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The PCB Design Resource Channel is a worthwhile location that provides electronic engineers and designers with top-notch resources and tools to design printed circuit boards. In this section, the latest guides in design, tutorial videos, software tools, example projects, and best practices are organized together for reference on how best to go about optimizing the design process for better work efficiency and product quality.

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Your comprehensive PCB knowledge resource. Explore in-depth guides on PCB design, material selection, fabrication techniques, and industry trends. Empower your PCB expertise today! 

PCB Resources - PCB Expert Manufacturing - PCBX

PCBA Resources

PCBX: Master the art of PCB assembly. Delve into expert guides on PCB assembly processes, techniques, and quality control procedures. Elevate your PCB assembly skills now! 

PCBA Resources - PCB Expert Manufacturing - PCBX

Discrete Components for Analog Circuit Performance

In an analog circuit, the analog signals are used to convert and process analog signals from sensors, audio devices, medical instruments and RF devices; any small changes in the accuracy or noise or temperature of the analog signals can make an entire system useless. Integrated analog chips provide compact, ready-to-use circuit functions, but have fixed values of internal parameters, mismatching of components and limited power handling. These gaps are filled by discrete components such as resistors, capacitors, transistors, diodes and inductors, which allow the engineer to have complete control of the performance of the circuits. Discrete parts provide a more precise selection, intentional matching and optimized PCB layout that standard ICs cannot provide, resulting in targeted optimization. This article describes the advantages of discrete components on improving analog circuit reliability, suppressing noise, minimizing thermal drift, and increasing precision.<h3>Core Optimization Advantages of Discrete Components</h3>Control of precision is the most basic of strengths offered by discrete devices. Typical on-chip integrated resistors and capacitors are available with a tolerance of ±10% and a tolerance of ±0.1% or even ±0.001% for the discrete resistors with a pm of ±5 ppm/°C for the resistors. This tight tolerance removes millivolt-level signal errors from the circuit, which can affect weak sensor readings in voltage dividers and op-amp feedback networks. Instead of the fixed-function ICs, designers are free to select discrete components that have precise resistance, capacitance, or power values to satisfy specific gain, cutoff frequency and impedance needs.<img src="https://img.pcbx.com/dev/file/image/article/20260730/ad59c9ddc25f4326b67b584d10758c0d.jpg" alt="Core Optimization Advantages of Discrete Components-PCBX" data-href="" style="width: 100%;"/>Discrete components also significantly enhance the noise characteristics of low noise amplifiers (LNAs) and front end signal chains. The thermal noise generated by metal-film discrete resistors can be significantly reduced compared to carbon resistors, and noise figures of less than 0.5 dB are achievable with discrete FETs for RF preamplifiers. Low value discrete resistors can be used at input stages to reduce thermal noise levels and discrete LC filters can be used to remove unwanted interference without compromising on the flatness of the signal. Multi-stage filtering for audio, data acquisition and communication systems can be fully adjusted using a discrete RC/LC network, while an integrated filter IC causes users to become locked into predetermined cutoff frequencies.A further important optimization advantage is stability to temperature and aging. The drift of integrated components is very high over large temperature ranges; the drift of discrete passive components with low value of thermal coefficient is maintained within the industrial operating temperature range of -40°C to 125°C. If the discrete components to be matched are grouped together on PCBs, the common-mode environments of the components will be the same, allowing differential amplifiers that use balanced resistor pairs to maintain high common-mode rejection ratio (CMRR) to maintain minimal differential drift. A set of pre-matched and discrete transistor pairs reduces error to less than 1% due to a 2 mV mismatch between the base-emitter voltage of the two transistors.Discrete active components are used for high voltage, high current designs and are superior to on-chip devices in high power analog designs. When paired with low-ESR discrete capacitors, discrete MOSFETs and power diodes carry out significant regulation in linear regulators and switching power supplies helping to minimize the amount of heat developed on the chip and decrease output voltage ripples. This flexibility is well suited for industrial power control applications and automotive analog modules which require high load tolerance.<h3>Practical Discrete Optimization Techniques for Analog Circuits</h3>Precision matching, drift suppression and layout optimization are the three fundamental discrete component strategies that engineers use to improve analog performance.One of the first advantages of component matching is that it eliminates circuit imbalance. Either designers use high precision meters for sorting discrete resistors and transistors to insure that sets of closely matched parts are grouped together, or factory-made sets of matched resistors. Differential amplifier circuits use matched discrete resistor pairs, which keep gain error of less than 0.2%, compared with errors of up to 2% when using random resistors. This directly boosts the CMRR by more than 20 dB for weak biomedical sensor signals.Secondly, the choice of components restricts the long-term drift. The use of low temperature-coefficient resistors and stable film capacitors reduces value changes by 0.1% across a 100°C range in temperature. Thermal isolation layout can be used to shield sensitive discrete components from heat generating power devices, and negative feedback networks of discrete resistors can actively counteract voltage reference circuits that exhibit residual drift.Thirdly, PCB design optimizes the performance of discrete components. A digital zone and analog zone separation allows discrete signal chains to remain unaffected by digital switching noise. Special discrete feedback resistors and filter capacitors are located within millimeters of amplifier pins to reduce signal traces and parasitic capacitance. Short ground return loops around individual LC filters also minimize electromagnetic pickup thus maintaining the integrity of the signal in high frequency analog signals.<img src="https://img.pcbx.com/dev/file/image/article/20260730/fb8da75fa5094e4e9bf4ad719c80a8d5.jpg" alt="Balancing Discrete and Integrated Design-PCBX" data-href="" style="width: 100%;"/><h3>Balancing Discrete and Integrated Design</h3>Just as with analog ICs, a discrete application is not a complete substitute, hybrid design provides the ultimate result. To reduce circuit size, board size, and implement the core circuit logic, engineers incorporate a number of integrated circuits, then add discrete components to solve IC performance problems at precision-critical points, in low-noise circuits, or to boost power. This is a blended design, that allows for compact manufacturing and high customizability without sacrificing anything to the extremes of fully integrated or fully discrete, single-scheme designs.Despite the advancement of integrated analog chips, such as one-chip temperature transducers, discrete components still have their place and play an irreplaceable role in boosting the performance of analog circuits, overcoming the shortcomings of precision, noise and stability of analog integrated chips. Designers choose low-drift, tightly controlled discrete components, ensure careful component matching and optimize PCB layout to ensure ultra-accurate signal processing and low-noise amplification in consumer, medical, industrial and RF hardware systems, for consistent long-term performance. Discrete component optimization is a key skill for engineers who need high-performance, reliable analog hardware with flexibility in customization.When translating your discrete analog schematic into manufacturable printed circuit boards and assembly, PCBX provides precision PCB fabrication, layout review services and component placement that maximize the performance of your discrete circuit designs.

