JPH0726834B2 - Optical device for lead shape inspection of electronic parts and lead shape inspection device for electronic parts using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the shape of lead bends and flatness of electronic parts.
In particular, it relates to an optical device for inspecting the flatness of leads.

[0002]

2. Description of the Related Art When a flat package type IC or the like is mounted on a printed circuit board, the connection with the terminal portion formed on the printed circuit board is made to be good, so that the shape of the IC lead has the following disadvantages. Inspect for points. (1) The local or total bending of the IC lead 31 as shown in FIG. 8 and the pitch P, and (2) the floating of the flat portion of the IC lead 31 from the reference plane O as shown in FIG. is there.
Various devices have been proposed for inspecting the shape of the IC lead. A description will be given below with reference to the drawings.

<First Conventional Example> FIG. 10 shows a schematic configuration of an apparatus according to the first conventional example. The IC is placed on the glass stage 31 (the back side is a screen) that transmits light, and the IC is illuminated from the 90 ° and 45 ° directions with respect to the stage surface. And I projected on the back screen
The projected image of the C lead 31 is picked up by a plurality of CCD cameras 32 below the glass stage 30. The image data of the obtained 90 ° illumination image is analyzed by the image processing unit 33 to inspect its bending, and the floating of the IC lead is inspected from the image data of the 45 ° illumination image.

However, with the recent high-density mounting of ICs, the IC size has been reduced, and the lead spacing has been reduced accordingly, and the smallest IC with a lead spacing of 0.3 mm pitch has been developed. Being developed. When the above-mentioned device is used for measuring the shape of such a fine pitch IC lead, the projected images of the leads overlap at the time of 45 ° illumination, and it becomes impossible to measure the floating amount of the leads. Therefore, the following device has been proposed.

<Second Conventional Example> FIG. 11 shows a schematic configuration of an apparatus according to the second conventional example. The characteristic part of this device is that, in addition to the bending illumination lamp 34 arranged in a 90 ° direction with respect to the stage surface for measuring the bending of the lead, the floating illumination lamp 35 for measuring the floating amount of the lead is installed in the stage. It is arranged on the extension surface of the surface. According to this, the floating lighting
The light 35 passes through between the surface of the glass stage 30 and the bottom surface of the IC (this distance is called a standoff) and illuminates the IC lead 31 from the horizontal direction. Then, the projected image of the IC lead 31 is guided to the CCD camera 32 by the mirror m and picked up. Since the IC leads 31 are illuminated from the horizontal direction, even if the ICs have a fine pitch, the projected images of the leads do not overlap with each other and a subtle floating amount can be measured.

However, the standoff is about 0.1 m.
With a thin IC having a size of about m 2, light does not sufficiently pass between them, and a clear horizontal projection image of the lead cannot be obtained, and measurement is difficult. Further, since it is possible to measure the IC lead in only one direction with one measurement, it takes time and effort to invert the IC direction by 180 °.

In order to solve this, a method of installing an illuminating lamp just below the IC and illuminating each IC lead row simultaneously from the horizontal direction can be considered. However, with a standoff length of 0.1 mm, it is not possible to install lighting between them. Therefore, an apparatus using the following jig has been proposed.

<Third Conventional Example> FIG. 12 shows a schematic structure of a main part according to the third conventional example. An illuminating lamp 37 is installed in a jig 36 having rising portions formed at the left and right ends so that the base of the IC lead 31 is supported. The light from the illuminating lamp 37 is guided to the top of the rising portion by the mirror 38, and the light is emitted in the direction perpendicular to the IC lead 31 from there.
By using this jig 36, it is possible to illuminate each IC lead row at the same time from the right angle direction, and the problems of the first and second conventional examples are eliminated.

[0009]

However, when using the jig 36 as in the third conventional example, it is necessary to prepare the jig 36 according to various sizes of the IC. That is, the bases of the IC leads 31 must be accurately supported by the rising portions at the left and right ends, and for this purpose, the size of the IC body (the distance between the lead rows) and the distance between the rising portions must match. Need to be Since the interval between the rising portions is peculiar to the jig, it is not possible to support the IC corresponding to various sizes of the IC, and the versatility of measurement is lacking.

