{"id":31591,"date":"2026-07-21T10:38:17","date_gmt":"2026-07-21T02:38:17","guid":{"rendered":"https:\/\/www.bestpcbs.com\/blog\/?p=31591"},"modified":"2026-07-21T11:00:10","modified_gmt":"2026-07-21T03:00:10","slug":"parts-of-a-pcb","status":"publish","type":"post","link":"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/","title":{"rendered":"Parts of a PCB: Components, Functions, and Identification"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_84 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#What_Are_the_Main_Parts_of_a_PCB\" >What Are the Main Parts of a PCB?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#PCB_Board_Structure_Substrate_Copper_Pads_Vias_Solder_Mask_and_Silkscreen\" >PCB Board Structure: Substrate, Copper, Pads, Vias, Solder Mask, and Silkscreen<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#PCB_Components_List_with_Pictures_and_Functions\" >PCB Components List with Pictures and Functions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#How_Do_You_Identify_PCB_Components_on_a_Circuit_Board\" >How Do You Identify PCB Components on a Circuit Board?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#Surface-Mount_and_Through-Hole_Parts_What_Is_the_Difference\" >Surface-Mount and Through-Hole Parts: What Is the Difference?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#How_Do_PCB_Parts_Work_Together_in_Functional_Circuit_Sections\" >How Do PCB Parts Work Together in Functional Circuit Sections?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#How_Do_You_Build_a_PCB_Parts_List_from_the_Schematic_and_BOM\" >How Do You Build a PCB Parts List from the Schematic and BOM?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#What_Are_the_Basic_Steps_of_PCB_Design\" >What Are the Basic Steps of PCB Design?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/#Frequently_Asked_Questions_About_PCB_Parts\" >Frequently Asked Questions About PCB Parts<\/a><\/li><\/ul><\/nav><\/div>\n<div class=\"yzp-no-index\"><\/div>\n<p class=\"lead\">The <a href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/07\/parts-of-a-pcb\/\"><strong>parts of a PCB<\/strong><\/a> include two distinct groups: the physical features built into the bare board and the electronic devices assembled on its surface. Keeping these groups separate is the fastest way to understand a circuit board, identify unfamiliar parts, and communicate accurately with a PCB or PCBA supplier.<\/p>\n\n\n\n<p>A green board with chips and connectors is often called a PCB in everyday conversation. Technically, however, the bare board becomes a <a href=\"https:\/\/www.bestpcbs.com\/products\/pcba.htm\">printed circuit board assembly, or PCBA<\/a>, after components are soldered onto it. The distinction matters when you prepare fabrication files, purchase components, troubleshoot a failure, or request a quotation.<\/p>\n\n\n\n<p>This guide explains the board structure, common component names, functions, reference designators, mounting methods, specialized layouts, and the basic PCB design workflow. It is written for readers who need practical recognition skills rather than a component-theory textbook.<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/07\/parts-of-a-pcb-board.jpg\" alt=\"Parts of a PCB board diagram identifying the mounting holes, connectors, integrated circuit, resistor, capacitor, inductor, diode, LED, transistor, crystal oscillator, test point, and voltage regulator\"\/><\/figure>\n\n\n\n<div style=\"width: 100%; max-width: 600px; margin: 24px auto 34px;\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Are_the_Main_Parts_of_a_PCB\"><\/span>What Are the Main Parts of a PCB?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The phrase \u201cPCB parts\u201d can refer to the board itself or to the components installed on it. A complete explanation should include both.<\/p>\n\n\n\n<div class=\"wp-block-table\">\n<table>\n<thead>\n<tr>\n<th>Category<\/th>\n<th>Typical Parts<\/th>\n<th>Main Purpose<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>Bare-board structure<\/strong><\/td>\n<td>Core, prepreg, copper layers, solder mask, silkscreen, surface finish<\/td>\n<td>Provides mechanical support, electrical insulation, conductor patterns, protection, and readable markings.