Gudiga wareegga daabacan (PCB) waxaa laga helaa ku dhawaad ​​nooc kasta oo ah qalab elektaroonik ah. If there are electronic components in a piece of equipment, they are also embedded in various sizes of PCB. In addition to fixing various small parts, the main function of the PCB is to provide electrical connections between the components. As electronic equipment becomes more and more complex, more and more parts are needed, and the wiring and parts on the PCB become more and more dense. PCB -ga caadiga ah wuxuu u eg yahay wax sidan oo kale ah. Bare Board (without parts on it) is also often referred to as “Printed Wiring Board (PWB).

The substrate of the board itself is made of a material that is insulated and resistant to bending. The small line material that can be seen on the surface is copper foil. Originally, the copper foil is covered on the whole board, and the middle part is etched away in the manufacturing process, and the remaining part becomes a network of small lines. These lines are called conductors or conductors and are used to provide electrical connections to parts on the PCB.

To secure parts to the PCB, we solder their pins directly to the wiring. PCB -ga aasaasiga ah, qaybaha ayaa ku urursan hal dhinac iyo fiilooyinku waxay ku urursan yihiin dhinaca kale. So we need to make holes in the board so that the pins can go through the board to the other side, so the pins of the parts are welded to the other side. Because of this, the front and back sides of a PCB are called Component Side and Solder Side respectively.

Haddii ay jiraan qaybo PCB -ga ku jira oo laga saari karo ama dib loo gelin karo soo -saaridda kadib, Socket waxaa loo isticmaali doonaa in lagu rakibo qaybaha. Because the socket is directly welded to the board, the parts can be arbitrarily disassembled. A ZIF (Zero InserTIon Force) plug allows parts to be inserted and removed easily. The lever next to the socket can hold the parts in place after you insert them.

To connect two PCBS to each other, an edge connector is commonly used. Farta dahabka ah waxaa ku jira tiro ka samaysan naxaas qaawan oo dhab ahaantii qayb ka ah taararka PCB -ga. Caadi ahaan, si aan isugu xirno, waxaan gelineynaa farta dahabka ah ee hal PCB godka ku habboon (oo sida caadiga ah loogu yeero booska ballaarinta) PCB -ga kale. In computers, display cards, sound cards, and similar interface cards are connected to the motherboard by means of a gold finger.

Midabka cagaaran ama bunni ee PCB -ga waa midabka maaskarada iibiya. This layer is an insulating shield that protects the copper wire and prevents parts from being welded to the wrong place. Shaashad kale oo xariir ah ayaa lagu daabici doonaa lakabka iska caabinta alxanka. It is usually printed with words and symbols (mostly white) to indicate the position of the parts on the board. Screen printing surface is also known as icon surface

Halyeey).

Guddiyada hal dhinac ah

Sidii aan soo sheegnay, PCB -ga aasaasiga ah, qaybaha ayaa ku urursan dhinac dhinacna fiilooyinku waxay ku urursan yihiin dhinaca kale. Because the wire appears on only one side, we call this TYPE of PCB single-sided. Sababtoo ah guddiyada keli ah waxay lahaayeen xannibaadyo badan oo adag oo ku saabsan naqshadda wareegga (maxaa yeelay waxaa jiray hal dhinac oo keliya, xariggu ma dhaafi karo waxayna ahayd inuu qaato waddo gooni ah), kaliya wareegyada hore ayaa adeegsaday looxyada noocaas ah.

Guddiyada Labada Dhinac leh

Guddiga wareegga ayaa leh labada xarig ee xarig. But in order to use both wires, there must be proper electrical connections between the two sides. “Buundadan” u dhaxaysa wareegyada waxaa lagu magacaabaa daloolka hagaha (VIA). Daloollada hagaha waa godad yaryar oo ku jira PCB -ga oo laga buuxiyey ama lagu daboolay biro lagu xiriirin karo fiilooyinka labada dhinacba. Because a dual panel has twice the area of a single panel, and because the wiring can be interlaced (it can be wound around to the other side), it is better for more complex circuits than a single panel.

Multi-layer Boards

Si loo kordhiyo aagga la xiriiri karo, ayaa looxyo fiilooyin badan oo hal dhinac ah ama laba dhinac leh. Boodhka isku -xidhka badan wuxuu adeegsadaa dhowr gole oo laba jibbaar ah, oo lakab ka -daboolid ayaa la dhigaa inta u dhexeysa guddi kasta oo la isku dhejiyo (la cadaadiyo). The number of layers of the board represents several independent wiring layers, usually an even number of layers, including the outermost two layers. Most motherboards are built with four to eight layers, but it is technically possible to build up to 100 layers of PCBS. Inta badan kuwa waawayn ee waawayn waxay adeegsadaan dhawr lakab oo ah boodhadhka hooyada, laakiin way ka dhammaadeen isticmaalkooda maadaama lagu beddeli karo rucuubyo kombiyuutarro caadi ah. Because the layers in a PCB are so tightly integrated, it’s not always easy to see the actual number, but if you look closely at the motherboard, you might be able to.

