JPH08105722A - Illuminator for inspecting device external appearance and device external appearance automatic inspecting apparatus using the illuminator - Google Patents

Abstract

PURPOSE: To eliminate the illuminance unevenness, to carefully illuminate an object to be inspected and to precisely inspect the external appearance of a microminiaturized device by arranging many light emitting elements in which luminance is adjustable at a CCD camera as a center, and controlling the luminance of the elements based on an observation result. CONSTITUTION: A window frame for a camera 9 is provided at the center of a rectangular illumination frame 10, and light emitting elements made of LEDs are regularly arranged with the frame as a center. An illumination controller initializes the illumination, and corrects the illumination from the measured result. In order to automatically inspect the external appearance by using this apparatus, a DUT 20 of a VLSI, etc., is fixedly placed on a rotary stage 21 on a measuring base 22, rotated at 90 degrees at each one side measurement, and measured at the four sides. The camera 9 and the illuminator are oppositely disposed at a predetermined distance, and pixel data from the camera 9 is sent to an image processor 12. The processor 12 strengthens the light and shade of the density, displays it in a window as image data on a display unit 18, and decides the propriety, etc., of a lead pin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminator used at the time of visual inspection of a device and an automatic device visual inspection apparatus using the illuminator, which is particularly used at the time of visual inspection of a surface mounting LSI (high density integrated circuit). The present invention relates to an illuminator and a device appearance automatic inspection device. This illuminator is used both during visual inspection by humans and during inspection by an automatic inspection apparatus having an image processing unit. In this specification, the device appearance automatic inspection apparatus will be mainly described.

[0002]

2. Description of the Related Art Conventionally, the illumination used in the visual inspection of the device is an illumination which makes the entire DUT (Device Under Test) to be measured a constant brightness. Therefore, constant illumination is performed by a light source from above or obliquely above or from the side. In the conventional device, the number of input / output pins of the device was small, and the pin interval was relatively wide. Therefore, the above constant illumination was sufficient for both visual inspection and automatic inspection.

The automatic appearance inspection apparatus generally has an image processing unit conforming to the image processing apparatus. FIG. 5 shows an example of a flow chart of image data in the image processing apparatus. In the camera unit 50, for example, an image captured by the camera is converted into digital pixel data having a total of 302,000 pixels with 624 pixels on the horizontal axis and 484 pixels on the vertical axis for processing. The pixel data can be directly stored in the image memory 51,
The image is stored in the image memory 51 through the T (Look Up Table) 53. The LUT 53 is a conversion table for selecting a color to be displayed on the TV monitor 18 or the like, and is a memory in which the value of input data is used as its address and output data corresponding to the input data is written in advance. The data conversion function of the LUT 53 is used to perform binarization, preprocessing of grayscale images, conversion processing of display images, and the like.

The filter 52 has a function of emphasizing the edge of the DUT to be measured and pre-processing it when the periphery of the DUT is blurred, for example. The window memory 55 is a memory used to draw a window on the screen of the TV monitor 18. The graphic memory 56 is a memory for graphically displaying the measurement result and used as a work area. The character memory 57 is a memory that mainly displays characters, and is also used for editing a program, displaying a counting result, and the like.

The display control unit 54 is a control unit for processing the pixel data from the camera unit 50 directly or via the image memory 51 to display the image on the TV monitor 18. At this time, depending on the command, the window memory 55, the graphic memory 56 or the character memory 57.
Display using the data of. Even in the device appearance automatic inspection apparatus by the image processing apparatus using such a camera, it is possible in the conventional device by automatically adjusting the brightness with constant illumination.

[0006]

However, due to recent market demands, downsizing of equipment and high-density mounting of components have been advanced, and the number of surface-mount packages of devices has increased. Especially in the QFP (Quad Flat Package) of VLSI, the vertical and horizontal dimensions are from 10 mm × 10 mm to 30 mm.
The lead pins are arranged on four sides with a size of 30 mm, and the number of lead pins on one side is extremely large, from 8 to 76.
The lead pitch width is very narrow, 0.3 mm to 0.8 mm, and the thickness is about 2 mm to 10 mm.

