JP2013187483A - Defect determination method and defect determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the possibility of a defect even in the case that a product has part floating with little floating amount or the wettability of a part electrode a little worse than that of a good part.SOLUTION: A defect determination device 100 includes: solder printing means 10 for printing solder on a substrate; part mounting means 11 for mounting a part on the solder-printed substrate; mounted part position measuring means 12 for measuring part coordinates after the part is mounted, and for calculating a first coordinate deviation from part implementation target coordinates; reflow means 13 for heating the substrate after the part is mounted and for soldering the part; after-reflow part position measuring means 14 for measuring part coordinates after reflow and for calculating a second coordinate deviation from the part implementation target coordinates; and fault determination means 15 for determining the possibility of a defect of the part after reflow on the basis of the first coordinate deviation and second coordinate deviation.

Description

  The present invention relates to a component defect determination method and a defect determination device, and more particularly to a component defect determination method and a defect determination device mounted on a substrate.

  In the mounting of electronic components that consist of solder printing, component mounting, and reflow processes, especially in chip-type electronic components that have electrodes on both ends, component displacement, component floating, and component standing (a phenomenon called Manhattan or Tombstone) Various defects such as are occurring.

  The causes of these defects include a difference in the interfacial tension acting on the electrodes due to the molten solder due to variations in the amount of solder printed on the pads on which the components are mounted and variations in the solder wettability of the component electrodes.

  When these variations are small, the interfacial tension acting on both electrodes moves to near the center between the pads (self-alignment effect). However, if the variation increases, the interfacial tension difference between the two electrodes also increases, and the component has an interfacial tension. It is attracted to the larger one, resulting in defective parts such as part displacement and part floating.

  On the other hand, conventionally, defect determination is performed by inspection after solder printing or appearance inspection after reflow. For component mounting position deviation in visual inspection after reflow, for example, the component position is detected by pattern matching using a reference component image, and the deviation from the component mounting target coordinates (mounting position in the design) is within the allowable range. There is a way to check if there is.

  In addition to the detection by the above pattern matching, the component floating is caused by component floating or insufficient wetting as described in Japanese Patent Laid-Open No. 1-282410 (Japanese Patent Publication No. 6-1173: Patent Document 1). In this case, since the joint part (fillet) between the component electrode and the solder is not formed correctly, the shape of the fillet is measured, and if the fillet is not formed correctly, it is determined as defective, and the defect determination including part floating and insufficient wetting is performed. Has been done.

  However, if the lift of the component with a small lift amount and the wettability of the component electrode are slightly inferior to those of the good product, the difference from the good product is small.In the case of micro components, the fillet itself is small. There was a problem that it was difficult to detect.

JP-A-1-282410

  An object of the present invention is to provide a technique for solving the above-described problems of the prior art, and even when the component lift and the wettability of the component electrode with a small lift amount are slightly inferior to those of a good product, the possibility of failure It is an object of the present invention to provide a defect determination method and a defect determination apparatus that can determine the above.

The defect determination method according to the present invention includes:
Printing solder on the board;
Mounting a component on the printed board of the solder;
Measuring component coordinates after mounting the component and calculating a first coordinate deviation from the component mounting target coordinates;
A reflow step of heating the substrate after mounting the component and soldering the component;
Measuring the component coordinates after the reflow, and calculating a second coordinate deviation from the component mounting target coordinates;
Determining a possibility of a defective part after the reflow based on the first coordinate shift and the second coordinate shift;
It is characterized by having.

Moreover, the defect determination apparatus according to the present invention is
A solder printing means for printing solder on a substrate; and
Component mounting means for mounting a component on the printed board of the solder;
A post-mounting component position measuring means for measuring the component coordinates after mounting the component and calculating a first coordinate deviation from the component mounting target coordinates;
Reflow means for heating the substrate after mounting the component and soldering the component;
A component position measuring unit after reflow that measures the component coordinates after the reflow and calculates a second coordinate deviation from the component mounting target coordinates;
A failure determination means for determining a possibility of a failure of the component after the reflow based on the first coordinate shift and the second coordinate shift;
It is characterized by having.

  According to the present invention, it is possible to determine the possibility of failure even when the component floating amount and the wettability of the component electrode are slightly inferior to those of the non-defective product.

