JP4743172B2 - Solder inspection method - Google Patents

Description

  The present invention relates to a solder inspection method for inspecting a printed state of solder printed on a substrate.

  In mounting electronic components, cream solder is applied to the surface of the substrate prior to mounting the electronic components on the substrate. As a method for applying the cream solder, a screen printing method is widely used. After the printing process, a solder inspection for inspecting the printing state of the cream solder is performed. In this solder inspection, the substrate after screen printing is imaged by a camera, and the imaged result is subjected to image recognition processing to determine whether or not the cream solder is correctly printed at the solder printing position corresponding to the bonding electrode on the substrate. (See, for example, Patent Document 1).

When a printing defect is detected by this solder inspection, the board is discharged from the electronic component mounting line, so that a defect notification is given and the inspection result is displayed on the display monitor. Thereby, the operator can know what kind of printing defect has occurred at which solder printing position of the substrate.
JP-A-6-18237

  By the way, the information obtained by solder inspection is not only used for pass / fail judgment for individual substrates, but also feedback for setting the printing conditions more appropriately, for example, by determining the tendency of specific items of the printing state. It is desirable to use it as information. However, in the conventional solder inspection apparatus, since the inspection result is only displayed for each substrate, it is difficult to effectively use various information obtained by the inspection.

  Accordingly, an object of the present invention is to provide a solder inspection method that can effectively use inspection result information obtained in solder inspection and improve the usefulness of print inspection.

The solder inspection method of the present invention is a solder inspection method for inspecting the printed state of solder for a substrate on which a plurality of solder printing positions are set, and imaging the solder printing position on the substrate after solder printing. A determination step for determining the quality of the printing state based on the imaging result acquired by the imaging step and outputting the determination result; and accumulatively storing the determination result for each solder printing position for a plurality of substrates. seen including a storage step, and a determination result accumulated display step of displaying the determination result of the said accumulated stored for each solder printing positions in visually displaying the on-screen solder printing position as the solder printing position map in the substrate, wherein Solder printing is performed by screen printing in which forward printing and reverse printing are repeated by reciprocating a squeegee on a mask plate, and the determination result accumulation display step In this case, the data type selection frame for each printing direction is operated to display only “NG” generated in the forward direction printing, “from front to back”, and to display only NG generated in the reverse direction printing, “from back to front”. Displaying the combined data of all NGs generated in both the forward and reverse directions. The data for “mixed display”, “front to back” and “back to front” is the same balloon mark on the same screen. The determination result is displayed in association with the printing direction by selecting any one of “same screen display” displayed in a pie chart in the form of the ratio in the graph .

  According to the present invention, determination results of solder inspection are accumulated and stored for each solder printing position for a plurality of boards, and each solder printing position on the screen is visually displayed as a solder printing position map on each solder. By displaying the determination result accumulated and stored for each printing position, it is possible to effectively utilize the inspection result information obtained in the solder inspection and improve the usefulness of the print inspection.

Next, embodiments of the present invention will be described with reference to the drawings. 1 is a front view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a side view of the screen printing apparatus according to an embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to an embodiment of the present invention. FIG. 4 is a diagram for explaining the operation of the screen printing apparatus according to the embodiment of the present invention. FIG. 5 is a plan view of the substrate printing surface of the screen printing apparatus according to the embodiment of the present invention. The block diagram which shows the structure of the control system of the solder test | inspection apparatus incorporated in the screen printing apparatus of one embodiment of FIG. 7, FIG. 7 is a figure which shows the determination result display screen of the solder test | inspection apparatus of one embodiment of this invention, FIG. 8 is a view for explaining the display contents of the determination result display screen of the solder inspection apparatus according to the embodiment of the present invention, and FIG. 9 is a flowchart of the solder inspection method according to the embodiment of the present invention.

  First, the structure of the screen printing apparatus will be described with reference to FIG. 1, FIG. 2, and FIG. In this screen printing apparatus, not only a printing mechanism that prints cream solder at a plurality of solder printing positions on a board on which electronic components are mounted, but also a solder printed state for a board after solder printing, as will be described later. It has a structure that also has a function as a solder inspection apparatus for performing inspection.

  1 and 2, the substrate positioning unit 1 includes a θ-axis table 4 stacked on a moving table composed of a Y-axis table 2 and an X-axis table 3, and a Z-axis table 5 disposed thereon. The substrate holder 6 is provided on the Z-axis table 5 to hold the substrate 8 sandwiched by the clamper 7 from below. The substrate 8 to be printed is carried into the substrate positioning unit 1 by the carry-in conveyor 14 shown in FIGS. By driving the substrate positioning unit 1, the substrate 8 moves in the XY directions and is positioned at a printing position and a substrate recognition position described later. The printed substrate 8 is carried out by the carry-out conveyor 15.

