Papa kaapuni paʻi (PCB) ʻike ʻia i loko o nā ʻano uila like ʻole. 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. Ma kahi PCB maʻamau, hoʻopili ʻia nā ʻāpana i kekahi ʻaoʻao a hoʻopaʻa ʻia nā kaula i kekahi ʻaoʻao. 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.

Inā he mau ʻāpana ma ka PCB hiki ke hemo a hoʻihoʻi ʻia ma hope o ka hana ʻana, e hoʻohana ʻia ke kumu i mea e hoʻouka ai i nā ʻāpana. 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. Aia i ka manamana gula kahi helu o nā pale keleawe ʻōlohelohe i ʻāpana maoli o nā pilina PCB. ʻO ka maʻamau, e hoʻohui, hoʻokomo mākou i ka manamana gula ma hoʻokahi PCB i kahi Slot kūpono (i kapa ʻia ʻo Slot hoʻonui) ma ka PCB ʻē aʻe. In computers, display cards, sound cards, and similar interface cards are connected to the motherboard by means of a gold finger.

ʻO ke kala ʻōmaʻomaʻo a ʻeleʻele paha ma ka PCB ke kala o ka mask mask. This layer is an insulating shield that protects the copper wire and prevents parts from being welded to the wrong place. E paʻi ʻia kekahi pale silika ma ka ʻāpana kūʻē pae. 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

Legend).

Na Papa pili aoao

E like me kā mākou i ʻōlelo ai, ma kahi PCB maʻamau, hoʻopili ʻia nā ʻāpana i kekahi ʻaoʻao a hoʻopili ʻia nā uea i kekahi ʻaoʻao. Because the wire appears on only one side, we call this TYPE of PCB single-sided. Ma muli o ka nui o nā kapu koʻikoʻi o nā panela hoʻokahi i ka hoʻolālā o ke kaapuni (no ka mea hoʻokahi wale nō ʻaoʻao, ʻaʻole hiki i nā uea ke hele a hele i kahi ala kaʻawale), hoʻohana wale nā ​​kaapuni i kēlā mau papa.

Na Papa aoao-papalua

He uea ka papa kaapuni ma nā ʻaoʻao ʻelua. But in order to use both wires, there must be proper electrical connections between the two sides. Kapa ʻia kēia “alahaka” ma waena o nā kaapuni he puka alakaʻi (VIA). ʻO nā lua alakaʻi he mau puka liʻiliʻi i ka PCB i piha a i uhi ʻia me ka mea hiki ke hoʻopili ʻia i nā kaula ma nā ʻaoʻao ʻelua. 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

I mea e hoʻonui ai i ka wahi i hiki ke hoʻoheheʻe ʻia, ʻoi aku ka mea hoʻokahi – a i ʻole hoʻohana pālua ʻia nā papa uila. Hoʻohana ka papa multilayer i nā panela pālua, a kau ʻia kahi papa o ka hoʻolaulea ma waena o kēlā me kēia panela a kāpili ʻia (kaomi ʻia). 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. Hoʻohana ka hapa nui o nā supercomputers i kekahi mau papa o nā papa makuahine, akā ua hāʻule lākou i waho o ka hoʻohana no ka mea hiki iā lākou ke pani ʻia e nā huhui o nā kamepiula maʻamau. 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.

ʻEnehana ʻāpana ʻāpana

Ma o ʻenehana 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. No laila lawe maoli kā lākou mau hui i ka hakahaka ma nā ʻaoʻao ʻelua, a nui ka ami solder. Ma kekahi ʻaoʻao, ʻoi aku ka pili o nā ʻāpana THT i ka PCB ma mua o nā ʻenehana Surface Mounted Technology (SMT), a mākou e kamaʻilio ai ma hope. 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.

Hiki ke hoʻoheheʻe ʻia nā ʻāpana hoʻopili āpau ma nā ʻaoʻao ʻelua.

Loaʻa nā ʻāpana liʻiliʻi o SMT ma mua o 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 ka hoʻolālā PCB, aia he mau ʻanuʻu lōʻihi loa e hele ma mua o ka hoʻopili pono ʻana. ʻO ka aʻe ka hana hoʻolālā nui:

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

ʻO ka hana hou e hana i kahi kiʻiona poloka hana o ka ʻōnaehana. Pono e māka ka pilina ma waena o nā pāha.