These QFP and SOP (Small Alignmen)
Since the surface mounting package such as t Package) is directly soldered to the surface of the printed wiring board, its base must be flat and the lead pitch width must be constant. For such a fine and precise appearance inspection, the conventional constant illumination is not sufficient, and fine illumination has been required. This is because accurate measurement is required even if there is a difference in the light reflection status of the lead pin.

[0008]

To achieve the above object, the present invention provides a camera or an illuminating frame having a window frame of the line of sight in the central portion, and a large number of light emitting elements inside the illuminating frame. Arrange and illuminate the DUT. At this time, if there is unevenness in the overall illumination, the brightness of each light emitting element is adjusted to eliminate the unevenness. Brightness adjustment includes turning on and off. It can be done manually or automatically. Depending on the DUT, if the illumination from the lower side reflects the measured portion better, the upper light emitting element is turned off and only the lower light emitting element is turned on. The opposite case is also possible. This will be described in detail below.

It is preferable that the illumination frame be a horizontally long rectangle if the DUT is horizontally long, and a vertically long rectangle if the DUT is vertically long, and a similar quadrangle. This is because the lighting is spread over the entire surface of the DUT. The window frame at the center may be a line of sight or a lens of a camera. The size depends on the size of the DUT.

The light emitting element is an LED (Light Emitting Diode).
Any small object such as e), a fluorescent tube or a white lamp may be used. The light emitting elements are arranged in a certain range of the illumination frame. When the arrangement is regular in rows and columns, the uniformity of illumination can be obtained and the control is easy. In the case of a DUT having a specific property of reflecting light, it is advisable to change the number of light emitting elements vertically or horizontally. It is desirable that the brightness of each light emitting element can be adjusted by voltage or current.

The illumination control section for causing the above light emitting elements to emit light controls the brightness including turning on and off the individual light emitting elements. Initially, all the light emitting elements are turned on with the same brightness, and when there is unevenness in the luminous intensity on the surface to be measured, the emission brightness is controlled in row units, column units, or block units to eliminate the unevenness. The block is composed of a plurality of light emitting elements. Finally, each light emitting element may be individually controlled. This control can be active or automatic. In the case of automatic, a certain control sequence
It is good to do it with a can and stop at the optimum value. The lighting control unit may be provided adjacent to the lighting frame or may be installed at another place. In this way, it is an illuminator that can provide uniform illumination and can also provide strong illumination to a specific position. Next, the device appearance automatic inspection apparatus will be described.

The camera is a CCD (Charge Coupled Device)
) A camera is preferable. A / D (analog / digital)
This is because the conversion is easy, but it is possible with a general camera. A / D conversion is preferably performed in the camera. High sensitivity is desired. This is because we want to clearly capture the light and darkness of light reflection. Then, the lens of the camera is installed facing the DUT in the window frame in the center of the illumination frame.

The image processing unit processes the pixel data obtained by the camera. The image processing unit may be a conventional image processing apparatus, but it is better to install the illumination control unit inside. This is because the illumination is controlled by the image data processed by the image processing unit and the calculation data by the calculation processing unit. The arithmetic processing unit performs various arithmetic processing based on the image data and outputs the result.
The image data and, if necessary, the data of the arithmetic processing result are displayed on the TV.
Send to monitor. The TV monitor displays the DUT image. The arithmetic processing unit and the image processing unit perform various measurements according to the initially set measurement items, output the results from the measurement result output terminal, and display and print. T as described above
Also displayed on the V monitor. The measurement items differ depending on the DUT to be measured, but in the above-described QFP LSI, for example, the number of lead pins, the lead pitch width, the flatness of the lead pins, and the like are used. Examples will be described below.

[0014]

FIG. 1 is a perspective view of an embodiment of a device appearance inspection illuminator of the present invention, and FIG. 2 is a block diagram of an embodiment of a device appearance automatic inspection apparatus using this illuminator. The DUT to be measured is the above-mentioned QFP VLSI, and particularly the lead pin is measured. First, the illuminator for device visual inspection will be described with reference to FIG. Reference numeral 10 is a frame for illumination. There is a window frame for the camera 9 at the center of the quadrilateral illumination frame 10, and many light emitting elements 19 are arranged around this window frame. The lighting frame 10 is
Since the DUT 20 is horizontally long, it has a horizontally long rectangular shape.

