A PCB, which refers to a Printed Circuit Board, can be defined as an even board that does not conduct any electricity and is employed to give physical support and electrical connections to electronic components by means of conductive pathways, tracks, or signal traces. The pathways are done by etching concerned copper sheets, which are laminated to a non-conductive substrate material.
PCBs are an integral part of current electronics industry as they provide an easy and well-structured method for the transition of signals between different components, leading to better electronic devices’ performance.
They are found in numerous items that range from simple gadgets you can find at homes, for example, remote controls, to very complicated devices, for instance, computers, medical apparatus, vehicles, even planes, and rockets.
Types of PCB
Depending on the functional and design requirements of the PCB, there are a number of classifications of PCB’s:
- Single-Sided PCB: It is constructed with the use of one copper conductive layer only.
- Double-Sided PCB: It has conductive copper layers attached on both sides of the board.
- Multi-Layer PCB: A PCB with three or more layers of conductive material, which is ideal for complex electronics.
- Rigid PCB: These are rigid and are commonly used in long-lasting electronic devices.
- Flexible PCB: Bendable, making it suitable for use in tight spaces.
- Rigid-Flex PCB: A hybrid that combines rigid and flexible components for increased versatility.
- Metal Core PCB: A rigid PCB with an Aluminum Metal Substrate for high thermal conductivity
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We are a comprehensive electronics enterprise that is focused on offering Electronic Manufacturing Services (EMS) and Electronic Controls Design Services to different industry verticals, including industrial, medical, military, and aerospace—all the designs carefully crafted to fit your application.
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. Such patterns are permitted by this design to enable the fabrication of small sized, packed, and reliable electronic devices.
What are the key components of a PCB?
- Substrate (Base Material)
The substrate is the mostly non-conductive layer and serves as the base of the PCB giving it support and insulation. The common substrate is usually fiberglass (FR4) which is quite strong against external conditions. The substrate provides rigidity to the PCB, preventing it from bending or breaking easily.
Types of substrates
- Paper Phenolic
- Fibre-reinforced epoxy FR-1 to FR-4
- Teflon (PTFE)
- Alumina
- Kapton
- Ceramic
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:
- FR-4 is generally used in standard applications. Typical Tg is 135˚C. It also has a high-Tg version (150-210˚C) for automotive and military uses.
- CEM-1, CEM-2, and CEM-3 also work well in high-density applications. CEM-1 offers a Tg of 122˚C, CEM-2 has a Tg of 125˚C, and CEM-3 has a Tg of 125˚C.
- PFTE (Teflon Material) can be a good choice in high-frequency, microwave, and high-power applications with Tg anywhere from 160 to 280 oC.
- Polyimide as a substrate offers a Tg of 250˚C or more for high-power, high-frequency, and microwave situations. Polyimide substrates are also the best choice for flex circuits because FR4 substrates are rigid.
- Copper Layer
The design adds a layer of copper above the substrate, which is essential for making wires, otherwise called traces. These traces connect other parts of the PCB so that electric power is transferred. Single-sided PCBs have one copper layer, but double-sided and multi-layer PCBs have several 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.
- 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.
- Solder Mask
The solder mask is designed to be green in most cases but other colors exist. The solder mask is a layer of material that is applied to the PCB’s surface for protection. The primary purpose is to cover areas with copper traces that are likely to get short-circuited due to bridging. Basically, it helps to ensure that solder is applied only where it is required to be, such as on the bare surfaces where components will be mounted.
- Silkscreen
The silkscreen layer on the PCB consists of printed text, numbers, and illustrations. This helped the technicians or engineers in assessing the location of several elements like resistors, capacitors, and integrated circuits (ICs) on the board. 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 PCB works
- 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.
- 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.
- 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.
- 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.
- 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.
- Heat Management
Several printed circuit boards, more quantitatively the ones identified with high power or illumination, incorporate features for the management of heat. Heat sinks, vias, or thicker copper layers can alleviate excess heat and hence safeguard the components.
It can, therefore, be stated that the designs of the printed circuit boards are critical to achieving the maximum efficiency of a circuit board. Companies that specialize in electronic designing and manufacturing services, such as MicroLOGIX, understand the importance of optimizing such PCBs in order for the final electronic products to be of good performance.
PCB Designs
Board designing is a unique process as it can only apply to diverse situations, and therefore that calls for demand for accuracy.
Depending on the application, comprehensive PCB design layouts may include multi-layer PCBs, interface-controlled layouts, and designs that follow signal integrity principles.
Let us discuss these important aspects of PCB design
- PCB Layers
In cases where high-density and complex packages such as BGA or CSBGAs are in use, multilayered PCBs are the ideal solution. They typically help enhance the integrity of a signal and the dissipation of heat and also allow the use of ultra-small-sized parts.
For higher performance in a smaller package, MicroLOGIX manufactures designs with 16 layers of PCB circuitry depending on the application.
- Impedance Control Design
Impedance matching is of vital importance for high-speed digital and RF systems, meant to preserve the quality of signals and avoid loss or corruption of information, especially in the designs that operate at higher frequency ranges.
MicroLOGIX uses advanced tools and software to design PCBs with controlled impedance, which is very important in sectors like telecommunications and RF systems, where signal precision is one of the major factors.
- Differential Pair
Differential pair usage is one of the key factors in high-speed data applications because it has a great impact on signal integrity. This approach works by dividing the signal between two leads and thus reducing the amount of distortion.
At MicroLOGIX, the electronic engineers design the PCBs with special attention to the performance and application of differential pairs in high-frequency circuits.
This type of design is extremely important for PCBs in communications, data processing, and sound and video systems.
- Signal Integrity Compliance
Designs with low signal integrity lead to unpredictable operation or a complete device failure.
MicroLOGIX designs PCBs in a way that principles of signal integrity are preserved; therefore, your printed circuit board will be in line with EMC and other reliability requirements.
This analysis takes into account factors such as crosstalk (between conductors), ground, and signal-to-signal (time) delays, and ensures that your PCB operates properly in real-world conditions.
PCB vs PCM
The study of the difference between Printed Circuit boards (PCBs) and Printed Circuit modules (PCMs) highlights their respective roles and uses in electronic systems.
A PCB, or Printed Circuit board, is merely a flat board that consists of conductive tracks (also referred to as traces) interconnecting different electronic devices. It should be noted that PCBs do not possess any electrical components like resistors, capacitors, or ICs and instead function as a basic structure intended for mounting these elements.
In contrast, a Printed Circuit Module is a more complex structure containing not only just a blank layout of the electronics but also all the necessary wiring and components soldered on the circuit board, including the attachments of resistors, capacitors, and ICs to the PCB. In short, a PCM makes the PCB functional once the assembling is completed.
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, take a smartphone. One of the components of a smartphone is a circuit board (PCB) that connects other physical parts of your cellphone, like the battery, processor, and memory. Once all these elements are soldered together to the PCB, this stage is called PCM because it refers to a complete circuitry, already working and able to perform functions.
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 frequent objects in which PCB is utilized include:
- Consumer electronics like smartphones, tablets, and laptops.
- Medical devices like pacemakers, diagnostic machines, and wearable health devices.
- Automotives like engine control units (ECUs), navigation systems, and entertainment systems.
- Industrial equipment such as automation controllers, power converters, and communication systems.
MicroLOGIX has vast knowledge in the PCB design domain across the board, be it in defense & aerospace, healthcare, and telecommunications, among many others. The designs by the expert engineers are, however, high-performance, cost-effective, as well as meeting industrial requirements.
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!
Make your next electronic innovation a hit!