It is a figure which shows the structure of the defect determination apparatus which concerns on embodiment of this invention. It is a figure for demonstrating an example of the method of determining possibility that a component is defective, (a) shows the component mounting position after component mounting, (b) has shown the component mounting position after reflow. . It is a figure for demonstrating an example of the method of determining possibility that a component is defective, (a) shows the component mounting position after component mounting, (b) has shown the component mounting position after reflow. . It is a flowchart for demonstrating the defect determination method which concerns on embodiment of this invention. It is a figure which shows the example of mounting of the component on the board | substrate in a component mounting means. It is a figure which shows an example of the soldering of the components in a reflow means. It is a figure which shows an example of the soldering of the components in a reflow means. It is a figure which shows an example of the soldering of the components in a reflow means. It is a figure which shows an example of the soldering of the components in a reflow means.

  Embodiments of the present invention will be described in detail with reference to the drawings.

  With reference to FIG. 1, the structure of the defect determination apparatus according to the embodiment of the present invention will be described.

  As shown in FIG. 1, the defect determination apparatus 100 images a solder printing unit 10 that prints solder on a substrate, a component mounting unit 11 that mounts a component on a substrate printed with solder, and a substrate on which the component is mounted. The post-mounting part position measuring unit 12 that measures the coordinate deviation between the component position and the component mounting target coordinates, the reflow unit 13 that heats the substrate after mounting the component, and solders the component, and the reflowed board Then, from the post-reflow component position measuring means 14 for measuring the coordinate deviation between the component position and the component mounting target coordinates, and the component position coordinate deviation detected by the post-mounting component position measuring means 12 and the post-reflow component position measuring means 14, There is a failure determination means 15 for determining the possibility of a failure after reflow.

  As described above, in the embodiment of the present invention, in mounting the electronic component on the board, the possibility of the component being defective is determined using the component coordinate information after component mounting and the component coordinate information after reflow.

  Here, with reference to FIG. 2 and FIG. 3, an example of a method for determining the possibility that a part is defective will be described. Here, FIGS. 2A and 3A show the component positions after mounting the components, and FIGS. 2B and 3B show the component positions after reflow. Here, the component positions shown in FIGS. 2B and 3B are the same, and the same result is obtained in the defect determination according to the prior art. As shown in FIGS. 2 and 3, a component 101 is mounted on a substrate having a pad 102.

  As shown in FIGS. 2A and 2B, the component 101 whose component coordinates after the component mounting process greatly deviated from the component mounting target coordinates is close to the center between the pads which are the component mounting target coordinates after the reflow process. If it has moved, a large self-alignment effect appears, so that good solder wettability can be obtained and it can be determined that good soldering has been performed.

  On the other hand, as shown in FIGS. 3A and 3B, a component whose component coordinates after the component mounting process are slightly on the right side of the center between the pads is a component mounting target coordinate after the reflow process. If it moves beyond the center and slightly to the left of the center between the pads, it can be assumed that the right electrode of the component has poor wettability and has been drawn toward the left pad, which may be defective. It is done.

  Therefore, in the embodiment of the present invention, the component coordinates in each are measured from the product image after component mounting and the product image after reflow to determine the coordinate deviation from the component mounting target coordinates, and these coordinate deviations are compared. Thus, the possibility that the part is defective is determined.

  Next, with reference to FIG. 4, the failure determination method according to the embodiment of the present invention will be described. Here, FIG. 4 shows a procedure until components are mounted on the board.

  First, the solder printing means 10 performs solder printing on a board on which no component is mounted, and carries the board to the component mounting means 11 (step 40).

  Next, the component mounting means 11 mounts components on the board carried in from the solder printing means 10 and carries the board to the component position measuring means 12 after mounting (step 41).

  Next, the post-mounting component position measuring unit 12 captures an image of the board carried from the component mounting unit 11, measures the component coordinates, and calculates a coordinate deviation from the component mounting target coordinates (step 42). .

  Here, the coordinate deviation means a deviation in the X, Y, and θ directions, but it is not always necessary to use all the values. Some of the deviations in the X, Y, and θ directions are measured and processed. Also good. Further, when a plurality of deviations in the X, Y, and θ directions are used, if it is determined that there is a possibility that even one of the parts is defective, the part is determined to be defective.

