Printed Circuit Boards Essay Example | Topics and Well Written Essays - 2000 words

Printed Circuit Boards - Essay Example Components can be connected on the PCB through conductive paths or etched copper wiring on a non-conductive substrate such as plastic. A PCB that has been assembled with such electronic components through appropriate connections is known as a Printed Circuit Assembly (PCA) (Khandpur, 2007). PCBs are relatively cheap and are known for their durability and reliability. While finding the material for the substrate and the conductive paths, much effort needs to be spent on defining a proper layout as well as the nature of the connections among various circuit elements. For example, a proper layout is necessary to accommodate all the required components and ensure proper connections among them to produce the desired output. Jawitz (2008) says that care needs to be taken when determining the type of connections (like point-to-point or wire wrap) besides ensuring that no unwanted contact is established due to crossing wires or faulty connections. Post this layout phase, production of PCAs i n high volumes is relatively easier and can be accomplished by an automated assembly line. The design and construction of PCBs is governed by a number of standards that are set and revised regularly by the Association Connecting Electronics Industries (IPC). PCBs, with the etched copper pathways, are insulated from any contact with dust or moisture (thereby avoiding undesired electrical connections and short circuits) using green-colored solder. Some PCBs are also coated with blue and red colored solder. In fact, Bosshart, 2003 says that the choice of the solder, technically a dielectric known for very high resistance and lack of electrical conduction, can vary depending on the purpose of the circuit being developed. Some of the popular and widely used dielectrics include FR-1, CEM and Teflon. The underlying substrate that makes up the flat-board can be made from a combination of cotton paper, polyester, epoxy and glass. Dimensional stability combined with lack of expansion on expos ure to heat qualifies these substances as highly suitable for PCB production. The average thickness of a PCB can range anywhere from 1 to 2mm (Montrose, 2009). Components can either be assembled on 1 side of the board or configured on both sides depending on requirements and space considerations. Types of PCBs PCBs come in many types based on a number of factors ranging from the number of sides utilized to the kind etching technology adopted for providing the interconnects. PCBs can also consist of multiple layers of the substrate and the interconnecting copper pathways and can thus be highly complex in construction. The following points describe some of the types into which most PCBs can be categorized. Single-sided PCBs These are the most basic type of PCBs and can be constructed even from a regular plastic board. A single sided PCB consists of electronic components soldered on one side while the pathways and interconnections are provided on the other side of the board. The term s ingle-side arises from this segregation among components and pathways and their restricted location to a single side of the PCB (Robertson, 2004). Single-sided PCBs have a number of deficiencies in terms of routing and circuit connections whereby no two wires can cross each other. Thus, single-sided PCBs may consumer more wire or copper for the necessary interconnects and are thus relatively resource intensive than other PDB types. As such, they are preferred for the construction of primitive circuits and cannot be used for developing advanced circuitry. Double-sided PCBs As the name suggests, these PCBs have the pathways etched on both sides of the board.