JPH0767036B2 - Electronic component mounting position correction method - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention is mainly applied to QFP (quad flat package), PLCC.
(Plastic leaded chip-carrier), SOP (small outli
ne pockage), SOJ (small-outline J-leaded packag
When mounting an electronic component that has multiple leads for surface mounting such as in e) on the substrate, the electronic component mounting position correction that enables the electronic component to be accurately positioned with respect to the component mounting position on the substrate It is about the method.

[Prior art]

Generally, when electronic components are automatically mounted on a board, the electronic components are sucked out by a suction device from a feeder that supplies the electronic components, and the electronic components are carried to the component mounting position set on the substrate and mounted. To do. When using a chip component for surface mounting with a large number of leads as an electronic component, the pitch between adjacent leads is small,
Even a slight misalignment leads to incorrect wiring. Therefore, to prevent miswiring, the position and orientation of the electronic component being conveyed is detected by the suction device, and the deviation between the position and orientation of the electronic component being conveyed is corrected according to the detected position and orientation. Then, it is considered to match the component mounting position. As a method of correcting the mounting position of such an electronic component, as disclosed in Japanese Patent Laid-Open No. 63-88896, it has been proposed to determine the orientation of the electronic component from the image of the lead of the electronic component.

[Problems to be Solved by the Invention]

The above method detects only two of the plurality of leads of the electronic component and uses them as the basis for the position correction calculation.
If the positions of the leads vary, the mounting position of the electronic component cannot be positioned with sufficiently high accuracy. Further, since only two leads are detected, it is not possible to detect even if the lead has a defect such as a bend or a bend. The present invention is intended to solve the above-mentioned problems, and the center coordinates of the tip edges of all the leads are averaged so as to accurately obtain the degree of positional deviation of electronic components, and the tips of all the leads. An object of the present invention is to provide a method for correcting the mounting position of an electronic component, which makes it possible to easily find a lead defect by obtaining the center coordinates of the edge.

[Means for Solving the Problems]

In the present invention, in order to achieve the above object, the center coordinates of the tip edge of each lead arranged in a substantially straight line on the image including the lead is obtained, and then with respect to the center coordinate of the tip edge of each lead. Apply the least-squares method to find the slope of a straight line passing through the center of the lead edge for each side of the package, and find the center position of the electronic component based on the center coordinates of the lead edge of each lead. The inclination of the electronic component with respect to the reference direction on the image is obtained based on the above, and the error in the center position of the electronic component with respect to the reference point on the image and the inclination are used as correction values. Further, the inclination of the electronic component with respect to the reference direction on the image may be obtained based on the distribution of the angles formed by the straight lines connecting the centers of the tip edges of the adjacent pairs of leads with respect to the reference direction of the image.

[Action]

According to the above method, in any method, since the correction value is a value obtained by averaging the variations in the center coordinates of the tip edges of all the leads, the error of the correction value becomes very small, Positioning to the component mounting position can be performed with high accuracy. Further, since the center coordinates of the leading edge are obtained for all the leads, it is possible to easily find defects such as bending and bending of the leads depending on the degree of variation in the center coordinates.

