JP2001127498A - Method and system for detecting lifting of lead - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly detect lifting of leads and detect lifting of leads in a short computing time, when an electronic component is mounted. SOLUTION: An electronic component 2, sucked by a suction nozzle 8, is positioned above a laser device 9, and the height of leads is detected by irradiating the leads of the electronic components with laser light from the laser device 9. Two lowest leads are extracted from each of the rows of leads A-D and a virtual plane, including the extracted two points a1 and a2 of the lead row and one point c1 of the opposed lead row, is calculated for each lead row, and the amount of distance of the lead from the calculated virtual plane is found. In this constitution, an effective virtual plane can be found more efficiently than through simple extracting of three points from multiple leads for finding a virtual plane, the errors in height based on the machine error can be suppressed, and lifting of the leads can be detected accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting lead floating of an electronic component, and more particularly, to irradiating a laser beam from a laser device toward a lead of an electronic component to calculate a virtual plane including the lead. The present invention also relates to a method and an apparatus for detecting lead lift of an electronic component for detecting the lift of each lead with respect to this virtual plane.

[0002]

2. Description of the Related Art Conventionally, in an electronic component mounting apparatus, an electronic component supplied from a component supply unit is sucked by a suction nozzle of a transfer head, and the transfer head is moved onto a printed circuit board to transfer the electronic component to the substrate. It is mounted on the upper predetermined position. In this case, since the electronic component is not necessarily sucked in a correct posture, the electronic device is imaged by the imaging device, and the image is processed to obtain the positioning data of the component. Also,
When mounting electronic components such as narrow lead pitch and narrow lead width QFPs and connectors, if the leads have floating, the leads cannot be bonded to the electrodes of the substrate. It is known to detect the floating of a lead by irradiating a laser beam toward the lead, calculating a virtual plane including the lead, and calculating the floating amount of each lead with respect to this virtual plane (for example, And JP-B-7-94976).

[0003] Specifically, as shown in FIG.
The laser device 103 irradiates a laser beam toward the lead 102 of the electronic component 101 adsorbed at 00 and determines the heights Z1, Z2,... Of the respective leads 102 from the reference plane S, thereby lifting the leads 102. Has been detected.

[0004]

The causes of the lead lift include bending error of the lead, tilt error 軸 θ1 of the axis of the nozzle, tilt error △ θ2 of the lower surface of the nozzle for sucking electronic components, and the like. Further, there are a tilt error of the upper surface of the mold body of the electronic component and a position error of the XY table for moving the transfer head in the XY directions. If there is such a mechanical error, the electronic component 101 is inclined at an angle △ θ with respect to the horizontal plane L, and a height error of △ Z occurs, and there is a problem that the floating of the lead 102 is erroneously determined.

There is also a method in which three leads are arbitrarily selected, and a plane formed by these three points is defined as a virtual plane, and the vertical difference of each lead with respect to this virtual plane is obtained. However, since the virtual plane is not an actual mounting surface, However, there is a problem that a large error occurs in a state where the electronic components are actually arranged on the plane.
A method of calculating a virtual plane by calculating all other combinations of leads is also conceivable, but the calculation time becomes enormous and poses a practical problem.

Accordingly, the present invention eliminates the mechanical errors as described above, and can accurately detect the floating of the lead and detect the floating of the lead when the electronic component is actually mounted in a short calculation time. An object of the present invention is to provide a method and an apparatus for detecting a floating lead of an electronic component, which can perform the method.

[0007]

According to the present invention, an electronic component is positioned above a laser device while the electronic component is being attracted to a nozzle of a transfer head and is transferred to a substrate. By irradiating a laser beam toward the lead, the height of three points of the lead is detected, and then a virtual plane including the three points is calculated, and the floating amount of each lead with respect to this virtual plane is obtained. In each of the lead rows, the lowest lead is extracted by two points, and two points of the extracted lead and one point of the lowest lead in the lead row opposite to the lead row having these two points are extracted. It is characterized in that a virtual plane including each is calculated for each lead row, and a lead floating amount is calculated for each calculated virtual plane (first characteristic).

According to the present invention, in the case of an electronic component having lead rows on four sides, the lowest lead among the lead rows is extracted for each of the four lead rows, and the extracted 4 leads are extracted. It is also characterized in that a virtual plane formed by selecting three points among the points is calculated, and the lead floating amount is calculated for each calculated virtual plane (second characteristic).

