JP2004356161A - Automatic soldering equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide automatic soldering equipment that can completely eliminate the occurrence of incomplete soldering, bridges, and icicles and can make sufficient wetting into through holes. <P>SOLUTION: In this automatic soldering equipment, many cylindrical jetting ports are provided on a primary jetting nozzle and, at the same time, a secondary jetting nozzle is provided by bringing the advancing-side foamer of the secondary jetting nozzle nearer to the jetting ports arranged side by side on the leaving side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Technical Field]
The present invention relates to an automatic soldering apparatus for performing soldering of a printed circuit board.
[0002]
[Prior art]
As a method for soldering the printed circuit board, there is an immersion method in which the printed circuit board is brought into contact with molten solder and soldered, and this immersion method is performed by an automatic soldering apparatus. The automatic soldering device is a device in which processing devices such as a fluxer, a pre-heater, a jet solder bath, and a cooler are installed below a transport device that transports a printed circuit board. When soldering a printed circuit board with this automatic soldering device, while conveying the printed circuit board with a transport device, apply flux with a fluxer, preheat with a preheater, adhere solder in a jet solder bath, and cool with a cooler. As a result, soldering is performed.
[0003]
In a jet solder bath for attaching solder to a printed circuit board, a primary jet nozzle for jetting rough waves and a secondary jet nozzle for jetting gentle waves are installed. The rough waves jetted from the primary jet nozzle have the action of causing the molten solder to infiltrate well into the through holes of the printed circuit board or the corners that are square like chip parts, thereby eliminating unsolder. However, if the jet wave is rough, the state of solder attachment to the soldering part will not be stable, and the solder will adhere to the bridge between the adjacent conductors and the lead tip of the electronic component. A wiggle will be generated. The bridge on the printed circuit board hinders the normal functioning of the electronic device in which the printed circuit board is incorporated, and the tsura causes a discharge phenomenon from the tip of the tsura during use of the electronic device and causes the electronic device to fail. Further, if the solder does not sufficiently wet into the through hole, the adhesive strength between the lead of the discrete component and the printed circuit board is weakened. Therefore, the soldered portion of the printed circuit board should be free from bridges and wiggles, and the solder must be sufficiently wet into the through holes.
[0004]
It is the gentle wave that jets from the secondary jet nozzle that corrects these bridges and tsura. The gentle wave from the secondary jet nozzle melts the bridge and tsura and corrects it to the normal soldered part. Therefore, in the conventional automatic soldering apparatus, a primary jet nozzle that jets a rough wave and a secondary jet nozzle that jets a gentle wave are installed in a jet solder bath.
[0005]
Generally, in the conventional automatic soldering apparatus, the primary jet nozzle and the secondary jet nozzle are installed apart from each other. The reason for this is that if the primary jet nozzle and the secondary jet nozzle are too close together, the molten solder jetted out of each jet nozzle will flow into the molten solder jetted from the other jet nozzle. . As a result, the shape of the jet wave from the jet nozzle into which the molten solder has flowed is lost, and the action at each jet nozzle, that is, the unsoldering action at the primary jet nozzle and the bridge and tsura correction actions at the secondary jet nozzle, It will disappear. Therefore, in the conventional automatic soldering apparatus, the primary jet nozzle and the secondary jet nozzle are installed apart from each other.
[0006]
Even when the primary jet nozzle and the secondary jet nozzle are separated from each other, there was no problem when soldering using conventional Sn-Pb solder. This is because Sn-Pb solder has a low melting point of 183 ° C., and after soldering the printed circuit board with the primary jet nozzle, it takes some time to reach the secondary jet nozzle and the temperature drops slightly. This is because the solder and adhering at the primary jet nozzle do not solidify, and the molten bridge and tsura are completely corrected. Even if the bridge or tsura is solidified, the solidified bridge or tsura is at a temperature slightly lower than the melting point, so it can be easily melted when it is brought into contact with the molten solder with the secondary jet nozzle, and the bridge and tsura can be corrected. . In addition, when discrete components are soldered using Sn—Pb solder, the solder on the component surface side is sufficiently wet.
