What is PCB (Printed Circuit Board)? Types and Applications

Types of PCB

PCBs are classified into several types based on their functional and design requirements:

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How does a circuit board work?

PCBs are the foundation of most modern electronics. It provides a platform to mechanically support and electrically connect components. Conductive copper pathways etched onto a non-conductive board enable PCBs to allow electrical signal flows between components such as resistors, capacitors, and microchips. This design makes it possible to create compact, efficient, and reliable electronic devices.

What are the key components of a PCB?

To understand how a printed circuit board works and why it’s so crucial in electronics, it’s essential to look at its core elements. Each of these components contributes uniquely to the PCB's functionality and durability. The key components include:

1. Substrate (Base Material)

The substrate is the PCB's base layer, which provides both structure and insulation. It is typically constructed of fiberglass (FR4), which provides durability and resistance to environmental factors. The substrate provides rigidity to the PCB, preventing it from bending or breaking easily.

Guidelines for PCB Material Choice

Clearly, the cost of substrate and laminate materials varies quite a bit. But it pays to choose the right materials from the outset rather than suffer the shame of costly PCB failures.

Here are a few general suggestions that can serve as a starting point for picking materials for specific substrate/laminate applications:

2. Copper Layer)

Above the substrate lies a thin layer of copper, which is crucial for forming the electrical pathways (traces). These copper traces link the different components on the PCB, enabling electrical signals to flow between them. Single-sided PCBs contain only one copper layer, whereas double-sided or multi-layer PCBs may contain multiple copper layers.

The thickness of the copper layer varies for different current ratings. Either they come prefabricated from the laminate suppliers or deposited during the PCB manufacturing process. Typical copper thicknesses are 35 and 70 microns.

3. Tg of the PCB

Substrate or laminate’s ability to handle higher temperatures is an important characteristic of PCBs. High heat can damage the board, so the substrate’s thermal characteristic has to be higher than the heat generated.

Tg (glass transition temperature) defines the temperature of a substrate material. In other words, it's the point at which a PCB loses its rigidity.

For high-performance boards, the Tg is usually higher than 170˚C. Standard PCBs have a Tg of 130˚C. Also, it’s important to specify the Tg to match the assembly process being used. A Tg with a minimum of 170˚C is typically used in automotive or military applications and is also recommended for lead-free assembly.

4. Solder Mask

The solder mask is typically green but can come in other colors too. It is a protective coating that covers the surface of the PCB. Its main job is to shield the copper traces from accidental short circuits by providing insulation. Essentially, it ensures that solder is placed only in the necessary spots, like the exposed areas where components will be attached.

5. Silkscreen

The silkscreen layer on the PCB includes printed text, numbers, and symbols. This helps the technicians or engineers identify and understand the placement of components such as resistors, capacitors, or integrated circuits (ICs). This labeling simplifies the jobs of assembling, repairing, and debugging procedures.

These components work together to form a functional PCB, allowing complex circuits to be housed in small, efficient packages. Without these components, building dependable and organized electronic circuits would be extremely difficult.

A Step-by-Step Breakdown of How a PCB Works

1. Power Supply

Electrical power, typically from a battery or an external power source, flows into the PCB. This power is routed to the required components via copper traces, providing them with the necessary voltage and current.

2. Electrical Connections via Copper Traces

Traces, or conductive copper pathways on the PCB, replace traditional wiring. These traces act as roads, directing electrical currents to the appropriate components on the board. Traces, unlike wires, are compact and precisely designed to save space and avoid interference.

3. Component Interaction

Resistors, capacitors, transistors, and microchips are soldered onto the printed circuit board. Each component serves a specific purpose, such as managing current flow, storing energy, or processing data. The copper traces ensure that these components are connected in the proper order, allowing them to function as intended.

4. Signal Transmission

Electrical signals are transmitted between digital PCB components (such as microcontrollers or memory chips) to perform specific tasks, such as program execution or motor control. The traces are designed to transmit these signals with minimal distortion or delay.

5. Grounding and Protection

Ground planes or copper layers are frequently used on PCBs to serve as circuit reference points. Grounding helps to prevent electrical noise, interference, and static buildup, all of which can disrupt circuit performance. Furthermore, features such as the solder mask and silkscreen help to protect the board and ensure proper component placement.