The present invention has been made in view of the above circumstances, and it is possible to simultaneously inspect each lead row of an electronic component having a relatively short lead pitch and standoff, and at the same time, to test electronic components of various sizes. It is an object of the present invention to provide an optical device for inspecting a lead shape of an electronic component that can deal with the lead shape inspection and a lead shape inspecting apparatus for an electronic component using the same.

[0011]

The present invention has the following constitution in order to achieve the above object. That is, an optical device for inspecting a lead shape of an electronic component of the present invention includes (1) a partially or entirely translucent stage on which the electronic component is mounted, and (2) a lead row facing the electronic component. (3) A diffraction grating which is attached to the stage in the gap and has light-transmitting portions and light-shielding portions along the lead rows arranged in one row or alternately.
And a light source for illuminating the diffraction grating from below. Further, in addition to the above configuration, the lead shape inspection apparatus for an electronic component of the present invention is (4) an image pickup device that captures a projected image of each lead row of the electronic component illuminated by the diffracted light from the diffraction grating. It is characterized by having means.

[0012]

According to the optical device for inspecting the lead shape of the electronic component of the present invention, the diffracted light determined by the wavelength of the light incident on the diffraction grating from the light source and the incident angle thereof and the pitch of the light transmitting portion of the diffraction grating. The angle of is set so as to be directed horizontally from the inside to the outside of the lead row of the electronic component on the stage, whereby each lead row can be sharply illuminated with the diffracted light at once. In this case, the size of the electronic component may be at least large enough to straddle the diffraction grating, and is not limited to one type. Further, according to the lead shape inspection apparatus for an electronic component of the present invention, since the projection image of each lead row illuminated by the diffracted light is captured by the image pickup means, the image data of each lead row required for inspection is once obtained. Can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a lead shape inspection device using the lead shape inspection optical device of the present invention. The optical device converts the output light of an illuminating lamp 2 arranged as a light source for illuminating the IC lead 1 into a bundle of parallel rays by a lens 3 and guides it to a diffraction grating 5 via a glass plate 4. Then, the light is diffracted at about 90 ° here, and the light is illuminated from the inside to the outside of the IC lead 1 through the glass stage 6 on which the IC is mounted.

As shown in the plan view of FIG. 2, the diffraction grating 5 has a large number of light-shielding filaments 8 formed on a transparent plate 7 made of glass or the like at a required pitch so that the light-shielding portion and the light-transmitting portion are arranged in a line or. It is configured to be arranged alternately. And the filament 8 of the diffraction grating 5
The IC is placed on the glass stage 6 so that the column direction (X direction) of the IC leads 1 is aligned with and the IC leads 1 on both sides straddle the diffraction grating 5.

As is well known, the position where the maximum value of the brightness of the diffracted light by the diffraction grating 5 appears is in the direction of θ (referred to as a diffraction angle) that satisfies the following expression (a). d (sinθo + sinθ) = mλ (a) In the above equation, the symbol d is the pitch between the light transmitting portions (slits) of the diffraction grating 5, and θo is the diffraction grating. Incident light angle to 5, m
Is an integer and λ is the wavelength of the incident light. Now, as shown in FIG. 3, when the incident light B1 converted into a parallel light flux is incident on the diffraction grating 5 at the same angle as the normal line n perpendicular to the surface of the glass stage 6, θo is “0 °” because it is expressed as a deviation angle from the normal line n. Substituting this into equation (a) and rewriting it yields sin θ = mλ / d ... (b).

That is, when the illuminating lamp 2 is installed just below the glass plate 4 as in this example, the diffraction angle is determined by the wavelength of the incident light and the pitch of the light transmitting portions of the diffraction grating 5. Therefore, these values may be set so that the maximum value of the brightness of the diffracted light appears from the inside to the outside of the IC lead 1. Then, the IC lead 1 can be illuminated sharply, and a sharp projection image used for inspecting the lead shape can be obtained.

