JPS63103948A - Detecting method for external lead of resin sealed type semiconductor device - Google Patents

Abstract

PURPOSE:To speed up measuring operation and make a measurement level quantitative by providing a CCD sensor on a straight line connecting a light source which emits light to a through hole bored in a support base and an external lead. CONSTITUTION:A resin sealed type semiconductor device 1 is constituted by providing a nearly flat sealing resin layer 2 to as to protect a semiconductor element from an external atmosphere and leading plural external leads 3 for connecting with the semiconductor element electrically from the flank of the layer in the same direction. The outward appearance is inspected while plural semiconductor devices 1 are mounted on the support base 6. Namely, the through hole 9 is bored in the support base 6 where the external leads 3 led out of the flank of the flat sealing resin layer 2 are projected, and the CCD sensor 11 is provided on the straight line connecting the light source 10 which emits the light to the through hole 9 and the external leads 3, so that transmitted light from the light source 10 is made incident on it. Thus, the semipermanent- life and maintenance-free CCD sensor is utilized and the advantage of small image distortion at the periphery and in the center is utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention is suitable for visual inspection to check for defects, lead bends, etc. occurring in external leads of resin-sealed semiconductor devices.

(Prior technology) In the harsh environment surrounding semiconductors, there is a need to establish highly productive manufacturing lines, and as a part of this, the size of semiconductor wafers is also increasing in diameter.
It is now possible to pull the above semiconductor single crystal.

As semiconductor wafers become larger in diameter, manual handling of semiconductor wafers becomes difficult, and automation is inevitably required for their transportation and setting into manufacturing equipment. On the other hand, recent semiconductor devices, as typified by VLSI, have made remarkable progress in becoming highly integrated and highly functional.
As a result, manufacturing processes have become more complex and diverse.
The cleanliness of production lines has an increasing influence on production yields, automation is being promoted in all aspects to keep the human body away from the source of dust, and many models are being put into practical use.

As part of this effort, a device 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 converts image signals obtained by a TV camera into binary images at a constant slice level to inspect the appearance of resin-sealed semiconductor devices for cavities, chips, scratches, bent leads, lead lengths, etc. It uses a visual sensor application device that has a built-in dedicated processor and minicomputer necessary for image processing and can produce high-speed images.

For this purpose, a method using pattern recognition technology can be considered, but the error limit is 3 to 4%, so it is not suitable for external inspection of semiconductor devices, which requires an error limit of 0.1% or less for minute appearance defects. It is inappropriate for now.

(Problems to be solved by the invention) Appropriate illumination is required to image a resin-sealed semiconductor device to be inspected with an ITV camera, and depending on the surface condition of the object, uniform brightness within the surface may not be achieved. It turns out that it is not possible to obtain a binarized image, thus creating a problem in obtaining a binarized image.

When examining the distribution state of regular reflection lighting and ring lighting, which are the lighting means, with constant lighting conditions, not only do they vary within the plane, but also the brightness level differs for each subject. Furthermore, it was also found that with ring lighting, although the brightness level differs for each subject, the in-plane variation is smaller than the former.

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

The present invention relates to a novel visual inspection method for resin-sealed semiconductor devices that overcomes this difficulty, and particularly aims to reduce costs by using a simpler method.

[Structure of the invention]

(Means for solving the problem) In a resin-sealed semiconductor device, a substantially flat sealing resin layer is provided to protect the semiconductor element from the external atmosphere, and the semiconductor element is electrically connected to the side surface of the sealing resin layer. A plurality of leads are aligned in the same direction and derived. In the present invention, this visual inspection of the leads can be carried out using a convenient method, and this visual inspection is carried out with a plurality of resin-sealed semiconductor devices housed in a tray (hereinafter referred to as a support stand). implement. In other words, a through hole is provided in the support base onto which the lead leading out from the side surface of the flat sealing resin layer is projected, and a CCD sensor is placed at a position where this lead is linearly connected to a light source that enters light into the second through hole. Visual inspection is performed by providing a saw with transmitted light from a light source incident on the saw.

