Capacitance is one of the common components of SMD processing, basically every PCBA board is covered with various types of capacitors, responsible for different functions.
There are many types of capacitors, in the SMT placement process, basically most of them are chip capacitors.
SMD capacitors in the SMT placement process is a common bad is empty solder (also called false solder).
Today we will talk to you about the chip processing capacitors appear empty solder causes and countermeasures.
PCB pads are getting smaller and smaller, so the printing accuracy requirements are getting higher and higher, solder paste printing offset (in layman's terms is not printed on the pad or offset a lot, only printed to a part of the pad), which will lead to reflow soldering, part of the solder paste melting, and the other part of the paste melting time is longer and not completely melted so that the component crawl tin fixed, resulting in the appearance of empty solder, false solder bad quality The
For this reason lead to the countermeasure is need to improve the quality of solder paste printing, Z is good in the solder paste printing machine behind an additional SPI (specifically for detecting the quality of solder paste printing).
The mount machine is concerned about the speed and precision of the mount, the precision is refers to the component material number mount to the pcb pad bit number above, some mount machine mount precision is poor, there are some mount offset then will lead to appear empty solder.
Countermeasure: reduce the placement speed or replace the placement precision higher placement machine.
Reflow soldering is four temperature zones, in the soldering zone is the temperature Z high, this temperature zone will pad on the solder paste are melted so that the components climb tin, some products some electronic components are small, and some are big, will lead to uneven heating, melt tin time is not the same, thus leading to empty soldering, another is due to the furnace temperature curve does not meet the requirements and lead to control.
Countermeasures: filtering time and furnace temperature curve settings, should be used to test the furnace temperature tester, in the prototype stage to do more than the first test OK board.
SMD processing capacitor empty soldering needs to be paid attention to, so as not to affect the capacity and customer complaints.
