Printed Circuit Board Design, Diagram and Assembly

Printed Circuit Board Design, Diagram and Assembly Process.

Printed Circuit Board Design or Printed Circuit Board (PCB) or Printed Wiring Board (PWB), is a board made out of insulating and highly heat-resistant insulating material such as fiberglass. These boards are also called substrates. A substrate or board may have only one single layer (single-layer circuit board) or more than one layer (multilayer circuit board). A conductive metal such as copper is used to make conductive pathway or traces to facilitate flow of electricity. Once these conductive traces are etched on the substrate, it is termed as “printed circuit board”.

PCB Design

PCB Design

History of Printed Circuit Board

The history of circuit boards dates back to mid-1930s, when an Austrian engineer Paul Eisler invented the PCB while designing a radio set. These radio sets were later massively used in World War II by United States. After this, the use and application of circuit boards because commercial in Electronic Companies.

These circuit boards are of no good use until electronic components are soldered. Electronic components can be either through-hole or SMD. Again the technology used to solder these components on the circuit board can be through-hole technology or Surface Mount Technology.

Soldering material may include solder in the form of solder wire, solder paste, solder balls for BGA (Ball Grid Array) and soldering flux.

PCB (Printed Circuit Board)

PCB (Printed Circuit Board)

Printed Circuit Board Design: Guidelines, Rules and Tools

As explained above, a printed circuit board is a board made of one or more layers of insulating PCB Material (fiberglass, ceramic, highly heat-resistant plastic or any other dielectric material) with conductive pathways etched with conductive metal such as copper.

During the PCB Manufacturing Process, traces of copper or any other conductor is etched off the board leaving only traces that are needed to mount / solder electronic components. Once all Basic Electronic Components are soldered on the circuit board and the board is ready for use, it is called Printed Circuit Assembly (PCA) or Printed Circuit Board Assembly (PCBA).

The current generic standard for printed circuit board design is IPC-2221A. IPC 2221A generic standard on printed circuit board design provides rules for manufacturing circuit boards and quality guidelines.

These information and guidelines is applicable for all Types of PCB including Single-Layer PCB and Multilayer PCB and information includes substrate information, material properties, criteria for surface plating, conductor thickness, component placement, dimensioning and tolerance rules and more.

Other circuit board designing standards are IPC-2220 and IPC-9592. It has to be noted that IPC and other standards will provide information on how to properly route the board.

For a perfect and reliable circuit board design, good knowledge and understanding of PCB layout techniques and basic understanding of circuit operation is needed. While designing a printed circuit board prototype, one must take proper care of the substrate material based of type of soldering technology and components to be used.

The width of the traces of the circuit board (circuit conductors) should be chosen wisely based on expected maximum temperature rise at the rated current and acceptable impedance. Other points to keep in mind with printed circuit board design are CTE, cost and dielectric properties. The designer needs to carefully balance the constraints of cost with reliability and performance needs. In addition, solder mask and via holes should also be selected carefully.

PCB Prototype

PCB Prototype

Printed Circuit Board Diagram

A circuit diagram is a diagram showing and explaining how and where electronic components will be mounted to achieve the target product. Each component on a circuit board diagram is represented by a circuit symbol. Making a circuit diagram prior to production is critical. It gives an idea of how the circuit will work and how to achieve the target product. A circuit diagram is essential for any new electronic product, device or gadget.

Circuit Symbol of Electronic Components

Circuit Symbol of Electronic Components

How to Draw a Circuit Diagram?

Drawing a circuit diagram is not that difficult if you know the basics. Here are some Tips, Tutorial and Guidelines:

  1. Learn and understand all the common symbols and abbreviations for electronic components to be used on the diagram.
  2. Using a ruler, draw connecting wires as straight lines. Use following symbols: ‘blob’ () at each junction between wires, label components (resistors, capacitors, diodes etc) with their values, the positive (+) supply should be at the top and the negative () supply at the bottom. Negative supply is usually labeled 0V, zero volts.
  3. For complex circuit diagrams, start from left to right. So that signals flow from left to right (inputs and controls should be on the left, outputs on the right).
PCB Layout

PCB Layout

Printed Circuit Board Assembly

PCB Assembly (Printed Circuit Board Assembly)

PCB Assembly

Mounting electronic components on the circuit board and getting it ready for use is what is called circuit board assembly. A Circuit Board Assembly Process may use through-hole assembly technology or surface mount technology (SMT) or a mix of both.

Once the circuit board is assembled with components it is ready for testing and finally to be assembled with the product. But it is not guaranteed that a circuit board assembly will give 100% zero defect production. There will be defects and these defect need to be reworked / repaired.

Video: SMT PCB Assembly Process

PCB Assembly Process Flow Chart (PCBA Process)

PCB Assembly Process Flow Chart (PCBA Process)

PCB Assembly Process Flow Chart (PCBA Process)

Printed Circuit Board Manufacturing Process (Step by Step Tutorial)

FAQs: PCB Design and Assembly

PCB design involves creating a schematic diagram of the electronic circuit, where components and their connections are represented. This schematic is then used to design the physical layout of the PCB. PCB design software helps engineers place components, route traces, and ensure proper electrical connectivity while considering factors like signal integrity and heat dissipation.

PCB assembly is the process of attaching electronic components to a PCB to create a functional electronic device. It involves soldering components onto the PCB using automated or manual methods. Surface Mount Technology (SMT) and Through-Hole Technology (THT) are common assembly techniques, each with its advantages based on component size and type.

PCB layout is crucial as it impacts the performance, reliability, and manufacturability of electronic devices. A well-designed layout minimizes signal interference, reduces noise, and ensures optimal heat dissipation. Careful placement of components and routing of traces help avoid defects and enable efficient production.

Here are some  Tips for Successful PCB Design:

  1. Plan Ahead: Define your project requirements and components early to guide your design process.
  2. Component Placement: Strategically place components to minimize trace lengths, reduce noise, and ensure efficient heat management.
  3. Signal Integrity: Maintain proper trace impedance, minimize signal crossings, and use ground and power planes to enhance signal quality.
  4. Keep It Simple: Avoid overcomplicating the design with unnecessary components or complex routing.
  5. Design for Manufacturability: Follow design rules provided by your PCB manufacturer to ensure your design is manufacturable and cost-effective.

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Santosh Das

Santosh, founder of this Electronics Tutorial Website, is an Electronics Geek, Blogger and Young Entrepreneur. He possesses vast experience in the field of electronics, electronic components, PCB, Soldering, SMT, Telecommunication, ESD Safety, and PCB Assembly Tools, Equipment and Consumables. Keep visiting for daily dose of Tips and Tutorials.

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