<\/td>\n<\/tr>\n<tr>\n<td><strong>Conductive features<\/strong><\/td>\n<td>Traces, planes, pads, vias, plated holes, copper pours, edge fingers<\/td>\n<td>Carry power and signals and create electrical connection points.<\/td>\n<\/tr>\n<tr>\n<td><strong>Electronic components<\/strong><\/td>\n<td>Resistors, capacitors, inductors, diodes, transistors, ICs, crystals, sensors<\/td>\n<td>Control current, store energy, process information, switch loads, and sense conditions.<\/td>\n<\/tr>\n<tr>\n<td><strong>Interconnection parts<\/strong><\/td>\n<td>Headers, sockets, USB ports, terminal blocks, board-to-board connectors<\/td>\n<td>Link the board to power sources, cables, modules, displays, motors, antennas, or other boards.<\/td>\n<\/tr>\n<tr>\n<td><strong>Mechanical and thermal parts<\/strong><\/td>\n<td>Mounting holes, standoffs, shields, clips, heatsinks, thermal pads<\/td>\n<td>Secure the assembly, control heat, and protect sensitive circuitry.<\/td>\n<\/tr>\n<tr>\n<td><strong>Test and service features<\/strong><\/td>\n<td>Test points, jumpers, programming headers, fiducials, probe pads<\/td>\n<td>Support assembly alignment, programming, measurement, inspection, and repair.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n<p>The board features create the electrical \u201croad system.\u201d The mounted components are the devices that use those roads to perform a function. A board without components can still be inspected electrically, but it cannot perform the intended product function until assembly is complete.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"PCB_Board_Structure_Substrate_Copper_Pads_Vias_Solder_Mask_and_Silkscreen\"><\/span>PCB Board Structure: Substrate, Copper, Pads, Vias, Solder Mask, and Silkscreen<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/07\/pcb-board-layers-structure.jpg\" alt=\"Exploded PCB board layers structure showing top silkscreen, solder mask, copper layers, prepreg, core, inner copper layers, and bottom silkscreen\"\/><\/figure>\n\n\n\n<div style=\"width: 100%; max-width: 600px; margin: 24px auto 34px;\"><\/div>\n\n\n\n<p>A PCB is a laminated stack of insulating and conductive materials. The exact structure changes with the layer count, impedance requirement, voltage, heat load, flexibility, and manufacturing process, but the principal features remain recognizable.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Substrate, Core, and Prepreg<\/h3>\n\n\n\n<p>The substrate provides rigidity and electrical insulation. FR-4 glass-reinforced epoxy is common in industrial and consumer electronics, while flexible circuits use polyimide and high-frequency boards may use low-loss laminates. In a multilayer board, cured core material and partially cured prepreg bond the copper layers into one structure.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Copper Traces and Planes<\/h3>\n\n\n\n<p>Traces are patterned copper conductors that route signals or current between pads. Planes and copper pours cover larger areas and commonly distribute ground, power, or heat. Their width, thickness, spacing, reference plane, and return path influence current capacity, impedance, noise, and temperature rise.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Pads, Plated Holes, and Vias<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>SMD pads<\/strong> receive the terminations of surface-mount devices.<\/li>\n\n\n\n<li><strong>Through-hole pads<\/strong> surround drilled holes used by leads, pins, or mechanical hardware.<\/li>\n\n\n\n<li><strong>Vias<\/strong> connect copper between layers. Common types include through vias, blind vias, buried vias, and laser-drilled microvias.<\/li>\n\n\n\n<li><strong>Via-in-pad structures<\/strong> place a via directly inside a component pad and usually require filling and planarization for reliable assembly.