JPS63289992A - Method and apparatus for preventing substrate from warping - Google Patents

Abstract

PURPOSE:To prevent a substrate from warping in case of soldering it with a simple structure and to obtain preferable soldering performance by rotating the end grooves of a plurality of feeding claws upward to generate a force for warping the substrate toward and upward and outward directions in a state that both sides of the substrate are held by the claws. CONSTITUTION:The end grooves 11 of a plurality of feeding claws 9 are rotated upward in response to a force for warping a substrate 2 to be conveyed by a conveyor by placing electronic components thereon toward a downward and outward directions in case of soldering the substrate 2 to generate a force for warping the substrate 2 toward an upward and outward directions in a state that both the sides of the substrate 2 are held by the claws 9 to prevent the substrate 2 from warping. Further, a feeding claw 9 composed at the end grooves 11 rotatably by holding both the side faces of the substrate 2 conveyed by a conveyor by placing electronic components thereon by the end groove 11, and a feeding claw rotatably driving mechanism 10 for generating a force for warping the substrate 2 toward an upward and outward directions by rotating the end grooves 11 of the claws 9 upon advancing of soldering to generate a force for warping the substrate toward the upward and outward directions are provided to construct a substrate warpage preventing apparatus 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method and device for preventing warping of a board in an automatic soldering device, and particularly to a method for soldering a groove at the tip of a feed claw that grips both sides of a board on which components are mounted. A method for preventing warpage of a board by rotating the board upward as the soldering progresses to generate a force that causes the board to warp upward in a convex manner, thereby achieving extremely good soldering performance. and devices.

Prior art A conventional example will be explained with reference to FIGS. 18 and 19. In the conventional automatic soldering device, electronic components 1
The board 2 on which is mounted is transported in the direction of arrow F, and the lower surface 2a of the board 2 starts to come into contact with the molten solder 4 in the solder tank 3 (in the illustrated example, a jet solder tank), and is heated and its temperature increases. When the board 2 rises and leaves the molten solder 4, the first
As shown in Fig. 8, both sides 2b are gripped by the tip groove 5a of the feeding claw 5 connected to the conveyor and cannot move in the width direction, so the substrate 2 may warp downward. However, soldering had various negative effects on 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 separate from the molten solder 4, the surface tension of the molten solder 4 acts downwardly on the bottom surface 2a of the board 2, but the center part 2C in the width direction of the board 2 is bent most downwardly. easy.

(3) When the substrate 2 is heated by the molten solder 4, it thermally expands and tries to extend in its width direction, but both side surfaces 2b are fixed by the feed claws 5 and cannot move.

Furthermore, since the temperature of the lower surface 2a of the substrate 2 is higher than that of the upper surface 2d, the thermal expansion of the lower surface 2a is greater than that of the upper surface 2d, so that the substrate 2 inevitably warps downward.

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 2d and the central 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 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 poor soldering. In addition, in order to prevent this, if the height of the wave crest 4a of the molten solder 40 is lowered,
It is expected that the lower surface 2a near both side surfaces 2b of the board 2 will not come into contact with the melted solder 4, making soldering impossible.

In order to prevent such warpage of the board 2, conventionally, a fixed support member that supports the center portion 2C of the board 2 from below is placed inside the solder bath 3, or a plurality of protrusions are formed on the circumference. Practical systems have been put into practice in which a rotating body is arranged to intermittently support the central part 2C of the board 2 with the protrusion. If 1a exists, it must be arranged to avoid it, which poses major operational constraints, and it may not be usable depending on the arrangement of electronic components 1.

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 drawbacks of the prior art described above, and its purpose is to perform automatic soldering in an apparatus where a board on which electronic components are mounted and is transported by a conhair. A feed claw whose both sides are gripped by tip grooves and which is rotatable, and a force that rotates the tip groove of the feed claw upward as soldering progresses, causing the board to curve upward in a convex manner. and a feed pawl rotation drive mechanism that rotates the tip groove of the feed pawl upward in response to the force that causes the board to warp convexly downward during soldering, thereby causing the board to warp convexly upward. By causing this to occur and preventing the board from warping, it is possible to prevent the board from warping during soldering with an extremely simple configuration, and it is possible to prevent the board from warping at any position in the width direction of the board. The timing of separation from the molten solder should be the same, bridges and other soldering should be prevented from being defective, and the molten solder should not cover the top surface of the board, and good soldering should ensure good performance. In addition, other purposes are
To improve workability by eliminating the need for arranging a support member for a board in a solder bath so that a board with any arrangement of electronic components can be used without any problem.

