JP2000114707A - Soldering method of printed board and jet soldering bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stick proper quantities of melted solder corresponding to the lead shapes of different types of electronic components on one printed board and improve the quality and reliability of soldering. SOLUTION: An escape hole 10B is formed in an advance nozzle part 10A. The escape hole 10B is formed in order to increase the solder flow angle θA of a peel-back point PBP from the surface of a printed board 84. The angle of a guide plate 11 is automatically adjusted while the printed board 84 is conveyed. With this constitution, as melted solder 95 at the peel-back point PBP escapes into the hole 10B, the head of the melted solder 95 is changed and the shape of jet wave is adjusted. That is, the jet wave of the melted solder can be changed so as to correspond to the positions of the leads where solder bridges are to be avoided and to the positions of the leads where large quantities of melted solder are to be stick respectively on the same printed board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for soldering a printed circuit board on which a printed circuit board on which electronic components are mounted is conveyed toward a solder jet nozzle and soldered, and a jet solder bath.

[0002]

2. Description of the Related Art In general, a method of soldering an electronic component (for example, QFP) mounted on a printed circuit board used for a consumer device, an industrial device, or the like is as follows.
One is the dipping method (dip method). This dip method uses a jet solder bath to contact the jetted molten solder with a multi-legged electronic component having a plurality of leads and a printed board with a high mounting density.

For example, as shown in FIG. 7, electronic components 80 and 82 such as dexlet components and high-density chip components used in a television or the like are mounted on a single printed circuit board 84. That is, the holes 85 are formed in the printed circuit board 84.
Are formed, and the electronic components 80 and 82 are formed in the holes 85.
Are inserted. Then, as shown in FIG. 8, after the insertion, the tips of the leads 81 and 83 project from the lower surface of the printed circuit board 84.

The leads 81 and 83 have different shapes and different lengths. That is, the tip of the lead 81 is V-shaped and formed in a plate shape. The lead 83 has a columnar shape and is shorter than the length of the lead 81.

On the other hand, as shown in FIG. 9, the automatic soldering apparatus 86 employing the above-described dip method includes a flux 9 on a printed circuit board 84 from a downstream side to an upstream side.
A fluxer 92 for applying 3 and a fluxer 92
The printed circuit board 84 coated with the flux 93 by 10
A pre-heater 94 which is heated to about 0 degrees to make it optimal for soldering, and a first jet solder in which molten solder 95 is blown up from a jet nozzle 96A and a printed circuit board 84 is brought into contact with the surface of this jet to perform soldering. A bath 96, a second jet solder bath 96 having a jet nozzle 98 for blowing up the molten solder 95, and the printed circuit board 8 after soldering.
4 is provided.

The automatic soldering device 86 is provided with a transfer device 91 for transferring the printed circuit board 84 from the downstream side to the upstream side of the automatic soldering device 86. The transfer device 91 is constituted by a belt conveyor or the like.

Here, the printed board 84 and the leads 81
The adhesion amount of the molten solder 95 to the second and the third soldering bath 96 is determined by the outlet point (peelback point) of the jet in the second bath 96.
Fluctuates due to the flow of the molten solder 95. Also,
In order to perform soldering properly, it is common to set the relative angle between the printed board 84 and the jet surface of the molten solder 95 appropriately and to reduce the relative speed between the printed board 84 and the jet stream of the molten solder 95. It is good to be.

[0008]

When electronic components 80 and 82 having different shapes and lengths of the leads 81 and 83 are mounted on one printed circuit board 84,
When the printed circuit board 84 is soldered by the automatic soldering device 86, the amount of the molten solder 95 corresponding to one of the leads 81 or 83 is obtained.

More specifically, as shown in FIG. 10, when the amount of the molten solder 95 is made to correspond to the lead 83,
The bonding strength to the lead 81 after soldering is reduced. That is, the amount of the molten solder 95 attached to the lead 81 is reduced (the height of the fillet shape is reduced). For example, when an impact is applied to the printed circuit board 82 after soldering, the solder attached to the lead 81 may fall. There is a problem.

[0010] On the other hand, contrary to the case shown in FIG.
There is a problem that the molten solder 95 attached to the leads 83 becomes excessive and a bridge is generated.