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Solder Mask, Silkscreen, and Surface Finish<\/h3>\n\n\n\n<p>Solder mask covers most exposed copper and helps control solder placement while protecting the circuit surface. Silkscreen adds reference designators, polarity marks, connector labels, revision codes, and other readable information. The surface finish protects uncovered copper pads and provides a solderable interface; common choices include HASL, ENIG, immersion silver, immersion tin, and ENEPIG.<\/p>\n\n\n\n<div class=\"tip\"><strong>Practical distinction:<\/strong> solder mask is not the electrical insulator between internal copper layers. Core and prepreg provide that dielectric function; solder mask is a thin outer protective coating.<\/div>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"PCB_Components_List_with_Pictures_and_Functions\"><\/span>PCB Components List with Pictures and Functions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/07\/common-pcb-components.jpg\" alt=\"Common PCB components with pictures including resistor, capacitor, inductor, diode, LED, transistor, integrated circuit, crystal, connector, switch, test point, and voltage regulator\"\/><\/figure>\n\n\n\n<div style=\"width: 100%; max-width: 600px; margin: 24px auto 34px;\"><\/div>\n\n\n\n<p>The table below is a practical PCB parts list. The reference letters are common conventions, but company libraries may use alternatives. The BOM and schematic remain the authoritative documents.<\/p>\n\n\n\n<div class=\"wp-block-table\">\n<table>\n<thead>\n<tr>\n<th>Component<\/th>\n<th>Common Designator<\/th>\n<th>Function<\/th>\n<th>Visual Identification Clues<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>Resistor<\/strong><\/td>\n<td>R<\/td>\n<td>Limits current, divides voltage, sets bias, provides pull-up or pull-down paths, and terminates signals.<\/td>\n<td>Small rectangular SMD body or axial through-hole body with color bands. Larger current-sense parts may be metallic and marked with low resistance values.<\/td>\n<\/tr>\n<tr>\n<td><strong>Capacitor<\/strong><\/td>\n<td>C<\/td>\n<td>Stores charge, filters noise, stabilizes power rails, couples AC signals, and supports timing networks.<\/td>\n<td>Small tan or dark SMD blocks, cylindrical aluminum electrolytics, molded tantalum packages, or film boxes. Polarized types have a polarity mark.<\/td>\n<\/tr>\n<tr>\n<td><strong>Inductor<\/strong><\/td>\n<td>L<\/td>\n<td>Stores energy in a magnetic field and filters current in converters, RF networks, and power inputs.<\/td>\n<td>Coil, ferrite bead, molded block, or shielded square package. Power inductors are often among the tallest SMD parts.<\/td>\n<\/tr>\n<tr>\n<td><strong>Diode<\/strong><\/td>\n<td>D<\/td>\n<td>Controls current direction, rectifies AC, clamps voltage, protects against reverse polarity, or suppresses transients.<\/td>\n<td>Two-terminal package with a stripe or line indicating the cathode. TVS diodes may resemble small IC packages.<\/td>\n<\/tr>\n<tr>\n<td><strong>LED<\/strong><\/td>\n<td>LED or D<\/td>\n<td>Emits light for status indication, illumination, optical sensing, or communication.<\/td>\n<td>Clear or colored through-hole lens, white SMD package, or compact multicolor package. Polarity must be observed.<\/td>\n<\/tr>\n<tr>\n<td><strong>Transistor or MOSFET<\/strong><\/td>\n<td>Q<\/td>\n<td>Switches or amplifies electrical signals and controls motors, LEDs, relays, converters, and processor power rails.<\/td>\n<td>Usually 3 or more terminals. Packages range from tiny SOT styles to large power packages with exposed thermal tabs.<\/td>\n<\/tr>\n<tr>\n<td><strong>Integrated circuit<\/strong><\/td>\n<td>U or IC<\/td>\n<td>Performs processing, memory, communication, sensing, regulation, amplification, or dedicated control functions.<\/td>\n<td>Black molded package with pins, gull-wing leads, bottom pads, or solder balls. A dot, notch, or chamfer identifies pin 1.<\/td>\n<\/tr>\n<tr>\n<td><strong>Crystal or oscillator<\/strong><\/td>\n<td>Y or X<\/td>\n<td>Provides a stable clock or reference frequency for processors, radios, interfaces, and timers.<\/td>\n<td>Metal can, ceramic SMD rectangle, or small oscillator module. Frequently located close to an MCU, FPGA, RF IC, or USB controller.<\/td>\n<\/tr>\n<tr>\n<td><strong>Transformer<\/strong><\/td>\n<td>T or TR<\/td>\n<td>Transfers energy or signals through magnetic coupling and may provide isolation or voltage conversion.