All JJY RoHS Solder products have passed SGS testing, with lead content <100ppm, cadmium <50ppm, and mercury <500ppm. All Solder Paste batches are accompanied by original third-party reports compliant with IEC 62321 standards. Before procurement and warehousing, the COA number must be fully verified against the physical batch number; otherwise, the goods will be rejected.

Solder paste selection must match stencil aperture and reflow oven capabilities

For densely populated boards with 0402 components, J-880H solder paste is preferred. With 90.5% metal content, 720Pa·s viscosity (25℃), and a thixotropic index of 2.3, paired with a 0.12mm thick laser-etched stencil and 25μm aperture, it can achieve a release rate >99.2%. If the line's reflow oven peak temperature can only reach 238℃, J-850L low-melting-point solder paste must be used instead; otherwise, a large number of BGA solder joints will exhibit both cold soldering and bridging.

Flux residue must be controlled during Solder Wire welding

JJY lead-free solder wire uses rosin-based no-clean flux, with 2.8% solid content and <0.05% halogen content. At a 0.5mm wire diameter, the drawing length reaches 1.8m without breakage. However, if the soldering tip temperature exceeds 380℃ and the contact time exceeds 3 seconds, flux carbides will form a brownish film residue on the PCB surface. In this case, 99.9% isopropanol must be used with an ultrasonic cleaning machine for treatment; otherwise, the AOI false alarm rate will increase by 47%.

Wave soldering with Solder Bars requires simultaneous monitoring of copper corrosion and solder joint brightness

When J-TL63 solder bars are used for nozzle-type wave soldering, the copper content in the solder bath must be tested every 8 hours of operation. When Cu >0.25%, the electrolytic purification device must be activated immediately; otherwise, OSP board solder joints will appear dull, whitened, and have a 12% reduction in thrust. At the same time, check whether the surface tension of the molten solder bar is maintained at around 0.58N/m. A deviation exceeding ±0.03N/m indicates a shift in the Sn/Ag/Cu ratio.

Solder of different forms must not be mixed in the same temperature zone

A customer once mixed JJY solder paste with non-same-source solder wire for rework on the same motherboard. As a result, a large number of Cu6Sn5 and Ni3Sn4 double-layer IMC structures appeared at the bottom of the BGA. X-ray tomography showed that the interface thickness fluctuation reached 3.2μm, leading to a sharp increase in solder joint cracking rate to 8.7% after high-temperature aging. The root cause was that the silver content in the solder paste was 0.3% while the solder wire contained 0.5% silver, resulting in local component imbalance after mutual dissolution in the molten state.

Storage and thawing must strictly implement dual temperature and humidity control

Unopened solder paste must be stored in an environment of 25±2℃ and RH <40%. If exposed to room temperature of 22℃ for more than 4 hours after opening, the attenuation of its active components will cause the number of solder balls after reflow to increase by more than 3 times. The thawing process must adopt stepwise heating: first let it stand in a 15℃ constant temperature box for 2 hours before moving it to the work area. Skipping this step will cause internal stratification of the solder paste and splashing at the squeegee edge.