【Example】

As shown in FIG. 11, the electronic component 1 has a shape in which a plurality of leads 2 are projectingly provided on the periphery of a package 6, and the electronic device 1 is sucked by a suction device 3 and is fed or trayed at the position shown in FIG. 11 and the like, and is transported to the position shown in FIG. 11 and mounted at the component mounting position on the substrate 4. Further, the electronic component 1 is imaged by the image input device 5 such as a television camera at the position of the conveyance process by the suction device 3, and the position and orientation of the electronic component 1 are determined based on the image of the lead 2, and The position and orientation of the electronic component 1 are corrected so as to match the component mounting position according to the position and orientation. A method of detecting the position and orientation of the electronic component 1 based on the image of the lead 2 will be described below. The image obtained by the image input device 5 is processed so that the outline of the lead 2 and the background can be clearly identified by devising the illumination of the electronic component 1 or by performing image processing. Thus, since the image aligned with the plurality of leads 2 ₁ to 2 _n as shown in Figure 3 is obtained, a plurality of the reference direction is set so as to intersect the projecting direction of the lead 2 ₁ to 2 _n The search lines la to le are set, and the intersections of the search start lines SL and the search lines la to le virtually set to be orthogonal to the reference direction are set as the search start points p _{1 to} p ₅ and the search lines la to Search on le. That is, assuming that the X direction of the image is the reference direction, a plurality of search lines la to le are set at equal intervals in the Y direction, and the same X coordinate is provided near the left ends of these search lines la to le. The search starting points p _{1 to} p ₅ can be set. Here, the interval between each search line la~le in the Y-direction is set smaller than the projection length of the lead 2 ₁ to 2 _n. As described above, when searching each search line la to le from the left end,
Since the intersection with the edges of leads 2 _{1 to} 2 _n is detected, the distance from the search start points p _{1 to} p ₅ to the intersection is the shortest lead 2 ₁
Is regarded as the leftmost lead 2 ₁ . Then, starting from the left end of the lead 2 _1, sequentially obtains the end position of each lead 2 ₁ to 2 _n. End position of each lead 2 ₁ to 2 _n are respectively obtained as follows. First, the leftmost lead 2 ₁
For, since the search line li intersecting left end of the lead 2 ₁ by the search on the search line la~le is known, the search starting point based on the coordinates of the intersection of the search line li to the lead 2 ₁ Is set, and a search line l ₁ running in the X direction is set. In addition, from this search start point in the Y direction
The search start point having the same X coordinate as the search start point is set apart from Dy, and the search line l ₂ running in the X direction is set. Here, the distance Dy in the Y direction between both search lines l ₁ and l ₂ is
It is set sufficiently smaller than the projection length of the lead 2 _1. Furthermore, both search start point is determined to be located to the left than the lead 2 _1. That is, the inclination of the electronic component 1 taken out by the suction device 3 is within a range of ± 30 °, and the range of the positional deviation in the protruding direction of the lead 2 is known. Therefore, the search is performed based on these conditions. When the search start points of the lines l ₁ and l ₂ are set, both search lines l ₁ and l ₂ intersect with the lead 2 ₁ and the X coordinate of the search start point is located on the left side of the lead 2 _1. The search start point is set so that When the search is started on each of the search lines l ₁ and l ₂ set as above from each search start point, each search start point and the lead
The distance to the intersection of 2 ₁ is obtained. Next, the difference between the two distances is set to D ₁ , and a search line running in the X direction with a point separated by D _{1 in} the X direction and Dy in the Y direction from the search start point of the search line l ₂ as the next search start point. Set l ₃ . In this way, the search line l ₃ is searched for the intersection with the lead 2 ₁ and the search line
For l ₃ , find the distance from the search start point to the intersection. Here, the difference in distance between the search start point and the intersection point on the search lines l ₂ and l ₃ is D _2, and a point separated from the search start point on the search line l ₃ by D _{2 in} the X direction and Dy in the Y direction. Set as the starting point for the next search. The above procedure is repeated to sequentially set the search lines l _{1 to} l _n . The X coordinate of the search start point is sequentially shifted as described above, as shown in FIG. 4 (b).