The guide hole (VIA) we just mentioned, if applied to a double panel, must be through the entire board

But in a multilayer, if you only want to connect some of the lines, the guide holes may waste some of the line space in the other layers. Buried vias and Blind vias avoid this problem because they only penetrate a few layers. Blind holes connect several layers of internal PCBS to surface PCBS without penetrating the entire board. Buried holes are only connected to the internal PCB, so light is not visible from the surface.

In a multilayer PCB, the entire layer is directly connected to the ground wire and the power supply. So we classify the layers as Signal, Power or Ground. If the parts on the PCB require different power supplies, they usually have more than two power and wire layers.

Farsamada baakadaha qayb

Iyada oo loo marayo Hole Technology

The technique of placing parts on one side of the board and welding the pins to the other side is called “Through Hole Technology (THT)” encapsulation. This part takes up a lot of space and one hole is drilled for each pin. Markaa kala -goysyadoodu dhab ahaantii waxay qaadanayaan meel labada dhinacba ah, kala -goysyada wax iibiyana aad bay u weyn yihiin. Dhinaca kale, qaybaha THT waxay si fiican ugu xiran yihiin PCB marka loo eego qaybaha Surface Mounted Technology (SMT), oo aan gadaal ka hadli doonno. Sockets like wired sockets and similar interfaces need to be pressure-tolerant, so they are usually THT packages.

Surface Mounted Technology

For Surface Mounted Technology (SMT) parts, the pin is welded on the same side with the parts. This technique does not drill holes in the PCB for each pin.

Qaybaha dhejiska ah ee dusha sare ayaa xitaa laga alxan karaa labada dhinac.

SMT sidoo kale waxay leedahay qaybo ka yar THT. Compared to PCB with THT parts, PCB with SMT technology is much denser. SMT package parts are also less expensive than THT’s. So it’s no surprise that most of today’s PCBS are SMT.

Because the solder joints and pins of parts are very small, it is very difficult to weld them manually. However, given that current assembly is fully automated, this problem will only occur when repairing parts.

The design process

Naqshadeynta PCB, dhab ahaantii waxaa jira tallaabooyin aad u dheer oo la mari karo ka hor inta aan la xidhin xargaha rasmiga ah. Kuwa soo socda ayaa ah habka naqshadeynta ugu weyn:

The system specifications

First of all, the system specifications of the electronic equipment should be planned. It covers system functionality, cost constraints, size, operation and so on.

System function block diagram

Tallaabada xigta waa in la abuuro jaantuska xannibaadda ee nidaamka. Xidhiidhka ka dhexeeya barxadaha waa in sidoo kale la calaamadeeyaa.

Divide the system into several PCBS

Dividing the system into several PCBS not only reduces the size, but also gives the system the ability to upgrade and swap parts. The system function block diagram provides the basis for our segmentation. Computers, for example, can be divided into motherboards, display cards, sound cards, floppy disk drives, power supplies, and so on.

Go’aanso habka baakadaha loo isticmaalo iyo cabbirka PCB kasta

Once the technology and the number of circuits used for each PCB has been determined, the next step is to determine the size of the board. If the design is too large, then packaging technology will have to change, or re-split the action. Tayada iyo xawaaraha jaantuska wareegga waa in sidoo kale la tixgeliyaa marka la dooranayo farsamada.

Draw schematic circuit diagrams of all PCB’s

The details of the interconnections between the parts should be shown in the sketch. PCB -ga nidaamyada oo dhan waa in la qeexaa, badankooduna waxay adeegsadaan CAD (Naqshadaynta Kombiyuutarka) hadda. Here is an example of a CircuitMakerTM design.

Jaantuska jadwalka ee wareegga PCB

Preliminary design of simulation operation

To ensure that the designed circuit diagram works, it must first be simulated using computer software. Such software can read blueprints and show how the circuit works in many ways. This is much more efficient than actually making a sample PCB and then measuring it manually.

Place the parts on the PCB

The way parts are placed depends on how they are connected to each other. Waa inay ku xiran yihiin waddada sida ugu hufan. Efficient wiring means the shortest possible wiring and fewer layers (which also reduces the number of guide holes), but we’ll come back to this in actual wiring. Here is what the bus looks like on a PCB. Placement is important in order for each part to have perfect wiring.

