JP7520463B2 - Board production system and board production method - Google Patents

Description

The present invention relates to a technology for producing a board on which components are mounted by placing components on solder printed at component mounting locations on the board.

Conventionally, a board with components mounted thereon is produced by carrying out a series of processes, such as printing solder on the component mounting location on the board, placing the components on the solder printed on the component mounting location, and melting the solder by heating. In such board production, it is required that the components are accurately mounted on the component mounting location by the solder. However, due to the influence of the positioning accuracy between the mask used in printing the solder and the board, a positional deviation may occur between the solder and the component mounting location. In such a case, as described in Patent Document 1, by adjusting the placement position of the component relative to the solder, the component can be moved toward the component mounting location by the self-alignment effect that accompanies the melting of the solder.

JP 2007-110170 A

However, the magnitude of the self-alignment effect is affected by factors such as the external shape and weight of the component, and the degree of misalignment between the component mounting location and the solder. As a result, it is not possible to predict how the component will move due to the self-alignment effect, and it is difficult to determine in which position the component should be placed relative to solder that has been printed misaligned from the component mounting location. As a result, there are cases where the component cannot be mounted accurately in the component mounting location.

The present invention was made in consideration of the above problems, and aims to provide a technology that enables components to be accurately mounted at component mounting locations on a board, regardless of the magnitude of the self-alignment effect.

The board production system according to the present invention includes a component mounter that places components on solder printed on a component mounting location on a board, and a control device that controls the position at which the component mounter places the component on the solder printed on the component mounting location based on performance data acquired through a printing process that prints solder on the component mounting location, a mounting process that places the component on the solder printed by the printing process, and a reflow process that melts the solder by heating the board on which the component is placed by the mounting process. The performance data shows the measurement results of the printing position, which is the position of the solder printed on a board in the printing process relative to the component mounting location, measured before the reflow process, and the mounting position, which is the position of the component placed on the board in the mounting process relative to the component mounting location, and the inspection results of a post-reflow inspection that determines whether the component is properly mounted on the component mounting location of the board after the reflow process.

The board production method according to the present invention includes a process of acquiring performance data through a printing process of printing solder on component mounting locations on a board, a mounting process of placing components on the solder printed by the printing process, and a reflow process of melting the solder by heating the board on which the components have been placed by the mounting process, and a process of controlling the position at which a component mounter places a component on the solder printed on the component mounting location based on the performance data. The performance data shows the corresponding measurement results of the printing position, which is the position of the solder printed on a board in the printing process relative to the component mounting location, and the placement position, which is the position of the component placed on the board in the mounting process relative to the component mounting location, measured before the reflow process, and the inspection results of a post-reflow inspection that determines whether the component is properly mounted on the component mounting location of the board after the reflow process.

In the present invention (board production system, board production method) configured in this way, the placement of components on the component mounting location by the component mounter is controlled based on the performance data acquired through the printing process, the mounting process, and the reflow process. This performance data shows the corresponding measurement results of the printing position, which is the position of the solder printed on a board in the printing process relative to the component mounting location, and the placement position, which is the position of the component placed on the board in the mounting process relative to the component mounting location, measured before the reflow process, and the inspection result of the post-reflow inspection that determines whether the component mounting on the component mounting location of the board is good or bad after the reflow process. In other words, the performance data shows the corresponding printing position of the solder and the placement position of the component, and the quality of the component mounting. By controlling the placement position of the component relative to the solder based on such performance data, the component can be placed in an appropriate position that takes into account the magnitude of the self-alignment effect. As a result, it is possible to accurately mount the component on the component mounting location of the board regardless of the difference in the magnitude of the self-alignment effect.

The board production system may also be configured so that a post-printing inspection is performed on boards on which printing has been performed but mounting has not been performed to determine whether the printing position is good or not, and the control device determines from the performance data a print tolerance range, which is the allowable range of the printing position required for the component mounting to be determined to be good at a predetermined first rate or higher in the post-reflow inspection, and the post-printing inspection determines whether the printing position is good or not based on the results of comparing the printing position with the print tolerance range. In such a configuration, the quality of the printing position can be determined based on an appropriate print tolerance range that takes into account the performance data.

The board production system may further include a solder printer that aligns a mask having openings corresponding to the component mounting locations with the board and prints solder on the component mounting locations through the openings, and multiple component mounting locations are provided on the board. The control device controls the alignment of the mask and board by the solder printer based on the positional relationship between the mask and board calculated by applying the least squares method to the results of determining the printing position for each of the multiple component mounting locations, and the least squares method may be configured to assign a larger weighting coefficient to component mounting locations with narrower printing tolerances. With this configuration, the mask openings can be appropriately aligned with each of the multiple component mounting locations on the board.

The control device may also be configured to determine the print tolerance range based on the results of learning the relationship between the measurement results and the inspection results through machine learning using performance data as teaching data. In this configuration, an appropriate print tolerance range can be determined based on performance data.

The board production system may also be configured so that the first ratio is 100%. In such a configuration, the quality of the printing position can be determined based on an appropriate printing tolerance range.

The board production system may also be configured so that a post-mounting inspection is performed on boards on which mounting has been performed but reflow processing has not been performed to determine whether the placement position is good or not, and the control device determines, from performance data for multiple cases with different printing positions, a placement tolerance range, which is the permissible range of the placement position required for the post-reflow inspection to determine that the component mounting is good at or above a predetermined second rate, and in the post-mounting inspection, the placement position is determined to be good or not based on the results of comparing the placement tolerance range corresponding to the printing position of the target component mounting location with the placement position of the target component mounting location. In such a configuration, the placement position can be determined to be good or not based on an appropriate placement tolerance range that takes into account the performance data.

The substrate production system may also be configured so that the control device determines the placement tolerance range based on the results of learning the relationship between the measurement results and the inspection results through machine learning using performance data as teaching data. In such a configuration, an appropriate placement tolerance range can be determined based on performance data.

The board production system may also be configured so that the second ratio is 100%. In such a configuration, the quality of the placement position can be determined based on an appropriate printing tolerance range.