In the present invention, a virtual plane having the first and second features and including the extracted three points is calculated,
Among the triangles formed by the three points, a virtual plane is selected from among the triangles in which the center of gravity of the electronic component is located among the triangles such that the virtual plane associated with the triangle is lower than each lead. It is also characterized in that the distance from each virtual plane to the lead is defined as a lead floating amount, and the lead floating is detected by comparing with a preset lead floating allowable amount.

In any of the inventions, compared to simply extracting three points from a large number of leads to obtain a virtual plane,
Effective virtual planes can be found efficiently and the amount of floating of each lead with respect to this virtual plane is determined, eliminating height errors based on mechanical errors and accurately detecting the floating of each lead. can do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings.

FIG. 1 is a mounting process diagram of an electronic component mounting apparatus for mounting an electronic component on a printed circuit board. The electronic component mounting apparatus mounts an electronic component having a narrow lead pitch through a series of processes. In the step shown in FIG. 1A, the electronic component 2 stored in the tray 1 is picked up by the suction nozzle 8 attached to the transfer head 7 of the mounting apparatus. In the step shown in FIG. 1B, an image of the sucked electronic component 2 is captured by the positioning camera 6, and is positioned by using the image processing device 4, and the positioning information is obtained. Then, while moving to the next step, the electronic component is rotated and the angle is corrected so that the extending direction of the lead is correctly oriented in the XY directions.

In the step shown in FIG. 1C, the electronic component 2 is transferred above the laser device 9 using the positioning information obtained in the step shown in FIG. 1B, and the transfer head 7 is moved in the X and Y directions. The laser beam is irradiated to each lead of the electronic component 2 while moving the lead to measure the lead height. Then, a lead floating detection process is performed, and if there is no abnormality in the result, FIG.
In the step shown in FIG. 1D, a correction calculation of the printed board 3 and the mounted electronic component 2 is performed based on the positioning information obtained in the step of FIG. Attach in position.

In such component mounting, if the lead of the electronic component has a lift, the lead cannot be bonded to the electrode portion of the substrate.
As shown in (C), while the electronic component is attracted to the nozzle of the transfer head and is transferred to the substrate, the electronic component is positioned above the laser device, and is directed from the laser device to the lead of the electronic component. By irradiating a laser beam, the height of three points on the lead is detected, and then a virtual plane including the three points is calculated, and the floating amount of each lead with respect to this virtual plane is detected. .

[0015] Japan Electronic Machinery Manufacturers Association Standard EIAJ ED-
7401-4, the uniformity of the lowermost surface of the terminal is defined as follows.

The variation in the vertical distance from the mounting surface (virtual plane) to the lowest point of all the terminals is called the uniformity of the terminal lowermost surface, and the distance from the farthest terminal to the lowest point is called the uniformity. , Y Definition of the virtual plane Of the geometric planes passing through the lowest points of any three terminals,
A plane in which the lowest points of the other terminals are all present on the package body side is called a virtual plane. However, the center of gravity of the package must be included inside or on the side of the triangle formed by the three points. However, it is not affected by its own weight. Therefore, the virtual plane cannot be obtained by simply extracting three points from many leads. Therefore, the present invention is to efficiently find a virtual plane, eliminate a height error based on a mechanical error, and obtain a floating amount of each lead with respect to the virtual plane, and it will be described in detail below. I do.

FIG. 2 shows how the lift (error in the Z direction) of the lead 2a of the electronic component 2 is measured. 2
b is a molded body of the electronic component, and the lead 2a
Are extended to four sides. The laser device 9 has a light receiving unit 12 on a side of the light emitting unit 10. The lead 2a is formed by punching a lead frame or a film carrier. Now, the electronic component 2 is positioned above the laser device 9, and the lead 2 a is irradiated with laser light while the transfer head 7 is horizontally moved in the XY directions, and the reflected light is received by the light receiving unit 12. Thus, the height Zi of each lead 2a from the reference plane S is detected.

An example of the flow of the lead floating detection operation for one electronic component 2 and the processing operation of the fetched data will be described with reference to FIGS. 3 and 4. FIG.

