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SPI stands for Solder Paste Inspection. SPI equipment is usually referred to as inline solder paste inspection equipment in the SMT industry, which is used to inspect the height, volume, area, short circuit and offset of solder paste after printing. There are currently two types of SPI equipment: offline and inline.
Many of the causes of PCBA manufacturing defects are caused by the printing of solder paste, in order to better control the quality of the printed solder paste, the PCBA industry has given birth to SPI. 80% of the defects in the PCBA process are caused in the printing process, with more and more mounted parts to do more and more sophisticated, smaller and smaller sizes, high-density BGAs, QFNs, connectors, 0201 and the following materials are commonly used, the solder paste is more and more difficult to detect. With more and more precision of mounting parts, smaller and smaller size, high density BGA, QFN, connectors, 0201 and the following materials are commonly used, the quality control of solder paste printing becomes more important, and the inspection becomes more difficult and more complex. SPI equipment is also widely used in SMT production lines to replace the original manual inspection.
1.SPI is generally placed after the SMT solder paste printing machine, when the PCB solder paste printing is completed through the track transfer to the SPI internal inspection,so can this improve the SMT yield? The answer is yes. The more important thing is how to use SPI to screen out the PCB boards with bad printing solder paste, and then trace why the printing solder paste is bad, so as to solve the fundamental problem.
2.Due to the precision and miniaturisation of electronic products nowadays, the precision of many electronic components processed by SMT is quite high, so the quality of printed solder paste on the PCB surface is very high when the components are mounted. If you can detect the quality of solder paste printing before the piece, it will certainly be more effective than the piece after the reflow connection, because the bad PCBA board after the furnace in the maintenance process requires the use of iron or more complex tools for repair, a little inattention may be PCBA damage. Then have SPI inspection equipment SMT processing plant can avoid the occurrence of these problems.
3.SIP inspection includes: the amount of solder paste printing, the thickness of the solder paste printing, the area of the solder paste printing, the flatness of the solder paste printing, whether the solder paste printing is offset or not, whether the solder paste printing is sharp or not, whether the solder paste printing is tinned or not.
SPI Specific Inspection and Judgement Contents
SPI can measure the following data: the amount of solder paste printed, the height of solder paste printed, the area/volume of solder paste printed, and the flatness of solder paste printed.
Further, the data is used to determine whether the paste print is offset, whether the paste print is off-height (pulling tip), whether the paste print is bridged, and whether the paste print is defective, broken, or collapsed.
SPI can be used to correctly screen out the boards with bad solder paste printing, and then trace back to the boards with bad solder paste printing to improve the yield of SMT soldering.
SPI programming and usage steps
1.Select New Programme and adjust the width of PCB, put the PCB into the board and set the lower left corner of the PCB as the origin and the upper right corner as the maximum range setting point.
2. Import the gerber file returned from the stencil factory, delete the unwanted components in the gerber interface, then import the gerber and set the MAKE point.
3.Calibrate the MAKE point, set the light source, and get the pink colour under the MAKE picture.
4.Set the templates of PCB, solder paste and pads, and adjust the colours. In the 3D picture, the solder paste area is pink, and the rest of the silkscreen layer is other colours, that is OK. Save it and start the test.
5.Open the debugging window, set a reasonable range of deviation according to the actual situation after the test. In order to ensure the efficiency and convenience of the test, in the case of quality assurance to increase the range of error, reduce the number of false reports NG. In the test of printing unacceptable defects can be completely exposed, the test results reported NG that is qualified.
Advantages of SPI
1.Reduce defects: SPI is firstly used to reduce defects caused by improper printing of solder paste. In this case, the primary advantage of SPI is its ability to reduce defects.
2.High efficiency: With SPI, defects can be detected at the SMT printing stage right after solder paste printing. Once an incorrectly printed solder paste is detected, it can be reworked immediately to obtain high quality solder paste printing. More time will be saved.
3.Cost reduction: Defects found in the pre-SMT printing stage can be reworked in a timely manner to intercept the defects and prohibit them from flowing into the next process, thus improving the throughput rate of the product and reducing the maintenance time and quality risk.
SPI is a means of quality control in the SMT processing process, the use of good can effectively improve product quality, thereby reducing manufacturing costs. If SPI is just an arrangement of PCBA manufacturing, then SPI will only affect the production efficiency, SPI alarms must be investigated PCB printing solder paste quality, to control the defective rate to the minimum. SPI in SMT processing is not only to prevent the quality of solder paste printing, but more importantly, to control and prevent the maintenance cost in the future, which helps to increase production capacity and new profits. With the sophistication of electronic products, the quality of printed solder paste is becoming more and more important. SPI is able to effectively ensure good solder paste printing quality and significantly reduce the possible PCBA quality risks.