The control device may also configure the board production system so that it learns the relationship between the results of the post-reflow inspection and correlation factors that are correlated with the results of the post-reflow inspection, including at least the weight of the components, by machine learning using actual data as teaching data, and stores the learned relationship. In such a configuration, the influence of the stored correlation factors can be referenced and used to help with board production.

As described above, according to the present invention, it is possible to accurately mount components at the component mounting locations on the board, regardless of the magnitude of the self-alignment effect.

1 is a block diagram showing an example of a board production system according to the present invention. FIG. 2 is a front view showing a schematic diagram of a solder printer; FIG. 2 is a plan view showing a component mounter. 11A to 11C are plan views each showing a schematic diagram of a first to third mounting examples showing changes in the state of a board after a printing process, a mounting process, and a reflow process, and results of a board inspection. 11A to 11C are plan views each showing a schematic diagram of fourth to sixth mounting examples showing changes in the state of a board after a printing process, a mounting process, and a reflow process, and results of a board inspection. FIG. 4 is a plan view showing a schematic view of solder printing positions and component placement positions. FIG. 13 is a diagram showing an example of performance data in the form of a table. FIG. 4 is a diagram showing the content of an analysis performed on performance data. 5 is a flowchart showing a first example of an operation executed under the control of a server computer of the board production system. 10 is a flowchart showing a second example of an operation executed under the control of the server computer of the board production system.

Figure 1 is a block diagram showing an example of a board production system according to the present invention. The board production system 1 includes a solder printer 2, a print inspection machine 3, a component mounter 4, a mounting inspection machine 5, a reflow oven 6, a board inspection machine 7, and a server computer 9 that controls these devices 2 to 7. The solder printer 2 prints solder on board B (Figure 2), and the print inspection machine 3 inspects the state of the solder printed by the solder printer 2. The component mounter 4 places components on the solder of board B that has been inspected for its solder printing state by the print inspection machine 3, and the mounting inspection machine 5 inspects the mounting state of the components by the component mounter 4. The reflow oven 6 heats board B that has been inspected for its component mounting state by the mounting inspection machine 5 to melt the solder printed on board B, and the board inspection machine 7 inspects the mounting state of the components on board B that has been heated by the reflow oven 6. In this way, the board production system 1 produces boards B with components mounted (board production).

The transport of boards B to devices 2 to 7 can be performed by a transport robot such as a conveyor or an AGV (Automated Guided Vehicle), or by an operator. Boards B that are determined to be defective in the inspection by the print inspection machine 3 are not transported to the component mounter 4, and boards B that are determined to be defective in the inspection by the mounting inspection machine 5 are not transported to the mounting inspection machine 5.

The server computer 9 manages and controls board production in the board production system 1. This server computer 9 has a memory unit 91 composed of a HDD (Hard Disk Drive) or the like, and a learning unit 92 composed of a processor or the like having a calculation function. The memory unit 91 and the learning unit 92 execute machine learning, which will be described later.

Figure 2 is a front view showing a solder printer. In Figure 2 and the following figures, XYZ orthogonal coordinate axes are appropriately shown, with the Z direction being the vertical direction and the X and Y directions being the horizontal directions. The solder printer 2 prints solder on the lands of the board B using a mask M through which pattern holes corresponding to the lands of the board B penetrate. This solder printer 2 includes a mask holding unit 21 that holds the mask M, a board holding unit 23 arranged below the mask M, and a squeegee unit 29 arranged above the mask M. The solder printer 2 then prints the solder supplied to the top surface of the mask M on the top surface of the board B through the pattern holes of the mask M by sliding the squeegee 291 of the squeegee unit 29 in the X direction on the top surface of the mask M while facing the board B from below using the board holding unit 23 (printing process).

The substrate holding unit 23 is disposed below the mask M held by the mask holding unit 2, and aligns the position of the substrate B with respect to the mask M. The substrate holding unit 23 has a pair of conveyors 24 that transport the substrate B, a substrate holding section 25 that holds the substrate B received from the conveyors 24, and a flat movable table 26 that supports the conveyors 24 and the substrate holding section 25.

The pair of conveyors 24 are arranged parallel to each other in the Y direction with a gap in the X direction, and each conveyor supports both ends of the substrate B in the X direction from below with its upper surface. Each conveyor 24 transports the substrate B in the Y direction, and carries the substrate B into or out of the printing device 1.

The substrate holder 25 has a flat lift table 251 and a slide support 252 that can slide in the Z direction relative to the movable table 26, and the lift table 251 is supported on the upper end of the slide support 252. In addition, a plurality of backup pins 253 erected in the Z direction are arranged at intervals in the X and Y directions on the upper surface of the lift table 251. Then, as the slide support 252 rises and falls, the backup pins 253 rise and fall together with the lift table 251. For example, when the conveyor 24 carries in the substrate B, the upper end of each backup pin 253 is positioned below the upper surface of the conveyor 24. Then, when the conveyor 24 carries in the substrate B directly above the backup pin 253, the backup pin 253 rises and the upper end of the backup pin 253 protrudes upward from the upper surface of the conveyor 24. As a result, the substrate B is transferred from the upper surface of the conveyor 24 to the upper ends of each backup pin 253.

The substrate holder 25 also has a pair of clamp plates 254 spaced apart in the X direction above the pair of conveyors 24. The upper surface of each clamp plate 254 is a plane parallel to the X and Y directions and is located at the same height. At least one of these clamp plates 254 is movable in the X direction.

Then, the substrate B on the backup pin 253 rises up to between the pair of clamp plates 254, and the movable clamp plates 254 move in the X direction, narrowing the gap between the clamp plates 254 and clamping the substrate B from the X direction (horizontal direction) by the clamp plates 254.