Discover how discrete components improve precision, noise performance and stability to optimize high-fidelity analog circuit design alongside integrated ICs.

How Discrete Components Elevate Analog Circuit Performance

Understanding Countersink Holes in PCB Design

The printed circuit board (PCB) is the backbone of the electrical function of all modern electronics hardware and mechanical mounting characteristics are critical to both circuit performance and assembly. Countersink holes are precision-machined tapered holes that help flat tapered heads of the screws to sit flush or slightly below the surface of the PCB, as compared to the standard straight through-holes and the cylindrical counterbore holes. These holes are usually ignored in the schematic design stage, but they will directly affect assembly clearance, mechanical strength, electrical safety, and product size. With the development of miniaturization, high-density layout, and long-life operation of electronics, the understanding and rational design of countersink holes are becoming an essential ability for PCB engineers. This article reviews the basic value of countersink structures, discusses the two main types of countersinks, presents essential design guidelines and explains some of the typical differences between countersinks and counterbores.<h3>Core Importance of Countersink Holes in PCB Design</h3>Countersink holes provide multiple level functional benefits that address common assembly and reliability points:First, they make best use of the space available within the device. When using traditional protruding screw heads, surface-mounted components are extruded, shorted out, or fail to assemble due to collision with the protruding screw heads. Embedded fasteners remove vertical obstructions, which enables high component density for wearables, miniature sensors and smartphone motherboards.Secondly, they increase the mechanical stability during vibration and thermal cycling. A tapered countersink surface fully engages matching screw heads, and distributes locking pressure around the hole. An important feature of straight holes is that they only bear load on a narrow ring edge, thus focusing the stress and leading to substrate cracking, delamination or loose fasteners over time, which is crucial for automotive and industrial control electronics that are constantly subject to shock.Thirdly, they help to minimize the risk of electrical failure. Risks of contact with nearby copper traces, pads and conductive shielding layers are present with exposed metal screw heads.There are risks of contact with nearby copper traces, metal pads and conductive shielding layers with the metal screw heads being exposed. Recessed countersunk fasteners reduce the chance of conductive exposure and reduce the probability of shorting; flat board surfaces allow easy and completely flush installation of EMI shielding gaskets for improved electromagnetic compatibility.Fourth, they optimize mass production and enhance beauty. Countersink tapers provide self centering positioning for automatic screw locking, cutting assembly deviation and production cycle time. For consumer electronics products that have exposed parts of the circuit, the flush screw installation provides a neat, uniform appearance which meets industrial appearance standards.<img src="https://img.pcbx.com/dev/file/image/article/20260728/5b3cf9623ca64d45a809bb7be2cc2a04.jpg" alt="Importance of Countersink Holes in PCB Design-PCBX" data-href="" style="width: 100%;"/><h3>Main Types of Countersink Holes for PCB Applications</h3>There are two main variants of the countersink that are used in industry, each with different geometry and applications:V-Countersinks (Conical Countersinks)V-countersinks are given their name because they are symmetrical tapered walls which are machined into standard countersink holes. Standard angles are 82° for imperial inch screws and 90° for metric M-series flat-head screws, and are only available for special micro fasteners for 60° and 120°.This is the most popular type in use for general electronics. The smooth, continuous taper uses minimal material removal to provide complete flush seating of screw heads, resulting in a balance of manufacturing costs and performance. It is suitable for consumer electronics, household control boards or precise instruments for laboratories where complete flatness is needed. Advantages: easy CNC processing, wide applicability for fasteners, uniform distribution of stress on the hole edge.T-Countersinks (Counterbore-Type Recesses)A 'T-counterbore' is often called a counterbore hole as it has a cylindrical vertical recess and a flat-bottom rather than a true conical taper. T-countersinks provide greater depth for the screw head to extend past the board surface and are designed to accept cylindrical socket-head cap screws completely below the board surface where a V-countersink would only offer space to hide the screw head level with the board surface.This design emphasizes vertical space for multi-layer assemblies and high density industrial equipment. The flat base provides excellent shear resistance to the hardware in extreme mechanical loading, and vertical side walls ensure accurate screw alignment in automated assembly. Typical applications are multi-board stacked modules, factory automation controllers, power supply PCBs where secondary components need to be mounted above fastener locations.Critical Distinction: Countersink vs CounterboreDesigners often mix up the two and use incompatible fasteners because of their geometry. Countersinks have angled tapered walls, used only with tapered flat-head screws, and counterbores (T-countersinks) have straight vertical walls that are optimized for cylindrical socket-head screws. The uneven stress due to mismatching hole screw combinations leads to an incomplete flush mounting and long-term screw loosen.<h3>Practical Design Guidelines for Countersink Holes</h3>If the manufacturing and reliability rules are not adhered to, then fabrication defects will occur:Minimum Copper clearance: For the major diameter countersink, it needs to be at least 0.2mm from other traces, pads and copper pours to avoid copper peeling when drilling.Match angles to fasteners: The mixed-angle countersink layouts mean that no two angles on a single board can be different, as it will lead to varying contact and areas of stress.Adjust the counter sink depth according to board thickness: The thickness of substrate that remains under the counter sink after precision machining should not be less than 0.2 mm to ensure the structure strength and reduce through board phenomenon.Clearly define machining direction to avoid assembly misalignment if countersinking is required: If there are parts whose direction of machining is counter-sinking top or bottom of the component, then clearly define it to avoid misalignment in assembly.Allow tolerance in assembly for high vibrating equipment: Open the diameter of the countersink opening a little bigger than usual for the equipment that is very vibration.<img src="https://img.pcbx.com/dev/file/image/article/20260728/c6d55d83e6d848628283d1bed863e67b.jpg" alt="Design Guidelines for Countersink Holes-PCBX" data-href="" style="width: 100%;"/>Countersink holes are much more than just a part of a PCB's structure; they serve as an important link between the electrical layout and mechanical assembly. V-countersinks are designed for consumer hardware that has tight specifications for a flush surface and do not need to be expensive.V-countersinks are used when the surface finish must be flush in a tight consumer product application where cost is a driver. The optimized countersink geometry helps optimize space use, vibration resistance, electrical safety, production efficiency and thus directly extends the service life of finished electronic devices.For boards that require specific countersink characteristics, a trusted PCB manufacturer will ensure that the design is executed with precision, meeting DFM requirements. PCBX offers professional countersink machining services for all types of boards with all types of fasteners, producing the best PCB with consistent quality and free of defects, perfect for prototype testing and mass batch production.

