JP4962459B2 - Component mounting method - Google Patents

Description

  In the present invention, after components having electrodes at both ends are mounted on a substrate on which solder has been applied in advance, the substrate is sent in a certain direction and passed through a reflow furnace, thereby heating and cooling the solder on the substrate. The present invention relates to a component mounting method for mounting components on a substrate.

  When mounting components (chip components) having electrodes at both ends on a substrate by the reflow method, paste-like solder is applied in advance to lands provided on the substrate, and the electrodes at both ends of the component are applied to the components. After mounting each component in contact with the solder on the corresponding pair of lands, the substrate is sent in a certain direction and passed through a reflow furnace. As a result, the paste-like solder is melted and solidified, and each component is mounted on the substrate.

  Among the components mounted on the board by such a reflow-type component mounting method, if the direction in which the electrodes on both ends are aligned with the traveling direction of the board in the reflow furnace, the board moves through the reflow furnace. When traveling, the solder on the land located in the front of the board in the direction of travel starts melting earlier than the solder on the land located in the rear of the direction of travel, and starts solidifying earlier in time. become. For this reason, an unbalance of the force (surface tension and adhesive force) acting on the component occurs between the solder on the land located in the front in the traveling direction and the solder on the land located in the rear in the traveling direction, As a result, the tip of the chip rises from the land in the direction of travel of the substrate, and only the front electrode in the direction of travel is soldered onto the land and the component stands in an inclined position (also called Manhattan phenomenon or tombstone phenomenon) May occur.

Such chip standing is more likely to occur as the part becomes smaller, and countermeasures are important nowadays as parts become lighter and thinner. For this reason, various measures have been taken in the past. For example, Patent Document 1 listed below discloses a technique for adjusting the shape of a land so that surface tension that raises a chip does not occur even when solder melts and solidifies. Has been.
JP 2005-116918 A

  However, since there are an extremely large number of components mounted on the board, it is difficult to adjust the shape of the land for each chip from the viewpoint of cost, and a simpler chip standing prevention method is required. Yes.

  Therefore, an object of the present invention is to provide a component mounting method that can prevent the occurrence of chip standing by a simple method.

In the component mounting method according to claim 1, after mounting components having electrodes at both ends on a substrate on which solder has been applied in advance by a component mounting machine , the substrate is sent in a certain direction and passed through a reflow furnace. This is a component mounting method in which the solder on the substrate is heated and cooled to mount the component on the substrate. Among the components to be mounted on the substrate, the electrodes on both ends are aligned when mounted on the substrate. If the direction of the board is the same as the direction of travel in the reflow furnace and the solder is expected to rise when the solder is heated and melted in the reflow furnace, the board that is predetermined for the component is used. reflow from the mounting position above the defined shift in the direction of arrangement of the electrode is intended to be mounted by the component mounting machine, the substrate passing through the reflow furnace were examined by soldering visual inspection machine, direction in which the electrode is lined with the substrate If the information indicating that the chip was standing after passing through the reflow furnace was sent to the component mounting machine from the soldering appearance inspection device If the same component is mounted on the same location of the substrate and passed through the reflow furnace, the component is predicted to stand up .

  In the component mounting method of the present invention, among the components to be mounted on the substrate, the direction in which the electrodes on both ends are aligned with the traveling direction in the reflow furnace of the substrate when mounted on the substrate, and When the solder is expected to stand when the solder is heated and melted in the reflow furnace, the component is mounted by shifting it from the predetermined mounting position on the substrate in the direction in which the electrodes are arranged. In this way, it is possible to change the balance of the force (surface tension and adhesive force) acting on the component by the solder that contacts both electrodes of the component in a stable direction (a direction in which the chip does not stand up). In addition, it is possible to prevent the occurrence of chip standing.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a component mounting line according to an embodiment of the present invention, and FIGS. 2A, 2B, and 2C illustrate a bonding process between a substrate and an electronic component according to an embodiment of the present invention. FIG. 3 is a flowchart showing the flow of component mounting executed by the component mounting line according to the embodiment of the present invention, and FIG. 4A is a diagram showing normal components in the component mounting line according to the embodiment of the present invention. FIG. 4B is a diagram showing a mounted state, FIG. 4B is a diagram showing a state in which the component stands on the component mounting line in the embodiment of the present invention, and FIG. 5 is a component mounting in the embodiment of the present invention. FIG. 6 is a plan view of a component mounting machine according to an embodiment of the present invention, and FIG. 7 is a transfer head of the component mounting machine according to an embodiment of the present invention. Enlarged front view, figure FIG. 9 is a block diagram showing a control system of a component mounting machine in one embodiment of the present invention, and FIGS. 9A and 9B are views of components in a component mounting process executed by the component mounting machine in one embodiment of the present invention. It is a top view of the board | substrate and components explaining the shift method of a mounting position.

