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How PCBs Are Made

Oct 13

How do circuit boards work, A computer circuit board (PCB) provides the mechanical and electrical connections that enable a computer's various components to communicate with one another and exchange data. The most common PCBs feature a base material called a substrate with conductive pathways, such as copper, that connect the different electronic devices in a computer system. The copper paths also provide power to the computer, and allow for the flow of electrical signals.

Unlike a traditional metal wire that would require a metal coating to carry signals, the copper in a circuit board can carry signals over long distances without losing their strength. However, a PCB requires a dielectric to separate the copper layers from each other. A variety of materials are used as insulating dielectrics, including polytetrafluoroethylene (PTFE or Teflon), FR-2, FR-4, FR-3, GF-5, CEM-1 and CEM-3. A choice of these dielectrics allows for a wide range of electrical properties in a circuit board.

In the early 1900s, German inventor Albert Hanson patented a device that resembled today's PCBs. His flat conductor was part of a multi-layer insulating board and featured through-hole construction, just like today's plated-through holes. Hanson's patent was the first significant advancement in PCB technology and its adaptation into consumer electronics.

PCBs are now an integral part of nearly every digital device and essential to our daily lives. Yet many of us are unaware of how they came to be the important, durable and reliable devices that we depend on for communication and entertainment. The military is to credit for the development of this important technology, and it is a fact that many of the world's most popular computers would not function without a computer circuit board.

The military's invention allowed for a quick assembly process that could mass produce a PCB with minimal labor and cost. The PCB manufacturing process involves laminating a substrate, such as phenolic cotton paper or a glass and epoxy resin, with a layer of copper foil and drawing a wiring pattern on it with acid-resistant ink. The manufacturer then photographs the pattern on a zinc plate and uses it as a template to print more circuit boards.

After the bare PCB is populated with components, it is etched and then soldered. This process creates a permanent connection between the component leads and the copper circuit paths and helps to dissipate heat. After the soldering is completed, a technician may perform in-circuit testing on the device to verify proper operation.

As the use of PCBs in consumer electronics became more widespread, designers began to make the structures more compact and rugged. The rapid evolution of computerized devices since the 1990s has resulted in smaller, more powerful PCBs that have become a staple in the mobile lifestyle of modern society. For example, in just 12 years portable MP3 players have gone from the bulky Archos models to the sleek iPod Nano versions of today.