How to solve the empty problem in welding!
Release time:
2022-10-26
【Summary Description】 At present, consumer electronics companies in other countries, except Japan, seem to have accepted the tin-silver-copper alloy series, with the proportion of silver in the alloy being 3,0% to 4,7%; copper is 0,5% to 3,0%. The melting point of the alloy of different components is not much different, basically changing between 2l7 ~ 22l ℃, the liquid phase temperature of the tin-lead alloy is 183 ℃, the difference between the two is 34 ℃. Therefore, it is very important to closely monitor this stage at the beginning, focusing on the key variables in the reflow process, such as peak temperature, time above liquid phase temperature, immersion time, diffuse temperature, and ramp rate due to the choice of flux and solder paste, to ensure that the reflow process maintains a Cpk of 1,33 or higher. In addition, void is a common defect in reflow soldering of interconnect solder joints, especially in BGA/CSP and other components. The second generation of general-purpose solder paste formed by the progress of materials in the past two years, in addition to having a wider process window, easier application, and better appearance, the most important thing is to solve the void problem. SMT, MCM process problems. Including improper solder storage temperature, insufficient solder pad, and improper setting of reflow soldering temperature curve. In the case of lead-free soldering, the optimization of the temperature profile in the reflow process is critical to ensure a highly reliable solder connection while maintaining the lowest possible peak temperature. In lead-free soldering, voids are still a problem of concern, because in the molten state, the surface tension of Sn/Ag/Cu alloy is greater than that of Sn-Pb alloy, and the increase of surface tension will inevitably make it more difficult for gas to overflow during the cooling stage, so that the proportion of voids increases. This was confirmed during the development of lead-free solder paste, which showed that the number of voids in solder joints using lead-free solder paste was greater than that of solder joints using tin-lead solder paste. The large voids and some small spherical voids are caused by the volatilization of the flux. The ratio of the flux in the solder paste is the most direct factor affecting the solder joint voids, so there is still much room for improvement in the lead-free solder paste. As a new generation of lead-free solder paste products, Multicore(96SC LF320 AGS88) has increased the activity of flux at high temperature and achieved a great leap in technology, reducing the void level of lead-free solder joints to 7,5%.
At present, consumer electronics companies in other countries, except Japan, seem to have accepted the tin-silver-copper alloy series, with the proportion of silver in the alloy being 3,0% to 4,7%; copper is 0,5% to 3,0%. The melting point of the alloy of different components is not much different, basically changing between 2l7 ~ 22l ℃, the liquid phase temperature of the tin-lead alloy is 183 ℃, the difference between the two is 34 ℃.
Therefore, it is very important to closely monitor this stage at the beginning, focusing on the key variables in the reflow process, such as peak temperature, time above liquid phase temperature, immersion time, diffuse temperature, and ramp rate due to the choice of flux and solder paste, to ensure that the reflow process maintains a Cpk of 1,33 or higher. In addition, void is a common defect in reflow soldering of interconnect solder joints, especially in BGA/CSP and other components.
The second generation of general-purpose solder paste formed by the progress of materials in the past two years, in addition to having a wider process window, easier application, and better appearance, the most important thing is to solve the void problem.
SMT, MCM process problems. Including improper solder storage temperature, insufficient solder pad, and improper setting of reflow soldering temperature curve. In the case of lead-free soldering, the optimization of the temperature profile in the reflow process is critical to ensure a highly reliable solder connection while maintaining the lowest possible peak temperature.
In lead-free soldering, voids are still a problem of concern, because in the molten state, the surface tension of Sn/Ag/Cu alloy is greater than that of Sn-Pb alloy, and the increase of surface tension will inevitably make it more difficult for gas to overflow during the cooling stage, so that the proportion of voids increases. This was confirmed during the development of lead-free solder paste, which showed that the number of voids in solder joints using lead-free solder paste was greater than that of solder joints using tin-lead solder paste. The large voids and some small spherical voids are caused by the volatilization of the flux. The ratio of the flux in the solder paste is the most direct factor affecting the solder joint voids, so there is still much room for improvement in the lead-free solder paste. As a new generation of lead-free solder paste products, Multicore(96SC LF320 AGS88) has increased the activity of flux at high temperature and achieved a great leap in technology, reducing the void level of lead-free solder joints to 7,5%.
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