When only one electronic component 80 having the same shape of the lead 81 is mounted on one printed circuit board 84, a jet nozzle 98 such that the amount of molten solder 95 corresponding to the lead 81 is provided. The above arrangement does not cause the above problem. On the other hand, one printed circuit board 8
In the case where only the electronic component 82 of the lead 83 having the same shape is mounted on the lead 4, the above-described problem occurs due to disposing the jet nozzle 98 such that the amount of the applied molten solder 95 corresponds to the lead 83. Absent.

That is, the above-mentioned problems occur because
This is a case where the shapes, lengths, and lead densities (the number of leads existing per unit area) of the leads 81 and 83 of the electronic components 80 and 82 mounted on a single printed circuit board 84 are different. Therefore, in this case, the same amount of the molten solder 95 is attached to the leads 81 and 83 having different shapes and lengths, and it is not possible to attach an appropriate amount of the molten solder 95 to the leads 81 and 83, respectively. A point occurs.

In view of the above facts, the present invention improves the quality and reliability of solder by attaching an appropriate amount of molten solder corresponding to the lead shape of different types of electronic components mounted on one printed circuit board. An object of the present invention is to provide a method of soldering a printed circuit board and a jet solder bath.

[0014]

According to a first aspect of the present invention, there is provided a method of soldering a printed circuit board, the method comprising the steps of: transferring a printed circuit board on which electronic components are mounted toward a jet nozzle for soldering; A method of attaching the jet nozzle by moving an adjusting means arranged so as to be continuous with an advance nozzle portion at an end of the jet nozzle on an advance side of the printed circuit board with respect to molten solder jetted from the jet nozzle. The molten solder at the exit point of the jet where the printed circuit board is separated from the molten solder jetted from the nozzle is released to the jet solder bath via escape means provided in the advance nozzle portion, and the head relative to the printed circuit board is printed. The automatic adjustment is performed during the transfer of the substrate.

According to the method of soldering a printed circuit board according to the first aspect of the present invention, by moving the adjusting means, the jet wave at the exit point of the jet where the printed circuit board is separated from the molten solder jetted from the jet nozzle. Is automatically adjusted and changed during the transfer of the printed circuit board.

That is, according to the method of soldering a printed circuit board according to the first aspect of the present invention, the molten solder at the outlet of the jet is released to the jet solder bath via the escape means by moving the adjusting means. Therefore, according to the method of soldering a printed circuit board according to claim 1 of the present invention, the head relative to the printed circuit board is automatically adjusted during the transfer of the printed circuit board. The jet wave of the molten solder can be changed so as to correspond to a portion where it is desired not to generate a bridge and a portion where a large amount of molten solder is to be attached.

Therefore, according to the printed circuit board soldering method according to the first aspect of the present invention, an appropriate amount of molten solder corresponding to the lead shapes of different types of electronic components mounted on one printed circuit board is attached. So you can
The quality and reliability of solder after soldering different types of electronic components to one printed circuit board are improved.

The jet solder bath according to claim 2 of the present invention comprises:
A jet solder bath for carrying a printed circuit board on which electronic components are mounted toward a solder jet nozzle for soldering, wherein an end of the jet nozzle on an advancing side of the printed board with respect to molten solder jetted from the jet nozzle. A movable adjusting means for adjusting a head of the molten solder with respect to the printed circuit board, which is disposed so as to be continuous with the advance nozzle portion provided in the portion, and disposed in the advance nozzle portion;
Escape means for letting out the molten solder into the jet solder bath, and controlling the movement of the adjusting means so that the molten solder flows through the escape means at the exit point of the jet where the printed circuit board separates from the molten solder. Control means for automatically adjusting the drop to the printed circuit board during the transfer of the printed circuit board to the solder bath.

According to a third aspect of the present invention, there is provided a jet solder bath,
In the invention described in claim 2, the adjusting means rotates the guide plate via the guide plate, a guide shaft which supports the guide plate, and a support shaft which supports the guide plate. And the control means is a computer connected to the motor while the escape means is an escape hole, and the molten solder is rotated from the escape hole to the jet solder bath by rotating the guide plate. It is characterized by escape.