  After the measurement is completed, the substrate is carried out to the reflow unit 13 and the calculated coordinate deviation is output to the defect determination unit 15.

  Next, the reflow unit 13 applies heat to the board carried in from the post-mounting component position measuring unit 12 to perform soldering, and carries it out to the post-reflow component position measuring unit 14 (step 43).

  Next, the post-reflow component position measurement unit 14 performs imaging on the board carried in from the reflow unit 13, measures the component coordinates, and calculates a coordinate deviation from the component mounting target coordinates (step 44). After the measurement is completed, the substrate is carried out to a subsequent process, and the calculated coordinate deviation is output to the defect determination means 15.

  Next, the possibility of component failure is determined using the coordinate shift calculated in steps 42 and 44 (step 45).

  If it is determined that there is a possibility of component failure as a result of this determination, the possibility of component failure is notified to the outside (step 46).

  On the other hand, if it is determined that there is no possibility of component failure as a result of the determination, the process ends.

  Next, operations of the post-mounting part position measuring unit 12 and the post-reflow part position measuring unit 14 shown in FIG. 1 will be described with reference to FIGS.

  First, FIG. 5 shows an example of mounting the component 31 on the board in the component mounting means 11. The post-mounting component position measuring means 12 images the substrate, measures the component center position 34 from the obtained image, and calculates the coordinate deviation.

  Here, as a method of measuring the component center position 34, a method of detecting the component 31 from the captured image by template matching using the reference image of the component 31 and setting the center of the obtained region as the component center position 34. Alternatively, a method of obtaining the outer shape of the component 31 using the luminance change and setting the center of the obtained region as the component center position 34 can be considered, but the measurement is not limited to these methods.

  When the component center position 34 is measured, coordinate deviations Xm, Ym, θm are calculated from the difference of the component center position 34 with respect to the component mounting target coordinates, and the calculated values are output to the defect determination means 15.

  Here, since the component mounting target coordinates are generally the pad-to-pad center position 33 (the center position between the pads 32), the following description will be given assuming that the component mounting target coordinates are the pad-to-pad center position 33. .

  The post-reflow component position measurement unit 14 calculates coordinate deviations Xr, Yr, θr in the same manner as the post-mounting component position measurement unit 12, and outputs the calculated values to the defect determination unit 15.

  The defect determination means 15 determines the possibility of component failure from the coordinate deviations Xm, Ym, θm calculated by the post-mounting part position measurement means 12 and the coordinate deviations Xr, Yr, θr calculated by the post-reflow part position measurement means 14. To do. As a result of the determination, when the possibility of component failure is detected, the possibility of component failure is notified to the outside.

  Here, the determination method in the defect determination means 15 is shown below.

  When the solder is melted by the reflow means 13, the component 31 moves to a position where the interfacial tension between the two electrodes becomes equal. Therefore, if the product is a non-defective product, the component center position 34 is directed toward the inter-pad center position 33 that is the component mounting target coordinate. It is thought that moves.

  From this, comparing the coordinate deviation after component mounting and after reflow, if the coordinate deviation after reflow relative to the coordinate deviation after component mounting is in a direction away from the component mounting target coordinates, there is a possibility of a defect. Conceivable.

Next, FIG. 6 shows an example of soldering of the component 31 in the reflow means 13. Here, it is assumed that the state shown in FIG. In this case, when the coordinate deviations Xm, Ym, θm after component mounting and the coordinate deviations Xr, Yr, θr after reflow are compared,
Xr = (12/11) Xm
Yr = (2/9) Ym
θr = (1/6) θm
Since the signs of Xm and Xr are the same with respect to the X coordinate, that is, the direction of the deviation is the same and Xr> Xm, the X coordinate is moving away from the component mounting target coordinates, so a defect is possible. Judge that there is sex.

  Further, even when the component center position 34 moves in a direction approaching the component mounting target coordinates, that is, when the component center position 34 moves toward the component mounting target coordinates as viewed from the component center position 34 after the components are mounted, the coordinates after the components are mounted. The difference between the coordinate shift after mounting the component and the coordinate shift after reflow is larger than the shift, that is, if the movement amount after mounting the component after the reflow is larger than the coordinate shift amount after mounting the component, after the reflow process It has been considered that there is a possibility of a failure because it has moved to a position exceeding the component mounting target coordinates, that is, the component has moved more than necessary.