[0007]
Recently, lead pollution has become a problem, and the use of Sn—Pb solder, which has been used since ancient times, has been regulated. The problem with Sn-Pb solder is that when a printed circuit board using this solder is disposed of in landfill and comes into contact with acid rain having a high acidity, the Pb component in the solder is dissolved and mixed into groundwater. In this way, if humans or livestock drinks groundwater containing Pb components for many years, the use of Pb-Sn solder will be regulated as Pb components may cause lead poisoning accumulated in the body. I came.
[0008]
Therefore, in the electronic equipment industry, so-called “lead-free solder” that does not contain Pb at all has come to be used. Lead-free solder contains Sn as a main component and appropriately contains Ag, Cu, Sb, In, Bi, Zn, Ni, Cr, Mo, Fe, Co, P, Ge, Ga and the like. . Currently, lead-free solders frequently used in the electronic industry are Sn-Ag, Sn-Cu, and Sn-Ag-Cu. Since these lead-free solders have a melting point of 220 ° C. or higher, the temperature of the molten solder in the jet solder bath in the dipping method is 245 to 260 ° C., which is about 40 ° C. higher than the temperature used for Pb—Sn solder. It has become.
[0009]
When lead-free solder having a high melting point is used in a conventional automatic soldering device, that is, an automatic soldering device in which the primary jet nozzle and the secondary jet nozzle are set apart from each other, there are many occurrences of bridges and icicles. Insufficient wetting into the through hole also occurred. This is because the lead-free solder has a high melting point, and after soldering with the primary jet nozzle, it takes a long time to reach the secondary jet nozzle a little away from the lead-free solder. The temperature of the solder drops below its melting point, and the molten solder attached to the printed circuit board by the primary jet nozzle completely solidifies. Naturally, since the bridge and tsura generated on the printed circuit board and the solder inside the through-hole are also solidified, when contacting the molten solder jetted from the next secondary jet nozzle, The solder in the through hole cannot be completely melted, and bridges and tsura remain, or the wetting and spreading into the through hole may not be sufficient.
[0010]
Therefore, many automatic soldering apparatuses have been proposed in which the primary jet nozzle and the secondary jet nozzle are integrated to reduce the time required for the printed circuit board to move from the primary jet nozzle to the secondary jet nozzle (see Patent Documents 1 and 2). 3).
[0011]
[Patent Document 1] JP-A-58-187259 [Patent Document 2] JP-A-63-281768 [Patent Document 3] Japanese Utility Model Laid-Open No. 64-20959
[Problems to be solved by the invention]
By the way, in the conventional automatic soldering bath in which the primary jet nozzle and the secondary jet nozzle are integrated, the molten solder jetted from the secondary jet nozzle and flowed downward interferes with the molten solder jetted from the primary jet nozzle. As a result, the shape of the wave is destroyed, and the action of the primary jet nozzle is not made. Therefore, the conventional automatic soldering device that integrates the primary jet nozzle and the secondary jet nozzle can not generate rough waves at the primary jet nozzle, so it can not only eliminate bridges and tsura, but also gets wet enough in the through hole. Sometimes it didn't go up. In particular, when lead-free solder is used, these problems are prominent. SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic soldering apparatus that can completely eliminate unsoldering, bridges, and wiggles even when lead-free solder is used, and that can sufficiently wet up through holes.
[0013]
[Means for Solving the Problems]
When the primary jet nozzle and the secondary jet nozzle are brought close to each other, the present inventors cause the molten solder flowing out from the secondary jet nozzle to interfere with the molten solder jetting from the primary jet nozzle, thereby destroying the jet shape. As a result of diligent research on avoiding the problem, if the primary jet nozzle raises the jet port that forms the rough wave, the molten solder flowing out from the secondary jet nozzle will flow below the higher rough wave. The present invention was completed by paying attention to the fact that the shape of the molten solder jetted from the primary jet nozzle is not destroyed.