[0020] The jet solder bath according to claim 4 of the present invention comprises:
The invention according to claim 3, wherein the advancing nozzle portion is formed of a member separate from the jet nozzle, and the advancing nozzle portion and the guide plate can be moved in a transport direction of the printed circuit board. Features.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a method for soldering a printed circuit board and a jet solder bath according to the present invention will be described with reference to FIGS. Note that the same components as those of the related art shown in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted. The present embodiment corresponds to claims 1 to 3.

The structure of the second jet solder bath 99 shown in FIG. 1 relating to the jet nozzle 98 will be described with reference to FIG. The jet port 20 of the jet nozzle 98 is provided with a pair of nozzle plates 22 and 2
4, nozzle side plates 26 arranged on both sides of these nozzle plates 22 and 24 (only one is shown, the other is not shown)
It is composed of

As shown in FIG. 3, a rear former 10 disposed horizontally is integrally formed at the tip of the nozzle plate 24 (the side where the printed circuit board 84 advances) toward the downstream side. The rear former 10 is integrally formed with an arc-shaped advance nozzle portion 10A centered on a support shaft 12 described later.

As shown in FIG. 2, an escape hole 10B as escape means is formed in the advance nozzle portion 10A, and the escape hole 10B has a substantially rectangular shape slightly smaller than the size of the advance nozzle portion 10A. . That is, the escape hole 10B is
It is formed to be slightly smaller than the size obtained by connecting the outlines of the advance nozzle portion 10A, and substantially along the outline of the advance nozzle portion 10A.

Here, the escape nozzle 10A is provided with an escape hole 10
B is provided as shown in FIG.
This is to increase the angle θA of the peel back point PBP (see FIG. 5) (that is, the solder flow angle) with respect to the surface (surface facing the jet port 20). That is, most of the molten solder 95 on the rear former 10 flows to the second jet solder bath 99 through the escape hole 10B, so that the molten solder 95 leaving the printed circuit board 84 flows toward the upstream side of the automatic soldering device 86. .

The length of the escape hole 10B in the width direction (the direction orthogonal to the direction in which the printed board 84 is transported) is longer than the length corresponding to the range of the leads 81 or 83 provided on the printed board 84. It is set as follows. The length of the escape hole 10B in the vertical direction is long so that the solder flow angle θA can be largely changed.

Guide plate 11 constituting a part of the adjusting means
Is rotatably supported by a support shaft 12 which constitutes a part of the adjusting means so as to be continuous with the advance nozzle portion 10A. That is, the guide plate 11 and the support shaft 12 are mounted so as to rotate integrally, and when the guide plate 11 rotates about the support shaft 12, the distal end 11A of the guide plate 11 is
It moves in a state of contact along A. In this case, as shown in FIG. 3 and FIG.
Is prevented from dropping from the leading end 11A and the advance nozzle portion 10A.

As shown in FIG. 2, a motor 14 constituting a part of the adjusting means is connected to the support shaft 12,
When the motor 14 rotates, the support shaft 12 rotates. That is, a gear 28 is attached to one end of the support shaft 12, and the motor 14 is disposed at a portion facing the gear 28. The motor gear 15 of the motor 14 and the gear 2
8 are engaged with each other, and the rotation of the motor 14
2 rotates, and the guide plate 11 also rotates.

A guide plate 29 is suspended from the spindle 12, and the tip of the guide plate 29 is immersed in the molten solder 95 of the second jet solder bath 99 (see FIG. 1) and flows down from the nozzle plate 22. This prevents the molten solder 95 from jumping.

The tip of the nozzle plate 22 is bent in a substantially arc shape, and the end of this tip is in the second jet solder bath 99.
The molten solder 95 immersed in the molten solder 95 and flowing down from the nozzle plate 22 is prevented from jumping.

A computer 16 is connected to the motor 14 as a control means. Based on a control signal from the computer 16, the motor 14 is automatically controlled so that the motor 14 rotates a predetermined amount in the forward and reverse directions. The computer 16 has information on the mounting positions of the electronic components 80 and 82 from which the leads 81 and 83 having different shapes and lengths previously arranged on the printed circuit board 84 shown in FIGS. Information "). The board information includes, for example, electronic components 80 and 82
The control data of the auto insertion (AI) to be mounted on the computer 4 may be used as it is, and the control data may be input to the computer 16.