Furthermore, the substrate holding unit 23 has a table driving mechanism 27 that drives the movable table 26. This table driving mechanism 27 has an X-axis table 271, a Y-axis table 272 attached to the upper surface of the X-axis table 271, an R-axis table 273 attached to the upper surface of the Y-axis table 272, and a ball screw 274 that raises and lowers the movable table 26 relative to the R-axis table 273. This table driving mechanism 27 drives the X-axis table 271 in the X direction, drives the Y-axis table 272 in the Y direction, drives the R-axis table 273 in the R direction (a rotation direction centered on an axis parallel to the Z direction), and drives the movable table 26 in the Z direction by rotating the ball screw 274. In other words, the table driving mechanism 27 can drive the conveyor 24 and substrate holding unit 25 arranged on the movable table 26 in the X, Y, Z, and R directions. For example, when positioning the loaded substrate B relative to the mask M, the table drive mechanism 27 adjusts the position of the substrate B clamped to the clamp plate 254 in the X, Y, and R directions while raising it in the Z direction. This causes the upper surfaces of the clamp plate 254 and the substrate B to come into contact with the lower surface of the mask M.

The squeegee unit 29 adjusts the rotation angle of the squeegee 291 to bring the squeegee 291 into contact with the upper surface of the mask M at a predetermined angle (attack angle) and presses the squeegee 291 against the mask M with a predetermined pressure (printing pressure). From this state, the squeegee unit 29 moves the squeegee 291 in the X direction at a predetermined speed (squeegee speed), printing solder onto the lands of the substrate B through the pattern holes in the mask M.

Figure 3 is a plan view showing a component mounter. As shown in Figure 3, the component mounter 4 has a pair of conveyors 41 arranged in parallel in the Y direction. The component mounter 4 mounts components P on board B that has been transported by the conveyors 41 from the upstream side in the Y direction (board transport direction) to a mounting processing position (the position of board B in Figure 3), and transports the board B (component-mounted board B) with the mounting of components P completed from the mounting processing position to the downstream side in the Y direction by the conveyors 41.

In this component mounter 4, a pair of X-axis rails 421 parallel to the X direction, an X-axis ball screw 422 parallel to the X direction, and an X-axis motor 423 (servo motor) that rotates and drives the X-axis ball screw 422 are provided, and a Y-axis rail 424 parallel to the Y direction is supported by the pair of X-axis rails 421 so as to be movable in the X direction and is fixed to the nut of the X-axis ball screw 422. A Y-axis ball screw 425 parallel to the Y direction and a Y-axis motor 426 (servo motor) that rotates and drives the Y-axis ball screw 425 are attached to the Y-axis rail 424, and the head unit 43 is fixed to the nut of the Y-axis ball screw 425 while being supported by the Y-axis rail 424 so as to be movable in the Y direction. Therefore, the X-axis motor 423 rotates the X-axis ball screw 422 to move the head unit 43 in the X direction, and the Y-axis motor 426 rotates the Y-axis ball screw 425 to move the head unit 43 in the Y direction.

The head unit 43 has a so-called rotary type mounting head 431. In other words, the mounting head 431 has multiple (eight) nozzles 432 arranged at equal angular intervals in a circular shape centered on a rotation axis, and the multiple nozzles 432 can rotate around the rotation axis.

As shown in FIG. 3, two component supply units 44 are arranged in the X direction on each side of the pair of conveyors 41 in the Y direction. A plurality of tape feeders 441 are arranged in the Y direction and detachably attached to each component supply unit 44. The tape feeders 441 extend in the X direction and have a component supply point 442 at the tip of the conveyor 41 side in the X direction. A component supply reel around which a tape is wound containing small pieces of components P such as integrated circuits, transistors, and capacitors at predetermined intervals is arranged for each tape feeder 441, and the tape pulled out from the component supply reel is loaded into the tape feeder 441. The tape feeder 441 intermittently feeds the tape in the X direction toward the conveyor 41 side. As a result, the components P in the tape are fed in the X direction (feed direction) and supplied in order to the component supply points 442 of the tape feeder 441.

Then, the mounting head 431 picks up and places the component P using each nozzle 432. Specifically, the mounting head 431 moves above the tape feeder 441 and brings the nozzle 432 into contact with the component P supplied to the component supply point 442 by the tape feeder 441. The mounting head 431 then generates a predetermined negative pressure in the mounting head 431, causing the nozzle 432 to pick up the component P. While holding the component P in this way, the mounting head 431 moves above the board B at the mounting processing position at a predetermined transfer speed and places the component P on the board B. In this way, the mounting process of picking up the component P and placing it on the board B is executed by the component mounter 4.

In this way, in the board production system 1, a board B on which components P are mounted is produced through printing of solder by the solder printer 2 (printing process), mounting of components P by the component mounter 4 (mounting process), and melting of the solder by the reflow furnace 6 (reflow process). The quality of component mounting on the board B thus produced is inspected by the board inspection machine 7 (board inspection). Next, the series of operations performed on the board B in the board production system 1 will be described.

Figure 4 is a plan view showing the change in state of the board after printing, mounting and reflow processing, and the results of board inspection in the first to third mounting examples. The "immediately after printing" column in Figure 4 shows the state of board B after printing by the solder printer 2 has been performed but mounting by the component mounter 4 has not yet been performed. As shown in the "immediately after printing" column, the solder printer 2 prints solder S on the land Bl of board B. In the first and second mounting examples, the solder S is printed in the center of the land Bl, and the printing position of the solder S coincides with the land Bl. On the other hand, in the third mounting example, the printing position of the solder S is shifted to the right of the land Bl, and the solder S extends beyond the land Bl to the right.

In the "immediately after mounting" column in FIG. 4, the state of the board B is shown after the mounting process by the component mounter 4 has been performed but the reflow process by the reflow furnace 6 has not yet been performed. As shown in the "immediately after mounting" column, the component mounter 4 places a component P on the solder S printed on the land Bl of the board B. The end of the component P is provided with a terminal of the component P, and the end of the component P placed on the solder S is electrically connected to the land Bl via the solder S. In the first mounting example, the placement position of the component P coincides with the printing position of the solder S, and the end of the component P is located in the center of the solder S. On the other hand, in the second mounting example, the placement position of the component P is shifted to the right with respect to the printing position of the solder S, and the component P protrudes to the right from the solder S. Also, in the third mounting example, the placement position of the component P coincides with the land Bl, but is shifted to the left with respect to the printing position of the solder S, and the component P protrudes to the left from the solder S.

