1. Abnormal Metal Luster

The disappearance of the grayish-white metal luster, with the solder paste surface appearing dark yellow or grayish-black, indicates oxidation deterioration of the solder powder. Experiments show that when the oxidation degree reaches 0.3%, solder joint strength drops by 40%. This poses a direct threat to precision signal transmission in medical equipment.

2. Foreign Particle Contamination

Imagine this: On a highway only 0.3mm wide (QFP component pad spacing), a 0.1mm stone (steel debris impurity) suddenly appears. What kind of traffic disaster would this cause? This is a true reflection of metal contaminants on a circuit board—steel debris with a diameter 1.5 times that of a hair is enough to cause "multi-car rear-end" bridging short circuits in a 5mm² pad area (about half the size of a grain of rice), just like throwing a soda can on a highway causing a multi-vehicle collision.

3. Layering Phenomenon

Phase separation of solder paste is like the "oil-water separation" of milk tea after standing for a long time—qualified solder paste should present a uniform and delicate cream-like state, while failed samples will separate out a transparent or pale yellow flux layer, and a clear difference in texture between the upper and lower layers can be felt when picked up with a spatula.

4. Solder Powder Agglomeration Defects

Opening the refrigerator on a cold winter morning, the surface of vegetables in the refrigerator compartment will instantly frost—when insufficiently rewarmed solder paste is opened, moisture in the air condenses on the surface of the solder powder like magic into tiny ice crystals; this is the "ice crystal effect."

When these ice crystals melt, the solder powder clumps together like damp sugar, forming particles with a diameter exceeding 80μm (twice the size of fine salt grains), completely deviating from the Type 4 standard.

5. Abnormal Precipitates

Surface oil film or crystals imply an imbalance in the flux formula, which may trigger an "electrochemical migration" disaster on mobile phone motherboards. Abnormal precipitates in solder paste are like the paste "sweating"—qualified solder paste should remain a dry, fine powder, while failed samples will have a transparent oil film or white crystals floating on the surface, a dangerous signal that flux components are "running away from home."

Earlysun Technology: Quality is the First Lifeline

Today, as electronic component dimensions enter the micrometer level, solder paste appearance inspection has gone beyond simple "looking"; it is a precision system integrating materials science, optical technology, and artificial intelligence. Factories still using magnifying glasses for manual inspection are unknowingly on the path to obsolescence.

Earlysun Technology strictly controls every link in the solder paste production process. From raw material screening to finished product packaging, every bottle of solder paste undergoes rigorous weighing and visual inspection to ensure that the net weight meets standards and the appearance is flawless.

In the world of SMT, the most expensive cost is always "I thought it was okay." Choosing a brand like Earlysun Technology with excellent quality and strict quality control undoubtedly adds a solid line of defense to SMT production, giving your products a greater advantage in market competition and fearlessness against quality challenges.