JP2013055296A - Solder printing machine and soldering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cream solder from dropping after it is printed on a printed circuit board having through holes.SOLUTION: The solder printing machine comprises a squeegee 13 for printing cream solder 18 in through holes 21 formed in a printed circuit board 20 through a metal mask 30 having apertures 31, a backup jig 15 which holds the printed circuit board 20 when printing the cream solder 18, a pressure chamber 16 provided corresponding to the through holes 21 of the printed circuit board 20, and an air supply port 17 for applying air to the pressure chamber 16. A positive pressure is applied from the lower surface side of the printed circuit board 20 to the cream solder 18 printed in the through holes 21, thus moving the cream solder 18 to the upper surface side of the printed circuit board 20.

Description

  The present invention relates to a solder printer and a soldering method.

  As a method for soldering a component to a printed circuit board, a method is known in which cream solder is printed at a predetermined position on a printed circuit board using a metal mask, and the component is soldered by heating and melting the solder. Conventionally, such surface mount technology (SMT) is also applied to lead-inserted components.

  Patent Document 1 describes a method of soldering by inserting component leads into through holes of a printed circuit board. The metal mask described in Patent Document 1 is provided with a blindfold having a diameter approximately equal to that of the lead in a part of the through hole. By printing cream solder using such a metal mask, holes having substantially the same diameter as the leads are provided in the cream solder supplied to the through holes. This prevents the cream solder from being pushed out when the lead is inserted into the through hole, and suppresses the solder amount from being insufficient.

  Patent Document 2 describes a method of mounting a surface mounting component and an insertion component on both the front surface and the back surface of a printed circuit board. In patent document 2, when supplying cream solder to the pad on the back surface, cream solder is supplied in advance to the through hole. After that, as with the back surface, cream solder is printed on the pads and through holes on the front surface, and soldering is performed simultaneously on the front and back surfaces.

JP-A-6-305272 Japanese Patent Laid-Open No. 9-27678

  When mounting an insertion component by SMT, it is important to ensure a sufficient amount of solder at the joint between the component and the printed circuit board in order to ensure the reliability of bonding and the visibility of inspection.

  In Patent Document 1, in order to secure a sufficient amount of solder, it is conceivable to enlarge the opening area of the metal mask or increase the thickness of the metal mask. However, when the opening area is enlarged, the solder covers the through hole and is printed widely. When this solder is torn off when melted to become solder balls and adheres to a narrow pitch IC, there is a possibility that a circuit short circuit occurs. Further, when the metal mask thickness is increased, solder may not be transferred onto the printed circuit board, so that a so-called plate missing defect that remains stuck in the metal mask may occur.

  In Patent Document 2, solder is printed on the through hole on both the front surface and the back surface. However, the thickness of the metal mask for preventing defective printing is several hundred μm at most, so it is necessary to increase the thickness of the metal mask when trying to secure the amount of solder necessary for the inserted part. Occurs.

  Also, adjusting the speed and angle of the squeegee to apply the cream solder and trying to secure the solder amount by pushing the cream solder into the through hole, when transporting the printed circuit board to the next process, or When the lead is inserted into the through hole, the cream solder may fall.

  In the printing process using a metal mask, the solder thickness cannot be locally increased only at the place where the insertion part is mounted. Therefore, it may be possible to use an ink jet type or dispenser type solder supply device in combination with the solder printer. However, there is a problem that investment in these apparatuses is required and processing time is increased.

  On the other hand, a method of compensating for the shortage of the solder amount with shaping solder such as chip-type solder is also conceivable. However, there are problems that the dead space on the printed circuit board for mounting the chip-type solder is increased, and the cost of the chip solder that is more expensive than the cream solder is increased.

  The present invention has been made in the background as described above, and an object of the present invention is to provide solder printing capable of preventing the fall of the cream solder after the cream solder is printed on the printed circuit board having the through hole. An apparatus and a soldering method are provided.

  The solder printer according to the first aspect of the present invention includes a squeegee for printing cream solder in a through hole formed in a printed circuit board through a mask having an opening, and a cream printed in the through hole. A pressure application unit that moves the solder to the upper surface side of the printed circuit board. Thereby, the fear of fall of cream solder can be reduced.

  In the solder printer according to the second aspect of the present invention, in the above-described solder printer, the pressure applying unit moves the printed cream solder by applying a positive pressure from the lower surface side of the printed board. It is characterized by this.