6. Heat Management

Certain printed circuit boards, particularly those used in high-power or lighting applications, include heat management features. Heat sinks, vias, or thicker copper layers can help dissipate excess heat and protect the components.

To summarize, PCB designs play an important role in maximizing the output of a circuit board. Electronic manufacturing and design companies like MicroLOGIX specialize in optimizing PCBs that are designed for maximum efficiency and reliability, ensuring that your electronic products perform at their best.

PCB Designs

Designing a PCB is a highly specialized, application-specific task that requires precision and expertise. Comprehensive PCB design layouts, including multi-layer PCBs, impedance-controlled designs, and signal integrity compliance are important depending on the application.

Let's explore these critical aspects of PCB design:

1. PCB Layers

When high-density and complex packages like BGA or CSBGAs are involved, multi-layer PCBs are the preferred choice. They usually help to improve the signal integrity, and heat dissipation and facilitate the use of ultra-miniature components.

MicroLOGIX designs PCBs with up to 16 layers depending on the application for higher performance within a compact form factor.

2. Impedance Control Design

Implementation of impedance control in high-speed digital and RF circuits is crucial for maintaining signal integrity and preventing data loss or interference, particularly in designs operating at high frequencies.

MicroLOGIX utilizes advanced tools to create PCB designs with impedance control, a critical factor in industries such as telecommunications and RF systems where precise signal transmission is imperative.

3. Differential Pair

In high-speed data applications, the use of differential pairs is crucial for ensuring signal integrity. By transmitting signals across two separate traces, this technique effectively minimizes distortion.

The electronic circuit designers at MicroLOGIX meticulously incorporate differential pairs into our PCBs, guaranteeing optimal performance and efficiency in high-frequency circuits.

This design element is especially critical for PCBs used in communication systems, data processing units, and audio-visual equipment.

4. Signal Integrity Compliance

Poor signal integrity can cause devices to function unexpectedly or completely fail.

MicroLOGIX PCB designs conform to stringent signal integrity standards to guarantee that your printed circuit board (PCB) meets the required EMC and other criteria for dependability.

The thorough analysis considers aspects like crosstalk, grounding, and signal timing to guarantee that your PCB functions efficiently under practical circumstances.

PCB vs PCM

The comparison between Printed Circuit boards (PCBs) and Printed Circuit modules (PCMs) emphasizes their distinct functions and applications within electronic systems.

A Printed Circuit board (PCB) is a bare board with conductive pathways (traces) typically made of copper that connect various electronic components. However, PCBs do not include any components such as resistors, capacitors, or ICs; they serve primarily as a platform for hosting these components.

On the other hand, a Printed Circuit Module (PCM) is a fully assembled module that includes both the PCB and electronic components (resistors, capacitors, ICs, etc.) already mounted and connected to the PCB. The PCM brings the PCB to life, enabling its functionality after component integration.

What is PCB and PCM key difference?

If we summarize the points discussed earlier, we know that PCB focuses on the physical board where electronic components are later mounted, whereas PCM includes both the PCB and the assembled electronic components, forming a ready-to-use module.

For example, a smartphone may use a PCB to connect components such as the battery, processor, and memory. Once all of those components are soldered to the PCB, it becomes a PCM, which is a fully functional circuit capable of performing tasks.

Understanding this distinction is critical for determining whether you require a PCB for custom assembly or a complete PCM ready to use in a product.

Examples of PCB

Almost any electronic device you can think of contains a printed circuit board. Some common examples where PCB is used include:

MicroLOGIX has extensive experience in designing PCBs for all sectors, such as defense & aerospace, healthcare, telecommunication, and many more. The expert engineers ensure that the designs are high-performance, cost-efficient, and meet industry standards.

Would you choose MicroLOGIX for PCB design?

MicroLOGIX is a well-known player in the electronic manufacturing services (EMS) and design industry, specializing in customized solutions for all your electronic requirements. From the initial idea to the finished product, we create custom PCB designs using advanced tools to guarantee top-notch performance and durability. We prioritize punctuality, ensuring timely deliveries without sacrificing product quality. And most importantly, our PCBs meet international standards such as RoHS and IPC.

Are you looking for high-quality, reliable PCBs that are precisely designed? Then MicroLOGIX may be your best option!

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