Next, FIG. 7 shows an example of soldering of the component 31 in the reflow means 13, which is different from FIG. Here, it is assumed that the state shown in FIG. In this case, when the coordinate deviations Xm, Ym, θm after component mounting and the coordinate deviations Xr, Yr, θr after reflow are compared,
Xr = (− 4/11) Xm
Yr = (2/9) Ym
θr = (1/6) θm
Thus, with respect to the X coordinate, since Xr <Xm, it can be seen that the X coordinate moves from the component center position 34 after component mounting toward the component mounting target coordinate. In addition, when | Xr−Xm |, which is the amount of movement from the state after component mounting to the state after reflow, is compared with the coordinate deviation amount | Xm | after component mounting, | Xr−Xm | Since the component center position 34 has moved to a position exceeding the component mounting target coordinates after the reflow process, it is determined that there is a possibility of a defect.

  Further, since the coordinate deviation after component mounting and the coordinate deviation after reflow are values with the component mounting target coordinates as the origin, if the respective signs are different, the component center position 34 is the component mounting target coordinates after the reflow process. It is also possible to determine that there is a possibility of a failure because it has moved to a position exceeding. In the example shown in FIG. 7, since the signs of Xm and Xr, which are deviation amounts in the X direction, are different, it is determined that there is a possibility of failure.

  However, in actuality, errors in measurement and variations in the stop position when the component 31 moves to a position where the interfacial tension acting on both electrodes are equal to each other occur. Therefore, the constant C1 is used to reflow from the state after the component is mounted. You may make it determine with a defect, when the movement amount to a later state is larger than C1 more than the amount of coordinate deviation after component mounting.

  Further, even when the component center position 34 moves in a direction approaching the component mounting target coordinates, the difference between the coordinate deviation Xm, Ym, θm after component mounting and the coordinate deviation Xr, Yr, θr after reflow is the difference after component mounting. If the value is smaller than the threshold value calculated from the coordinate deviation, the part 31 does not move much after the reflow process, that is, the self-alignment effect is small.

  Here, as the threshold value, it is conceivable to use a value obtained by multiplying the coordinate deviation Xm, Ym, θm after mounting the component by α (0 <α <1). It is conceivable that α is set according to the degree of self-alignment effect due to the material and the weight of the component. If the self-alignment effect is easy to work, if it is a non-defective product, the component center position 34 is likely to approach the component mounting target coordinates. Therefore, if the self-alignment effect is difficult to work, α = 1/3, and the self-alignment effect is easy to work. If the self-alignment effect is easy to work, such as α = 2/3, it is preferable to set α large.

  In addition, if the coordinate deviation Xm, Ym, θm after component mounting is small, the amount of movement is small even if it is a non-defective product. There is a possibility of determining that there is. For this reason, when the coordinate deviations Xm, Ym, and θm after component mounting are equal to or less than a certain value, it may be considered to use the constant C2 as the threshold value.

Next, FIG. 8 shows an example of soldering of the component 31 in the reflow means 13, which is different from FIGS. Here, it is assumed that the state shown in FIG. In this case, when the coordinate deviations Xm, Ym, θm after component mounting and the coordinate deviations Xr, Yr, θr after reflow are compared,
Xr = (7/11) Xm
Yr = (2/9) Ym
θr = (1/6) θm
Here, when α = 2/3, with respect to the X coordinate, since Xr <Xm and Xm−Xr is smaller than (2/3) Xm, the component center position 34 approaches the component mounting target coordinate. However, since the amount of movement is smaller than the threshold value, it is determined that there is a possibility of failure.

FIG. 9 shows an example of soldering of the component 31 in the reflow means 13, which is different from those shown in FIGS. Here, it is assumed that the state shown in FIG. In this case, when the coordinate deviations Xm, Ym, θm after component mounting and the coordinate deviations Xr, Yr, θr after reflow are compared,
Xr = (3/11) Xm
Yr = (2/9) Ym
θr = (1/6) θm
Therefore, since it does not apply to the condition for determining that there is a possibility of failure as described above, it is determined that there is no possibility of failure.

  In the examples shown in FIGS. 6, 7, 8, and 9, there is a possibility that all the conventional methods may be determined as non-defective products, whereas the method according to the present invention appropriately determines the possibility of defects. It is possible.

