Kusindikizidwa bolodi dera (PCB) amapezeka pafupifupi pazida zamagetsi zamtundu uliwonse. 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 wamba imawoneka chonga ichi. 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. Pa PCB yoyambira, zidutswazo zimakhazikika mbali imodzi ndipo mawaya amalimbikira mbali inayo. 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.

Ngati pali magawo pa PCB omwe angachotsedwe kapena kubwezeretsedwanso pambuyo popanga, Socket adzagwiritsidwa ntchito kukhazikitsa ziwalozo. 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. Chala chagolide chimakhala ndi mapadi angapo amkuwa omwe alinso mbali ya zingwe za PCB. Nthawi zambiri, kuti tigwirizane, timayika chala chagolide pa PCB imodzi mu Slot yoyenera (yomwe imadziwika kuti Slot yowonjezera) pa PCB inayo. In computers, display cards, sound cards, and similar interface cards are connected to the motherboard by means of a gold finger.

Mtundu wobiriwira kapena wabulauni pa PCB ndi mtundu wa chigoba cha solder. This layer is an insulating shield that protects the copper wire and prevents parts from being welded to the wrong place. Chophimba china cha silika chidzasindikizidwa pa chosanjikiza cha solder. 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

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Mabungwe amtundu umodzi

Monga tidanenera, pa PCB yoyambira, malowa amakhala mbali imodzi ndipo mawaya amayang’ana mbali inayo. Because the wire appears on only one side, we call this TYPE of PCB single-sided. Chifukwa mapanelo amodzi anali ndi zoletsa zambiri pakapangidwe ka dera (chifukwa panali mbali imodzi yokha, kulumikizana sikungadutse ndikuyenera kutenga njira ina), ma circuits oyambilira okha ndiwo amagwiritsa ntchito matabwa amenewo.

Mabungwe azigawo ziwiri

Bungwe loyendetsa dera lili ndi zingwe mbali zonse ziwiri. But in order to use both wires, there must be proper electrical connections between the two sides. “Mlatho” uwu pakati pa madera umatchedwa dzenje lotsogolera (VIA). Mabowo otsogolera ndi mabowo ang’onoang’ono mu PCB yodzazidwa kapena yokutidwa ndi chitsulo chomwe chitha kulumikizidwa ndi mawaya mbali zonse. 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

Pofuna kuwonjezera dera lomwe limatha kulumikizidwa, amagwiritsa ntchito matabwa amodzi kapena awiri. Bolodi yama multilayer imagwiritsa ntchito mapanelo angapo ophatikizika, ndipo osanjikiza amaikidwa pakati pa gulu lililonse ndikumata (chosindikizidwa). 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. Makompyuta akuluakulu ambiri amagwiritsa ntchito ma boardboard angapo, koma agwiritsika ntchito chifukwa amatha kusinthidwa ndi masango amakompyuta wamba. 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.

Part ma CD luso

Kudzera mu 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. Chifukwa chake malumikizidwe awo amatenga malo mbali zonse ziwiri, ndipo zolumikizira za solder ndizazikulu. Kumbali inayi, magawo a THT amalumikizidwa bwino ndi PCB kuposa magawo a Surface Mount Technology (SMT), omwe tikambirane pambuyo pake. 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.

Mbali zomatira zomata zimatha kutenthetsedwa mbali zonse ziwiri.

SMT imakhalanso ndi magawo ang’onoang’ono kuposa 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

Mukupanga kwa PCB, pamakhala masitepe ataliatali kwambiri omwe muyenera kudutsa musanayende waya. Otsatirawa ndi njira yayikulu yopangira:

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

Gawo lotsatira ndikupanga chithunzi chojambulidwa cha dongosololi. Ubale pakati pamabwalo uyeneranso kudziwika.

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.

Sankhani njira yonyamula yomwe ingagwiritsidwe ntchito komanso kukula kwa PCB iliyonse

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. Mtundu ndi liwiro la chithunzithunzi cha dera ziyeneranso kuganiziridwa posankha ukadaulo.