Configuration: In short, the method of the present invention involves gripping both sides of a board on which electronic components are mounted and being transported by a conveyor by a plurality of feed claws, and applying a force that causes the board to curve downward in a convex manner during soldering. The present invention is characterized in that warpage of the substrate is prevented by rotating the tip groove portion of the feed claw upward to generate a force that causes the substrate to curve upward in a convex manner.

Furthermore, the device of the present invention includes a feed pawl configured to grip both sides of a board on which electronic components are mounted and conveyed by a conveyor with a tip groove portion, and the tip groove portion is configured to be rotatable; The present invention is characterized by comprising a feed pawl rotation drive mechanism that rotates upward as the soldering progresses to generate a force that causes the board to curve upward in a convex manner.

The present invention will be explained below based on embodiments shown in the drawings. 1st
In the figures and FIG. 2, a substrate warpage prevention device 8 according to the present invention includes a feed claw 9 and a feed claw rotation drive mechanism 10. As shown in FIG.

The feeding claw 9 is configured to grip both side surfaces 2b of the substrate 2 on which the electronic component 1 is mounted and transported by the conveyor 17 with a tip groove 11, and the tip groove is rotatable.

The tip groove portion 11 is rotatably attached to the feed claw main body 13 by a pin 12, and the pin 12 passes through a bent portion 13a formed at the lower end of the feed claw zero body 13 and extends from the bent portion. A U-shaped bent portion 1 of the tip groove portion 11 protrudes from both sides thereof.
It is press-fitted into 1a.

The bent portion 11a of the tip groove portion 11 has vertical portions 11b formed on both sides of the narrow tip groove mounting portion 13b rising from the bent portion 13a of the feed claw body 13, and the vertical portions are attached to the upper end. They are connected to each other by a formed upper bent portion 11c. A gap C is formed between the inner surface lid of the bent portion 11C and the feeding claw main body 13, so that the bent portion can approach the feeding claw main body 13. The tip groove 11 is configured so that the entire tip groove 11 can be rotated about the pin 12 by pressing against the feed pawl zero body 13.

This rotation causes the tip groove portion 11 to rotate upward, gripping both side surfaces 2b of the substrate 2, and causing them to curve upward in a convex manner. The same is true for the tip groove portion 11 of.

The feeding claw main body 13 has an L-shaped bent portion 13c formed at its upper end, and the bent portion is fixed to a chain 16 constituting the conveyor 17 with two setscrews 15 via a mounting plate 18. . The parts connected to the tip grooves 11 are attached continuously along the chain 16 as shown in FIG.
It is configured to be conveyed by gripping both side surfaces 2b of.

The groove lie of the tip groove 11 can be formed in various shapes, but for example, the one shown in FIG. It is formed as a groove. Furthermore, the structure shown in FIG. 7 is configured such that the groove lie widens stepwise as it approaches the opening 11f, so that it can accommodate three types of substrates having different thicknesses. Also, is what shown in Figure 8 a modification of the one shown in Figure 7? The stepped portion of a11e is formed not vertically but obliquely so as to be able to accommodate substrates 2 of three different thicknesses. Note that the depth G of the groove lie is deep, and its width B
It is clear that the closer t is to the thickness t of the substrate 2, the stronger the gripping force on the substrate becomes. Also, as shown in Figure 2,
The lower part 11g of the groove lie of the tip groove 11 is formed into a forked shape, and is configured so that the molten solder 4 can flow downward. It is manufactured by precision casting using the cost wax casting method.

The feed pawl rotation drive mechanism 10 rotates the tip groove portion 11 of the feed pawl 9 upward as soldering progresses, and generates a force that causes the board 2 to curve upward in a convex manner. The claw pressing cam 20 is attached to the boss portion 2 by the set screw 21.
2, and the boss portion is fixed to the feed pawl pressing cam adjustment rod 2.
It is fixed at 3. The feed pawl pressing cam adjustment rod is
Bracket 2 fixed to base 24 with bolts 25
6 via a bushing 28, and a threaded portion 23a is formed at one end of the feed press cam adjustment rod 23, and the threaded portion 23a is attached to the pair of bearing portions 29, 30 of the bracket 2G. The threaded part is slidably passed through the threaded part, and an adjusting nut 31 is screwed onto the threaded part 23a between the pair of bearing parts 29 and 300, and by rotating the adjusting nut, the feeding press cam adjusting rod 23 is adjusted. The feed press cam 2 moves in a direction perpendicular to the direction of movement of the substrate 2.
0 in the same direction can be adjusted. This bracket 26 is attached to the base 24 on one side.
A total of four sets are provided on both sides of the conveyor 17.