  The solder printer according to a third aspect of the present invention further includes a backup jig for holding the printed circuit board when the cream solder is printed in the solder printer, wherein the pressure application unit is configured as described above. It is provided in a backup jig.

  The solder printer according to a fourth aspect of the present invention is the above-described solder printer, wherein the pressure application unit includes a pressure chamber provided corresponding to the through hole of the printed board, and an air in the pressure chamber. And an air supply port for applying.

  A solder printer according to a fifth aspect of the present invention is characterized in that, in the above-described solder printer, one pressure chamber is provided for a plurality of through holes. Thereby, it becomes possible to apply a pressure equally with respect to a several through hole.

  A solder printer according to a sixth aspect of the present invention is characterized in that, in the above-described solder printer, a plurality of pressure chambers are provided corresponding to the plurality of through holes, respectively. This makes it possible to adjust the pressure in accordance with each of the plurality of through holes.

  A solder printer according to a seventh aspect of the present invention is characterized in that, in the above-described solder printer, different pressures are applied corresponding to the shapes of the plurality of through holes. Thereby, in each through-hole, it becomes possible to be in the optimal state which can prevent a cream solder from falling.

  The solder printer according to an eighth aspect of the present invention is the above-described solder printer, wherein the pressure application unit applies a negative pressure to the printed cream solder from the upper surface side of the printed board. It is what.

  A solder printer according to a ninth aspect of the present invention is the above-described solder printer, wherein a sensor for observing whether or not the cream solder printed in the through hole protrudes from a lower surface of the printed board. It is characterized by comprising. Thereby, it becomes possible to prevent the cream solder from falling more reliably.

  The solder printer according to a tenth aspect of the present invention is the above solder printer, wherein the cream solder printed in the through hole moves from the through hole to the vicinity of the through hole on the printed circuit board. The solder printing apparatus according to claim 1, further comprising a sensor for observing whether or not it has been performed. As a result, it is possible to reliably prevent the cream solder from falling.

  A soldering method according to an eleventh aspect of the present invention is a soldering method for soldering a lead-inserted component into a through hole formed in a printed circuit board, printing cream solder in the through hole, The cream solder is moved to the upper surface side of the printed circuit board, the cream solder is moved to the upper surface side of the printed circuit board, the lead is inserted into the through hole, and the cream solder is heated. To do. Thereby, the fear of fall of cream solder at the time of conveyance of a printed circuit board or lead insertion can be controlled.

  A soldering method according to a twelfth aspect of the present invention is the soldering method described above, wherein the cream solder is moved to the upper surface side of the printed circuit board so that the cream solder does not protrude from the lower surface of the printed circuit board. It is characterized by. Thereby, it becomes possible to prevent the cream solder from falling more reliably.

  A soldering method according to a thirteenth aspect of the present invention is the soldering method as described above, wherein the cream solder is moved to the vicinity of the through hole on the printed circuit board so that the cream solder does not remain in the through hole. It is characterized by making it. As a result, it is possible to reliably prevent the cream solder from falling.

  A soldering method according to a fourteenth aspect of the present invention is the soldering method described above, wherein a positive pressure is applied from the lower surface side of the printed circuit board or a negative pressure is applied from the upper surface side of the printed circuit board. The cream solder is moved.

  ADVANTAGE OF THE INVENTION By this invention, the solder printing apparatus and soldering method which can prevent the fall of the cream solder after printing cream solder on the printed circuit board which has a through hole can be provided.

1 is a diagram illustrating a configuration of a solder printing apparatus according to a first embodiment. FIG. 4 is a diagram for explaining the operation of the solder printer according to the first embodiment. FIG. 4 is a diagram for explaining the operation of the solder printer according to the first embodiment. FIG. 4 is a diagram for explaining the operation of the solder printer according to the first embodiment. FIG. 4 is a diagram for explaining the operation of the solder printer according to the first embodiment. FIG. 4 is a diagram for explaining the operation of the solder printer according to the first embodiment. FIG. 4 is a diagram for explaining the operation of the solder printer according to the first embodiment. It is a figure explaining the soldering method which concerns on Embodiment 1. FIG. It is a figure explaining the soldering method which concerns on Embodiment 1. FIG. It is a figure explaining the soldering method which concerns on Embodiment 1. FIG. It is a figure explaining the soldering method which concerns on Embodiment 1. FIG. It is a figure explaining the soldering method which concerns on Embodiment 1. FIG. It is a figure explaining the soldering method which concerns on Embodiment 1. FIG. It is a figure which shows the structure of the solder printing apparatus which concerns on Embodiment 2. FIG. It is a figure which shows the comparative example of the soldering method. It is a figure which shows the comparative example of the soldering method. It is a figure which shows the comparative example of the soldering method. It is a figure which shows the comparative example of the soldering method. It is a figure which shows the comparative example of the soldering method.