<\/td>\n<td>Wound core or molded package. Ethernet magnetics may be integrated inside a connector.<\/td>\n<\/tr>\n<tr>\n<td><strong>Relay<\/strong><\/td>\n<td>K, RLY, or RL<\/td>\n<td>Uses an electrical control signal to open or close isolated mechanical contacts.<\/td>\n<td>Rectangular plastic housing, often with a printed coil voltage and contact rating. Requires more board area than semiconductor switches.<\/td>\n<\/tr>\n<tr>\n<td><strong>Fuse<\/strong><\/td>\n<td>F<\/td>\n<td>Opens the circuit when current exceeds a safe level.<\/td>\n<td>Glass cartridge, ceramic tube, polymer resettable fuse, or compact SMD body. A fuse should not be replaced with a higher rating without analysis.<\/td>\n<\/tr>\n<tr>\n<td><strong>Connector<\/strong><\/td>\n<td>J, P, or CN<\/td>\n<td>Connects power, signals, cables, modules, displays, sensors, or another circuit board.<\/td>\n<td>Header pins, sockets, edge connectors, USB ports, terminal blocks, FFC connectors, coaxial connectors, or board-to-board arrays.<\/td>\n<\/tr>\n<tr>\n<td><strong>Switch or button<\/strong><\/td>\n<td>SW or S<\/td>\n<td>Provides manual input, configuration, reset, mode selection, or power control.<\/td>\n<td>Tactile dome, slide switch, rocker, rotary encoder, DIP switch, or membrane contact area.<\/td>\n<\/tr>\n<tr>\n<td><strong>Sensor<\/strong><\/td>\n<td>U, S, TH, or application-specific<\/td>\n<td>Measures temperature, pressure, light, motion, magnetic field, current, humidity, sound, or other conditions.<\/td>\n<td>Appearance varies widely. Open ports, optical windows, exposed thermal pads, or MEMS packages may indicate the sensing function.<\/td>\n<\/tr>\n<tr>\n<td><strong>Test point<\/strong><\/td>\n<td>TP<\/td>\n<td>Provides a controlled location for probes, fixtures, programming, calibration, or production testing.<\/td>\n<td>Exposed round or rectangular pad, loop terminal, or plated post with a nearby TP label.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n<p>A visually similar package can contain very different internal functions. For example, a 6-pin SOT package may be a regulator, logic gate, sensor interface, or protection array. Package recognition narrows the possibilities; it does not prove the exact part number.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Do_You_Identify_PCB_Components_on_a_Circuit_Board\"><\/span>How Do You Identify PCB Components on a Circuit Board?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Reliable identification uses several clues together. A good process starts with non-destructive observation and moves toward documentation and measurement.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Read the reference designator.<\/strong> Labels such as <code>R12<\/code>, <code>C8<\/code>, <code>U3<\/code>, or <code>J1<\/code> reveal the component family and its unique location number.<\/li>\n\n\n\n<li><strong>Inspect the package.<\/strong> Count pins, note the body dimensions, and identify whether the part is axial, radial, leaded, leadless, BGA, QFN, SOIC, SOT, connector, or custom mechanical hardware.<\/li>\n\n\n\n<li><strong>Record the top marking.<\/strong> ICs often show a shortened code rather than the complete orderable part number. Photograph it under controlled lighting and search the marking together with the package and manufacturer logo.<\/li>\n\n\n\n<li><strong>Check polarity and orientation.<\/strong> Look for pin-1 dots, notches, diode bands, electrolytic capacitor stripes, LED cathode marks, and PCB silkscreen symbols.<\/li>\n\n\n\n<li><strong>Study the nearby circuit.<\/strong> A component beside an inductor and several ceramic capacitors may belong to a switching regulator. A crystal close to a microcontroller is probably part of its clock circuit.<\/li>\n\n\n\n<li><strong>Confirm with documentation.<\/strong> Use the schematic, BOM, assembly drawing, pick-and-place file, approved vendor list, or original product service manual.<\/li>\n\n\n\n<li><strong>Measure only when appropriate.