Mbadamba circuit (PCB) dị na ụdị ngwa elektrọnik ọ bụla. 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 ọkọlọtọ na -ele ihe dị ka nke a. 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. N’elu PCB bụ isi, a na -etinye akụkụ ahụ n’otu akụkụ na wires na -elekwasị anya n’akụkụ nke ọzọ. 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.

Ọ bụrụ na enwere akụkụ dị na PCB nke enwere ike wepu ma ọ bụ tinyeghachi ya mgbe emechara ya, a ga -eji Socket wụnye akụkụ ahụ. 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. Mkpịsị aka ọla edo nwere ọtụtụ mpe mpe akwa ọla kọpa nke bụ n’ezie akụkụ nke wiwi PCB. Dị ka ọ na -adịkarị, iji jikọọ, anyị na -etinye mkpịsị aka ọla edo n’otu PCB n’ime oghere kwesịrị ekwesị (nke a na -akpọkarị oghere mgbasa) na PCB nke ọzọ. In computers, display cards, sound cards, and similar interface cards are connected to the motherboard by means of a gold finger.

Agba akwụkwọ ndụ akwụkwọ ndụ ma ọ bụ agba aja aja na PCB bụ agba nke nkpuchi mkpuchi. This layer is an insulating shield that protects the copper wire and prevents parts from being welded to the wrong place. Ọzọ silk ihuenyo ga -ebipụta na solder eguzogide oyi akwa. 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

Akụkọ Mgbe Ochie).

Ogwe ndị nwere otu akụkụ

Dịka anyị kwuru, na PCB bụ isi, akụkụ ahụ lekwasịrị anya n’otu akụkụ yana wires na -elekwasị anya n’akụkụ nke ọzọ. Because the wire appears on only one side, we call this TYPE of PCB single-sided. N’ihi na otu ogwe nwere ọtụtụ ihe mgbochi siri ike na nhazi nke sekit (n’ihi na enwere naanị otu akụkụ, wiring enweghị ike ịgafe wee were ụzọ dị iche), naanị sekit mbido jiri bọọdụ dị otú ahụ.

Ogwe ndị nwere ihu abụọ

Ogwe sekit nwere wiring n’akụkụ abụọ. But in order to use both wires, there must be proper electrical connections between the two sides. A na -akpọ ” akwa ” a n’etiti sekit ka oghere ntuziaka (VIA). Oghere ntuziaka bụ obere oghere dị na PCB juputara ma ọ bụ jiri ọla kpuchie ya nke enwere ike ijikọ na waya n’akụkụ abụọ. 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

Iji nwekwuo mpaghara enwere ike ijikọ, a na-eji bọọdụ wiring nwere akụkụ abụọ ma ọ bụ abụọ. Ogwe multilayer na -eji ọtụtụ ogwe okpukpu abụọ, a na -etinye akwa mkpuchi n’etiti panel ọ bụla na glued (pịa). 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. Imirikiti nnukwu ndị na -ahụ maka kọmputa na -eji ọtụtụ bọọdụ motherboards, mana ha abaghị uru n’ihi na enwere ike iji ụyọkọ kọmpụta nkịtị dochie ha. 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.

Teknụzụ nkwakọba ihe

Site na teknụzụ Hole

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. Ya mere, nkwonkwo ha na -ewepụta oghere n’akụkụ abụọ ya, na nkwonkwo ịkwa akwa ya pere mpe. N’aka nke ọzọ, akụkụ THT ka ejikọrọ na PCB karịa akụkụ teknụzụ dị n’elu (SMT), nke anyị ga -ekwu maka ya ma emechaa. 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.

Akụkụ nrapado nke elu nwere ike ịgbado ọkụ n’akụkụ abụọ ya.

SMT nwekwara akụkụ pere mpe karịa 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

Na imebe PCB, enwere usoro dị ogologo ga -aga n’ihu tupu ị nweta wiwi nkịtị. Ndị na -esonụ bụ usoro nhazi bụ isi:

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

Nzọụkwụ ọzọ bụ imepụta eserese ngọngọ nke sistemụ. A ga -enwerịrị akara mmekọrịta dị n’ámá.

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.

Kpebie usoro nkwakọ ngwaahịa a ga -eji yana nha PCB ọ bụla

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. Ekwesịrị iburu n’uche ogo na ọsọ nke eserese sekit mgbe ị na -ahọrọ teknụzụ.