In this way, in the first implementation example, the printing position of the solder S and the placement position of the component P coincide with the land Bl. In the second implementation example, the printing position of the solder S coincides with the land Bl, while the placement position of the component P is shifted to the right relative to the printing positions of the land Bl and the solder S. In the third implementation example, the placement position of the component P coincides with the land Bl, while the printing position of the solder S is shifted to the right relative to the placement positions of the land Bl and the component P.

The "immediately after reflow" column in FIG. 4 shows the state of the board B after reflow processing in the reflow furnace 6 has been performed. As shown in the "immediately after reflow" column, the solder S melts and spreads due to the heat of the reflow. At this time, in all of the first to third mounting examples, the solder S spreads over the entire land Bl without protruding from the land Bl, and the end of the component P is also located in the center of the land Bl. As a result, the results of the board inspection by the board inspection machine 7 are good (OK) for each mounting example. In other words, in the second and third mounting examples, although the placement position of the component P or the printing position of the solder S is misaligned with respect to the land Bl, the solder S and the component P are attracted to the land Bl due to the self-alignment effect that accompanies the melting of the solder S.

The results in Figure 4 show that even if the printing position of the solder S is misaligned from the land B1, the self-alignment effect associated with the reflow process can result in good results in the board inspection. Therefore, the relationship between the misalignment of the printing position of the solder S relative to the land B1 and the placement position of the component P will be explained using Figure 5.

Figure 5 is a plan view showing the change in state of the board after printing, mounting and reflow processing, and the results of board inspection for the fourth to sixth mounting examples. The contents indicated by "immediately after printing", "immediately after mounting" and "immediately after reflow" in Figure 5 are the same as those in Figure 4. As shown in the "immediately after printing" column in Figure 5, in each of the fourth to sixth mounting examples, the printing position of solder S is shifted to the right of land Bl by the same amount, and solder S similarly protrudes to the right from land Bl.

As shown in the "immediately after mounting" column in FIG. 5, in the fourth mounting example, the placement position of the component P coincides with the land Bl, but is shifted to the left with respect to the printed position of the solder S, and the component P protrudes to the left from the solder S. In the fifth mounting example, the placement position of the component P is shifted to the right with respect to the land Bl, but is shifted to the left with respect to the solder S, and the component P protrudes to the right from the land Bl, but also protrudes to the left from the solder S. In the sixth mounting example, the placement position of the component P coincides with the printed position of the solder S, but is shifted to the right with respect to the land Bl, and the component P protrudes to the right from the land Bl. In this way, FIG. 5 shows the fourth to sixth mounting examples in which the printed position of the solder S is uniformly shifted to the right with respect to the land Bl, while the placement position of the component P is different with respect to the printed position of the solder S.

As shown in the "immediately after reflow" column in FIG. 5, in the fourth and sixth mounting examples, the solder S and the component P are shifted to the right and protrude from the land Bl, and the result of the board inspection is bad (NG). In other words, the fourth mounting example suggests that if the component P is significantly shifted from the solder S, the result of the board inspection will be bad, and the sixth mounting example suggests that if the component P is significantly shifted from the land Bl, the result of the board inspection will be bad. On the other hand, in the fifth mounting example, the solder S does not protrude from the land Bl but spreads over the entire land Bl, and the end of the component P is also located in the center of the land Bl. This suggests that even if the printing position of the solder S is shifted from the land Bl, the self-alignment effect can be used to obtain good board inspection results by keeping the distance between the printing positions of the land Bl and the solder S and the placement position of the component P within a specified range.

Therefore, in board production in the board production system 1, the server computer 9 measures the printing position of the solder S relative to the land Bl in a printing inspection by the print inspection machine 3, and measures the placement position of the component P relative to the land Bl in a mounting inspection by the mounting inspection machine 5. The server computer 9 then associates the printing position and placement position with the results of the board inspection by the board inspection machine 7, and collects and stores them as performance data.

Figure 6 is a plan view showing a schematic representation of the solder printing position and the component placement position, and Figure 7 is a diagram showing an example of performance data in the form of a table. As shown in Figure 6, the position of land Bl can be represented by the center (geometric center of gravity) of land Bl in a planar view (as viewed from the Z direction), the position of solder S can be represented by the center (geometric center of gravity) of solder S in a planar view, and the position of component P can be represented by the center (geometric center of gravity) of component P in a planar view. The print inspection machine 3 then measures the printing position Ls of solder S relative to the position Ll of land Bl, and the mounting inspection machine 5 measures the placement position Lp of component P relative to land Bl.

As shown in FIG. 7, the printing position Ls and placement position Lp measured in this manner are stored as performance data D in the memory unit 91 of the server computer 9 in association with the board inspection results (OK/NG) of the board inspection machine 7. This performance data D is obtained for each of the multiple lands Bl provided on the board B and stored in association with the land Bl. Note that FIG. 7 illustrates multiple performance data D(1), D(2), ..., D(8), ... obtained for one land Bl. The server computer 9 then analyzes the multiple performance data D thus accumulated to obtain the relationship that holds between the printing position Ls, placement position Lp, and the board inspection results.

Figure 8 is a diagram showing the contents of the analysis performed on the performance data. In each of the columns "small", "medium" and "large" in Figure 8, a distribution diagram of good products is shown, which is obtained by plotting the performance data D on a graph with the placement position Lp on the horizontal axis and the good product rate on the vertical axis. In particular, the good product distribution rates in each of the columns "small", "medium" and "large" are shown corresponding to the case where the printing misalignment of the solder S (i.e., the size of the printing position Ls) is different from small, medium and large. Here, each class of "small", "medium" and "large" indicating the degree of solder misalignment has a width, and for example, a solder misalignment whose magnitude is equal to or greater than zero and less than f1 (>0) belongs to the "small" class, a solder misalignment whose magnitude is equal to or greater than f1 and less than f2 (>f2) belongs to the "medium" class, and a solder misalignment whose magnitude is equal to or greater than f2 belongs to the "large" class. A set of multiple (three in this example) good product distribution rates corresponding to different solder misalignment magnitudes is obtained for each land Bl. Note that the number of classes that divide the magnitude of solder misalignment is not limited to three as in this example, and can be four or more.

