JP3628490B2 - Soldering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a soldering apparatus for flow soldering a soldered wiring board such as a printed wiring board.
[0002]
[Prior art]
As is well known, a flow soldering method is generally used to solder a lead wire to a land of a printed wiring board in an electronic component or the like with a lead wire. At that time, the superiority or inferiority of the soldered state is determined by the fillet shape of the solder formed between the land and the lead wire.
[0003]
6A and 6B are diagrams illustrating the formation of fillets when performing flow soldering. FIG. 6A is a side view illustrating the formation factors, and FIGS. 6B and 6C illustrate the formation of fillets. It is a sectional side view to explain.
[0004]
In these drawings, 1 is a printed wiring board, 2 is a land, 3 is an electronic component, 4 is a lead wire of the electronic component 3, 5 is a conveyor, 6 is a carry-in side of the printed wiring board 1, and 7 is a carry-out side. , 11 molten solder, 12 the jet flow, 13 is the peel back point, 14 fillets, a is the transport direction of the printed wiring board _1, V F, the _{V R} is spaced flow rate of the molten solder 11.
[0005]
The shape of the fillet 14 shown in FIGS. 6 (b) and 6 (c) is made of solder because it is necessary to withstand stress due to temperature cycle and stress due to vibration and to maintain mechanical connection and electrical connection for a long period of time. Thickness is better. That is, the shape of the fillet 14 in FIG. 6B has a larger amount of solder adhesion than the shape of the fillet 14 in FIG. In particular, after the Product Liability Act is enforced, the improvement of the shape of the fillet 14 is considered as an important factor.
[0006]
As a typical example of the flow soldering apparatus, there is a technique disclosed in Japanese Patent Laid-Open No. 8-288634. This soldering device technology can secure a sufficient contact time even when the height of the jet wave is low, and can perform good soldering. Furthermore, the angle between the distance at the peelback point and the peelback By adjusting the molten solder separation flow rate at the point, a thick fillet can be formed while eliminating the bridge phenomenon and the icicle phenomenon.
[0007]
The gist of the technique disclosed in JP-A-8-288634 is that a barrier plate is provided between the nozzle portion and the tray portion, and the height of the barrier plate can be adjusted. Thus, by adjusting the height of the weir plate, it becomes possible to match the inclination of the jet wave with the transport elevation angle of the printed wiring board, and the guide plate provided in the tray portion, that is, the overflow weir and the aforementioned By adjusting the relative height with the weir plate, it is possible to adjust the separation angle and the separation flow rate of the molten solder at the peelback point.
[0008]
Of course, it is also possible to adjust the flow rate of the molten solder at the peel-back point by adjusting the flow rate of the pump that supplies the molten solder to the nozzle. By adjusting together, it is possible to set the target separation angle and separation flow velocity at the peelback point.
[0009]
On the other hand, as shown in FIGS. 6B and 6C, the main factor that defines the shape of the fillet 14 when forming the fillet 14 is the separation angle θ ₁ of the molten solder 11 at the peel-back point 13 shown in FIG. Or the separation flow velocity V _F at the peel back point 13. Then, a further it conveying elevation theta ₁₁ of the printed wiring board 1 that defines secondarily and its conveying speed V _C and the like. In conclusion, there are a force F _V acting in a direction perpendicular to the land 2 of the printed wiring board 1 and a force F _C acting in a direction parallel to the land 2, and the force F _V is the force of gravity and the molten solder 11. The separation direction, that is, the separation angle θ ₁ and the separation flow velocity V _F are defined.
[0010]
The force F _V has an action of increasing the thickness of the fillet 14, and the force F _C has an action of reducing the thickness of the fillet 14. Therefore, in the actual soldering operation, seeking an appropriate proportion of the force F _V and the force F _C in accordance with the pattern design condition and mounting state of the printed wiring board 1. That is, the separation angle θ ₁ and the separation flow velocity V _F which are the main factors for forming the fillet 14 are determined.
