JP4619896B2 - Reference position determining method, reference position determining apparatus, bonding material printing method and printing apparatus - Google Patents

Description

The present invention relates to a technology for obtaining a reference position relative to circuitry substrate. Such a technique is mainly used for a technique for printing a bonding material for mounting an electronic component on a circuit board and a technique for mounting an electronic component.

  Conventionally, when processing related to mounting electronic components on a circuit board, such as printing solder paste for mounting electronic components on a circuit board, which is a printed wiring board, and mounting electronic components, the circuit board is imaged. Based on the acquired image, a predetermined printing position and mounting position on the circuit board are specified.

For example, in Patent Document 1, the expansion / contraction ratio of the circuit board is calculated by acquiring the positions of two marks provided in advance on the circuit board, and corrected on the circuit board based on the expansion / contraction ratio. A technique for obtaining a mounting position of an electronic component is disclosed. Further, in Patent Document 2, the positions of four or more marks on the circuit board are acquired, the position correction amount is obtained from each of a plurality of combinations in which three marks are selected from these marks, and the positions of all the combinations are obtained. A technique for obtaining a corrected mounting position using an average value of correction amounts is disclosed.
JP-A-63-74530 Japanese Patent Laid-Open No. 11-154799

  By the way, in recent years, flexible circuit boards (for example, FPC (Flexible Printed Circuit Board)) are being used in many cases, and there is a problem that FPC tends to be warped and deformed as compared with conventional so-called rigid boards. is there. For example, when the FPC is warped, the FPC partially floats on the transfer tray that holds and holds the flexible FPC on the upper surface, and the positions of some of the marks are accurate. It may not be obtained. Also, a plurality of FPCs are held on one transport tray, one reference position for all of these FPCs is determined using a plurality of marks, and processing related to mounting of electronic components is performed based on the reference positions. In the case where the mark position is warped in some FPCs where the mark position is detected and rotation or deformation occurs, the reference position cannot be determined accurately, and the position shift with respect to most FPCs. There is a possibility that the processing will be performed in the generated state.

  In recent years, mounting of highly accurate electronic components has also been put into practical use. In this case, the same problem as that of FPC occurs when a reference position for mounting is obtained even on a rigid board.

Accordingly, an object of the present invention is to provide, for solving the above problems, a printing method and printing instrumentation of reference position determination method and the reference position determination device and the bonding material as possible out to determine accurately the reference position with respect to the circuit board Is to provide a place.

  In order to achieve the above object, the present invention is configured as follows.

According to one aspect of the present invention, the circuitry determined Teisu Ru standards location method a reference position of the substrate to obtain the positional relationship of three or more reference position determination for mark provided in the circuitry substrate It is compared with the positional relation of the positional relationship between the pre-Me-determined criteria to identify the warping or reference position determining marks located in the area caused a deformation of the circuit board, a reference position determination specified above When it is determined whether there are two or more reference position determination marks excluding the marks, and when it is determined that there are two or more reference position determination marks excluding the specified reference position determination marks provides standards positioning how to determine the criteria position of the circuit board by using two or more reference positioning mark excluding the marks reference position determination specified above.

According to another aspect of the present invention, in a reference position determination device that determines a reference position of a circuit board, a positional relationship acquisition unit that determines a positional relationship of three or more reference position determination marks provided on the circuit board; A specifying unit for specifying a reference position determining mark located in a warped or deformed region of the circuit board by comparing the positional relationship with a predetermined reference positional relationship; and determining the specified reference position A determination unit that determines whether or not there are two or more reference position determination marks excluding the reference marks, and two or more reference position determination marks that exclude the specified reference position determination marks If it is determined, the reference position with a reference position determining section for determining a reference position of the circuit board by using two or more reference positioning mark excluding the marks reference position determination specified above To provide a constant apparatus.

According to the present invention, the accuracy can and easy flight, it is possible to determine the reference position of the circuit board.

  Specifically, the positions of the three or more reference position determination marks are recognized, and the relative positional relationship of the recognized positions is compared with the reference positional relationship, thereby efficiently positioning the position. It is possible to identify the mark where the deviation has occurred. For example, in the case where the circuit board is an FPC, there may be a situation in which the mark is displaced due to warpage, contraction, lifting, etc. of the FPC, but even in such a case, It is possible to reliably identify the mark where the positional deviation has occurred.

  Before continuing the description of the present invention, the same parts are denoted by the same reference numerals in the accompanying drawings.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a printing apparatus 1 according to an embodiment of the present invention. The printing apparatus 1 in FIG. 1 acquires an image of a transport unit 2 that transports a transport tray 8 that holds a plurality of flexible circuit boards (hereinafter referred to as “FPCs”) 9 on its surface, and an FPC 9. The acquisition unit 3, the FPC 9, a printing unit 4 that prints a solder paste that is a viscous material for mounting electronic components, and a control device 5 that performs overall control of the printing apparatus 1 are provided.

  The transport unit 2 includes a loader 21 that transports the transport tray 8 into the printing apparatus 1, a stage unit 22 that holds the transport tray 8 that has been transported, and a stage unit that moves the stage unit 22 in the Y direction in FIG. The moving device 23 and the unloader 24 for carrying out the FPC 9 after solder paste printing from the printing device 1 are provided. The transfer tray 8 on the stage unit 22 is transferred to the image acquisition unit 3 and the printing unit 4 by the stage unit moving device 23. And move.

  The control device 5 acquires the positions of a plurality of reference position determination marks (hereinafter referred to as “marks”) provided on the FPC 9 by extracting information from the image data input from the image acquisition unit 3. A mark position acquisition unit 51 to perform, a position shift mark specifying unit 52 for specifying a mark in which a position shift occurs among a plurality of marks, and a remaining mark excluding a mark in which a position shift has occurred from a plurality of marks A reference position determination unit 53 for obtaining reference positions for a plurality of FPCs 9 on the tray 8 is provided.