When the printing misalignment is "small", when the placement position Lp of component P is in the range from position lp1 to position lp2, the pass rate of the board inspection results (the proportion of inspection results that are OK relative to the number of inspections) will be 100%, and the range from position lp1 to position lp2 will be the appropriate placement range Aps for placing component P. When the printing misalignment is "medium", when the placement position Lp of component P is in the range from position lp3 to position lp4, the pass rate of the board inspection results will be 100%, and the range from position lp3 to position lp4 will be the appropriate placement range Apm for placing component P. On the other hand, when the printing misalignment is "large", there is no range where the pass rate is 100%, i.e., no appropriate placement range Ap.

The median of the appropriate placement range Apm (= (lp3 + lp4) / 2) when the printing misalignment is "medium" is farther from the origin (i.e., the position Ll of land Bl) than the median of the appropriate placement range Aps (= (lp1 + lp2) / 2) when the printing misalignment is "small". Also, the appropriate placement range Apm when the printing misalignment is "medium" is narrower than the appropriate placement range Aps when the printing misalignment is "small". Therefore, it can be seen that the farther the printing position Ls is from land Bl, the farther the median of the appropriate placement range Ap is from land Bl and the narrower the appropriate placement range Ap becomes.

Figure 9 is a flow chart showing a first example of the operation executed under the control of the server computer of the board production system. As shown in Figure 9, the server computer 9 collects, stores, and analyzes the performance data D as described above in parallel with the production of the board B on which components have been mounted.

In other words, when board production begins, board B is carried into the solder printer 2 located at the most upstream position of the board production system 1, and a printing process is performed on board B (step S102). In this printing process, the solder printer 2 aligns the mask M with the board B by adjusting the position of the board B using the table drive mechanism 27 based on the results of capturing an image of the fiducial mark attached to the board B using a camera. This aligns the position of the land Bl of the board B with the position of the pattern hole of the mask M. Then, the solder printer 2 prints solder S onto the land Bl of the board B through the pattern hole of the mask M by sliding the top surface of the mask M with the squeegee 291.

The board B on which the solder S has been printed by the solder printer 2 is transported from the solder printer 2 to the print inspection machine 3. The print inspection machine 3 then performs a print inspection on the board B that has been transported thereto (step S103). In the print inspection, the print inspection machine 3 measures the position of the solder S relative to the land Bl, i.e., the print position Ls, based on the result of capturing an image of the solder S printed on the land Bl by a camera. In this way, the print position Ls of the solder S measured for each of the multiple lands Bl is transmitted from the print inspection machine 3 to the memory unit 91 of the server computer 9 and stored in the memory unit 91.

Furthermore, in the printing inspection, the quality of the measured printing position Ls is judged. Specifically, if the printing position Ls is within a predetermined range, the printing position Ls is judged to be good, whereas if the printing position Ls is outside the predetermined range, the printing position Ls is judged to be bad. Then, a board B in which the printing positions Ls of all lands Bl are judged to be good is transported from the printing inspection machine 3 to the component mounter 4, whereas a board B having lands Bl in which the printing position Ls is judged to be bad is not transported from the printing inspection machine 3 to the component mounter 4.

The component mounter 4 performs mounting processing on the board B that has been brought in (step S104). In the mounting processing, the component mounter 4 places the component P on the solder S printed on the land Bl based on the results of capturing images of the fiducial marks on the board B and the component P picked up by the mounting head 431 using a camera.

The board B on which the component P has been placed by the component mounter 4 is transported from the component mounter 4 to the mounting inspection machine 5. The mounting inspection machine 5 then performs a mounting inspection on the board B that has been transported therefrom (step S105). In the mounting inspection, the mounting inspection machine 5 measures the position of the component P relative to the land Bl, i.e., the placement position Lp, based on the result of capturing an image of the component P placed on the solder S printed on the land Bl by a camera. In this way, the placement position Lp of the component P measured for each of the multiple lands Bl is transmitted from the mounting inspection machine 5 to the memory unit 91 of the server computer 9 and stored in the memory unit 91.

Furthermore, in the mounting inspection, the quality of the measured placement position Lp is judged. Specifically, if the placement position Lp is within a predetermined range, the print position Ls is judged to be good, whereas if the placement position Lp is outside the predetermined range, the placement position Lp is judged to be bad. Then, a board B for which the placement positions Lp for all lands Bl are judged to be good is transported from the mounting inspection machine 5 to the reflow furnace 6, whereas a board B having lands Bl for which the placement positions Lp are judged to be bad is not transported from the mounting inspection machine 5 to the reflow furnace 6.

The reflow furnace 6 performs a reflow process on the board B that has been brought in (step S106). In the reflow process, the reflow furnace 6 heats the board B according to a predetermined temperature profile, thereby melting the solder S printed on the lands Bl of the board B.

The board B heated in the reflow furnace 6 is transported from the reflow furnace 6 to the board inspection machine 7. The board inspection machine 7 then performs a board inspection on the board B that has been transported therein (step S107). In the board inspection, the board inspection machine 7 judges whether the mounting state of the component P on the land Bl is good or bad (OK/NG) based on the position of the component P relative to the land Bl and the position and shape of the solder S that joins the land Bl and the component P. In this way, the board inspection machine 7 transmits the good or bad mounting state of the component P determined for each of the multiple lands Bl (board inspection result) to the memory unit 91 of the server computer 9 and stores it in the memory unit 91. In this way, the memory unit 91 acquires and stores performance data D for each of the multiple lands Bl.

The server computer 9 uses the learning unit 92 to analyze the performance data D stored in the memory unit 91, and calculates the relationship between the printing position Ls and the appropriate placement range Ap illustrated in FIG. 8 through machine learning. Specifically, the learning unit 92 prepares multiple classes indicating different printing ranges (corresponding to the printing misalignment "small", "medium", and "large" in FIG. 8), and classifies the performance data D into classes that include the printing position Ls. The learning unit 92 then calculates, through machine learning, the appropriate placement range Ap for which the non-defective product rate is equal to or greater than a predetermined rate (100% in this example).

