JP2003130619A - Method and apparatus for detecting defective lead terminal of electronic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for detecting defective lead terminal of electronic parts, which can accurately detect the floating of a lead terminal for a short time. SOLUTION: Height data of each lead terminal of the electronic parts is acquired, and a test is carried out to decide whether the distance between each side and a hypothetical straight line of each lead terminal is within an allowable value, or whether the distance from a hypothetical plane of each lead terminal is within an allowable value. In the case such a decision is made that either the distance from the hypothetical straight line or the distance from the hypothetical plane is not within each allowable value, the least square plane is computed from the height data of each lead terminal, and the defective lead terminal is detected on the basis of the distance from the least square plane. In the above structure, the defective lead terminal such as the floating of lead can be rapidly and accurately detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting defective lead terminals of an electronic component, and more particularly, a lead floating of an electronic component mounted on a printed circuit board, a liquid crystal, a display panel substrate or the like by an electronic component mounting apparatus. And a method for detecting a defective lead terminal.

[0002]

2. Description of the Related Art In a conventional method for detecting a defective terminal such as a lead float, as shown in FIG. 6, an electronic component 2 is sucked by a suction nozzle 7a of a transfer head of a component mounting apparatus and transferred to a substrate. , The electronic component 2 is positioned above the laser device 40, laser light is emitted from the light projecting portion 41 of the laser device toward the lead terminal 2a of the electronic component, and the reflected light from the lead terminal is received by the light receiving portion 42. By doing so, the height Zi of each lead terminal 2a from the reference plane S is detected.

Then, as shown in FIG. 7, appropriate three lead terminals P1, P2, P3 are selected, and the height Z1 from the reference plane S of these lead terminals is determined by the method shown in FIG.
Z2 and Z3 are obtained, and the height Z0 of the virtual plane K including the three points P1, P2 and P3 is calculated by the plane equation aX + bY + cZ + 1 =
It is calculated by using 0.

Then, the height Zi of each lead terminal previously detected as described above and the height Z0 of the virtual plane K are obtained.
The float of each lead terminal is detected by obtaining the height difference ΔZ = Zi−Z0.

In this way, the three lead terminals P1,
The height Z0 of the virtual plane K including P2 and P3 is obtained, and the distance of each lead terminal with respect to this height Z0, that is, the height difference ΔZ is obtained. Since the electronic component 2 has a defective lead terminal, its mounting on the substrate is stopped.

[0006]

In such a conventional detection method, three arbitrary lead terminals are selected, and then a virtual plane including the three points of these lead terminals is calculated, and the virtual plane of each lead is calculated. The distance (height difference) is calculated. Therefore, for example, as shown in FIG. 4 (A), when the electronic component 2 having the lead terminal 2a which is largely curved downward is mounted on the substrate 9, the other lead terminal 2b is against the cream solder 9a on the substrate 9. If floating occurs, see Fig. 4.
As shown in (B), three lead terminals 2 with large curvature
When a is selected, when a virtual plane passing through the three points is obtained, the other lead terminals 2b with less bending are all located on the package side with respect to the virtual plane, so that the lead terminal 2a is within the allowable value K. However, there is a problem that it is difficult to identify the defective lead terminal because it is detected that the other normal lead terminal 2b is not within the allowable value K.

In addition, since the method of calculating the distance from the virtual plane including any three points cannot accurately find the abnormal lead terminal, it is useful for quality control based on the parts after inspection of lead floating. I couldn't do that either.

Further, the false recognition that a normal lead terminal is detected as abnormal due to a foreign substance such as dust adhering to the sensor window or the like appears at a relatively same place. However, the conventional detection method has a problem that the timing of cleaning the sensor window or the like cannot be notified to the operator or the cleaning device because the defective lead terminal cannot be identified.

Therefore, the present invention has been made in order to solve such a problem, and provides a method and apparatus for detecting defective lead terminals of an electronic component capable of detecting floating of lead terminals in a short time and with high accuracy. The task is to provide.

[0010]

The present invention provides a method and apparatus for detecting defective lead terminals of an electronic component mounted on a board by an electronic component mounting apparatus, wherein height data of each lead terminal of the electronic component is acquired, Inspecting whether the distance from the virtual straight line of each lead terminal on each side of the electronic component is within the tolerance, inspecting whether the distance from the virtual plane of each lead terminal is within the tolerance, When it is determined that the distance from the virtual straight line or the distance from the virtual plane is not within the allowable value, the least square plane is calculated from the height data of each lead terminal, and the defective lead is obtained based on the distance from the least square plane. It is characterized by detecting a terminal.

In such a configuration, the least square plane is calculated from the height data of each lead terminal, and the defective lead terminal is detected based on the distance from the least square plane. The terminal can be detected, and the defective lead terminal is detected based on the least-squares plane only when the virtual straight line of each lead terminal on each side or the distance from the virtual plane of each lead terminal is not within the allowable value. Therefore, high-speed inspection is possible.

In particular, if the virtual straight line is a least squares straight line obtained from the height data of the lead terminals on the relevant side, it is possible to accurately detect the defective lead terminal on each side.
If the virtual plane is determined from the three lead terminals, the calculation for obtaining the virtual plane is simplified and high-speed inspection is possible.

Further, if dust or dust adheres to the sensor window for measuring the height of the lead terminals, defective lead terminals are detected many times at the same location due to the dust. If not, try cleaning the sensor window. As a result, reliable inspection can be performed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the embodiments shown in the drawings.

FIG. 1 shows the appearance of an electronic component mounting apparatus for mounting electronic components on a board. In the figure, 1 is a main body of the electronic component mounting apparatus, 2 is an electronic component mounted by this apparatus, 3 is a tray on which the electronic component 2 is mounted, 4
Is a tray supply unit as a component supply unit for automatically supplying the electronic component 2 placed on the tray 3, 7 is a head unit having a suction nozzle 7a for sucking and mounting the electronic component 2 during mounting, and 5 is the x-axis of the head unit 7. X-axis robots that move in the direction, and 6a and 6b that form a part of an xy robot, and 6a and 6b that form a part of an xy robot that moves the head unit 7 in the y-axis direction together with the x-axis robot 5. Robot, 8 is 3
It is a dimension (hereinafter abbreviated as 3D) sensor, and captures a height image of the electronic component 2. Reference numeral 9 is a printed circuit board on which the electronic component 2 is mounted.

In such a component mounting apparatus, the component 2 mounted on the tray 3 is sucked by the suction nozzle 7a of the head portion 7 and moved onto the 3D sensor 8 by the x-axis robot 5 and the y-axis robots 6a and 6b. To be done. Then, the 2D image of the component 2 is captured by the 3D sensor 8, and the image is processed by software to perform positioning. Next, the 3D sensor 8 captures a 3D (height) image of the electronic component 2. The (height) image obtained by the 3D sensor 8 is processed by software to perform a 3D shape inspection such as lead floating of the component 2. If the inspection result is good, the electronic component 2 is placed on the printed circuit board 9 according to the positioning information. Is mounted at a predetermined position.

FIG. 2 shows the detailed structure of the 3D sensor 8. When acquiring the three-dimensional image data (height data) of the electronic component 2, the laser light source 8a is turned on and the laser light source 8a emits light. The light is converted into line light by a light projecting unit 8b that generates line light and can reciprocate in the left-right direction, and is applied to the lead terminal 2a of the electronic component 2 to scan the lead terminal. A CCD camera 8c is arranged below the electronic component 2, and the electronic component 2 is imaged. As will be described later, from this image, three-dimensional data for measuring the floating of the lead terminal 2a is acquired. Further, when the two-dimensional image data of the electronic component 2 is acquired and the positioning data is obtained, the illumination light source 8d is turned on, the electronic component is similarly imaged by the CCD camera 8c, and the deviation between the suction center and the component center is detected. Positioning data such as the deviation of the suction angle with respect to the reference angle is acquired.

In FIG. 2, 8e is a glass sensor window for protecting the sensor from dust, and 8f is a window.
Is an air blower for cleaning the sensor window.

In such a component mounting apparatus, as shown in FIG.
As shown in FIG.
Is picked up (sucked) by the suction nozzle 7a of the electronic component 2 and positioning data is acquired by the 3D sensor 8.
Is mounted on a predetermined portion of the printed circuit board 9 as shown in FIG. At this time, when the 3D sensor 8 detects a defect in the lead terminal such as floating of the lead, the mounting of the electronic component is stopped.

Next, a method of detecting a defective lead terminal from the height data of each lead terminal obtained by the 3D sensor 8 will be described with reference to the flowchart of FIG.

In the inspection of defective leads, whether the height difference (distance) of the lead terminals on each side from the least square line is within an allowable value, and the height difference from an imaginary plane passing through any three points. Since it is determined whether or not is within the allowable value, each allowable value is set. The allowable value of the height difference from the virtual plane is, for example, the same as the mask thickness of the solder paste.
Set to 00 μm. In addition, since the allowable value of the height difference from the least squares line is an inspection for each side, the inclination of the entire side is not considered, so a set value smaller than the allowable value of the distance from the virtual plane, here, 90 from the plane
%, Which is 180 μm.

First, the laser light source 8 is set by the 3D sensor 8.
A is turned on, and the lead terminals of the electronic component 2 are scanned with the line light to obtain height data (step S1). From the measured height data of each lead terminal for each side, multiple linear regression is performed. Linear approximation of terminal height on side aX + b =
Y is obtained, and as shown in FIG. 4C, a least squares straight line L is obtained for each side. Then, each lead terminal 2a,
The height difference of 2b from this least-squares straight line L is obtained (step S2), and it is determined whether or not this height difference is within the allowable value K (180 μm) (step S3). If a lead terminal that is not within the allowable value is detected, it is determined that the lead terminal is floating, and the process proceeds to step S6.

On the other hand, when it is determined in step S3 that the height difference of each lead terminal on each side is within the allowable value, a plane approximation formula a + bx + including three points of any three lead terminals is obtained.
A virtual plane K that can be expressed by cy = z is calculated (FIG. 7), and a height difference ΔZ with respect to this virtual plane is obtained (step S
4).

If it is determined that the height difference with respect to the virtual plane K is within the allowable value, the process proceeds to step S7 to mount the electronic component on the board, while it is determined that there is a lead terminal that does not fall within the allowable value. Is output, the determination “defective (NG)” is output, the process proceeds to step S6, and mounting of the component on the board is stopped.

When "defective (NG)" is determined in steps S3 and S5, it is detected in step S6 which lead terminal of the mounted component is bent and defective.
Therefore, the least squares plane is calculated based on the measured height data of each lead terminal. This is performed by obtaining the plane approximation formula a + bx + cy = z by multiple linear regression. That is, the plane equation can be obtained from the following equation.

[0026]

[Equation 1] The distance of each lead is calculated from the least squares plane obtained above. The distance from the least-squares plane gives a result of ±, so that a lead terminal having a distance larger than 100 μm, which is ½ of the set allowable value, is output to the operator as a defective terminal.

The height data of each lead terminal on the side with the defective terminal is stored in the memory. Then, at the time of inspecting the same component, similar height data is stored in the memory, and the standard deviation of each lead terminal on the side for 10 measurements is calculated. In this way, when the same component is repeatedly measured and the same terminal of the same component type repeatedly outputs "defective", an error occurs due to dust adhering to the sensor window 8e of the 3D sensor 8. Sensor window 8e
The dust adhering to the sensor window is blown off during the time when the measurement is not performed by the blowing device 8f attached in the vicinity, and cleaning is performed to prevent the deterioration of accuracy. This can improve the reliability of the inspection.

In the above embodiment, step S4
Although the defect of the lead terminal is determined by examining the height difference from the virtual plane with three points as the reference, the same effect can be obtained by using other determination methods.

The automatic cleaning of dust adhering to the sensor window 8e is not limited to this method using the air blower 8f, but the same effect can be obtained by cleaning the sensor window with cloth or paper. In addition, when the dirt on the sensor window is detected when the dirt on the sensor window is detected, a message indicating that cleaning is necessary may be output to the operator instead of automatically cleaning.

[0030]

As described above, in the present invention, the least squares plane is calculated from the height data of each lead terminal, and the defective lead terminal is detected based on the distance from the least squares plane. Detects defective terminals such as floating leads. In that case, check whether the virtual straight line of each lead terminal on each side or the distance from the virtual plane of each lead terminal is within the allowable value, and only when it is not within the allowable value.
Since defective lead terminals are detected based on the least-squares plane, high-speed inspection is possible.

Further, since the virtual straight line is the least squares straight line obtained from the height data of each lead terminal on the relevant side, it is possible to accurately detect the defective lead terminal on each side, and the virtual plane is defined. Since the determination is made from the three lead terminals, the calculation for obtaining the virtual plane is simplified and high-speed inspection is possible.

Further, when the defective lead terminal is detected many times at the same place, the sensor window is cleaned, so that it is possible to prevent the inspection when dust or the like is attached to the sensor window. A reliable inspection can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view showing the external appearance of a component mounting apparatus used in the present invention.

FIG. 2 is a configuration diagram showing a configuration of a height sensor.

FIG. 3 is an explanatory diagram showing a component mounting process.

FIG. 4 is an explanatory diagram illustrating height measurement when a lead terminal has a float.

FIG. 5 is a flowchart illustrating a flow of detecting a defective lead terminal.

FIG. 6 is an explanatory diagram showing a state of measuring height data of lead terminals.

FIG. 7 is an explanatory diagram illustrating calculation of a distance of a lead terminal from a virtual plane.

[Explanation of symbols]

2 electronic components 2a, 2b Lead terminal 7 head 7a Adsorption nozzle 8 3D sensor 9 substrates

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F065 AA51 AA61 CC27 DD03 DD06                       FF04 GG04 HH03 HH12 JJ03                       JJ26 MM03 QQ18 QQ24 QQ25                       RR05                 2G051 AA62 AB10 CA04 DA03 DA13                       DA17 EA12 EB01 ED23                 5F067 AA19 DB09

Claims (8)

[Claims] 1. A method of detecting a defective lead terminal of an electronic component mounted on a substrate by an electronic component mounting apparatus, the step of acquiring height data of each lead terminal of the electronic component, and each lead terminal on each side of the electronic component. The step of inspecting whether the distance from the virtual straight line is within the allowable value, the step of inspecting whether the distance from the virtual plane of each lead terminal is within the allowable value, or the distance from the virtual straight line or If it is determined that the distance from the virtual plane is not within the allowable value, a least square plane is calculated from the height data of each lead terminal, and a step of detecting a defective lead terminal based on the distance from the least square plane, A method for detecting a defective lead terminal of an electronic component, comprising: 2. The defective lead terminal detection method for an electronic component according to claim 1, wherein the virtual plane is a plane determined from three lead terminals. 3. The defective lead terminal detection method for an electronic component according to claim 1, wherein the virtual straight line is a least squares straight line obtained from height data of each lead terminal on the side. 4. The sensor window for measuring the height of the lead terminal is cleaned when the defective lead terminal is detected many times at the same location. A method for detecting a defective lead terminal of an electronic component according to. 5. A defective lead terminal detection device for an electronic component mounted on a substrate by an electronic component mounting device, a sensor for acquiring height data of each lead terminal of the electronic component, and each lead terminal on each side of the electronic component. Inspection means for inspecting whether the distance from the virtual straight line is within the allowable value and whether the distance from the virtual plane of each lead terminal is within the allowable value, and the distance from the virtual straight line is within the allowable value. If it is not, or if the distance from the virtual plane is not within the allowable value, the least square plane is calculated from the height data of each lead terminal, and the defective lead terminal is determined based on the distance from this least square plane. A device for detecting a defective lead terminal of an electronic component, comprising: 6. The defective lead terminal detecting device for an electronic component according to claim 5, wherein the virtual plane is a plane determined from three lead terminals. 7. The defective lead terminal detecting device for an electronic component according to claim 5, wherein the virtual straight line is a least squares straight line obtained from height data of each lead terminal on the side. 8. The electronic component according to claim 5, wherein the measurement window of the sensor is cleaned when the defective lead terminal is detected many times at the same place. Defective lead terminal detection device.