JP5372863B2 - Soldering apparatus and soldering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in the conventional soldering with a large substrate in which: soldering cannot be completed because a printed substrate is curved; soldering jet splatters because molten solder is too close to the printed substrate; and the printed substrate and components are damaged because a nozzle touches a surface-mounted component. <P>SOLUTION: A soldering apparatus comprises: a jet pump 6 for sucking molten solder up from a solder bath 5 where the molten solder is pooled and jetting it; and a nozzle 3 for guiding the sucked molten solder to a proper position for soldering. The soldering apparatus further comprises a wiring 15 for connecting wiring formed in a printed substrate 2 and the soldering bath 5. Electrical conduction in a circuit through the wiring helps a status to be detected in which an X-Y-Z table 7 controls a position of the nozzle or the printed substrate and the molten solder coming out of the nozzle contacts a through hole 12. When the conduction is detected, position control is conducted to adjust the X-Y-Z table at a proper position. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a soldering apparatus and a soldering method suitable for soldering an electronic component mounted on a printed circuit board.

  In general, an electronic device is assembled by soldering an electronic component to an electrode of a printed board on which wiring for causing an electronic circuit to function is provided. Soldering an electronic component and attaching it to the printed circuit board is called component mounting on the printed circuit board.

  The main types of components to be mounted on the printed circuit board are: a solder paste is applied to the electrodes provided on the surface of the printed circuit board, the components are mounted on the applied paste, and then the entire printed circuit board is reflowed. The type of parts called surface mount parts that are heated in a heating furnace called solder and melted to perform soldering, and electrodes called through holes that are plated inside the holes drilled in the printed circuit board There are two types of components, called insert mounting components, in which leads, ie, electrodes, are inserted and soldered by applying a molten solder jet thereto.

  In these two types of parts, as described above, since the soldering method is greatly different, the process of mounting the electronic parts on the electronic device is divided into two processes, that is, the surface mounting part soldering process and the insertion mounting part soldering process. It is common to implement separately.

  Since mounting of surface mount components supplies paste solder to the electrodes on the surface of the printed circuit board by plate printing, mounting the surface mount components after mounting the insert components causes the electrodes of the insert components to protrude from the printed circuit board. Therefore, since the solder paste plate printing is obstructed, the soldering of the insertion mounting component is often performed after the soldering of the surface mounting component.

  In recent years, as the performance of electronic devices has been improved, components mounted on a printed circuit board have been increasing in density, and it is not uncommon for surface mounted components to be mounted on both sides of a printed circuit board. In the printed circuit board on which the surface mounting components are mounted on both sides, after mounting the surface mounting component on one side, the surface mounting component on the opposite side is mounted, and then the insertion component is mounted.

  As described above, the soldering of the insertion part is performed by applying a molten solder jet to the through-hole electrode of the printed circuit board. When the surface mount component is mounted only on one side, it was possible to perform soldering collectively by applying a molten solder jet to the entire printed circuit board surface on which the surface mount component is not mounted. A soldering apparatus having a mechanism capable of batch soldering is generally called a flow soldering apparatus.

  On the other hand, in the case of a printed circuit board in which surface-mounted components are mounted on both sides (such a printed circuit board is referred to as a double-sided mounted printed circuit board), the insertion component is applied by applying a molten solder jet over the entire printed circuit board as in a flow device. When soldering is performed, the surface-mounted component that has been mounted is peeled off by molten solder or damaged by heat.

  For this reason, when soldering an insertion-mounted component onto a board where the surface-mounted component is mounted on both sides of the printed circuit board, avoid the location where the surface-mounted component is soldered, but only the electrode location of the insertion-mounted component. A method of selectively soldering is required.

  As a general method of selectively soldering the electrode location of the insertion component, a printed circuit board is placed on a jig that opens the electrode location (through hole) of the insertion component, called a pallet jig, and the surface mount component is masked (covered). And using a flow device to perform soldering while protecting the surface-mounted components.

  However, the soldering method of the inserted part using the pallet jig in this flow apparatus has the following problems.

