JP2003218511A - Soldering device and printed-wiring board holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a crack and a peeling to soldering sections for electronic parts soldered at the first time in the case of the second flow method when one surface is soldered by a reflow method and another surface by the flow method in a printed-wiring board in which the electronic parts are mounted on both surfaces. <P>SOLUTION: The width of a conveyor 1 is changed in response to the thermal expansion and contraction of the printed-wiring board 7 by the elastic deformation of elastic shafts 4 secured on a soldering device. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering device for soldering electronic parts by passing a printed wiring board over molten solder.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and lighter, printed wiring boards for controlling the equipment have also been required to be made smaller. Electronic components mounted on the printed wiring boards have been changed from insertion type to surface mounting type, and printed wiring boards have also been required. As for the mounting form on a board, a so-called mixed mounting method is also used in which components are mounted from one side to both sides, and an insertion component and a surface mounting component are soldered to the same printed wiring board.

The mixed mounting method is a so-called reflow method, which is a heating device for heating and melting a solder paste printed and applied on a printed wiring board with hot air or infrared rays for soldering.
This is performed by combining a soldering device, which is called a flow method, in which a printed wiring board passes over a bath in which solder is melted to perform soldering.

This will be briefly described. First, a surface of a printed wiring board is mounted on one surface (referred to as a primary surface) of a solder paste by printing a predetermined amount by using a metal mask or the like at a predetermined location. Then, the electronic component can be soldered to the printed wiring board on the primary surface side by heating, melting and cooling the solder paste using a heating device.

Further, an insertion type electronic component is inserted into a fine hole provided in the printed wiring board from the primary surface side, and leads or the like of the electronic component are protruded (a side opposite to the surface coated with the solder paste: The secondary surface (referred to as the secondary surface) was soldered using a soldering device as shown in FIG. Figure 5: Top View of soldering equipment
It shows w.

The soldering apparatus includes a conveyer 41 for conveying the printed wiring board, a pawl 42 provided for holding the printed wiring board, and a conveyor-4.
1, a rotary shaft 43 for operating 1 is provided, and a solder bath 45 is provided for heating solder to fill molten solder, generating a jet of solder with a nozzle or the like, and performing soldering.

In the soldering, the printed wiring board 46 in which the surface mount type electronic component 48 is soldered and the insert type electronic component 47 is inserted is held and conveyed by the pawl 42 provided on the conveyor 41, and the upper surface of the solder bath 45 is fixed. When the printed wiring board 46 passes, the molten solder comes into contact with the back surface (secondary surface) of the printed wiring board 46 and is cooled.

As shown in FIG. 6, when holding the printed wiring board 52, the thickness direction of the printed wiring board 52 around the pawl 51 is restricted by the pawl 51, and the printed wiring board 52 extends in a direction perpendicular to the conveying direction. Are regulated to prevent the printed wiring board from stopping or dropping during the soldering process.

The pawl 51 in FIG. 6 is the pawl 41 in FIG.
Shows the case where is viewed in the conveyance direction of the printed wiring board 52.

[0010]

However, in response to the recent environmental problems, lead-free solder (for example, Sn-A) is used.
g-Cu system), when the electronic component is mounted on the printed wiring board by the conventional soldering apparatus described above, the surface mount type electronic component mounted on the primary surface is peeled off during soldering by the flow method on the secondary surface, There was a problem of poor continuity.

That is, since lead-free solder generally has a higher melting point than conventional lead-containing solder, the set temperature of the solder bath for melting the solder is also high, and lead-free solder is inferior in wettability to lead-containing solder. Therefore, in order to improve the wettability, it is necessary to keep the surface temperature of the printed wiring board high before passing through the solder bath.

Therefore, the surface temperature when the printed wiring board passes over the solder bath becomes higher than in the conventional case, and the printed wiring board expands due to thermal expansion. Tighten this growth 5
Since it is suppressed by 1, the printed wiring board is bent. Due to this bending, if the bonding strength of the surface-mounted electronic component soldered to the primary surface was low, cracks and peeling occurred in the solder part.

[0013]

SUMMARY OF THE INVENTION In order to solve the above problems, according to the present invention, a printed wiring board passes an upper surface of a solder bath filled with molten solder by heating the solder to a temperature equal to or higher than a melting point, and an electronic component is provided. In a device for soldering to a printed wiring board, the width of a conveyor that holds and conveys the printed wiring board provided in the device changes according to the width that changes due to expansion and contraction of the printed wiring board. Is.