  A screen mask 10 is disposed above the substrate positioning unit 1, and the screen mask 10 is configured by attaching a mask plate 12 to a holder 11. The substrate 8 is aligned with the mask plate 12 by the substrate positioning unit 1 and abuts from below. As shown in FIG. 5A, electrodes 8a, 8b, 8c, and 8d for joining different types of electronic components are provided on the circuit forming surface of the substrate 8.

  On the screen mask 10, a squeegee head 13 is disposed so as to be able to reciprocate in the horizontal direction. As shown in FIG. 2, the squeegee head 13 includes two squeegees 18 </ b> A and 18 </ b> B, and the squeegees 18 </ b> A and 18 </ b> B are moved up and down by a squeegee lifting mechanism 17 held on a horizontal moving plate 16. The printing operation by the squeegee head 13 is performed in a state where the substrate positioning unit 1 holding the substrate 8 is moved to a printing position below the screen mask 10 as shown in FIG.

  In the printing operation, first, the substrate 8 is brought into contact with the lower surface of the mask plate 12, and the cream solder 9 is supplied onto the mask plate 12. Then, by sliding any one of the squeegees 18A and 18B of the squeegee head 13 in contact with the surface of the mask plate 12, pattern holes (not shown) provided in the mask plate 12 are formed on the printing surface of the substrate 8. The cream solder 9 is printed through. As a result, as shown in FIG. 5B, solder printing portions S1, S2, S3, and S4 are formed on the electrodes 8a, 8b, 8c, and 8d, respectively. That is, the electrodes 8 a, 8 b, 8 c, 8 d are a plurality of solder printing positions set on the substrate 8.

  In this screen printing operation, forward direction printing is performed by moving the squeegee 18A from the front side (left side in FIG. 2) to the back side (right side in FIG. 2) (see arrow a), and the squeegee 18B is moved to the back side. In this case, reverse printing in which printing is performed by repeatedly moving from the front side to the front side (see arrow b) is repeatedly executed. As described later, when accumulating and storing the inspection results of the solder inspection, the inspection results are stored in association with the printing direction. The distinction between “forward direction” and “reverse direction” is for convenience.

  A camera 20 is provided above the screen mask 10. As shown in FIG. 3, the camera 20 is horizontally moved in the XY directions by the X-axis table 21 and the Y-axis table 22. The X-axis table 21 and the Y-axis table 22 are camera moving means for moving the camera 20.

  As shown in FIG. 2, the substrate positioning unit 1 is moved in the Y direction from the lower side of the screen mask 10 by the Y-axis table 3 to move the held substrate 8 to the substrate recognition position. In this state, as shown in FIG. 4B, by moving the camera 20 above the substrate 8 held by the substrate positioning unit 1, an arbitrary position of the substrate 8 can be imaged by the camera 20. The camera 20 is an image pickup unit that picks up an image of the solder printing position on the board after the solder printing.

  Next, the configuration of the control system of the solder inspection apparatus incorporated in the screen printing apparatus will be described with reference to FIG. The control unit 23 controls the mechanism unit 26 such as the substrate positioning unit 1 and the screen printing mechanism via the mechanism control unit 25, and controls the CCU (camera control unit) 24 and the display unit 28 that control the imaging of the camera 20. Further, the input from the operation / input unit 27 is controlled. The control unit 23 includes an image processing unit 23a, a pass / fail inspection unit 23b, a statistical processing unit 23c, and a display processing unit 23d as internal functions to be described below, in addition to the function as the overall control device described above.

  The image processing unit 23a receives imaging data acquired by the camera 20 via the CCU 24, and performs predetermined image processing such as solder shape detection. The quality inspection unit 23b inspects the quality of the print state based on the image processing result processed by the image processing unit 23a, and outputs a determination result. The image processing unit 23a and the pass / fail inspection unit 23b serve as a determination unit that determines pass / fail of the print state based on the imaging result of the imaging unit and outputs the determination result.

  When the determination result is output by the determination means, not only the determination as to whether the inspection result is NG, but also the type of printing state failure is output together. The types of printing status are: misalignment where the printing position deviates from the normal position, bleeding that prints out of the normal printing range, the amount of printing is less than the normal state, and incorrect soldering between adjacent solder printing positions. There are bridges that become connected. The statistical processing unit 23c performs a predetermined statistical process by accumulating the determination results output from the pass / fail inspection unit 23b for each substrate. The processing result is output to the display processing unit 23d, and after the display processing is performed by the display processing unit 23d, it is displayed on the display monitor of the display unit 28.