[0014]
The present invention provides an automatic soldering apparatus in which a primary jet nozzle for jetting rough waves and a secondary jet nozzle for jetting gentle waves are installed in a solder bath, and an uneven wave is formed above the primary jet nozzle. A large number of cylindrical jet nozzles are attached, and the entrance side former of the secondary jet nozzle is close to the cylindrical jet port arranged in parallel on the exit side of the primary jet nozzle. The automatic soldering apparatus is characterized in that the molten solder flowing out from the side former is in a position where it can merge with the molten solder flowing out from the primary jet nozzle without substantially breaking the uneven wave formed by the primary jet nozzle.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The secondary jet nozzle of the jet solder tank used in the automatic soldering apparatus of the present invention is provided with an entrance-side former and a exit-side former. The former determines the flow speed and angle of the molten solder after jetting from the jet nozzle. The exit-side former installed in the secondary jet nozzle lengthens the gentle flow and corrects the bridges and tsura formed in the soldering part of the printed circuit board during this time. The angle is variable so that the contact time of the printed circuit board with the molten solder can be adjusted. In addition, the height of the entry side former of the secondary jet nozzle can be adjusted so that the molten solder that has flowed to the primary jet nozzle side does not break the rough waves of the irregularities formed by the primary jet nozzle.
[0016]
The present invention will be described below with reference to the drawings. 1 is a cross-sectional perspective view of a jet solder bath installed in the automatic soldering apparatus of the present invention, FIG. 2 is a plan view of a jet solder bath in a state where molten solder is not jetted, and FIG. 3 is a cross-sectional view taken along line XX of FIG. FIG. 4 is a diagram for explaining a state in which molten solder is jetted, FIG. 4 is a cross-sectional view of another embodiment of the present invention, and FIG. 5 is an enlarged view of a main part of FIG.
[0017]
The jet solder tank 1 is provided with a primary jet nozzle 2 and a secondary jet nozzle 3, and solder 4 is put inside. The solder 4 put into the solder bath 1 is heated and melted by a heater (not shown) so as to be maintained at a predetermined temperature. The primary jet nozzle 2 and the secondary jet nozzle 3 are closed on both sides by side walls 5 and 5 and connected to ducts (not shown). A jet pump (not shown) is also installed at the end of the duct, and the shaft 6 of the jet pump projects to the surface of the molten solder. A pulley 7 is attached to the end of the shaft 6 protruding above the liquid surface, and is linked to a pulley 9 of a motor 8 fixed outside the solder tank 1.
[0018]
The primary jet nozzle 2 is provided with a large number of cylindrical jet ports 10. The cylindrical jet port communicates with the primary jet nozzle 2 and is placed on the primary jet nozzle 2 at a staggered lattice position. A line connecting the outlets of the jet ports 10 and 10a of the primary jet nozzle 2 in the traveling direction of the printed circuit board is substantially horizontal.
[0019]
The secondary jet nozzle 3 has a wide outlet through which molten solder is jetted, and an entrance-side former 11 and an exit-side former 12 are attached to the upper part. The entrance-side former 11 has a short eave-like shape, and its tip is close to a cylindrical jet port 10a (hereinafter referred to as the exit-side jet port) arranged in parallel on the exit side of the primary jet nozzle 2. That is, the primary jet nozzle 2 and the secondary jet nozzle 3 are not in contact with each other, but are separated so that the molten solder flowing out from the secondary jet nozzle does not break the waves jetted from the primary jet nozzle, as will be described later. . Further, the entry-side former 11 can be adjusted in the vertical direction (arrow A in FIG. 3). The exit-side former 12 attached to the secondary jet nozzle 3 has an attachment portion to the secondary jet nozzle that is freely rotatable by a shaft 13 (arrow B in FIGS. 1 and 3), and the inclination angle is variable. ing.
[0020]
Here, the jet state of the molten solder in the jet solder tank installed in the automatic soldering apparatus of the present invention will be described.
[0021]
The motor 8 is operated and the molten solder 4 is sent into the duct by a jet pump (not shown), and the molten solder is jetted from the primary jet nozzle 2 and the secondary jet nozzle 3. At this time, as shown in FIG. 3, the primary jet nozzle 2 jets molten solder from each jet port 10... 10a. The molten solder that swells and jets at this time is in a state where the top of the jet is constantly swaying, and this becomes a rough wave of the primary jet.
