In PCB (Printed Circuit Board), Sn and Pd refer to two metal elements.
Sn is tin, which is commonly used in electronic connectors, soldering materials, etc. In PCB manufacturing, tin is used to solder electronic components to circuit boards.
Pd is palladium, which is also a metallic element. In PCB manufacturing, palladium is often used as a resist or plating layer to protect circuit boards from corrosion or enhance their conductive properties.
Therefore, Sn and Pd each have specific uses and importance in PCB manufacturing.