  Next, the storage unit 30 will be described. The storage unit 30 includes an inspection data storage unit 31, an inspection NG cumulative data storage unit 32, and a program storage unit 33. The program storage unit 33 stores processing programs for various processes executed by the control unit 23. The inspection data storage unit 31 stores inspection data used for the pass / fail inspection by the pass / fail inspection unit 23b, that is, solder position data 31a, solder shape data 31b, and inspection threshold data 31c. In the solder position data 31a, the solder print position where the solder is printed on the substrate, here the coordinate data indicating the positions of the electrodes 8a, 8b, 8c and 8d is the solder position data.

  The solder shape data 31b is data related to the shape and amount of solder to be printed on each solder printing section, and here, the area where the solder is printed is stored as the solder shape data. The inspection threshold value data 31c is data indicating an allowable range of variation in the positional deviation of each solder printing unit detected by the image processing unit 23a with respect to the normal position and the actual solder amount with respect to the normal solder amount. If the determined threshold value is not met, an NG determination is made.

  The inspection NG cumulative data storage unit 32 stores the inspection NG cumulative data statistically processed by the statistical processing unit 23c for the NG determination result of the specific item output for each substrate by the pass / fail inspection unit 23b. Here, the frequency of occurrence of NG is stored for each solder printing position on the same type of board in the form of data 32a for printing direction and data 32b for each type of NG. That is, in the printing direction data 32a, the occurrence frequency of NG generated at each solder printing position is stored for each printing direction by the squeegee unit 13, and in the NG type data 32b, the occurrence frequency of NG generated at each solder printing position. Are stored for each NG type.

  Next, the examination NG cumulative display will be described with reference to FIGS. FIG. 7 shows a screen 34 in which the data stored in the examination NG cumulative data storage unit 32 is subjected to display processing by the display processing unit 23 d and displayed on the display monitor of the display unit 28. On the screen 34 that displays NG information, a solder printing position map 35 that visually indicates the solder printing positions on the substrate 8, that is, the positions of the electrodes 8a, 8b, 8c, and 8d, is displayed. In the solder printing position map 35, NG generated on the substrate 8 to be displayed is displayed for each solder printing position.

  Here, by operating the cumulative display button 39, the solder printing position map 35 displays NG generation data for a plurality of boards printed up to that point. Here, as a display method, a method of displaying the balloon mark 36 on the solder printing position map 35 is used. That is, the solder printing position where NG has occurred is displayed according to the position of the balloon mark 36, and the frequency of occurrence is displayed according to the size of the balloon mark 36. By comparing the size of the balloon mark 36 with the size reference field 41 displayed together on the NG display screen 34, the actual frequency of occurrence can be known. By operating the cumulative reset button 40, the stored examination NG cumulative data is reset, and cumulative storage of the determination result is newly started from that point. The occurrence frequency of NG may be determined by the color of the balloon mark 36.

  Next, data display by print direction for displaying the inspection NG accumulated data based on the print direction data 32a will be described. That is, by operating the data type selection frame 37 for each printing direction on the NG display screen 34, four types of display methods shown in FIG. 8A, “front to back” 37a, “back to front” 37b, and “mixed” are displayed. "Display" 37c and "Same screen display" 37d can be selected. “Front to back” 37a and “Back to front” 37b are display methods for only NG generated in forward printing and reverse printing, respectively. “Mixed display” 37c is for forward / reverse printing. Regardless of the generated NG, the combined data is displayed.

  When “same screen display” 37d is selected, as shown in FIG. 8 (a), the data for “front to back” 37a and “back to front” 37b are ratios in the same balloon mark on the same screen. Is displayed as a pie chart. As a result, the cumulative number of NG occurrences and the frequency distributions in the “front to back” 37a and “back to front” 37b can be displayed in a display form with excellent listability that can be grasped as a whole. By displaying NG in association with the printing direction in this way, it is possible to estimate the relationship between the occurrence of NG and the printing direction.

  Next, the inspection NG detailed display will be described. When the balloon mark 36 is displayed on the solder printing position map 35 based on the NG type-specific data 32b by operating the inspection NG detail display button 38 set on the screen 34 for displaying NG information, The generation ratio for each type is displayed as a pie chart within the balloon mark 36.

That is, in the above configuration, the inspection NG cumulative data storage unit 32 is a storage unit that cumulatively stores determination results for each solder printing position for a plurality of substrates, and the display processing unit 23d and the display unit 28 are provided on the substrate. The solder printing position map display means visually displays the solder printing position as a solder printing position map. The statistical processing unit 23c and the display processing unit 23d constitute determination result accumulation display means for displaying the determination result accumulated and stored for each solder printing position on the solder printing position map. The determination result accumulation display means is configured to display the determination result in association with the printing direction and to display the determination result in association with the type of printing state failure.