An LED light emitting element is used as the light emitting element 19,
The rows and columns are regularly arranged, and the upper side is thinned out. It is easier to control the brightness when arranged regularly, and the number of the light emitting elements 19 near the upper side is reduced in this embodiment.
This is because it is easier to inspect if it is irradiated on the skin. Thus, the light emitting elements 19 may be arranged in consideration of the DUT 20. Since the brightness of one LED is approximately 2000 mcd (millimeter candela), the number of LEDs may be determined in consideration of the size of the DUT 20, distance, test items, test accuracy, and the like. Usually, 40 to 60 is sufficient. The emission color should be a color with good camera sensitivity.

Reference numeral 11 denotes a lighting control unit, which performs initial setting of lighting and correction of lighting based on measurement results. In other words, in the initial setting, a calibration target is placed at a certain measurement position in front of the illuminator to illuminate, and if the image is good, the value is set to the optimum value, and if bad, each light emitting element is set at a predetermined constant sequence. The control is performed to adjust the brightness including turning off and turning on and stop at the optimum value. This is an illuminator that can also perform readjustment control so that measurement can be performed each time a problem occurs in the measurement result of each DUT 20.

Next, a device appearance automatic inspection apparatus using this illuminator will be described with reference to FIG. DUT20
Is fixed on the rotary stage 21 on the measuring table 22. Since the DUT 20 is a QFP LSI and the lead pins 25 are provided on all four sides, it is necessary to measure all four sides.
The rotary stage 21 rotates 90 degrees for each side measurement and measures four sides.

The camera 9 and the illuminator are opposed to the DUT 20 and are installed at a fixed distance. The illuminator appropriately illuminates the DUT 20 as described above, and the camera 9 sends the pixel data to the image processing unit 12. Camera 9 is C
CD camera, A / D conversion immediately, 484 x 6
Pixel data of 24 points is obtained. Distance resolution is camera 9 and D
If the distance to the UT 20 and the magnification of the lens are appropriately selected, for example, if the 10 mm interval of the DUT 20 is imaged with 100 pixels,
A resolution of 0.1 mm / pixel is obtained. That is, the DUT 20 can be visually inspected at intervals of 0.1 mm.

The image processing unit 12 processes the pixel data sent from the camera 9 so as to increase the density of the image. This process facilitates the determination of the measurement position.
An example will be described with reference to FIG. 20 is a DUT, 25 is a non-defective lead pin, and 26 is a defective lead pin. In the lateral view of the good lead pin 25 shown in FIG. 3A, the bottom is flat, and this front view is shown in FIG. 3B. When the illumination is strongly radiated from slightly below, strong reflected light enters the camera 9 from the tip of the lead pin 25, and is displayed in black and clear on the TV monitor 18. The width of the lead pin 25 is obtained from the number of pixels in this black portion, and the position of the center point thereof is also obtained. Although not shown in FIG. 3, the distance between adjacent lead pins, that is, the lead pitch width is also obtained.

FIG. 3C shows an example of the defective lead pin 26. The tip is bent and slightly upward and not flat. This front view is as shown in FIG. 3D, and the reflected light from the tip of the defective lead pin 26 does not enter the camera 9 and the TV monitor 18
Is displayed in white. Therefore, the position cannot be determined. Therefore, it is judged as a defective product, but there is still a case where the user wants to know the position. At this time, the illumination control unit 11 is driven to slightly intensify the illumination from above. Therefore, strong reflected light is incident on the camera 9, and the tip position of the defective lead pin 26 is also confirmed in the image processing unit 12. The flatness (step) with respect to the position of the good lead pin 25 is also required.

The image processing unit 12 processes the pixel data from the camera 9 as the image data as described above to emphasize the shading, to change an arbitrary measuring unit to an arbitrary color display through the LUT 53, and to display a window display. An image is displayed on the TV monitor 18 by displaying or displaying characters. The arithmetic processing unit 14 determines whether the lead pin 25 is good or bad, and measures the lead pin width, the lead pitch width, and the flatness (step) based on this image data. TV calculation result
It is displayed on the monitor 18 or output from the measurement result output terminal 16 to the outside.