Against Unless Ika shifting the X coordinate of the search starting point when the read 2 ₁ is inclined, overlapping search start point to the lead 2 _1, that the intersection of the lead 2 ₁ after the search start is not Motomara Because there is. When sequentially repeating the above operations, the search line l _n will be set to a position beyond the distal end of lead 2 ₁ soon. The length of the search lines l _{1 to} l _n is the lead
Since 2 based on the _first width is set to a predetermined value, unless intersect the lead 2 ₁ within the scope of this length, it can be seen that beyond the distal end of the lead 2 _1. If a search line l _n that does not intersect lead 2 ₁ is obtained,
As shown, the center value of the search line l _n search starting point before a Y coordinate of the search line l _n-1 Y coordinate of search start point and Y coordinates, the search line l _n Same as search start point X
Set a search line l _b with a search start point with coordinates. If the search line l _b is them crosses the lead 2 _1, set the following search line l _bb in the center of the further search line l _n,
If intersect the lead 2 _1, the center of the search line l _n-1 sets the next search line l _bb. In this way, search lines are set one after another between the newly drawn search line and the previous search line, and this is continued until the resolution of the image reaches the limit. Here, the X coordinate of the search start point of each search line l _b , l _bb , ..., L _t is the same as the X coordinate of the search start point of the search line l _n . Such procedure finally obtained search line l _t can be regarded as passing the tip of the lead 2 _1. In the following description, this method is called a binary search. According to 2 minutes exploration time of detecting the tip of the lead 2 ₁ is substantially constant, and it can be detected at high speed. Meanwhile, search line l _i a plurality of intersecting the lead 2 ₁ of the search line l ₁ to l _n described above, the l _j, as shown in Figure 6, the intersection of the ends of the leads 2 ₁ in the width direction Midpoint
Find C _i and C _j . Intersection C of these midpoints C _i, and the straight line passing through the C _j, the search line l _t through the tip of the lead 2 _1, leads 2 ₁
To the extent that can be regarded as the leading edge of the midpoint, it is close to the midpoint of the lead 2 ₁ of leading edge. Therefore, by defining the point of intersection C with the middle point of the lead 2 ₁ of leading edge, obtaining an intersection C of coordinates (X _1, Y _1). In the above procedure, with regard leftmost lead 2 ₁ is the coordinate of the midpoint of the leading edge is determined. When the coordinates of the midpoint of the leading edge of the leftmost lead 2 ₁ are obtained, this time, the midpoint of the leading edge of the _second lead 2 ₂ from the left is obtained. The first search line l ₁₁ for the second lead 2 ₂ is the leftmost lead 2 ₁ and 2 as shown in FIG.
It is set to have intersection points s ₁ and s ₂ both with the second lead 2 ₂ . That is, it is empirically known that the inclination of the leads 2 is within the predetermined range as described above, and it is known that the pitch between the leads 2 is 0.5 to 1.27 mm. Based on the search line
The search start point and length of l ₁₁ are set. On the search line l ₁₁ , the coordinates of the intersections s ₁ and s ₂ and the search line l ₁₁
The width of the leads 2 ₁ and 2 ₂ above is obtained. The basis of the intersection s ₂ thus obtained, carries out the search by setting a plurality of search line at predetermined intervals Dy in the Y direction using the same method as the case of the left end of the lead 2 _1, then 2 minutes search Go to find the coordinates (X ₂ , Y ₂ ) of the midpoint of the tip edge of the _second lead 2 ₂ . A search line l ₃₁ separated from the search line l ₁₁ by a distance equal to the difference Da between the Y coordinates Y ₁ and Y ₂ of the midpoints of the tips of the leads 2 ₁ and 2 ₂ obtained as described above is set, This search line l ₃₁
And find the intersection s _{3 of the third} lead 23. The search start point of the X coordinate of this search line l ₃₁ is a position that does not overlap the lead 2 ₃ based on the inclination of the leads 2, the pitch between the leads _{2 and} the width of the lead 2 ₂ obtained on the search line l _11. Is set. The intersection s ₃ as a reference to determine the using the same technique as the left end of the lead 2 ₁ 3 th lead 2 ₃ tip edge of the midpoint of the coordinates (X _3, Y _3). In the subsequent processing, the width of the lead 2 is the search line l ₃₁ set for the _third lead 2 ₃ .
The same value is used as when the search starting point of was found. This time the middle point of the tip edge of the _second lead 2 ₂ and the third lead
A search line l _41, which is separated from the search line l _{31 in the} Y direction by a distance equal to the difference Db in Y coordinate from the midpoint of the leading edge of 2 ₃ , is set, and this search line l ₄₁ and the fourth lead 2 ₄ are set. Find the intersection of. Do the same for all leads in the image 2 ₁ ~
