JP5199974B2 - Soldering method for soldering apparatus and pallet apparatus used therefor - Google Patents

Description

  The present invention belongs to the technical field of soldering processing to a printed circuit board on which electronic components are mounted, and particularly relates to a soldering method for a soldering apparatus in which a soldering part is immersed in molten solder and a pallet apparatus used therefor.

  In an apparatus for soldering by immersing a printed circuit board on which electronic components are mounted in molten solder (flow type soldering apparatus), the printed circuit board is removed from the liquid surface of the molten solder (commonly called “soldering”). In addition, a technique is adopted in which the printed circuit board is detached while being inclined with respect to the liquid surface (hereinafter referred to as “tilted separation”). However, in this method and conventional device configuration, when lead-free solder is used, the melting temperature is high and the wettability is reduced, so that the solder defect (solder short, solder bridge, etc.) is lower than conventional lead-containing solder. ) Is likely to occur and has become a problem. In order to cope with this, various devices with various ideas have been disclosed (see, for example, Patent Documents 1 and 2).

  In addition, the printed circuit board is placed and held on the upper surface side of the pallet device in which the opening corresponding to the soldered part of the mounted electronic component is formed, transported together with the pallet device and immersed in the molten solder, An apparatus for performing soldering through an opening is disclosed (for example, see Patent Document 3). The mounting surface of the printed circuit board of this pallet device functions as a mask to prevent the solder from adhering to areas other than the soldering area of the printed circuit board, and damage to other electronic components due to the thermal history of lead-free solder with a high melting point Usually, it is generally used to avoid (copper erosion, lift-off, solder bridge, etc.).

JP 58-215092 (page 2-4, FIG. 1) JP 2004-228247 A (page 4-8, FIG. 3) JP 2007-109959 A (pages 3-6, FIG. 5)

  However, the method of holding the printed circuit board disclosed in the above-mentioned patent document on the pallet device and inclining it integrally with the pallet device so as to separate from the liquid surface of the molten solder has the following problems.

  That is, the conventional pallet apparatus has a larger thickness and planar dimensions than the printed circuit board in order to improve heat resistance, and the entire occupied volume is large. For this reason, the volume of drainage when immersed in molten solder becomes large, and a sudden drop in the liquid level occurs at the time of detachment from the solder liquid level, leading to solder failure.

  In order to minimize the occurrence of solder defects as much as possible, it is conceivable to reduce the pulling speed of the pallet device. However, with lead-free solder whose melting temperature is several tens of degrees higher than lead-containing solder, There was a problem that the frequency of solder defects such as solder shorts and solder bridges due to copper erosion due to fluctuations and poor wettability increased. In addition, a decrease in production efficiency due to a delay in cycle time (soldering processing time) has been a problem that cannot be ignored.

  In addition to the above problems, in the flow type soldering device in which molten solder is jetted from a nozzle arranged in the solder bath and immersed in the printed circuit board, a large amount of molten solder that has entered the opening of the pallet device is dragged along with the inclination separation. There was a risk that solder failure would occur frequently due to the phenomenon of sudden drop after rising.

  Therefore, in order to solve the above problems, the present invention is a soldering apparatus that moves a pallet device holding a printed board and performs soldering to the printed board. In addition to providing a solder cutting method with few defects, a pallet apparatus used in this method is provided.

  As means for solving the above problems, a solder cutting method in a soldering apparatus is provided as a first invention according to the present application. The configuration of the present invention is as follows.

First invention is a printed circuit board (hereinafter abbreviated as "substrate".) To the pallet assembly holds, in the solder cutting method of soldering apparatus for performing soldering to the substrate by the movement of the pallet assembly, the pallet After the apparatus is lowered and the printed circuit board is immersed in the solder liquid surface of the molten solder bath, the pallet apparatus is allowed to stand at the immersion position, and the printed circuit board Only the printed circuit board is separated from the liquid surface of the molten solder while gradually increasing the inclination angle with respect to the solder liquid surface .

