JPS63107034A - Detection system for outer lead for semiconductor device - Google Patents

Abstract

PURPOSE:To make compact a device while improving the reliability of detection by reflecting beams by an optical mirror from a tubular light source and projecting the reflected beams to CCD line sensors oppositely arranged to each outer lead row as transmitted beams. CONSTITUTION:A plurality of outer leads 5 to be measured, which are aligned in the same direction from opposed side surfaces in an approximately flat resin sealing layer 2, into which a semiconductor chip is buried, and lead out, are fixed by a positioning mechanism 8 shaped at the position 7 of measurement set to a carrying system. A single tubular light source 13 is disposed along the outer lead rows 5 to be measured. Beams from the tubular light source 13 are reflected by mirrors 15 shaped to the carrying system positioned between the outer lead rows 5 to be measured, and transmitted beams are projected to CCD line sensors 14 oppositely mounted to each row of the outer leads 5 to be measured. A straight pipe type fluorescent lamp 13 having a diameter such as approximately 10mm is arranged to a lower part between the outer leads 5, 5 as said tubular light source 13.

Description

DETAILED DESCRIPTION OF THE INVENTION <Object of the Invention> (Industrial Field of Application) The present invention relates to the visual inspection of resin-sealed semiconductor devices, and is particularly suitable for checking the bending of external leads and detecting the number of pins.

(Conventional technology) The harsh environment surrounding semiconductors requires the establishment of highly productive manufacturing lines, and as a link to this, the size of semiconductor wafers is trending toward larger diameters, and semiconductor single crystals have already been pulled. 200mmφ or more is possible.

As semiconductor wafers become larger in diameter, it becomes difficult to handle them manually, and automation is inevitably required for the transportation and setting of semiconductor wafers in manufacturing equipment. On the other hand, recent semiconductor devices, as typified by VLSI, have made remarkable progress in becoming highly integrated and high-performance, and as a result, manufacturing processes have become more complex and diverse, and the cleanliness of the manufacturing line has an impact on manufacturing yield. The impact is significant, and from the perspective of keeping the human body, the source of dust, away, automation has been promoted across the board, and many models have already been put into practical use.

As part of this effort, an apparatus for automatically inspecting the appearance of semiconductor devices, particularly resin-sealed semiconductor devices, has been developed and has already entered the stage of practical use. This equipment uses image signals obtained from an industrial ITV camera to inspect resin-sealed semiconductor devices to be inspected for their external appearance, such as cavities, chips, scratches, lead bends, lead lengths, etc. The visual inspection is performed by converting the image into a binary image at a fixed slice level.

Of course, this device uses a dedicated processor necessary for image processing and a visual sensor application device that incorporates a minicomputer and IQ to perform image processing at high speed.

For this purpose, a method using pattern recognition technology can be considered, but since the error limit is 3 to 4%, it is difficult to aim for minute appearance defects such as semiconductor devices, that is, an error limit of 0.1% or less. It's inappropriate.

<Problems to be solved by the invention> Appropriate illumination is required to image the aforementioned resin-sealed semiconductor device to be inspected with an ITV camera, but uniform brightness within the plane may not be achieved depending on the surface condition of the object. It turns out that this is not possible, and therefore there is a problem in obtaining a binarized image.

When we investigated the distribution of specular reflection lighting and ring lighting, which are the lighting means, with constant lighting conditions, we found that not only were there variations within the plane, but also the brightness levels were different for each subject. Furthermore, although the brightness level of ring illumination similarly differs depending on the subject, it has been found that the in-plane variation is smaller than the former.

Therefore, if there are portions with different brightness on the inspection surface of the resin-sealed semiconductor device that is the subject, there is a problem in that the fidelity of the image obtained by binarizing at a certain slice level is impaired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new semiconductor external lead inspection method that eliminates the above-mentioned difficulties.

<Structure of the Invention> (Means for Solving the Problems) The present invention provides a plurality of external parts that are aligned in the same direction and led out from opposing sides of a substantially flat encapsulating resin layer of a resin-encapsulated semiconductor device. A lead array is the object to be measured, and the external leads to be measured are fixed to the transport system by a positioning mechanism provided near a measurement position set in the transport system for the resin-sealed semiconductor device. A mirror is formed in the transport system located between the rows of external leads to be measured, and reflects the light from a single tubular light source placed along this row of external leads, and is also placed opposite to this row of external leads. We adopted a method in which this transmitted light is incident on a CCD line sensor.