Learn PCB countersink hole types, core functions and critical DFM best practices to improve assembly reliability of your circuit boards.

A printed circuit board can successfully pass all simulations and yet fail on the assembly line. Most costly PCB design errors occur here: where the design and the actual production vary. When creating a design, the first time you design it properly is when you think about how the board will be built, tested, and used in the field.<h3>Component Footprint and Land Pattern Errors</h3>The common mistake and costs associated with this is when the schematic symbol is not consistent with the actual footprint on the board. If the size of the land pattern is too small or too large for the package size, then it can lead to solder bridging or under-wetting during reflow. This is especially a challenge on a fine pitched component such as a QFN or BGA, where the geometry of the pads has very little tolerance. Designers are cautioned to check footprints against manufacturer's datasheets, not against generic library parts, and be sure to check the correct pad size based on the thickness of the solder paste stencil used in the manufacturing process.<h3>Inadequate Component Spacing and Clearance</h3>When the designer is under pressure to reduce the size of the board, components may be closer together than the assembly process can keep them. Taller components may cause shadowing effects during reflow, where the hot air or infrared is being applied to the shorter components and is being blocked from the taller components by the lack of clearance. The close spacing of fine-pitch ICs and other components also allows little room for placement accuracy, which may result in soldering bridges or tombstoning. As a general principle, the clearance should be based on the assembly process being employed, and the deviation from the clearance should be reported as early as possible, not at first article inspection.<img src="https://img.pcbx.com/dev/file/image/article/20260716/62460c765a2a4fe6a059ee05fb131e63.jpg" alt="PCB Assembly Design Errors-PCBX" data-href="" style="width: 100%;"/><h3>Thermal Management Left as an Afterthought</h3>Thermal design is usually considered a post-layout problem instead of beginning design where thermal design can be a constraint. Components may fail prematurely in the field if proper copper pour, thermal vias, or separation from heat-sensitive components are not included. This point is particularly important for power-dense applications like motor drives or power converters, because heat on or close to switching elements can damage capacitors, ICs, etc., in the future. More often than not, it is easier to consider the thermal aspects at layout phase than to add a heatsink at a later stage.<h3>Signal Integrity Planning at High speed</h3>As the clock rates and data rates continue to rise, cosmetic decisions for trace routes become electrically significant. Unmatched trace lengths on differential pairs, routing high-speed signals over split ground planes or placement of vias inappropriately along a critical signal path can cause reflections, crosstalk or timing skew. These problems are frequently not discovered until a board is really loaded and operating, and thus difficult to correlate to some layout decision, and costly to backtrack to. Fixing routing and return-path continuity issues after a layout has been completed requires a lot of engineering time and is a source of headaches during certain classes.Routing and return-path continuity issues can be a headache time sink that can take weeks of engineering time if not planned for upfront.<h3>Panelization and Fiducial Oversights</h3>Late decision of panelization can lead to additional conflicts at the assembly line. A board without proper fiducial markers, or if the spacing between the individual units on a board is inconsistent, will require manual adjustments which will slow throughput and introduce placement variability. Panelization strategy and assembly line planning should not be done as a formality after tooling has been ordered, but rather should be coordinated when the assembly line is first designed.<h3>Silkscreen and Test Point Neglect</h3>As you approach tape-out, it's easy to forget about the silkscreen legends and test point placement, but they come back to bite you in the rear down the road. Unspecified or incorrect polarity marks on parts such as electrolytic capacitors and diodes can increase chances of incorrect component polarity. Boards with inaccessible test points are also slower and less predictable when it comes to in-circuit testing and functional debugging, especially during the initial production volumes, where every second counts to get the product to market.<img src="https://img.pcbx.com/dev/file/image/article/20260716/9165d708791a421398d127bb5aba34bc.jpg" alt="PCB Layout Best Practices-PCBX" data-href="" style="width: 100%;"/><h3>Overlooking Manufacturer-Specific Design Rules</h3>The generic design rule checks (DRC) in the EDA tools are useful for detecting obvious problems (e.g., width of traces, unconnected nets, etc.) but don't consider the specific usability and tolerances of the fabricator that is going to build the board. The minimum trace and space requirements (aspect ratios), as well as copper weight limits, differ from one manufacturing house to another and a design that passed through a generic DRC could still need expensive rework on one particular production line. This gap is closed when the design files are shared with the fabricator before finalizing the design layout, rather than after it is finalized.What is common to all of these pitfalls is that manufacturability and reliability issues are much easier to overcome in the design phase than once fabrication or assembly starts. Placing a habit in the early and repeated review of footprints, thermal risks, signal integrity problems, and DFM conflicts before Gerbers are sent out, tends to result in boards that pass first article inspection without a lot of surprises and get to volume faster.

Avoid costly PCB design mistakes in footprints, spacing, thermal management, and DFM before production.