  The separation of the substrate from the liquid surface of the molten solder (hereinafter abbreviated as “liquid surface”) is characterized by an inclined separation that raises one end of the substrate. More specifically, one end side of the substrate is moved to the upper side so that the substrate is gradually separated from the liquid surface from the one end side. In other words, the substrate that is in contact with the entire surface of the substantially horizontal liquid surface is brought into contact with the liquid surface from one end side of the substrate surface by lifting one end side of the substrate and moving it upward by lifting or pushing up. Is a method of gradually separating the. As a result, the original substrate is substantially horizontal because the entire bottom surface is in contact with the liquid surface, but the liquid is gradually moved by moving one end of the substrate so that the angle between the substrate bottom surface and the liquid surface gradually increases. It is a method of pulling away from the surface. The substrate in this process has a gradually increasing tilt angle.

Next, a pallet device for realizing the above-described solder cutting method is provided as a second invention according to the present application. The configuration of the present invention is as follows.
The second invention of the present application relates to a pallet apparatus in a soldering apparatus that moves a pallet apparatus holding a substrate and performs soldering to the substrate. Only the substrate held in the pallet apparatus is moved with respect to the solder liquid surface of the molten solder bath. It is characterized by having a tilting mechanism for tilting. The soldering apparatus includes a transport mechanism that moves the pallet device to a predetermined position above the solder tank, and a lifting mechanism that moves the pallet apparatus up and down toward the liquid level of the solder tank at a predetermined position in cooperation with the pallet apparatus. ing. In addition, about the structure of these conveyance mechanisms and raising / lowering mechanisms, since what is necessary is just to apply a well-known general mechanism, it abbreviate | omits about detailed description and publication of drawing.

  The tilt mechanism includes an engagement frame that engages with one end side of the substrate held by the pallet device, and vertical movement means that raises and lowers the engagement frame. Here, the engagement frame includes an engagement portion that engages with one end side of the substrate, and an arm that extends from the engagement portion to the side opposite to the engagement portion along both side edges of the substrate. The up-and-down moving means includes a lever on which a drive source arranged in the pallet device acts, and a linkage member that links the lever and the engagement frame.

  The engagement frame can be rotated with respect to the pallet device at the distal end portion on the side opposite to the engagement portion of the arm. For example, a pin, a bearing, or the like may be disposed and coupled. Accordingly, when the engagement frame is raised and lowered, the substrate engaged with the engagement frame is inclined with the coupling portion as the rotation axis, and the inclination operation is also smooth.

  The linkage member of the vertical movement means is constituted by the linkage of the lever and the engagement frame, and a guide means is provided between the two in order to facilitate the transmission of the driving force. For example, the guide means is preferably a groove, a guide plate, a slide guide, or the like. Thereby, the transmission of the driving force becomes smooth, and the operation and speed control by the driving source of the engagement frame becomes easy.

  The drive source for the vertical movement means is preferably a servo motor, a stepping motor, or the like that can control the rotational speed and rotational position. However, a pneumatic or hydraulic linear actuator that reciprocates two positions is used. It may be adopted. Further, transmission of the drive source is not limited to the lever, and transmission means such as a link mechanism, a gear, a rack and pinion, and a belt may be appropriately employed.

  The tilt mechanism of the present invention is configured to move the one end side of the substrate up and down via the engagement frame, but omits the engagement frame and, for example, a jig that directly engages the substrate with the vertical movement means May be arranged in advance, or an opening having a specific shape may be formed, and the vertical movement means may be engaged with these openings.

  The soldering method of the soldering apparatus according to the present invention has the following effects in order to adopt the above method.

  First, since the substrate is immersed in the molten solder in the solder tank while being held in the pallet apparatus, the pallet part of the pallet apparatus can enjoy the advantages of masking and heat resistance.

