JP2010184251A - Apparatus for forming planar jet wave of soldering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for forming planar jet wave of soldering which hardly generates solder oxide and solder balls even when the opening area of a jetting unit is brought close to the opening area of a solder bath and consequently materializes high quality soldering by suppressing initial cost and running cost. <P>SOLUTION: The apparatus includes the solder bath 1 and a box-shaped jetting unit 3 having in the upper part an opening through which fused solder 2 in the solder bath 1 is jetted as a planar jet wave and made to flow back into the solder bath 1. In the jetting unit 3, there are installed rod-like members 8 as volume adjusting members, between the fused solder level formed in the jetting unit 3 with a pump 4 stopped and the opening end face formed by the opening 3a. The rod-like members 8, by obtaining volume so as to reduce a space capacity in the jetting unit 3, maintain within a prescribed limit the decrement of the fused solder level in the solder bath 1, which is produced when the fused solder 2 is jetted from the opening 3a by operating the pump 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a soldering method in which a molten solder is used as a plane-shaped jet wave, and the soldered work is brought into contact with a soldered part of a printed wiring board on which an electronic component is mounted at the same time. The present invention relates to a plane jet wave forming apparatus.

  As a method of performing soldering by supplying molten solder to a soldered part of a printed wiring board, a molten solder is jetted from a blower to form a jet wave, and the jet wave and the soldered part of the printed wiring board Is used.

  There are various shapes of jet waves, and the soldering method varies depending on the shape. For example, a mountain-shaped jet wave, a planar jet wave, a jet wave having a number of protrusions, a jet wave having a number of steps, and the like are known. Here, the plane-shaped jet wave generally refers to a jet wave that forms the plane shape horizontally.

  4 and 5 are diagrams for explaining a configuration example of a conventional soldering plane jet wave forming device, FIG. 4 is a view showing a longitudinal section, and FIG. 5 is a plan view seen from above. In FIG. 5, the motor is not shown for easy understanding.

  The solder tank 1 contains solder 2 that is heated by a heater (not shown) and is in a molten state. The temperature of the molten solder 2 is maintained at a predetermined temperature determined in advance by a temperature sensor and a temperature control device (not shown). That is, the heater control power is controlled by the temperature control device.

  Further, a box-shaped blower body 3 having a blower opening 3 a at the top is installed in the solder tank 1. Near the bottom of the blower body 3, a pump housing chamber 3b is formed so as to protrude outward, and a pump 4 for feeding the molten solder 2 is housed. The pump 4 is driven to rotate by a motor 6 coupled by a coupler 5, and as shown by an arrow F in FIG. 4, the molten solder 2 is sucked from a suction port 3c formed on the bottom surface of the pump housing chamber 3b and blown. Discharge into the mouth 3.

  The blower body 3 has a blower port 3a above the molten solder liquid surface formed in the solder tank 1 in a state where the pump 4 is stopped, and the pump 4 is operated to melt the molten solder from the solder tank 1. Is supplied, the molten solder is jetted as a plane-shaped jet wave from the blower port 3a and refluxed into the solder bath 1. That is, the blower body 3 is for forming a horizontal and planar jet wave (referred to as a plane jet wave), and the blower end surface formed by the blower port 3a is also normally configured horizontally. .

  Further, the opening area (blow hole area) of the air outlet 3a is configured to be larger than the plate surface shape of the printed wiring board W that is a work to be soldered, and is conveyed as indicated by the dotted arrow in the figure. The part to be soldered, that is, the lower surface of the plate W can come into contact with the molten solder 2 simultaneously. Thereby, the heat supply per unit time to the printed wiring board W can be maximized. In addition, in the blower body 3, for example, a porous plate 7 is provided as a rectifying means, and consideration is given so that the shape of the plane jet wave is stabilized.

  This type of soldering plane jet wave forming apparatus is disclosed as “(f) Flow dip type” on pages 48 to 49 of Non-Patent Document 1.

  In such a soldering plane jet wave forming apparatus, the larger the printed wiring board W, the larger the air outlet 3a is required, and the larger the capacity of the solder tank 1 is necessary.

  However, when the volume of the solder bath 1 is increased, the amount of solder put into the solder bath 1 is increased, and the initial cost is increased. In addition, since the melting and solidification (starting and stopping of the apparatus) of the solder 2 in the solder bath 1 is normally repeated at the start and end of production, when the amount of solder increases, the solder 2 is melted to a target temperature. A large amount of energy is required until the temperature is raised to a high temperature, which increases the running cost.

