Te poari porowhita i panuitia (PCB) e kitea ana i nga momo taputapu hiko katoa. 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. I runga i te PCB taketake, kei te kaha nga waahanga ki tetahi taha ka huri nga waea ki tetahi taha. 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.

Mena he waahanga kei runga i te PCB ka taea te tango, te whakahoki ranei i muri i te mahinga, ka whakamahia te Socket ki te whakauru i nga waahanga. 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. Kei te maihao koura te maha o nga papa parahi kikii he waahanga no te waea PCB. Te tikanga, ki te hono, ka whakauruhia e tatou te maihao koura ki tetahi PCB ki tetahi Kāniwha tika (e kiia ana ko te Koha Roha) i runga i tetahi atu PCB. In computers, display cards, sound cards, and similar interface cards are connected to the motherboard by means of a gold finger.

Ko te kara kakariki parauri ranei i te PCB te tae o te kanohi kanohi. This layer is an insulating shield that protects the copper wire and prevents parts from being welded to the wrong place. Ka taatahia tetahi atu mata hiraka ki te papa parenga aukati. 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

Poutohu).

Poari taha-takitahi

Ka rite ki ta maatau i korero ai, i runga i te PCB taketake, kei te kaha nga waahanga ki tetahi taha ka huri nga waea ki tetahi taha. Because the wire appears on only one side, we call this TYPE of PCB single-sided. Na te mea kotahi nga hereni i tino kaha te aukati i te hoahoa o te ara iahiko (na te mea kotahi noa te taha, kaore e taea e nga waea waea te whakawhiti, me wehe ke i tetahi atu huarahi), ko nga ara iahiko noa i whakamahia nga papa pera.

Poari taha-takirua

Kei te poari taiawhio nga waea hiko i nga taha e rua. But in order to use both wires, there must be proper electrical connections between the two sides. Ko tenei “piriti” i waenga i nga huringa e kiia ana he poka aratohu (VIA). Ko nga rua aratohu he kohao iti i te PCB kapi kapi ranei i te maitai ka taea te hono atu ki nga waea i nga taha e rua. 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

Kia nui ake ai te waahanga ka taea te waea, kia kotahi ake – kia rua ranei nga papa waea waea e whakamahia ana. He maha nga papanga taarua e whakamahia ana e te papa multilayer, a ka whakauruhia he paparanga kiriweti ki waenga i ia papanga ka piri (ka peehia). 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. Ko te nuinga o nga rorohiko nui e whakamahi ana i etahi papa papaaho, engari kua taka ke atu te whakamahi na te mea ka taea e nga kohinga rorohiko noa te whakakapi. 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.

Hangarau hangarau takai

Na roto i te Hangarau 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. Na ko o raatau hononga ka mau ake i nga waahanga e rua, a he nui te hononga o te reera. I tetahi atu, he pai ake te hono o nga waahanga THT ki te PCB i nga waahanga Hangarau Hangarau Mata (SMT), ka korerohia e taatau i muri mai. 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.

Ko nga waahanga piripiri mata ka taea te paiherea i nga taha e rua.

He iti ake nga waahanga o te SMT i te 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

I roto i te hoahoa PCB, he roa tonu nga huarahi kia haere i mua i nga waea whakahoahoa. E whai ake nei ko te mahinga hoahoa matua:

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

Ko te mahi ka whai ake ko te hanga i tetahi hoahoa poraka mahi o te punaha. Ko te whanaungatanga i waenga i nga tapawha me tohu ano hoki.

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.

Whakatauhia te tikanga takai hei whakamahi me te rahinga o ia 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. Ko te kounga me te tere o te hoahoa ara iahiko me whai whakaaro ki a koe ka kowhiria te hangarau.

Draw schematic circuit diagrams of all PCB’s

The details of the interconnections between the parts should be shown in the sketch. Ko te PCB kei roto i nga punaha katoa me whakaahua, a ko te nuinga kei te whakamahi i te CAD (Hoahoa Awhina Rorohiko) i tenei wa. Here is an example of a CircuitMakerTM design.

Ko te hoahoa Schematic o te ara iahiko 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. Me hono atu raatau ki te huarahi ma te huarahi tino whaihua. 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

Ko etahi o nga raupaparorohiko rorohiko o tenei ra ka taea te tirotiro mena e tika ana te hono o te whakanoho o ia waahanga, te tirotiro mena ka tika te whakahaere i te tere tere. Ko tenei taahiraa e kiia ana ko te whakarite waahanga, engari kaore e roa te waa e uru atu ki tenei. Mena he raru mo te hoahoa ara iahiko, ka taea hoki te whakarereke i nga waahanga i mua i te kaweake o te ara iahiko i te parae.

Kaweake iahiko i runga i te PCB

The connections in the sketch will now look like wiring in the field. Ko tenei taahiraa he tino mahi aunoa, ahakoa he tikanga me whakarereke a-ringa. Below is the wire template for 2 laminates. Ko nga raina whero me te kikorangi e tohu ana i nga waahanga waahanga PCB me te papa whakarewa. The white text and squares represent the markings on the screen printing surface. Ko nga tohu whero me nga porowhita e tohu ana i te keri me te rua arataki. I te taha matau rawa ka kitea te maihao koura i te mata maitai o te 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. Ko enei whakaritenga e rereke ana kia rite ki te tere o te ara iahiko, te kaha o te tohu ki te tuku, te mohio o te ara iahiko ki te kohi hiko me te haruru, me te kounga o nga taonga me nga taputapu hanga. 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. Mena he nui ake i te rua nga waahanga e hiahiatia ana, ko te waahanga hiko me te papa o te whenua ka whakamahia kia kore ai e tukuna te tohu tuku i runga i te tohu tohu ka pangia, ka taea te whakamahi hei whakangungu rakau mo te papa tohu.

Wire after circuit test

In order to be sure that the line is working properly behind the wire, it must pass the final test. Ka tirohia hoki e tenei whakamatautau nga hononga he, ana ko nga hononga katoa e whai ana i te hoahoa kaupapa.

Whakatauhia me te konae

Na te mea he maha nga taputapu CAD i tenei wa mo te hoahoa PCBS, me whai tohu nga kaihanga ki nga paerewa i mua i te mahinga papa. 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

Ko nga taputapu hiko kaore i te hangaia mo nga whakaritenga EMC ka kaha ki te whakaputa i te kaha hiko hiko ka pokanoa ki nga taputapu e tata ana. Ka tohaina e te EMC nga rahinga nui mo te aukatinga electromagnetic (EMI), mara electromagnetic (EMF) me te awangawanga auau irirangi (RFI). This regulation can ensure the normal operation of the appliance and other nearby appliances. Ka tohaina e EMC he tino taumaha mo te kaha e taea ai te marara, te whakawhiti ranei mai i tetahi taputapu ki tetahi atu, a kua hoahoatia hei whakaiti i te awangawanga o waho o EMF, EMI, RFI, aha atu. 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 o roto, penei i te ngaronga o tenei wa i waenga i nga kaiarahi, ka piki ake ka piki haere te auau. Mena he nui rawa te rereketanga o naianei, tirohia me whakaroa te tawhiti i waenga i a raua. This also tells us how to avoid high voltage and minimize the current consumption of the circuit. He mea nui ano te tere whakaroa i nga waea waea, no reira ka poto te roa, ka pai ake. Na ko tetahi PCB iti me nga waea waea pai ka pai ake te tere i te PCB nui.