(Function) In this way, we have used a CCD line sensor that has a semi-permanent life and is maintenance-free, and have also taken advantage of its advantage of low image distortion in the periphery and center. This is because the outer leads of recent resin-sealed semiconductor devices are coated with a solder layer using a so-called dipping method to ensure connection with other devices, and for this reason, the outer lead circumference is The solder layer often builds up on the surface to form a quadratic curved surface. For this imaging, a CCD with small image distortion in the periphery and center is used.
It is appropriate to use a line sensor, and two rows of external leads can be measured simultaneously by simply arranging a single tubular light source. In other words, the light emitted from the tubular light source is reflected by a mirror and is disposed facing each external lead row.
The light enters the CD line sensor as transmitted light. This results in stabilization of the test, which in turn improves reliability.

(Example) The present invention will be explained in detail with reference to FIGS. 1 to 4.

Resin-encapsulated semiconductor device I! As shown in Fig. 1, a semiconductor pellet (not shown) in which functional elements such as ICs are embedded is embedded inside a nearly flat sealing resin layer 2, and an external electrode is electrically connected to the electrode. Leads 3... are guided out of this sealing resin. When deriving it, the flat sealing resin layer 2 is neatly bent in the same direction from opposite sides 4, 4.
Two external lead rows 5 are formed in parallel relationship. Such a resin-sealed semiconductor device is moved to a predetermined position, that is, a measurement position 7 set in the transport system by a transport system 6 shown in FIG. At this measurement position 7, the external lead array 5.5 to be measured on the transported resin-sealed semiconductor device rIL is fixed by a positioning mechanism. The transport system 6 constituting the measurement position 7 is provided with a thin section 12 to prevent the tips of the external lead array 5 from coming out of the field of view of the CCD line sensor, which will be described later. 9. There is a mechanism 11 that performs the stopper IO and the vertical positioning. All of these use air cylinders.

The kicker 9 utilizes its rotation locus, and the upper and lower positioning mechanisms 11 eliminate slight gaps that occur when moving in the transport system 6 to ensure positioning. This external lead row 5
, 5, a straight tube fluorescent lamp 13 with a diameter of about 10 m5 is arranged as shown in Figs. do. Furthermore, a lens 15 is fixed to the thin wall portion 12 of the transport system 6 at the measurement position 7 to reflect the emitted light from this tubular light source (FIG. 1), and direct the transmitted light to the CCD line facing the external lead array 5.5. The light enters the sensor 14.14 for detection.

For the external lead rows 5 and 5 located between this lens and the optical axis of the CCD line sensor, the difference in Ql (1) and the difference in plp shown in Fig. 3 are determined, and a quality judgment is made by comparing this with a standard value. Therefore, a dedicated processor and a minicomputer are used as accessory equipment for this image processing-based determination.

Since it is difficult to place the tubular light source 13 between the external lead rows, a location below the external lead rows is selected.

<Effects of the Invention> As described above, the method for detecting external leads of a semiconductor device according to the present invention has a semi-permanent life and is maintenance-free.
By applying the D sensor, the advantage of small image distortion in the center and periphery, which is convenient for detecting quadratic curved surfaces due to the solder layer raised on the peripheral surface of the external lead, is skillfully utilized. In addition, the two external rows formed on the resin-sealed semiconductor device, which is the object to be measured, can be measured simultaneously at the same measurement position set in the transport system, making the device more compact and capable of detecting The reliability of the index is improved and the index is also reduced. By using a single measurement position, not only the speed can be increased, but also the measurement level can be quantified, so it is also possible to improve the quality of the semiconductor device. In the present invention, since it is sufficient to use a hollow tubular light source, various problems that occur when using a plurality of light sources can be omitted.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an overview of the method of the present invention, FIG. 2 is a cross-sectional view showing the main parts of a device to which this method is applied, FIG. The figure is a perspective view of a resin-sealed semiconductor device.

Claims (1)

[Claims] A plurality of external leads to be measured are aligned and led out in the same direction from opposite sides of a nearly flat resin sealing layer in which a semiconductor chip is embedded, and are fixed by a positioning mechanism formed at a measurement position set in the transport system. A single tubular light source is arranged along this row of external leads to be measured, and a mirror formed in the transport system located between the external leads to be measured reflects the light from the tubular light source. A detection method for semiconductor external leads characterized in that transmitted light is incident on a CCD placed opposite each row of external leads to be measured.