In addition, the measurement processing unit 14 that also controls the entire system from the setting input terminal 15 for the measurement item and the procedure of the processing method
To enter. There are setting buttons and
You may provide a key and input from here. It is more convenient to provide the illumination control unit 11 in the arithmetic processing unit 14 as well.

FIG. 4 shows a DUT having a poor appearance particularly in the measurement procedure.
6 is a flowchart of an example of the case. The DUT 20 is fixed on the rotary stage 21, and the measurement is started by the signal of the measurement start 30. If the preset measurement point, that is, whether all the pins have been measured, is Yes in the determination of 31, the DUT 20 outputs the measurement result 32 and ends 33. If NO, the illumination control unit 11 is driven to control the brightness of the light emitting element 19. For example, the lighting position of the LED is changed 34. And re-measured 35 for the pin that cannot be measured and measured 3
If the result of the determination in 6 is Yes, the measurement result is output 32 and the process ends 33. If No, it returns to changing the lighting position of the LED of 34 again, and remeasurement 35 is performed. This remeasurement is, for example, 3
Up to three times, it is judged 38 whether it is larger or smaller than three times.

[0024]

As described above in detail, the present invention makes it possible to easily perform the visual inspection of a device which has been extremely miniaturized, highly accurate, and miniaturized in recent years. In the device visual inspection illuminator, a large number of light-emitting elements 19 whose brightness can be adjusted centered around a camera for observing the DUT 20 can be arranged, and the brightness of each light-emitting element 19 can be controlled by the observation result, so uneven illumination can be eliminated. Moreover, since irradiation from a specific direction can be easily performed, irradiation and observation of a specific portion of the DUT 20 can be correctly performed. It is an essential illuminator for observing minute parts.

In the device appearance automatic inspection apparatus using this illuminator, the illuminator capable of arbitrarily irradiating the measurement portion of the DUT 20 makes the contrast of the measurement portion imaged by the camera clear and facilitates automatic measurement. Further, by increasing the number of pixels of the image data, the distance resolution can be set to 0.1 mm / pixel or less, and ultra-precision measurement can be performed. As described above, the present invention is most suitable for the miniaturized appearance inspection of the device,
Its technical effect is great.

[Brief description of drawings]

FIG. 1 is a perspective view of a device visual inspection illuminator that is an embodiment of the present invention.

FIG. 2 is a configuration diagram of a device appearance automatic inspection apparatus according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of lead pins of a QFP that is a DUT.

FIG. 4 is a flow chart of an example of the measuring method of the present invention.

FIG. 5 is a flowchart of an example of image data in the image processing device.

[Explanation of symbols]

 9 camera 10 lighting frame 11 lighting control unit 12 image processing unit 13a pixel data input terminal 13b illuminator control data output terminal 14 arithmetic processing unit 15 setting input terminal 16 measurement result output terminal 17 TV image output terminal 18 TV monitor 19 light emission Element 20 Measured DUT 21 Rotary stage 22 Measuring stand 25 Good lead pin 26 Bad lead pin

Claims (3)

[Claims] 1. An illumination frame (10) having a window frame into which a lens of a camera (9) is inserted in a central part, and arranged inside the illumination frame (10) at regular intervals in row and column directions. An illuminator for inspecting a device appearance, comprising: a plurality of light emitting elements (19) that are provided; and an illumination control unit (11) that controls the brightness of any of the light emitting elements (19). 2. The illuminator for device visual inspection according to claim 1, wherein the plurality of light emitting elements are LED light emitting elements. 3. A device appearance inspection illuminator according to claim 1, a camera (9) for photographing a DUT (20) to be measured, and pixel data from the camera (9) are input and processed into image data. Image processing unit (12) to perform, and DUT (20) measured according to the set inspection item
A device appearance automatic inspection, comprising: an arithmetic processing unit (14) for measuring the appearance of the device; and a TV monitor (18) for inputting image data from the image processing unit (12) and displaying an image. apparatus.