Also, as the example in Figure 8 suggests, if the printing position Ls deviates from the specified appropriate printing range As, there will be no appropriate placement range Ap with a 100% yield rate (printing misalignment "large" in Figure 8). Therefore, the learning unit 92 calculates the appropriate printing range As in which the appropriate placement range Ap exists by machine learning. In other words, if the printing position Ls is within the appropriate printing range As, the appropriate placement range Ap exists, and if the printing position Ls is outside the appropriate printing range As, the appropriate placement range Ap does not exist. The appropriate placement range Ap and appropriate printing range As are found for each of the multiple lands Bl of the substrate B.

Furthermore, the server computer 9 calculates the appropriate position of the substrate B relative to the mask M in the print inspection machine 3. Specifically, the least squares method is applied to the printing positions Ls of the solder S measured for the multiple lands Bl (in other words, the positional deviation between the land Bl and the solder S), thereby calculating the appropriate position of the substrate B relative to the mask M. In particular, the server computer 9 compares the appropriate printing ranges As determined for each of the multiple lands Bl, and performs the least squares method by assigning a larger weighting coefficient to the land Bl with the narrower appropriate printing range As. Such least squares calculations may be performed by the calculation function of the learning unit 92, or may be performed by a processor different from the learning unit 92.

Figure 10 is a flowchart showing a second example of the operations executed under the control of the server computer of the board production system. When a sufficient amount of performance data D is accumulated as a result of execution of the flowchart in Figure 9, the server computer 9 switches the flowchart executed in connection with board production from Figure 9 to Figure 10. The difference between Figure 9 and Figure 10 is that in Figure 10, the analysis results from the learning unit 92 are used for board production, and the operations executed in Figure 9 are also executed in Figure 10. Here, the explanation will focus on the differences from Figure 9, and the contents in common with Figure 9 will be denoted by the corresponding symbols and will not be explained.

In step S102, the solder printer 2 adjusts the position of the substrate B relative to the mask M based on the correct position received from the learning unit 92. As a result, with the substrate B aligned in the correct position relative to the mask M, the solder S is printed on the land Bl of the substrate B through the pattern holes of the mask M.

In step S103, the print inspection machine 3 performs print inspection by comparing the measured print position Ls with the appropriate print range As. Specifically, if the print position Ls is within the appropriate print range As, the print position Ls is determined to be good, and if the print position Ls is outside the appropriate print range As, the print position Ls is determined to be bad.

In step S104, the placement of the component P on the component mounter 4 is controlled based on the printing position Ls measured in the immediately preceding print inspection (step S103). Specifically, the learning unit 92 calculates the appropriate placement range Ap for each land Bl as described above based on the printing position Ls of each land Bl measured in the print inspection in step S103. The learning unit 92 then sets the median of the appropriate placement range Ap as the target position for placing the component P. The target positions thus determined for each of the multiple lands Bl are transmitted from the learning unit 92 to the component mounter 4, and the component mounter 4 places the component P on the solder S printed on the land Bl by transferring the component P toward the target position set for the land Bl.

In step S105, the mounting inspection machine 5 performs a mounting inspection by comparing the measured placement position Lp with the appropriate placement range Ap. Specifically, the learning unit 92 transmits to the component mounter 4 the appropriate placement range Ap of each land Bl calculated based on the printing position Ls of each land Bl measured in the printing inspection in step S103. The component mounter 4 also measures the placement position Lp of the component P placed on the land Bl and determines whether the placement position Lp is within the appropriate placement range Ap for the land Bl. If the placement position Lp is within the appropriate placement range Ap, the placement position Lp is determined to be good, and if the placement position Lp is outside the appropriate placement range Ap, the placement position Lp is determined to be bad.

In the embodiment described above, the placement of the component P on the land Bl (component mounting location) by the component mounter 4 is controlled (step S104) based on the performance data D acquired through the printing process (step S102), the mounting process (step S104), and the reflow process (step 106). This performance data D shows the measurement results of the printing position Ls, which is the position of the solder S printed on one board B relative to the land Bl in the printing process, and the placement position Lp, which is the position of the component P placed on the one board B relative to the land Bl in the mounting process, measured before the reflow process in step S106 (steps S103 and S105), and the result of the board inspection (post-reflow inspection) in step S107, which determines whether the mounting of the component P on the land Bl of the one board B is good or bad after the reflow process. In other words, the performance data D shows the printing position Ls of the solder S and the placement position Lp of the component P in association with the quality of the component mounting. By controlling the placement position Lp of the component P relative to the solder S based on the performance data D, the component P can be placed in an appropriate position that takes into account the magnitude of the self-alignment effect. As a result, it is possible to accurately mount the component P on the land Bl of the board B, regardless of the magnitude of the self-alignment effect.

A printing inspection (post-printing inspection) is also performed on the board B on which the printing process has been performed but the mounting process has not yet been performed, to determine whether the printing position Ls is good or not (step S103). In response to this, the server computer 9 (control device) obtains from the performance data D the appropriate printing range As (printing tolerance range), which is the tolerance range of the printing position Ls required for the mounting of the component P to be determined to be good at 100% (first rate) in the printing inspection. Then, in the printing inspection, the quality of the printing position Ls is determined based on the results of comparing the printing position Ls with the appropriate printing range As. In this configuration, the quality of the printing position Ls can be determined based on the appropriate appropriate printing range As that takes into account the performance data D.

The system also includes a solder printer 2 that aligns a mask M having pattern holes (openings) corresponding to the lands Bl with the substrate B, and prints solder S on the lands Bl through the pattern holes. The server computer 9 controls the alignment of the mask M with the substrate B by the solder printer 2 based on the positional relationship between the mask M and the substrate B calculated by applying the least squares method to the results of determining the printing position Ls for each of the multiple lands Bl on the substrate B. In particular, with this least squares method, a larger weighting coefficient is assigned to a land Bl with a narrower appropriate printing range As. With this configuration, the pattern holes of the mask M can be appropriately aligned with each of the multiple lands Bl on the substrate B.