  FIG. 2 is a diagram showing the configuration of the image acquisition unit 3, and shows a state viewed from the (−Y) side toward the (+ Y) direction. The image acquisition unit 3 includes an imaging unit 31 that acquires images of a plurality of FPCs 9 held on the transport tray 8, and an imaging unit moving device 32 that moves the imaging unit 31 in the X direction in FIG. The imaging unit 31 forms an image by the light source 311 that emits illumination light, the optical system 312 that guides the illumination light from the light source 311 to the FPC 9 on the transport tray 8 and the light from the FPC 9 enters, and the optical system 312. The image sensor 313 converts the image of the FPC 9 that has been converted into an electrical signal, and image data of the FPC 9 is output from the image sensor 313 to the control device 5. The image pickup unit moving device 32 includes a ball screw mechanism 322 connected to a motor 321, and the image pickup unit 31 moves in a horizontal direction (X) perpendicular to the moving direction of the stage unit 22 (that is, the Y direction) as the motor 321 rotates. Direction).

  FIG. 3 is a front view showing the configuration of the printing unit 4, and FIG. 4 is a right side view of the printing unit 4 as viewed from the (+ X) side toward the (−X) direction. 3 and 4 show a state in which the stage unit 22 is positioned in the printing unit 4. 3 and 4 are partially shown in cross section for easy understanding of the configuration, and the thickness of the screen 41 is also emphasized.

  The printing unit 4 presses a thin plate-like screen 41 having an opening 411 formed corresponding to a printing pattern, and a solder paste (an example of a bonding material) 81 (see FIG. 4) stacked on the screen 41. A squeegee mechanism 42 (an example of a bonding material supply device) that fills the opening 411 of the screen 41 with the solder paste 81 by moving (that is, squeegeeing) is provided. The screen 41 is fixed in a replaceable manner by a frame 410 provided around the screen 41 being sandwiched between the cylinder 412 and the support portion 413.

  The squeegee mechanism 42 includes a head portion 43 and a head portion moving mechanism 44 that moves the head portion 43 in the Y direction. The head portion moving mechanism 44 has a structure in which a motor that is a driving source is connected to a ball screw mechanism 441. . As shown in FIG. 4, the head portion 43 includes two squeegees (hereinafter referred to as (−), which are arranged to face each other in the Y direction (the moving direction of the head portion 43) with the solder paste 81 stacked on the screen 41 interposed therebetween. Y) side squeegee is referred to as “first squeegee” 431a, and (+ Y) side squeegee is referred to as “second squeegee” 431b). The first squeegee 431a and the second squeegee 431b are formed of urethane rubber. In the squeegee mechanism 42, when the head portion moving mechanism 44 moves the head portion 43 in the Y direction, both the first squeegee 431a and the second squeegee 431b move in the Y direction (that is, integrally).

  The head portion 43 individually moves the first squeegee 431a and the second squeegee 431b in the Z direction (moves up and down individually), and squeegee lifting mechanisms 432a and 432b, and the first squeegee 431a and the second squeegee 431b individually. Are provided with two pressing mechanisms 433a and 433b for pressing the surface of the screen 41 on the (+ Z) side.

  As shown in FIG. 3, the pressing mechanism 433 a is attached to a frame 435 including two guide rods 434 extending in the Z direction, and the guide rod 434 is guided in the Z direction by a bush 436. Below the frame 435 (on the (−Z) side), the frame 437 is attached to the frame 435 so as to be rotatable about a shaft 438 extending in the Y direction, and the rotation range of the frame 437 is limited by the stopper 439. Limited. Similarly, the pressing mechanism 433 b shown in FIG. 4 is attached to another frame 435, and a second squeegee 431 b is attached to the lower side of the frame 435 via another frame 437.

  Further, as shown in FIGS. 3 and 4, the stage unit 22 includes a stage 221 that holds the transfer tray 8 via a suction plate (not shown), and a stage 221 that has an XY plane about an axis that faces the Z direction. A stage rotation mechanism 222 that rotates in the inside, a stage position correction mechanism 223 that slightly moves the stage 221 in the X direction, and a stage lift that moves the stage 221 in the Z direction and is connected to the stage unit moving device 23 A mechanism 224 is provided.

  FIG. 5 is a diagram showing a flow of processing for printing the solder paste 81 on the FPC 9. In the printing apparatus 1 of FIG. 1, first, the transport tray 8 holding the FPC 9 is carried into the printing apparatus 1 by the loader 21 (step S11).

  FIG. 6 is a diagram illustrating a plurality of FPCs 9 held on the transfer tray 8. As shown in FIG. 6, the plurality of FPCs 9 are arranged in a predetermined direction and adhered to an adhesive rubber on the transport tray 8, and a wiring pattern is formed on each FPC 9. Further, predetermined marks 91 for determining a reference position (for position recognition) are formed at the four corners of each FPC 9. In the following description, an ideal (that is, design) arrangement of a plurality of FPCs 9 arranged at predetermined intervals and postures (orientations) is referred to as a reference arrangement.

  The transport tray 8 is transported in the (+ X) direction by the loader 21, further transported by a pair of transport rail portions 25 a and 25 b between the loader 21 and the unloader 24, and in front of the printing unit 4 (hereinafter referred to as “initial” To "Position"). At this time, the movement of the transport tray 8 is locked in front of the printing unit 4 by the stopper. Then, a setting pin of the stage unit 22 is inserted into a hole (not shown) provided in the transfer tray 8 so that the transfer tray 8 is positioned. Thereafter, the space between the transport rail portions 25a and 25b is narrowed, and the transport rail portions 25a and 25b are brought into contact with the side surfaces of the transport tray 8, whereby the posture of the transport tray 8 is regulated, and the stage 221 is lifted and sucked. The transfer tray 8 is set on the stage 221 through the plate (step S12).