  Therefore, as shown in FIGS. 4 and 5, as much as possible around the air outlet 3 a of the air outlet 3 is not formed, that is, the distance between the outer surface of the air outlet 3 and the inner surface of the solder layer 1 is as much as possible. The size of the solder bath 1 is made as small as possible.

Electronic Technology Special Issue June 1981 Vol. 23 No. 7

  In FIG. 4, the liquid level position h <b> 1 of the molten solder 2 in the solder tank 1 indicated by a solid line indicates a position where the pump 4 is stopped. On the other hand, the liquid surface position h2 of the molten solder 2 in the solder tank 1 indicated by a dotted line indicates a position where the pump 4 is operating. That is, when the melted solder 2 is fed to the blowing port 3a of the blowing body 3 by operating the pump 4, the liquid level position of the molten solder 2 in the solder tank 1 is greatly increased by Δh (= h1-h2). Descend.

  In the state where the pump 4 is stopped, if the drop between the blower end surface of the blower body 3 and the molten solder liquid level h1 is h3, when the pump 4 is operated to form a plane jet wave, this drop, that is, the plane The reflux drop of the molten solder 2 forming the jet wave rapidly expands to (h3 + Δh + Δhf). Here, Δhf is the height from the blower end face to the surface of the plane jet wave.

  The descending amount Δh of the molten solder liquid level in the solder bath 1 due to the formation of the plane jet wave increases the ratio of the blow-out area S2 of the blow-out body 3 to the opening area S1 of the solder bath 1, and 1 / 2 or larger than 0.5, it increases rapidly.

The drop between the blower end surface of the blower body 3 and the molten solder liquid surface is h3, and the blower body 3 has a blower area of S2, so that the pump 4 is operated to start from the blower 3a of the blower body 3. When the molten solder 2 is jetted, the volume Qf of the molten solder 2 that is newly fed and filled into the blower body 3 is approximately:
Qf = (h3 + Δhf) · S2
It becomes.

Therefore, the descending amount Δh of the molten solder liquid level in the solder bath 1 is
Δh = Qf / (S1-S2)
= (H3 + Δhf) · S2 / (S1-S2)
= (H3 + Δhf) · k / (1-k)
It becomes. However, k = S2 / S1. Therefore, Δh increases rapidly when k is greater than 0.5.

  That is, when the blower area 3 of the blower body 3 is brought close to the opening area S1 of the solder tank 1 in order to reduce the initial cost and running cost, the descending amount Δh of the molten solder liquid level in the solder tank 1 increases rapidly. Become bigger. This is because the amount of molten solder newly fed and filled in the blower body 3 must be supplied from the periphery of the blower body 3.

  Then, the rapid expansion of the reflux drop (h3 + Δh + Δhf) when the molten solder 2 recirculates into the solder bath 1 when the plane jet wave is formed accelerates the oxidation rate of the molten solder 2. In addition, a large amount of solder balls are generated and scattered, causing problems such as adhesion of the solder balls to the printed wiring board W and contamination of the periphery.

  FIG. 6 is a diagram for explaining the acceleration of the molten solder 2 oxidation rate and the generation of a large amount of solder balls. The molten solder 2 overflowing from the blowing port 3a by forming a plane jet wave flows back into the solder bath 1 and falls. It is a figure which expands and shows a part. The rapid expansion of the reflux drop (h3 + Δh + Δhf) rapidly increases the reflux rate of the molten solder 2 having formed a plane jet wave into the solder tank 1, and thus the drop velocity Vd. As a result, a large amount of ambient atmosphere (atmosphere) is entrained in the molten solder 2, and the oxidation rate of the molten solder 2 is accelerated to generate a large amount of fine solder oxides, which are collected to form a molten solder liquid surface. A dross is formed in the body, and its mass generation occurs.

  The large amount of solder oxide increases the wasteful consumption of the solder 2, and the solder oxide is contaminated by contamination in the molten solder 2 and thus in the jet wave. It adheres to the plate W and deteriorates the electrical characteristics of the circuit, or severely shorts the circuit.

  Further, the increase in the falling speed Vd of the molten solder 2 increases the scattering at the time of reflux dropping onto the molten solder liquid surface in the solder tank 1, and a large amount of solder balls are scattered. When this solder ball adheres to the printed wiring board W being transported for soldering, the circuit is short-circuited or detached and dropped in the apparatus in which the printed wiring board W is incorporated, and enters the mechatronics mechanism section. There is a risk of causing the malfunction.

  The present invention has been made in view of the situation as described above, and even when the opening area of the blowing port of the blowing body is made close to the opening area of the solder bath, solder oxide and solder balls are hardly generated. It is possible to realize soldering with high soldering quality while suppressing initial cost and running cost.

