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Come identificare i comuni componenti dei circuiti stampati
When you switch on a computer, radio, or any other electronic device, you will find a printed circuit board (PCB) with many small components. All of these components have a specific function, and it is important to know how to identify them before learning electronics.
Questo Tecnologia FS tutorial lists the most common PCB components. It talks about their function, look, and how to recognize them. After reading this, you can recognize the major components on a PCB with more confidence.
Componenti elettronici comuni nella scheda PCBA
Senza alcun rispetto di alcun tipo di circuito stampatoI componenti elettronici possono essere collocati solo sullo strato superiore o su quello inferiore del PCBA. Queste parti che compongono la scheda PCBA sono considerate importanti, e prima di cominciare Identificazione dei componenti del PCBdobbiamo conoscere i componenti. I componenti elettronici sono destinati a essere collegati tra loro attraverso tracce sullo strato conduttivo dei PCB per sviluppare un circuito elettronico che svolga la funzione desiderata, ad esempio oscillatore, amplificatore, trasmettitore, ricevitore e wireless.
Following are the main electronic components used more frequently from the simplest PCB a singolo strato to complex PCB multistrato.
Resistore
One of the most common components, resistors slow down the flow of electric current. Think of them like a narrow section of pipe slowing the flow of water. They are used to reduce current, divide voltages, and protect sensitive components like LEDs from burning out.
How to Identify:
- Through-Hole (THT) Resistori: These are the simplest for a beginner. They are small, cylindrical devices with wire leads coming out of each end. They have colored bands on them. This color code is a digit. You can use online calculators or charts to decipher it for you (e.g., Brown-Black-Red = 1,000 Ohms or 1kΩ).
- Surface-Mount (SMD) Resistors: Little, flat, rectangular ceramic chips. They are typically black with a white digit imprinted on the top. The digit is a code. For example, “103” is 10 followed by 3 zeros, and that is 10,000 Ohms or 10kΩ.
L'immagine seguente mostra i simboli dei resistori:
Condensatore
When mentioning the application of capacitors, the first thing people think of is charging and discharging. The capacitor is like a small rechargeable battery that is able to be charged and discharged quickly. It is only its most basic function, yet based on the basic function, different circuit phenomena can be realized, for instance: in a motor, it can produce intense vibration; in a telecamera, a capacitor can be discharged instantly with energy. A few of the most commonly used capacitors in our lives include phase-shift capacitors, electric heating capacitors, coupling capacitors, etc. They are used for smoothing alimentatori, filtering a signal, and timing circuits.
How to Identify: Capacitors come in a myriad of shapes and sizes that can be confusing. We’ll talk about the two most common ones:
- Condensatori elettrolitici: Larger, barrel-like components, usually aluminum-colored with a black or grey sleeve. They have a clear polarity: a stripe on the sleeve marks the negative (-) lead. They are always marked with their value (e.g., 100µF) and voltage rating (e.g., 16V).
- Ceramica Condensatori: Much smaller. Through-hole versions look like tiny, flat disks. SMD versions are small, yellow or tan, rectangular chips. They are non-polarized and typically have a numeric code marking (e.g., “104” = 100,000 pF or 0.1µF).
The symbol for a capacitor is provided by the following figure:
Transistor
Transistors are indispensable PCB components in the produzione elettronica industry, and their numbers are very large. We can simply divide it into triode, diode, thyristor, etc. It has a variety of functions such as detection, rectification, amplification, switching, voltage regulation, signal modulation and so on.
How to Identify: Through-hole transistors are typically in a small black plastic package with three metal leads. They will also have a part number printed on them (e.g., BC547, 2N3904) which you can look up online to know its details. SMD transistors are extremely small, black, flat chips with three leads.
The transistor symbol is illustrated in the figure below:
Induttori
Inductors store energy in a magnetic field when current is sent through them. They resist changes in current and see significant use in power supplies and radio circuits to reject high-frequency signals.
How to Identify: They might look like resistors but tend to be one color like green, blue, or beige with no bands of color. Sometimes you can see the coiled wire inside them. SMD types are tiny, black, rectangular chips. They can have a plain number stamp.
Integrated Circuits (ICs) / Microchips
An IC is not a single device but a vast collection of tiny transistors, resistors, and other components built onto a single piece of silicon. They perform complex functions as a complete circuit (e.g., a microcontroller, amplifier, or logic chip).
How to Identify: They are the “black rectangles” with a lot of legs (pins). They cannot be overlooked. They always have a part number engraved on top (e.g., “ATMega328,” “LM358,” “74HC00”). The key to recognizing an IC is to look up this number on the internet to find its datasheet.
