Soldering guidelines for module PCB mounting

What is PCB?
1. Acronym for Printed Circuit Board. A flat board made from an insulating material whose front contains slots for integrated circuit chips and connections for a variety of electronic components, and whose back is printed with electrically conductive pathways between the components. A PCB can have several layers of circuitry. 2. Poly-Chlorinated Biphenyl, a synthetic, organic chemical once widely used in electrical equipment, specialized hydraulic systems, heat transfer systems, and other industrial products. Highly toxic and a potent carcinogen. Handling is generally regulated in all developed countries, including the United States and the EU.