Find the coordinates (X _i , Y _i ) of the midpoint of the leading edge of 2 _n . Further, depending on the type of the electronic component 1, if the leads 2 are provided only on the two sides of the package 6, the same processing is performed on the two sides, and if the leads 2 are provided on the four sides of the package 6, the same processing is performed. The processing up to this point is shown in FIG. As described above, the coordinates of the midpoint of the leading edge of each lead _{2 i (X i, Y i} ) when seeking, the left end of the lead 2 ₁ tip edge center and the second lead 2 ₂ leading edge Difference of Y coordinate from the center of
Compared to Y _{1 to} Y ₂ (= Da), other adjacent leads 2 _i-1 , 2 _i
Of If the difference Y _i-1 to Y _i of Y coordinate becomes larger than the prescribed value, since it can be determined that broken or bent leads 2 of the electronic component 1 of the currently transport is occurring, the electronic component 1 It is determined that the product is defective, the process is performed, and the subsequent calculation is not performed. If the product is not determined to be defective, the subsequent calculation is performed. First, the least squares method is applied to the coordinates of the midpoint of the leading edge of the leads 2 arranged on each side of the package 6, and a linear function representing the inclination of the leading edge of the lead 2 is obtained. In addition, the angles of the obtained straight lines with respect to the X axis and the Y axis are obtained. As described above, when the linear function representing the inclination of the leading edge of the lead 2 is obtained for each side, the variation in the protrusion amount of the lead 2 is averaged. Next, as shown in FIG. 8, intersections A (Xa, Ya) to D (Xd, Yd) of the linear functions on a pair of adjacent sides of the package 6 and the X-axis and Y-axis of each linear function. The inclinations θa to θd with respect to are obtained. Further, an intersection point O ′ (X ₀ ′, Y ₀ ′) of a straight line connecting the points A and C and a straight line connecting the points B and D is obtained, and the center O (X _{0 0} of the component mounting position defined on the screen is obtained. , Y ₀ ) (ΔX = X ₀ ~ X
₀ by obtaining a _{', ΔY = Y 0 ~Y 0} '), it is possible to obtain a correction value related to the position deviation between the center position of the center and part reality position of the electronic component 1. Further, the average value Δθ = (θa + θb + θc + θd) / 4 of the angles θa to θd can be used as the correction value for the rotational deviation of the electronic component 1. When the leads 2 are provided only on two sides of the package 6, the center O ′ of the electronic component 1 can be obtained by obtaining the center of gravity of the center coordinates of the tip edges of the leads 2. Regarding the inclination, a linear function may be obtained for each side by the method described above, and the average value of the inclination angles of both linear functions with respect to the reference axis of the screen may be obtained. In the above embodiment, to determine the inclination of the electronic component 1 by applying the least squares method to the coordinates of the center of the lead 2 leading edge, as shown in FIG. 9, each adjacent pair of leads 2 ₁ to 2 _{For n} , the correction value of the rotation deviation of the electronic component 1 is calculated by obtaining the angles θ ₁₂ , θ ₂₃ , ... θ _{(n-1) n} with respect to the X axis or the Y axis of the straight line connecting the midpoints of the leading edges. You may do it. In this case, if you take the angle in a predetermined unit (for example,
As shown in FIG. 10, the angle distribution is close to the normal distribution. Therefore, if the peak value of the distribution is obtained based on the standard deviation of this distribution, the rotation deviation of the electronic component 1 A correction value Δθ is obtained. If there is a lead 2 whose angle deviates from the specified range with respect to the correction value Δθ, the electronic component 1 is determined to be defective and the process is performed, and the subsequent calculation is not performed. To do so. Electronic component 1
The correction values (ΔX, ΔY) for the displacement of the center position of are
It may be obtained in the same manner as in the above embodiment. As described above, when the correction value of the rotation deviation is obtained from the angle distribution, the defect determination can be performed again after the defect determination of the electronic component 1 due to the variation in the protrusion amount of the lead 2, so that the defective product can be reliably extracted. It is possible. The above procedure is shown in FIG. In each of the above-mentioned embodiments, the coordinates of the center of the tip edge are obtained for all the leads 2, but if the pitch between the leads 2 is relatively large and the accuracy may be lowered to a certain extent, one The center coordinates of the tip edge of the lead 2 may be obtained every two or two.