How to Classify PCB Components
Method 1: Active vs. Passive Components
In order to facilitate management, we generally further classify componenti elettronici into two types based on various factors like power gain, functions, nature of the source, and controlling the flow of current.
Componenti attivi
Questi componenti forniscono energia al circuito invece di utilizzarla, per questo sono chiamati componenti attivi e l'energia prodotta è sotto forma di tensione e corrente. I componenti attivi sono anche chiamati donatori di energia. Utilizzano l'energia di una fonte esterna per svolgere la loro funzione,
Esempi di componenti attivi sono i transistor, i diodi e i circuiti integrati (IC).
Componenti passivi
I componenti elettronici passivi utilizzano l'energia che i componenti attivi forniscono al circuito. Questi componenti si limitano a immagazzinare energia e non sono in grado di fornirla come i componenti attivi. I componenti passivi sono anche chiamati accettori di energia.
Ne sono un esempio i resistori, i condensatori e gli induttori.
| Caratteristica | Componenti attivi | Componenti passivi |
|---|---|---|
| Potenza | Can control e amplify power. They often require a power source to function. | Cannot control or amplify power. They can only absorb or store it. |
| Funzione | Act as switches, amplifiers, oscillators. | Resist, store, or filter energy. |
| Esempi | Transistors, ICs, Diodes, LEDs | Resistors, Capacitors, Inductors |
Method 2: Through-Hole (THT) vs. Surface-Mount (SMD)
Se si osserva attentamente la scheda PCBA in mano, si può notare che i componenti elettronici sullo stesso circuito utilizzano processi di confezionamento diversi. In parole povere, uno viene inserito direttamente nel foro della scheda PCB, mentre l'altro viene saldato alla scheda PCB. Pertanto, i componenti PCB possono essere suddivisi in due categorie in base al loro metodo di confezionamento.
Componente con foro passante
Through-hole components refer to a type of component that is soldered on the surface of a PCBA through plug-in and saldatura a onda, and usually we also call it a Componente DIP. Quasi tutti i componenti elettronici hanno un contenitore a foro passante. Questi pacchetti hanno pin abbastanza lunghi da passare dallo strato superiore a quello inferiore e da essere saldati sullo strato inferiore con il PCB. Sono anche chiamati pacchetti multistrato o Assemblaggio DIP. Per un pacchetto di questo tipo, il routing può essere effettuato sia sullo strato superiore che su quello inferiore o su altri strati multipli di PCB.
Dispositivo a montaggio superficiale (SMD)
Come suggerisce il nome, si tratta di Componenti SMD montati su un solo lato del PCB, per questo motivo anche il loro instradamento viene effettuato su quello stesso lato o può essere spostato su un altro strato usando vias nel PCB. In questo pacchetto sono presenti quasi tutti i componenti elettronici.
Electronic component either through-hole or SMD is used according to need. Their working principle and function resemble but differ in size and soldering methodology.
| Caratteristica | Through-Hole (THT) | Surface-Mount (SMD) |
|---|---|---|
| Montaggio | Leads are inserted into holes drilled in the PCB and soldered on the other side. | Soldered directly onto cuscinetti on the surface of the PCB. |
| Board Space | Larger, uses more space on both sides of the board. | Much smaller, allows for incredibly dense and compact modern devices. |
| Montaggio | Easier for hand-soldering and prototipazione. | Requires precise automated machines for assembly, but is faster for produzione di massa. |
Practical PCB Component Identification Tips
- Get Your Hands On Old Electronics: The best way to learn is to get a broken radio, DVD player, or old computer scheda madre (just be sure it’s not plugged in!). With a screwdriver, break it down and try to identify each component on the board.
- Use the Right Tools:
- A magnifying glass or jeweler’s loupe is necessary for reading the tiny codes on SMD components.
- Your friend is a multimeter. You can use it to measure resistor values, check if a diode works, and check for continuity (no gaps in the connections).
- Decode Part Numbers: For any transistor or IC, type the number on the part into a search engine and the term “datasheet” (e.g., “NE555 datasheet”). This document tells you everything about the part.
- Trace the Traces: Look at the thin copper lines (traces) between components. This may enable you to notice that components are grouped into functional blocks (e.g., power section, audio output section).
Conclusione
Proficiency in the art of PCB component identification will take your repair, troubleshooting, and even design skills to electronic components to greater heights. Once you’ve mastered the art of component identification and are set to bring your circuit concepts to life, you would require a trustable manufacturing partner. Tecnologia FS offers an entire range of Fabbricazione di PCB e servizi di assemblaggio, including approvvigionamento dei componenti, from simple single-board prototypes to complex multi-layered projects. Contact us today for a quick quote and let us help you create your electronic innovations.
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