JPH03141658A - Detection of floating of lead of surface-mounting type ic element - Google Patents

Abstract

PURPOSE:To facilitate the discrimination of the floating of a lead on the surface of a liquid or solidlike material whose contact surface is selectively deformed due to the contact of the lead, by optically detecting the deformation of a contact surface due to the contact of the lead. CONSTITUTION:A required surface-mounting type IC element 4 is supported approximately horizontally. A lead 5 is made to face or brought into contact with the surface of a liquid 14 which is contained in a cell 10a of a transparent container 10. When the lead 5 is floated by the contact, the surface tension is not applied on this part since the tip side of the lead 5 is separated from the liquid 14. Therefore, a lower sloped part 14a is not formed at a corresponding boundary surface. Therefore, this state is picked up with a TV camera 11, and the image is processed in an image processing device 12. Thus it can be decided that the lead is not normal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for detecting floating leads of a surface-mounted IC element.

(Prior art) Surface-mounted ICs such as QFP package IC elements
BACKGROUND ART Elements are mounted and mounted on wiring boards to reduce the size of circuit configurations or circuit components. By the way, mounting/mounting (mounting) of the QFP package IC element etc. on the wiring board surface is generally performed as shown in FIG. 6(a).
The embodiment is schematically shown in (b). That is, for example, solder paste 3 is applied by printing on the surface of 2 required pads provided on a predetermined region of the wiring board 1, and the QFP package IC element 4 is positioned (also the position of the leads 5 is determined). After the lead 5 is placed on the surface of the predetermined pad 2 by reflowing the solder paste 3, the lead 5 is mounted on the predetermined pad 2 surface. Above: When mounting the own QFP package IC element 4, if the leads 5 of the QFP package IC element 4 to be mounted are floating, as shown in FIG. However, there are cases where it is not possible to reliably solder onto two predetermined pads.

Therefore, when mounting the QFP package IC device, etc., the QFP package I
The presence or absence of floating leads of the C element is detected and selected in advance by the following method.

The first method, as schematically shown in FIG. The lead 5 is irradiated with light, and lifting of the lead 5 is detected from the shadow formed.

That is, when the lead 5 is irradiated with light from diagonally above, floating of the lead 5 is detected by utilizing the fact that the shadow of the floating lead 5a is shorter than the shadow of the normal lead 5b.

The second method, as schematically shown in FIG. 9, is to detect floating of the lead 5 by reflection of laser light. That is, the surface-mounted IC element 4 is supported almost horizontally, a laser beam is irradiated from one end to the other end of each lead 5, and the device is made to float by the reflected light (area or length from which the reflected light can be obtained). Detects and determines the presence or absence of a lead. In addition, in FIG. 9, 8 is a laser beam emitting part, and 9 is a laser beam (reflected light) input part.

(Problems to be Solved by the Invention) However, the above lead floating detection method has the following disadvantages.

First, in the case of the first method, if the lead 5 is slightly lifted, it is difficult to detect the difference in the length of the shadow, making it difficult to distinguish. Moreover, since the lengths of the leads 5 of the surface-mounted IC element 4 vary, there is a problem that it is impossible to distinguish between variations in the length of the leads 5 and floating leads 5.

On the other hand, in the case of the second method, a mechanism for horizontally supporting the laser oscillator 8, laser detector 9, and surface-mounted IC element 4 and moving them in the X-Y directions is required, making the device complicated or expensive. There is a problem of becoming Furthermore, in the packaged IC element 4, the package surface and the extended leads 5 do not always have a certain level of parallelism, so the detection accuracy cannot be said to be sufficient.

The present invention has been made in response to the above-mentioned circumstances, and it is an object of the present invention to provide a method for easily detecting and determining floating leads of surface-mounted IC elements without using complicated or expensive equipment.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a surface-mounted IC device on a liquid or semi-solid object surface whose contact portion surface selectively deforms upon contact with a lead of a surface-mounted IC device. Surface mount type I so that the leads of the type IC element are in contact with each other.
The present invention is characterized in that the C element is supported substantially horizontally, and the deformation of the contact surface caused by the contact of the leads is optically detected to determine whether or not the leads are floating.

(Function) In the present invention, the surface-mounted IC element is supported substantially horizontally, and the lead portion is brought into contact with the surface of a liquid or semi-solid object. In the case of liquid, due to the contact of the lead part, a skirt is created between the liquid surface and the lead due to the surface tension of the liquid, which corresponds to the contact state. In addition, in the case of a semi-solid object, unevenness occurs on the surface of the semi-solid object depending on the contact state of the lead part, so the degree of floating of the lead can be determined by optically detecting the state of the unevenness. Detected.

(Example) The present invention will be described in detail below with reference to FIGS. 1 to 4. FIG. 1 is a partial cross-sectional view showing a schematic configuration of an apparatus used to carry out the method of the present invention, in which 10 is a transparent container, and 11 is a transparent container disposed so as to be movable in a substantially horizontal direction on the transparent container. A television camera, 12 is a device for image processing the image taken by the television camera 11, and 13 is a light source that illuminates the transparent container. Therefore, the transparent container 10 can contain the liquid 14 to a required depth in the region corresponding to the lead 5 portion of the surface-mounted IC device 4 which is the object to be inspected.
a, and there is also a lead 5 inside this [10a].
It is configured so that it can be placed and obtained.