  Next, with reference to FIG. 9, an execution flow of solder inspection executed by the camera 20, the CCU (camera control unit) 24, and the control unit 23 will be described with reference to FIG. When the solder inspection is started (ST1), necessary data is read from the inspection data storage unit 31 (ST2). Next, a solder print image is acquired by the camera 20 (ST3), the image data is subjected to image processing by the image processing unit 23a, and a solder inspection is performed by the pass / fail inspection unit 23b based on the processing result (ST4).

  Then, the inspection NG is determined (ST5), and if it is NG, a predetermined statistical process is performed by the statistical processing unit 23c. That is, the NG number is counted (ST6), and the accumulated NG number is stored in the inspection NG accumulated data storage unit 32 in correspondence with the solder printing position (ST7). Then, it is determined whether or not the solder position is the last solder (ST8). If not, the process returns to (ST3) and the same processing is repeated.

  If the inspection is not NG in (ST5), the process proceeds to (ST8), where it is confirmed that it is the last solder in (ST8), and the solder inspection is finished (ST9). As described above, in the process of repeatedly executing the solder inspection for a plurality of substrates of the same product type, the data on the frequency of occurrence of NG and the data on the type of NG are accumulated for each solder printing position, and the operator is in the state of occurrence of NG. Is displayed, a screen 34 for displaying NG information is displayed on the display monitor of the display unit 28.

  That is, in the solder inspection method for inspecting the printed state of solder for the substrate 8 on which a plurality of solder printing positions are set, an imaging step of imaging the solder printing position on the substrate 8 after solder printing, and imaging A determination step of determining whether the printing state is good or not based on the imaging result acquired in the step and outputting the determination result; a storage step of accumulating and storing the determination results for each solder printing position for a plurality of substrates 8; And a determination result accumulation display step of displaying the determination result accumulated and stored for each solder printing position on the screen visually displaying the solder printing position as a solder printing position map.

  As a result, it is possible to easily grasp the overall generation tendency of NG at each solder printing position, which is difficult to accurately judge in the conventional solder inspection method that displays only the inspection result for each substrate. Further, it is possible to grasp more detailed contents as necessary, such as the relationship between the NG occurrence status and the printing direction and the NG occurrence distribution by type.

  By analyzing these NG generation tendencies, it is possible to estimate NG generation factors based on empirical data and set printing conditions more appropriately. That is, it is possible to effectively use the inspection result information obtained in the rice field inspection and improve the usefulness of the print inspection.

  The solder inspection method of the present invention has the effect of effectively using the inspection result information obtained in the solder inspection and improving the usefulness of the print inspection, and is used for joining electronic components printed on a substrate. This is useful in the field of inspecting the printed state of solder.

1 is a front view of a screen printing apparatus according to an embodiment of the present invention. The side view of the screen printing apparatus of one embodiment of this invention The top view of the screen printing apparatus of one embodiment of this invention Operation explanatory diagram of a screen printing apparatus according to an embodiment of the present invention The top view of the substrate printing surface by the screen printing apparatus of one embodiment of this invention The block diagram which shows the structure of the control system of the solder inspection apparatus incorporated in the screen printing apparatus of one embodiment of this invention The figure which shows the determination result display screen of the solder inspection apparatus of one embodiment of this invention The figure explaining the display content of the determination result display screen of the solder inspection apparatus of one embodiment of this invention The flowchart of the solder test | inspection method of one embodiment of this invention

Explanation of symbols

8 Substrate 8a, 8b, 8c, 8d Electrode 9 Cream solder 20 Camera 23 Control unit 23b Pass / fail inspection unit 23c Statistical processing unit 23d Display processing unit S1, S2, S3, S4 Solder printing unit

Claims (1)

A solder inspection method for inspecting a solder printing state for a board on which a plurality of solder printing positions are set, an imaging process for imaging the solder printing position on a board after solder printing, and acquired by the imaging process A determination step of determining pass / fail of the print state based on the obtained imaging result, and outputting a determination result; a storage step of accumulating and storing the determination result for each solder printing position for a plurality of substrates; and solder printing on the substrate position look including the determination result accumulated display step of displaying the determination result of the said accumulated stored for each solder printing positions in visually displaying the on screen as solder printing position map,
The solder printing is performed by screen printing in which forward printing and backward printing are repeated by reciprocating a squeegee on a mask plate, and in the determination result accumulation display step, a data type selection frame for each printing direction is operated, “NG from front to back” that displays only NG generated in the forward direction printing, “NG from front to back” that displays only NG generated in the reverse direction printing, all NG generated regardless of forward direction or reverse direction “Same screen”, which displays the combined data, “mixed display”, “front to back” and “back to front” in the form of a ratio in the same balloon mark on the same screen By selecting any one of “display”, the determination result is displayed in association with the printing direction .

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