Table of Contents
In this article, we will go over how circuit boards work, and how they are used in medical industry. There is also a quick guide on how to disassemble the broken PCB and troubleshoot.
What Is a Circuit Board?
- Conductive layer: Made of copper, used to transmit electrical signals.
- Insulating layer: Made of fiberglass and epoxy resin, ensuring no electrical short circuits occur between different conductors.
How Does a Circuit Board Work?
- Current Path: When turned on, current flows from the power supply through the intended copper lines, passing through resistors, capacitors, and integrated circuits (ICs) to execute specific functions (e.g., amplifying signals, processing data, driving displays). It then reconnects to the power supply, completing the closed circuit.
- Signal Transmission: In addition to power delivery, copper traces transport a variety of electrical signals. These signals flow between components, allowing them to communicate and collaborate.
Detailed Workflow (With a Simple LED Circuit as an Example)
- Power Input: Electrical power (e.g., 3.3V) enters the circuit board’s power connector and is routed through copper traces.
- Current Limitation: Current passes through the resistor’s pad and into its body. The resistor confines current to its resistance value (e.g., Ω), preventing excessive current from harming downstream components.
- Driven Component: A safe current flows through copper traces to the LED’s anode (positive terminal), then to the LED chip.
- Functionality: This current causes the LED chip to emit light, hence performing the “illumination” function.
- Closed Loop Formation: Current exits the LED’s cathode (negative terminal), travels through another copper trace, and finally returns to the power supply’s ground wire (GND), completing a closed circuit.
Composition of a Circuit Board
- The base is the board itself, typically made of a non-conductive material such as fiberglass or epoxy resin. The stand provides a platform for mounting and connecting components.
- Traces are conductors on the board made of conductive materials, usually copper. The traces connect the components on the board to form a complete circuit capable of performing complex tasks.
- The components on each circuit board are themselves critical to making those boards work and transferring power or energy.
Table: Key Components and Their Functions in a PCB
| Component | Description | Analogy / Function Example |
| Substrate (Insulating Base) | Usually made of FR-4 fiberglass epoxy resin, it provides mechanical support and electrical insulation, preventing short circuits. | Acts like the foundation or skeleton of the PCB, holding everything together. |
| Copper Layer | A conductive layer etched into specific trace patterns to connect components and transmit signals or power. Found in single-, double-, or multi-layer PCBs. | Works like electrical highways that carry current between components. |
| Pads | Exposed copper areas on the board where component leads are soldered. | Serve as connection points — like sockets that anchor each component. |
| Silkscreen Layer | Printed text and symbols (e.g., R1, C2, IC3) that label component positions and orientations. | Functions as the labeling system or map legend of the PCB. |
| Solder Mask | A green (or other colored) insulating coating covering copper traces to prevent short circuits and oxidation during soldering. | Acts like a protective shield or skin for the copper layer. |
| Vias | Metal-plated holes that connect copper traces between different PCB layers. | Serve as vertical tunnels allowing signals to travel between layers. |
| Electronic Components | Resistors, capacitors, ICs, and other devices soldered onto pads to perform circuit functions. | The organs or brain of the circuit — enabling it to process and function. |
How Do These Parts Work on a Circuit Board?
• Resistors are one of the most critical components for circuit boards to work because they transmit current to generate voltage and dissipate power in the form of heat.
• Transistors are used to switch or control electronic signals on a circuit board. During the life of a circuit board, other parts of the board sometimes require more energy or charge.
• Capacitors retain charge within the circuit board and release it when this power is needed elsewhere.
• Inductors store energy within the board in the form of a magnetic field when current flows through them. They are often used to block signals within the circuit board, such as interference from other electronic devices or equipment.
• Diodes are devices that allow current to flow in one direction but not the other, and can be used to stop current from flowing through the board in the wrong direction, which can lead to damage.
How to Take Troubleshooting
When Circuit Boards Do Not Work?
If the PCB does not work, there are several steps you can take to troubleshoot.
1. Identify the symptoms: Observe and describe the symptoms, such as no power, no output, wrong output, or erratic behavior. The symptoms can help to narrow down the possible causes and locations of the failure.
2. Locate the fault: Use various tools and methods, such as visual inspection, multimeter, oscilloscope, or logic analyzer to inspect the circuit board. The board is checked for any signs of physical or electrical damage, such as cracks, burns, or shorts, and the components and the traces are measured for their values, voltages, currents, or signals. The fault is located by following the circuit from the power supply to the input and output ports, and isolating the faulty component or trace.
3. Repair or replace the fault: Depending on the severity and type of the fault, the board is repaired by using various tools and methods, such as a soldering iron, desoldering pump, or solder wick. The faulty component or trace is removed, cleaned, or reconnected. The board is replaced by ordering a new board from the manufacturer or a supplier, or by making a new board from scratch.
4. Verify the solution: The board is tested again for functionality and performance, and the problem is verified to be solved. The circuit board is checked for any errors or defects, and the components and the traces are measured again for their values, voltages, currents, or signals. The PCB is then installed in the device and operated normally, and the results are observed and compared with the expected results.
In conclusion, PCBs can fail for various reasons. Troubleshooting circuit board failures involves identifying, locating, repairing, or replacing the fault, and verifying the solution.
If you would like to learn more about how PCBs work, what they are made of, or how ELEPCB can help you with your project, please contact us for more information. We have a good industry reputation and years of knowledge with PCB manufacture. Work with us to design PCBs that ensure reliability and precision, and take your product to the next level.
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