While it is a great hobby, do-it-yourself computer kits require some knowledge of what printed circuit board parts and what complaints go on them. All electric equipment has one or more circuit boards. These board, in turn, contain several components that work together to create the desired effect. Each component modifies and manages the current and voltages through them.
Many are standardized off-the-shelf parts that you can quickly identify, find and purchase. Other components are more proprietary to your project, making them much more difficult to find. You can do PCB Assembly much easier after knowing any kinds of parts you need.
However, how do you identify those parts? You need a clear component identification list to help you find the parts you need at a price you can afford. This article will give you some ideas on where to start.
1、Circuit Board Components Identification
All electronic devices comprise of several different parts. These parts work together to modify and manage current and voltage to produce the desired effect. Circuit boards act as backbones keeping everything connected and compacted in a form that is easy to use.
Most of these components are standardized off-the-shelf parts that you can quickly identify, find, and purchase with easy-to-understand shapes, sizes, and colors. Other components are more proprietary to your project, making them much more difficult to find.
An excellent schematic diagram can help you identify the parts you need and when. These drawings provide a snapshot of your circuit using symbols to represent each component type. Straight solid lines mark the wiring and connectors between components. Zigzag lines represent resistors. Capacitors are short parallel likes and so forth. To learn more about how to customize the harness, check out the following article: Harness: The ultimate custom guide.
A functional schematic will also use letters and numbers to label each component's position on the circuit as well. For instance, the eleventh resistor is "R11" on the schematic.
Figure 1: Standard PCBA Component Labels
The circuit boards themselves are simple enough. They are just thin, plastic, rectangular plates or polyester film. Most are blue or tan, though you can find a few other colors out there3 as well. Regardless of the color, new boards have one or more layers of conductive copper foil.
Most boards will only have this foil on one side, but you may come across double-sided PCBs on occasion. Some professionally-made PCs may have many layers of copper. Either way, you must use particular etching solutions to turn the foil into your circuit's wiring.
However, you can buy pre-etched boards and skip this step altogether. You need to get the right –sized board for your needs and case.
Resisters limit the flow of current through a circuit. These small, horizontal cylinders often bear four or five colored stripes that help identify their resistance and tolerance. Larger resistors may have this information written on them as well.
Their schematic systems can also have this information printed in words as well. In either case, PCBs use R to note resistors.
These variable resistors are usually marked in ohms using three digits. The first two digits are the significant figures with the third proving the power of 10 multipliers.
Potentiometers also have a letter code to indicate the resistance change, and a VR for variable resistor marked on them somewhere.
Capacitors store electric charge. These components come as small disk-shaped gumdrops or large cylinders. In either case, the information is printed directly onto them. PCBs, use C to make capacitors.
Connectors are how your device connects to other devices as well as to other boards in the same machine. These components tend to have plastic shells and one or more pins that serve as the links between your device and the cables.
Diodes one-way electrical components with a band that indicated the current direction. You can find their specs on their shells. You may also come across LEDs and Zener diodes as well.
Diagrams use an arrowhead and a bar to indicate diodes while circuit boards use D or CR. The arrow points in the direction of the current.
A LED, or light emitting diode, is a component that can give off light. You can find them in single and multi-color and low and high-power varieties. Low-power, single color LEDs are the most common. They often come in their respective colors, but not always.
They will only have two terminals, a cathode, and an anode. Multi-color ones have more than one color and a set of terminals for each color. High-power LED has a large metal casing to dissipate the extra heat. LEDs use the diode symbol on diagrams.
Relays are electronic switches. Powered relays are open while disconnected relays are closed. These components typically have plastic shells with their specification written on them. Most boards use "K" to label relays.
Transistors are a particular type of switch. You can identify them by their three terminals and their "D" shape. Circuit boards often use Q to indicate transistor locations.
Transistor diagrams are circles with three leads. Inside the circle, one point goes directly to a bar, while the other leads branch off diagonally from the bar with one of them containing an arrow.
Essentially loops of wire, inductors are often difficult to identify. You can find them either as a raw wired coil or color coded. In either case, you should test the components before using them. Fortunately, PCBs use an L to indicate an inductor.
Crystals and Oscillators
Marked on boards with an X or Y, these natural clocks keep our electronic devices working smoothly and on time. The unique appearance of a crystal oscillator makes these components the easiest to identify. They also have their specification written on them.
