What Kind of Solder Paste is Selected for Flip Chip Package?
In recent years, flip-chip technology has been increasingly adopted in consumer electronics and high-performance products. During flip-chip packaging, lead-free solder paste can be used for substrate bumping, modules, and board level connections, etc. What kind of lead-free solder paste should be selected in practical applications?
Considering the process characteristics in combination with your own situation
Due to the properties of lead-free solder paste, there are contradictions that need to be chosen among the characteristics of lead-free solder paste, which makes it impossible to have a perfect product. Solder paste needs to be selected according to process characteristics. For example, when the alloy solder is selected, it is necessary to boost the activity of the solder flux to increase the wettability of the solder paste on the surface of the metals. However, the increase in the activity may produce more flux residues, which can corrode the metal surface after soldering.
The requirement for flip chip reflow soldering should be considered. After flip-chip soldering, module and board-level interconnections are also required. Thus, the requirement to maintain the melting point level of the solder paste must be considered when choosing the solder paste.
Considering the reliability of flip chip interconnection after soldering
Thermal fatigue resistance, drop impact reliability, and electromigration reliability are important factors that affect the reliability of flip-chip interconnect structures.
Studies have shown that solder joints with different alloy compositions behave with different fatigue life for different thermal cycling periods. Under the condition of thermal cycling at 0~100℃ and 120min, the thermal fatigue life of lead-free solder joints with low Ag content [2.1% (mass fraction)] is the longest. However, the short thermal cycling of lead-free solder joints with high Ag content [3.8% (mass fraction)] at 0~100℃ and 30min has the longest thermal fatigue life. It can be seen that selecting appropriate solder paste according to process conditions is necessary to improve reliability.
What kind of lead-free solder paste should be selected for flip-chip packaging is a problem that needs to be comprehensively considered, including both process conditions and solder paste characteristics. The easiest way to choose a suitable lead-free solder paste for the flip chip is to contact us through the contact information below. Our engineers will work with you to select a suitable lead-free solder product.