The server computer 9 also uses the performance data D as teaching data to learn the relationship between the measurement results (printing position Ls, placement position Lp) and the inspection results (OK/NG) by the board inspection machine 7 through machine learning to determine the appropriate printing range As. With this configuration, it is possible to determine the appropriate printing range As based on the performance data D.

In addition, a mounting inspection (post-mounting inspection) is performed on the board B on which mounting processing has been performed but reflow processing has not been performed, to determine whether the placement position Lp is good or not (step S105). The server computer 9 also obtains the appropriate placement range Ap (placement tolerance range), which is the tolerance range of the placement position Lp required for the placement of the component P to be determined to be good at 100% (second rate) or more in the board inspection of step S107, from the performance data D for multiple cases (classes) with different printing positions Ls. Then, in the mounting inspection (step S105), the quality of the placement position Lp is determined based on the result of comparing the appropriate placement range Ap corresponding to the printing position Ls measured for the target land Bl with the placement position Lp measured for the target land Bl. In this configuration, the quality of the placement position Lp can be determined based on the appropriate placement range Ap that is appropriate based on the performance data D.

The server computer 9 also uses the performance data D as teaching data to learn the relationship between the measurement results (printing position Ls, placement position Lp) and the inspection results (OK/NG) by the board inspection machine 7 through machine learning, and determines the appropriate placement range Ap based on the results. With this configuration, it is possible to determine an appropriate placement range Ap based on the performance data D.

As described above, in this embodiment, the board production system 1 corresponds to an example of a "board production system" of the present invention, the solder printing machine 2 corresponds to an example of a "solder printing machine" of the present invention, the component mounting machine 4 corresponds to an example of a "component mounting machine" of the present invention, the server computer 9 corresponds to an example of a "control device" of the present invention, the appropriate placement range Ap corresponds to an example of a "placement tolerance range" of the present invention, the appropriate printing range As corresponds to an example of a "printing tolerance range" of the present invention, the board B corresponds to an example of a "board" of the present invention, the land Bl corresponds to an example of a "component mounting location" of the present invention, the performance data D corresponds to an example of "performance data" of the present invention, the component P corresponds to an example of a "component" of the present invention, the solder S corresponds to an example of a "solder" of the present invention, the printing position Ls corresponds to an example of a "printing position" of the present invention, and the placement position Lp corresponds to an example of a "printing position" of the present invention. corresponds to an example of the "mounting position" of the present invention, the printing position Ls and the mounting position Lp correspond to an example of the "measurement result" of the present invention, the mask M corresponds to an example of the "mask" of the present invention, the board inspection judgment result (OK/NG) corresponds to an example of the "inspection result" of the present invention, the pattern hole corresponds to an example of the "opening" of the present invention, step S102 corresponds to an example of the "printing process" of the present invention, step S103 corresponds to an example of the "post-printing inspection" of the present invention, step S104 corresponds to an example of the "mounting process" of the present invention, step S105 corresponds to an example of the "post-mounting inspection" of the present invention, step S106 corresponds to an example of the "reflow process" of the present invention, step S107 corresponds to an example of the "post-reflow inspection" of the present invention, and 100% corresponds to an example of the "first ratio" and "second ratio" of the present invention.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the yield rate that defines the appropriate placement range Ap or the appropriate printing range As is not limited to 100%, but can be set to any percentage below 100%.

In addition, the specific method for calculating the appropriate placement range Ap or the appropriate printing range As is not limited to machine learning, and these may be calculated using other methods.

In the example of FIG. 6, the printing position Ls and the placement position Lp are calculated for the X direction, but the printing position Ls and the placement position Lp may be calculated for other directions, such as the Y direction or the R direction. In this case, the appropriate placement range Ap and the appropriate printing range As may be calculated for the other direction.

In addition, the performance data D may be configured to include correlation factors other than the printing position Ls and the placement position Lp that are correlated with the board inspection results by the board inspection machine 7. One example of such a correlation factor is the weight of the component P. This makes it possible to refer to the influence of the weight of the component P and use this information to help with board production. Specifically, for example, by handling the weight of the component P in the same way as the printing position Ls described above, the placement position Lp can be controlled based on the appropriate placement range Ap set according to the weight class of the component P.

Furthermore, other correlating factors include the size of the component P, the printing pressure in the printing inspection machine 3, the negative pressure at which the component P is adsorbed in the mounting inspection machine 5, the speed at which the component P is transferred, the type of solder S, or the temperature profile in the reflow furnace 6.

This invention can be applied to the general technology of producing circuit boards with components mounted thereon by placing components on solder printed at component mounting locations on the circuit board.

1... Board production system 2... Solder printer 4... Component mounter 9... Server computer (control device)
Ap...Appropriate placement range (placement tolerance range)
As...Appropriate printing range (printing tolerance range)
B... Board Bl... Land (part mounting location)
D...Actual data P...Component S...Solder Ls...Printing position (measurement result)
Lp: placement position (measurement result)
M: Mask