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.

E hoʻoholo i ke ʻano hoʻopili e hoʻohana ai a me ka nui o kēlā me kēia 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. Pono e noʻonoʻo ʻia ka maikaʻi a me ka wikiwiki o ke kiʻikuhi kele i ke koho ʻana i ka ʻenehana.

Draw schematic circuit diagrams of all PCB’s

The details of the interconnections between the parts should be shown in the sketch. Pono e wehewehe ʻia ka PCB ma nā ʻōnaehana āpau, a hoʻohana ka hapanui o lākou iā CAD (Hoʻolālā Kōkua Kōkua) i kēia manawa. Here is an example of a CircuitMakerTM design.

Kiʻikuhi scimika o ka pōʻai ʻo 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. Pono lākou e pili i ke ala i ke ala kūpono loa. 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

Hiki i kekahi o nā polokalamu kamepiula o kēia lā ke nānā inā hiki ke hoʻopili pololei ʻia ke kau ʻana o kēlā me kēia mea, a i ʻole hiki ke hana pololei i ka wikiwiki. Kapa ʻia kēia ʻanuʻu i ka hoʻonohonoho ʻana i nā ʻāpana, akā ʻaʻole mākou e hele lōʻihi i kēia. Inā loaʻa kahi pilikia me ka hoʻolālā kaapuni, hiki i nā ʻāpana ke hoʻoponopono hou ʻia ma mua o ka hoʻokuʻu ʻia ʻana o ka pōʻai i ka mahinaʻai.

E hoʻokuʻu kaapuni ma 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. ʻO nā laina ʻulaʻula a polū hoʻi e hōʻike i nā ʻāpana PCB a me ka papa kuʻihao. The white text and squares represent the markings on the screen printing surface. Hōʻike nā kiko ʻulaʻula a me nā pōʻai i ka ʻeli ʻana a me nā lua alakaʻi. Ma ka ʻaoʻao ʻākau loa hiki iā mākou ke ʻike i ka manamana gula ma ka pae hao o ka 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. Hoʻololi kēia mau kikoʻī e like me ka wikiwiki o ke kaapuni, ka ikaika o ka hōʻailona e lawe ʻia, ka ʻike o ke kaapuni i ka hoʻohana mana a me ka walaʻau, a me ka maikaʻi o nā mea a me nā pono hana. 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. Inā makemake ʻia ma mua o 2 mau papa, hoʻohana pinepine ʻia ka papa mana a me ka papa honua e hōʻalo ai i ka hōʻailona hoʻoili ma ka papa o ka hōʻailona, ​​a hiki ke hoʻohana ʻia ma ke ʻano he pale o ka papa hōʻailona.

Wire after circuit test

In order to be sure that the line is working properly behind the wire, it must pass the final test. Nānā pū kēia hōʻike no nā pilina pololei ʻole, a ʻo nā pilina āpau e ukali i ka kiʻi skema.

Hoʻokumu a faila

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

ʻO nā hāmeʻa uila i hoʻolālā ʻole ʻia i nā kikoʻī EMC e hoʻoili paha i ka ikehu electromagnetic a hoʻopilikia i nā mīkini ma kahi kokoke. Hoʻokomo ʻo EMC i nā palena palena palena ma ka hoʻopili electromagnetic (EMI), kahua electromagnetic (EMF) a me nā alapine alapine (RFI). This regulation can ensure the normal operation of the appliance and other nearby appliances. Hoʻokomo ʻo EMC i nā palena koʻikoʻi ma ka nui o ka ikehu i hiki ke hoʻopuehu a lawe ʻia paha mai kekahi hāmeʻa i kekahi, a ua hoʻolālā ʻia e hōʻemi i ka maʻalahi i ka EMF waho, EMI, RFI, a pēlā aku. 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 kūloko, e like me ka nalowale o kēia wā ma waena o nā alakaʻi, hoʻonui i ka piʻi pinepine ʻana. 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. ʻO ka nui o ka lohi o ka hoʻopili ʻana he mea nui, no laila ke pōkole o ka lōʻihi, ʻoi aku ka maikaʻi. No laila kahi PCB liʻiliʻi me nā uea maikaʻi e hana ʻoi aku ka maikaʻi ma nā wikiwiki kiʻekiʻe ma mua o kahi PCB nui.