  The stage unit 22 is moved to the image acquisition unit 3 together with the conveyance rail units 25a and 25b by the stage unit moving device 23 (step S13), and the printing reference positions for the plurality of FPCs 9 are acquired (determined) (step). S14). The reference position of the FPC 9 is used for positioning with respect to the screen 41 in processing to be described later in the printing unit 4. The process for determining the reference position in step S14 will be described in detail after the description of the overall process in the printing apparatus 1. Here, the “reference position” refers to each of the FPCs 9 that are arranged and held on the transfer tray 8 and maintained in an integral arrangement relationship with each other in the subsequent processing, for example, printing processing. This is a common reference position used for positioning the FPC 9 in a different state.

  When the reference position is determined, the stage unit 22 moves to the printing unit 4 (step S15), and the screen 41 and the transport tray 8 shown in FIGS. 3 and 4 are aligned based on the reference position. (Step S16). Specifically, the stage 221 is slightly moved in the Y direction by the stage unit moving device 23 so that the center of the area occupied by the plurality of FPCs 9 coincides with the center of the screen 41, and the X position is corrected by the stage position correcting mechanism 223. Move slightly. Further, the stage rotation mechanism 222 is also controlled as necessary, and the postures (corresponding to the rotation angles) of the plurality of FPCs 9 are adjusted with respect to the screen 41. Subsequently, the stage 221 is raised by the stage elevating mechanism 224, and the transfer tray 8 is brought into contact with the main surface on the (−Z) side of the screen 41 with the FPC 9 interposed therebetween (step S17). 3 and 4 show a state in which the transport tray 8 is in contact with the screen 41, and illustration of the transport rail portions 25a and 25b is omitted. Actually, the transport rail portions 25 a and 25 b have a height that does not interfere with the screen 41.

  When the FPC 9 on the stage 221 contacts the screen 41, as shown in FIG. 4, the first squeegee 431a is lowered by the squeegee lifting mechanism 432a in the head portion 43 that is positioned on the (−Y) side of the opening 411 in advance. The lower end of the first squeegee 431 a abuts on the (+ Z) side main surface of the screen 41. At this time, the second squeegee 431b is positioned in advance at a predetermined height away from the main surface of the screen 41 on the (+ Z) side. Then, the first squeegee 431a is pressed against the screen 41 with a predetermined pressing force by the pressing mechanism 433a.

  Subsequently, the first squeegee 431 a and the second squeegee 431 b move together with the head portion 43 along the main surface of the screen 41 toward the (+ Y) side. At this time, the first squeegee 431a moves in contact with (pressed on) the screen 41, and pushes the solder paste 81 on the screen 41 in the (+ Y) direction (squeegeeing) the opening of the screen 41. 411 is filled. As described above, when the head moving mechanism 44 moves the first squeegee 431a on the screen 41, the solder paste 81 accumulated on the screen 41 is printed on the plurality of FPCs 9 through the openings 411. (Step S18).

  When the filling of the opening 411 with the solder paste by the first squeegee 431a is completed, the pressing mechanism 433a releases the pressing of the first squeegee 431a against the screen 41, and the squeegee lifting mechanism 432a raises the first squeegee 431a to raise the screen 41. Get away from. Thereafter, the stage 221 is lowered by the stage elevating mechanism 224, the FPC 9 is separated from the screen 41 while the solder paste filled in the opening 411 is adhered on the main surface, and the stage 22 is moved to the initial position (step S19). ). The transfer tray 8 is transferred from the stage 221 to the unloader 24, and the transfer tray 8 is unloaded (step S20).

  Although detailed description is omitted, when printing is performed on the FPC 9 on the next transport tray 8, an operation in which the first squeegee 431a and the second squeegee 431b are switched in the printing operation is performed. Done.

  FIG. 7 is a diagram illustrating the FPC 9 after printing. As shown in FIG. 7, each of the plurality of FPCs 9 is printed with a pattern 82 (for example, a plurality of electrode patterns formed at a pitch of 400 μm) of solder paste at a predetermined position. The FPC 9 carried out from the unloader 24 is sequentially mounted and reflowed with electronic components by subsequent devices, whereby the mounting of the electronic components on the FPC 9 is completed. In FIG. 7, one mounted electronic component 90 is illustrated by a two-dot chain line, and the FPC 9 is provided with a circuit including the electronic component 90 by mounting the electronic component 90 in all necessary portions. It becomes a substrate.

  Next, the process for determining the reference position in step S14 in FIG. 5 will be described. FIG. 8 is a diagram showing the flow of processing for determining the reference position, and shows the processing performed in step S14.

  When the transfer tray 8 on the stage 221 moves to the image acquisition unit 3 (FIG. 5: Step S13), a plurality of predetermined reference position determination marks (hereinafter referred to as “target marks”) on the plurality of FPCs 9. Each image 91 is imaged. For example, as shown in FIG. 9, it is predetermined that the left two marks 91a and 91b on the left FPC 9 and the right two marks 91c and 91d on the right FPC 9 are used as target marks. 2, the imaging position of the imaging unit 31 is sequentially aligned in the vicinity of the four target marks 91a to 91d by the stage unit moving device 23 and the imaging unit moving device 32 in FIG. 2, and the four target marks 91a to 91d. Each image (hereinafter referred to as “mark image”) is acquired. The mark image is output to the control device 5, and the mark position acquisition unit 51 performs pattern matching with a pattern registered in advance in the control device 5 on each mark image, thereby providing 4 provided on the plurality of FPCs 9. The respective positions of the target marks 91a to 91d, that is, the position coordinates on the XY plane are acquired (step S21). In the following description, it is assumed that four target marks 91a to 91d are set on a plurality of FPCs 9, but the number of target marks is not limited as long as the number is three or more. Further, there is no particular limitation as to which mark 91 is selected as the target mark from among the plurality of marks 91, but considering that the reference position is determined using the selected mark 91, they are further apart from each other. It can be said that it is preferable to select the mark 91 at the position as the target mark because the reference position can be determined with higher accuracy.

