3D SPI principle and detection metho

3D SPI principle and detection method

SPI (SolderPaste Inspection) refers to the solder paste detection system, the main function is to detect the quality of solder paste printing, including volume, area, height, XY offset, shape, bridge, etc. How quickly and accurately detect extremely small solder paste , The general use of PMP (Chinese translation for the phase modulation profile measurement technology) and Laser (Chinese translation for the laser triangulation technology) detection principle.

Laser triangulation technique

The detection light source is laser, the laser beam in different height plane distortion, the detection head in a certain direction of continuous movement, the camera according to set the time interval to take pictures, so as to obtain a set of laser distortion data, and then calculate the test results (As shown below)
Advantages: faster detection
Disadvantages: 1) laser resolution is low, generally only 10 - 20um level.
2) Single sampling, low repeatability accuracy.
3) Sampling in the movement, the external shock and transmission vibration on the detection of a greater impact.
4) laser monochromatic light on the PCB board color is weak.
Market conditions: laser technology has gradually withdrawn from the SPI industry. At present, South Korea Parmi is still using laser technology (dual laser technology)

PMP phase modulation contour measurement technology
1) Using a white light source, the solder paste is measured by the phase change of the structural grating
2) Using the grayscale change of the structural grating, a high accuracy is obtained
3) the use of phase changes, each solder paste for 8 times to ensure that the detection of high repeatability accuracy
4) PMP technology is divided into FOV walk-off and Scan scanning two detection methods

4.1 FOV stop
When the test is carried out, the motion is not sampled and does not move during sampling, and the effect of vibration on the detection is minimized.
Advantages: 1) PMP principle detection resolution is high, 0.37um.2) stable multi-sampling, detection repeatability is extremely high .3) on the PCB color is not critical.
Disadvantages: the speed is relatively slow.
Market: to stabilize the detection results identified by the industry as the best SPI solution to South Korea KohYoung as the representative of foreign brands.

4.2Scan Scanning
The phase change of the structural grating is formed by the continuous motion of the detecting head, while sampling is carried out while moving.
Advantages: 1) PMP principle detection resolution is high, 0.37um.2) on the PCB color is not critical .3) multiple sampling, detection repeatability than laser-type equipment .4) detection speed faster than FOV stop.
Disadvantages: the impact of external shocks, detection repeatability is low.
Market: China Taiwan TRI as the representative of the Chinese Taiwan brand, represented by the foreign brand of Cyber.