Integrated Circuit (IC)
These complete circuits-on-a-chip will take some effort to identify correctly, as several different types of ICs can come in the same package. Marked as U or IC on most circuit boards, you often need to look up the device's datasheet to find the information.
Datasheets offer a schematic of their devices and are typically found online. Circuit diagrams use rectangular blocks to represent these components.
2、Common PCBA Components
Most PCBs don't have every type of component. Most circuits only need a handful to work with each circuit requiring different components. Still, there is some overlap, and there are a few common fractures on every circuit board you build.
These common PCBA components are:
2.1 Ball Grid Array (BGA)
Ball Grid Array (BGA) refers to a particular type of surface PCBA which is used to permanently mount devices, such as microprocessors, to printed circuit boards.
A BGA has some advantages over other methods, and as such, it has become a favorite technique used in the manufacturing of integrated circuits and electronic devices.
A common form of electronic manufacturing, ball grid arrays derived from pre-existing pin grid array (PGA) technologies. Instead of utilizing pins to conduct electrical signals from the circuit board, a ball grid array makes use of tiny drops of solder.
These balls of solder are placed evenly apart on the board in an array, or regular grid and gently heated in a specialist oven. Surface tension ensures that the components are kept in position.
2.2 Quad Flat No-Lead (QFN)
The QFN (Quad Flat No-lead) package is probably the most popular semiconductor package today because of four reasons: low cost, small form factor and excellent electrical and thermal performance.
Like any other semiconductor package, a QFN package functionality is to connect (both physically and electrically) silicon dies (the ASIC) to a printed circuit board (PCB) using surface-mount technology.
QFN is a lead frame-based package which is also called CSP (Chip Scale Package) with the ability to view and contact leads after PCBA.
The QFN can have a single or multiple rows of pins. The single row structure is formed by a punch singulation, or a saw singulation process, both of these methods divide a broad array of packages into individual packages.
The multi-row QFN uses an etching process to realize the wanted number of rows and pins; these are then also singular, typically by a saw.
The benefits that come from choosing the QFN packages include a decreasing lead inductance due to optimally short bond wires, lightweight, thin profile and small sized "near chip scale" footprint.
Moreover, thanks to the exposed copper die pad; the QFN is perfect for many new applications that need better performance in size.
The solder resists with LPKF ProMask and PCBA prints with LPKF ProLegend.
Solder Resist Masks and PCBA Print for In-House Prototyping Solder resist is a fundamental requirement for soldering certainty –, especially for SMT.
The professional quality solder resists masks can quickly and effectively be applied to structured PCBs using the LPKF ProMask. The solder resist mask is printed onto transparency from the CAD program, transferred onto the PCB, and developed.
In four simple steps, the structured PCB is given a perfect surface finish for soldering without short circuits. PCBA print uses a similar process. ProMask and ProLegend include all the tools and materials required for perfect results.
LPKF ProMask and LPKF ProLegend are essential tools for quick, easy and inexpensive PCB prototyping or small batches. A photo-optical exposure process transfers all structures or legends onto the PCB in just a few steps.
LPKF ProMask and ProLegend Provide Professional Finishing in Four Simple Steps:
1. Print photo template
The photo template with the desired layout is printed onto a transparency using LPKF CircuitPro and a standard laser printer.
2. Apply paint
Mix the solder resist from the pre-proportioned paint and hardener.
Apply the solder resist onto the structured PCB with the included roller.
The PCB is then pre-dried in a convection oven for 10 minutes.
3. Expose photo template
Position the photo template on the PCB and place both in the UV-exposer.
Activate the laser setter for 30 seconds. Remove the PCB and remove the photo template.
4. Develop and harden solder resist mask
Prepare the developing bath with the developing powder and hot water.
Use a brush to release the unexposed solder resist in the developing bath. The solder resists then hardened and cleaned in a convection oven for 30 minutes. A powder pH-conditioner then neutralizes all chemical components for eco-friendly disposal.
This list may change as integrated circuit chips come more common in the hobby market. ICs are already the mainstay components on most professional boards and in any device that needs some computational functionality.
3、Choosing PCB Components
The best PCB designs use the best components for the job. There is no other way to do it. With the right PCB components, your circuit will provide fewer avenues for failure and cost the least to make.
If you do not choose the components wisely, you may run into problems later on that can increase your project's costs significantly, especially if some of the components are rare and expensive.