  Here, the relationship between the holding state of the FPC 9 on the transport tray 8 and the positions of the target marks 91a to 91d will be described. FIG. 10 is a view showing an example of three FPCs 9 arranged and held on the transfer tray 8. 11A and 11B are views illustrating a part of the FPC 9 held on the transfer tray 8, FIG. 11A is a view showing a part of the FPC 9 viewed from the main surface side, and FIG. It is a figure which shows a mode seen from.

  As indicated by the alternate long and short dash line in FIG. 10, the FPC 9 arranged on the right side of the three FPCs 9 arranged and held on the carrying tray 8 is held on the carrying tray 8 in a slightly rotated posture (orientation). In this case, the positions of the target marks 91c and 91d are similarly rotated, and the positions of the three FPCs 9 in the reference array (that is, the positions of the target marks 91c and 91d indicated by solid lines in FIG. 10). ). Further, as indicated by a broken line in FIG. 10, even when the size of the right FPC 9 is expanded and contracted, the positions of the target marks 91c and 91d are shifted from the positions in the reference array. Further, as shown in FIG. 11B, when the FPC 9 is warped on the transport tray 8, the position of the target mark 91 viewed from the main surface side is warped as shown in FIG. 11A. If it is not (ie, it is a position in the reference array and is shown by a two-dot chain line in FIGS. 11A and 11B), it is shifted by a distance d1. Further, such warpage or bending that occurs in the FPC 9 may also be caused by warpage or bending of the transport tray 8 itself.

  In the misalignment mark specifying unit 52, six line segments L1 to L6 are obtained by connecting two target marks of the four target marks 91a to 91d shown in FIG. 9, and the lengths of the line segments L1 to L6 are obtained. The length (length dimension) is required. And the length of each line segment L1-L6 is compared with the upper limit value and lower limit value which are the corresponding threshold values set beforehand, ie, the 1st tolerance, and the length of each line segment L1-L6 is the 1st above-mentioned. It is confirmed whether or not it is within the allowable range (step S22). Here, the allowable range of the length of each line segment is set based on the length of each line segment between target marks in the reference array. Therefore, as shown in FIG. 10 or FIG. 11, when the FPC 9 having the target marks 91a to 91d is deformed, rotated, warped or the like, the length is determined to be out of the allowable range depending on the degree. . In this case, it is determined that printing is not performed for each FPC 9 on the transport tray 8 (step S23), and printing processing for each FPC 9 is stopped (step S24). The determination result is notified to the operator (along with a mark image if necessary), and the improperly held FPC 9 is replaced with the transfer tray 8, and the operation returns to step S21, or all of them are returned. The FPC 9 is peeled off from the transfer tray 8, and the processing for this tray is skipped, and the operation is returned to step S11. Furthermore, adjustment of processes that cause deformation, rotation, warpage, etc. of the FPC 9 such as a process of placing the FPC 9 on the transport tray 8 performed before the processing in the printing apparatus 1 is performed as necessary. Is called. That is, step S23 is a step of determining whether or not the printing process scheduled to be executed in the subsequent step can be started based on whether or not the condition within the first allowable range is satisfied. Can do.

  Next, in the FPC 9 of FIG. 9, when it is confirmed that the lengths of all the line segments L1 to L6 are within the first allowable range (step S23), the lengths of the line segments L1 to L6 are as described above. It is compared with upper and lower limits that define another range that is substantially narrower than the first tolerance range, i.e., the second tolerance range. When there is an abnormal line segment whose length is outside the second allowable range, the abnormal line segment is specified, and the target mark in which the positional deviation has occurred from the combination of the abnormal line segment is detected. It is specified (step S25).

  A specific method for identifying a target mark in which a positional deviation has occurred from a plurality of such abnormal line segments will be described with reference to a table for identifying a positional deviation target mark shown in FIG. In the table shown in FIG. 14, for each of the line segments L1 to L6, “x” is shown when the value is equal to or higher than the upper limit value or lower than the lower limit value (that is, outside the second allowable range), and smaller than the upper limit value. In addition, when it is larger than the lower limit value (that is, within the second allowable range), it is expressed as “◯”, and the target mark in which the positional deviation specified in the column of the exclusion mark has occurred is indicated by a reference numeral. FIG. 14 shows only a part of all possible combinations. For example, when the line segments L1, L2, and L5 are specified as abnormal line segments, the target mark 91a is specified as the target mark in which the positional deviation has occurred from FIG.

  When a plurality of FPCs 9 are arranged in a substantially standard arrangement or when the FPC 9 having the target marks 91a to 91d is deformed, rotated, warped, etc., the degree is small, the target mark where the positional deviation has occurred is specified. Not (that is, the number of target marks in which positional deviation has occurred is zero) (step S26), and the reference position is obtained from the four target marks 91a to 91d (step S27). When a part of the warp occurs as in the FPC 9 shown in FIG. 11A and FIG. 11B, one target mark in which a positional deviation has occurred is specified (step S28), and the reference position is determined from the remaining three target marks. Is obtained (step S29). Furthermore, when a large rotation, deformation, or the like occurs in one FPC 9 as shown in FIG. 10, two target marks in which positional misalignment has occurred are specified (step S30), and the reference is determined from the remaining two target marks. A position is obtained (step S31).

  In addition, as a method for determining the reference position from a plurality of target marks as described above, various methods can be applied. For example, in the case where the reference position is determined from two target marks, the line segment connecting the two target marks is divided into two equal parts with respect to this line segment in a predetermined direction. A position separated by a distance is determined as a reference position. More specifically, in the case where the two target marks are the target marks 91a and 91b, the direction is perpendicular to the line segment from the midpoint of the line segment connecting the two, and A position away from the design distance obtained from the reference array in the direction toward the center of the transport tray 8 is determined as the reference position. Further, along with the determination of the reference position, the line segment connecting the two target marks is compared with the line segment corresponding to the line segment in the reference array, and the angle shift amount in the XY plane is calculated. The angle shift amount thus stored is stored and held in association with the reference position, and then used in alignment.

