A Comprehensive Guide to Switch Types in PCB Design

Switches are essential components in PCB design, responsible for controlling the flow of electrical current within a circuit. They act as mechanical or electronic devices that can open or close circuits, enabling or disabling specific functions. Whether you're designing a consumer electronics device, an industrial machine, or a medical instrument, the right switch type is crucial for the functionality, reliability, and user experience of your product. In this guide, we'll explore the different types of switches commonly used in PCB design and how they are different from a PCB Switch.

What is a PCB Switch?

These are the unique switches that use a printed circuit board as the special circuitry that makes them work. The best possible way to get your hands on a PCB switch is a TV remote. When we talk about a PCB switch, we talk about a part controlling an electrical pathway. It does this by either connecting the pathway or disconnecting it. For example like a bridge - when the switch is on, it connects the bridge pathway and lets the current flow. When turned on it disconnects the pathway by lifting the bridge and current can not flow.

The PCB switches use a special mechanism, the switching circuitry is printed on the PCB itself and by pressing the switch it connects the bridge and lets the electricity flow. PCB switches enable simple functions and activation in devices. These versatile components enhance usability and functionality in combination with other types of switch like push buttons, toggle switches, and more.  PCB switches also provide smooth operations and improve user experience in devices across industries due to their durability and dependability.

Working of a PCB Switch:

While there are other types of electrical switches available, in some designs PCB switches

The coating refers to the black part on the copper PCB, which is responsible for good connection of the switch. This is a low resistance carbon which is used to bridge the gap between the PCB. The pressing mechanism also has the same carbon, when it gets in contact with each other the bridge is connected and electricity starts flowing.

These connections can be made of highly conductive materials, such as copper, to provide a lower level of electrical resistance. But then in the pressing mechanism we have to use a conductor layer. You can choose gold-plated PCB switches, for example, that feature a plated layer of gold.

How to Design a PCB Switch?

To make a PCB switch, you’ll need a computer with design software (like Eagle, Altium, or EasyEDA), a PCB manufacturing service, and essential electronic components like resistors, capacitors, and the battery. Here’s how you make your own PCB switch:

Step 1: Define Your Requirements

Begin by outlining the purpose of your PCB switch. Determine your application’s voltage and current requirements to ensure your switch can handle the electrical load.

Step 2: Designing of the Footprint and Symbol

Symbol: The symbol should represent the switch’s electrical function. Typically, it includes pins for connections to the PCB and a representation of the switch’s behavior (e.g., normally open or normally closed). Label each pin clearly and ensure it matches the pin configuration in the footprint.

Footprint: Usually we start by checking the manufacturer's datasheet for the switch dimensions. Here we can plan the footprint accounting to the sizing requirements defined in step 1. Ensure there’s enough clearance around the switch and between the traces.

Step 3: Plan the PCB Layout and trace layout

Create a layout for your PCB that accommodates the switch and its associated components. Use PCB design software to draw the circuit traces, component placements, and connection points. Ensure sufficient space around the switch for easy operation. Measure the dimensions of the chosen switch, considering its length, width, and height. These measurements are essential for creating the correct PCB cutouts and designing any housing or casing for the switch. Pay attention to trace width and spacing to ensure proper current handling and prevent signal interference. Keep the traces as short and direct as possible.

Step 4: Create Cutouts and Mounting Holes

Incorporate the switch cutouts and mounting holes into your PCB design. These features allow the switch to be securely attached to the PCB. Double-check the dimensions to ensure a proper fit.

Step 5: Add Supporting Components

Integrate any necessary components around the switch, such as resistors, capacitors, or LEDs. Ensure these components complement the switch's function and adhere to your design specifications.

Step 6: Verify Connectivity and Circuitry

Before moving forward, use the PCB design software to verify the connectivity of your circuit and inspect the layout for any errors. This step helps prevent issues that could arise during manufacturing or testing.

Step 7: Finalize Design and Production

Incorporate any changes based on testing and fine-tune your PCB switch design. Once you’re satisfied with your prototype, finalize the design and prepare the files for manufacturing. Choose a reliable PCB manufacturing service and submit your design files for production.

Other Main Types of Switches Used in Circuit Design

1. Tactile Switches

Tactile switches are commonly used in consumer electronics, especially in handheld devices like smartphones, remote controls, and keyboards. These switches offer a noticeable "click" when pressed, providing feedback to the user that the switch has been activated. Tactile switches are small, reliable, and cost-effective, making them ideal for high-volume production and compact designs. Having applications in wearable and remote control devices.

Key Features:

• Low profile
• Tactile feedback
• Compact size

2. Push Button Switches

Push button switches are among the most familiar types of switches, found in devices ranging from calculators to machinery control panels. These switches can be momentary or latching. Momentary switches return to their original state after being pressed, while latching switches stay in their new state until pressed again. They are used as power buttons in devices and control panels.

Key Features:

• Simple mechanism
• Momentary or latching options
• Easy to integrate

3. Slide Switches

Slide switches move a contact back and forth, which opens or closes a circuit. These switches are durable and can be used in various devices that require a simple, manual operation to change states. Having main application in devices like audio equipment, mode selection in gadgets.

Key Features:

• Reliable mechanical operation
• Multiple positions (e.g., On/Off/Auto)
• Durable and easy to use

4. DIP Switches

Dual In-line Package (DIP) switches are a series of small switches used for setting up configurations or options in a device. Instead of needing to reprogram or modify a PCB, DIP switches allow for manual configuration changes. These switches are popular in both older electronics and modern devices requiring quick reconfigurations. Having applications in digital devices configuration and address setting for network devices.

Key Features:

• Configurable
• No need for software or reprogramming
• Simple setup changes

5. Rotary Switches

Rotary switches allow users to select different positions by rotating a knob. Each position connects different circuit paths, making it a versatile option for applications where multiple modes or outputs are required. These switches can be found in multi-mode devices and audio equipment.

Key Features:

• Multiple selectable positions
• Precise control
• Rugged and durable

6. Toggle Switches

Toggle switches are widely used for their reliability and simplicity. They feature a lever that can be flipped between two or more positions to open or close a circuit. Toggle switches are often used in applications where users need to easily control functions with a simple, manual action. Having huge demand in automotive systems and consumer appliances.

Key Features:

• Easy to operate
• Multiple positions
• High durability

7. Rotary Encoders

While not technically switches, rotary encoders are used for precise control in many electronics. They convert the angular position of a shaft into digital or analog signals, making them perfect for devices that require precise adjustments. Having main application in audio/video control systems and UI design.

Key Features:

• Precise rotation detection
• Infinite rotation capability
• Digital and analog output options

Conclusion

Switches play a pivotal role in determining the functionality and usability of your PCB design. Printed circuit board switches have increasingly become instrumental in the design and operation of circuit boards. Therefore, if you are a circuit board designer, it becomes critical to consider the PCB switch aspects deliberated upon in the article. You can choose the right one depending upon the project requirements, ensuring that your design is efficient, reliable, and user-friendly.