In the above structure, the glass stage 6 is installed on the diffraction grating 5, but the glass stage 6 is provided for the purpose of protecting the diffraction grating 5.
Therefore, it is not particularly necessary, and the glass plate 4 may be eliminated and used as an IC inspection stage. in this case,
Since the diffraction grating 5 is located directly below the IC, the wavelength of the incident light and the pitch value of the light transmitting portions of the diffraction grating 5 are determined so that the diffraction angle is just 90 °. Further, in this case, a vertically long groove into which the diffraction grating 5 is inserted may be formed in the glass plate 4, and the diffraction grating 5 may be embedded in the groove.

Next, an inspection apparatus for inspecting the lead shape using the above-mentioned optical device will be described. As shown in FIG. 1, this inspection device divides the optical path of the diffracted light (projected image of the IC lead 1) obtained by the above optical device with a half mirror 10, and one of them is used as a lens system 11 for measuring the amount of floating. The other side is led to the lens system 12 for pitch measurement through the reflection mirror 20. Then, the area-type CCD sensor 13 (CCD camera) captures the output light image from the lens system 11 for measuring the floating amount, and the linear CCD sensor 14 captures the output light image from the lens system 12 for pitch measurement. The image data is sent to an image processing unit (not shown) for inspection.

This inspection device is installed corresponding to each IC lead 1 arranged in a row, and in the case where a row of leads 1 is provided on both sides of the IC body as shown in the figure, The above-mentioned components are arranged on the left and right sides thereof.

The lens system 11 for measuring the floating amount is shown in FIG.
, A plurality of cylindrical lenses are arranged on the front stage side and the rear stage side with the diaphragm 15 interposed therebetween. The cylindrical lens group 16 on the front side is arranged so that its axis is in the X direction, and magnifies the projected image of the IC lead 1 in the Y direction in the drawing.
On the other hand, the cylindrical lens group 17 on the rear side is arranged such that its axis is in the Y direction, and the image magnified in the Y direction by the cylindrical lens group 16 on the front side is contracted in the X direction.

Here, it is assumed that the projected image of the IC lead 1 is as shown in FIG. The shaded area is the shadow area. This projected image is first magnified in the Y direction by the cylindrical lens 16 on the front side and converted into an image as shown in FIG. The Y direction is the direction from the reference line O (corresponding to the reference surface of the glass stage 6) in FIG. 5 to the bottom surface of the lead 1, that is, the floating direction of the lead 1. The projected image with the floating direction enlarged is
The diaphragm 15 narrows the range to D in FIG. This range D
Is preferably set to a minimum range including just the floating portion of the lead 1.

The focused image is a cylindrical lens 17 on the rear side.
In the X direction, and as a result, the projected image S as shown in FIG.
Is obtained. As described above, the size of the projected image is reduced by the diaphragm 15 and the cylindrical lens 17 on the rear side, but the image in the Y direction (floating direction) remains enlarged by the cylindrical lens 16 on the front side. Therefore, it is possible to measure the floating amount that requires higher accuracy based on the image magnified in that direction, and since the size of the projected image itself is reduced, a CCD that captures this image is used. camera
The number of installations of 13 is reduced.

For example, the projected image of the IC is magnified 2.75 times in the Y direction, and the aperture range D is set to about 6.6 mm, which is the length of one side of the effective field of view of the ordinary CCD camera 13. Since the number of pixels in the Y direction by the CCD camera 13 is usually about 480,
One pixel corresponds to about 13.75 μm. On the other hand, when measuring the floating amount, a resolution of 5 μm is required. That is, when capturing a 1 × image, the length of one side of the effective field of view is
It is necessary to use a 2.4 mm CCD camera 13 (2.4 mm ÷ 4
80 = 5 μm), the number of CCD cameras 13 installed increased as the length decreased. However, if the projected image is magnified 2.75 times in the Y direction as in this example, the length of the projected image per pixel is 1 / 2.75 times that of the normal-sized image, that is, 13.7 times.
It becomes 5 μm / 2.75 = 5 μm.