Test wiring possibilities with correct operation at high speed

Qaar ka mid ah software -ka kombiyuutarka ee maanta ayaa hubin kara in meelaynta qayb kasta si sax ah loogu xiriiri karo, ama la hubin karo inay si sax ah ugu shaqayn karto xawaare sare. Tallaabadan waxaa loogu yeeraa isku -dubaridka qaybo, laakiin aad uguma sii socon doonno tan. Haddii ay dhibaato ka haysato naqshadda wareegga, qaybo ayaa sidoo kale dib loo hagaajin karaa ka hor inta aan wareegga laga dhoofin duurka.

Wareegga dhoofinta ee PCB

The connections in the sketch will now look like wiring in the field. Tallaabadan badiyaa si otomaatig ah ayey isu beddeshaa, in kasta oo isbeddelada gacanta loo baahan yahay badiyaa. Below is the wire template for 2 laminates. Khadadka gaduudan iyo buluugga ah waxay matalaan lakabka qaybaha PCB iyo lakabka alxanka siday u kala horreeyaan. The white text and squares represent the markings on the screen printing surface. Dhibcaha iyo wareegyada gaduudan waxay u taagan yihiin godad qodis iyo hagitaan. Dhinaca midigta fog waxaan ku arki karnaa farta dahabka ah ee dusha alxanka ee PCB. The final composition of this PCB is often referred to as the working Artwork.

Each design must conform to a set of rules, such as minimum reserved gaps between lines, minimum line widths, and other similar practical limitations. Tilmaamahaani waxay ku kala duwan yihiin hadba sida xawaaraha wareegga, xoogga ishaarta la gudbiyo, dareenka wareegga ee isticmaalka awoodda iyo buuqa, iyo tayada maaddada iyo qalabka wax soo saarka. If the strength of the current increases, the thickness of the wire must also increase. In order to reduce PCB costs, while reducing the number of layers, it is also necessary to pay attention to whether these regulations are still met. Haddii loo baahdo in ka badan 2 lakab, lakabka korontada iyo lakabka dhulka ayaa badiyaa loo isticmaalaa si looga fogaado signalada gudbinta ee lakabka signalada inay saameyso, waxaana loo adeegsan karaa gaashaanka lakabka signalada.

Wire after circuit test

In order to be sure that the line is working properly behind the wire, it must pass the final test. Baaritaankani wuxuu kaloo hubiyaa isku -xirnaanta khaldan, dhammaan xiriiriyadu waxay raacaan jaantuska sawirka.

Samee oo fayl garee

Sababtoo ah hadda waxaa jira qalabyo badan oo CAD ah oo loogu talagalay naqshadeynta PCBS, soo -saareyaashu waa inay lahaadaan astaan ​​u dhiganta heerarka kahor inta aysan soo saarin looxyada. There are several standard specifications, but the most common is the Gerber Files specification. A set of Gerber files includes a plan of each signal, power and ground layer, a plan of the solder resistance layer and the screen printing surface, and specified files of drilling and displacing.

Electromagnetic compatibility problem

Aaladaha elektiroonigga ah ee aan loogu talagalin qeexitaannada EMC waxay u badan tahay inay soo saaraan tamarta electromagnetic oo ay farageliyaan qalabka u dhow. EMC waxay ku soo rogtaa xadka ugu sarreeya faragelinta elektromagnetic (EMI), aagga elektromagnetiga (EMF) iyo faragelinta soo noqnoqoshada raadiyaha (RFI). Xeerkani wuxuu xaqiijin karaa hawlgalka caadiga ah ee qalabka iyo qalabka kale ee u dhow. EMC waxay ku soo rogtaa xadad adag xaddiga tamarta la kala firdhin karo ama laga gudbin karo hal qalab ilaa mid kale, waxaana loogu talagalay in lagu yareeyo u nuglaanta EMF, EMI, RFI, iyo wixii la mid ah. In other words, the purpose of this regulation is to prevent electromagnetic energy from entering or emanating from the device. This is a very difficult problem to solve, and is usually solved by using power and grounding layers, or putting PCBS into metal boxes. The power and ground layers protect the signal layer from interference, and the metal box works equally well. We won’t go too far into these issues.

The maximum speed of the circuit depends on EMC compliance. EMI -ga gudaha, sida lumitaanka hadda u dhexeeya kaariyeyaasha, ayaa kordha marka soo noqnoqoshada kor u kacdo. Haddii farqiga hadda u dhexeeya labaduba uu aad u weyn yahay, hubi inaad dheereysato masaafada u dhexeysa. This also tells us how to avoid high voltage and minimize the current consumption of the circuit. Heerka dib -u -dhaca ee xarigga ayaa sidoo kale muhiim ah, sidaa darteed dhererka gaaban, ayaa ka sii fiican. Sidaas darteed PCB yar oo leh fiilooyin fiican ayaa si fiican ugu shaqayn doona xawaare ka sarreeya PCB -ga weyn.