  Next, in the immersion position with the substrate held on the pallet device, the pallet device can be stopped, and only the substrate can be detached from the liquid surface (or inclinedly detached) while leaving the pallet device. For this reason, generation | occurrence | production of a solder defect is suppressed compared with the conventional method and apparatus which were made to incline-separate integrally with a pallet apparatus. This is because there is no sudden change in the liquid level when the substrate is separated from the molten solder integrally with the pallet apparatus having a large occupied volume.

  In addition, since there is no sudden liquid level fluctuation, the degree of freedom in controlling the substrate separation speed is increased, and the cycle time can be shortened while further reducing solder defects.

  This effect contributes to the improvement and stabilization of the soldering quality when using lead-free solder with reduced wettability, and the contribution to the reduction of the soldering cost of the board becomes significant.

It is a partially cutaway external perspective view showing a pallet device and a solder bath. It is an assembly perspective view of a pallet device. It is a perspective view which shows the vertical movement means of a pallet apparatus. It is an external appearance perspective view which shows the inclination state of the board | substrate in a pallet apparatus. It is operation | movement explanatory drawing which shows the solder cutting in a pallet apparatus. It is a perspective view which shows the example of a change of a pallet apparatus.

Hereinafter, embodiments of a soldering method for a soldering apparatus according to the present invention and a pallet apparatus used therefor will be described in detail with reference to the drawings.
In the following description, for the convenience of explanation, the invention of the pallet apparatus as the second invention will be explained first, and then the invention of the soldering method as the first invention will be explained.

  1 is a partially cutout perspective view showing a pallet device and a solder bath, FIG. 2 is an assembly perspective view of the pallet device, and FIG. 3 is a perspective view showing vertical movement means of the pallet device. FIG. 5 is an external perspective view showing an inclined state of the substrate in the pallet apparatus, and FIG. 5 is an operation explanatory view showing solder cutting in the pallet apparatus.

The pallet apparatus 1 according to the present embodiment includes a solder tank 8 that stores molten solder 82 and a transport mechanism (illustrated) that horizontally moves (arrow X) the pallet apparatus 1 that holds the substrate 7 above the solder tank 8. And an elevating mechanism (not shown) that moves up and down (arrow Y) toward the liquid level of the molten solder 82 jetted from the molten solder 82 or the jet nozzle 81 installed in the tank from the upper position of the solder bath 8. Movement control is performed.
In addition, since this mechanism itself uses a known general technique, detailed description and drawings are omitted in this specification.

  The solder tank 8 is a rectangular container opened upward, in which molten solder 82 is stored, and a nozzle opened upward with an opening shape larger than the horizontal projection area of the substrate 7 in the tank. 81 is arranged. In addition, as long as the lower part of the pallet apparatus 1 can be immersed, it is good also as a stationary solder tank which abbreviate | omitted the said nozzle 81. FIG.

  Next, the pallet apparatus 1 which is the main point of the invention will be described. The pallet device 1 includes a frame 2, a substrate holding unit 3, and an inclination mechanism 4 as main components. The pallet apparatus 1 holds the substrate 7 and immerses it in the molten solder 82 by transporting and raising / lowering the substrate 7 in cooperation with other mechanisms to perform soldering to the substrate 7.

  A frame 2 that serves as an overall support base of the pallet device 1 is formed by connecting a hard column material such as metal or resin or a square pipe in a rectangular frame shape, and the above-described transport mechanism and lifting mechanism are linked or attached.

  A thick plate-like suspension plate 21 is fixed to one opposing portion of the inside of the frame 2, and two suspension plates 21, 21 that are arranged opposite to each other are suspended downward. Suspension arms 22 and 22 are arranged at predetermined intervals, respectively.

  The substrate holding part 3 is supported by the suspension arm 22 and is formed by a mounting surface 32 for mounting and holding the substrate 7 and an outer frame 31 for retaining the outer periphery of the mounting surface 32. A flange 31 a is formed outside the outer frame 31 in the opposing direction of the suspension arms 22, 22. The lower end portion of the suspension arm 22 of the frame 2 is engaged with the flange 31a.

