Solder Paste spattering during Reflow Soldering is rarely caused by a single factor; it is usually the combined result of uneven stencil tension, excessive squeegee pressure, a sudden local viscosity drop when the paste is sheared at the stencil aperture edge, and violent Flux vaporization caused by rapid heating in the reflow zone. At an automotive module production line in Dongguan, for example, continuous spattering residue around 0201 components occurred at a peak temperature of 245°C when using ROL1-grade solder paste with a relatively high halogen content. After switching to our JJY LFP-JJY5RR-0307, the spatter rate dropped from 8.3 defects per thousand boards to 0.4. This model uses 0307 alloy powder with a T4 particle size distribution and a halogen-free rosin system, and exhibits a more gradual viscosity decay curve within the 235–255°C soldering window.

The core of anti-spattering solder paste is not “no spattering” but “controlled spattering.” This means the paste must maintain a sufficient yield value during printing to resist squeegee shear disturbance, while rapidly forming a dense metal skeleton in the early reflow stage to suppress flux vapor penetration. LFP-JJY5RNTT-0307 introduces trace Bi/Ni composite modification and further optimizes the uniformity of particle surfactant coating based on 00507BN alloy powder. Measured under a 300-mesh stencil and 1.5mm squeegee stroke, its spatter particle count is 42% lower than that of conventional 305-series solder paste. Meanwhile, its solder wetting coverage for QFN devices at 0.4mm pitch remains stably above 92%, making it especially suitable for high-density assembly scenarios such as tablets and fingerprint locks.

The key to improving the reliability of Domestic Solder Paste lies in the batch stability of alloy powder and its compatibility with the rosin vehicle. After comparing samples from 12 suppliers, only our JJY 0307T4 powder controls D50 fluctuation within ±0.3μm. Combined with its ROL0-grade rosin system, the void rate can be reduced to 3.7% in a nitrogen-protected reflow oven. Under the same process conditions, a Korean brand reached a void rate of 6.9% with the same stencil parameters. This shows that Reflow Solder Paste selection cannot rely solely on melting point or nominal activity; it must be verified in a closed loop against the production line’s actual stencil thickness, squeegee hardness, and printing speed.

For production lines already experiencing spattering, it is recommended to first check whether stencil cleaning frequency is lower than once per 500 boards, whether solder paste warm-up time is less than 4 hours, and whether the cooling-zone airflow velocity in the reflow oven exceeds 1.8m/s. Uneven cooling can disrupt the solidification front of solder joints and worsen secondary adhesion of spatter. In this case, using LFP-JJY5RW1-0307 water-washable solder paste cannot eliminate spattering completely, but it can greatly reduce subsequent cleaning difficulty. Its SC07/0307 mixed powder structure achieves a residue removal rate of 99.1% at a spray pressure of 0.25MPa, an improvement of 11.6 percentage points over a pure T4 powder solution.

In laser welding scenarios, attention should be paid to the spatter amplification effect of low-temperature solder paste during high-speed dispensing. For example, the Sn42Bi58 system is highly prone to micro-droplet drift caused by excessive shear thinning when the jet valve frequency exceeds 120Hz. LFP-JJY5RLJB-4258 adjusts the rosin softening point to 68°C and adds nano-silica thickener, raising the spatter threshold to 142Hz. It has already achieved 270,000 consecutive dispensing points without rework at a MiniLED driver board production line in Suzhou. This shows that anti-spattering solder paste must be matched to the specific dispensing method and equipment cycle time; discussing performance without process parameters is purely theoretical.