There are a few things you can do to ensure that you only use the right components for your project. You just following these rules
1. Plan out your project with schematic diagrams.
Before you touch any real components, you should complete your project virtually. An excellent schematic diagram will show you what components you need and where you need them.
You can then use the schematic to create a Bill of Material for the components with their appropriate dimensions and quantities.
Figure 2: Standard schematic symbols for common PCBA components
2. Select the right mounting.
Surface mounting costs the least, but it is generally only viable with small components that are machine-assembled. If you mount your components by hand, you want to use a through-hole mounting system that allows for more significant components.
3. Space components concerning their requirements.
Each component has a clearance requirement. You need to make sure there is enough space around them so they can dissipate heat and prevent accidental short circuits.
Please note that power parts have the highest clearance requirements, and their heat can physically warp the underlying PCB.
4. PCB components have soldering requirements.
You want to know if you can solder things by hand or through a reflow oven.
That is because you want significant, through-hole components for your significant functions if you will hand solder your board, only moving to lighter components for the smaller areas and functions.
By following this short list of rules, you will streamline your projects with only the necessary components. It will not only save you money, but it will free up more of your time that you can use on other projects or for testing your project before you release it.
4、Electronic Parts & General Supplies
Having an excellent PCB plan is nothing without the components to build them. However, recent changes in the industry may make it difficult to find the parts. For most hobbyists, you must buy your parts online or scavenge the parts from other devices.
Each method has its pros and cons, and you are going to have to expect to take a significant amount of time to gather everything you need before you can begin. Gathering supplies is the most extended aspect of PCB building, and there is no real way to make it go faster.
Generally, you want a list of go-to suppliers that you know will have most if not all the parts you need. While you can find great lists online, only you can make a list for you.
That is because, you may have a favorite local shop that can get you the parts as you need them, instead of waiting for the parts to ship through the mail.
Either way, once completed, your electronics parts shop list will serve as a quick reference to get your projects going, saving you time and money for more critical tasks.
If you do not have a parts supplier near you, nor can you find the parts online, you are going to get the parts from pre-existing boards and devices.
Thus, you need to know how to identify the parts of these old donor boards so you can recycle anything that still works. While newer boards should use the standards mentioned above, older boards may use more restrictive means of identifying their components.
Fortunately, you should be able to find the schematics of those older bards online.
4.1 Television Circuit Board Components Identification
Old televisions are a public source of donor electronics parts. These devices are usually obsolete to serve as televisions and usually just get tossed in the trash. That also means that you can often get these boards for free in many cases.
You want to make sure their components still work before reusing them, but they are comfortable and fun options when you need PCB parts for your project.
Generally, you should only worry about the electrolytic capacitors and resisters. These components tend to the age when heated which can permanently change their values.
The rest of the components should be okay, though you want to ensure nothing burned out. You must be careful when removing them as you could damage their leads, rendering them useless.
For the most part, old television components have what they are printed on them. Plus, common components still look like they did in these own machines as well. The only real differences you will see on the old TV boards is the rectangular resistors.
Some odd TV components you may find include:
• AM IF resonator. Usually a small orange box, this is an oscillator crystal. They usually oscillate at 455 KHz, but you can also find 500 or 560 KHz resonators.
• Tantalum electrolytic capacitors. They are small and blue.
• Ceramic resonators. These three-pin components act as filters for audio signals.
• High-voltage resistors. These are large white boxes with information printed on them.
• Delay line. These large component delay signals through a circuit.
4.2 Mobile Circuit Board Components
Mobile circuit boards are generally more comfortable to use than television boards. For one, nearly all of them use modern electronic component identification standards. So, you should already have the skills necessary to find what you need.
Secondly, old mobile devices are more accessible and cheaper to find. You may have a few old devices yourself as most people tend to upgrade their mobile technology regularly.
Still, it is always a good idea to have some idea what each part does before you crack open a vintage iPhone. Your average phone has a surprisingly large amount of circuitry inside, and most of it optimized for performance.
You can find both analog and digital electronics sitting and working next to each other.
While multi-board devices do exist, most mobile electronics sit on a single PCB. However, this PCB is divided into two different sections: network and power. Each section has its own needs and function, so you want to keep them in mind when hunting for parts.
The Network half contains all the radio frequency elements and is the crucial circuitry that makes the whole mobile device work. At the top, the antenna and antenna point sit apart from the rest of the circuit.
Below the antenna point, you will find the transmitter and receiver circuits.