How to Avoid Pitfalls in PCB Design

How to Reduce Ground Bounce in PCB Assembly

Among all the signal integrity issues of high-speed PCBA production, ground bounce, or simultaneous switching noise (SSN), is one of the most challenging. It's a transient voltage change on ground planes that occurs when a large number of IC input/output pins change logic at once. Ground bounce can cause false logic levels, drift in logic timing, EMI radiation, and sometimes lead to complete system failures – particularly in multi-layer high-frequency boards used in communication, industrial control and consumer electronics applications – where parasitic inductance of ground traces, vias and component leads cause ground bounce. This article combines layout optimization, component assembly specifications, circuit design modifications, manufacturing standards and provides actionable tips for the suppression of ground bounce during PCB manufacturing with a well-balanced technical data and manufacturing guidance.<h3>Root Mechanism of Ground Bounce</h3>The fundamental equation that describes the ground bounce voltage is V = L × di/dt. There is parasitic inductance L present on all conductive paths of PCB. If several outputs switch simultaneously, the transient current flow di/dt produces transient voltages on the ground loop inductance which raises the ground voltage above and below zero volts at the point in question. There are three main reasons behind the severity of the bounces: high loop inductance of the poorly routed power-ground networks; fast slew rates of the devices; and large number of synchronized switching pins. Ground planes are often divided in assembly and long traces for capacitors are used creating even more inductance, and even poorer noise amplitude.<img src="https://img.pcbx.com/dev/file/image/article/20260702/2575410948ba4a0c9f482ed8f99b6380.jpg" alt="Root Mechanism of Ground Bounce-PCBX" data-href="" style="width: 100%;"/><h3>Core Practical Solutions to Mitigate Ground Bounce</h3>Build Low-Impedance Power and Ground Plane StructuresThe first and easiest cure for ground bounce is to reduce loop inductance. In order to ensure multi-layer PCBs have continuous, non-segmented solid ground planes to provide the shortest, lowest-impedance return paths for switching current, the ground planes must be continuous and not sectioned with traces. The ground layers should be placed next to the power layers, and the compact dielectric design creates distributed planar capacitance to ensure a quick transient voltage stabilization.All power and ground is routed short and wide for single or 2-layer boards when no full planes are present, to reduce the trace inductance. Stitch dense vias across ground pours to tie together ground potential and prevent ground islands. Multipin power/ground connections in the package of high-speed ICs provide additional benefit by dividing transient current load and minimize single path inductive noise.Standardize Decoupling Capacitor Placement and AssemblyDecoupling capacitors are the most cost-sensitive anti-bounce component, which acts as a local energy reservoir to take up the current surge caused during switching without contaminating the main ground loop. The small high frequency ceramic capacitors 0201/0402 (0.01μF–0.1μF) should be placed within 1mm of the VCC and GND pins of the IC with no long routing traces. Many parallel grounding vias under each Capacitor pad reduces via inductance and enhances high frequency response.A mixed-value capacitor stack spans over the entire frequency range of noise: small low-value ceramic capacitors are used for handling very fast transients, larger low-ESR MLCCs for voltage droop in the mid-frequency range and bulk electrolytic capacitors for voltage stabilisation in the low-frequency range. If there are layout constraints that do not allow near pin placement, capacitors can be attached to the opposite layer of the board under the targeted ICs to reduce current loop areas. Cold solder joints are eliminated with strict assembly inspection, and will compromise grounding impedance and decoupling performance.Separate Analog and Digital Ground for Mixed-Signal BoardsMixed-signal PCBs include noise-prone digital switching circuits with sensitive analog sensors and amplifiers, where ground bounce is able to couple in to weak analog signals, causing measurement distortion. The standardized assembly layout divides the board into separate digital ground (DGND) and analog ground (AGND) areas where all high-speed switching devices and digital ICs are kept in the DGND areas.The two ground domains are tied together only at a single point at the main power input with a zero-ohm resistor or ferrite bead to prevent high frequency ground bounce from sneeping into analog circuits. Shared high inductance return paths are eliminated and analog module reference voltage remains clean with isolated grounding.Restrict Simultaneous Switching and Control Signal Slew RateThe largest ground bounce peaks occur in mass synchronized I/O switching, which means that hardware and firmware changes help to disperse current surges. The rate of rise or fall of the output signal can be slowed by placing 22–100Ω series damping resistors on the IC output pins, which limits the di/dt. Choose ICs that have adjustable drive strength for their outputs and determine the minimum output drive current required for timing purposes. Firmware optimisation delays switching between multiple channel data buses to prevent simultaneous switching of all data bus pins in bulk.Another aspect of component packaging that affects bounce is the type of package used: BGA and CSP packages have short lead inductance, which reduces the noise sources at the assembly stage.<img src="https://img.pcbx.com/dev/file/image/article/20260702/cd1e48723fb7443dbcb4c7ae6c3fdad5.jpg" alt="Restrict Simultaneous Switching and Control Signal Slew Rate-PCBX" data-href="" style="width: 100%;"/>Optimize Via Layout and Assembly Process ControlsA parasitic inductance is formed by the Vias and a sparse, long Via causes major instability and loss in ground performance. Use arrays of short through-via connections between the grounds of the components or other parts and the ground plane near high-speed switching chips to spread transient current over dozens of parallel conductive paths. Do not use a deep blind or buried via for grounding, as the longer the barrel the more it will increase in inductance.Quality checks after the assembly are a complement: automated optical inspection programs check the full soldering of capacitors and via connectivity, and oscilloscope tests record the ground plane voltage bounces to determine bounce amplitude. Repeated changes of capacitors and capacitor positions reduce noise to acceptable design limits.The process of ground bounce mitigation requires a multi-layer approach of PCB design and manufacturing of the assembly where the emphasis is to minimize loop inductance, maintain a stable ground reference potential and distribute peak switching currents. Together, continuous ground planes, carefully positioned multi-value decoupling capacitors, isolated analog-digital grounding, slew rate control and dense grounding vias work together to effectively suppress ground bounce noise. The rigorous SMD assembly quality control also ensures signal integrity of high-speed electronic hardware.If PCB designers and manufacturers are looking for reliable, high performance PCBA services with optimized signal integrity workflows that will allow them to avoid ground bounce, crosstalk and EMI problems for all high frequency board projects, PCBX delivers customized layout consultation, precision component assembly and full signal integrity testing to eliminate ground bounce, crosstalk and EMI issues for all high-frequency board projects.

Learn practical PCB assembly methods to eliminate ground bounce & SSN, optimize signal integrity for high-speed electronics.