  The present invention relates to a technique of printing a cream solder at a predetermined position on a printed board using a metal mask, soldering the component by heating and melting the solder, and soldering the component. By extruding the cream solder supplied on the through hole to the upper surface side of the printed circuit board, the solder during transportation is prevented from dropping.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description explains the embodiment of the present invention, and the present invention is not limited to the following embodiment. For clarity of explanation, the following description is omitted and simplified as appropriate. Moreover, those skilled in the art can easily change, add, and convert each element of the following embodiments within the scope of the present invention.

Embodiment 1 FIG.
It is a figure which shows the structure of the solder printing apparatus which concerns on Embodiment 1 of this invention. As shown in FIG. 1, the solder printing apparatus according to the first embodiment includes a conveyor 10, a side clamp 11, an upper surface clamp 12, a squeegee 13, a guide rail 14, and a backup jig 15.

  In FIG. 1, the pair of conveyors 10 extends in the front-rear direction. The pair of conveyors 10 abuts the left and right edges of the lower surface of the printed circuit board 20 on which the cream solder is printed. The printed circuit board 20 is conveyed by the conveyor 10 being rotated by a rotation mechanism (not shown).

  The side clamp 11 fixes the printed circuit board 20 from the side surface when the cream solder 18 is printed. Note that the side clamp 11 also serves as a guide rail for the conveyor 10.

  The upper surface clamp 12 is in contact with the upper surface side of the printed circuit board 20 and performs positioning. Further, the upper surface clamp 12 serves to fix the printed circuit board 20 to the backup jig 15 when the cream solder 18 is moved to the upper surface side of the printed circuit board 20 through the through holes 21 as described later. In the example shown in FIG. 1, the L-shaped upper surface clamp 12 rotates to contact the upper surface of the side clamp 11 and the upper surface of the printed circuit board 20, thereby fixing the printed circuit board 20 and the backup jig 15.

  The squeegee 13 is movably held on the guide rail 14. The guide rail 14 is disposed above the printed circuit board 20. The guide rail 14 extends in the left-right direction in parallel with the printed circuit board 20. The squeegee 13 moves along the direction in which the guide rail 14 extends.

  The backup jig 15 is a rectangular plate member. The backup jig 15 holds the lower surface of the printed circuit board 20 so that the printed circuit board 20 does not bend when the cream solder 18 is printed on the printed circuit board 20.

  The backup jig 15 has a pressure chamber 16 and an air supply port 17. The pressure chamber 16 is provided corresponding to the through hole 21 provided in the printed circuit board 20. In the example shown in FIG. 1, one pressure chamber 16 is provided for a plurality of through holes 21. Thereby, pressure can be applied uniformly to the plurality of through holes 21 on the printed circuit board 20. The air supply port 17 is provided with a pressure regulator (not shown). The pressure in the pressure chamber 16 is adjusted by the pressure regulator.

  By supplying air from the air supply port 17 to the pressure chamber 16, the pressure in the pressure chamber 16 becomes a positive pressure higher than the pressure (atmospheric pressure) on the upper side of the printed circuit board 20. By applying a positive pressure from the lower surface side of the printed circuit board 20, the cream solder 18 can be moved to the upper surface side of the printed circuit board 20 through the through hole 21. That is, the pressure application unit includes the pressure chamber 16 and the air supply port 17.

  A pressure may be individually applied to each through hole 21. For example, a separate pressure chamber 16 can be provided for each through hole 21. Moreover, it is preferable to change the applied pressure according to the size, thickness, etc. of the through hole 21. Thereby, in each through-hole 21, it becomes possible to set it as the optimal state in which the cream solder 18 does not fall separately.

  The metal mask 30 is disposed between the squeegee 13 and the printed board 20. The metal mask 30 has an opening 31 formed corresponding to the through hole 21 of the printed circuit board 20. The cream solder 18 is printed in the through hole 21 by placing the metal mask 30 on the printed circuit board 20 and pushing the cream solder 18 into the opening 31 with the squeegee 13.

