Against the backdrop of advanced packaging continuously evolving toward high I/O count, fine-pitch, and large-size BGA, solder joint voiding has become a key bottleneck restricting yield improvement. In BGA applications with 0.4mm and smaller ball pitch, traditional Solder Pastes often suffer from excessive voiding rates due to limited Flux volatilization paths and insufficient alloy melting fluidity, which in turn leads to thermal stress concentration and risks of solder joint cracking. Based on years of experience in rosin-based lead-free solder paste formulation, Jia Jinyuan has developed the halogen-free, REACH-compliant 8M9P/5RR series low-void solder paste. This product adopts a synergistic design of T4-grade 0307 alloy powder and a specially formulated low-volatility active carrier, achieving optimized melt-state viscosity gradient within the standard reflow window of 240℃–255℃, allowing flux decomposition gases to escape efficiently along preset microchannels, thereby stably controlling the void rate within 3% while maintaining high wettability.
This solder paste has passed the full process chain verification of a 12-layer PCB + 1600-ball BGA module at a leading domestic OSAT manufacturer, covering the entire process of SPI solder paste printing, placement, nitrogen-protected reflow soldering, and AOI/X-ray final inspection. Measured data shows that the solder joint bridging rate decreased by 62%, batches with X-ray void exceeding the limit (>15%) dropped to zero, the average rework time per board was reduced by 4.8 minutes, and the overall first-pass yield increased from 92.7% before verification to 99.1%. Customer feedback indicates that it exhibits excellent solder climb consistency and solder joint morphology stability in both 0.3mm pitch FCCSP and 0.4mm pitch BGA scenarios, and can still maintain a wetting coverage rate of over 98% especially on nickel-palladium-gold (ENEPIG) pad surfaces.
The 8M9P/5RR series solder paste continues Jia Jinyuan's LFP-JJY naming system, where 5RR represents the halogen-free high-temperature formulation code, compatible with mainstream lead-free alloy systems such as Sn96.5Ag3Cu0.5 (305) and Sn99Ag0.3Cu0.7 (0307). It is paired with T3/T4 grade high-purity metal powder with sphericity ≥90% and oxygen content <150ppm, ensuring a balance between printing release performance and anti-slump capability, while meeting the stringent requirements of IPC J-STD-005B for residue ionic cleanliness and insulation resistance. Its ROL0 grade halogen residue (measured <50ppm) also reserves an upgrade path for high-reliability scenarios such as automotive millimeter-wave radar modules.
Currently, this low-void solder paste has entered the second round of small-batch introduction at multiple packaging and testing factories, and is being adapted synchronously to the parameters of jet valve and screw valve dispensing equipment, supporting the expansion of process window margin under 0.15mm aperture stencil printing and ±0.05mm placement accuracy. In the future, it will further optimize the solder paste rheological response model for ultra-fine pitch BGA below 0.2mm based on customer feedback, continuously strengthening material adaptability in Chiplet heterogeneous integration packaging.