  Problem (1) usually requires that the molten solder jet port (nozzle) in the flow apparatus be set at a distance of 5 to 10 mm from the printed circuit board so that optimum soldering can be performed. Because of this restriction, the thickness of the pallet is determined so that it does not touch the nozzle, and the height of the surface-mounted component on the soldering surface is determined to match it, so the component height of the surface-mounted component on the soldering surface Is limited to 3 to 5 mm.

  The problem (2) is that the molten solder jet applied to the solder electrode of the inserted part is disturbed by the pallet, so that especially in the electrode near the part covered with the pallet, a soldering defect such as a bridge (short circuit) is likely to occur. is there.

  In recent years, in order to avoid the problems (1) and (2), a device (local soldering device) for locally soldering the electrode of an insertion part, for example, as in the prior art described in [Patent Document 1] is there.

  Such a local soldering apparatus can avoid the above problems (1) and (2) because the soldering electrode of the insertion part is selectively soldered using a local nozzle (solder jet port).

JP 2001-347366 A

  However, in the local soldering apparatus, when performing soldering of electronic components, in particular, a large board such as a back boat used for communication between a parent board of an electronic computer called a mother board and individual printed boards, Due to the warping that has occurred on the printed circuit board during soldering, the solder is not sprayed due to the jet of molten solder not touching the electrodes of the printed circuit board. There is a problem that the nozzle tends to come into contact with the surface mount component in the vicinity of the printed circuit board, the electrode of the insertion part or the soldering part, or to damage the printed circuit board or the part.

  An object of the present invention is to provide a soldering apparatus and a soldering method capable of avoiding problems such as an unsoldered state, blown up solder, contact with a surface-mounted component, and damage to a printed circuit board or component.

  In order to achieve the above object, the present invention uses a wiring in a printed circuit board, such as a ground, to detect a current flowing from the printed circuit board to a jet solder during soldering when soldering an insertion mounted component by a local soldering apparatus. Thus, by obtaining information that the molten solder jet contacts the printed circuit board and feeding it back to the nozzle position, it is possible to perform soldering at an appropriate nozzle position even if the printed circuit board is warped.

  According to the present invention, an unsoldered state where the jet of molten solder does not touch the electrodes of the printed circuit board, or conversely, the solder blows up when the molten solder jet is too close to the printed circuit board. This makes it possible to avoid problems such as damage to the printed circuit board and components by contacting the electrodes or surface-mounted components in the vicinity of the soldering. Further, by monitoring the current as a secondary effect of using the present invention, it is possible to confirm the completion of soldering and the state of wiring in the printed circuit board.

The perspective view which shows the whole structure of the local soldering apparatus which is one Example of this invention. The longitudinal cross-sectional view of the local soldering apparatus of a present Example. The figure explaining a motion of a XYZ table. The longitudinal cross-sectional view which shows the whole block diagram of a multi-local soldering apparatus. The figure which shows the example of a round nozzle. The figure which shows the example of a square nozzle.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a local soldering apparatus according to the present embodiment, and FIG. 2 is a longitudinal sectional view of the local soldering apparatus according to the present embodiment.

  The local soldering apparatus is an apparatus that performs soldering using an insertion mounting component 1 mounted on a printed board 2 and a molten solder 4 that jets the printed board 2 from a nozzle 3.

  As shown in FIGS. 1 and 2, the soldering apparatus is attached to a solder bath 5, a solder jet pump 6 provided to pull up and jet molten solder from the solder bath 5, and the tip of the solder jet pump 6. The nozzle 3 is configured. The solder bath 5 is placed on an XYZ table 7 that controls the position of the printed circuit board 2 or the soldering nozzle 3 at an appropriate position, and is connected to the XYZ table 7 by a signal line 14. The position of the XYZ table 7 in the X-axis, Y-axis, and Z-axis directions is controlled by a control signal from the control computer 9 (hereinafter referred to as control PC 9) as shown in FIG. The attached jet is controlled. A wiring 15 is attached to the solder tank 5, and the wiring 15 is connected to a control PC.

