PRINTED CIRCUIT tablo (PCB) yo jwenn nan prèske tout kalite aparèy elektwonik. 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. A standard PCB looks something like this. 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. Sou yon PCB debaz, pati yo konsantre sou yon bò ak fil yo konsantre sou lòt la. 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.

Si gen pati sou PCB la ki ka retire oswa mete tounen sou apre fabrike, yo pral itilize priz pou enstale pati yo. 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. Dwèt an lò gen yon kantite kousinen kwiv fè ki aktyèlman yon pati nan fil elektrik la PCB. Nòmalman, pou konekte, nou mete dwèt lò a sou yon pkb nan plas apwopriye (souvan yo rele ekspansyon plas) sou lòt pkb la. In computers, display cards, sound cards, and similar interface cards are connected to the motherboard by means of a gold finger.

Koulè vèt oswa mawon sou PCB la se koulè mask soude a. This layer is an insulating shield that protects the copper wire and prevents parts from being welded to the wrong place. Yon lòt ekran swa pral enprime sou kouch rezistans soude a. 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

Lejand).

Single-sided Boards

Kòm nou mansyone, sou yon PCB debaz, pati pyès sa yo konsantre sou yon bò ak fil yo konsantre sou lòt la. Because the wire appears on only one side, we call this TYPE of PCB single-sided. Paske panno sèl te gen anpil restriksyon strik sou desen an nan kous la (paske te gen sèlman yon sèl bò, fil elektrik la pa t ‘kapab travèse e yo te pran yon chemen apa), se sèlman sikwi byen bonè itilize tablo sa yo.

Double-sided Boards

Tablo sikwi a gen fil elektrik sou toude bò yo. But in order to use both wires, there must be proper electrical connections between the two sides. Sa a “pon” ant sikwi yo rele yon twou gid (VIA). Twou Gid yo se ti twou nan PCB la plen oswa kouvwi ak metal ki ka konekte nan fil sou tou de bò yo. 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

Yo nan lòd yo ogmante zòn nan ki ka branche, plis sèl – oswa doub-sided tablo fil elektrik yo te itilize. Tablo a multi itilize plizyè panno doub, epi yo mete yon kouch izolasyon ant chak panèl ak kole (bourade). 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. Pifò supercomputers gwo itilize byen yon kouch kèk nan mèr, men yo te tonbe soti nan itilize menm jan yo ka ranplase pa grap nan òdinatè òdinè. 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.

Pati anbalaj teknoloji

Atravè Teknoloji Twou

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. Se konsa, jwenti yo aktyèlman pran espas sou tou de bò yo, ak jwenti yo soude yo relativman gwo. Nan lòt men an, pati THT yo pi byen konekte ak PCB pase andigman monte Teknoloji (SMT) pati, ki nou pral pale sou pita. 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.

Pati adezif andigman ka menm soude sou toude bò yo.

SMT tou te gen pi piti pati pase 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

Nan konsepsyon PCB, gen aktyèlman trè long etap yo ale nan anvan fòmèl fil elektrik. Sa ki anba la a se pwosesis konsepsyon prensipal la:

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

Pwochen etap la se kreye yon dyagram blòk fonksyonèl nan sistèm lan. Relasyon ant kare yo dwe make tou.

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.

Detèmine metòd anbalaj yo dwe itilize ak gwosè chak PCB

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. Bon jan kalite a ak vitès nan dyagram nan sikwi ta dwe tou pran an konsiderasyon lè chwazi teknoloji a.

Draw schematic circuit diagrams of all PCB’s

The details of the interconnections between the parts should be shown in the sketch. PCB nan tout sistèm yo dwe dekri, e pifò nan yo itilize CAD (Computer Aided Design) kounye a. Here is an example of a CircuitMakerTM design.

Dyagram schematic nan sikwi 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. Yo dwe konekte ak chemen an nan fason ki pi efikas. 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

Gen kèk nan lojisyèl òdinatè jodi a ka tcheke si yo ka plasman nan chak eleman dwe kòrèkteman konekte, oswa tcheke si li ka opere kòrèkteman nan gwo vitès. Etap sa a yo rele fè aranjman pou pati, men nou pa pral ale twò lwen nan sa a. Si gen yon pwoblèm ak desen an sikwi, pati kapab tou gen pou rranje anvan yo sikwi a ekspòte nan jaden an.

Ekspòtasyon sikwi sou PCB

The connections in the sketch will now look like wiring in the field. This step is usually fully automated, although manual changes are usually required. Below is the wire template for 2 laminates. Liy wouj ak ble yo reprezante kouch pati PCB ak kouch soude a respektivman. The white text and squares represent the markings on the screen printing surface. Pwen wouj yo ak ti sèk reprezante perçage ak gid twou. Sou bò dwat la byen lwen nou ka wè dwèt an lò sou sifas la soude nan PCB la. 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. Espesifikasyon sa yo varye selon vitès sikwi a, fòs siyal la pou transmèt, sansiblite sikwi a nan konsomasyon pouvwa ak bri, ak kalite materyèl ak ekipman fabrikasyon an. 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. Si yo bezwen plis pase 2 kouch, kouch pouvwa a ak kouch tè yo anjeneral yo itilize pou fè pou evite siyal la transmisyon sou kouch siyal la afekte, epi yo ka itilize kòm yon plak pwotèj nan kouch siyal la.

Wire after circuit test

In order to be sure that the line is working properly behind the wire, it must pass the final test. Tès sa a tou tcheke pou koneksyon kòrèk, ak tout koneksyon swiv dyagram nan schematic.

Etabli epi ranpli

Because there are currently many CAD tools for designing PCBS, manufacturers must have a profile that meets the standards before they can manufacture boards. 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

Aparèy elektwonik ki pa fèt yo espesifikasyon EMC gen chans rive nan emèt enèji elektwomayetik ak entèfere ak aparèy ki tou pre. EMC enpoze limit maksimòm sou entèferans elektwomayetik (EMI), jaden elektwomayetik (EMF) ak entèferans frekans radyo (RFI). This regulation can ensure the normal operation of the appliance and other nearby appliances. EMC enpoze limit strik sou kantite enèji ki ka gaye oswa transmèt soti nan yon aparèy nan yon lòt, epi li fèt pou diminye sansibilite a ekstèn EMF, EMI, RFI, ak sou sa. 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 Entèn, tankou pèt aktyèl ant kondiktè, ogmante kòm frekans lan leve. If the current difference between the two is too large, make sure to lengthen the distance between them. This also tells us how to avoid high voltage and minimize the current consumption of the circuit. Pousantaj reta nan fil elektrik enpòtan tou, kidonk pi kout longè a, pi bon an. Se konsa, yon ti PCB ak fil elektrik bon ap travay pi byen nan gwo vitès pase yon PCB gwo.