A feed claw rotation drive mechanism 10 having the same configuration is provided above the conveyor 17 on both sides of the substrate 2. With this configuration, the feeding die pressing cam adjustment rod 23 located in front of the forward direction of the board 2 is brought closer to the feeding pawl 9, and by increasing the degree of approach, the feeding die pressing cam is adjusted as the soldering progresses. 20 can increase the amount by which the bent portion 11c of the tip groove 11 of the feed pawl 9 is displaced, and is therefore set so as to gradually increase the force that causes the substrate 2 to curve upwardly by the tip groove 11.

Then, in the method of the present invention, the board 2, on which the electronic component 1 is mounted and transported by the conveyor 17, is gripped by a plurality of feed claws 9 on both sides 2b, and the board 2 is convex downward during soldering. This is a method of preventing the substrate 2 from warping by rotating the tip groove 11 of the feed claw 9 upward in accordance with the warping force to generate a force that causes the substrate 2 to warp in an upwardly convex manner.

Function The present invention is constructed as described above, and its function will be explained below. The feed pawl rotation drive mechanism 10 is provided on each side of the conveyor 17, and the inclination angle of the feed die pressing cam 20 with respect to the advancing direction of the substrate 2 is set by appropriately adjusting two adjusting nuts 31. ,
Due to its inclination angle, even if the feeding claw 90 is moved parallel to the substrate 2 by the conveyor 17, the tip groove 1
The degree to which the bending portion 11c of the board 1 is pressed by the feed pressing cam 20 is set to gradually increase as the soldering progresses, and the force that causes the board 2 to curve upwardly is increased. .

That is, if the amount of rotation of the adjustment nut 31 on the rear side in the direction of movement indicated by the arrow F on the board 2 is reduced, and the amount of rotation of the adjustment nut 31 on the front side in the direction of movement is increased, the feed die pressing cam 20 can be moved forward by the feed pawl 9. As the tip groove 11 advances, the degree of pressure gradually increases as shown by arrow A, and the angle at which the groove lie is inclined upward as shown by the arrow A is increased. becomes larger.

This is because as the soldering progresses, the temperature of the board 2 increases, and the force that causes the board 2 to curve downward in a convex manner increases. The force that tends to increase the downward convex curve and the upward convex curve cancel each other out, and as a result, the substrate 2 is adjusted so that it is maintained in a horizontal state while it is being advanced.

In this way, the inclination angle of the feeding die pressing cam 20 is adjusted using the adjusting nut 31, and the feeding die pressing cam 20 is adjusted by taking into account the width and thickness of the board 2 that actually flows, the weight of the electronic component 1 mounted on it, etc. The inclination angle is determined by appropriate manual operation.

By setting the inclination angle of the feed die pressing cam 20 in this way, the shape of the soldering inside of the board 2 is determined as shown in FIGS. 9 to 16. That is, FIG. 9, FIG. 11, FIG. 13, and FIG. 15 illustrate the influence of upward rotation of the tip groove portion 11 when it is assumed that there is no force that causes the substrate 2 to warp downward. 10, 12, 14, and 16 show the actual state of the substrate 2 corresponding to each of FIGS. 9 to 15, respectively.

In FIG. 9, the tip groove portion 11 is kept substantially horizontal, and as a result, the actual substrate 2 is also kept horizontal as shown in FIG.

In addition, in FIG. 12, the board 2 is in the initial stage of soldering, and if there is no force to warp the board 2 downward,
Since the tip groove 11 has begun to rotate upward to some extent, the substrate 2 will curve upward in a convex manner as shown in FIG. 11, but in reality, as shown in FIG. It is kept horizontal by the weight of part 1.

Moreover, in FIG. 13, the upward rotation angle of the tip groove 11 becomes even larger, and in this case, since the board 2 is near the end of soldering, there is a force that tends to warp the board 2 in a downward convex manner. becomes thicker (becomes thicker), which balances the force that tends to warp the substrate 2 upward in a convex manner as shown in FIG. 13, and as a result, the substrate 2 is still kept horizontal as shown in FIG.

In addition, in FIG. 15, the upward rotation angle of the tip groove 11 at the time when the board 2 separates from the molten solder 4 and soldering is completed is the maximum, and as a result, if the board 2
If there were no force to warp the board convexly downward, the board 2 would warp greatly convexly upward as shown in FIG. 15, but in reality, surface tension from the molten solder 4 also acts, Since the thermal expansion of the substrate 2 also reaches its maximum, the substrate 2 will still remain horizontal as shown in FIG.

