How to improve the welding quality of PCB

- Jul 26, 2018-

In addition, the electronic component fastener (Mounter), which supports high density packaging, has also carried out the high-precision revolution. At present, the packaging precision of the electronic component fastener has achieved the required level of + / -50mm mass production.
Although the electronic component fixator has reached the high precision packaging level, it is difficult for the production line to fully maintain this capability. Therefore, this paper discusses the management method of using special tin paste inspection equipment to make the printing amount of tin paste quantitative, and the simple verification method of electronic component stabilizer.
Analysis of soldering furnace solder paste printing
Figure 1 is the analysis diagram of the quality factors of the Reflow manufacturing process of printed circuit substrate (PCB). As shown in the figure, many welding and encapsulation related defects will occur in the manufacturing process of the Reflow furnace.FIG. 2 and FIG. 3 respectively show the specific contents of welding and poor packaging.
It can be seen from figure 2 that the main causes of bad welding are insufficient welding and unwelded soldering, and the defects caused by bad solder paste printing are the most, accounting for about 80% of the bad welding elements as a whole.
Regarding the bad printing of tin paste, as shown in figure 3, it mainly depends on three important factors. If the printing of tin paste is stable at PPM level, it is quite difficult to achieve high welding quality stability if the printing results are observed quantitatively.

Figure 4 is a summary of the bad content of packaging elements. It can be seen from the figure that the ratio of component upwarping is the highest.
X-Y or even in cases with large deviation, the printing tin paste did not contact the electrode of the welding assembly when the assembly was laid, and the single electrode was affected by zero-cross time of welding.
Small electronic components of chips with low self-weight will float and become warped. Even if the two electrodes touch the tin paste, they may be offset.