<\/strong> Resistance, diode drop, capacitance, continuity, and rail voltage can provide evidence, but in-circuit measurements may be altered by parallel paths. De-energize the board before passive resistance or continuity checks.<\/li>\n<\/ol>\n\n\n\n<div class=\"note\"><strong>Important:<\/strong> do not power an unknown or visibly damaged board merely to identify a component. Check for shorts, contamination, reversed parts, burnt areas, and incorrect supply polarity first.<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Common Reference Designators<\/h3>\n\n\n\n<div class=\"wp-block-table\">\n<table>\n<thead>\n<tr>\n<th>Designator<\/th>\n<th>Usually Means<\/th>\n<th>Useful Identification Detail<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>R<\/td>\n<td>Resistor<\/td>\n<td>Value may be printed as a 3-digit, 4-digit, or EIA-96 code on larger SMD packages.<\/td>\n<\/tr>\n<tr>\n<td>C<\/td>\n<td>Capacitor<\/td>\n<td>Small ceramic capacitors are often unmarked; the BOM or measurement is usually required.<\/td>\n<\/tr>\n<tr>\n<td>L \/ FB<\/td>\n<td>Inductor \/ ferrite bead<\/td>\n<td>Ferrite beads may look like resistors but are used mainly for high-frequency noise suppression.<\/td>\n<\/tr>\n<tr>\n<td>D \/ LED<\/td>\n<td>Diode \/ light-emitting diode<\/td>\n<td>Orientation is critical. Confirm the board symbol and package mark.<\/td>\n<\/tr>\n<tr>\n<td>Q<\/td>\n<td>Transistor or MOSFET<\/td>\n<td>Nearby gate resistors, drivers, inductors, or loads help reveal the role.<\/td>\n<\/tr>\n<tr>\n<td>U \/ IC<\/td>\n<td>Integrated circuit<\/td>\n<td>Read the complete marking, logo, pin count, package, and pin-1 indicator.<\/td>\n<\/tr>\n<tr>\n<td>J \/ P \/ CN<\/td>\n<td>Connector<\/td>\n<td>The schematic net names usually explain whether it carries power, communication, or general I\/O.<\/td>\n<\/tr>\n<tr>\n<td>Y \/ X<\/td>\n<td>Crystal or oscillator<\/td>\n<td>Frequency may be printed directly on the package.<\/td>\n<\/tr>\n<tr>\n<td>F<\/td>\n<td>Fuse<\/td>\n<td>Check rated current, voltage, speed, interrupt rating, and whether it is resettable.<\/td>\n<\/tr>\n<tr>\n<td>TP<\/td>\n<td>Test point<\/td>\n<td>A test procedure or net label is needed to understand the expected signal.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Surface-Mount_and_Through-Hole_Parts_What_Is_the_Difference\"><\/span>Surface-Mount and Through-Hole Parts: What Is the Difference?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Surface-mount technology attaches component terminals directly to pads on the board surface. Through-hole technology inserts leads or pins into drilled holes and solders them on the opposite side or inside a plated barrel. Modern PCB assemblies frequently combine both.<\/p>\n\n\n\n<div class=\"wp-block-table\">\n<table>\n<thead>\n<tr>\n<th>Comparison<\/th>\n<th>Surface-Mount Device<\/th>\n<th>Through-Hole Part<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>Board density<\/strong><\/td>\n<td>Supports compact packages and placement on both sides.<\/td>\n<td>Consumes more board area because of drilled holes and lead spacing.<\/td>\n<\/tr>\n<tr>\n<td><strong>Assembly method<\/strong><\/td>\n<td>Well suited to stencil printing, automated placement, and reflow soldering.<\/td>\n<td>Often assembled by insertion, selective soldering, wave soldering, or hand soldering.<\/td>\n<\/tr>\n<tr>\n<td><strong>Electrical behavior<\/strong><\/td>\n<td>Short terminals can reduce unwanted inductance and capacitance at high frequencies.<\/td>\n<td>Longer leads may add parasitic effects but can be acceptable in many low-frequency or power applications.<\/td>\n<\/tr>\n<tr>\n<td><strong>Mechanical loading<\/strong><\/td>\n<td>Strong enough for most components when land patterns and solder joints are designed correctly.<\/td>\n<td>Often preferred for connectors, switches, large transformers, and parts exposed to repeated mechanical force.<\/td>\n<\/tr>\n<tr>\n<td><strong>Repair access<\/strong><\/td>\n<td>Small or leadless packages may require hot air, preheating, magnification, or X-ray inspection.<\/td>\n<td>Large leaded parts are usually easier to probe and replace manually.<\/td>\n<\/tr>\n<tr>\n<td><strong>Typical examples<\/strong><\/td>\n<td>Chip resistors, ceramic capacitors, QFN ICs, BGAs, SOT transistors, compact LEDs.