The first engineering decision in every embedded PCB design is whether it uses a Microcontroller Unit (MCU) or a Field-Programmable Gate Array (FPGA) as the processing core. The architecture and working mechanisms of both power embedded electronic systems are quite different, and their PCB layout specifications are fundamentally different. The choice of this critical decision directly affects the operational performance, power efficiency, overall budget, development time, and future upgrade possibilities of a project. Understanding both the unique strengths and constraints of MCUs and FPGAs is crucial for PCB designers to prevent unneeded design duplication or inadequate system performance. This article provides pure original, PCB oriented insights to guide engineers for the right processor selection for different embedded design scenarios.<h3>Fundamental Architectural Differences</h3>The fundamental difference between MCUs and FPGAs is their operating logic, which is what all the other PCB design rules are based on. The term MCU is used to refer to a fully integrated, fixed-function chip with a CPU core, memory and standard peripherals. It runs the programmed instructions sequentially, line by line, to finish control tasks, to collect data and also to perform slow communication. The hardware design is fixed and only firmware updates allow for functions to be changed.Unlike ASICs, FPGAs have a blank-slate hardware architecture of programmable logic arrays and reconfigurable interconnects and no fixed processing cores or peripherals. Dedicated hardware circuits are customized using hardware description languages (HDL) allowing for the fact that multiple independent logic tasks can be executed in parallel. In addition to this configurability, this hardware level differentiates FPGA from software limited MCUs and enables ultra-low latency and high throughput processing scenarios.<img src="https://img.pcbx.com/dev/file/image/article/20260630/e7a9dd1feda14d059bcbe9e829001fda.jpg" alt="Compare FPGA and MCU-PCBX" data-href="" style="width: 100%;"/><h3>PCB Design and Performance Tradeoffs</h3>PCB designs based on MCU are extremely simple and functional. MCUs are packaged in a small size with a dense pin distribution and with highly integrated on-chip functions they need only a few auxiliary components. In most low to medium speed MCU apps, only 2-4 layer PCBs are required, routing is loose, there is no required high speed impedance matching, and high manufacturing yield is desired. In addition, MCUs provide multi-level low power sleep states which are suitable for battery operated portable applications and low energy terminals for IoT applications.There are much more demanding PCB design requirements for FPGAs. High-performance models use packages that include many pins, which are split into multiple I/O power domains, and these packages must be powered by multiple power supply circuits that must be designed with power sequencing. For high-speed signals like differential signals and high bandwidth memory, the requirements for impedance control, trace length matching and crosstalk suppression are very tight and typically call for 6-12 precise layer PCBs. FPGAs offer significantly greater parallel processing power and nanosecond real-time response, but have more complex hardware designs, which results in higher power usage, increased heat generation and greater thermal layout planning requirements.<h3>Cost and Development Cycle Evaluation</h3>An important strength of MCU-based solutions is the ability to control cost and to speed up iteration. From cheap to mainstream low-cost designs, MCUs have low chip pricing and fewer peripheral matching requirements to significantly reduce BOM and PCB costs. The MCU development has a low learning barrier because of the high-level development frameworks, open-source libraries and extensive community technical support. It enables fast prototype verification and cost-effective product iteration to meet the market's requirements for short time-to-market and mass production.On the other hand, FPGA-based solutions require greater initial development and hardware costs. The FPGA chips themselves are also more expensive, and use of FPGA involves extra configuration circuits, specially-designed power management circuits, and professional simulation software, all of which will increase project costs. Compared with ASIC, FPGA also has high technical requirements: Digital circuit knowledge, timing constraint debugging skills, etc., which leads to a longer development time. Despite this, its singular ability to reconfigure the field makes it possible to change the internal hardware logic and to increase product functions after the production of the PCB, ensuring unparalleled scalability and adaptability for iterations and custom-made embedded products.<h3>Target Application Scenarios</h3>MCUs are well suited for cost-sensitive low power and simple control applications such as smart home appliances, wearable devices, auxiliary control devices in automotive electronics and traditional sensor data acquisition systems. The requirement in these scenarios is to optimize stability, energy consumption, and fast mass production, and that is where sequential MCU processing can easily satisfy the demands of operation.<img src="https://img.pcbx.com/dev/file/image/article/20260630/000ec0280e134f57ba4b97d1a610f773.jpg" alt="PCB Design Tradeoffs-PCBX" data-href="" style="width: 100%;"/>FPGAs are ideal for high performance, time-critical applications such as real-time digital signal processing, high-definition video processing, precision industrial motion control, and high-speed communication systems. They are irreplaceable for the design of high-end embedded hardware products, with their parallel computing and low-latency processing, to eliminate performance bottlenecks of the sequential MCU operation.However, for high-end systems, a hybrid MCU+FPGA solution has become the mainstream approach. The MCU takes care of system scheduling, human-computer interaction and low-speed control, and the FPGA handles high-speed data processing, optimizing for cost, power consumption and system performance.In conclusion, MCUs and FPGAs are used to design in two directions that are differentiated in embedded PCB. The simplicity, cost efficient and low power stability make MCUs ideal for traditional control, consumer electronics and low power IoT devices. FPGA systems are preferred for high-performance signal processing, communication and industrial precision control applications because they are dedicated to high-speed parallel computing, have very low latency, and offer hardware reconfigurability. For more complex scenario, the hybrid MCU-FPGA architecture is an ideal solution for balancing cost, power consumption and performance. When superior reliability, accuracy at the highest level and manufacturing capability for all embedded processor solutions is required, PCBX provides professional one-stop support for PCB fabrication, layout optimization and mass production.