  Further, for example, in the case where the reference position is determined from three or more target marks, two target marks that are further away from each other are selected from the target marks, and the above-mentioned 2 The reference position can also be determined by using a method for determining the reference position from the individual target marks.

  Alternatively, instead of such a case, the center of gravity can be obtained from three or more target marks, and the center of gravity can be determined as the reference position. For example, when the reference position is determined from the four target marks 91a, 91b, 91c, and 91d shown in FIG. 9, the center of gravity P1 that is the center of gravity can be determined as the reference position. Note that it is only necessary to determine the reference center obtained from a plurality of target marks as the reference position, and instead of the case where the center of gravity is used, for example, the case where the outer center is used may be used.

  When the reference position is determined in this way, the processing after step S15 in the flowchart of FIG. 5 is sequentially performed. Further, since the reference position is determined by such a method, it is possible to appropriately print the solder paste pattern 82 on at least the other FPC 9 in which no rotation or deformation has occurred. In particular, in the printing process, since the screens 41 are arranged on the upper surfaces of the respective FPCs 9, the lifting and warping generated in the FPCs 9 are corrected by pressing the screens 41. Printing can be performed appropriately.

  On the other hand, when there are three or more target marks identified as having been misaligned, that is, when there are one or less target marks determined to have no misalignment (step S30), It is determined that the reference position cannot be determined from the target mark, and the printing process for the FPC 9 is stopped (step S32). Note that such a determination result is notified to the operator. Upon receiving such notification, the operator replaces the improperly held FPC 9 with the transfer tray 8 and then returns to step S21 or removes all the FPCs 9 from the transfer tray 8. The processing for the tray 8 can be skipped and the operation can be returned to step S11.

  In the reference position determination process as described above, the lengths of a plurality of line segments connecting two target marks out of three or more target marks are compared with the corresponding (second) threshold value. The Thereby, the target mark in which the positional deviation has occurred can be specified easily and accurately, and the reference position for performing printing related to the mounting of the electronic component on the FPC 9 can be accurately determined. Note that the target mark in which the positional deviation has occurred does not necessarily need to be identified by referring to a table as shown in FIG. 14 using the comparison result between the length of each line segment and the threshold value. From the comparison result between the threshold value and the threshold value, the target mark in which the positional deviation has occurred may be specified by a predetermined arithmetic method. Further, in the above description, the processing for specifying the target mark in which the positional deviation has occurred using all the six line segments respectively connecting the four target marks has been described. However, the target mark in which the positional deviation has occurred is specified. If possible, it is not always necessary to use all the line segments. For example, with respect to four target marks, the above-described positional deviation occurred using four line segments that form a quadrangle formed from these four target marks and a line segment that forms one diagonal line. The target mark can also be specified.

  The method of identifying the target mark in which such a positional shift has occurred (step S25) is not limited to the above case. Here, another example will be described as a method of identifying the target mark in which the positional deviation has occurred.

  First, in step S23 of FIG. 8, when it is determined that the lengths of all the line segments L1 to L6 are within the first allowable range (that is, it is determined to perform the printing process for the FPC 9), As shown in FIG. 9, the center of gravity P1 of the positions of the four target marks 91a to 91d is obtained by calculation and prepared. Then, the distance between the center of gravity P1 and each of the four target marks 91a to 91d is obtained, and an upper limit value and a lower limit value (that is, a second allowable range), which are predetermined threshold values, are determined. By comparing, it is confirmed whether or not it is within the second allowable range.

  Here, the upper limit value and the lower limit value in the second allowable range are determined based on the distance between the center of gravity of the position of the target mark in the reference array and each target mark. Then, the four target marks 91a to 91d that have the obtained distance outside the allowable range are specified as the target marks in which the positional deviation has occurred (step S25). In the example shown in FIG. 9, since the target marks 91a to 91d are located at the vertices of the rectangle, the distance between the center of gravity P1 and each of the four target marks is the same, and the positional deviations of the target marks 91a to 91d are shifted. It is possible to detect appropriately (that is, with the same degree of accuracy) using the same upper limit value and lower limit value.

  In the above method, the position of one of the target marks is shifted, and the position of the center of gravity P1 obtained from each position is also shifted. However, all the target marks are present at approximately predetermined positions by steps S22 and S23 ( In other words, since it is guaranteed that the condition of being within the first allowable range is satisfied), by obtaining the distance between the center of gravity P1 and each of the target marks 91a to 91d, the position shift of the target mark can be easily and accurately performed. It becomes possible to specify specifically. Further, by using the center of gravity P1, not only the target mark in which the positional deviation has occurred but also the type of deformation of the FPC 9 (so-called deformation mode) can be grasped at the same time, and more information can be provided to the operator. it can. In particular, such a method using the center of gravity has an advantage that the calculation load in the control device 5 associated with the processing can be reduced because the target mark in which the positional deviation has occurred can be identified more easily. In particular, when there is a low possibility of multiple target marks with misalignment, a technique using the center of gravity that can reduce the computational load is effective. On the contrary, the misalignment mark is reliably detected with higher accuracy. In the case where it is desired to specify, the method using the length of the above-mentioned line segment is effective. In addition, in such a method using the center of gravity, the center of gravity is used as an example of the reference center of each target mark, and instead of using the center of gravity, other reference centers, for example, the number of target marks, etc. Can also use a reference center such as an outer center.