The soldering plane jet wave forming apparatus according to the present invention includes a solder tank that accommodates solder that is heated and in a molten state, a blowing body that is installed in the solder tank, and the molten solder in the solder tank. A pump that feeds into the mouth, and the blow body has a blower above the surface of the molten solder formed in the solder bath when the pump is stopped. When the molten solder is fed from the solder bath by operating the molten solder, the molten solder is jetted as a plane jet wave from the blower opening and recirculated into the solder bath. The soldering plane jet wave forming device having an area larger than the plate surface shape of the plate-like workpiece to be soldered and larger than ½ of the opening area of the solder tank, The pump stops In this state, a volume adjusting member is provided between the molten solder liquid level formed in the blower body and the blower end surface formed by the blower, and the pump is operated to jet molten solder from the blower The descending part of the molten solder liquid level in the solder bath generated when the soldering is performed is maintained within a predetermined limit.
The present invention configured as described above includes a space portion in the blower body, specifically, a molten solder liquid level formed in the blower body when the pump is stopped, and a blower end surface formed by the blower. By providing a volume adjusting member between the two, a feature is that when the molten solder is fed to the blower body, the amount of molten solder newly filled in the blower body is reduced.

Another feature of the soldering plane jet wave forming apparatus according to the present invention is that the volume adjusting member is a partial aperture ratio adjusting member that adjusts a thickness distribution of a horizontal flow in a surface layer of the plane shaped jet wave. Also works. In addition, the partial opening ratio said here means the ratio of the opening area which occupies per unit area in a certain area | region, for example, the center part and edge part of a blower outlet.
By making the volume adjusting member function as a partial aperture ratio adjusting member in this way, for example, a flat horizontal jet wave with a thick horizontal flow is formed at a target portion, or the central portion of the flat jet wave is thin and the end is thick. A plane jet wave can be formed. In other words, the thick and thin portions of the horizontal flow of the plane jet wave can be selectively formed, and the optimum jet wave can be formed according to the mounting state of the work to be soldered. Become.

  According to the present invention, by providing the volume adjusting member, it is possible to reduce the descending amount of the molten solder liquid level in the solder bath and to reduce the reflux drop when the molten solder flows back into the solder bath. Therefore, even when the opening area of the blowing body is close to the opening area of the solder bath, solder oxide and solder balls are less likely to be generated, and the initial cost and running cost are reduced, and solder with high soldering quality is achieved. This is to make the attachment possible.

It is a figure showing the longitudinal section of the soldering plane jet wave forming device concerning the embodiment of the present invention. It is the top view seen from the upper part of the soldering plane jet wave forming device concerning the embodiment of the present invention. It is a figure explaining the thickness distribution of the horizontal flow of a plane jet wave, (a) is a figure explaining the example which arranged the rod-shaped member with a circular cross section at equal intervals, (b) is an ellipse with a vertical cross section It is a figure explaining the example which arranged the rod-shaped member of this by making it dense and dense at intervals. It is a figure which shows the longitudinal cross-section of the conventional soldering plane jet wave formation apparatus. It is the top view seen from the upper part of the conventional soldering plane jet wave formation apparatus. It is a figure explaining acceleration of the oxidation rate of molten solder and generation of a large amount of solder balls.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
(First embodiment)
(1) Configuration FIGS. 1 and 2 are diagrams illustrating a configuration of a soldering plane jet wave forming device according to an embodiment to which the present invention is applied. FIG. 1 is a diagram showing a longitudinal section passing through a rotation axis of a pump 4. FIG. 2 is a plan view seen from above. 3 is a diagram for explaining the horizontal flow thickness distribution of a plane jet wave, (a) is a diagram for explaining an example in which rod-like members 8 having a circular cross section are arranged at equal intervals, and (b) is a transverse diagram. It is a figure explaining the example which arranged the bar-shaped member 8 of the ellipse whose surface is vertically long with the space | intervals being dense. In addition, the same code | symbol is attached | subjected to the structure similar to the conventional soldering plane jet wave formation apparatus demonstrated in FIG. 4, 5, and the detailed description is abbreviate | omitted.

  In the blower body 3, the liquid level of the molten solder 2 in the solder bath 1 when the pump 4 is stopped, that is, the liquid level of the molten solder 2 formed in the blower body 3, and the blower A plurality of rod-shaped members (columnar members) 8 are provided side by side as a volume adjusting member between the blower end face formed by 3a.