Notable components in this area are:
• Antenna switch. Located just below the antenna point, the switch has metallic and non-metal parts with 16 points or legs. It is white in GSM-network devices, but golden in CDMA devices. Please note that some devices merge their switch into their PFO.
• Power frequency oscillator (PFO). Also called the power amplifier (PA) and bandpass filter, the PFO is a crystal oscillator that manages the device’s wireless signal. It is either located next to the antenna switch or inside it.
• 26 MHz Crystal Oscillator. Also called the network crystal. It generates the transmission signals. You will find this metallic box near the PFO.
• Network IC. The network IC provides the signal transmission logic. Usually, you will find it below the antenna switch and PFO, but some devices merge this IC into the CPU.
• RX and TX Filters. These black boxes filter and regulate the incoming and outgoing signals respectively.
• Voltage-controlled Oscillator (VCO). This IC converts the signal between analog and digital.
4.3 The Power Section
The power section is the heart of the mobile device, containing all of its computing components.
• Power IC. Encircled by several brown-colored capacitors, the power IC It manages the battery to power the entire device. Some devices may have two of this circuits.
• Central Processing Unit (CPU). The CPU is the largest IC on the PCB.
• Flash IC. Located next to the CPU, the Flach IC is the ROM that provides the preconfigured software.
• ROM and RAM. The read-only and random-access memory ICs are located next to the CPU.
• Charging IC: Located near resister 22, the charging IC regulates battery recharging.
• Audio IC. Located next to the Power IC, this is the mobile devices sound chip.
• Real Time Clock (RTC): Located next to the Power IC, this silicon oscillator is the clock of the PCB.
• Logic IC. The logic IC operates the ringer, vibrator, and LEDs. There is no universal location for it though.
5、Understanding The Electronic Components Market
For components distributors, manufacturers of electronic equipment and many others. Having an understanding of the electronic components market is necessary. In times of boom, components are more laborious to source-prices rise and lead times significantly increase.
Especially for semiconductors, in times of recession prices fall and availability increases. Planning to enable manufacturers to keep production lines running while also keeping costs down.
5.1 Significant Factors For The Tendency Of Electronic Component
Many known factors affect the overall market. Analysis of existing growth trends globally and for different countries is one factor. Another is the new and growing electronics industry sectors. Automotive and the new Internet of Things sectors are expected. To grow significantly driving overall growth.
Sectors like mobile and fixed telecommunications, computer devices of all forms. Moreover, many others are well established and likely to grow less.
5.2 However, Many Unknowns Could Affect The Economic Conditions That Govern The Overall Global Economy.
The output of the electronics industry is multiplying.
As well as devices based on acoustoelectronics and magnetoelectronics is increasing, rapid expansion has distinguished the production of such equipment as microcomputers, color picture tubes, electronic calculators (including programmable calculators).
As well as video recorders, electronic watches, high-quality stereo systems.
Many of these innovations, such as the transistor, had their origins in military research. Which needed increasingly sophisticated electronic devices for modern high-tech warfare.
Consumer electronics industry is a primary end-use market for electronic components. Also, therefore the recent spurt in demand for electronic devices. Particularly in developed markets, is lending significant traction to the global electronic components market.
With electronic device manufacturers increasing their production capacity to meet the growing demand for these. Such as the growing demand for Wireless Communication Equipment.
Data Network Infrastructure need multilayer PCBs. Industrial expansion in emerging markets and Electronic medical industry. Also, increase the market for electronics components.
So that more competitive of the electronics industry will be. Also, the costs and markets of electronics components will significantly increase. So more innovative technology to make the right component selection is required.
A fully functioning circuit board contains several components that work together to achieve a specific function. Knowing how to identify these components will help you plan out and build your next project.
Beyond that, you need to know their limits, as well as not all components, are needed in every project. Through this process, you will have a PCB project that you can complete under budget in a reasonable amount of time.
If you need components, you can scavenge them from old PCBs such as those found in old televisions and mobile device, or you can buy them from a reputable supplier.
Buying the parts may cost more, but it is the only way to ensure that all your components work before you solder them on to your board.
If you need assistance finding your components, you can contact us for advice. We provide a one-stop turnkey PCBA service, and we are here to help you purchase all your PCBA supplies. All of our assembly components come from reputable Digikey and Mouser companies.
Therefore, you can rest assured that all of our components have the best quality and price on the market.