Product type: Multi layer board
texture of material: FR4 S1000-2
Application field: Medical equipment
Layer number/plate thickness: 4L/1.6mm
Surface treatment: immersion gold
Line width/spacing: 6/6mil
Minimum aperture: 0.4mm
Technical features: high reliability
Sinking gold: also known as sinking nickel gold or chemical nickel gold. It refers to depositing a certain thickness of nickel on the surface conductor of PCB by chemical method, and then replacing a certain thickness of gold layer (0.025-0.075um) on the nickel layer.
Advantages: Good surface flatness of the solder pad, providing protection for both the surface and sides of the solder pad. In addition to being weldable, it can also be used for various lap welding or wire bonding;
Disadvantages: The process is complex, the cost is high, and there are drawbacks such as missed plating and infiltration plating under specific conditions. The nickel layer contains 6-9% phosphorus. The most troublesome thing is that due to the density of gold plating, a black disk effect (passivation of the nickel layer) may occur, making it difficult to attach or causing parts to fall off. The mechanism of black disk formation is very complex, occurring at the interface between Ni and gold, directly manifested as excessive oxidation of Ni. If the thickness of the deposited gold exceeds 5U, it will make the solder joints brittle and affect reliability.