[0022]
The wave jetted from the secondary jet nozzle is a gentle wave because the molten solder jets from the wide jet outlet, and this gentle wave flows along the entrance-side former 11 and the exit-side former 12. The molten solder flowing along the entry-side former 11 merges with the molten solder that has flowed out from the jet openings 10, 10 a, because the entry-side former 11 is close to the exit-side jet openings 10 a of the primary jet nozzle 2. To do. At this time, since the jet ports 10 and 10a of the primary jet nozzle 2 are cylindrical and the outlet from which the molten solder jets is at a high position, the molten solder flowing along the entry-side former 11 flows into the jet port 10 of the primary jet nozzle 2. ... it flows below the exit of 10a ..., and does not break all the rough waves that spout from the spout. However, since the outlet of the exit side jet port 10a is close to the entry side former 11, the molten solder flowing out from the entry side former slightly breaks the shape of the molten solder flowing out from the exit side jet port 10a. Even if the shape of the molten solder flowing out from the exit side jet port 10a is slightly collapsed, there is no problem because unsolder is eliminated at the other jet ports 10.
[0023]
In the primary jet nozzle shown in FIGS. 1 to 3, the line connecting the outlets of the jet ports 10 and 10a in the traveling direction of the printed circuit board (arrow C in FIG. 3) is substantially horizontal. Therefore, when the printed circuit board is transported at a transport angle of 3 to 5 degrees, the printed circuit board enters deeply with respect to the molten solder jetted from the jet port 10 (the leftmost in the figure) installed in the first row on the entry side. The molten solder that comes into contact and jets from the jet port 10a (the rightmost in the figure) installed in the last row on the exit side is in shallow contact.
[0024]
As described above, even when the printed board enters deeply into the molten solder jetted from the jet port on the entry side, the molten solder jetted from the jet nozzle does not cover the surface of the printed board due to its surface tension. However, ideally, it is more effective to eliminate unsoldering when the top of the molten solder jetted from each jet port contacts the printed circuit board in the same state.
[0025]
Therefore, an embodiment will be described in which the line connecting the outlets of the jet nozzles has substantially the same inclination as the conveyance direction of the printed circuit board.
[0026]
4 and 5 show another embodiment of the jet solder bath installed in the automatic soldering apparatus of the present invention. The jet solder bath shown in FIGS. 4 and 5 is different from the jet solder bath shown in FIGS. 1 to 3 in the angle of the line connecting the outlet of the jet port of the primary jet nozzle. The same parts as those in FIGS.
[0027]
A large number of cylindrical jet ports 10... 10 a... Are attached to the upper part of the primary jet nozzle 2. A line connecting outlets 10 ..., 10a ... of the secondary jet nozzle in the traveling direction of the printed circuit board (arrow C in FIG. 4) is inclined upward in the exit side direction. This inclination angle is substantially the same angle (β) as the conveyance angle (α) of the printed circuit board with respect to the horizontal.
[0028]
In this way, if the line connecting the outlets of the jet openings is inclined upward, the top part of the molten solder jetted from the respective jet openings becomes substantially the same as the transport angle of the printed boards, so all the printed boards are It comes to contact on the same conditions as the molten solder spouted from a jet port, and can also eliminate unsoldering. Moreover, in this jet solder tank, since the exit of the exit side jet port 10a is higher than the exit of the entrance side jet port 10, the molten solder jetted from the exit side jet port 10a is the exit side of the secondary jet nozzle 3. It is rarely affected by the molten solder flowing out of the former 11, and rough waves in the same state are formed from all the jets to eliminate unsolder.
[0029]
Further, in the primary jet nozzle whose exit side is inclined upward, since the entrance side of the upper surface of the primary jet nozzle 2 becomes an inclined surface, the molten solder flowing out from the jet port of the primary jet nozzle 2 vibrates along the inclined surface. And flow toward the entry side. When the molten solder flows vigorously on the upper surface of the primary jet nozzle in this way, the molten solder drawn from the flow and entering the former-side former of the secondary jet nozzle also flows vigorously along the upper surface of the primary jet nozzle. Therefore, it does not interfere with the jet of molten solder jetted from the exit side jet port, and a stable jet is produced from the jet nozzle.
[0030]
The printed circuit board is soldered by the automatic soldering apparatus of the present invention having the above-described structure as follows. While the printed circuit board is transported as shown by the one-dot chain line in FIG. 3 by a transport device (not shown), flux is applied by a fluxer (not shown) and preheated by a preheater to arrive at the jet solder tank 1. In the jet solder bath 1, the printed circuit board is in contact with the rough waves of irregularities spouted from a large number of cylindrical jet ports 10 ... 10a of the primary jet nozzle 2, and the corners and through-holes of chip parts that are difficult for solder to enter. It penetrates into the inside and soldering without unsoldering is performed. However, in soldering with rough waves, bridges and wiggles are generated in the soldered portion of the printed circuit board, and wetting into the through hole is not sufficient. Therefore, for these corrections, the printed circuit board is brought into contact with a gentle wave jetted from the secondary jet nozzle 3 installed close to the primary jet nozzle 2.