  In addition to such another example, there is a method for specifying a target mark in which a positional deviation has occurred. For example, instead of using a line segment connecting each of a plurality of target marks, an angle formed by a pair of two line segments is obtained, and this angle is compared with that in the reference array. Conceivable. However, in the case of making the comparison judgment using only the angle data, in order to eliminate the case where the similar figure is judged to be the same figure, the length data is combined with the angle data. It is desirable to make the above comparison. For example, when four target marks are used, the angle between the length of four line segments and one set of line segments is obtained, or the length of three line segments and two sets of line segments is obtained. The angle formed may be determined and compared to that in the reference sequence. That is, the positional deviation mark specifying unit 52 obtains a relative positional relationship between three or more target marks on the plurality of FPCs 9 held on the transport tray 8 and compares the relative positional relationship with a predetermined reference positional relationship. Any method may be used as long as the target mark in which the positional deviation has occurred is specified. Similarly, in step S23 of FIG. 8, the relative positional relationship between the three or more target marks is obtained by a method other than using the length of the line segment connecting the target marks, and a predetermined reference and It may be determined whether to execute the subsequent process by comparing with the positional relationship.

  Then, reference positions for a plurality of FPCs 9 are obtained based on two or more target marks excluding target marks that have been misaligned from three or more target marks. Thereby, the target mark in which the positional deviation has occurred can be easily identified, and the reference position when performing the printing process, which is one of the processes related to mounting the electronic component on the FPC 9, is changed, rotated, warped, etc. It is possible to determine with high accuracy while reducing the influence of the above. As a result, the screen 41 and the FPC 9 are aligned based on the determined reference position, so that the solder paste 81 can be printed at a predetermined position on the FPC 9 with high accuracy. As a result, the quality of the FPC 9 (circuit board) after electronic component mounting can be improved.

  Further, in the printing apparatus 1, the lengths of a plurality of line segments obtained by connecting two target marks of three or more target marks before processing in the printing unit 4 correspond to the reference array. It is compared with the length, and based on the comparison result, it is determined whether or not to execute processing in the subsequent printing unit 4 for the plurality of FPCs 9. Accordingly, it is possible not only to prevent the printing related to the mounting of the electronic component from being performed wastefully, but also to eliminate the waste of executing the reference position determination process that is no longer necessary. Even in such a process, a reference center assumed from the four target marks in the reference array, for example, the center of gravity (that is, the center of gravity of the four target marks in the design) is prepared, and the center of gravity and each actual target are prepared. It may be a case where a comparison determination is made as to whether or not to execute processing in the subsequent printing unit 4 using the distance between the marks.

  FIG. 12 is a diagram showing still another example of the process of determining the reference position, and shows a process added between step S21 and step S22 of FIG. In still another example of the reference position determination process, in the process preceding printing, the FPC 9 in which a large deviation occurs in the formed pattern, the FPC 9 having a defective pattern, or the like is excluded from the mounting target of the electronic component in advance. In addition, a defective mark (bad mark) indicating that fact is given in advance to a predetermined position on the defective substrate. When the position of the target mark on the FPC 9 is acquired (FIG. 8: step S21), the position of the defective mark on each FPC 9 by the imaging unit 31 (exactly, the position of the defective mark existing when the substrate is a defective substrate). ) Is also imaged, and the FPC 9 in which a defect mark is present is identified as a defective substrate in the control device 5 of the printing apparatus 1 (step S41). As described above, when the defective substrate is specified in the printing apparatus 1, the target mark on the defective substrate is ignored in the processing to be executed later.

  For example, when one FPC of the three FPCs 9 held on the transfer tray 8 is specified as a defective substrate (that is, the other two FPCs are not defective substrates), FIG. In step S22, the calculation of the length of the line segment related to the target mark provided on the defective substrate is omitted, and the determination is not made in step S23. Also in step S25, it is not determined whether or not a positional deviation has occurred with respect to the target mark on the defective substrate. For example, when four target marks are set in total on the plurality of FPCs 9 on the transfer tray 8, and the FPC 9 having two target marks is a defective substrate, the remaining two target marks are set. Whether or not a positional deviation has occurred is specified. If no positional deviation occurs in either of the two target marks (step S30), a reference position is obtained from the two target marks (step S31), and even one of the positional deviations occurs. In this case (step S30), the printing process for each FPC 9 is stopped (step S32), and as described above, the FPC 9 is replaced as necessary, or all the FPCs 9 are removed, and then step S11. Return to.

  As described above, in the example in which the steps of FIG. 12 are added to the respective steps of FIG. 8, a defective substrate is identified by imaging a predetermined position of each FPC 9 on the transfer tray 8, and among the plurality of FPCs 9. Only the target mark provided on a substrate other than the defective substrate is handled as a calculation target in the misalignment mark specifying unit 52. This makes it possible to efficiently determine the target mark that should be used for determining the reference position.

  Note that the process of identifying the defective substrate in step S41 may be performed at another stage as long as it is performed before the process of identifying the target mark in which the positional deviation has occurred (step S25). For example, it may be performed between step S13 in FIG. 5 and step S21 in FIG. In this case, imaging of the target mark on the defective substrate can be omitted, and the time required for step S21 can be shortened. Further, the defective board that is excluded from the electronic component mounting target in advance does not necessarily need to be specified by the defective mark. For example, information indicating the defective board in association with the transfer tray 8 is transmitted from the upstream apparatus to the control apparatus 5. In this case, a defective substrate may be specified.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

  The FPC 9 held on the transport tray 8 is not necessarily an independent FPC 9 as shown in FIGS. 6, 7, and 10, and as shown in FIG. 13, a sheet shape in which a plurality of FPCs 9 are arranged in series. It may be. The circuit board to be printed is not necessarily an FPC, and may be a rigid board on which wiring is formed, for example.

  The printing apparatus 1 may be provided with a mechanism that slightly moves the screen 41 in the X direction and the Y direction so that the screen 41 and the transport tray 8 are aligned. The printing apparatus 1 can also be used for printing other conductive materials and other bonding materials for mounting electronic components such as adhesives for fixing other electronic components besides printing solder paste.

  The member that holds the circuit board can hold only the outer edge of the circuit board, for example, in addition to the transfer tray 8. Further, it is not always necessary to hold a plurality of circuit boards on the transfer tray 8, and only one circuit board may be held.