[0011]
Incidentally, large spacing angle theta ₁ in peel back point 13, when the movement of the peel-back point 13 is little, it possible to eliminate the solder bridge also while increasing the solder adhesion amount by increasing the force F _V become able to. That is because it is possible to withdraw the bridge solder by further increase of the force F _V.
[0012]
Incidentally, the force F _C is defined in the conveying speed V _C and the detaching angle theta ₁ and conveying elevation theta ₁₁ of the printed wiring board 1, or to increase the conveyance elevation angle theta _11, or by decreasing the spacing angle theta ₁ and spaced flow rate increases be to close the V _F and the conveying speed V _C. That is, in the latter state, the peel-back point 13 is stretched and moved in the transport direction A, and thereafter, a phenomenon occurs in which the peel-back point 13 rapidly returns in the direction opposite to the transport direction A. We produce a force _{F C.}
[0013]
[Problems to be solved by the invention]
However, the main factor defining the force F _V in the publication of the art, a nozzle (Fig. 6, not shown) is guided by a guide plate or the like ejected molten solder 11 forming the jet flow 12 is not shown from the free fall only spaced flow velocity V _F and the gravity of the molten solder 11. Therefore, it is impossible to force F _V to large forces more.
[0014]
An object of the present invention, beyond the limits of the action force due to free fall and gravity of the molten solder, by to be able to further generate a large force F _V, solder adhesion amount for forming the fillet than a conventional It is to enable soldering without causing a solder bridge while further increasing the number. Accordingly, it is possible to improve the reliability of the soldered portion and enable high-quality soldering that does not cause a soldering failure such as a solder bridge.
[0015]
[Means for Solving the Problems]
The soldering apparatus according to the present invention is characterized in that the molten solder that detaches from the peel back point is forcibly discharged by a suction action, and this forced discharge limits the speed limit due to the free fall of the molten solder. Beyond that, the separation speed of the molten solder at the peel back point can be increased.
[0016]
This makes it possible to further increase the force F _V acting on the lands of the soldered circuit board, it is possible to achieve both elimination of growth and solder bridging of solder deposition amount of the fillet.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention can be implemented in the following forms.
[0018]
In soldering apparatus to supply molten solder to a nozzle by a pump to form a jet flow of molten solder to the mouthpiece, performing soldering by contacting the the jet flow and the printed wiring board, the vicinity of the mouthpiece Further, forcible discharging means for forcibly sucking the molten solder ejected from the blowing port is provided.
[0019]
Thereby, the separation speed of the molten solder at the peel back point can be further increased beyond the limit of the falling speed of the molten solder due to the free fall of the molten solder. And it becomes possible to achieve both an increase in the amount of solder attached to the fillet and elimination of the solder bridge.
[0020]
Specifically, the forced discharge means for the molten solder is configured to use a venturi channel having a suction action.
[0021]
The venturi flow channel is a portion in which the pressure is reduced in the expanded portion by gradually expanding the cross-sectional area of the flow channel and then rapidly expanding. Therefore, when another flow path is connected to the low pressure portion, it becomes possible to positively discharge from the flow path.
[0022]
Therefore, by using such a Venturi flow path, it becomes possible to forcibly discharge the molten solder.
[0025]
【Example】
Next, an embodiment of the soldering apparatus according to the present invention will be specifically described.
[0026]
[First embodiment]
FIG. 1 is a side sectional view of a main part showing a first embodiment of the present invention, showing a jet nozzle portion of a soldering apparatus, and the same reference numerals as those in FIG. 6 denote the same or corresponding parts. The soldering apparatus of FIG. 1 supplies molten solder to a nozzle body 21 by a pump 25 which is a means for supplying molten solder 11 which is heated by a heater (not shown) and is in a molten state, and jets into a nozzle 22 of the nozzle body 21. The soldering apparatus which forms the wave 12 is shown, and the molten solder 11 is accommodated in the solder tank which is not shown in figure. In FIG. 1, the nozzle body 21, which is the gist of the invention, and its vicinity are shown, and the other components described above are omitted or simplified.