That is, the leads 8 for the printed circuit board 84
The position information (board information) of 1 and 83 is
Of the molten solder 95 at the peel back point PBP (see FIGS. 3 and 5), that is, the molten solder 9 based on the board information.
5 (specifically, the printed circuit board 84 and the leads 8
1 and 83).

In this case, the transport direction of the printed circuit board 84 (the direction of arrow DP in FIG. 6) is stored in the memory of the computer 16 in advance, and which electronic component 80 or 82 first determines the peel back point PBP. Information on, for example, time of passing is input to the computer 16.

In the case of this embodiment, the electronic component 82 (ie, the lead 83 shown in FIG. 3) first passes through the peel back point PBP, and thereafter, the electronic component 80 (ie, FIG. 5).
Lead 81) passes through the peel back point PBP. Then, the computer 16 drives the motor 14 to rotate the guide plate 11 by a predetermined amount in accordance with the passage timing of the electronic component 80 or 82 with respect to the peel back point PBP.

Next, the operation of the present embodiment will be described. First, the direction of the printed board 84 shown in FIG. 6 is set so that the electronic component 82 faces the downstream side of the automatic soldering device 86, that is, the transport direction (the direction of arrow DP in FIG. 6). Then, as shown in FIG. 1, when the printed circuit board 84 passes through the first jet solder bath 96 and reaches the jet nozzle 98 of the second jet solder bath 99 as shown in FIG. The printed circuit board 84 comes into contact with the wiring circuit conductor (not shown) of the printed circuit board 84 and the leads 83A.
Molten solder 84 adheres to the substrate.

In this case, the position of the guide plate 11 is determined based on the board information previously input to the computer 16, and the jet wave of the molten solder 95 at the peel back point PBP is applied to the electronic component mounted on the printed board 84. Corresponding to the leads 83 (see FIG. 3), a suitable amount of molten solder 95 adheres to the leads 83 (see FIG. 6).

That is, as shown in FIG.
Are kept horizontal. Note that the tip of the lead 83 that has passed through the peel back point PBP is separated from the molten solder 95 returned from the peel back point PBP. Note that the computer 16 controls the jet nozzle 9
The jet flow rate of the molten solder 95 in FIG. 8 is preset so as to always be in the state shown in FIG.

Next, as shown in FIG.
When the electronic component 80 (see FIG. 7) mounted on the computer 4 is located immediately before the peel back point PBP, the guide plate 1 is set based on the board information input to the computer 16 in advance.
1 in the counterclockwise direction (CCW direction in FIG. 5)
9 correspond to the leads 81 of the electronic component 80.

That is, as shown in FIG. 4, when the guide plate 11 rotates, the escape hole 10B of the advance nozzle portion 10A is opened (the tip 11A of the guide plate 11 is located at or below the escape hole 10B). ). Therefore, in the present embodiment, the molten solder 95 jetted out
B escapes to the second jet solder bath 99, and the solder flow angle θ
A becomes a substantially right angle.

In this embodiment, the solder flow angle θ
A is larger than that of FIG. 3 and the lead 81 portion (or 83 portion) corresponding to the peel back point PBP
The molten solder 95 is controlled so as to reduce the flow rate of the molten solder 95 on the jet surface of the molten solder 95. As a result, when the lead 81 or 83 is separated from the molten solder 95, the molten solder 95 is pulled and pulled between the leads 81 or 83. Don't get in between).

Also, since the molten solder 95 hangs substantially perpendicularly to the axis of the lead 81, a large amount of the molten solder 95 adheres to the lead 81 along the axis (see FIG. 6). That is, according to the present embodiment, since a high fillet having a good fillet shape and a high height can be formed, the molten solder 95 to the lead 81 is high-fillet-joined, and a high-fillet joint portion can be formed.

Therefore, according to the present embodiment, the lead 81
Becomes a high fillet joint, so that the life of the solder is prolonged. Specifically, it is preferable to apply the present invention to a lead portion where a large amount of molten solder 95 such as FBT (fly back transformer) needs to adhere.