  A surface mounting component 11 is mounted on the back side of the surface of the printed circuit board 2 where the insertion mounting component 1 is mounted, and the insertion mounting component 1 is attached to a location different from the location where the surface mounting component 11 is mounted. It is done.

  The printed board 2 is provided with a through hole 12 for inserting an electronic component as the insertion mounting component 1, and the lead 10 of the electronic component is inserted into the through hole 12. Next, a flux for soldering is applied. The flux is applied by spraying or the like to the soldering site by a program prepared in advance. After applying the flux, depending on the thickness of the printed circuit board and the electronic parts to be soldered, it may be possible to reduce soldering problems by heating the printed circuit board to some extent by performing preheating with a heater for a set time. After the flux has dried to some extent, soldering is performed.

  A wiring 8 for detecting whether or not the soldering apparatus and the through hole 12 for soldering the printed board 2 are in contact with each other is attached to the printed board 2. The wiring 8 is attached to a power supply pattern portion of the wiring pattern 13 in the printed circuit board such as a ground connected to the through hole 12. The wiring 8 is connected to the control PC 9.

  Soldering is performed by jetting molten solder from a nozzle 3 having a hole diameter of φ5 to 20 mm (cylinder with a cavity through which molten solder passes) to a height of about 3 mm, and flux is applied to nozzle 3 from which molten solder 4 has been jetted. This is performed by approaching the through hole 12 portion of the printed circuit board 2 from which the lead 10 of the inserted mounting component 1 protrudes, and applying a jet of molten solder 4 to the through hole 12 from the lower side (back side).

  Once the jet of molten solder 4 is applied to the printed circuit board 2, it is possible to move the nozzle 3 in the XY direction and perform continuous soldering. When the printed circuit board 2 is placed on the XYZ table 7, it is also possible to move the printed circuit board 2 in the XY direction and continuously solder it. The position control of the nozzle 3 is executed by a program created based on the coordinate position of the insertion component 1 to be soldered in advance.

  Since the protrusion of the lead 10 of the insertion mounting component 1 of the printed circuit board 2 is 1 to 3 mm and the jet of the molten solder 4 is about 3 mm, the position of the nozzle 3, the molten solder 4 and the printed circuit board 2 in the vertical direction at this time The relationship is that when the protrusion of the lead 10 is close to the upper limit of 3 mm, the molten solder 4 is attached to the printed circuit board 2 unless the nozzle 3 is brought close to the printed circuit board 2 until the nozzle 3 comes into contact with the tip of the protrusion of the lead 10. I can't. On the other hand, if the nozzle 3 is too close to the printed circuit board 2, the nozzle 3 and the protrusion of the component lead 10 come into contact with each other, which may cause component damage.

  Therefore, strict control is required for the vertical position (Z-axis) control of the nozzle 3. In addition, in the vertical position (Z-axis) control of the nozzle 3, it is necessary to consider the warpage of the printed circuit board 2 generated by heat applied in the printed circuit board manufacturing process or the surface mounting process.

  The point which enables soldering at the proper nozzle 3 position in consideration of this warpage will be described. The local soldering apparatus forms a circuit so that the wiring 8 for detecting the contact between the molten solder 4 and the through hole 12 is connected to the wiring pattern 13 in the printed circuit board.

  Assuming that the printed circuit board 2 is warped when the molten solder 4 is jetted from the tip of the nozzle 3 and is raised to a setting position to be soldered to the printed circuit board 2, the nozzle 3 is set at the set position. Before coming to the nozzle 3, the nozzle 3 comes into contact with the tips of the printed circuit board 2 and the lead 10 of the insertion mounted component 1, and the component is damaged.

  However, in the local soldering apparatus of this embodiment, when the jet of molten solder 4 comes into contact with the printed circuit board 2, the circuit formed by the wiring 8 and the like is closed, so the jet of molten solder 4 comes into contact with the printed circuit board 2. Since it is possible to detect the occurrence of the failure and to stop the ascending (Z-axis) control by the detection signal, it is possible to prevent the parts from being damaged and to be soldered at an appropriate position.