  In the above embodiment, the imaging unit 31 and the mark position acquisition unit 51 of the control device 5, the position shift mark specifying unit 52, and the reference position determination unit 53 determine reference positions for a plurality of circuit boards held on the transport tray 8. A function as a reference position determination device is realized, and this function is particularly suitable for printing in which a plurality of circuit boards are collectively processed. For example, flip-chip mounting of electronic components on a ceramic substrate, etc. It can also be used for other processes related to mounting electronic components on the circuit board held on the transfer tray 8.

  In addition, in the reference position determination processing for electronic component mounting in FIG. 8, processing for determining whether or not to perform printing on the circuit board (FPC 9) in steps S <b> 21 to S <b> 23 is another process related to mounting electronic components. May be applied.

(Example)
Here, the reference position determination process (the process shown in the flowchart of FIG. 8) in the above embodiment will be described below using an example using specific numerical values. In the present embodiment, for the purpose of facilitating understanding of the processing, numerical examples that are more emphasized with respect to numerical values to be used, allowable ranges, and the like are used.

First, FIG. 15 schematically shows the positional relationship (reference data) of each target mark in the reference array (that is, in design) used in this embodiment. As shown in FIG. 15, in this embodiment, a total of four target marks of target marks A ₀ , B ₀ , C ₀ , and D ₀ are used, and the following lines are used by using the respective target marks. The length of the minute and the position of the center of gravity are set as reference data.

[Reference data]
Target mark A ₀ = (0,0)
Target mark B ₀ = (100, ₀ )
Target mark C ₀ = (100, 100)
Target mark D ₀ = (0,100)
Line segment C ₀ D ₀ = 100
Line segment A ₀ D ₀ = 100
Line segment A ₀ B ₀ = 100
Line segment B ₀ C ₀ = 100
Line segment B ₀ D ₀ = 141.4
Line segment A ₀ C ₀ = 141.4
Center of gravity G ₀ = (50, 50)

Next, a schematic diagram of FIG. 16 shows a positional relationship between the four target marks A ₁ , B ₁ , C ₁ , and D ₁ in the FPC manufactured based on such reference data. The positional relationship is acquired in the process of step S21 in FIG. 8, that is, acquired based on the captured image. Note that the target marks A ₀ , B ₀ , C ₀ , and D ₀ as the reference array shown in FIG. 15 correspond to the target marks A ₁ , B ₁ , C ₁ , and D ₁ as actual positions in FIG. is doing.

As shown in FIG. 16, four for the target mark C ₁ of the target mark its actual position coordinates has a (90, 90), displaced in its position coordinates are generated with respect to the reference data Yes. Such displacement occurs, for example by such floating near the target mark C ₁ in the FPC occurs. Under such circumstances, the comparison processing in steps S22 and S23 of FIG. 8 is performed with the allowable range of the line segment length as a reference of ± 8% as the first allowable range. The result data 1 of the comparison process is as follows.

[Comparison processing result data 1]
Line segment C ₁ D ₁ = 90.6 (-9.4%) → Out of tolerance
Line segment A ₁ D ₁ = 100 (0%)
Line segment A ₁ B ₁ = 100 (0%)
Line segment B ₁ C ₁ = 90.6 (-9.4%) → Out of tolerance
Line segment B ₁ D ₁ = 141.4 (0%)
Line segment A ₁ C ₁ = 127.3 (-10.0%) → Out of tolerance

As shown in the comparison processing result data 1, the lengths of the line segment C ₁ D ₁ , the line segment B ₁ C ₁ , and the line segment A ₁ C ₁ exceed the first allowable range. The process is stopped, that is, the printing process scheduled to be performed for the FPC is stopped.

Here, another example of the positional relationship between the respective target marks acquired for the similar FPC is shown in the schematic diagram of FIG. Note that the target marks A ₀ , B ₀ , C ₀ , and D ₀ as the reference array shown in FIG. 15 correspond to the target marks A ₂ , B ₂ , C ₂ , and D ₂ as actual positions in FIG. is doing.

As shown in FIG. 17, the target mark C ₂ of the four target marks has become its actual position coordinates and (95, 95), deviation occurs in the coordinate with respect to the reference data . Under such circumstances, the comparison processing in steps S22 and S23 of FIG. 8 is performed with the allowable range of the line segment length as a reference of ± 8% as the first allowable range. The result data 2 of the comparison process is as follows.

[Comparison processing result data 2]
Line _{C 2 D 2 = 95.1 (-4.9} %)
Line segment A ₂ D ₂ = 100 (0%)
Line segment A ₂ B ₂ = 100 (0%)
Line segment B ₂ C ₂ = 95.1 (−4.9%)
Line segment B ₂ D ₂ = 141.4 (0%)
Line A ₂ C ₂ = 134.4 (−5.0%)

  As shown in the comparison result data 2, it is determined that the lengths of all the line segments are within the first allowable range (step S23). If it is determined that the position is within the first allowable range as described above, then in step S25, a specific process for the target mark in which the positional deviation has occurred is performed. As the identification method, various methods can be applied as described above. As an example, the method is described by applying a method that uses the center of gravity.

Specifically, four target marks _{A 2,} B 2, _{C 2,} and obtains the coordinates of the center of gravity _{G 2} by using the position coordinates of _{D 2,} the center of gravity G2 and the target mark _{A 2,} B 2, _{C 2} , and obtains the distance between the D _2, compares the distance with the reference data in the reference sequence of Figure 15. As a judgment criterion in the comparison, the second allowable range was set to ± 4%. The comparison processing result data 3 is as follows.

