of a device for preventing warpage of a substrate, FIG. 2 is a vertical sectional view of main parts of the device for preventing warpage of a substrate, and FIG. FIG. 4 is a vertical cross-sectional view of the main part showing a state in which the board gripped by the claws is supported by the board warpage prevention device, and FIG. Figure, 5th
The figure is a vertical sectional view of the main part showing the state in which the board warpage prevention device is activated when pulling the board away from the solder tank, and Figure 6 shows the state of board warp that occurs when pulling the board out of the solder tank in a conventional example. FIG. ■ is an electronic component, 2 is a board, 2a is a bottom surface, 2b is a side surface, 3
1 is a solder tank, 4 is a molten solder, 5 is a feeding claw, 8 is a board warpage prevention device, 9 is a solder tank device, 10 is a warpage prevention member, 10
a is one end, 10b is the other end, 11 is a first fluid pressure cylinder, 12 is a second fluid pressure cylinder, 38 is a warpage prevention plate, 3
8a is the top surface. Patent applicant Yokota Machinery Co., Ltd.

Claims (1)

[Scope of Claims] 1. When a plurality of feed claws grip both sides of a board on which electronic components are mounted and are being conveyed by a conveyor, a warpage prevention plate disposed in a solder tank is used during soldering. The upper surface is brought into contact with the lower surface of the substrate to prevent a force that would cause the substrate to warp downward, and the upper surface of the warp prevention plate is submerged in molten solder while the oxide removal device is in operation. A method for preventing board warping in automatic soldering equipment. 2. Both sides of a board on which electronic components are mounted are gripped by a plurality of feed claws, and supported so as to be movable up and down by a first fluid pressure cylinder so as to approach and return to the board being conveyed by a conveyor. a solder tank device, one end of which is supported so as to be movable up and down relative to the solder tank device by a second fluid pressure cylinder mounted on the solder tank device, and the other end forming the solder tank device. When the board disposed in a solder tank and immersed in the molten solder of the solder tank is pulled away from the molten solder, the top surface of the warpage prevention plate is brought into contact with the bottom surface of the board to make the board convex downward. An apparatus for preventing warpage of a substrate, comprising a warpage prevention member that supports a warping force and that allows the upper surface of the warpage prevention plate to be submerged in molten solder during operation of the oxide removal apparatus.