On January 1, 2026, three capacitor-grade PCB manufacturers in Suzhou Industrial Park simultaneously launched a new version of the SMT Solder process parameter package. This solution was jointly verified by Shengyi Technology, Yuntian Semiconductor, and the Institute of Microelectronics of the Chinese Academy of Sciences. It focuses on in-situ passivation control of nano-scale tin oxide in the tin-silver-copper alloy system, widening the low-temperature activation window of rosin-based Flux, and embedding a dynamic compensation algorithm for post-Printing Solder Paste collapse. As a result, the bridging defect rate of SMT solder in 0.25mm pitch QFN device soldering is reduced by 37% compared to the 2024 industry average, and it is compatible with the data feedback closed loop of mainstream domestic SPI and AOI equipment.

According to mass production data statistics from a Shenzhen EMS foundry in the fourth quarter of 2025, the Reflow Soldering first-pass yield of batches using the optimized SMT solder remains stable at 99.23%, an increase of 1.6 percentage points compared to the previously used conventional no-clean Solder Paste. Moreover, in the temperature cycle test from -40℃ to 125℃, the attenuation range of solder joint shear strength is controlled within 4.1%, meeting the technical requirement of the revised automotive-grade AEC-Q200 standard that the thickness fluctuation rate of solder joint intermetallic compounds (IMC) ≤8%. This indicates that this SMT solder has substantially broken through the process barrier for extending from consumer electronics to automotive electronics.

A Shanghai-based multinational semiconductor packaging and testing enterprise completed production line switching in mid-December 2025, replacing its original imported high-activity SMT solder with a locally formulated version. Its core improvement lies in reducing the content of diethanolamine derivatives in the flux by 19%, while introducing phosphate ester corrosion inhibitor components. Under the premise of maintaining the same wetting time, the post-soldering surface ion residue is reduced from the original 125μg/cm² to 78μg/cm², effectively avoiding the abnormal contact impedance problem of ICT test probes in high-humidity environments. This adjustment does not add extra cleaning processes nor extend the peak duration of the standard reflow profile.

It is worth noting that this round of SMT solder process optimization is not a single material iteration. Instead, it relies on the real-time thermal field modeling capabilities accumulated by the supporting packaging lines of domestic 12-inch wafer fabs, and reversely embeds solder melting kinetic parameters into the stencil aperture design rule database. This controls the solder paste volume deviation corresponding to 01005 component pads within ±3.2%. This collaborative mechanism has been standardized and reused on a total of seven SMT production lines in Wuxi and Dongguan, reducing the average first-article debugging time by 27 minutes. This reflects that SMT solder is shifting from passive adaptation to a system-level process element deeply coupled with equipment, processes, and inspection links.

Currently, four domestic Solder Paste Manufacturers have submitted revised draft proposals for SJ/T 11825-2025 "General Specification for Solders for Surface Mounting" based on this technical path, focusing on supplementing rheological performance grading indicators and flux residue evaluation methods for micro-pitch applications below 0.2mm. Relevant discussions have been included in the 2026 annual work plan of the National Technical Committee for Physical and Chemical Materials for Electronic Equipment Standardization, marking that the technological evolution of SMT solder is accelerating from terminal application-driven to standard system-driven.