  The placement surface 32 is formed with a positioning groove 32a adapted to the outer shape of the substrate 7 to be held. The positioning groove 32a is to be fitted with the substrate 7 to ensure positioning and position reproducibility at the time of mounting. Three rectangular through holes 32b are formed inside the positioning groove 32a. The through-hole 32b has a wide cross-sectional shape so that the molten solder 82 can be easily guided to the soldered portion of the substrate 7.

  In addition, a strip-shaped escape groove 32 c that partially overlaps the positioning groove 32 a and whose longitudinal side is longer than the positioning groove 32 a is formed on the mounting surface 32 along the side on one side of the outer frame 31. The escape groove 32c is formed deeper than the positioning groove 32a and secures a space for accommodating an engagement portion 51 of the engagement frame 5 described later.

  Furthermore, a crank-shaped restraining plate 33 that is continuous from the upper surface of the outer frame 31 toward the mounting surface 32 is disposed at two locations of the escape groove 32 c and the outer frame 31 on the opposite side. The holding plate 33 partially protrudes from the upper surface of the end portion of the substrate 7 fitted in the positioning groove 32a to prevent the substrate 7 from being lifted or displaced from the positioning groove 32a.

  The through hole 32b is formed in conformity with the position of the lead 72 of the electronic component 71 of the substrate 7, that is, the soldered portion on the back surface side of the substrate 7. Therefore, the mounting surface 32 on which this is formed is appropriately replaced and changed according to the specifications of the substrate 7 to be soldered.

  The substrate 7 held on the mounting surface 32 is tilted while the one end side thereof is raised by the tilting mechanism 4 to increase the sandwich angle with respect to the mounting surface 32. The tilt mechanism 4 includes an engagement frame 5 and vertical movement means 6.

  First, the engagement frame 5 is disposed so as to be accommodated inside the outer frame 31 of the substrate holding unit 3. The engaging frame 5 forms two rotating arms 52, 52 parallel to one side from both ends thereof along the inner side of the outer frame, with the band-plate-like engaging portion 51 as a base. The appearance is substantially U-shaped in plan view. Further, the engaging portion 51 is a plate body that fits inside the escape groove 32c of the substrate holding portion 3 and fits in its entirety, and a part of the back surface on one side of the substrate 7 fitted in the positioning groove 32a. Is engaged. The escape groove 32c is formed in a band shape having only one side longer than the positioning groove 32a of the substrate 7, and the upper surface of the engagement portion 51 is formed to a depth that does not contact the back surface of the substrate when the engagement portion 51 is received. ing.

  Each rotating arm 52 is formed parallel to one side from both ends of the engaging portion 51, and the tip end side thereof is pivotally supported by a pin 53 disposed on the side surface of the outer frame 31 of the substrate holding portion 3. ing. Further, the separation distance between the rotating arms is set so as to exceed the dimension of the positioning groove 32 a, and the rotating arm 52 has a dimension longer than the dimension of one side of the substrate 7 and faces along both side edges of the substrate 7. Located to do.

  A hooking portion 54 is disposed on the engaging portion 51 of the engaging frame 5. The hook portion 54 is disposed at a position biased to one side of the engaging portion 51 and protrudes to the opposite side of the rotating arm 52. The hook portion 54 has a U-shape that is upwardly convex in a side view, and maintains a gap that does not interfere with the outer frame 31 of the substrate holding portion 3, while following the outer shape of the substrate holding portion 3. And a flange portion 54a extending horizontally outward is formed.

  The vertical movement means 6 is engaged with the hook portion 54. As shown in FIG. 3, the vertical movement means 6 includes a linkage member 61 that engages with the flange portion 54 a and a lever 62 that transmits an operating force of a motor 63 serving as a drive source to the linkage member 61. doing.

  The linkage member 61 includes a claw portion 61a, and a rail 61b and a guide 61d that guide the claw portion 61a upward. The claw portion 61a has a concave portion that engages with the flange portion 54a of the engagement frame 5 on the lower side, and the upper side is fixed to the rail 61b that is linearly guided upward by the guide 61d. The guide 61 d is fixed to the side surface portion of the suspension plate 21 of the frame 2.

