Choosing a Domestic Solder Paste is not about comparing whose brochure is thicker, but about whether there is false missing printing under the squeegee, cold solder joints and voids after reflow, and ionic residue after cleaning. The 8MQP/5RQ series uses 0307/T4 alloy powder combined with a high-activity rosin system, and the measured solder wetting rate reaches 98% on 0.4mm pitch QFN. However, if the stencil aperture on the production line is too small or the squeegee pressure is lower than 0.45MPa, edge solder shrinkage will occur. In this case, you have to switch to the 8MNTTP/5RNTT series, which adds 00507BN and 00507B2N dual alloy powder. Although the cost is 12% higher, it can stably maintain a solder wetting rate of over 85% on the 0.3mm fine pitch of fingerprint lock motherboards, and the Flux residue is transparent and non-corrosive.

Automotive lamp factories have reported that the void rate of the 8M9P/5RR halogen-free Solder Paste is suppressed below 0.8%, provided that the reflow peak temperature must be strictly controlled at 252±2℃ and the soaking zone is maintained for 150 seconds. Once the heating ramp exceeds 1.8℃/s, the oxide film on the surface of the 0307/T4 powder cannot be reduced by the flux in time, and the void rate will instead soar to 3.5%. If the 8M9P/5RR, which is also nominally halogen-free, is mixed with SC07/T3 powder, the melting point fluctuation will increase to 227℃, leading to local overheating and delamination of the LED package pad.

Factories making lighting LEDs should not blindly pursue halogen-free options. The 8MA series uses 0107/T4 powder with ROL1 grade halogen, which has low and transparent residue, and costs 35% less than ROL0. The void rate during reflow of 2835 packages is 1.2%, which fully meets the standard. On the contrary, if you force the use of 8M9P/5RR, due to insufficient activity, the 2700K color temperature consistency fluctuation will expand from ±150K to ±320K. For water-washable types, pay close attention to the ORH1 standard. The 8MW1P/5RW1 uses SC07/T3 powder, which can pass ion chromatography detection after cleaning in pure water at 60℃ for 3 minutes. However, if you mistakenly use the Sn42Bi58 low-temperature powder of 8MW1AP/5RW1A, gray-white crystals will precipitate on the PCB surface after water washing, which must be removed with a 5% citric acid solution.

Laser welding cannot only rely on the words "laser special". The 5RLJ series T6/T7 grade ultra-fine powder is combined with <500ppm>