Next, a means for detecting lead floating using the apparatus having the above configuration will be explained. Required surface mount IC element 4, for example QF
The P package IC element is supported almost horizontally, and its QF
The lead 5 portion of the P package IC element 4 is brought into contact with the surface of the liquid 14 contained in the TFL 10 a of the transparent container 10 . Due to the contact between the lead 5 and the liquid 14, when the lead 5 is normal, as shown in FIG. 2(a).
The state shown in FIG. 2(b) is shown in cross section and in plan view in FIG. 2(b). In other words, when the lead 5 is in a normal state, the surface tension of the liquid 14 (
Wi14a entirely on their interfaces (adhesive force)
is formed. However, in this state, the TV camera 11
The image is captured by the image processor 12, and through image processing, it can be accurately determined that the lead and the like are normal.

On the other hand, if the lead 5 is floating, it will exhibit a state as shown in cross section in FIG. 3(a) and in plan view in FIG. 3(b). In other words, when the lead 5 is in an abnormal state (floating), the tip side of the lead 5 is exposed to the liquid 14.
Since the surface tension (adhesive force) does not reach that portion (region) because it is separated from the surface, the hem 14a is not formed on the corresponding boundary surface. Therefore, this state is imaged by the television camera 11, and through image processing by the image processing device 12, it can be accurately determined that the lead 5 is not normal.

Incidentally, FIG. 4 is a plan view showing an example of the detected lead row extending on one side of the QFP package IC element 4 as described above.

In the above example, a liquid is used and the lead 5 is
However, even if a semi-solid substance such as silicone rubber gel is used instead of the liquid, it is possible to detect and determine whether the lead 5 is normal or floating in the same way as described above. obtain. That is, as shown in cross section in FIG. 5, while supporting the QFP package IC element 4 almost horizontally on the surface of the silicone rubber gel 15 whose surface is smoothed, the lead 5 portion of the QFP package IC element 4 is placed. Press with constant pressure. If the lead 5 is normal due to this suppression of the lead 5 portion, a depression (deformation) 15a corresponding to the silicone rubber gel is formed, including the tip end side of the lead 5, as shown in cross section in FIG. 5(a). arise. Furthermore, if the lead 5 is not normal (there is some floating), no corresponding depression (deformation) is produced on the surface of the silicone rubber gel 15, as shown in cross section in FIG. 5(b). It is possible to accurately determine whether or not the lead 5 is normal by capturing an image of the presence or absence of such deformation, the degree of deformation, and the state thereof using, for example, a television camera and processing the image using an image processing device.

[Effects of the Invention] As explained above, according to the method of the present invention, surface-mounted IC
Each lead extending in the lateral direction of the element uses the surface tension or adhesive force of a liquid or the elastic deformation of a semi-solid material to detect the floating state of the lead by a method that expresses these effects in an amplified form. Ru. Since the above-mentioned deformation and action can be amplified and expressed, even minute lead floating can be detected sufficiently and with high precision. Furthermore, expression in the amplified form can not only be easily achieved using ordinary image processing techniques, but also does not require a complicated processing mechanism, so it can be said to bring about many practical advantages.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the configuration of an apparatus used to carry out the method of the present invention, and FIGS. 2 to 5 schematically show the state in which floating leads of a surface-mounted IC element are detected in the method according to the present invention. Figure 2 (a) is a cross-sectional view when the lead is normal, Figure 2 (b) is a plan view when the lead is normal, and Figure 3 (a) is a cross-sectional view when the lead is not normal. 3(b) is a plan view when the leads are not normal. FIG. 4 is a plan view of the lead row. FIG. 5(a) is a sectional view when the leads are normal. b) is a plan view when the leads are not normal, Figures 6(a) and (b) are cross-sectional views showing the state in which a surface-mounted IC element is mounted on a wiring board, and Figure 7 is a surface with floating leads. Mounting type IC element on wiring board.
A cross-sectional view showing a soldered state, and FIGS. 8 and 9 are schematic diagrams showing aspects of a conventional method for detecting floating leads of a surface-mounted IC element, respectively. 1...Wiring board 2...Printed conductor land 3...Solder paste 4...Surface mount type IC element 5...Surface mount type IC element lead 5a...
・・Unnormal lead (IV! Listening) 5b・・・・
... Normal lead (no floating) 10 ... Transparent container 11 ... Television camera 12 ... Image processing device 13 ... Light source 14 ... ...Liquid 14a...Deformation of the semi-solid object 15a...Semi-solid object formed by the liquid

Claims (1)

[Claims] The surface mount type IC element is placed almost horizontally on a surface of a liquid or semi-solid object whose contact surface is selectively deformed when the lead of the surface mount type IC element contacts. 1. A method for detecting floating leads of a surface-mounted IC element, characterized in that the presence or absence of floating of the leads is determined by optically detecting deformation of a surface of a contact portion caused by the contact of the leads.