[0027]
In this way, the molten solder 11 supplied to the nozzle body 21 by the pump 25 is ejected from the blowing port 22 to form the jet wave 12, and the front jet guide plate 23 on the carry-in side 6 and the rear jet on the carry-out side 7. It flows down along the guide plate 24 to the carry-in side 6 and the carry-out side 7 of the printed wiring board 1 and returns to a solder tank (not shown).
[0028]
The printed wiring board 1 is conveyed at an elevation angle θ ₁₁ (usually about 0 to 5 °) by two parallel conveying conveyors 5 that hold both end portions thereof, and the lower surface (soldered) is applied to the jet wave 12. Soldering is performed by supplying the solder to the soldered portion on the lower surface.
[0029]
In the first embodiment of FIG. 1, a venturi portion (corresponding to a venturi tube) 31 is formed on the peel back point 13 side as a forced discharge means for the molten solder 11 in the vicinity of the peel back point 13. That is, the venturi forming plate 32 and the nozzle body 21 form a venturi flow path 33 having a suction action, and a jet wave guided by the rear jet guide plate 24 to the enlarged portion of the venturi flow path 33, that is, the venturi portion 31. Twelve rear jets are configured to merge. Therefore, the molten solder 11b flowing down from the peel back point 13 is discharged by the suction action of the molten solder 11a flowing in the venturi flow path 33 in addition to the natural flow.
[0030]
The venturi forming plate 32 forms the venturi portion 31 so as to guide the molten solder 11 flowing through the nozzle 21 to the venturi flow path 33 and return to the solder tank (not shown), and the cross-sectional area of the venturi flow path 33 flows. After being gradually reduced in the direction, it is configured to expand.
[0031]
Therefore, a force that is sucked and discharged by the molten solder 11a flowing through the venturi flow path 33 acts on the molten solder 11b that flows away from the peel-back point 13 by the rear jet guide plate 24, and the separation speed V _I has a higher speed than in the case of free fall. Spacing angle of the molten solder 11 in the peel-back point 13 in this case is theta _1.
[0032]
The separation speed V ₁ of the molten solder 11 is further increased as compared with the case of free fall (free flow) due to the venturi effect, and is thus formed on the soldered portion of the printed wiring board 1 shown in FIG. More molten solder 11 adheres to the fillet 14 and no bridging phenomenon due to the molten solder 11 occurs.
[0035]
FIG. 2 is a reference example, not an embodiment, in which a discharge pump 41 is provided in the rear jet portion of the peelback point 13, and a discharge flow path 42 is formed between the rear jet guide plate 24 and the nozzle body 21. The discharge channel 41 is provided in the discharge channel 42. By adjusting the forced discharge flow rate of the discharge pump 41, the separation flow velocity V1 of the molten solder 11 separated from the peelback point 13 can be adjusted. However, a separate pump 41 is required as compared with the embodiment.
[0038]
3 is also a reference example, not an embodiment, and a pump 25 for supplying the molten solder 11 to the nozzle body 21 is also used for forced discharge, and is formed between the rear jet guide plate 24 and the nozzle body 21. The discharged recirculation path 43 is guided to the suction port 26 side of the pump 25. As shown in FIG. 3, a valve body 45 that rotates around the hinge 45 is provided in the discharge reflux path 43 so that the flow rate of the molten solder 11 flowing through the discharge reflux path 43 can be adjusted. Yes. However, the molten solder returns to the pump without returning to the solder bath (not shown).
[0040]
[ Second Embodiment]
FIG. 4 is a side sectional view of a main part showing a second embodiment of the present invention, showing a jet nozzle portion of a soldering apparatus, and the same reference numerals as those in FIG. 1 denote the same or corresponding parts. Further, similarly to the first embodiment of FIG. 1, the nozzle body 21 which is the gist of the invention and its vicinity are shown.