[0031]
In the automatic soldering apparatus of the present invention, the primary jet nozzle and the secondary jet nozzle are close to each other, and the molten solder flowing out from the entry-side former 11 of the secondary jet nozzle 3 is the jet port 10 of the primary jet nozzle 2. It merges with the molten solder that has flowed out of…. Therefore, the printed circuit board soldered by the rough wave of the primary jet nozzle 2 is brought into contact with the gentle wave jetted from the secondary jet nozzle immediately after soldering. That is, the automatic soldering apparatus of the present invention can perform soldering without time difference in which the molten solder attached to the printed circuit board by the primary jet nozzle can be brought into contact with the gentle wave of the secondary jet nozzle in the molten state. Therefore, even when lead-free solder having a high melting point is used, the solder adhering with the primary jet nozzle is brought into contact with the molten solder jetted with the next secondary jet nozzle in a molten state or at a high temperature close to the melting point. be able to.
[0032]
In the automatic soldering apparatus of the present invention, Sn-3Ag-0.5Cu lead-free solder (melting point: 217 ° C) is put into a jet solder bath, and the temperature of the molten solder is set to 250 ° C to perform soldering of the printed circuit board. As a result, there was no occurrence of bridges or icicles, and wetting into the through holes was good. On the other hand, when soldering was carried out under the same solder and the same conditions as described above with the automatic soldering apparatus of the conventional automatic soldering apparatus, that is, the automatic soldering apparatus in which the primary jet nozzle and the secondary jet nozzle were set apart, There were many icicles, and wetting into the through hole was not enough.
[0033]
【The invention's effect】
As described above, the automatic soldering apparatus of the present invention hardly breaks the rough waves jetted from the primary jet nozzle even though the primary jet nozzle and the secondary jet nozzle are installed close to each other. After the solder is attached by the primary jet nozzle, the solder can be brought into contact with the molten solder jetted from the next secondary jet nozzle while maintaining the molten state. Therefore, even when lead-free solder with a high melting point is used, the solder adhering with the primary jet nozzle can be brought into contact with the gentle wave of the secondary jet nozzle in a molten state or while maintaining a high temperature close to the melting point. Therefore, it is possible to completely fix the bridge and icicle and to perform soldering with excellent reliability that the wetting into the through hole is sufficient.
[Brief description of the drawings]
FIG. 1 is a perspective sectional view of a jet solder bath installed in an automatic soldering apparatus of the present invention. FIG. 2 is a plan view of a jet solder bath in a state where molten solder is not jetted. FIG. 4 is a cross-sectional view illustrating a state in which molten solder is jetted. FIG. 4 is a perspective cross-sectional view of another embodiment of a jet solder bath installed in the automatic soldering apparatus of the present invention. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Jet solder tank 2 Primary jet nozzle 3 Secondary jet nozzle 4 Molten solder 10 Jet port 11 Entrance side former 12 Exit side former

Claims (4)

In an automatic soldering device where a primary jet nozzle that jets rough waves and a secondary jet nozzle that jets gentle waves are installed in the solder bath, a number of cylindrical shapes that form uneven waves above the primary jet nozzle A jet port is attached, and the entrance side former of the secondary jet nozzle is close to the cylindrical jet port arranged side by side on the exit side of the primary jet nozzle, and the entrance side former flows out of the entrance side former. An automatic soldering apparatus in which the molten solder is in a position where it can join with molten solder flowing out of the primary jet nozzle without substantially breaking the uneven wave formed by the primary jet nozzle. 2. The automatic soldering apparatus according to claim 1, wherein the primary jet nozzle has a substantially horizontal line connecting the outlet of the cylindrical jet port in the traveling direction of the printed circuit board. 2. The automatic soldering apparatus according to claim 1, wherein the primary jet nozzle has a line connecting the outlet of the cylindrical jet port in the traveling direction of the printed circuit board and is inclined upward in the exit side direction. 2. The automatic soldering apparatus according to claim 1, wherein a height of the entry-side former of the secondary jet nozzle is adjustable.

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