What can the solder paste tester do

PCB problem What can the SPI (Solder Paste Inspection) solder paste inspection machine do?

SPI is the abbreviation of Solder Paste Inspection, whICh is calLED Solder Paste Inspection in Chinese. If it is a solder paste inspection machine, it is OK to add an English word Machine. But in most cases, you can know that you are talking about the solder paste inspection machine as long as you talk about SPI with the other party.

What's the use of SPI (Solder Paste Inspection)? What inspection can we do? Why are more and more SMT production lines equipped with SPI equipment?

80% of the defects in SMT process come from improper solder paste printing.

If the working bear tells you that about 80% of the defective rate of SMT processing is due to improper printing of solder paste, then you think that setting a "solder paste inspection (SPI)" level after the solder paste printing/before the placement, and brushing off the boards with defective solder paste printing before the printing, can you improve the yield of SMT welding? The answer should be yes. The key point is how to use the solder paste inspection machine to correctly screen out the boards with solder paste printing defects, and then track forward why solder paste printing defects occur.

In particular, there are more and more parts below 0201 or bottom welding parts such as BGA, which are very sensitive to the quality of solder paste printing. If the board with solder paste printing problems can be detected before passing the furnace, it will be more effective and cost saving than if it is detected after reflow welding is completed. Because the maintenance of the board behind the furnace usually requires moving a soldering iron or complex maintenance tools, and it may also damage the board.

This "solder paste inspection machine" is actually SIMilar to the AOI (Auto Optical Inspection) optical identification system device commonly placed behind the SMT furnace. It also uses optical images to check the quality. The difference is that the solder paste inspection machine has added a laser device for measuring the thickness of solder paste, so the problems that the SPI may encounter are similar to those of AOI, that is, first take a piece of panel for visual inspection, and then let the machine take a photo as a gold sample, The later boards are judged according to the image and data of the first board. Of course, there will be a lot of false positives. Therefore, its parameters must be constantly modified until the false positives are reduced to a certain level. Therefore, the SPI machine cannot be used after it is bought back, and engineers must be able to write programs and maintain it.

In addition, most solder paste inspection machines can eat Gerber and CAD, but there are usually some errors, which still need to be adjusted.

What is the capability of solder paste inspection machine? Which solder pastes can be checked for poor printing?

Ok, let's see what the Solder Paste Detector can do for us? It can also help us find out which defects of solder paste printing? Please note that the solder paste inspection machine can only perform image inspection of the surface. If there is an area covered by an object, it cannot be detected. However, the solder paste inspection machine should be used before the parts are placed, so there should be no solder paste covered.

The solder paste tester can measure the following data:

Solder paste printing quantity

Height of solder paste printing

Area/volume of solder paste printing

Flatness of solder paste printing

Make SPC statistics to measure the process capability

In addition, the solder paste tester can detect the following defects:

Offset of solder paste printing (shift)

Whether the solder paste printing height deviation (pulling point)

Bridge for solder paste printing

Whether solder paste printing is defective or damaged

Only a few devices are machines, and people are still the key. SPI is a set of tools that can help improve product quality, thereby increasing production capacity and reducing costs. If you just put them where they are and press them when they encounter an alarm, SPI will only affect the output.