Draw schematic circuit diagrams of all PCB’s

The details of the interconnections between the parts should be shown in the sketch. Ekwesịrị ịkọwa PCB na sistemụ niile, ọtụtụ n’ime ha na -ejikwa CAD (Kọmputa Nyere Aka). Here is an example of a CircuitMakerTM design.

Ihe eserese nke PCB circuit

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. Ha ga -ejikọrịrị n’ụzọ ahụ n’ụzọ kacha dị irè. 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

Ụfọdụ ngwanrọ kọmputa nke oge a nwere ike ịlele ma enwere ike ijikọ ntinye nke akụkụ ọ bụla nke ọma, ma ọ bụ lelee ma ọ nwere ike rụọ ọrụ nke ọma na oke ọsọ. A na -akpọ nzọụkwụ a ịhazi akụkụ, mana anyị agaghị agabiga oke na nke a. Ọ bụrụ na enwere nsogbu na nhazi sekit, enwere ike ịhazigharị akụkụ tupu ebupụ sekit n’ọhịa.

Mbupụ mbupụ na PCB

The connections in the sketch will now look like wiring in the field. Nzọụkwụ a na -akpaghị aka na -akpaghị aka, n’agbanyeghị na a na -achọkarị mgbanwe akwụkwọ ntuziaka. Below is the wire template for 2 laminates. Ahịrị na -acha ọbara ọbara na -acha anụnụ anụnụ na -anọchite anya oyi akwa akụkụ PCB na akwa ịgbado ọkụ n’otu n’otu. The white text and squares represent the markings on the screen printing surface. Ihe ntụpọ na okirikiri na -anọchi anya oghere na iduzi ụzọ. N’elu aka nri anyị nwere ike ịhụ mkpịsị aka ọla edo n’elu ebe ịgbado ọkụ nke 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. Nkọwa ndị a na -adịgasị iche dabere na ọsọ nke sekit, ike nke mgbaama a ga -ebugharị, mmetụta nke sekit na oriri ike na mkpọtụ, yana ịdị mma nke akụrụngwa na akụrụngwa nrụpụta. 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. Ọ bụrụ na achọrọ karịa akwa 2, a na -ejikarị ike oyi akwa na ala iji zere mgbaàmà nnyefe na oyi akwa mgbaama na -emetụta, enwere ike iji ya dị ka ọta nke oyi akwa mgbaama.

Wire after circuit test

In order to be sure that the line is working properly behind the wire, it must pass the final test. Nnwale a na -enyochakwa njikọ na -ezighi ezi, na njikọ niile na -eso usoro eserese.

Mepụta na faịlụ

N’ihi na enwere ọtụtụ ngwaọrụ CAD ugbu a maka ịchepụta PCBS, ndị nrụpụta ga -enwerịrị profaịlụ nke na -emezu ụkpụrụ tupu ha arụpụta bọọdụ. 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

Ngwa elektrọnikụ nke emeghị maka nkọwapụta EMC nwere ike ibute ọkụ elektrọnik ma gbochie ngwa ndị dị nso. EMC na -amachi oke nnyonye anya elektrọnik (EMI), mpaghara elektrọnik (EMF) na nnyonye anya ugboro ugboro redio (RFI). Ụkpụrụ a nwere ike hụ na ngwa na ngwa ndị ọzọ dị nso na -arụ ọrụ nke ọma. EMC na -amachibido oke ike nke enwere ike gbasasịa ma ọ bụ bufee site na otu ngwaọrụ gaa na nke ọzọ, ma emebere ya iji belata nhịahụ na EMF, EMI, RFI, na ndị ọzọ. 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 nke ime, dị ka mfu dị ugbu a n’etiti ndị na -eduzi ya, na -abawanye ka ugboro ole na -arị elu. Ọ bụrụ na ọdịiche dị ugbu a n’etiti ha abụọ buru oke ibu, gbaa mbọ gbatịa ogologo n’etiti ha. This also tells us how to avoid high voltage and minimize the current consumption of the circuit. Ọnụego igbu oge na wiring dịkwa mkpa, yabụ na mkpụmkpụ ogologo ya ka mma. Yabụ obere PCB nwere ezigbo wiring ga -arụ ọrụ nke ọma na oke ọsọ karịa nnukwu PCB.