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

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

SPI is the abbreviation of [Solder Paste Inspection], and it is called [Solder Paste Inspection] in Chinese. If it is a solder paste inspection machine, add the English word Machine at the end, but in most cases, just talk to the other party about SPI. Talking about solder paste inspection machine.

What is the use of SPI (Solder Paste Inspection)? What kind of inspection can you do for us? Why are there more and more SMT production lines with SPI devices?

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

If the working bear tells you that about 80% of the defective rate of SMT processing comes from improper printing of solder paste, then you think that a "Solder Paste Inspection (SPI)" is set up after the solder paste is printed For checkpoints, the boards with poorly printed solder paste should be brushed off before the parts are printed. Can this improve the yield rate of SMT soldering? The answer should be yes, the key point is how to use the solder paste inspection machine to correctly screen out the boards with poor solder paste printing, and then go forward to track why the solder paste printing is defective.

Especially now there are more and more parts below 0201 or bottom soldering 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 the furnace, it will It is more effective and cost-effective than detecting after the reflow soldering is completed, because the repair of the board after the furnace usually requires a soldering iron or complicated repair tools, and the board may be damaged.

This "solder paste inspection machine" is actually similar to the AOI (Auto Optical Inspection) optical identification system device that we usually usually place behind the SMT furnace. It also uses optical images to check the quality. The difference is that the solder paste inspection machine has been added. A laser device for solder paste thickness measurement, so the problems that SPI may encounter are similar to those of AOI. First, take a piece of the jigsaw for visual inspection and then let the machine take a picture as a standard sample (Golden Sample). The image and data of a piece of board are used to make judgments. Of course, there will be a lot of misjudgment rate. Therefore, its parameters must be continuously modified until the misjudgment rate is reduced to a certain level. Therefore, it is not possible to buy the SPI machine and use it. There must also be an engineer who can write programs and maintain them.

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

What are the capabilities of the solder paste inspection machine? Can you check out those solder paste printing defects?

Okay, let’s see what the "Solder Paste Inspection Machine" can do for us? Can also help us check out the defects of solder paste printing? Please note that the solder paste inspection machine can only perform image inspection on the surface. If there is an area covered by an object, it cannot be inspected. However, the timing of the use of the solder paste inspection machine should be before the parts are placed, so it should be No solder paste will be covered.

The solder paste inspection machine can measure the following data:
Solder paste printing volume
Height of solder paste printing
Solder paste printing area/volume
Flatness of solder paste printing
Make SPC statistics to measure process capability

In addition, the solder paste inspection machine can detect the following defects:
Whether the solder paste printing is shifted (shift)
Whether the height deviation of solder paste printing (pointing)
Whether solder paste printing is bridged (Bridge)
Whether the solder paste printing is defective or damaged

It’s just that a few devices are machines, and people are the key. SPI is a set of tools that can help improve product quality, thereby increasing production and reducing costs. Will affect the output.

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