Circuit Boards

The printed circuit board, also known by the name printed wiring cards or printed wiring boards is a known and important element in electricals. Prior to the invention of the printed circuit board, the process of creating a circuit is very tedious and involved an extensive manual process of wiring from one point to another. This presents itself with a major issue of failures at the wire junctions. Also, whenever the insulation starts to wear out, there would be short circuits.

Wire wrapping, in which a thin gauge wire is physically wrapped around a post at each connecting point to provide a gas-tight connection that is highly robust and easily adjustable, represents a significant advancement.

As silicon and integrated circuits replaced vacuum tubes and relays in electronics, the size and price of electronic components started to come down. Then the demand for electronics by everyday consumers started to increase and electrical companies started to come up with better solutions to produce electronic goods that are affordable and portable. Hence, the PCB was created and it proved to be one of the greatest solutions in electrical.

The PCB is a circuit board with lines and pads that join different places. The various connectors and components are electrically connected. Between physical devices, communications and power can be routed via a PCB.

The metal used to attach the electronic components to the PCB's surface electrically is called solder. Since solder is made of metal, it is also a powerful mechanical adhesive.

Typically, fiberglass serves as the substrate or base material. Historically, "FR4" has been used to designate this fiberglass the most frequently. The rigidity and thickness of the PCB are a result of this solid core. Additionally, flexible PCBs constructed from flexible high-temperature plastic exist and this plastic is usually Kapton or other material similar to it. PCBs are of varying thicknesses the common one being PCBs for Spark Fun with a thickness of 1.6mm. Arduino Pro Micro boards and Lily Pad boards use boards that are 0.8mm thick.

Printed Circuit Boards can also be made of cheaper materials like phenolics and epoxies. These types of boards produce an unpleasant when they are soldered to any wire. These low-quality PCBs are found in low-quality electrical products.

Next is a thin layer of copper foil laminated onto the board through adhesive and heat. In common PCBs, that is double-sided printed circuit boards, the copper film is laminated to both sides of the FR4. In lower-quality electronic devices, there may be only a single layer of copper foil even in the common PCBs. The number of copper layers may differ depending on the type of PCB. There are be less than 1 layer and there can be as many as 16 layers. Weight, expressed in ounces per square foot, is used to specify the copper thickness, which can vary.

The majority of printed circuit boards (PCBs) include 1 ounce of copper per square foot, however certain PCBs that handle extremely high power may utilize 2 or 3 ounces of copper. Copper is approximately 35 micrometers thick, or 1.4 thousandths of an inch, per square ounce.

The solder mask layer is the one that sits on top of the copper foil. The PCB's green color comes from this layer or in the case of SparkFun, red. This layer aids the user in soldering in the appropriate locations and eliminates solder jumpers.

The majority of the PCB in the example below has the green solder mask applied, masking the small traces while leaving the silver rings and SMD pads visible for soldering. Soldermask is usually green in color but it can be made in any color like red for SparkFun PCBs, for LilyPad PCBs are purple and for IOIO boards it is white.

• Signal types
• Current maximums
• Impedance characteristics
• Shielding considerations
• Capacitance limitations
• Voltages
• Location and type of circuit connectors and components
• Elaborate listing of net wire and schematic

A good PCB provider will team up with principle engineers to come up with a schematic using a software application like Allegro, Mentor PADSAR, or Altium. These platforms show the circuit planner how the board will function and the position in which the components need to be placed.

After the schematics are created, the design will be loaded by a mechanical engineer who will decide how the design will be incorporated into the electrical device.

Most of the time, the PCB provider and the customer will collaborate and come up with layout and design guidelines to place each component on the board. For instance, certain components cannot to connected close to another because electrical noise may be created in the circuit.

Usually, the PCB provider has access to data sheet information on each component where he will then place the data sheet in the mechanical layout and hand it over to the customer for finalization and approval.