First, in step S10, information on electronic components is received from the component mounting control unit. For example, it is information such as QFP or terminal pitch and arrangement. Step S1
In step 1, the LED lighting is turned on, a two-dimensional image of the bottom surface of the electronic component 2 is captured, and the LED lighting is turned off.

Next, in step S12, a terminal arrangement calculation process of the electronic component 2 from which the image is taken is performed. There are various methods (algorithms) in this calculation process, but a typical one will be described here. First, the inclination of the lead on one side of the rectangular electronic component 2 such as QFP is roughly detected. Next, the positions of two leads arbitrarily selected from the detected leads are roughly detected. Finally, the lead position is accurately detected based on the roughly detected lead position. In this way, if the position of a lead on one side of a quadrangular component such as a QFP is detected, the lead position on the other side may be accurately detected based on this lead position. . Then, the position of the center of gravity in the terminal arrangement of the electronic component 2 is obtained from the detected lead position.

Next, in step S13, step S12
Is compared with the electronic component information received in step S10 to determine whether the lead pitch is appropriate.
If not, a terminal arrangement error is output in step S27. On the other hand, if appropriate, the electronic component inspection result such as the position of the center of gravity of the terminal arrangement and the inclination (angle) of the terminal arrangement is transmitted to the component mounting controller in step S14. The component mounting control unit rotates the nozzle that is holding the electronic component 2 so that the terminal arrangement becomes X.
The angle of the electronic component 2 is corrected so as to correctly face the Y direction. Since the terminal position is known by the terminal arrangement calculation process, the electronic component 2 is moved XY in step S15, and a laser beam is emitted to a required terminal position to measure the height of the lead.

In step S16, an approximate straight line is obtained for each lead row. Multiple linear regression

[0023]

(Equation 1)

Since a more linear expression is obtained,

[0025]

(Equation 2)

It is sufficient to obtain ab more.

In FIG. 5, assuming that the horizontal direction is X, the vertical direction is Y, and the height direction is Z, the approximate expression for obtaining the lead arrays A and C is a + by = z, and the approximate expression for obtaining the lead arrays B and D is Is a + bx = z.

A straight line passing through each lead height is drawn with the inclination of the approximate straight line obtained in step S17, and two leads with the minimum Z-axis intercept are extracted. In the example of FIG.
A1 and a2 in lead row A, b1 and b in lead row B
2. In the lead row C, c1 and c2 are shown, and in the lead row D, d1 and d2 are extracted with the minimum intercept.

In the following, a triangle composed of three leads is extracted. Extracting a triangle from the combination of the eight leads leads to a large number of combinations and a long calculation time. Therefore, in the present embodiment, triangles are extracted by processes that are divided into two typical cases, that is, a case where two points of a triangle exist in one lead row and a case where one point of a triangle exists in one lead row. It shall be.

In step S18, a triangle composed of three leads is extracted. First, as shown in FIG. 5A, the process starts from a case where one side of the triangle is in the lead row. Lead row A
Is selected, and a1 and a2 obtained in step S17 are adopted. Next, a lead row C opposite to the lead row A is selected, and c is selected from c1 and c2 obtained in step S17.
1 to form a triangle a1a2c1. If the center of gravity G of the electronic component is not located in the triangle thus formed, this triangle is not extracted.

In step S19, one side of the triangle closest to the center of gravity G of the electronic component 2 is extracted. A short side of a perpendicular drawn from the center of gravity G to each side of the triangle is selected. In step S20, a straight line parallel to the one side extracted in step S19 and passing through the center of gravity G is determined, and the intersection of this straight line and the other two sides of the triangle is determined.

In step S21, it is determined whether or not the intersection obtained in step S20 is within a specified range. Each data has three-dimensional data such as a1 (l, m, n). X of the data in the lead row A has the same positive value, and X of the data in the lead row C has the same negative value. In addition, Y of the data in the lead row B has the same positive value, and Y of the data in the lead row D has the same negative value. The range of the values of X and Y forms the above specified range. If it is within the specified range, the process proceeds to the next step. If it is out of the specified range, the process returns to step S18.
Extract another triangle. For example, next select lead row B,
This is a triangle composed of two points b1b2 and one lower point of d1d2.

If it is determined in step S21 that the extracted triangle is within the specified range, then in step S22, a formula for a plane formed by the triangle is obtained. That is, a virtual plane is calculated. The height Zo of the virtual plane K with respect to the reference plane S (FIG. 2) can be easily calculated from the plane equation a + bX + cY = Z.

