Reliability generally refers to the probability that a product will perform a specified task under specified conditions within a specified time. It is related to the corresponding load, usage environment, and application cycle. It is usually evaluated by using a temperature cycling method.
The reliability of lead-free interconnects is a very complex issue, and simply depends on the “acceleration factor” of the test.
In most applications, the product is in the environment of 0-100 ° C, the load is relatively low, lead-free is more reliable than lead ; but for automotive electronics, military products, the operating temperature is often below 50–150 ° C. The solder joints are subjected to a large load, and the lead solder joints are often more reliable than the lead-free solder joints.
The lead-free craft and ROHS are two concepts. The lead-free craft refers to the usage of lead-free solder. It is a crafts technology that realizes interconnecting PCB and SMD that meet ROHS requirements.
The lead-free craft has the following characteristics compared to the lead craft:
1.Increased solder melting point
3.The fluidity is deteriorated, and the fluidity of the lead-free solder is deteriorated due to the relative shortage of the superheating temperature, and the melting of the copper at a high temperature causes the fluidity to be worse, and in general, the weldability is deteriorated.
1.Snpb Hot Air Leveling craft. The Snpb Hot Air Leveling craft is a traditional PCB pad coating method. The specific craft process is immersed in the molten Snpb alloy after the PCB circuit is etched, and then slowly lifted and coated with a Snpb alloy layer under the action of hot air, which is ...
The width of the printed conductor depends on the current carrying capacity of the conductor and the allowable temperature rise. The thickness of the copper foil plated copper foil is generally 0.02 to 0.05 mm. The different widths printed conductors have different cross-sectional areas too. The ...
After the position and shape of the components on the PCB board are determined, the wiring can be performed according to the position of the components. The following are the basic requirements for the circuit board: The low frequency wires are placed close to the edge of the printed circuit boar...