  Although not shown here, a camera for aligning the printed circuit board 20 and the metal mask 30 may be provided.

  Here, the operation of the solder printer according to the first embodiment will be described with reference to FIGS. As shown in FIG. 2A, the upper surface clamp 12 rotates and contacts the upper surface of the side clamp 11. The upper surface clamp 12 extends from the side clamp 11 to the upper side of the inner printed board 20.

  Thereafter, when the backup jig 15 moves upward, the printed circuit board 20 is separated from the conveyor 10, and the printed circuit board 20 contacts the upper surface clamp 12. Then, the left and right side clamps 11 respectively move to the printed circuit board 20 side and come into contact with the left and right surfaces of the printed circuit board 20 facing each other. Thereby, the printed circuit board 20 is fixed.

  Next, as shown in FIG. 2B, the upper surface clamp 12 is retracted from the upper side of the printed board 20. Then, the conveyor 10 holding the printed circuit board 20, the side clamp 11, and the backup jig 15 are raised, and the printed circuit board 20 comes into contact with the metal mask 30. At this time, alignment is performed so that the opening 31 of the metal mask 30 is positioned on the through hole 21 of the printed circuit board 20.

  Then, as shown in FIG. 2C, the cream solder 18 is pressed while moving the squeegee 13 along the surface of the metal mask 30. Then, the cream solder 18 is pushed out onto the printed circuit board 20 through the opening 31. Since the printed circuit board 20 is held by the backup jig 15 when the cream solder 18 is printed, the printed circuit board 20 does not bend.

  By adjusting the moving speed of the squeegee 13, the inclination with respect to the metal mask 30, the number of reciprocations, etc., an appropriate amount of solder can be ensured. As shown in FIG. 2C, the cream solder 18 printed on the printed circuit board 20 enters the through hole 21 and reaches the lower surface side of the printed circuit board 20.

  The metal mask 30 having a thickness conventionally used can be used. Therefore, the problem of so-called plate missing failure that the cream solder 18 is clogged in the opening 31 of the metal mask 30 does not occur.

  Thereafter, as shown in FIG. 2D, the conveyor 10, the side clamp 11, and the backup jig 15 are lowered while the printed board 20 is held, so that the metal mask 30 is separated from the upper surface of the printed board 20. Then, the upper surface clamp 12 rotates again and comes into contact with the upper surface of the side clamp 11 and the upper surface of the printed circuit board 20. The printed circuit board 20 is fixed to the backup jig 15 by the upper surface clamp 12.

  Then, positive pressure is applied to the cream solder 18 in the through hole 21 by supplying air from the air supply port 17. As a result, as shown in FIG. 2E, the cream solder 18 protruding to the lower surface side of the printed circuit board 20 is pushed out to the upper surface side of the printed circuit board 20.

  Pressure is applied until the cream solder 18 does not protrude from the lower surface of the printed circuit board 20. The state of the cream solder 18 can be observed using a camera used when the metal mask 30 and the printed circuit board 20 described above are aligned. Or you may provide the sensor which detects the state in which the cream solder 18 does not protrude from the lower surface of the printed circuit board 20 separately.

  When the cream solder 18 does not protrude from the lower surface of the printed circuit board 20, the supply of air to the pressure chamber 16 is stopped, and the upper surface clamp 12 is rotated and retracted from the upper surface side of the printed circuit board 20 as shown in FIG. 2F. To do. Further, the backup jig 15 moves downward away from the printed circuit board 20. Further, the side clamps 11 arranged on the left and right sides of the printed circuit board 20 move in directions away from the printed circuit board 20, respectively. As a result, the printed circuit board 20 is held on the conveyor 10 and is dispensed.

  Here, a soldering method using the solder printing apparatus according to the first embodiment will be described with reference to FIGS. 3A to 3C show a solder printing and pressing process using the above-described solder printing apparatus. FIG. 3D shows a component mounting process for mounting the lead-inserted component 40. FIG. 3E shows a reflow process for heating the solder supplied into the printed circuit board 20. FIG. 3F is a diagram illustrating a state where soldering is completed.

  As shown in FIGS. 3A to 3B, cream solder 18 is printed on printed circuit board 20 through metal mask 30 using squeegee 13. At this time, when a necessary amount of solder is pushed into the through hole 21, the shape of the cream solder 18 becomes a shape protruding from the lower surface of the printed circuit board 20 as shown in FIG. 3B.