The molten solder 95 flowing down from the escape hole 10B returns to the second jet solder bath 99, and is formed by the rear former 10 (including the advance nozzle portion 10A), the guide plate 11, and the nozzle plate 24 on the printed circuit board 84 side. Covered not to jump to. Also, as shown in FIG.
Most of the jetted molten solder 95 flows to the second jet soldering bath 99 through the escape hole 10B, but is also split to the guide plate 11 and the guide plate 29 side.

Further, in this embodiment, the peel back point PBP in the transport direction of the printed circuit board 84
Is changed, as shown in FIG. 6, the leads 8 of the electronic component 80 mounted on the printed circuit board 84 are changed.
In response to 1, the appropriate amount of molten solder 95 adheres to the lead 81. That is, in the present embodiment, even when various types of electronic components are mounted on one printed circuit board 84, the molten solder 95 is formed in accordance with the lead shapes of these electronic components.
Can be attached.

Further, since the molten solder 95 which is jetted down by the tip 11A of the guide plate 11 flowing down flows into the escape hole 10B, the drop of the molten solder 95 at the peel back point PBP becomes larger than that shown in FIG. Solder 9
5, the velocity of the jet surface becomes slow. Therefore, even in the case of the lead 81 longer than the length of the lead 83, the lead 8
When the tip of 1 is separated from the molten solder 95 in which the peel back point PBP is refluxed, the molten solder 95 is not drawn in between the leads 81.

In this embodiment, since the solder flow angle θA is automatically adjusted by the motor 14 and the computer 16 during the transfer of the printed circuit board 84, the drop of the molten solder 95 at the peel back point PBP changes, and the jet wave Shape can be adjusted.

That is, in this embodiment, the peel back point PBP in the transport direction of the printed circuit board 84
Changes during the transfer of the printed circuit board 84,
Even when the shapes, lengths, and lead densities of the leads 81 and 83 of the electronic components 80 and 82 mounted on a single printed circuit board 84 are different, an appropriate amount of molten solder 95 corresponding to the leads 81 and 83 respectively adheres.

Further, in this embodiment, in the leads 81 and 83 on the same printed circuit board 84, the molten solder 95 is formed so as to correspond to a portion where no bridge is to be generated and a portion where a large amount of the molten solder 95 is to be attached. Jet wave can be changed.

That is, according to this embodiment, the amount of the molten solder 95 adhered to the leads 81 or 83 is not excessive, and the occurrence of bridges is prevented.
The amount of the molten solder 95 adhering to the solder can be reduced, and the bonding strength to the lead 81 or 83 after soldering can be increased.

Therefore, according to this embodiment, different types of electronic components 80 mounted on one printed circuit board 84
Or an appropriate amount of molten solder 95 corresponding to the shape of the lead 81 or 83 of the electronic component 82 or 82 can be attached, so that the quality and reliability of the solder after soldering different types of electronic components 80 or 82 to one printed circuit board 84 The performance is improved.

As an example corresponding to claim 4 of the present invention, although not shown, the portion of the advance nozzle portion is formed of a member separate from the rear former 10 of the nozzle plate 24 of the jet nozzle 98, and Part and guide plate 11
Can be moved in the transport direction of the printed circuit board 84 (the direction of arrow DP in FIG. 6).

When it is desired to change the position of the peel back point PBP with respect to the transport direction of the printed circuit board 84, the adjusting means including the advance nozzle portion and the guide plate 11 is slid. Therefore, according to the above configuration, since the adjusting means including the portion of the advance nozzle portion and the guide plate 11 is slidable, the position of the peel back point PBP with respect to the printed board 84 can be arbitrarily changed.

In this embodiment, two types of electronic components 80 and 82 are mounted on the printed circuit board 84 described in each of the above-described embodiments.
The same operation and effect can be obtained even when mounted on a single printed circuit board 84. In this case, it is necessary to input the board information of these electronic components to the computer 16.

The adjusting means of the above embodiment has a rotary structure for rotating the guide plate 11, but the adjusting means of the present invention changes the head of the molten solder 95 at the peel back point PBP to change the shape of the jet wave. For example, an elevating structure for elevating and lowering the guide plate 11 may be used as long as the height can be adjusted.