Next, in step S23, a height difference between all the lead heights detected in advance and the height Zo of the virtual plane K is determined. That is, if the height of each lead is Zi, △
Find Z = Zi-Zo. Subsequently, in step S24, it is determined whether the height of each lead is all above the virtual plane. If the value of ΔZ obtained in step S23 is plus, the height of the lead is above the virtual plane, and if it is minus, it is below. If there is a negative ΔZ, the process returns to step S18 to extract the next triangle.

In step S25, the maximum value of ΔZ obtained in step S24 is extracted and stored in a memory. In step S26, it is determined whether or not triangles have been extracted for all lead rows.

In the following step S28, the lower one of the data extracted two points from each lead row is selected.
In the example of FIG. 5B, a1, b2, c1, and d1 are selected. A step S29 extracts a triangle composed of the four points selected in the step S28. For example, FIG.
This is a triangle composed of a1b2c1 shown in (B).

Steps S30 to S37 are the same procedures as steps S19 to S26 described above, and therefore will not be described.

In step S38, steps S25 and S3
The largest value among the ΔZ stored in step 6 is adopted as the lead floating amount. A step S39 compares the lead floating amount adopted in the step S38 with a predetermined threshold value. If it is equal to or greater than the threshold value, a read floating error is determined in step S40. If a lead floating error is detected, the mounting of the electronic component 2 on the board 3 is stopped.

In the above embodiment, the electronic component has leads extending in all directions like QFP. However, the present invention is not limited to this. The present invention can also be applied to lead lift inspection of electronic components.

[0040]

As described above, according to the present invention, the electronic component is positioned above the laser device during the transfer of the electronic component to the substrate by attracting the electronic component to the nozzle of the transfer head. The height of the lead is measured by irradiating a laser beam toward the lead of the electronic component, and then a virtual plane serving as a mounting surface of the electronic component is calculated, and the floating amount of each lead with respect to this virtual plane is obtained. .
In this case, in the present invention, simply three out of many leads is used.
Compared to extracting a point and finding a virtual plane, it is possible to efficiently find an effective virtual plane, so that the bending deformation of the lead, the inclination error of the nozzle axis, and the lower surface of the nozzle that sucks electronic components Tilt error, tilt error of the upper surface of the electronic component mold body, X for moving the transfer head in the XY directions
It is possible to easily and quickly find the lead floating caused by various causes such as a position error of the Y table. Moreover,
While the electronic component is attracted to the nozzle of the transfer head and transferred to the substrate, that is, during the operation of mounting the electronic component on the substrate, the floating of the lead can be detected, so it is necessary to mount the electronic component on the substrate. Tact time can be significantly reduced, and electronic components can be mounted on a board at high speed and high efficiency.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a flow of mounting an electronic component.

FIG. 2 is a configuration diagram showing a configuration for detecting a height of a lead of an electronic component.

FIG. 3 is a flowchart showing a flow of detecting lead floating.

FIG. 4 is a flowchart showing a flow of detecting lead floating.

FIG. 5 is an explanatory diagram showing a process of calculating a virtual plane.

FIG. 6 is an explanatory diagram showing lead floating based on a mechanical error.

[Explanation of symbols]

 2 Electronic components 3 Printed circuit board 8 Suction nozzle 9 Laser device

Claims (10)