  The rod-shaped member 8 increases the volume so that the space volume in the blower body 3 is reduced, thereby operating the pump 4 to cause the molten solder 2 to be jetted from the blower 3a. It functions as a volume adjusting member that maintains the descending portion of the molten solder liquid level within a predetermined limit.

  Further, the rod-shaped member 8 can be used as a partial aperture ratio adjusting member that adjusts the thickness distribution of the horizontal flow in the surface layer of the plane jet wave, in other words, can freely adjust the thick and thin portions of the horizontal flow of the plane jet wave. Function.

  In the example of FIGS. 1 and 2, the rod-shaped members 8 having a circular cross section are arranged at equal intervals as shown in FIG. 3A. However, as shown in FIG. The rod-shaped members 8 having a shape may be arranged with a close interval. In FIG.3 (b), the space | interval of the rod-shaped member 8 is wide at the center part of the blower opening 3a, and is made narrow at the horizontal direction edge part side.

  In the present embodiment, the frame body 9 is replaceably mounted in the air outlet 3 a of the air outlet body 3, and a plurality of rod-like members 8 are installed between the opposing surfaces of the frame body 9. For example, as shown in FIGS. 3A and 3B, a projection 3d is provided on the inner surface of the blower body 3, and the frame 9 is placed on the projection 3d. Good.

(2) Operation In FIG. 1, the liquid level position h <b> 1 of the molten solder 2 in the solder bath 1 indicated by a dotted line indicates a position where the pump 4 is stopped. On the other hand, the liquid surface position h2a of the molten solder 2 in the solder tank 1 indicated by the solid line indicates the position where the pump 4 is operating. That is, when the molten solder 2 is fed to the blowing port 3a of the blowing body 3 by operating the pump 4, the liquid level position of the molten solder 2 in the solder tank 1 is lowered by Δha (= h1-h2a). .

  At this time, the descending amount Δha of the molten solder liquid level in the solder bath 1 is significantly smaller by the volume of the rod-shaped member 8 than the descending amount Δh shown in FIG. As a result, when a plane jet wave is formed, the reflux drop of the molten solder 2 into the solder bath 1 is reduced to (h3 + Δha + Δhf). Here, Δhf is the height from the blower end face to the surface of the plane jet wave.

  That is, when the total volume of the rod-shaped member 8 is Qv, when the molten solder 2 is jetted from the blowing port 3a of the blowing body 3 by operating the pump 4, the blowing body 3 is newly fed and filled. The volume of the molten solder 2 is reduced to Qf−Qv.

Therefore, the descending amount Δha of the molten solder liquid level in the solder bath 1 is
Δha = (Qf−Qv) / (S1−S2)
= {(H3 + Δhf) · S2-Qv} / (S1-S2)
Thus, it can be reduced by Qv / (S1-S2).

  The closer the space volume (h3 · S2) of the blower body 3 near the blower port 3a and the total volume Qv of the rod-like member 8 are, the closer it is, the smaller the drop Δha of the molten solder liquid level can be made. . In other words, by adjusting the total volume Qv of the rod-like member 8, the amount of decrease Δha of the molten solder liquid level can be set to a desired value (within a predetermined limit).

  In order not to rapidly increase the amount of solder oxide generated and to prevent a large amount of solder balls from scattering, it is necessary to set the reflux drop (h3 + Δha + Δhf) to 40 mm or less, preferably 30 mm or less. . If this reflux drop is exceeded, a large amount of solder balls will suddenly scatter, and a large amount of air (atmosphere) will be engulfed in the molten solder 2 in the solder bath 1 to generate a large amount of solder oxide. become.

  Moreover, when the rod-shaped members 8 are arranged at equal intervals as shown in FIG. 3A, per unit area and per unit time of the molten solder 2 fed to the blowing port 3a of the blowing body 3. Can be distributed substantially uniformly. Therefore, the horizontal flow (arrow f) generated in the surface layer portion of the plane jet wave is thin at the center, as shown by the solid line and the dotted line in the figure, and the horizontal end of the blowing port 3a where the molten solder 2 overflows. It gets thicker as it gets closer.

  On the other hand, as shown in FIG. 3B, when the interval between the rod-like members 8 is wide at the center portion and narrow at the horizontal direction end portion side of the blower port 3a, the rod member 8 is fed to the blower port 3a of the blower body 3. The flow rate per unit area and unit time of the molten solder 2 is large at the center portion and is small at the horizontal direction end portion side of the blowing port 3a where the molten solder 2 overflows. Therefore, the horizontal flow (arrow f) generated in the surface layer portion of the plane jet wave is slightly thin at the center as shown by the solid line and the dotted line in the figure, but can be made substantially the same thickness.

  The thickness of the molten solder 2 flowing in the horizontal direction in the surface layer portion of the plane jet wave defines the rate of heat supply to the soldered portion such as the lead terminal of the electronic component mounted on the printed wiring board W. Generally, the heat supply rate increases as the thickness increases, so that the thickness of the molten solder 2 flowing in the horizontal direction increases as the heat capacity of the soldered portion determined by the size of the electronic component increases. It is good to make it. That is, the bar-like member 8 may be provided so as to control the thickness of the molten solder 2 flowing in the horizontal direction in the surface layer portion of the plane jet wave in accordance with the mounting state of the printed wiring board W.

  Since the rod-shaped member 8 is provided on the frame body 9 that fits into the air outlet 3a of the air outlet body 3 and can be exchanged, a frame body 9 in which the rod-shaped members 8 are arranged as desired is prepared according to the purpose. By replacing it, the thickness distribution state of the horizontal flow of the plane jet wave that is optimal for the mounting state of the plate-like workpiece to be soldered, that is, the printed wiring board W can be obtained.

  The cross-sectional shape of the rod-shaped member 8 is preferably a streamlined shape in that it does not hinder the flow of the molten solder 2, but may be a polygon such as a hexagon or an octagon. Moreover, although the straight rod-shaped member 8 is provided in parallel along the frame of the frame body 9, it may be provided obliquely. Moreover, you may arrange | position the rod-shaped member bent in the circular arc shape suitably. Further, for example, the thickness and shape of the rod-shaped member may be made different between the central portion and the end portion of the air outlet 2.

  Furthermore, the volume adjusting member (partial aperture ratio adjusting member) is not only configured by arranging rod-shaped members side by side, but also, for example, a lattice-shaped (net-shaped) member or a block body in which a large number of channels that penetrate vertically are formed. It may be used.

  The point is that the shape and arrangement of the partial aperture ratio adjusting members provided in the immediate vicinity of the blower port 3a of the blower body 3 control the flow direction and thickness of the molten solder 2 in the surface layer of the plane jet wave, and the distribution state thereof. Therefore, it is possible to control the solderability of the printed wiring board W brought into contact with the plane jet wave.

  In the soldering plane jet wave forming apparatus of the present invention, when soldering a plate-shaped workpiece to be soldered having a large plate surface shape, there is little contamination with solder oxide and solder balls, and it matches the mounting state of the electronic component. And uniform soldering. Therefore, it can be used for a soldering apparatus for performing soldering mounting of a large printed wiring board such as a mother board.

DESCRIPTION OF SYMBOLS 1 Solder tank 2 Molten solder 3 Blowing hole body 3a Blowing hole 3b Pump accommodating chamber 3c Suction port 3d Projection part 4 Pump 5 Coupler 6 Motor 7 Perforated plate 8 Bar-shaped member 9 Frame body

Claims (5)

A solder bath for containing solder that is heated and in a molten state;
A blower body installed in the solder bath,
A pump for feeding molten solder in the solder bath into the blower body,
The blower body has a blower port above a molten solder liquid surface formed in the solder tank in a state where the pump is stopped, and when the pump is operated, molten solder is discharged from the solder tank. When fed, the molten solder is jetted as a plane-shaped jet wave from the blowing port, and is recirculated into the solder bath,
A soldering plane jet wave forming device in which the opening area of the blower opening is larger than the plate surface shape of the plate-like workpiece to be soldered and is larger than 1/2 of the opening area of the solder bath,
In the blower body, a volume adjusting member is provided between a molten solder liquid surface formed in the blower body while the pump is stopped, and a blower end surface formed by the blower,
A soldering plane jet characterized by maintaining a descending amount of the molten solder liquid level in the solder bath generated when the molten solder is jetted from the blowing port by operating the pump within a predetermined limit. Wave forming device.   The soldering plane jet wave forming apparatus according to claim 1, wherein the volume adjusting member also functions as a partial aperture ratio adjusting member that adjusts a thickness distribution of a horizontal flow in a surface layer of the plane-shaped jet wave. .   The soldering plane jet wave forming apparatus according to claim 1, wherein the volume adjusting member is configured by arranging a plurality of rod-shaped members.   3. The soldering plane jet wave forming apparatus according to claim 2, wherein the volume adjusting member is configured by arranging a plurality of rod-shaped members, and the intervals between the plurality of rod-shaped members are made dense.   The soldering plane jet wave forming device according to claim 1, wherein the volume adjusting member is replaceably mounted in the blower body.

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