  In FIG. 1, a component mounting line 1 includes a solder printing machine 2, a solder appearance inspection machine 3, a component mounting machine 4, a component mounting inspection machine 5, a reflow furnace 6, and a soldering appearance inspection machine 7.

  The solder printer 2 receives the substrate 8 supplied from the outside by the conveyor 2a, positions it at a predetermined position, and prints (applies) paste solder S on the land 8a on the substrate 8 (FIG. 2A). The solder application process in step ST1 shown in FIG. 3 is carried out of the solder printer 2 by the conveyor 2a.

  The solder appearance inspection machine 3 receives the board 8 carried out from the solder printing machine 2 by the conveyor 3a and positions it at a predetermined position, and shows the appearance (applied state) of the paste-like solder S printed on the board 8. The presence or absence of an abnormality is visually inspected with a camera that does not (step ST2 solder appearance inspection step shown in FIG. 3). As a result, the substrate 8 in which no abnormality is found in the application state of the solder S is unloaded by the conveyor 3a as it is, and the substrate 8 in which the abnormality is found in the application state of the solder S is determined at a predetermined position on the substrate 8. Imprint a defect mark on the

  The component mounting machine 4 receives the substrate 8 transported from the solder appearance inspection machine 3 by the transfer conveyor 4a and positions it at a predetermined position. The component mounting machine 4 places the component P on the substrate 8 on which no defect mark is imprinted by the solder appearance inspection machine 3. Mounting is performed (FIG. 2B, component mounting process in step ST3). Here, the component P is a so-called chip component that has electrodes T at both ends and is surface-mounted on the substrate 8. The component P is coated with paste solder S by the solder printer 2. It is mounted on the pair of lands 8a. When all the components P are mounted at predetermined positions on the substrate 8, the component mounting machine 4 unloads the substrate 8 to the outside by the transfer conveyor 4a.

The component mounting inspection machine 5 receives the substrate 8 transported from the component mounting device 4 by the transfer conveyor 5a and positions it at a predetermined position, and visually recognizes each component P mounted on the substrate 8 by the component mounting device 4 with a camera (not shown). Then, the presence / absence of an abnormality is inspected (component mounting appearance inspection step in step ST4). As a result, the board 8 in which no abnormality is found in the mounting state of the component P is unloaded by the conveyor 5a as it is, and the board 8 in which the abnormality is found in the mounting state of the part P is determined at a predetermined position on the board 8. Imprint a defect mark on the

  The reflow furnace 6 receives the substrate 8 carried out from the component mounting inspection machine 5 by the transfer conveyor 6a, sends it in a certain direction (arrow A shown in FIG. 1), and heats it while moving through the furnace (FIG. 2). (C)) Cooling (solder heating cooling step of step ST5). As a result, the solder S on the substrate 8 is melted and then solidified, whereby the electrodes T at both ends of the component P are soldered onto the pair of lands 8 a of the substrate 8. The board 8 to which the component P is soldered is directly carried out to the outside by the transfer conveyor 6a.

  The soldering appearance inspection machine 7 receives the board 8 carried out from the reflow furnace 6 by the transfer conveyor 7a, and shows the appearance of the solder S of the board 8 heated and cooled in the reflow furnace 6 (soldering state of the component P). Visually inspect with a camera that does not, check for abnormalities. As a result, the board 8 in which no abnormality is found in the soldering state of the component P is unloaded by the conveyor 7a as it is, and the board 8 in which the abnormality is found in the soldering state of the part P A defective mark is impressed at a predetermined position and is carried out (solder appearance inspection step of step ST6). Of the substrates 8 carried out from the soldering appearance inspection machine 7, the substrate 8 on which no defect mark is imprinted becomes the substrate 8 on which component mounting is normally performed in the component mounting line 1.

