The electronic control boards of new energy vehicles are facing the dual challenges of continuously increasing power density and narrowing thermal management boundaries of the whole vehicle. Traditional Solder Paste tends to induce issues such as micro-crack propagation in solder joints, coarsening of interfacial intermetallic compounds, and residue corrosion during wide temperature range cycles from -40℃ to 125℃, leading to a significant rise in functional failure risks. Halogen-free and lead-free high-temperature solder pastes such as JJY LFP-JJY5RQ-0307T4 and LFP-JJY5RR-305, which adopt Sn99Ag0.3Cu0.7 and Sn96.5Ag3Cu0.5 alloy systems, achieve over 90% solder wetting coverage for fine-pitch devices of QFN/DFN types within the 240–260℃ soldering temperature range. Meanwhile, they control the total halogen content within the range of 0–900ppm, meeting automotive-grade ROL0/ROL1 cleanliness requirements and effectively suppressing electrochemical migration caused by ionic residues.

In actual high-low temperature cycle tests, the IGBT drive module equipped with LFP-JJY5RNTT-0307 solder paste retains over 86% of its solder joint shear strength after 1000 cycles of -40℃/125℃. Fracture morphology shows that the IMC layer has uniform thickness with no obvious Kirkendall voids, which is closely related to the inhibitory effect of Bi and Ni elements in the 00507BN microalloy composition on the growth of Cu6Sn5 phases. The water-washable LFP-JJY5RW1-0307 solder paste, while balancing post-soldering cleanability, ensures slump stability under 255℃ peak reflow and thermal conductivity consistency with a void rate below 3.2% through the compound powder ratio of SC07 and 0307.

For the new laser selective soldering process, the LFP-JJY5RLJ-305 series adopts T5–T7 grade ultra-fine spherical powder and low-volatility rosin carrier, achieving precise splash-free and solder-ball-free fusion welding under a laser power density of 15–25W/cm2. Combined with its <500ppm