  On the other hand, when the printed circuit board 2 is warped, the circuit formed by the wiring 8 and the like is not closed even when the nozzle 3 is raised to the set position. When the board rises more than the set position, the jet of the molten solder 4 and the printed circuit board 2 come into contact with each other, and the circuit formed by the wiring 8 and the like is closed, so the jet of the molten solder 4 is printed. The contact with the substrate 2 can be detected, and the ascending (Z-axis) control is stopped by the detection signal, thereby enabling soldering at an appropriate position.

  The position in the Z direction of the nozzle 3 to be soldered differs depending on the thickness of the component to be soldered and the printed board, so that it is +0.5 mm above the position where the jet of the molten solder 4 and the printed board 2 are in contact with each other. By controlling the position of the soldering at the position, it becomes possible to perform soldering at the proper nozzle 3 position, and the management of the soldering time is also performed in a specified time from the time when the jet of the molten solder 4 and the printed circuit board 2 contact each other. By maintaining the intermediate nozzle position and shifting to the next operation after the set time has elapsed, it becomes possible to manage the soldering time strictly.

  However, since the local soldering apparatus of the present embodiment uses a wiring pattern in the printed circuit board for Z-axis control, the through hole 12 to be soldered is a circuit that can be electrically connected to the soldering apparatus. It must be. In general, in a circuit that constitutes a printed circuit board, the wiring of the power supply pattern such as the ground is the most, so in this power supply pattern such as the ground, a wiring for detecting contact between the molten solder and the printed circuit board is prepared. Efficient soldering is possible.

  After the proper Z-axis position of the insertion mounting component 1 or the printed circuit board 2 is confirmed, the nozzle 3 is controlled in the XY direction within a range in which the warpage of the printed circuit board 2 does not affect, and other through holes 12 are continuously formed. You may make it solder.

If there is no through-hole 12 for confirming the Z-axis control of the ground pattern or the like in the insertion mounting component 1 to be soldered or in the vicinity of the component, a dummy through is close to the corresponding component at the time of designing the printed circuit board in advance. It is necessary to provide holes 12 or pad electrodes.
The through hole 12 in this case may be a small diameter through hole instead of a component insertion hole.

  If the wiring pattern 13 formed in the printed circuit board has a defect such as disconnection, it does not function well, and a place other than the through hole 12 electrically connected to the local soldering apparatus is soldered. In this case, since the circuit of the local soldering device and the printed circuit board is not closed, the contact information between the molten solder 4 jetted from the nozzle 3 during the soldering and the printed circuit board 2 is monitored by electrical continuity. It is possible to detect wiring defects such as disconnection and short circuit.

  In the technology of jetting the molten solder 4 from the nozzle 3 and performing soldering in component mounting on the printed circuit board 2, the height of the jet of the molten solder 4 from the nozzle 3 is such as impurities such as flux in the solder, solder oxide, etc. Due to clogging, it is difficult to adjust to a constant height at all times. Conventionally, it was common to visually determine the jet height by visually observing the jet from the side or by applying a jet to a glass plate or the like, but according to the local soldering device of this example, the jet flow The height can be measured easily and accurately. That is, normally, instead of setting the printed circuit board 2 to be soldered, a horizontal metal plate (a metal that does not react with molten solder such as SUS is desirable) is set, and the nozzle 3 to which the molten solder is jetted is defined. When the nozzle 3 is raised while the molten solder 4 is jetted, the circuit of the local soldering device and the printed circuit board 2 is closed. By calculating the distance between the position of the nozzle 3 and the metal plate from the position, the height of the molten solder jet from the nozzle 3 can be measured. In addition, you may provide the metal plate for jet height measurement as a part of local soldering apparatus instead of setting to a printed circuit board set position.

  As described above, by using the wiring pattern 13 and the electrode through hole 12 in the printed circuit board such as the ground, the current flowing from the printed circuit board 2 to the jet solder 4 is monitored at the time of soldering. Since the information that the contact with the printed circuit board 2 is obtained is obtained, the information is fed back to the position of the nozzle 3 to perform soldering at an appropriate position of the nozzle 3 even if the printed circuit board 2 is warped. It becomes possible.