  The soldering appearance inspection machine 7 also performs an inspection of whether there is a component P standing on a chip on the substrate 8 carried out of the reflow furnace 6. When the soldering appearance inspection machine 7 visually recognizes the component P standing on the substrate 8, information on which position on the substrate 8 and the component P mounted in which direction the chip is standing, It transmits to the component mounting machine 4 via the signal transmission line 9 shown in FIG. As a result, the component mounting machine 4 can obtain information on which position on the substrate 8 and in which direction the component P mounted thereafter caused the chip to stand.

  Here, the chip standing means that the direction in which the electrodes T on both ends of the component P mounted on the substrate 8 are arranged is the direction in which the substrate 8 travels in the reflow furnace 8 (FIGS. 1, 4A, and 4B). 4), the two electrodes T of the component P are not soldered to the corresponding lands 8a as shown in FIG. 4A. As shown in (b), the electrode T behind the substrate 8 in the traveling direction in the reflow furnace 6 is lifted from the land 8a, and only the electrode T ahead in the traveling direction is soldered onto the land 8a. The phenomenon of standing up in an inclined position. In such chip standing, when the substrate 8 travels in the reflow furnace 6, the solder S on the land 8 a located in front of the traveling direction of the substrate 8 is more than the solder S on the land 8 a located behind in the traveling direction. In this case, since melting starts earlier in time and solidification starts earlier in time, the solder S on the land 8a located in the front in the traveling direction and the solder S on the land 8a located in the rear in the traveling direction It is thought that this is caused by an unbalance of forces (surface tension and adhesive force) acting on the component P between the two.

  In the present embodiment, the component mounting process (step ST3 shown in FIG. 3) performed by the component mounting machine 4 of the component mounting line 1 is specifically executed according to the procedure shown in the flowchart shown in FIG. It is possible to prevent the component P from standing up in the heating and cooling process.

Before describing the details of the component mounting process performed by the component mounting machine 4, first, the configuration of the component mounting machine 4 will be described with reference to FIGS. 6, 7, and 8. The component mounting machine 4 includes the above-described transport conveyor 4a on the base 11, and an X-axis direction (FIG. 1 and FIG. 4A), which is the transport direction of the substrate 8 by the transport conveyor 4a, is above the transport conveyor 4a. , (B) is provided with a Y-axis table 12 extending in a direction (Y-axis direction) perpendicular to the horizontal direction (direction along arrow A). Y-axis table 1
2 includes two Y-axis sliders 13 that are movable along the Y-axis table 12 (that is, in the Y-axis direction). Each Y-axis slider 13 includes an X-axis table 14 that extends in the X-axis direction. One end is attached. Each X-axis table 14 is provided with a moving stage 15 that is movable along the X-axis table 14 (that is, in the X-axis direction).

  6 and 7, a transfer head 16 is attached to each moving stage 15, and a plurality of nozzle shafts 17 extend downward in the vertical direction (Z-axis direction) to each transfer head 16. Is provided. A suction nozzle 19 is detachably attached to the lower end portion of each nozzle shaft 17 via a nozzle holder 18.

  In FIG. 6, a plurality of tape feeders 20 that supply the component P to the transfer head 16 are provided side by side in the X-axis direction in the side region of the transport conveyor 4a. The transfer head 16 is provided with a substrate camera 21 with the imaging surface facing downward, and a component camera 22 with the imaging surface facing upward is provided on the base 11.

  In FIG. 8, the component mounting machine 4 includes a transport conveyor drive motor 23 a that drives the transport conveyor 4 a, a Y-axis slider moving mechanism 23 b that moves each Y-axis slider 13 along the Y-axis table 12, and each moving stage 15. A moving stage moving mechanism 23c that moves along the X-axis table 14, a nozzle drive mechanism 23d that individually moves the suction nozzles 19 up and down and rotates around the vertical axis (Z-axis), and suction of the component P to each suction nozzle 19 (pickup) ) A nozzle suction mechanism 23e for performing the operation is provided. The transport conveyor drive motor 23a, the Y-axis slider moving mechanism 23b, the moving stage moving mechanism 23c, the nozzle drive mechanism 23d, and the nozzle suction mechanism 23e are controlled by the control device 24 provided in the component mounting machine 4, and the transport conveyor 4a. The substrate 8 is transported and positioned by means of the above, the component P is picked up by the transfer head 16, and the component P is mounted on the substrate 8. The operation of the board camera 21 and the component camera 22 is controlled by the control device 24, and the imaging results from the board camera 21 and the component camera 22 are input to the control device 24. The storage device 25 connected to the control device 24 stores various data including data on the target mounting position of each component P on the substrate 8 (coordinate data based on the substrate 8).