Further, the shape of the escape hole 10B in the above-described embodiment is substantially rectangular, but is not limited to this.
May be formed. That is, the escape means of the present invention can adjust the shape of the jet wave of the molten solder 95 by allowing the molten solder 95 at the peel back point PBP to escape into the second jet solder bath 99 via the escape means. The configuration is not limited.

[0056]

As described above, according to the present invention, 1
Since a suitable amount of molten solder corresponding to the lead shape of different types of electronic components mounted on a single printed circuit board can be attached, the quality of solder after soldering different types of electronic components to one printed circuit board and Reliability is improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of an automatic soldering apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the vicinity of a jet nozzle of a second jet solder bath shown in FIG.

FIG. 3 is a cross-sectional view showing a state in which a printed circuit board passes through the jet nozzle shown in FIG.

4 is a perspective view of the vicinity of the jet nozzle in a state where a guide plate of the jet nozzle shown in FIG. 3 is rotated.

FIG. 5 is a cross-sectional view showing a state where a guide plate of the jet nozzle shown in FIG. 4 is rotated.

FIG. 6 is a cross-sectional view showing a soldering state of a printed circuit board when soldering is performed by the automatic soldering apparatus shown in FIG.

FIG. 7 is a cross-sectional view showing a state in which different types of electronic components are mounted on a printed circuit board.

8 is a perspective view showing a lead shape of the electronic component shown in FIG.

FIG. 9 is a schematic view of an automatic soldering apparatus according to a conventional example.

10 is a cross-sectional view illustrating a soldering state of a printed circuit board when soldering is performed by the automatic soldering apparatus illustrated in FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Rear former (member which comprises a part of jet nozzle) 10A Exit nozzle part 10B Escape hole (escape means) 11 Guide plate (adjustment means) 12 Support shaft (adjustment means) 14 Motor (adjustment means) 16 Computer (control means) 80, 82 Electronic component 81, 83 Lead 84 Printed circuit board 95 Molten solder 98 Jet nozzle 99 Second jet solder tank DR Transport direction PBB Peel back point (exit point of jet) θA Solder flow angle

Claims (4)

[Claims] 1. A method for soldering a printed circuit board on which a printed circuit board on which electronic components are mounted is transported toward a solder jet nozzle for soldering, wherein the printed board is soldered to a molten solder jetted from the jet nozzle. By moving the adjusting means arranged so as to be continuous with the advance nozzle portion at the end of the jet nozzle on the advance side, the exit point of the jet at which the printed board separates from the molten solder jetted from the jet nozzle is removed. Soldering the printed circuit board, wherein the molten solder is released to a jet solder bath via a release means provided in the advance nozzle portion, and a head relative to the printed circuit board is automatically adjusted during the transfer of the printed circuit board. Method. 2. A jet solder bath for transferring and soldering a printed circuit board on which electronic components are mounted toward a jet nozzle of solder, the jet solder tank being provided on an advancing side of the printed circuit board with respect to molten solder jetted from the jet nozzle. Movably adjusting means arranged to be continuous with the advance nozzle portion provided at the end of the jet nozzle and adjusting a drop of the molten solder with respect to the printed circuit board; provided at the advance nozzle portion; Escape means for letting out the molten solder into the jet solder bath; controlling the movement of the adjusting means so that the molten solder at the exit point of the jet where the printed circuit board is separated from the molten solder is jetted through the escape means. Control means for automatically adjusting the drop to the printed circuit board during the transfer of the printed circuit board to the solder bath. Jet solder bath characterized. 3. The adjusting means comprises a guide plate disposed continuously to the advance nozzle portion, a support shaft for supporting the guide plate, and a motor for rotating the guide plate via the support shaft. The escape means is configured as an escape hole, and the control means is a computer connected to a motor, and the molten solder is escaped from the escape hole to the jet solder bath by rotating the guide plate. The jet solder bath according to claim 2, wherein 4. The advance nozzle section is formed of a member separate from the jet nozzle, and the advance nozzle section and the guide plate are movable along a direction in which the printed circuit board is transported. Item 4. A jet solder bath according to Item 3.