(Function) CCD with semi-permanent life and maintenance-free
In the present invention, a line sensor is used, and further consideration is given to taking advantage of the advantage of low image distortion in the periphery and center.

This is because recent resin-encapsulated semiconductor devices sometimes use a method in which the leads are coated with a solder layer using a so-called dipping method to ensure a secure connection with the equipment being used. The solder layer swells to form a quadratic curved surface. For second imaging, image distortion in the periphery and center is small C
A CD line sensor is suitable, and this CCD line sensor uses a method in which a lead is connected to a light source and transmitted light is incident.

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

As shown in FIG. 3, a resin-encapsulated semiconductor device [1] is a semiconductor pellet (not shown) in which a functional element such as an IC is embedded inside a substantially flat encapsulating resin layer 2, and its electrodes and The electrically connected external leads 3 are led out of the sealing resin. This derivation is the side surface 4 of the flat sealing resin M2...
・It is made up of external lead rows 5 that are neatly bent in the same direction.

The appearance of such a resin-sealed semiconductor device is inspected by placing it on a support stand 6 shown in FIG. Moreover, since the light transmitting elements 9 are formed at the positions where the lead arrays 5 are projected, the lead arrays 8 of the resin-sealed semiconductor device 1iW1 can be seen through from the thickness direction of the support base 6. The light transmitting element 9 has dimensions of 20 x 2 mm or 14 x 2 mN degrees.

On the other hand, as shown in FIG. 1, a light source lO and a COD sensor 11 are installed with this support stand 6 as a boundary.

A straight tube fluorescent lamp is preferably used as the light source for conveniently illuminating the lead row 8, and a CCD line sensor is arranged as the sensor. In Fig. 1, the light source 10 is supported by the support stand 6.
Although the CCD line sensor 11 is placed on the lower side and the CCD line sensor 11 is placed on the upper side, the opposite may be used. The installation position of the straight tube fluorescent lamp 10 is set at the center of the support base 6 so that the brightness in the lead rows 8 . . . is uniform.

In such a positional relationship, the light source 10 and the external lead array 8 are connected on a - straight line, so that transmitted light is incident on the CCD line sensor 11, making it possible to perform an appearance inspection of this external lead. become. Specifically, by finding the difference in the interval pip between the external leads 3 and the difference in the total length QiQ2 between the external leads 3 and the bent part shown in Fig. 3, the lead bending and the number of leads can be determined from the standard values. By comparison, H1'l can be determined. Of course, a dedicated processor and minicomputer are used as accessory equipment.

The sealing toughness layer 2 is a so-called QFP (Quad
A square or rectangular shape such as a flat package (Flat Package) can also be applied, and the dimensions of the transparent light 9 provided on the support stand 6 are such that the pitch between the recesses 7 is The total length of the external lead led out from the sealing resin layer 2 is about 2.8 m, and the length of the external lead that protrudes after being bent is about 1.7 am.

[Effects of the Invention] As described above, the present invention applies a CCD line sensor that has a semi-permanent life and is maintenance-free, and provides a central and The advantage of low peripheral image distortion is skillfully applied.
Furthermore, it is possible to perform visual inspection of the external lead array led out from the side surface of the sealing resin layer using a single light source, which speeds up the measurement and quantifies the measurement level, improving the quality of the semiconductor device. It also becomes possible.

There is also the advantage that the inevitable troubles that occur when using a plurality of light sources can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an outline of the detection method according to the present invention.
The figure is a sectional view showing the main parts of a device employing this method. FIG. 3 is a perspective view of a resin-sealed semiconductor device.

Claims (1)

[Claims] A substantially flat encapsulation resin layer, a semiconductor element embedded in the encapsulation resin layer, and a plurality of external leads that are aligned and led out in the same direction from a side surface of the encapsulation resin layer and electrically connected to the semiconductor element. , a support base having a concave portion for accommodating the sealing resin layer; a light transmission provided on the support base onto which the plurality of external leads are projected that are engaged with the concave portion; and a light source that enters light into the through hole; A method for detecting external leads of a resin-sealed semiconductor device, comprising the light source and a CCD sensor that receives transmitted light that connects the external leads.