Compare FPGA and MCU core differences, PCB layout tradeoffs & use cases to select the best processor for your embedded hardware design.d

How to Choose Between FPGA and Microcontroller for PCB Design

EMI vs EMS vs EMC: Electromagnetic Compatibility

Electronic and electrical devices are abundant today in all modern societies, from mobile devices used in everyday life, such as mobile phones, tablets, and household appliances, to industrial automation systems, precision medical devices and intelligent automotive equipment. Continuous use of electronic devices unavoidably produces and generates electromagnetic energy. This diffuse electromagnetic energy, if not controlled and suppressed in an effective way, will cause interference among the neighboring equipments that will result in the distortion of the signal, instability of operation and possible abrupt malfunction of the equipments. The emission, anti-interference and compatibility properties of electronic equipment in the public electromagnetic environment are systematically defined by three basic electromagnetic concepts: EMI, EMS and EMC. This article talks about their professional definitions, basic classifications, inner logical relationships and practical application value in electronic engineering.<h3>EMC: The Overall Standard of Electromagnetic Compatibility</h3>EMC (Electromagnetic Compatibility): It is the ability of electronic equipment to work properly in complex electromagnetic environment. It means that devices need to be able to keep their electromagnetic noise within tolerable limits to prevent interference to other devices and to ensure reliable performance in the presence of outside noise. In other words, EMC establishes the basic guidelines for safe and reliable coexistence of electronic devices.It is a complete and systematic technical performance indicator, and consists of two essential parts: electromagnetic interference emission indicator and electromagnetic anti-interference immunity indicator, which are consistent with the definition of EMI and EMS performance indicators respectively. Both of the two dimensions cannot be neglected in product design, research and testing. The superior EMC compliance is now an essential requirement for commercial electronic products worldwide. It can ensure the stable operation of industry control and command system, the safety of precision medical and automotive electronic equipment, and the accurate and continuous transmission of various civil and industrial wireless communication systems.<img src="https://img.pcbx.com/dev/file/image/article/20260625/13cfd01b34aa49a991cf55fe157d2e98.jpg" alt="EMC: The Overall Standard of Electromagnetic Compatibility-PCBX" data-href="" style="width: 100%;"/><h3>EMI: Active Electromagnetic Interference Emission</h3>A redundant electromagnetic noise produced and emitted from electronic equipment during normal operation and which can interfere with the service of other electronic and electrical equipment is known as EMI (Electromagnetic Interference). It is essentially the active interference output of the electronic products, and is an important factor that affects the overall electromagnetic environment quality of the surrounding area, and must be strictly controlled in the development of electronic products.There are two types of EMI—conducted and radiated interference. Conducted EMI is transmitted along the power lines and signal cables, with the primary sources being switching power supplies and motor drives, and is mainly seen at low and medium frequencies. Radiated EMI travels in the air, and is more significant in high frequency noise from wireless modules and high speed circuits.In everyday life and industrial applications, it is easy to see that there are numerous EMI disturbance phenomena, such as the static picture on TV, there is static noise when high-power microwaves are working, the Bluetooth audio signal is unstable, and the start-up power surge of high-power appliances causes the precision sensors to drift or have interrupted connections. These are common side-effects of unregulated and overpowering EMI emissions from poorly designed electronic equipment.<h3>EMS: Passive Electromagnetic Immunity</h3>EMS (Electromagnetic Susceptibility) is the resistance of the device to the outside electric and magnetic interference and normal operation. EMS is passive defense capability, which is the ability of a device to adapt to the environment, unlike active emission like that of EMI.Likewise, there are two types of immunity in EMS: conducted immunity and radiated immunity. When it comes to equipment and line-borne noise like voltage fluctuations and electrical pulses, conducted immunity is what you need. Radiated immunity is protection from external electromagnetic radiation from devices such as radar and radio transmitters and surrounding wireless devices.High precision and high reliability equipment has a particular emphasis on their stable and high performance in EMS. In operating rooms, where electromagnetic radiation is present, the precision instruments of medicine for clinical diagnosis and surgical treatment need strong electromagnetic immunity to prevent operational errors and guarantee the safety of medicine. At the same time, as the backbone of present-day smart vehicles, electronic control units (ECU) in the vehicle also demand excellent EMS performance to withstand the complex electromagnetic noise generated inside the vehicle and ensure driving safety and stability.<h3>Core Relationship Between EMC, EMI and EMS</h3>There is very clear logical relation among the three terms, EMC is the overall evaluation standard, and EMI and EMS are two important sub-parameters of EMC. If only one of EMI emission is low or EMS immunity is low, it cannot be qualified.Equipment should not impede others – EMI – Focus on restraint EMS is about robustness, that is, equipment should be hard to interfere with by others. Finally, a harmonious electromagnetic coexistence is achieved by multi-device systems, achieving the balance between emission control and anti-interference capability, with the guarantee of EMC.<img src="https://img.pcbx.com/dev/file/image/article/20260625/3c4eb572dcbf445289a3238d7a7ece2e.jpg" alt="Practical Importance of EMC Testing-PCBX" data-href="" style="width: 100%;"/><h3>Practical Importance of EMC Testing</h3>As high frequency circuits and wireless communication technology are rapidly developed and popularized, the electromagnetic environment in daily life and industrial environment is becoming dense and complicated. For EMI emission, signal instability will directly lead to intermittent failure of the equipment, or data error in industrial production process, or even endanger the safety of high precision medical and auto and aerospace industries; unqualified EMI immunity will lead to signal instability and intermittent failure of the equipment. Hence, the standardized detection of EMI and immunity testing of EMS has become indispensable for product development and market access certification. The optimal design of the circuit shielding, scientific grounding design, and internal noise suppression structures can enhance the overall EMC performance and long-term service reliability of electronic products.In summary, EMI is the electromagnetic interference that an electronic equipment emits during operation; EMS is the anti-interference ability that an electronic equipment has against external electromagnetic interference; and EMC is the entirety formed by the combination of qualified EMI and EMS indicators. In the modern electronic engineering design, testing and production, the three concepts are highly linked and cannot be separated from each other. Understanding the concept of EMI, EMS & EMC is important for engineers to build more stable, safe and market compliant electronic products. With the continuous rapid development of intelligent terminals and wireless technology, professional EMC technology will continue to be an important guarantee for the normal operation of all kinds of electronic systems in complex electromagnetic environment.

Learn EMI, EMS & EMC definitions, differences and testing basics for electronic engineers in this EMC compatibility guide.