[0041]
Soldering apparatus of the second embodiment, is provided with a variety of regulatory mechanisms soldering apparatus of the first embodiment. Basically, in order to form the venturi portion 51 as in the first embodiment, the venturi forming plate 52 is provided on the nozzle body 21 to form the venturi flow channel 53, and the cross-sectional area of the venturi portion 51 is enlarged. The molten solder 11b, which is guided by the rear jet guide plate 24 and flows down, is configured to join together by a suction action.
[0042]
The venturi portion 51 is provided with three adjustment plates 54, which are constituted by both venturi adjustment plates 54A and 54B constituting both side edges of the venturi portion 51 and a flow rate adjustment plate 54C for adjusting the merging ratio. These adjustment plates 54A, 54B, 54C are all rotatable about the hinge 55, and after adjustment by rotation, the adjustment plates 54A, 54B, 54C can be locked and fixed. Each is provided with a locking and fixing means (not shown) using screws.
[0043]
The venturi forming plate 52 is provided with a jet wave flow rate adjusting plate 61 capable of sliding movement adjustment in the left-right direction of FIG. 4, and by adjusting the position in the left-right direction, the nozzle 22 has a blowing port 22. The flow rate of the molten solder 11 supplied and the flow rate of the molten solder 11 supplied to the venturi flow channel 53 can be adjusted. The jet wave flow rate adjusting plate 61 is provided with a long hole 62 in the adjusting direction, and is configured to be fixed at a required position by a screw 63 passed through the long hole 62.
[0044]
A guide plate 65 that can be adjusted in the vertical direction by a long hole 62 and a screw 63 is provided at the portion where the rear jet of the jet wave 12 flows down, and corresponds to the transport elevation angle θ ₁₁ of the transport conveyor 5. The height can be adjusted. That is, the inclination angle of the jet wave 12 can be adjusted by adjusting the height.
[0045]
A front jet guide plate 23 that can be adjusted up and down is provided in the same manner as described above at the portion of the jet wave 12 where the front jet flows down. The front jet guide plate 23 is provided on the wave width adjusting plate 64, and the wave width adjusting plate 64 is provided on the nozzle body 21 so that the position of the nozzle body 21 can be adjusted in the left-right direction in the figure. These position adjustments are constituted by the long holes 62 and the screws 63 as described above.
[0046]
That is, by positioning the wave width adjusting plate 64 in the left-right direction in the figure, it is possible to adjust the width of the air outlet 22, thereby adjusting the width of the jet wave 12.
[0047]
Further, by adjusting the relative height of the front jet guide plate 23 and the rear jet guide plate 24, the flow rate ratio between the front jet and the rear jet can be adjusted, and the jet wave 12 as described above. adjust the angle of inclination, it is possible to form a jet flow 12 corresponding to the conveyor elevation theta ₁₁ of conveyor 5.
[0048]
Of these embodiments, the important adjusting mechanisms according to the gist of the present invention are both the venturi adjusting plates 54A and 54B and the flow rate adjusting plate 54C. Both the venturi adjusting plates 54A and 54B adjust the degree of enlargement of the cross-sectional area of the venturi section 51, and the flow velocity adjusting plate 54C can adjust the forced discharge flow rate of the molten solder 11 flowing away from the peelback point 13. . That is, the amount of action of the venturi portion 51 and the forced discharge flow rate can be adjusted, and by these adjustments, the separation speed V ₁ of the molten solder 11 that is separated from the peelback point 13 can be adjusted. It is comprised as follows.
[0049]
In FIGS. 1 and 4, even if the rear jet guide plate 24 is not provided, the rear jet of the molten solder 11 can obtain the venturi effect due to the suction action of the venturi flow path.
[0050]
[ Third embodiment]
FIG. 5 is a side sectional view of a main part showing a third embodiment of the present invention, showing a jet nozzle portion of a soldering apparatus, and the same reference numerals as those in FIG. 4 indicate the same or corresponding parts. Further, similarly to the second embodiment of FIG. 4, the nozzle portion which is the gist of the invention and its vicinity are shown.