  A roller 61c functioning as a cam follower is mounted in a horizontally projecting manner and rotatably on the opposite side of the rail 61b (on the drawing) to the substrate holding unit 3 at the upper end (rightward in FIG. 3). The lower surface on the circumferential side of the roller 61c follows the upper surface on the one end side of the lever 62.

  The lever 62 has a substantially rectangular shape and is pivotally supported via a bearing portion 62a fixed to the side surface portion of the suspension plate 21 of the frame 2 at the bent portion. Further, a cam follower 62b is attached to the opposite end that contacts the roller 61c. The cam follower 62b follows the lower surface of the cam 63a attached to the output shaft of the motor 63 serving as a drive source. A driving force is supplied from the motor 63 as a reciprocating rotational motion (oscillating motion) within a predetermined rotational angle range. As the type of the motor 63, a servo motor capable of controlling the rotation speed and the rotation angle is adopted, but a stepping motor only for angle control may be used.

  Next, the soldering method of the soldering apparatus performed using the pallet apparatus 1 having the above configuration will be described in detail.

  The substrate 7 is held by the pallet device 1 and is transported to a position above the solder bath 8 by a transport mechanism (not shown), and is horizontally lowered to the liquid level of the molten solder 82 in the solder bath 8 by a lift mechanism (not shown). The back surface is immersed in the molten solder 82. By this immersion, the molten solder 82 comes into contact with the part to be soldered of the substrate 7 exposed from the through hole 32b, and the lead 72 is soldered.

  After performing the soldering process, the vertical movement means 6 of the tilting mechanism 4 is operated while the pallet device 1 is left stationary, and the engagement frame 5 is pulled up via the hook portion 54. The operation of the vertical movement means 6 will be described in detail with reference to FIG. 3. First, the motor 63 is activated to rotate the cam 63a counterclockwise (arrow r) in the drawing. In conjunction with this, the cam follower 62b of the lever 62 is pushed down, and the linked lever 62 is operated to push up the roller 61c on the other end side upward. The rail 61b on which the roller 61c is disposed is smoothly moved upward (arrow a) while being guided by the guide 61d, and the claw portion 61a disposed on the lower end portion of the rail 61b is pulled upward.

  When the claw portion 61a is pulled up, as shown in FIGS. 4 and 5, the collar portion 54a of the hook portion 54 of the engagement frame 5 is engaged with this, and one end side of the engagement frame 5 is moved to the rotating arm 52. The pin 53 is pulled upward by a rotational motion with the pin 53 as a rotational axis. The pulling movement of the engagement frame 5 rises while tilting integrally with the substrate 7 partially engaged with the engagement frame 5. Along with this, the substrate 7 is detached from the liquid surface of the molten solder 82 (arrow p). At this time, the substrate 7 positioned on the pin side of the engagement frame 5 is not greatly displaced by the positioning groove 32a and the holding plate 33.

  By pulling up the engagement frame 5, the part to be soldered of the substrate 7 is also inclinedly detached from the liquid surface of the molten solder 82, and solder cutting is performed. Since only the substrate 7 having a small occupied volume is tilted and detached, the liquid level of the molten solder 82 does not move up and down violently and good solder cutting is performed. Further, the separation speed at the time of pulling up is controlled to an appropriate speed by the motor 63.

While maintaining the detached state of the substrate 7, the entire pallet device 1 is raised by the lifting mechanism of the soldering device to separate the substrate holding unit 3 from the liquid surface of the molten solder 82, and then the motor 63 is reversed. By rotating, the vertical movement means 6 is pulled down by the weight of the inclined frame 5 and the substrate 7 to push down the engagement frame 5 and the substrate 7, thereby bringing the substrate 7 into contact with the positioning surface 32 a of the mounting surface 32. Thereafter, the pallet device 1 is carried out of the soldering device by the transport mechanism.
[Possibility of other embodiments]

  In the above embodiment, the board 7 of the pallet apparatus 1 is tilted and detached by using the motor 63 as the drive source and the lever mechanism that uses the rotation of the lever 62 to transmit the power. Not what you want.