  In the component mounting process performed by the component mounting machine 4 having such a configuration, the control device 24 first drives the transport conveyor 4a to transport the substrate 8 in the X-axis direction and position it at a predetermined position (steps shown in FIG. 5). ST31). Then, the movement stage 15 is moved relative to the substrate 8 positioned at a predetermined position by the movement of the X-axis table 14 in the Y-axis direction and the movement stage 15 in the X-axis direction. Components that the tape feeder 20 supplies to the suction nozzle 19 provided in the transfer head 16 after image recognition (imaging) of a positioning mark (not shown) on the substrate 8 is performed by the substrate camera 21 that has been positioned (step ST32). P is picked up (step ST33).

  After completing step ST33, the control device 24 moves in the horizontal direction so that the component P sucked by the suction nozzle 19 passes above the component camera 22 (within the field of view of the component camera 22) and moves the component P to the component camera 22. Image recognition (imaging) of the lower surface of P is performed (step ST34). And the data of the target mounting position on the board | substrate 8 of the components P currently picked up are read from the memory | storage device 25 (step ST35).

When the control device 24 reads the data of the target mounting position of the component P from the storage device 25 in step ST35, the control device 24 is currently selected from among the components P that are currently picked up by the suction nozzle 19 and are to be mounted on the substrate 8 from now on. When the electrodes 8 are mounted at the specified mounting positions on the substrate 8 (that is, according to the target mounting position data read from the storage device 25), the direction in which the electrodes T on both ends are aligned in the reflow furnace 6 of the substrate 8 In step ST36, it is determined whether or not there is a chip that is predicted to stand up when the solder S is heated and melted in the reflow furnace 6 in the reflow furnace 6.

In step ST36, the chip standing information of the component P sent from the soldering appearance inspection machine 7 to the component mounting machine 4 via the signal transmission line 9 (as described above, the information on which on the substrate 8 This can be performed based on information on which direction the component P mounted in the position is standing on the chip. That is, as shown in FIG. 9 (a), the substrate 8 is mounted on the substrate 8 according to the target mounting position data read from the storage device 25 in step ST35, and the direction in which the electrodes T are aligned is the progress of the substrate 8 in the reflow furnace 6. Information indicating that the chip standing has occurred after the part P that coincides with the direction (arrow A shown in FIGS. 9A and 9B) has passed through the reflow furnace 6 is obtained from the soldering appearance inspection machine 7. In the case of being sent to the component mounting machine 4, if the same component P is subsequently mounted on the same location on the same substrate 8 and passed through the reflow furnace 6, the component P raises the chip. Can be predicted.

  When the control device 24 of the component mounting machine 4 determines that there is something that is predicted to stand up in step ST36, the mounting position of the component P predicted to stand up on the substrate 8 is determined as follows: After correcting the mounting position, the component P is corrected to a position shifted in the direction in which the electrodes T are arranged from a predetermined mounting position (target mounting position read from the storage device 25) on the substrate 8 in advance. (Step ST37), the component P is mounted at the corrected mounting position (step ST38). As a result, the component P predicted to stand up is mounted with being shifted in the direction in which the electrodes T are arranged from a predetermined mounting position on the substrate 8 that is predetermined for the component P (FIG. 9B). .

  As described above, when the mounting position of the component P predicted to stand up on the substrate 8 is shifted from the specified mounting position in the direction in which the electrodes T are arranged, The balance state of the force (surface tension or adhesive force) acting on the component P between the solder S on the land 8a located in the front in the traveling direction and the solder S on the land 8a located in the rear in the traveling direction. Since it can be changed in a stable direction (a direction in which chip standing does not occur), chip standing is eliminated.