[0051]
The third embodiment soldering apparatus is obtained by configured to provide by adding a tray portion 71 to the soldering apparatus of the second embodiment. As shown in FIG. 5, a weir plate 72 capable of adjusting the vertical position is provided between the air outlet 22 and the tray part 71, and the vertical position is adjusted by a long hole 62 and a screw 63 at the overflow end 71 a of the tray part 71. A possible rear jet guide plate 24 is provided. A forced discharge channel 74 for forcibly discharging the molten solder 11 that is separated from the peel-back point 13 formed on the barrier plate 72 is formed. It is formed between the discharge flow path forming plate 73.
[0052]
By adjusting the relative height of the weir plate 72 and the rear jet guide plate 24 of the overflow end 71 a of the tray portion 71, it is possible to mainly adjust the separation angle θ ₁ of the molten solder 11 at the peel back point 13. by adjusting the flow rate of the molten solder 11 through the forced discharge passage 74, it is possible primarily to adjust the spacing speed V ₂ of the molten solder 11 in the peel-back point 13.
[0053]
In this case, the molten solder 11 flowing in the surface layer of the jet flowing from the peel back point 13 to the tray portion 71 gently flows down with a smooth surface shape due to the buffering action of the tray portion 71, but the forced discharge flow path 74 in the core portion. The flow rate of the molten solder 11 at the peelback point 13 is increased at a speed exceeding the free fall (free flow).
[0054]
Accordingly, it is possible to stably maintain the degree by the action of the tray portion 71 while simultaneously increasing the amount of solder attached to the fillet 14 shown in FIG. 6 and eliminating the solder bridge.
[0055]
【The invention's effect】
As described above, according to the soldering apparatus of the present invention, the configuration using the venturi flow path having the suction action so that the molten solder flowing through the peelback point can be forcibly discharged can be achieved by free fall. It becomes possible to generate a greater fillet forming force beyond the limit of the acting force. Therefore, it is possible to perform soldering without causing a solder bridge while increasing the amount of solder attached to form the fillet more than before. As a result, it is possible to perform high-quality soldering that does not cause soldering defects such as solder bridges, while improving the reliability of the soldered portion.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an essential part showing a first embodiment of the present invention.
FIG. 2 is a side sectional view of an essential part showing a reference example.
FIG. 3 is a side sectional view of an essential part showing a reference example.
FIG. 4 is a side sectional view of an essential part showing a second embodiment of the present invention.
FIG. 5 is a side sectional view of an essential part showing a third embodiment of the present invention.
6A and 6B are diagrams illustrating the formation of a fillet when performing flow soldering, in which FIG. 6A illustrates a formation factor, and FIGS. 6B and 6C illustrate an example of forming a fillet. It is a sectional side view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Land 3 Electronic component 4 Lead wire 11 Molten solder 12 Jet flow wave 13 Peel back point 14 Fillet 21 Nozzle body 22 Blow-off port 23 Front jet guide plate 24 Rear jet guide plate 25 Pump 26 Suction port 31 Venturi part 32 Venturi formation plate 33 Venturi flow channel 41 Forced discharge dedicated pump 42 Discharge flow channel 43 Discharge recirculation channel 44 Valve element 45 Hinge 51 Venturi section 52 Venturi formation plate 53 Venturi flow plate 54 Venturi adjustment plate 55 Hinge 61 Jet wave flow rate adjustment plate 64 Wave width Adjustment plate 65 Guide plate 71 Tray part 72 Dam plate 73 Discharge channel forming plate 74 Forced discharge channel

Claims (1)

In a soldering apparatus for supplying molten solder to a nozzle by a molten solder supply means to form a jet wave of the molten solder at the blowing port, and bringing the jet wave into contact with a wiring board to be soldered to perform soldering,
Providing a venturi flow path having a suction action as a forced discharge means for forcibly discharging the molten solder ejected from the blow hole in the vicinity of the blow hole ,
Soldering device characterized by

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