<\/td>\n<td>Pin headers, terminal blocks, large electrolytics, transformers, relays, power connectors.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n<p>The selection is not simply \u201cnew versus old.\u201d It is an engineering decision based on space, volume, assembly process, current, heat, vibration, serviceability, component availability, and expected mechanical stress.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Do_PCB_Parts_Work_Together_in_Functional_Circuit_Sections\"><\/span>How Do PCB Parts Work Together in Functional Circuit Sections?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Components are easier to understand when they are grouped by circuit function instead of viewed as isolated packages. Most boards contain several recognizable zones.<\/p>\n\n\n\n<ul class=\"wp-block-list checklist\">\n<li><strong>Input protection:<\/strong> connector, fuse, TVS diode, reverse-polarity device, common-mode choke, and filtering capacitors.<\/li>\n\n\n\n<li><strong>Power conversion:<\/strong> regulator IC, MOSFET, inductor, diode, feedback resistors, and input\/output capacitors.<\/li>\n\n\n\n<li><strong>Processing and control:<\/strong> MCU, FPGA, processor, memory, reset circuit, decoupling capacitors, and programming header.<\/li>\n\n\n\n<li><strong>Clock generation:<\/strong> crystal or oscillator, loading capacitors, and short controlled traces to the clock pins.<\/li>\n\n\n\n<li><strong>Analog signal conditioning:<\/strong> op-amps, precision resistors, filters, references, ADCs, DACs, and sensor interfaces.<\/li>\n\n\n\n<li><strong>Communication:<\/strong> transceiver ICs, termination resistors, isolation devices, ESD protection, magnetics, and connectors.<\/li>\n\n\n\n<li><strong>Load driving:<\/strong> MOSFETs, gate drivers, relays, flyback diodes, current-sense resistors, and output terminals.<\/li>\n\n\n\n<li><strong>Test and calibration:<\/strong> test points, jumpers, trim components, debug headers, and fixture contacts.<\/li>\n<\/ul>\n\n\n\n<p>Placement often reveals these zones. Decoupling capacitors sit close to IC power pins. High-current paths use wider copper and cluster near power devices. Sensitive analog circuitry is commonly separated from switching nodes, motors, and fast digital interfaces. Connectors usually define where power and signals enter or leave the assembly.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_Do_You_Build_a_PCB_Parts_List_from_the_Schematic_and_BOM\"><\/span>How Do You Build a PCB Parts List from the Schematic and BOM?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A PCB parts list should not be reconstructed from photographs unless the original documentation is unavailable. The correct source is the approved design database and BOM.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Start with the schematic.<\/strong> Verify that every placed symbol has a reference designator, value, manufacturer part number, and correct electrical connections.<\/li>\n\n\n\n<li><strong>Check the footprint.<\/strong> Confirm package dimensions, pad geometry, pin numbering, thermal pad, courtyard, orientation, and assembly process.<\/li>\n\n\n\n<li><strong>Generate the BOM.<\/strong> Group identical parts without losing location references. A useful BOM includes quantity, designators, description, manufacturer, manufacturer part number, package, rating, tolerance, lifecycle status, and approved alternatives.<\/li>\n\n\n\n<li><strong>Review polarized parts.<\/strong> Diodes, LEDs, electrolytic capacitors, ICs, batteries, connectors, and some sensors need clear orientation control.<\/li>\n\n\n\n<li><strong>Validate supply risk.<\/strong> Check stock, lead time, minimum order, moisture sensitivity, packaging format, compliance, and whether alternates are truly pin- and performance-compatible.<\/li>\n\n\n\n<li><strong>Cross-check assembly data.<\/strong> The BOM, centroid file, assembly drawing, stencil data, and PCB revision must all describe the same product revision.