Claims (8)

a component mounter that places components on solder printed on a component mounting location on a board;
a control device that controls a position at which a component mounter places a component relative to the solder printed at the component mounting location, based on performance data acquired through a printing process that prints solder at the component mounting location, a mounting process that places a component on the solder printed by the printing process, and a reflow process that melts the solder by heating the board on which the component is placed by the mounting process,
the performance data indicates, in association with each other, measurement results obtained by measuring, before the reflow process, a printing position, which is a position of the solder printed on the one board in the printing process relative to the component mounting location, and a mounting position, which is a position of the component mounted on the one board in the mounting process relative to the component mounting location, and an inspection result of a post-reflow inspection that determines, after the reflow process, whether or not the component is mounted on the component mounting location of the one board;
a post-printing inspection is performed on the board on which the printing process has been performed but the mounting process has not been performed, to determine whether the printing position is acceptable or not;
the control device obtains, from the performance data, a non-defective product distribution rate indicating a relationship between the placement position and a non-defective product rate indicated by an inspection result of the post-reflow inspection, and obtains a print allowable range, which is an allowable range of the printing position, required for there to be a proper placement range, which is a range of placement positions where the non-defective product rate is 100%, and
In the post-printing inspection, the board production system judges whether the printing position is acceptable or not based on a result of comparing the printing position with the print tolerance range. a solder printer that aligns a mask having openings corresponding to component mounting locations with a substrate and prints solder on the component mounting locations through the openings ;
a component mounter that places components on the solder printed on the component mounting location on the board;
a control device that controls a position where a component mounter places a component on the solder printed on the component mounting location, based on performance data acquired through a printing process of printing solder on the component mounting location, a mounting process of placing a component on the solder printed by the printing process, and a reflow process of melting the solder by heating the board on which the component is placed by the mounting process; and
Equipped with
the performance data indicates, in association with each other, measurement results obtained by measuring, before the reflow process, a printing position, which is a position of the solder printed on the one board in the printing process relative to the component mounting location, and a mounting position, which is a position of the component mounted on the one board in the mounting process relative to the component mounting location, and an inspection result of a post-reflow inspection that determines, after the reflow process, whether or not the component is mounted on the component mounting location of the one board;
a post-printing inspection is performed on the board on which the printing process has been performed but the mounting process has not been performed, to determine whether the printing position is acceptable or not;
the control device determines, from the performance data, a print tolerance range, which is a tolerance range of the print position required for the mounting of the components to be determined as good at a predetermined first rate or more in the post-reflow inspection;
In the post-printing inspection, the quality of the print position is determined based on a result of comparing the print position with the print tolerance range;
A plurality of the component mounting locations are provided on a substrate,
the control device controls the alignment of the mask and the board by the solder printer based on a positional relationship between the mask and the board calculated by applying a least squares method to a result of determining the printing position for each of the plurality of component mounting locations;
A board production system in which, in the least squares method, a larger weighting coefficient is given to a component mounting location having a narrower printing tolerance range. The board production system according to claim 1 or 2, wherein the control device determines the print tolerance range based on a result of learning a relationship between the measurement results and the inspection results by machine learning using the performance data as teaching data. a component mounter that places components on solder printed on a component mounting location on a board;
a control device that controls a position where a component mounter places a component on the solder printed on the component mounting location, based on performance data acquired through a printing process of printing solder on the component mounting location, a mounting process of placing a component on the solder printed by the printing process, and a reflow process of melting the solder by heating the board on which the component is placed by the mounting process; and
Equipped with
the performance data indicates, in association with each other, measurement results obtained by measuring, before the reflow process, a printing position, which is a position of the solder printed on the one board in the printing process relative to the component mounting location, and a mounting position, which is a position of the component mounted on the one board in the mounting process relative to the component mounting location, and an inspection result of a post-reflow inspection that determines, after the reflow process, whether or not the component is mounted on the component mounting location of the one board;
a post-mounting inspection is performed on the board on which the mounting process has been performed but the reflow process has not been performed, to determine whether the placement position is acceptable or not;
the control device determines, from the performance data, a placement tolerance range, which is a tolerance range of the placement position required for determining that the mounting of the components is good at a predetermined second rate or more in the post-reflow inspection, for a plurality of cases in which the printing positions are different;
In the post-mounting inspection, the board production system determines whether the placement position is acceptable or not based on the results of comparing the placement tolerance range corresponding to the printing position of the target component mounting location with the placement position of the target component mounting location. The board production system according to claim 4 , wherein the control device determines the placement tolerance based on a result of learning a relationship between the measurement result and the inspection result by machine learning using the performance data as teaching data. 6. The board production system according to claim 4, wherein the second ratio is 100%. a component mounter that places components on solder printed on a component mounting location on a board;
a control device that controls a position where a component mounter places a component on the solder printed on the component mounting location, based on performance data acquired through a printing process of printing solder on the component mounting location, a mounting process of placing a component on the solder printed by the printing process, and a reflow process of melting the solder by heating the board on which the component is placed by the mounting process; and
Equipped with
the performance data indicates, in association with each other, measurement results obtained by measuring, before the reflow process, a printing position, which is a position of the solder printed on the one board in the printing process relative to the component mounting location, and a mounting position, which is a position of the component mounted on the one board in the mounting process relative to the component mounting location, and an inspection result of a post-reflow inspection that determines, after the reflow process, whether or not the component is mounted on the component mounting location of the one board;
The control device learns the relationship between the results of the post-reflow inspection and correlation factors, including at least the weight of the components, that are correlated with the results of the post-reflow inspection through machine learning using the performance data as teaching data, and stores the learned relationship. a step of acquiring performance data through a printing process of printing solder on component mounting locations provided on a board, a mounting process of placing components on the solder printed by the printing process, and a reflow process of melting the solder by heating the board on which the components have been placed by the mounting process;
and controlling, based on the performance data, a position at which a component mounter places a component with respect to the solder printed on the component mounting location,
the performance data indicates, in association with each other, measurement results obtained by measuring, before the reflow process, a printing position, which is a position of the solder printed on the one board in the printing process relative to the component mounting location, and a mounting position, which is a position of the component mounted on the one board in the mounting process relative to the component mounting location, and an inspection result of a post-reflow inspection that determines, after the reflow process, whether or not the component is mounted on the component mounting location of the one board ;
a post-printing inspection is performed on the board on which the printing process has been performed but the mounting process has not been performed, to determine whether the printing position is acceptable or not;
A non-defective product distribution rate indicating a relationship between the placement position and a non-defective product rate indicated by the inspection result of the post-reflow inspection is obtained from the performance data, and a print allowable range is obtained, which is an allowable range of the printing position required for there to be an appropriate placement range, which is a range of placement positions where the non-defective product rate is 100%, in the non-defective product distribution rate;
In the post-printing inspection, the print position is compared with the print tolerance range to determine whether the print position is acceptable or not .

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