[Comparison processing result data 3]
Center of gravity G2 = (48.75, 48.75)
Line segment A ₂ G ₂ = 68.94 (-2.50%)
Line segment B ₂ G ₂ = 70.73 (+ 0.03%)
Line segment C ₂ G ₂ = 65.40 (−7.50%) → outside allowable range
Line segment D ₂ G ₂ = 70.73 (+ 0.03%)

As shown in the comparison result data 3, since the length dimension of the line segment C ₂ G ₂ exceeds the second allowable range, in step S25, the target mark C ₂ is the target mark in which the positional deviation has occurred. Identified. Thereafter, in step S28, it is determined that there is one mark that has been displaced, and the reference position is calculated and determined using the remaining three marks, that is, the target marks A ₂ , B ₂ , and D _2. The

For example, in the case that positional displacement in the target mark C ₂ is generated by the floating of the FPC, in the printing process of the subsequent screen is placed in FPC, the floating of the FPC is corrected Although the, in the case that the reference position is determined using the target mark C ₂ includes the reference position in the FPC lifting is corrected, it is an error may occur between the determined reference position, It becomes difficult to perform highly accurate positioning.

However, even in this case in such misalignment to a subject mark C ₂ is generated, to the exclusion of target mark C ₂ that misalignment occurs, to determine the reference position from the rest of the target mark Therefore, highly accurate positioning can be performed reliably and simply.

  It is to be noted that, by appropriately combining arbitrary embodiments of the various embodiments described above, the effects possessed by them can be produced.

  Although the present invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included therein, so long as they do not depart from the scope of the present invention according to the appended claims.

  The present invention can be used for various processes related to mounting electronic components that use a reference position for positioning with respect to one or a plurality of circuit boards.

1 is a diagram illustrating a configuration of a printing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of an image acquisition unit included in the printing apparatus of FIG. It is a front view which shows the structure of the printing part with which the printing apparatus of FIG. 1 is provided. It is a right view which shows the structure of the said printing part. It is a flowchart which shows the flow of the process which prints a solder paste with respect to each circuit board by the said printing apparatus. It is a figure which shows each circuit board (circuit board before printing) hold | maintained at the conveyance tray of the said printing apparatus. It is a figure which shows each circuit board after printing. 6 is a flowchart showing a flow of processing for acquiring a reference position of each circuit board in the printing apparatus. It is a figure which shows each circuit board on a tray for conveyance, Comprising: It is the figure which displayed the line segment comprised by connecting each object mark. It is a figure which shows each circuit board on a tray for conveyance, Comprising: It is a figure which shows the state which the position shift has produced in the circuit board of 1 sheet. It is a figure which shows a part of circuit board on the tray for conveyance, Comprising: It is a top view which shows the state which the lift has arisen in the edge part of the said circuit board. It is a figure which shows a part of circuit board on the tray for conveyance, Comprising: It is a side view which shows the state which the lift has arisen in the edge part of the said circuit board. It is a flowchart which shows a part of flow of the reference position determination process which added the step which specifies a defective board | substrate. It is a figure which shows each rigid board | substrate arrange | positioned on the tray for conveyance. It is a figure which shows the table | surface for pinpointing the target mark which the position shift generate | occur | produced in FPC from the line segment which has abnormality in a length dimension. It is a schematic diagram for demonstrating the Example of the reference | standard position determination process concerning the said embodiment, and is a figure which shows the positional relationship (reference | standard data) of each object mark in the reference | standard arrangement | sequence of FPC. In the said Example, it is a schematic diagram which shows the positional relationship of each object mark recognized and acquired. In the said Example, it is a schematic diagram which shows another example of the positional relationship of each object mark recognized and acquired.

Explanation of symbols

1 Printing device 8 Transport tray 9 Circuit board (FPC)
23 Stage unit moving device 31 Imaging unit 41 Screen 44 Head unit moving mechanism 51 Mark position obtaining unit 52 Position shift mark specifying unit 53 Reference position determining unit 81 Solder paste 91, 91a to 91d Target mark 223 Stage position correcting mechanism 411 Opening 431a, 431b Squeegee L1-L6 Line segment P1 Center of gravity

Claims (5)

In the group reference position determination method that determine a reference position of the circuit board,
Obtains the positional relationship of three or more reference position determination for mark provided in the circuitry substrate,
It is compared with the positional relation of the positional relationship between the pre-Me-determined criteria to identify the warping or reference position determining marks located in the area caused a deformation of the circuit board,
Determining whether there are two or more reference position determination marks excluding the specified reference position determination marks;
When it is determined that there are two or more reference position determination marks excluding the specified reference position determination marks, the two or more reference position determination marks excluding the specified reference position determination marks are used. standards positioning how to determine the criteria position of the circuit board. In specifying the reference position determination mark located in the warped or deformed region of the circuit board ,
It determined the length of the plurality of the line segment connecting the position of the three or more reference positioning marks Noso respectively,
Identifying warping or reference position determining marks located in the area caused a deformation of Riue SL circuit board by to Sato Cho compared corresponding to each said segment length defined Me pre each said segment group reference position determination method according to claim 1. The reference position determination method according to claim 1 or 2 is performed to determine a reference position with respect to the circuit board,
Press the screen against the circuit board based on the reference position,
A printing method for printing a bonding material via the screen. In a reference position determination device for determining a reference position of a circuit board ,
A positional relationship acquisition unit for determining the positional relationship of three or more reference position determination marks provided on the circuit board;
A specifying unit for specifying a reference position determination mark located in a region where warpage or deformation of the circuit board occurs by comparing the positional relationship with a predetermined reference positional relationship;
A determination unit that determines whether there are two or more reference position determination marks excluding the specified reference position determination marks;
When it is determined that there are two or more reference position determination marks excluding the specified reference position determination marks, the two or more reference position determination marks excluding the specified reference position determination marks are used. A reference position determining unit for determining a reference position of the circuit board;
A reference position determining device. A reference position determining device according to claim 4 for determining a reference position of a circuit board;
Screen,
A pressing device that presses the screen against the circuit board based on the reference position;
An apparatus for printing the bonding material via the screen; and a bonding material printing apparatus.

Images