We have tracked the actual performance of three of our JJY no-clean Solder Pastes on 0.4mm pitch QFN devices at an ODM factory in Shenzhen for three consecutive months. Among them, the 8MQP/5RQ series, with total halogen controlled within 1500ppm and using T4-grade 0307 alloy powder, achieved a solder climbing height of 0.12mm above the pad edge after reflow, with solder climbing coverage close to 100%. However, its ROL1 grade caused a slight white film residue at the bottom of some high-density BGAs, requiring nitrogen protection to reduce the void rate to below 8.2%. The 8MNTTP/5RNTT series further reduced halogen to the 100~200ppm ROL0 level, paired with 00507BN ultra-fine alloy powder, achieving transparent, residue-free performance on tablet motherboards and stable QFN solder climbing at 85%~90%. However, it is more sensitive to stencil aperture accuracy; when the stencil thickness deviation exceeds ±0.5μm, the printing release rate drops by 12%. As a zero-halogen REACH-compliant model, 8M9P/5RR controlled the void rate at 3.7% on automotive LED lighting boards and maintained bright, corrosion-free solder joints. However, its T3-grade 305 alloy powder exhibited slight solder bead aggregation at a peak reflow temperature of 260°C, requiring the reflow soak zone to be extended to 90 seconds to suppress this issue, which directly reduced the line UPH from 1800 to 1620.

We found that batch stability differences among Domestic Solder Pastes are mainly reflected in two variables: the Flux volatilization curve and the thickness of the alloy powder oxide layer. For example, for 0307 alloy of the same T4 powder grade, the batch-to-batch fluctuation range of the solvent initial boiling point for 8MQP/5RQ reached 142~149°C, while that for 8MNTTP/5RNTT was stable at 145±1.2°C. This difference makes the former more prone to stencil clogging in low-humidity winter environments, while the latter exhibits stronger anti-slump performance in high-temperature summer workshops. In addition, the surface oxide content of the 305 powder used in 8M9P/5RR was measured by XPS to be 0.87wt%, 0.15 percentage points lower than the industry average. This explains why it can maintain a low void rate even in a simple reflow oven with only 85% nitrogen concentration, but it also brings the problem of fast solder viscosity attenuation: the viscosity drops by 18% within 4 hours after opening the can, requiring strict replacement with a new can every shift.

During line verification, we paid special attention to the compatibility between no-clean solder pastes and domestic stencils. We found that 8MQP/5RQ achieved a printing yield of 99.3% on a 300-mesh laser-cut stencil, but after switching to a domestic electroformed stencil, the poor release rate rose to 2.1% due to hole wall roughness Ra > 0.4μm. In contrast, 8MNTTP/5RNTT, with slightly lower flux activity, showed better adaptability to electroformed stencils, with a poor release rate of only 0.7%. However, it is more sensitive to squeegee pressure: when the pressure increased from 5.2kg to 5.8kg, the bridging rate on 0.3mm pitch pads jumped from 0.03% to 0.21%. 8M9P/5RR performed stably on both types of stencils, but requires the squeegee angle to be locked at 60°±1°; an angle deviation exceeding 1.5° will cause solder tailing, which is easily overlooked in multi-variable mixed-line production.