SURFACE TREATMENT PROCESS

Anti-Oxidation (OSP):

Provides oxidation resistance, thermal shock resistance, and moisture protection to prevent further rusting (oxidation or sulfidation) of copper surfaces under normal conditions. However, during subsequent soldering at high temperatures, this protective film must be easily and quickly removed by flux to allow clean copper surfaces to immediately bond with molten solder and form strong solder joints.

Rosin:

Offers excellent low-temperature viscosity, oxidation resistance, and moisture protection to prevent further oxidation of copper surfaces under normal conditions. However, it is unstable under light, heat, and oxygen, exhibiting poor aging resistance and weather resistance. During subsequent high-temperature soldering, it acts as a flux. Compared to OSP, rosin is more cost-effective and suitable for low-end single-sided PCBs.

Immersion Gold Process:

The purpose of the immersion gold process is to deposit a nickel-gold plating layer with stable color, good brightness, even coating, and excellent solderability on the printed circuit surface. It generally consists of four stages:pretreatment (degreasing, micro-etching, activation, post-dip),nickel immersion, gold immersion,and post-treatment (waste gold rinsing, Dl water rinsing, drying).

Leaded HASL:

The eutectic temperature of leaded solder is lower than lead-free, with the exact difference depending on the lead-free alloy composition. For example.SnAgCu (SAC) has a eutectic temperature of 217 C, and the soldering temperature is typically 30-50 C higher than the eutectic point, depending on adjustments. Leaded eutectic temperature is 183 C. Leaded solder offers better mechanical strength and brightness compared to lead-free. However, it is not suitable for customers requiring RoHS compliance.

Lead-free HASL:

Lead enhances the activity of solder during welding, making leaded solder easier to use and cheaper. However, lead is toxic and harmful with long-term exposure. Lead-free solder has a higher melting point than leaded solder,resulting in stronger solder joints.

Immersion Nickel Process:

The purpose of the immersion nickel process is to deposit a nickel nickel process is to deposit a nickel brightness, even coating, and excellent solderability on the printed circuit surface. It omits the gold immersion step, making it more cost-effective for customers sensitive to expenses but requiring wire bonding or surface protection on pads.