<\/li>\n<\/ol>\n\n\n\n<div class=\"wp-block-table\">\n<table>\n<thead>\n<tr>\n<th>Recommended BOM Field<\/th>\n<th>Example<\/th>\n<th>Reason<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Reference designators<\/td>\n<td>R12, R18, R24<\/td>\n<td>Links the purchased line item to exact PCB locations.<\/td>\n<\/tr>\n<tr>\n<td>Manufacturer part number<\/td>\n<td>Exact orderable code<\/td>\n<td>Prevents ambiguity caused by generic descriptions.<\/td>\n<\/tr>\n<tr>\n<td>Electrical value and rating<\/td>\n<td>10 k\u03a9, 1%, 0.1 W<\/td>\n<td>Defines the performance requirement.<\/td>\n<\/tr>\n<tr>\n<td>Package<\/td>\n<td>0603, QFN-32, SOT-23<\/td>\n<td>Must match the land pattern and assembly capability.<\/td>\n<\/tr>\n<tr>\n<td>Approved substitute<\/td>\n<td>Validated alternate MPN<\/td>\n<td>Supports continuity without uncontrolled substitution.<\/td>\n<\/tr>\n<tr>\n<td>Do-not-populate status<\/td>\n<td>DNP \/ DNI<\/td>\n<td>Prevents optional or tuning positions from being assembled accidentally.<\/td>\n<\/tr>\n<tr>\n<td>Lifecycle and compliance<\/td>\n<td>Active, RoHS, REACH<\/td>\n<td>Reduces redesign risk and supports product requirements.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Are_the_Basic_Steps_of_PCB_Design\"><\/span>What Are the Basic Steps of PCB Design?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/07\/basic-steps-of-pcb-design.jpg\" alt=\"Basic steps of PCB design from requirements analysis and schematic design through PCB layout, design rule checking, Gerber generation, manufacturing, assembly, testing, and validation\"\/><\/figure>\n\n\n\n<div style=\"width: 100%; max-width: 600px; margin: 24px auto 34px;\"><\/div>\n\n\n\n<p>PCB design converts product requirements into a manufacturable and testable assembly. The exact process varies by organization, but the core sequence is stable.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Define requirements.<\/strong> Establish interfaces, supply rails, current, voltage, frequency, mechanical envelope, environment, compliance, cost, expected volume, and test strategy.<\/li>\n\n\n\n<li><strong>Select components.<\/strong> Choose active and passive parts based on performance, availability, lifecycle, package, thermal behavior, and assembly constraints.<\/li>\n\n\n\n<li><strong>Create and review the schematic.<\/strong> Add power architecture, signal conditioning, protection, decoupling, connectors, programming access, net labels, and design notes. Run electrical rule checks.<\/li>\n\n\n\n<li><strong>Build the layer stack and rules.<\/strong> Define board thickness, copper weights, dielectric materials, controlled impedance, clearances, via structures, creepage, and manufacturing limits.<\/li>\n\n\n\n<li><strong>Place components.<\/strong> Start with connectors, mechanical constraints, critical ICs, power stages, memory, clocks, and high-speed interfaces. Place support components close to the pins they serve.<\/li>\n\n\n\n<li><strong>Route and pour copper.<\/strong> Protect return paths, separate noisy and sensitive circuits, control differential pairs, size current paths, and connect power and ground planes intelligently.<\/li>\n\n\n\n<li><strong>Verify the design.<\/strong> Run design rule checks, review 3D fit, check signal and power integrity where required, evaluate thermal paths, and conduct DFM\/DFA\/DFT reviews.<\/li>\n\n\n\n<li><strong>Generate production files.<\/strong> Release Gerber or ODB++\/IPC-2581 data, drill files, netlist, fabrication drawing, stackup, BOM, centroid file, assembly drawings, stencil information, and test requirements.<\/li>\n\n\n\n<li><strong>Prototype, assemble, and test.<\/strong> Inspect the bare board, assemble components, perform AOI or X-ray where appropriate, program firmware, run electrical and functional tests, and feed findings back into the next revision.<\/li>\n<\/ol>\n\n\n\n<p>A clear component library and disciplined revision control connect every stage. A correct schematic with an incorrect footprint can still fail, and a correct layout paired with the wrong BOM revision can still produce the wrong assembly.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Frequently_Asked_Questions_About_PCB_Parts\"><\/span>Frequently Asked Questions About PCB Parts<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>1. What is a PCB and what components does it contain?