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Printed Circuit Board Introduction & PCB Types
What is PCB?
Printed circuit boards (PCBs) are the boards that are used as the base in most electronics – both as a physical support piece and as the wiring area for the surface-mounted and socketed components. PCBs are most commonly made out of fiberglass, composite epoxy, or another composite material.
Most PCBs for simple electronics are simple and composed of only a single layer. More sophisticated hardware such as computer graphics cards or motherboards can have multiple layers, sometimes up to twelve.
Although Metal Core PCBs are most often associated with computers, they can be found in many other electronic devices, such as TVs, Radios, Digital cameras and Cell phones. In addition to their use in consumer electronics and computers, different types of PCBs are used in a variety of other fields, including:
1. Medical devices. Electronics products are now denser and consume less power than previous generations, making it possible to test new and exciting medical technology. Most medical devices use a high-density PCB, which is used to create the smallest and densest design possible. This helps to alleviate some of the unique constraints involved with developing devices for the medical field due to the necessity of small size and light weight. PCBs have found their way into everything from small devices, such as pacemakers, to much larger devices like X-ray equipment or CAT scan machines.
2. Industrial machinery. PCBs are commonly used in high-powered industrial machinery. In places where current one-ounce copper PCBs do not fit the requirements, thick copper PCB can be utilized instead. Examples of situations where thicker copper PCBs would be beneficial include motor controllers, high-current battery chargers and industrial load testers.
3. Lighting. As LED-based lighting solutions catch on in popularity because of their low power consumption and high levels of efficiency, so too does aluminum-backed PCB which is used to make them. These PCBs serve as heat sinks and allow for higher levels of heat transfer than a standard PCB. These same aluminum-backed HDI Circuits form the basis for both high-lumen LED applications and basic lighting solutions.
4. Automotive and aerospace industries. Both the automotive and aerospace industries make use of flexible PCB, which is designed to withstand the high-vibration environments that are common in both fields. Depending on specifications and design, they can also be very lightweight, which is a necessity when manufacturing parts for transportation industries. They are also able to conform to the tight spaces that might be present in these applications, such as inside instrument panels or behind the instrument gauge on a dashboard.
There are several different types of circuit boards, each with its own particular manufacturing specifications, material types, and usages:
A single-layer or single-sided PCB is one that is made out of a single layer of base material or substrate. One side of the base material is coated with a thin layer of metal. Copper is the most common coating due to how well it functions as an electrical conductor. Once the copper base plating is applied, a protective solder mask is usually applied, followed by the last silk-screen to mark out all of the elements on the board.
Multilayer PCBs consist of a series of three or more double-layered PCBs. These boards are then secured together with a specialized glue and sandwiched between pieces of insulation to ensure that excess heat doesn't melt any of the components. Multi-layer PCBs come in a variety of sizes, going as small as four layers or as large as ten or twelve. The largest multi-layer PCB ever built was 50 layers thick.
With many layers of printed circuit boards, designers can make very thick, complex designs which are suitable for a broad range of complicated electrical tasks. Applications where multi-layer PCBs would be beneficial include File servers, Data storage, GPS technology, Satellite systems, Weather analysis and Medical equipment.
Rigid PCBs are made out of a solid substrate material that prevents the board from twisting. Possibly the most common example of a rigid PCB is a computer motherboard. The motherboard is a multilayer PCB designed to allocate electricity from the power supply while simultaneously allowing communication between all of the many parts of the computer, such as CPU, GPU and RAM.
Rigid PCBs make up perhaps the largest number of PCBs manufactured. These PCBs are used anywhere that there is a need for the PCB itself to be set up in one shape and remain that way for the remainder of the device's lifespan. Rigid PCBs can be anything from a simple single-layer PCB all the way up to an eight or ten-layer multi-layer PCB.
All Rigid PCBs have single-layer, double-layer or multilayer constructions, so they all share the same applications.
Unlike rigid PCBs, which use unmoving materials such as fiberglass, Flexible PCB is made of materials that can flex and move, such as plastic. Like rigid PCBs, flexible PCBs come in single, double or multilayer formats. As they need to be printed on a flexible material, flexible pcb cost more for fabrication.