A PCB switch works by physically connecting or disconnecting pathways made of copper on a Printed Circuit Board (PCB), allowing or stopping the flow of electricity.
At its core, a switch is a component that controls the flow of electrical current in a circuit. On a PCB, this function is achieved by mechanisms that interact directly with the board's conductive elements.
The Foundation: The PCB
A Printed Circuit Board provides the base for electronic components. It has a special layer like a piece of fabric covered in copper. This layer is called a “copper-clad laminate layer.” This copper layer acts as the wiring for the circuit, forming specific patterns or traces.
The Role of Copper
As highlighted by the reference, this copper layer can carry electricity when the switch is turned on, and the pathway is complete. It's essentially like the road that electricity travels on. When a circuit is designed, specific copper traces are laid out to connect different components, including the points where a switch will be placed.
The Switch Mechanism
A PCB switch typically has two or more terminals (metal pins or contacts) that are soldered onto the copper traces of the PCB. The internal mechanism of the switch is designed to make or break a connection between these terminals.
Here's a simplified breakdown:
- "Off" State: In the off position, the internal contacts of the switch are open. This means there is a gap between the conductive parts that would normally connect two copper traces on the PCB. The electrical pathway is broken, and electricity cannot flow between those points.
- "On" State: When the switch is actuated (pressed, slid, flipped, etc.), the internal mechanism moves conductive material to bridge the gap between the terminals. This creates a complete electrical connection between the corresponding copper traces on the PCB. The pathway is now complete, allowing electricity to flow through the switch and continue along the copper road to other components.
Think of it like a tiny bridge that can be lowered to connect two roads (copper traces) or raised to disconnect them.
Types of PCB Switches
There are many types of switches designed to be mounted directly onto PCBs, each with a different physical mechanism for making and breaking the connection:
- Tactile Switches: Small push-button switches commonly used in electronics. Pressing the button causes a dome-shaped metal contact to deform and touch the PCB pads, completing the circuit.
- Slide Switches: These have a small slider that moves horizontally. The slider's internal contact connects different sets of terminals as it moves, changing the circuit configuration.
- Toggle Switches: Feature a lever that is flipped. The internal mechanism moves contacts to either connect or disconnect terminals based on the lever's position.
- DIP Switches: (Dual In-line Package) Small switches often used for configuration settings, typically found in groups.
Regardless of the type, the fundamental principle remains the same: the switch physically controls whether specific copper pathways on the PCB are connected, thereby regulating the flow of electricity.
How the Connection Works
When a switch connects, it effectively bridges two points on the copper traces. This allows current to flow from one point, through the switch's internal contacts, to the other point on the trace.
| Switch State | Electrical Pathway | Electricity Flow |
|---|---|---|
| Off | Broken / Open | Stopped |
| On | Complete / Connected | Allowed |
This simple make-or-break action is fundamental to controlling functions in electronic devices, from turning a device on/off to selecting different modes of operation, all facilitated by the switch interacting with the conductive copper layers of the PCB.