<\/strong><\/p>\n\n\n\n<p>A PCB is an insulating board with patterned copper conductors, pads, vias, coatings, and markings. When components such as resistors, capacitors, ICs, connectors, and switches are assembled onto it, the result is a PCBA.<\/p>\n\n\n\n<p><strong>2. What are the main parts of a PCB board?<\/strong><\/p>\n\n\n\n<p>The main bare-board parts are the substrate or core, dielectric layers, copper traces and planes, pads, vias, plated holes, solder mask, silkscreen, surface finish, board outline, and mounting features.<\/p>\n\n\n\n<p><strong>3. How can I identify an unknown PCB component?<\/strong><\/p>\n\n\n\n<p>Read its reference designator, package shape, top marking, pin count, polarity mark, and nearby circuit. Then confirm the result with the schematic, BOM, assembly drawing, datasheet, or service documentation.<\/p>\n\n\n\n<p><strong>4. What is the difference between a PCB and a PCBA?<\/strong><\/p>\n\n\n\n<p>A PCB is the fabricated bare board. A PCBA is the assembled board after electronic and mechanical parts have been placed and soldered.<\/p>\n\n\n\n<p><strong>5. Can capacitor values be identified by appearance?<\/strong><\/p>\n\n\n\n<p>Large electrolytic and film capacitors usually carry readable values. Small multilayer ceramic capacitors are often unmarked, so the BOM, schematic, or an appropriate measurement is required. In-circuit measurement may be affected by parallel components.<\/p>\n\n\n\n<p><strong>6. What information belongs in a PCB parts list?<\/strong><\/p>\n\n\n\n<p>Include quantity, reference designators, description, value, tolerance, rating, package, manufacturer, manufacturer part number, approved alternates, lifecycle status, assembly notes, and do-not-populate status where applicable.<\/p>\n\n\n\n<p><strong>7. Do keyboard and GPU PCBs use the same basic parts?<\/strong><\/p>\n\n\n\n<p>Yes. Both use copper features, vias, resistors, capacitors, ICs, connectors, and test points. Their layout priorities differ: keyboards focus on switch geometry and matrix scanning, while GPUs focus on high-current power delivery, high-speed memory routing, and thermal control.<\/p>\n\n\n\n<p><strong>8. How can this guide be saved as a PDF?<\/strong><\/p>\n\n\n\n<p>Open the HTML file in a modern browser, choose Print, and select \u201cSave as PDF.\u201d The print stylesheet removes shadows and formats tables for a cleaner document.<\/p>\n\n\n\n<div class=\"closing\"><strong>Need a manufacturability review or PCB\/PCBA quotation?<\/strong> <a href=\"https:\/\/www.bestpcbs.com\/about\/capability.htm\">EBest Circuit<\/a> can review your Gerber files, BOM, centroid data, stackup, and assembly requirements. Contact <a href=\"mailto:sales@bestpcbs.com\">sales@bestpcbs.com<\/a>.<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Learn the parts of a PCB, including board layers, pads, vias, resistors, capacitors, ICs, connectors, reference designators, and identification tips.<\/p>\n","protected":false},"author":623,"featured_media":31585,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[174],"tags":[6997,6998,2163,6995,6996],"class_list":["post-31591","post","type-post","status-publish","format-standard","hentry","category-bestpcb","tag-parts-of-a-gpu-pcb","tag-parts-of-a-keyboard-pcb","tag-parts-of-a-pcb","tag-parts-of-a-pcb-board","tag-pcb-parts"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/31591","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/users\/623"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/comments?post=31591"}],"version-history":[{"count":5,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/31591\/revisions"}],"predecessor-version":[{"id":31602,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/31591\/revisions\/31602"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/media\/31585"}],"wp:attachment":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/media?parent=31591"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/categories?post=31591"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/tags?post=31591"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}