Draw schematic circuit diagrams of all PCB’s

The details of the interconnections between the parts should be shown in the sketch. PCB pamakina onse ayenera kufotokozedwa, ndipo ambiri amagwiritsa ntchito CAD (Computer Aided Design) pakadali pano. Here is an example of a CircuitMakerTM design.

Chojambula cha dera la 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. Ayenera kulumikizidwa ndi njirayo m’njira yabwino kwambiri. 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

Ena mwa mapulogalamu apakompyuta amakono amatha kuwona ngati kusungidwa kwa chinthu chilichonse kumatha kulumikizidwa molondola, kapena kuwunika ngati kungagwire bwino ntchito mwachangu kwambiri. Gawo ili limatchedwa kukonza magawo, koma sitichita izi. Ngati pali vuto ndi kapangidwe ka dera, magawo atha kukonzedwanso dera lisanatumizedwe kumunda.

Tumizani dera pa PCB

The connections in the sketch will now look like wiring in the field. Gawo ili nthawi zambiri limakhala lokwanira, ngakhale pamafunika kusintha pamanja. Below is the wire template for 2 laminates. Mizere wofiira ndi wabuluu akuimira PCB mbali wosanjikiza ndi wosanjikiza kuwotcherera motero. The white text and squares represent the markings on the screen printing surface. Madontho ofiira ndi mabwalo akuyimira kuboola ndi kutsogolera mabowo. Kudzanja lamanja titha kuwona chala chagolide pamalo otsekemera a 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. Mafotokozedwewa amasiyanasiyana kutengera kuthamanga kwa dera, mphamvu ya siginecha yomwe imafunikira, chidwi cha dera kumagwiritsidwe ntchito kwamagetsi ndi phokoso, komanso mtundu wazinthu zopangira ndi zida zopangira. 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. Ngati pakufunika zigawo zopitilira 2, mphamvu yamagetsi ndi yosanjikiza pansi imagwiritsidwa ntchito popewa chizindikiritso chazomwe zikukhudzidwa, ndipo chitha kugwiritsidwa ntchito ngati chishango chazizindikiro.

Wire after circuit test

In order to be sure that the line is working properly behind the wire, it must pass the final test. Kuyesaku kumawunikiranso kulumikizana kolakwika, ndipo kulumikizana konse kumatsata chithunzithunzi.

Khazikitsani ndikujambulitsa

Chifukwa pakadali pano pali zida zambiri za CAD zopanga PCBS, opanga ayenera kukhala ndi mbiri yomwe ikukwaniritsa miyezo asanapange matabwa. 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

Zipangizo zamagetsi zomwe sizinapangidwe kuti zilembedwe ndi EMC mwina zimatulutsa mphamvu zamagetsi ndikumasokoneza zida zapafupi. EMC imakhazikitsa malire pazoyeserera zamagetsi (EMI), gawo lamagetsi yamagetsi (EMF) komanso kusokonekera kwamawayilesi (RFI). Lamuloli limatha kuonetsetsa kuti zida zogwiritsira ntchito ndi zida zina zapafupi zikuyenda bwino. EMC imakhazikitsa malire okhwima pamagetsi omwe amatha kumwazikana kapena kufalikira kuchokera pachida chimodzi kupita china, ndipo adapangidwa kuti achepetse kutengeka ndi ma EMF akunja, EMI, RFI, ndi zina zambiri. 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. Ma EMI amkati, monga kutayika kwaposachedwa pakati pa oyendetsa, kumawonjezeka ndikukula kwakanthawi. Ngati kusiyana komwe kulipo pakati pa ziwirizi ndi kwakukulu kwambiri, onetsetsani kuti mwatalikitsa mtunda pakati pawo. This also tells us how to avoid high voltage and minimize the current consumption of the circuit. Kuchuluka kwa kuchedwa kwa waya ndikofunikanso, chifukwa chake kufupikitsa kutalika, kumakhala bwino. Chifukwa chake PCB yaying’ono yokhala ndi zingwe zabwino imagwira ntchito bwino kwambiri kuposa liwiro lalikulu.