Machine vision inspection technology: About chip appearance defect detection

Date：2021-06-08 17:31:37 Views：2450

With the continuous innovation of chip technology and chip packaging technology, the chip area and packaging area are developing towards smaller, lighter and thinner, the number of pins is increasing, the pin spacing is decreasing, and the difficulty of chip appearance detection is also increasing. The traditional manual detection method has been difficult to meet the high requirements of detection and can not adapt to mass production. The machine vision detection of chip appearance defects has incomparable advantages with manual detection: fast detection speed, high detection accuracy, high detection efficiency, low misjudgment rate, more objective and reliable, and non-contact detection will not cause contact damage to the chip.

Visual inspection system generally includes industrial camera, light source, lens and visual software. It can replace artificial and is equivalent to the eyes of robot. Generally speaking, it is image processing. The objects and areas to be detected are photographed by the camera, and then the image is processed. In theory, machine vision is to use machines instead of human eyes and brain to identify, detect and judge. Machine vision system refers to converting the captured target into image signal through machine vision products (camera, lens and light source), which is transmitted to the computer and transformed into digital signal according to pixel distribution, brightness, color and other information; Then cooperate with appropriate image processing software to identify and detect the image, output various signals, and give the signal of equipment action.

Contents of chip appearance defect detection:

Chip appearance defects mainly include three aspects. Machine vision detection equipment can detect these problems.

1. Defect detection of chip package, such as scratch, stain, damage, underfilling, overflow, etc.

2. Printing defect detection, such as misprint, offset, missing print, overprint, blur, tilt, displacement, hyphenation, double-layer printing, wordless die, etc.

3. Pin defect detection, such as pin missing, pin damage, pin spacing, pin width, pin bending, pin span, pin length difference, pin standing height, pin coplanarity, pin inclination, etc

The main working process of a complete machine vision inspection is as follows:

(1) The workpiece positioning detector detects that the object has moved close to the center of the camera field of view, and sends a trigger pulse to the image acquisition card;

(2) The image acquisition card sends start pulses to the camera and lighting equipment respectively according to the preset program and time delay;

(3) The camera stops the current scanning and starts a new frame scanning again; Or the camera is in a waiting state before the start pulse arrives, and starts a frame scan after the start pulse arrives;

(4) Before the camera starts a new frame scanning, open the exposure mechanism, and the exposure time can be set in advance;

(5) Another start pulse turns on the light, and the light on time shall match the camera exposure time;

(6) After the camera is exposed, the scanning and output of a frame of image are officially started;

(7) The image acquisition card receives the analog video signal and digitizes it through a / D, or directly receives the digital video digitized by the camera;

(8) The image acquisition card puts the digital image into the memory of the processor or computer;

(9) The processor processes, analyzes and recognizes the image to obtain the measurement result or logic control value;

(10) The processing result controls the action of the pipeline; Or positioning, correcting motion errors, etc.

The above is the related content of "chip appearance inspection". Through this paper, I hope you have a certain understanding of machine vision inspection and chip appearance inspection. In fact, machine vision system has penetrated into all aspects of our life, production and work, and has been widely used in industry, agriculture, national defense, transportation, medical treatment, finance, sports, entertainment and so on.