【The invention's effect】

As described above, the present invention obtains the center coordinates of the tip edges of the leads arranged in a substantially straight line on the image including the leads,
Next, the least squares method is applied to the center coordinates of the lead edge of each lead to obtain the slope of a straight line passing through the center of the lead edge of each lead for each side of the package. The center position of the electronic component is obtained based on the above, the inclination of the electronic component with respect to the reference direction on the image is obtained based on each of the straight lines, and the error in the center position of the electronic component with respect to the reference point on the image and the inclination are used as correction values. Since the correction value is a value obtained by averaging the variations in the center coordinates of the tip edges of all leads, the error in the correction value becomes extremely small, and This has the advantage that the positioning can be performed with high accuracy. Further, since the center coordinates of the leading edge are obtained for all the leads, there is an advantage that defects such as bending and bending of the leads can be easily found depending on the degree of variation of the center coordinates. Furthermore, the tilt of the electronic component with respect to the reference direction on the image is
The same effect can be obtained even if it is determined based on the distribution of the angles formed by the straight lines connecting the centers of the tip edges of the pairs of adjacent leads to the reference direction of the image.

[Brief description of drawings]

FIG. 1 is an operation explanatory view showing a processing procedure in an embodiment of the present invention, FIG. 2 is an operation explanatory view showing a procedure for detecting the center coordinates of the leading edge of the lead in the same as above, and FIG. 4 is an operation explanatory diagram showing an example of setting a search line for detecting a lead, and FIG. 4 (a) is an operation explanatory diagram showing an example of setting a search line when roughly detecting the tip of the lead in the same as above; FIG. 5B is an operation explanatory view showing a problem caused by a search line having a setting different from that shown in FIG. 5A, and FIG. 5 is a search in the dichotomizing search for obtaining the leading edge of the lead in the same as above. FIG. 6 is an operation explanatory view showing an example of line setting, FIG. 6 is an operation explanatory view showing the concept of the method of obtaining the center coordinates of the leading edge of the lead in the same as above, and FIG. Show the concept of how to set FIG. 8 is an operation explanatory view showing a method for obtaining a correction value for rotational movement and parallel movement of the electronic component in the same as above, and FIG. 9 is rotational movement of the electronic component from the center coordinates of the tip edge of the lead in the same as above. Fig. 10 is an explanatory view of the method for obtaining
Explanatory diagram showing an example of the angle distribution when using the method of the figure,
FIG. 11 is a schematic configuration diagram showing a mounting process of the electronic component in the present invention. 1 ...... electronic component, 2, 2 ₁ to 2 _n ...... lead, 3 ...... adsorber, 4 ...... substrate, 5 ...... image input device, 6 ...... package.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-271500 (JP, A) JP-A-63-88896 (JP, A) JP-A-63-75503 (JP, A)

Claims (2)

[Claims] 1. An electronic component having a plurality of leads protruding from the periphery of a package is picked up by an image input device in the process of being conveyed to a component mounting position of a circuit board, and the component mounting position is determined based on the image of the lead. In a method for correcting the mounting position of an electronic component that corrects the deviation between the position and the orientation of the electronic component, the center coordinates of the leading edge of each lead arranged in a substantially straight line on the image are obtained, and then the center of the leading edge of each lead is determined. The least squares method is applied to the coordinates to find the slope of the straight line passing through the center of the lead edge for each side of the package, and the center position of the electronic component is calculated based on the center coordinates of the lead edge of each lead. The inclination of the electronic component with respect to the reference direction on the image is obtained based on each of the straight lines, and the error in the center position of the electronic component with respect to the reference point in the image and the inclination are used as correction values. Mounting position correcting method of the electronic component to symptoms. 2. An electronic component having a plurality of leads protruding from the periphery of a package is picked up by an image input device in the process of being conveyed to a component mounting position of a circuit board, and the component mounting position is detected based on the image of the lead. In a method for correcting the mounting position of an electronic component that corrects the deviation between the position and the orientation of the electronic component, the center coordinates of the leading edge of each lead arranged in a substantially straight line on the image are obtained, and then the center of the leading edge of each lead is determined. The center position of the electronic component is determined based on the coordinates, and the electronic component with respect to the reference direction on the image is based on the distribution of the angle formed by the straight lines connecting the centers of the tips of the adjacent pairs of leads with respect to the reference direction of the image. Of the center position of the electronic component with respect to the reference point on the image and the inclination are used as the correction values.