EMI vs EMS vs EMC: Understanding Electromagnetic Compatibility

Ringing is a typical signal integrity issue in the design of a PCB, which refers to the unintended voltage oscillation that occurs when a digital signal transitions from low to high (or high to low). Often used as part of the high-speed clock lines, data traces, switching circuits. A high level of ringing may lead to incorrect logic triggering, increase electromagnetic interference (EMI), damage sensitive equipment and result in system failures. With the development of electronic products to higher speed and higher density, the control of ringing has become an important task for a reliable development of PCB. This article discusses the effects of ringing and provides practical and effective solutions, including circuit design, circuit layout, power management and material selection.<h3>Fundamental Causes of PCB Ringing</h3>The primary sources of ringing are reflection of the signal and parasitic resonance in the transmission lines. There is an inherent inductance and capacitance associated with a PCB trace. If the impedance of the signal source, trace and load are not equal, the signals reflect at the points where they are discontinuous. When incident wave and reflected wave are added together, voltage fluctuations come and go. There are many design defects that exacerbate this situation: excessive signal edges speed up the edges that contain rich high-frequency harmonics; long traces add more parasitic parameters; improper bends cause changes in the impedance; redundant stubs and broken ground planes also change the impedance and increase the chances of oscillation.<img src="https://img.pcbx.com/dev/file/image/article/20260611/602d0462a1384027bbee81c6cfe83d60.jpg" alt="How to Reduce Ringing in PCB Design-PCBX" data-href="" style="width: 100%;"/><h3>Comprehensive Strategies to Minimize Ringing</h3>Use Precise Impedance Matching and Signal TerminationThe simplest ways of reducing reflection and ringing are by impedance matching and terminating. There are two major termination methods that are applicable to various situations. The termination circuit for a series termination is a 22 Ω to 100 Ω resistor directly across the output pin of the driving chip. It is a suitable option for short and medium trace lengths, matches source and trace impedances, and is commonly employed with clock signals and digital I/O lines. Parallel termination is recommended for long single-ended traces. Add a pull-up or pull-down resistor in close proximity to the receiver whose resistance is equal to that of the trace characteristic impedance, which is normally 50 Ω, 75 Ω, or 100 Ω. If differential pairs such as LVDS are used, use a separate differential termination resistor near the receiving end. Be sure to keep all termination resistors close to chip pins, too much stub will add new parasitics and affect performance.Moderately Adjust Signal Slew RateAnother effective signal slew rate adjustment method is available. High frequency ringing can be easily excited by ultra fast rising and falling edges. The non-time-critical signals can have its signal edges smoothed appropriately. A 10pF to 100pF series ceramic capacitor is suitable for filtering high-frequency signals and smoothing out sharp edges on signal lines. The slew rate modes are programmable in most modern MCUs, FPGAs and logic chips. Slow slew rate can be used to reduce ringing without adding any additional components. But it is necessary to have moderate edge slowing. Too long of a transition time will result in timing errors and it will impact normal data communication.Implement PCB Layout and Routing RulesStandardized layout and routing eliminate source ring. The first thing to do is to minimize the length of high-speed signal and clock paths and keep like components together. Secondly, prevent right angle bends and avoid unnecessary stubs on high speed paths. Instead use 45 degree or arc bends and keep trace width constant to keep impedance constant. Third, keep what is considered critical traces above a complete ground plane. A good reference plane not only optimises the signal return path but also reduces the parasitic inductance, crosstalk and keeps oscillations in check. Avoid putting high-speed traces near noise sources like power switches and inductors.Minimize Grounding and Power Decoupling DesignEfficient distribution and grounding are also key factors. Create a decoupling network for all chips. Use the same polarity 0.1 μF high frequency capacitors as close to the power and ground pins as possible to suppress transient currents. Use small high-frequency capacitors and large bulk capacitors on large integrated circuits to deal with noise at various frequencies. Use thick copper traces/groups for ground and power lines instead of thin traces to reduce line impedance. In high-speed areas, beware of split ground planes since they will introduce longer return paths and make ringings worse. A simple RL snubber provides additional damping of parasitic resonance for switching circuits.Choose the Right Components and PCB MaterialsThere is also a significant influence on the ringing performance of the composition of the components. If the device is performing as designed, use devices with moderate switching speeds rather than devices with very high switching speeds. Slower switching components will naturally have less high frequency harmonics and weaker ring. Use low jitter models for oscillators and clock sources for minimising initial signal distortion.The quality of the high frequency signal transmissions depends on the PCB substrate materials. If you use high-speed, high-frequency designs, choose substrates with low dielectric-loss and low dispersion. High dielectric loss materials will cause distortion of signals at high frequencies, and worsen oscillation. In parallel, a reasonable design of the PCB stack-up: stack high-speed signal layer adjacent to ground layer to realize the accurate control of the impedance, so as to avoid mutual influence between high-speed signal layer and ground layer. Do not stack multiple high speed signal layers without ground isolation.<img src="https://img.pcbx.com/dev/file/image/article/20260611/8f643104d2344b138f3bf3995aba981c.jpg" alt="Reasonable Component and PCB Material Selection-PCBX" data-href="" style="width: 100%;"/>Leverage Simulation and Pre-TestingPrior to mass production, take advantage of professional signal integrity simulation tools to test the amplitude of signal reflection and ringing, and trace impedance. Run various termination schemes, routing distances and component parameters to determine possible problems and design optimization before schematic and layout is finalized. Following prototype fabrication, measure real signal waveforms on oscilloscopes, confirm the improvement effect, and adjust component parameters and routing as needed based on the results of the oscilloscope test. Simulations and physical testing complement each other in the process of more effective, targeted ring control.The choice of components and pcb can not be ignored. Use components that have a suitable switching speed rather than simply being after the fastest speed. Low jitter clock sources also contribute to clean original signals. To reduce the distortion of signals, choose low-dielectric-loss PCB substrates for high speed and high frequency applications. In the meantime, come up with a scientific "stack-up" by positioning high-speed signal layers adjacent to ground layers for stable impedance, and noise isolation.Through the above comprehensive applications, designers can achieve significant reduction of signal ring, enhancement of signal quality, reduction of EMI risk, and ensuring long-term stable operation of electronic products. With continuously changing high-speed circuits, now it has become a fundamental skill for PCB engineers to learn about how to suppress ringing. With your trust in reliable, high-performance PCB design and signal integrity optimization services, PCBX is here to provide you with custom and top-notch solutions for your varying design needs.

Explore effective solutions to minimize PCB ringing via impedance matching, routing optimization, component selection and pre-production testing.

How to Reduce Ringing in PCB Design?

What is Chip-on-Board (COB) in PCB Design?