As a result, even if the molten solder 4 exerts surface tension on the substrate 2, the substrate 2 will not curve downward in a convex manner, so that the central portion 2c and the vicinity of both side surfaces 2b of the substrate 2 will be separated from the molten solder 4 at the same time. As a result, defects in soldering such as bridges, which were mainly occurring in the central portion 2C, are eliminated, and very good soldering results can be obtained.

Further, the upward rotation angle of the tip groove 11 as shown in FIGS. 9 to 16 is adjusted by manual operation of the adjustment nut 31 of the feed pawl rotation drive mechanism 10 according to the characteristics of each substrate 2, as described above. Therefore, the tip groove 11 can be rotated in the best condition for any type of substrate 2 to generate a force that causes the substrate 2 to curve upward in a convex manner, and the substrate 2 can be bent downward. The board can be kept horizontal as the soldering progresses by constantly counteracting the force that causes it to curve convexly.

Furthermore, when using a stepped groove as shown in FIG. 7, it is possible to solder three types of substrates 2 with different thicknesses using one tip groove 11, as shown in FIG. The same applies to the tip groove portion 11.

In the above embodiment, the tip groove portion 11 was explained as being separate from the feed claw wooden body 13, but in this case, the feed claw 9 is not divided into two, and the entire feed claw 9 is pressed against the mounting plate 18 by the feed claw pressing cam. It is clear that the rotation may also be made by rotating it by 20.

Effects The present invention provides an automatic soldering device as described above, in which a feed pawl is configured to grip both sides of a board on which electronic components are mounted and transported by a conveyor by means of a groove at the tip, and the groove at the tip is configured to be rotatable. and a feed pawl rotation drive mechanism that rotates the tip groove of the feed pawl upward as the soldering progresses to generate a force that causes the board to curve upward in a convex manner. The tip groove of the feed pawl is rotated upward in response to the force that causes the board to warp convexly downward, thereby generating a force that causes the board to warp convexly upward, thereby preventing the board from warping. This has the effect of preventing the board from warping during attachment. In addition, since the timing of separation from the molten solder can be made to be the same at every position in the width direction of the board, it is possible to prevent defects in bridges and other soldering and to prevent molten solder from covering the top surface of the board. Soldering has the effect of increasing performance. In addition, since it is not necessary to place a support member for the board in the solder bath, it can be used without any problem with boards with any arrangement of electronic components, and has the effect of improving work efficiency. be.

[Brief explanation of the drawing]

1 to 17 relate to embodiments of the present invention, FIG. 1 is a longitudinal cross-sectional view of a device for preventing warpage of a board, FIG. 2 is a perspective view of the device for preventing warpage of a board, and FIG. 3 is a feed claw pressing FIG. 4 is a partially omitted front view of the feed pawl pressing cam, and FIG. 5 is a partially enlarged longitudinal section showing the mutual relationship between the feed pawl pressing cam, the feeding pawl, and the board. Front view, Figure 6, Figure 7
8 and 8 are side views showing the shapes of the grooves of various tip grooves, FIG. 9, FIG. 10, FIG. 11, FIG. 12, FIG. 13,
Figures 14, 15, and 16 are explanatory diagrams showing the warped state of the board when the rotation angle of the tip groove is gradually increased, Figure 17 is a schematic side view of the automatic soldering device, and Figure 18 is a schematic side view of the automatic soldering device. and Fig. 19 relate to a conventional example, Fig. 18 is a vertical cross-sectional view showing a state in which the board is warped downward as the soldering progresses, and Fig. 19 is a vertical cross-sectional view showing a state in which the board is warped downward in a convex manner as soldering progresses. FIG. 2 is a vertical cross-sectional view at the center in the width direction of the board showing a state where soldering is being performed as soldering process progresses. 1 is an electronic component, 2 is a board, 2b is on both sides, 8 is a board warping prevention device, 9 is a feed claw, IO is a feed type rotation drive mechanism,
Reference numeral 11 indicates a tip groove portion, and reference numeral 17 indicates a conveyor.

Claims (1)

[Scope of Claims] 1. While both sides of a board on which electronic components are mounted and being transported by a conveyor are gripped by a plurality of feed claws, the board is curved downward in a convex manner during soldering. A method for preventing warpage of a substrate, characterized in that the substrate is prevented from warping by rotating the tip groove portion of the feed claw upward to generate a force that causes the substrate to warp upward in a convex manner. 2. A feed claw whose tip groove grips both sides of a board on which electronic components are mounted and is transported by a conveyor, and whose tip groove is configured to be rotatable; 1. An apparatus for preventing warpage of a substrate, comprising: a feed pawl rotation drive mechanism that rotates upward to generate a force that causes the substrate to warp upwardly.