  That is, as long as the claw portion 61a can be pulled upward, the claw portion 61a may be moved up and down directly by configuring the drive source with a direct acting actuator that uses pneumatic pressure or hydraulic pressure. Also, the transmission mechanism may be configured with appropriate existing technologies such as a link, a combination of gears, a rack and pinion, a belt, and a ball screw.

  Furthermore, although the pallet apparatus 1 of the said Example is the structure which hold | maintains and inclines-detaches the board | substrate 7 of 1 sheet, the part to be soldered of the board | substrate 7 is various. For this reason, as means capable of dealing with other types, for example, as shown in FIG. 6, it is possible to change to a pallet device 9 configured by arranging two substrates 7 in parallel. In this case, it is necessary to expand the frame 2 and add a new substrate holding part 3, an engagement frame 5, and a vertical movement means 6. However, since the same components are added, initial costs such as development can be reduced. I can plan. Further, in the drawing, it is easy to change the design so that the substrate 7 corresponding to the four substrates 7 with the substrate holding portion 3 added on the side opposite to the side on which the vertical movement means 6 is arranged (arrow Z side) is compatible with six substrates.

DESCRIPTION OF SYMBOLS 1 Pallet apparatus 2 Frame 21 Suspension plate 22 Suspension arm 3 Substrate holding part 31 Outer frame 31a Flange 32 Mounting surface 32a Positioning groove 32b Through-hole 32c Escape groove 33 Holding plate 4 Inclination mechanism 5 Engagement frame 51 Engagement part 52 Rotation Arm 53 Pin 54 Hooking part 54a Collar part 6 Vertical movement means 61 Linking member 61a Claw part 61b Rail 61c Roller 61d Guide 62 Lever 62a Bearing part 62b Cam follower 63 Motor 63a Cam 7 Substrate 71 Electronic component 72 Lead 8 Solder tank 81 Nozzle 82 Solder 9 Pallet device (Modification)

Claims (7)

In a soldering method of a soldering apparatus that holds a printed circuit board in a pallet device and solders the printed circuit board by moving the pallet device,
After the pallet device is lowered and the printed circuit board is immersed in the solder liquid surface of the molten solder bath, the print device is moved by the tilt mechanism provided in the pallet device while the pallet device is allowed to stand at the immersion position. A solder cutting method for a soldering apparatus, wherein only the printed circuit board is detached from the liquid surface of the molten solder while gradually increasing an inclination angle of the substrate with respect to the solder liquid surface. Detachment from the liquid surface by the tilt mechanism provided in the pallet device ,
The soldering method for a soldering apparatus according to claim 1, wherein the soldering method is performed by raising one end side with the other end side of the opposite ends of the printed circuit board as a fulcrum . A pallet apparatus for use in the solder cutting method according to claim 1 or 2,
A pallet apparatus comprising an inclination mechanism for inclining only a printed circuit board held by the pallet apparatus with respect to a solder liquid surface of a molten solder bath . The tilt mechanism is
An engagement frame that engages with one end of the printed circuit board held by the pallet device;
Vertical movement means for raising and lowering the engagement frame;
The pallet apparatus according to claim 3, comprising: The vertical movement means
A drive source arranged in the pallet device;
A lever on which the drive source acts;
A linkage member that links the lever and the engagement frame;
The pallet apparatus according to claim 4, comprising: The engagement frame is
An engaging portion that engages with one end of the printed circuit board;
An arm extended from the engagement portion to the opposite engagement portion side along both side edges of the printed circuit board;
The pallet apparatus according to claim 4 or 5, characterized by comprising: Arm is
The pallet device according to claim 6, wherein the pallet device is rotatably coupled to the pallet device at a tip portion on the side opposite to the engaging portion.

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