  Thereafter, the metal mask 30 is separated from the printed circuit board 20. Then, immediately after the cream solder 18 is printed, as shown in FIG. 3C, pressure is applied from the lower surface side of the printed circuit board 20 to move the cream solder 18 in the through hole 21 to the upper surface side of the printed circuit board 20. Thereby, the cream solder 18 does not protrude from the lower surface of the printed circuit board 20, and the substantially spherical cream solder 18 is formed on the upper surface side of the printed circuit board 20. The through hole 21 is filled with cream solder 18.

  Thereafter, the printed circuit board 20 is conveyed to a component mounting process. As described above, the cream solder 18 does not protrude from the lower surface of the printed circuit board 20, and a substantially spherical cream solder is formed on the upper surface side of the printed circuit board 20. For this reason, the possibility that the cream solder 18 being transported falls during the component mounting process is reduced.

  Then, as shown in FIG. 3D, in the component mounting process, the connector 40 having the lead 41 which is an example of the inserted component is inserted into the through hole 21. When the lead 41 is inserted, the lead 41 is inserted into the cream solder 18 so as to push the cream solder 18 up to a position approaching the upper surface of the printed circuit board 20. Thereafter, in the through hole 21, the lead 41 advances while pushing out the cream solder 18 to the lower surface side of the printed circuit board 20.

  When the lead 41 reaches the final insertion end position, the cream solder 18 is slightly attached to the tip of the lead 41 as shown in FIG. 3E. And the printed circuit board 20 of this state is conveyed by the reflow heating process, and the cream solder 18 is heated. As described above, since the cream solder 18 is slightly attached to the tip of the lead 41, the cream solder 18 does not fall even if vibration occurs during conveyance in the reflow heating process.

  The cream solder 18 overflowing from the through hole 21 is sucked into the through hole 21 due to the surface tension of the molten solder that appears after melting, and a balanced fillet shape is formed as shown in FIG. Thereby, a sufficient amount of solder can be ensured, and the printed circuit board 20 and the connector 40 can be satisfactorily joined.

  Here, a comparative example of the soldering method will be described with reference to FIGS. 5A-5B show the solder printing process. FIG. 5C shows a component mounting process for mounting the lead-inserted component 40. FIG. 5D shows a reflow heating process for heating the solder supplied into the printed circuit board 20. FIG. 5E is a diagram illustrating a state in which soldering is completed. In this comparative example, the cream solder 18 is not pushed out to the upper side of the printed circuit board 20 as in the first embodiment.

  As shown in FIGS. 5A to 5B, when a necessary amount of solder is pushed into the through hole 21, the cream solder 18 has a shape protruding from the lower surface of the printed circuit board 20 as shown in FIG. 5B. In this state, the printed circuit board 20 is transported to the component mounting process. Since the cream solder 18 protrudes from the lower surface of the printed circuit board 20, the cream solder 18 may drop due to vibration during conveyance to the component mounting process.

  Then, as shown in FIG. 5C, the lead 41 of the connector 40 is inserted into the through hole 21 in the component mounting process. When the lead 41 is inserted, the cream solder 18 protruding from the inside of the through hole 21 and the lower surface of the printed board 20 is pushed out to the lead 41.

  As a result, as shown in FIG. 5D, a large amount of cream solder 18 is hung from the tip of the lead 41 and conveyed to the reflow process. The cream solder 18 adhering to the tip of the lead 41 is hung only by the adhesive force of the cream solder 18 acting on the tip of the lead 41 having a small area. For this reason, the danger that the cream solder 18 falls during the conveyance to the reflow process is further increased. If the cream solder 18 falls in the middle of conveyance, the solder amount between the printed circuit board 20 and the connector 40 becomes insufficient as shown in FIG.

  Compared with this comparative example, in the soldering method according to the first embodiment, the amount of the cream solder 18 adhering to the tip of the lead 41 is an amount that can be conveyed to the next step without dropping due to its own adhesiveness only. It becomes.

  As described above, in the solder printer according to the first embodiment, the pressure for moving the cream solder 18 to the upper surface of the printed circuit board 20 is applied to the backup jig 15 for preventing the printed circuit board 20 from being bent during printing. An application unit was provided. Thereby, the cream solder 18 can be moved to the upper surface side of the printed circuit board 20 immediately after the cream solder 18 is printed. Thereby, the quantity of the cream solder 18 adhering to the tip of the lead 41 can be suppressed, and it becomes possible to prevent the cream solder 18 from dropping due to vibration during conveyance.