  As described above, according to the embodiment of the present invention, by determining the possibility of a defect from the coordinate deviation after component mounting and the coordinate deviation after reflow, the component floating or component electrode wetting with a small lift amount is determined. The possibility of a defect can be determined even when it has been difficult to determine the defect in the past, for example, the property is slightly inferior to a non-defective product.

  Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

For example, Rm (Rm = √ (Xm ² + Ym ² )) and Rr (Rr = √ (Xr ² + Yr ² )) regarding the coordinate deviation Xm, Ym, θm after component mounting and the coordinate deviation Xr, Yr, θr after reflow. ), The coordinate deviation in the X direction and the Y direction can be comprehensively compared as the coordinate deviation Rm, θm after component mounting and the coordinate deviation Rr, θr after reflow.

DESCRIPTION OF SYMBOLS 10 Solder printing means 11 Component mounting means 12 After mounting component position measuring means 13 Reflow means 14 After reflowing part position measuring means 15 Defect determination means 31 Parts 32 Pad 33 Pad center position 34 Component center position 100 Defect determination apparatus 101 Parts 102 Pad

Claims (10)

Printing solder on the board;
Mounting a component on the printed board of the solder;
Measuring component coordinates after mounting the component and calculating a first coordinate deviation from the component mounting target coordinates;
A reflow step of heating the substrate after mounting the component and soldering the component;
Measuring the component coordinates after the reflow, and calculating a second coordinate deviation from the component mounting target coordinates;
Determining a possibility of a defective part after the reflow based on the first coordinate shift and the second coordinate shift;
A defect determination method characterized by comprising:   The step of determining the possibility of the failure is to determine that there is a possibility of the failure when the second coordinate shift with respect to the first coordinate shift is in a direction away from the component mounting target coordinates. The defect determination method according to claim 1, wherein:   In the step of determining the possibility of the defect, the second coordinate shift with respect to the first coordinate shift is in a direction approaching the component mounting target coordinates, and the first coordinate shift is more than the first coordinate shift. 2. The defect determination method according to claim 1, wherein when there is a large difference between the coordinate deviation of the second coordinate deviation and the second coordinate deviation, it is determined that there is a possibility of the defect.   The step of determining the possibility of the failure is a direction in which the second coordinate deviation with respect to the first coordinate deviation approaches the component mounting target coordinates, and the first coordinate deviation and the second coordinate. The defect determination method according to claim 1, wherein it is determined that there is a possibility of the defect when a difference in deviation is smaller than a predetermined threshold value.   5. The defect determination method according to claim 1, wherein the first and second coordinate deviations are at least one of deviations in X, Y, and θ directions. A solder printing means for printing solder on a substrate; and
Component mounting means for mounting a component on the printed board of the solder;
A post-mounting component position measuring means for measuring the component coordinates after mounting the component and calculating a first coordinate deviation from the component mounting target coordinates;
Reflow means for heating the substrate after mounting the component and soldering the component;
A component position measuring unit after reflow that measures the component coordinates after the reflow and calculates a second coordinate deviation from the component mounting target coordinates;
A failure determination means for determining a possibility of a failure of the component after the reflow based on the first coordinate shift and the second coordinate shift;
A defect determination device characterized by comprising:   The defect determination means determines that there is a possibility of the defect when the second coordinate shift with respect to the first coordinate shift is in a direction away from the component mounting target coordinates. Item 7. The defect determination device according to Item 6.   The defect determination unit is configured such that the second coordinate shift with respect to the first coordinate shift is in a direction approaching the component mounting target coordinates, and the first coordinate shift and the first coordinate shift are greater than the first coordinate shift. The defect determination device according to claim 6, wherein when there is a large difference from the second coordinate shift, it is determined that there is a possibility of the defect.   The defect determination means has a direction in which the second coordinate deviation with respect to the first coordinate deviation approaches the component mounting target coordinates, and a difference between the first coordinate deviation and the second coordinate deviation is predetermined. The defect determination device according to claim 6, wherein if it is smaller than the threshold value, it is determined that there is a possibility of the defect.   10. The defect determination device according to claim 6, wherein the first and second coordinate shifts are at least one of shifts in the X, Y, and θ directions.

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