[Claims] 1. A method for inspecting lead floating of an electronic component comprising a plurality of lead rows in which a plurality of leads extending outward from a main body part are arranged in a line, wherein the electronic component is attracted to a nozzle of a transfer head. During the transfer to the substrate, the electronic component is positioned above the laser device, and the laser device emits laser light from below toward the leads of the electronic component to detect the height of the leads. Two points of the lowest lead are extracted for each row, and a virtual plane including two points of the extracted lead and one point of the lowest lead in the lead row opposite to the lead row having these two points is defined as: For each lead row, calculate the distance from each virtual plane to the lead for each calculated virtual plane as the lead floating amount, and compare with the preset lead floating allowable amount to determine the lead floating amount. Lead floating detection method of the electronic component, characterized in that the. 2. A virtual plane in which a virtual plane associated with the triangle is located lower than each lead from triangles in which the center of gravity of the electronic component is located among the triangles among the three triangles, In the case of an electronic component having lead rows on four sides, the lowest lead in each lead row is extracted for each of the four lead rows, and a virtual plane including three of the extracted four points. Is selected from among the triangles formed by the three points, from among the triangles in which the center of gravity of the electronic component is located in the triangle, the virtual plane associated with the triangle is located lower than each lead. 2. The method according to claim 1, further comprising the steps of: 3. To determine whether the center of gravity of the electronic component is a triangle located in the extracted triangle, extract one side of the triangle closest to the center of gravity and pass through the center of gravity in parallel with the one side. 3. The method according to claim 2, further comprising: determining whether a virtual plane associated with the triangle is positioned lower than each lead only when the straight line intersects the other two sides of the triangle within a predetermined range of XY coordinates. 4. A method for detecting lead floating of an electronic component according to claim 1. 4. An approximate straight line related to the lead height is calculated for each lead row, and two leads having the lowest Z-axis (height direction) intercept of a straight line passing through each lead height with an inclination of the approximate straight line are determined. 2. The method according to claim 1, further comprising extracting the lead floating of the electronic component. 5. A method of detecting lead floating of an electronic component having a plurality of leads arranged on one side and a plurality of leads extending outward from a main body, wherein the electronic component is attracted to a nozzle of a transfer head. During the transfer to the substrate, the electronic component is positioned above the laser device, and the height of the lead is detected by irradiating laser light from below toward the lead of the electronic component from the laser device. The lowest lead among the lead rows is extracted for each of the four lead rows, and a virtual plane formed by selecting three of the extracted four points is calculated. A lead floating detection method for an electronic component, wherein a lead floating amount is obtained. 6. A lead floating detection device for an electronic component, comprising a plurality of lead rows in which a plurality of leads extending outward from a main body part are arranged in a line, wherein the electronic component sucked by a nozzle of a transfer head is provided. A laser device arranged below, a means for irradiating a laser beam from below toward the leads of the electronic component from the laser device to detect the height of the leads, and two points each having the lowest lead for each lead row Means for extracting two points of the extracted leads, and means for calculating a virtual plane including three points of one point of the lowest lead in the lead row opposite to the lead row having the two points for each lead row Means for calculating a lead floating amount by setting a distance from each virtual plane to the lead to the calculated virtual plane as a lead floating amount and comparing the lead floating amount with a preset lead floating allowable amount. To be Lead lift detection device for electronic components. 7. A means for selecting, from among the triangles composed of the three points, a virtual plane whose center of gravity of the electronic component is located within the triangle, such that a virtual plane associated with the triangle is located lower than each lead. In the case of an electronic component having a lead array on four sides, means for extracting one point of the lowest lead in each lead array for each of the four lead arrays, and three points of the extracted four points Means for calculating virtual planes each including: from among the triangles formed from the three points, the virtual plane associated with the triangle is located lower than each lead from the triangle in which the center of gravity of the electronic component is located in the triangle Means for selecting such a virtual plane.
4. A lead lift detection device for an electronic component according to claim 1. 8. An approximate straight line relating to a lead height is calculated for each lead row, and two leads having the lowest Z-axis (height direction) intercept of a straight line passing through each lead height with an inclination of the approximate straight line are determined. 7. The lead lift detecting device for an electronic component according to claim 6, wherein the electronic component is extracted one by one. 9. In order to determine whether the center of gravity of the electronic component is a triangle located in the extracted triangle, one side of the triangle closest to the center of gravity is extracted and passes through the center of gravity in parallel with the one side. 8. The method according to claim 7, further comprising determining whether a virtual plane associated with the triangle is positioned lower than each of the leads only when the straight line intersects the other two sides of the triangle within a predetermined range of XY coordinates. 4. A lead lift detection device for an electronic component according to claim 1. 10. A lead float detection device for an electronic component having a plurality of leads extending outwardly from a main body part arranged in a row on four sides of an electronic component. A laser device disposed below the component, means for irradiating a laser beam from below toward the lead of the electronic component from the laser device to detect the height of the lead, and the lowest lead in each lead row. Means for extracting four lead rows for each one point; means for calculating virtual planes formed by selecting three points from the extracted four points; calculating lead floating amount for each calculated virtual plane Means for detecting the floating of a lead of an electronic component, comprising: