JPH0555334A - Defect detection method for lead terminals of surface mount components - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for detecting a defective portion of a lead terminal of a surface mount component capable of determining the floating of the lead terminal by a simple method. A reader obtained by irradiating a lead terminal of an electronic component with light rays from at least two or more different angles.
In the method of detecting the floating of the lead member from the variation amount of the projected image of the lead terminal, the light ray group is irradiated from above while the electronic component is placed on the light transmitting base, and the light transmitting base is irradiated. A projection image formed on the translucent base is picked up by an image pickup means arranged below the table, and the variation amount of the projected image is S1, and the tip portion of the lead terminal is irradiated and projected onto the translucent base. When the angle formed between one light beam and the transparent base surface is θ, the floating amount h of the tip portion of the lead terminal is detected by h = S1 tan θ.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead terminal of a mounting component soldered on a surface mounting printed wiring pattern, and particularly to a lead terminal of a surface mounting component capable of accurately detecting a defect such as floating. The present invention relates to a defect detection method.

[0002]

2. Description of the Related Art When an electronic component such as a flat package IC is mounted on a printed pattern on a board, a rectangular shape is formed so as to correspond to a large number of lead terminals led out from the peripheral portion of the IC or the like. A method in which a wiring pattern is formed in advance on a printed circuit board and the tip of each lead terminal and each pattern are connected by soldering is generally adopted.

As a soldering method, a predetermined amount of cream solder is printed and formed on each pattern, and a lead terminal is placed on the cream solder to heat and melt it.
A reflow method of cooling and solidifying after that is often used.

By the way, there is a variation in the shape of the lead terminal of the mounted component before the mounting, and this variation causes the solder connection failure. That is, the lead terminal may float from the pattern part or the solder due to the variation in the downward protrusion length of the lead terminal, the floating due to the bending in the vertical direction, and the lateral bending of the tip of the lead terminal. A poor connection state that solidifies may occur.

For this reason, it is necessary to check the state of the lead terminals before mounting, but it is difficult and inefficient to visually judge the quality of the lead terminals of the miniaturized electronic component, and In order not to reduce the work efficiency in the automatic mounting process, it is necessary to detect defective leads by the recognition machine.

FIG. 3 is an explanatory view of a conventional method for judging the quality of a lead terminal of an electronic component before mounting, which is an IC.
Before the component 1 is sucked and held by the suction tool 3 and conveyed onto the printed circuit board, the camera 5 checks whether the shape of the lead terminal 2 is good or bad. That is, in this conventional method, the screen 7 is arranged above the IC component 1, and the irradiation light from the illumination means 9 arranged on both the left and right sides of the IC component 1 is reflected by the screen 7, and the reflected light is guided to the camera 5. The quality is determined based on the image information thus obtained based on predetermined image processing.

FIGS. 4 (a) and 4 (b) are explanatory views of an image obtained by a conventional image processing method. FIG. 4 (a) is a binary image obtained by binary processing, and FIG. The multi-valued image obtained by is shown.

Here, the floating state of the lead terminals means a state in which the lead terminals are bent in a vertical direction with respect to the mounting surface, and the bending state of the lead terminals is in a horizontal direction with respect to the mounting surface. It is a bent state.

In the binary processing when the lead terminal 2 is floating, the length of the floating lead terminal 2a is shorter than that of a normal lead terminal as shown in FIG. 4 (a). Be seen.

On the other hand, in the multi-value processing, as shown in FIG. 4B, the depth of focus of the lens is deviated to cause blurring, and an abnormal lead terminal image appears as a density difference with respect to a normal lead terminal.

Therefore, by detecting these outputs, a normal electronic component is mounted at a predetermined position on the printed circuit board, and if the lead bending is more than the allowable value, the electronic component is discarded and the next electronic component is discarded. Is sucked by the suction tool and the lead bend is detected.

However, since the above-mentioned conventional method uses planar image processing, the recognition processing in the depth direction such as the lead floating is naturally limited due to the accuracy problem in the detector such as a camera. There was a point.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems in the conventional lead bend detecting device for electronic parts as described above, and determines whether the lead terminals are floating or not by a simple method. It is an object of the present invention to provide a method for detecting a defective portion of a lead terminal of a surface mount component that can be used.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, a method for detecting a lead state according to the present invention irradiates a lead member with light rays from at least two light sources at different angles and obtains the light obtained by the irradiation. -The floating of the lead member is detected from the variation of the projected image of the lead, and the light ray group is irradiated from above while the electronic component is placed on the transparent base, and the transparent base is also irradiated. The projection image formed on the translucent base is picked up by the image pickup means arranged below, and the variation amount of the projected image is S1, and the tip of the lead terminal is irradiated and projected onto the translucent base. When the angle formed between one light beam and the light-transmitting base surface is θ, the floating amount h of the tip portion of the lead terminal is detected by the formula h = S1 tan θ.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an electronic component shape inspection apparatus according to the present invention, in which an IC component 11 is mounted on an optic fiber plate (translucent base) 12 and a lead terminal 13 is provided. The shape is checked.

That is, the first light source 15 is arranged above the lead terminal 13 extending from the IC component 11 so as to have a predetermined angle .theta.1, and has a predetermined angle .theta.2 with respect to the lead-out direction of the lead terminal 13. The second light sources 17 arranged in this way respectively irradiate light toward the tip of the lead terminal, and the projected image transmitted through the optic fiber plate 12 is provided in a camera 19 (imaging means) provided vertically below the lead terminal. ). In this embodiment, the angle θ1 is 90 degrees and the angle θ2 is 60 degrees. The camera 19 is a CCD camera and is installed at a position where an image of the tip of the lead terminal projected onto the optic fiber plate 12 by the light from the light sources 1 and 2 can be captured from below. When the projection image obtained by irradiating light from the light source 15 in the apparatus configured as described above is a shadow image A and the projection image obtained by irradiating light from the light source 17 is a shadow image B, the two shadow images A and B are obtained. Thus, it is possible to determine whether or not the lead is floating and the amount of floating.

The determination method will be described in detail below.

First, as shown in FIG. 3A, the center portion of the tip of each lead terminal is detected from the image A, and the center portion of each terminal is detected by C.
1, C2, C3 ... And each central portion C1, C2, C3
By measuring the intervals P1 and P2 of ..., it is detected whether or not the lead pitch is as specified. Then, for example, when there is no floating in any of the lead terminals as shown in FIG. 2, the lead terminals appearing in the images A and B have equal lengths as shown in FIGS. 3 (a) and 3 (b). Have However, as shown in FIG. 4, when the lead terminal 12 is floating, the projected image B (FIG. 5) obtained by irradiating the light from the light source 17 is formed when the lead exists at the normal position. The image forming position moves by S1 with respect to the projected image. Therefore, for example, when only the lead terminal at the center has a float, the lead terminal is shortened by S1 as shown in FIG.

The fluctuation of the image forming position at the tip of the lead terminal is relieved.
This is caused by the floating of the lead terminal, and the floating amount h of the tip of the lead is determined by the fluctuation amount of the image forming position S1 and the second light source 1
And the fiber plate 12 which is emitted from 7 and is projected onto the fiber plate 12 by irradiating the tip of the lead terminal.
When the angle formed between and is θ, it is expressed by the following equation.

H = S1 tan θ That is, the amount of change in the image forming position due to floating can be easily obtained by measuring the amount of movement S1 of the projected images A and B and the angle θ.

When the lead terminal is merely bent, one light source is enough to detect the amount of bending. Of course, when the bend is accompanied by floating, the floating amount can be detected by the above formula.

As described above, by irradiating light from two directions and processing the projected images formed at that time by using one camera, it is possible to detect the presence or absence and the amount of floating of the lead. it can.

[0023]

As described above, according to the present invention, light is emitted from two directions at a predetermined angle with respect to the lead-out direction of the lead terminal of the electronic component, and as a result, a projection image is formed on the optic fiber. Whether or not the lead terminal is floating and the amount of floating can be detected from the image, which is extremely effective in grasping the reliable lead state.

[Brief description of drawings]

FIG. 1 is a diagram showing an external configuration of an electronic component shape inspection apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a case where a lead terminal is normal.

3A and 3B are views showing images A and B of a normal lead terminal.

FIG. 4 is a view showing a state in which the lead terminal has a float.

FIG. 5 is a diagram showing a shadow image B in the case where the lead terminal is floating.

FIG. 6 is an explanatory diagram showing a conventional detection method.

7A and 7B are explanatory diagrams of an image obtained by a conventional image processing method.

[Explanation of symbols]

11 ... IC parts, 12 ... Optic fiber plate (translucent base) 13 ... Lead terminals, 15 ... First light source, 17 ...
..Second light source, 19 ... Camera (imaging means), A,
B ... image,

Claims (1)

[Claims] 1. A method for detecting a failure of a lead terminal for detecting a state of a lead terminal of an electronic component, which is obtained by irradiating a light beam to the lead terminal from at least two different angles. In a method of detecting the floating of a lead member from the variation amount of a projected image of a lead terminal, the electronic component is placed on a translucent base, and the light beam group is irradiated from above while the electronic component is radiated. A projection image formed on the translucent base is imaged by an image pickup means disposed below the translucent base, and the variation amount of the projected image is S1, and the tip of the lead terminal is irradiated to illuminate the translucent base. When the angle formed between one light ray projected on the upper surface and the transparent base surface is θ, the floating amount h of the lead terminal tip portion is detected by the following equation: h = S1 tan θ Detecting lead terminal defects of surface mount components.