According to the present invention, in the soldering of a printed wiring board having electronic components mounted on both sides with lead-free solder, it is possible to prevent the deflection caused by the thermal expansion of the printed wiring board during the soldering of the secondary surface. And 1
It is possible to provide a printed wiring board with high quality reliability without peeling off the electronic component on the next surface.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a printed wiring board passes through the upper surface of a solder bath filled with molten solder by heating the solder to a temperature equal to or higher than the melting point, and the electronic component is printed by the printed wiring board. In the device for soldering, the width of the conveyor for holding and carrying the printed wiring board provided in the device is a soldering apparatus characterized by changing according to the width that changes due to expansion and contraction of the printed wiring board,
Further, the invention according to claim 2 of the present invention is characterized in that a claw for holding the printed wiring board provided in the soldering device and supporting the printed wiring board from the rear side in the traveling direction of the printed wiring board is provided. In the secondary surface soldering, the printed wiring board is prevented from bending due to thermal expansion, and the soldering of the electronic parts on the primary surface is prevented from peeling or cracking. It has the effect that

According to the third aspect of the present invention, the printed wiring board passes through the upper surface of the solder bath filled with the molten solder by heating the solder to the melting point or higher, and the electronic component is soldered to the printed wiring board. In the method, the width of the printed wiring board holding device changes according to the expansion and contraction of the printed wiring board during soldering, and the printed wiring board holding device absorbs the expansion caused by the thermal expansion of the printed wiring board. As a result, there is an effect that the conventional soldering apparatus can perform the soldering with the lead-free solder without peeling off the parts on the primary surface.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In the present invention, when the secondary surface side of a printed wiring board is soldered by a flow method,
It was found that the printed wiring board thermally expands and the printed wiring board warps, causing cracks and peeling in the solder part of the surface-mounted electronic components on the primary surface side, and preventing the printed wiring board from bending due to this thermal expansion. It is something to do.

The soldering device of the present invention is a device for soldering an electronic component to a printed wiring board by passing the printed wiring board through the upper surface of a solder bath filled with molten solder by heating the solder to a temperature above its melting point. It is characterized in that the width of the conveyer which holds and conveys the printed wiring board provided in the apparatus changes according to the width which changes due to expansion and contraction of the printed wiring board.

FIG. 1 shows a top view of a soldering apparatus according to an embodiment of the present invention. The soldering device includes a conveyor -1 for conveying the printed wiring board 7, a pawl 2 for holding the printed wiring board 7 provided thereon, and a rotary shaft 3 and a spring for operating the conveyor -1. The elastic shaft 4 that expands and contracts due to the force is attached to the outer casing 5, the solder is heated to fill the molten solder, and a solder jet is generated by a nozzle or the like to perform soldering 6
Is provided.

The secondary surface of the printed wiring board 7 is soldered by soldering a surface mounting type electronic component 9 such as a semiconductor device or a resistor to the primary surface of the printed wiring board 7 and inserting it into an electrolytic capacitor or a connector. The printed wiring board 7 in which the electronic component 8 is inserted is fixed by the pawl 2, the conveyor -1 is operated by the rotation of the rotating shaft 3, and the printed wiring board 7 is conveyed at a speed of 1 m / min. To improve the printed wiring board 7, the surface of the printed wiring board 7 is heated by a heating device (not shown).
S melted by heating to 0 ° C and further heating at 250 ° C
It is performed by passing the upper surface of the solder bath 6 in which the n-Ag-Cu based lead-free solder is jetted.

In the conventional soldering apparatus, when the printed wiring board passes over the upper surface of the solder bath, the printed wiring board is warmed by the molten solder, and the printed wiring board thermally expands. As shown in FIG. Since the printed wiring board 52 is fixed by the conveyor, the expansion caused by thermal expansion causes the printed wiring board 52 to bend. Due to this deflection, there are problems that cracks may occur in the soldering portion of the surface-mounted electronic component 54 soldered to the primary surface and that the land of the printed wiring board 52 and the soldering portion may separate.

However, in the soldering apparatus of the present invention, when the printed wiring board passes over the upper surface of the solder bath, the printed wiring board is heated and thermally expanded, which causes a force to extend the printed wiring board in the width direction. The stretching force is transmitted to the elastic shaft fixing the conveyor, and the elastic shaft contracts, whereby the thermal stress acting on the printed wiring board is relieved and the printed wiring board can be prevented from bending. As a result, the force exerted on the solder portion of the surface-mounted electronic component soldered to the primary surface side is also alleviated, and it is possible to prevent cracking or peeling of the soldered portion of the surface-mounted electronic component.

Further, the soldering apparatus of the present invention is characterized in that the printed wiring board provided in the soldering apparatus is provided with a pawl for supporting the printed wiring board from the rear side in the traveling direction of the printed wiring board.

FIG. 2 shows a bird's-eye view with a printed wiring board attached to the pawl provided on the conveyor section of the soldering apparatus, and FIG. 3 shows a sectional view taken along the line AA of the soldering apparatus with the printed wiring board attached.

In the soldering apparatus of the present invention, the L-shaped board holding pawl 12 and the printed wiring for holding the printed wiring board 14 are held on the conveyor 11 provided for carrying the printed wiring board 14 to prevent the printed wiring board 14 from falling. There is a movable claw 13 that supports and conveys the board 14 from the rear, and raises the claws 13 of the portion in contact with the rear end surface of the printed wiring board 14 in the direction of conveyance so as to make contact with the other claws. Let it be the same as the bottom of the L-shaped substrate holding tab.

As shown in FIG. 3, the printed wiring board 23 is fixed to the soldering device so that a gap (for example, 3 mm) is formed in the width direction between the L-shaped board holding pawl 21 and the printed wiring board 23, that is, the conveyor. The width of the printed wiring board 23
6 mm larger than the width of the printed wiring board 23, and raising the feeding claw 22 so as to contact the rear end face portion in the feeding direction of the printed wiring board 23.

Conveying is stopped according to the operation of the conveyor 22
Moves to the upper surface of the solder bath by pushing the printed wiring board 23, the solder is attached to the lead of the insertion-type electronic component 24, and the carriage 22 carries the printed wiring board 23 for soldering. 22
When the printed wiring board 23 is removed from the soldering device, is laid down and has the same height as the bottom surface of the L-shaped substrate holding claw 21.

In the conventional soldering apparatus, as described above, when the printed wiring board passes over the upper surface of the solder bath,
Due to the thermal expansion of the printed wiring board, the claws, and the fixing of the conveyor, the printed wiring board is bent, and the soldering part of the surface-mounted electronic component soldered on the primary surface may have cracks or peeling off. Had.

However, in the soldering apparatus of the present invention, a gap is provided between the width of the printed wiring board and the pawl so that the printed wiring board expands in the width direction with respect to the thermal expansion of the printed wiring board. It is possible to prevent bending and prevent cracking or peeling of the soldered portion of the surface-mounted electronic component soldered to the primary surface.

Further, by conveying the printed wiring board from the rear surface while contacting the transportation claws, the printed wiring board is also conveyed according to the speed of the conveyor without slipping of the printed wiring board, and the secondary surface side is inserted. It is also possible to perform soldering on die-type electronic parts without soldering defects.

As described above, in the soldering apparatus of the present invention, when the secondary surface is soldered, the width of the conveyor is changed according to the expansion in the width direction due to the thermal expansion of the printed wiring board, and the fixing portion of the claw is also changed. By holding the printed wiring board with a gap, the printed wiring board can be prevented from bending and soldering can be performed without cracking or peeling of the soldering part on the primary surface side. It is possible to provide a wiring board.

Further, although the present embodiment describes the soldering using the lead-free solder, it has the same effect as the conventional lead-containing solder.

(Second Embodiment) FIG. 4 is a top view of a printed wiring board holding device showing a second embodiment of the present invention.

The printed wiring board holding device of the present invention is a method for soldering electronic components to a printed wiring board by passing the printed wiring board over the upper surface of a solder bath filled with molten solder by heating the solder to a melting point or higher. The width of the printed wiring board changes according to the expansion and contraction of the printed wiring board during soldering.

That is, in FIG. 4, the printed wiring board holding device has an outer frame 3 fixed to the pawl of the soldering device.
3 and a printed wiring board holding claw 31 that holds the printed wiring board 34 are connected by a spring 32 that elastically deforms. When the width of the printed wiring board 34 is extended by thermal expansion, the spring 32 contracts according to the increase in the width.

In the conventional soldering by the soldering device, the printed wiring board is fixed by the claws. Therefore, the printed wiring board is heated and thermally expanded by the heat at the time of soldering, that is, the width of the soldering device is increased. Despite being fixed, a force that extends in the width direction of the printed wiring board works, which causes the printed wiring board to bend and
There is a problem that soldering defects such as cracks and peeling occur in the soldering portion on the next surface side.

However, by fixing the printed wiring board to the printed wiring board holding device of the present invention, and fixing the printed wiring board holding device to the pawl of the soldering device and soldering, the width direction due to thermal expansion of the printed wiring board. The spring 32 contracts and the spacing between the printed wiring board holding claws 31 widens in accordance with the stretching force of the printed wiring board, so that the printed wiring board can be prevented from bending, and soldering failure on the primary surface can also be prevented. It is possible.

Furthermore, by performing soldering with the printed wiring board holding device of the present invention, it is possible to solder printed wiring boards having different widths with the same conveyor width, and to mix printed wiring boards of different models. Soldering is possible, and the soldering productivity is improved.

[0040]

As described above, in the soldering apparatus of the present invention, the conveyor width of the soldering apparatus changes due to the expansion in the width direction due to the thermal expansion of the printed wiring board during soldering, and By fixing the printed wiring board with a gap between the end surface and the pawl of the printed wiring board, it is possible to prevent the printed wiring board from bending and prevent cracks and peeling of the soldered part on the primary surface. Yes,
It is possible to provide a printed wiring board having soldering with high quality reliability.

Further, in the printed wiring board holding device of the present invention, the expansion in the width direction due to the thermal expansion of the printed wiring board can be absorbed by the elastic deformation of the spring provided in the printed wiring board holding device. It is possible to prevent board deflection and to perform highly reliable soldering.In addition, printed wiring boards with different widths can be soldered without changing the conveyor width. It is possible to improve work efficiency.

[Brief description of drawings]

FIG. 1 is a top view of a soldering device according to a first embodiment of the present invention.

FIG. 2 is a conveyor according to the first embodiment of the present invention.
Bird's-eye view of the department

FIG. 3 is a cross-sectional view taken along the line AA of the printed wiring board holding portion in the first embodiment of the present invention.

FIG. 4 is a top view of a printed wiring board holding device according to a second embodiment of the present invention.

FIG. 5 is a top view of a conventional soldering device.

FIG. 6 is a sectional view of a printed wiring board holding portion by a conventional soldering device.

[Explanation of symbols]

1 conveyor Second 3 rotation axes 4 elastic shaft 5 exterior body 6 Solder bath 7 printed wiring board 8 Insertable electronic components 9 Surface mount electronic components 11 Conveyor 12 L type substrate holding 13 Transport 14 Printed wiring board 15 Insertable electronic components 16 Surface mount electronic components 21 L type substrate holding 22 Transport 23 Printed wiring board 24 Insertable electronic components 25 Surface mount electronic components 31 Hold printed circuit board 32 springs 33 outer frame 34 printed wiring board 41 conveyor 42th 43 rotation axis 44 exterior body 45 Solder bath 46 Printed wiring board 47 Insertable electronic components 48 Surface mount electronic components 51st 52 Printed wiring board 53 Insertable electronic components 54 Surface mount electronic components

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Nagashima             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 4E080 AA01 DA04 DB05                 5E319 AA03 AA07 AB01 AC01 CC23                       CD35 CD46 GG20

Claims (3)

[Claims] 1. A device for soldering an electronic component to a printed wiring board by passing the printed wiring board through an upper surface of a solder bath filled with molten solder by heating the solder to a temperature equal to or higher than a melting point, the printed wiring being provided in the device. A soldering device characterized in that the width of a conveyor that holds and conveys a board changes according to the width that changes due to expansion and contraction of the printed wiring board. 2. An apparatus for soldering an electronic component to a printed wiring board by passing the printed wiring board through an upper surface of a solder bath filled with molten solder by heating the solder to a melting point or higher, the printed wiring being provided in the apparatus. A soldering device having a claw for holding the plate and supporting the plate from the rear in the traveling direction of the printed circuit board. 3. A method of soldering an electronic component to a printed wiring board by passing the printed wiring board through the upper surface of a solder bath filled with molten solder by heating the solder to a melting point or higher, the printed wiring board being soldered. A printed wiring board holding device whose width changes according to expansion and contraction of the printed wiring board.