  As a result, an unsoldered state where the jet of molten solder 4 does not touch the electrodes of the printed circuit board 2, or conversely, the solder blows up when the jet of molten solder 4 gets too close to the printed circuit board 2, causing the nozzle 3 to move to the printed circuit board. 2 or the electrode through-hole 12 of the insertion mounting component 1 or the surface mounting component in the vicinity of the soldering contact, thereby avoiding problems such as damage to the printed circuit board 2 or the component.

  In addition, by applying this embodiment, it is possible to detect a defect in the printed circuit board such as a disconnection or a short circuit inherent in the printed circuit board 2 and confirm soldering.

  In the above description, the apparatus for soldering by controlling the nozzle 3 with the XYZ table 7 has been described. However, the position of the nozzle 3 is fixed, and the printed circuit board 2 to be soldered is placed on the XY. Even when the position is controlled by the Z table 7 and soldering is performed, the same effect can be obtained.

  FIG. 4 is a longitudinal sectional view of a local soldering apparatus in which a plurality of local soldering apparatuses shown in FIG. 2 are independently installed.

  A plurality of local soldering portions are provided, and a plurality of nozzles having different shapes are provided as shown in FIGS. The control PC 9 is provided corresponding to each local soldering portion, and the wiring 8 is also provided corresponding to the local soldering portion.

  By installing a plurality of nozzles having different shapes, it is possible to efficiently solder a soldering portion on which a large number of components are mounted. The nozzle position detection devices may be installed individually, but can be combined into one by controlling a plurality of nozzle position detection devices independently.

DESCRIPTION OF SYMBOLS 1 Insert mounting component 2 Printed circuit board 3 Nozzle 4 Molten solder 5 Solder tank 6 Solder jet pump 7 XYZ table 8 Wiring 9 Control PC
10 Lead 11 Surface mount component 12 Through hole 13 Wiring pattern

Claims (6)

  Solder bath for storing molten solder, jet pump for pulling and jetting molten solder from the solder bath, soldering nozzle for guiding the pulled molten solder to an appropriate soldering position, nozzle position or print A soldering apparatus including an XYZ table for controlling a position of a board to an appropriate position and soldering an electronic component to the printed board, and connecting a wiring formed in the printed board and the solder bath The position of the nozzle or the printed circuit board is detected by detecting electrical continuity of the circuit by the wiring that the molten solder jetted from the nozzle is in contact with the wiring formed in the printed circuit board. A soldering apparatus characterized by performing control.   The soldering apparatus according to claim 1, wherein the nozzle or the printed circuit board is moved to an appropriate position by an XYZ table based on contact information between the detected printed circuit board and the molten solder jetted from the soldering nozzle. . Based on the contact information between the detected printed circuit board and the molten solder jetted from the soldering nozzle, the soldering time after the solder jetted from the nozzle contacts the printed circuit board is measured, and the jet is stopped after the set time has elapsed. The soldering apparatus according to claim 1, wherein the soldering is performed in an appropriate soldering time by moving the XYZ table from the soldering position and stopping the soldering.   A solder bath for storing molten solder, a jet pump for pulling and jetting molten solder from the solder bath, and a soldering nozzle for guiding the pulled molten solder to an appropriate soldering position Provided with other wiring that connects the wiring formed on the solder bath and the solder bath, the nozzle position or the position of the printed circuit board is controlled by an XYZ table, and the molten solder jetted from the nozzle is placed in the printed circuit board Soldering, wherein contact with a formed wiring is detected by electrical continuity of a circuit through the wiring, and when the continuity is detected, the position of the XYZ table is controlled to an appropriate position. Method.   The soldering method according to claim 4, wherein a wiring defect in the printed circuit board is detected by monitoring contact between the wiring formed in the printed circuit board and the molten solder jetted from the nozzle by electrical conduction.   Claim to measure the jet height of the molten solder jetted from the nozzle by checking the contact between the printed circuit board prepared as a reference or a conductive metal plate and the molten solder jetted from the nozzle by electrical conduction Item 5. The soldering method according to Item 4.

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