Compared to the worldwide trend of miniaturisation, light weight and cost reduction, traditional prepackaged SMD chips are difficult to meet the requirements of compact layout and high heat dissipation of modern LED, wearable, automotive and medical electronics. Chip-on-Board (COB) is a type of electronics packaging that is considered to be in the intermediate stage of packaging, Level 1.5, and has become a mainstream specialized PCB assembly solution. Compared to conventional components that are packaged in plastic or ceramic packages, COB eliminates the need for individual chip packaging, thereby greatly reducing signal path length, maximizing thermal conductivity and conserving board space.<h3>What is Chip-on-Board（COB）?</h3>COB is a more advanced packaging technique which uses cured epoxy to completely encapsulate the chips and electrical connections to make stable electrical contact and to provide physical and chemical protection through fine bonding wires or flip-chip solder bumps, as well as pre-designed PCB bonding pads. COB reduces the amount of raw material waste as lead frames and separate packaging housings are eliminated, and can also reduce the total cost to about one-third that of the conventional packaged chip in mass production. There are two popular design formats for mature designs in use today:Wire-bonding COB: The most common, a mature solution. The inner electrodes of the chips are then bonded to larger bonding pads on the PCB using ultra-fine gold or aluminum micro-wires via ultrasonic bonding, with bare dies glued to specific areas of the PCB. It is essential for PCB designers to carefully select and configure the size and pitch of the pads in accordance with the parameters in the die datasheet, otherwise it will easily cause a broken wire in the production process. All sensitive structures are protected against dust, moisture and mechanical damage by post-bonding epoxy glob-top.<img src="https://img.pcbx.com/dev/file/image/article/20260604/f443f36d447b4e6a937758426ee641c1.jpg" alt="What is Chip-on-Board-PCBX" data-href="" style="width: 100%;"/>Flip-Chip on Board (FCOB): Designed for high frequency and high density circuits. These are upside down, and have prefabricated solder bumps on the contact surfaces. The relevant PCB pads are treated with flux, and flipped chips are reflowed with the other passive components. Its PCB pad design is designed to conform to the modified BGA specification, specifying the bump dimension, which makes it possible to obtain ultra-short signal paths to minimize loss of high-frequency signals.<h3>Seven-Step COB Manufacturing & Adhesive Selection</h3>COB production is a set of seven standardized steps that meet the requirement of PCB design:Substrate preparation: Thoroughly clean the PCB bonding regions and use a special surface plating on the designated regions to prevent cross-contamination in the assembly process.Die attach: Automated pick and place tool is used to dispense selected adhesive and precisely position bare dies, with PCB leaving clear area for any overflow adhesive.Pre-inspection: Ensure that the accuracy of the die is correct to avoid misplacing it.Electrical bonding: Full bonding or full flip-chip reflow to ensure the stability of circuit connections.Encapsulation: Over-coat chips and links with epoxy cured by UV or heat to create protective glob-top chips and links.Multi-aspect testing: Run electrical continuity, visual inspection and temperature cycling tests to screen defective products.Final assembly: Integrate qualified COB PCBs into finished electronic products.There are two common adhesives used to attach the die: Silver conductive glue requires high temperature curing and is applicable to high power MCPCB that has high thermal dissipation requirements; Anaerobic glue is a type of glue that cures under anaerobic (airless) conditions, which are suitable for low power circuits that do not require thermal dissipation.<h3>Important PCB Design Concepts for COB</h3>There are a number of fundamental rules for COB reliability: First, the COB bonding pads are divided into separate blocks with larger copper sizes corresponding to the chip. Second, place dense thermal vias under high power dies to speed heat dissipation and prevent heat sensitive components from hot spots. Third, reduce the length of high-speed signal traces and include ground guard signal traces between analog and digital circuits to minimize the crosstalk and EMI effect. Fourth, provide sufficient air space between COB regions to provide for overflow epoxy during encapsulation. Last but not least, cover the bonding pads with hard gold plating and the rest of the circuit with cost-effective OSP/HASL for performance and cost.<h3>Advantages and the Limitations of COB Technology</h3>BenefitsCOB consumes 30% to 60% less board area than traditional packaged chips in order to achieve the thinner device. Direct contact of the die to the substrate yields highest heat transfer and is dominant for high power LED modules. In mass production, the separation of the packaging is a significant cost reduction. A shorter connecting path reduces parasitic impedance for high-frequency electrical performance and full epoxy encapsulation provides protection from moisture, vibration and chemical erosion.DrawbacksThe cost of small batch prototyping increases with specialized bonding equipment and design knowledge. After epoxying these faulty dies can't be replaced one by one – typically, a whole PCB has to be replaced, increasing the maintenance expense. Even so, passive components such as resistors continue to use the traditional SMT soldering, which restricts the whole board COB application.<img src="https://img.pcbx.com/dev/file/image/article/20260604/32585aea8e61473db90b6e5adefc764d.jpg" alt="" data-href="" style="width: 100%;"/><h3>Core Application Fields</h3>The unique strengths of COB-equipped PCBs have resulted in their wide-spread market coverage in various industry segments. High power LED lighting is the biggest application scenario, and in this case, COB LED is also widely used in aluminum core MCPCB's commercial downlights, stage lighting and automotive headlight modules. COB is used in miniaturization of wearable electronics such as hearing aids and smartwatch control boards for reducing the thickness of the components inside the devices. COB's excellent anti-vibration and broad temperature flexibility are utilized in automotive electronics applications such as ambient light controllers in the car and tire pressure monitoring systems. COB PCB is also used in portable medical testing instruments and compact industrial signal transmitters in order to comply with the industry miniaturization and high reliability requirements.COB is continually developing new products, technologies, and innovations to produce more fine-pitch flip-chip designs and optimized encapsulation solutions. While traditional SMD packaging still plays a dominant role in the majority of low-density circuits, COB is unmatched for high-power, miniaturized and high reliability electronic products in lighting, automotive, medical and new IoT fields. Electronic developers who need professional COB PCB layout validations, COB production and manufacturing feasibility consultant, PCBX delivers one-stop technical support covering PCB layout verification, substrate manufacturing and COB assembly feasibility assessment, helping electronic developers turn COB design concepts into stable mass-produced finished boards efficiently.

Learn what Chip-on-Board (COB) is in PCB design, covering types, manufacturing process, benefits and industrial applications for compact electronic circuit design.

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