That is, using the ordinary CCD camera 13,
The resolution of μm can be realized, and the number of CCD cameras 13 to be installed can be greatly reduced by adding the reduction in the X direction.

One of the pitch measuring lens systems 12 is, for example, the cylindrical lens 17 on the rear stage side whose axis is in the X direction and Y direction.
The size of the projected image is reduced in the X and Y directions by arranging it in two stages so as to follow each of the directions. The pitch measurement is to measure the pitch between the IC leads 1.

In the above-mentioned embodiment, the IC having the leads 1 on both sides of the IC is exemplified, but this type of I
The IC is not limited to C, and an IC of a type in which the lead 1 extends from all side surfaces (4 directions) of the IC can be inspected by the same principle. That is, the same diffraction grating 5 is installed above the diffraction grating 5 shown in FIG. 2 in an orthogonal posture, and is placed on the glass stage 6 so that the center position of the IC is located at the orthogonal position. To do. The inspection mechanism including the lens system and the CCD camera is arranged in four directions.

[0027]

As is apparent from the above description, the optical device for inspecting the lead shape of an electronic component according to the present invention is provided with a diffraction grating on a translucent stage on which the electronic component is mounted, and the diffracted light Since the leads of the electronic component are illuminated by using, the angle of the diffracted light is set so as to go from the inside of the lead row of the electronic component to both outsides, and each lead row of the electronic component is Can be sharply illuminated with. Further, the size of the electronic component has only to be at least large enough to straddle the diffraction grating, and is not limited to one product type, and various sizes of electronic components can be supported.
Further, since the lead shape inspection apparatus for electronic parts of the present invention captures the projected image of each lead row illuminated by the diffracted light by the image pickup means, the image data of each lead row required for the inspection can be obtained at once. Therefore, the inspection time can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical device for inspecting a lead shape of an electronic component and an apparatus for inspecting a lead shape of an electronic component using the same according to an embodiment of the present invention.

FIG. 2 is a plan view of an IC in an optical device for inspecting a lead shape of an electronic component.

FIG. 3 is a partial front view illustrating the operation of the optical device for inspecting a lead shape of an electronic component.

FIG. 4 is a perspective view showing a configuration example of a lens system in a lead shape inspection device for an electronic component.

FIG. 5: I by an optical device for lead shape inspection of electronic parts
It is the figure which showed the projection image of C lead.

FIG. 6 is a diagram of a projected image magnified by the lens system.

FIG. 7 is a diagram of a projected image finally obtained through the lens system.

FIG. 8 is a view showing how IC leads are bent in a conventional example.

FIG. 9 is a diagram showing how the IC leads float in a conventional example.

FIG. 10 is a diagram showing a schematic configuration of an apparatus according to a first conventional example.

FIG. 11 is a diagram showing a schematic configuration of an apparatus according to a second conventional example.

FIG. 12 is a diagram showing a schematic configuration of an apparatus according to a third conventional example.

[Explanation of symbols]

 1 ... IC lead 2 ... Illumination lamp (light source) 5 ... Diffraction grating 13 ... CCD camera 14 ... Linear CCD sensor

Claims (2)

[Claims] 1. A light-transmissive portion which is attached to the stage in a gap between a partially or entirely translucent stage on which an electronic component is mounted and a lead row facing the electronic component, and which extends along the lead column. An optical device for inspecting a lead shape of an electronic component, comprising: a diffraction grating in which a plurality of lines and light-shielding sections are arranged in a row or alternately and a light source that illuminates the diffraction grating from below. 2. A lead shape inspection device for an electronic component, wherein a projection image obtained by illuminating a lead row of an electronic component is analyzed by an image processing device to inspect the bending and flatness of each lead. A partially or wholly transmissive stage to be placed, and a row of a light-transmitting portion and a light-shielding portion attached to the stage in the gap between the lead rows facing each other of the electronic component, or one row or A diffraction grating arranged alternately, a light source for illuminating the diffraction grating from below, and an imaging means for respectively capturing a projected image of each lead row of the electronic component illuminated by the diffracted light from the diffraction grating. A lead shape inspection device for electronic parts, characterized by being provided.