  In the above-described example, the pressure application unit pushes out through the through hole 21 and the upper surface side of the printed circuit board 20 so as not to protrude from the lower surface of the printed circuit board 20, but the present invention is not limited to this. For example, the cream solder 18 may be completely pushed out of the through hole 21 and moved to the vicinity of the through hole 21 on the upper surface of the printed circuit board 20. Even if the cream solder 18 is completely extruded from the through hole 21, when the cream solder 18 is heated and melted, it is drawn into the through hole 21 due to surface tension.

  In order to observe whether or not the cream solder 18 is completely pushed out of the through hole 21 and moved to the vicinity of the through hole 21 on the printed circuit board 20, a pressure sensor for monitoring the pressure in the pressure chamber 16 may be provided. .

Embodiment 2. FIG.
A solder printing apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a diagram illustrating a configuration of a pressure application unit of the solder printing apparatus according to the second embodiment. Since the configuration other than the pressure applying unit can be the same as that of the solder printing apparatus shown in FIG.

  The pressure application unit according to the second embodiment applies a negative pressure whose internal pressure is lower than the atmospheric pressure to the cream solder 18 from the upper surface side of the printed circuit board 20 after the cream solder 18 is printed. Thereby, the cream solder 18 protruding from the lower surface of the printed circuit board 20 can be pulled out to the upper surface side, and the cream solder 18 can be prevented from dropping due to vibration during conveyance. In addition, the pressure application part which applies a negative pressure may be provided in a solder printer, and may be provided outside a solder printer.

DESCRIPTION OF SYMBOLS 10 Conveyor 11 Side clamp 12 Upper surface clamp 13 Squeegee 14 Guide rail 15 Backup jig 16 Pressure chamber 17 Air supply port 18 Cream solder 20 Printed circuit board 21 Through hole 30 Metal mask 31 Opening 40 Connector 41 Lead

Claims (14)

A squeegee for printing cream solder in a through-hole formed in a printed circuit board through a mask having an opening,
A pressure application unit for moving the cream solder printed in the through hole to the upper surface side of the printed circuit board;
A solder printing apparatus comprising:   2. The solder printing apparatus according to claim 1, wherein the pressure application unit moves the printed solder paste by applying a positive pressure from the lower surface side of the printed circuit board. When printing the cream solder, further comprising a backup jig for holding the printed circuit board,
The solder printing apparatus according to claim 1, wherein the pressure application unit is provided in the backup jig. The pressure application unit is
A pressure chamber provided corresponding to the through hole of the printed circuit board;
An air supply port for applying air to the pressure chamber;
The solder printing apparatus according to claim 1, comprising:   The solder printing apparatus according to claim 4, wherein one pressure chamber is provided for a plurality of through holes.   The solder printing apparatus according to claim 4, wherein a plurality of pressure chambers are provided corresponding to the plurality of through holes, respectively.   The solder printing apparatus according to claim 6, wherein different pressures are applied corresponding to the shapes of the plurality of through holes.   The solder printing apparatus according to claim 1, wherein the pressure application unit applies a negative pressure to the printed cream solder from an upper surface side of the printed circuit board.   The solder printing according to claim 1, further comprising a sensor for observing whether or not the cream solder printed in the through hole protrudes from a lower surface of the printed board. apparatus.   10. The sensor according to claim 1, further comprising a sensor that observes whether or not the cream solder printed in the through hole has moved from the through hole to the vicinity of the through hole on the printed circuit board. The solder printing apparatus described in 1. A soldering method for soldering an inserted part with a lead to a through hole formed in a printed circuit board,
Printing cream solder in the through hole,
Move the cream solder to the upper surface side of the printed circuit board,
After moving the cream solder to the upper surface side of the printed circuit board, the lead is inserted into the through hole,
A soldering method comprising heating the cream solder.   The soldering method according to claim 11, wherein the cream solder is moved to the upper surface side of the printed circuit board so that the cream solder does not protrude from the lower surface of the printed circuit board.   The soldering method according to claim 11 or 12, wherein the cream solder is moved to the vicinity of the through hole on the printed circuit board so that the cream solder does not remain in the through hole.   The cream solder is moved by applying a positive pressure from the lower surface side of the printed circuit board or by applying a negative pressure from the upper surface side of the printed circuit board. Soldering method as described in paragraph.

Images