  Here, whether the mounting position of the component P on the substrate 8 is shifted in the same direction as the traveling direction of the substrate 8 in the reflow furnace 6 or in the direction opposite to the traveling direction depends on the shape of the land 8a. Since it varies depending on various factors such as the amount and area of the solder S applied on the land 8a, the shape of the component P, the position of the center of gravity, etc., it cannot be determined unconditionally. Since it can be said that there is a tendency to prevent chip standing when shifted in the opposite direction, the direction in which the component P is shifted is usually the direction opposite to the traveling direction of the substrate 8 in the reflow furnace 6 (FIG. 9 ( b) the direction of arrow B shown in the figure). As a result of shifting the mounting position of the component P in the direction opposite to the traveling direction of the substrate 8 in the reflow furnace 6, conversely, the degree of chip standing may increase, but in this case, the component P Since the mounting position of the substrate 8 may be shifted in the same direction as the traveling direction of the substrate 8 in the reflow furnace 6 (the direction opposite to the direction in which the arrow B shown in FIG. 9B faces), at most two trials Thus, it is possible to prevent the chip standing of the same component P mounted on the same location of the same substrate 8.

  On the other hand, when it is determined in step ST36 that there is nothing predicted to stand up, the target mounting position read from the storage device 25 is set at a predetermined position on the substrate 8 for the component P. (According to the data) (step ST38). When the component P sucked by the suction nozzle 19 is mounted on the substrate 8, the positional deviation of the substrate 8 obtained by the image recognition of the substrate camera 21 and the suction nozzle 19 obtained by the image recognition of the component camera 22 are detected. The suction deviation of the component P is corrected.

  As described above, the component mounting method according to the present embodiment has both ends when mounted on a predetermined position (target mounting position) on the substrate 8 among the components P to be mounted on the substrate 8. The direction in which the electrodes T are aligned is coincident with the traveling direction of the substrate 8 in the reflow furnace 6 and the chip is expected to stand when the solder S is heated and melted in the reflow furnace 6. In this case, the mounting is performed by shifting the electrode T from the specified position on the substrate 8 in the direction in which the electrodes T are arranged. The balance state of the surface tension and the adhesive force can be changed in a stable direction (a direction in which the chip does not stand), and the occurrence of the chip standing can be prevented very easily.

  Provided is a component mounting method capable of preventing occurrence of chip standing by a simple method.

Schematic configuration diagram of a component mounting line in an embodiment of the present invention (A) (b) (c) The figure explaining the joining process of the board | substrate and electronic component in one embodiment of this invention The flowchart which shows the flow of the component mounting which the component mounting line in one embodiment of this invention performs (A) The figure which shows the state in which the component was normally mounted in the component mounting line in one embodiment of this invention (b) The state in which the component stood up in the component mounting line in one embodiment of this invention is shown Figure The flowchart which shows the flow of the component mounting process which the component mounting machine in one embodiment of this invention performs The top view of the component mounting machine in one embodiment of this invention The enlarged front view of the transfer head of the component mounting machine in one embodiment of this invention The block diagram which shows the control system of the component mounting machine in one embodiment of this invention (A) (b) The board | substrate which demonstrates how to shift the mounting position of the components in the component mounting process which the component mounting machine in one embodiment of this invention performs, and the top view of components

Explanation of symbols

6 Reflow furnace 8 Substrate P Component T Electrode S Solder

Claims (1)

After components with electrodes at both ends are mounted on a substrate on which solder has been applied in advance by a component mounting machine , the substrate is sent in a certain direction and passed through a reflow furnace, thereby heating and cooling the solder on the substrate A component mounting method for mounting a component on a board,
Among the components to be mounted on the board, when the electrodes are mounted on the board, the direction in which the electrodes on both ends are aligned with the direction in which the board moves in the reflow furnace, and the solder is heated in the reflow furnace. What is expected to stand when the chip is melted is to be mounted by a component mounting machine by shifting it in the direction in which the electrodes are arranged from a predetermined mounting position on the substrate that is predetermined for the component ,
The board that passed through the reflow furnace was inspected by a soldering visual inspection machine, and the parts where the direction of the electrodes aligned with the direction of travel of the board in the reflow furnace had chipped after passing through the reflow furnace. If the information to the effect is sent from the soldering appearance inspection device to the component mounting machine, then if the same component is mounted on the same location on the same board and passed through the reflow furnace, the component is A component mounting method characterized by predicting that a chip stands .

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