Ponena za PCB bolodi, many friends will think that it can be seen everywhere around us, from all household appliances, all kinds of accessories in the computer, to all kinds of digital products, as long as electronic products almost all use PCB board, so what is PCB board? A PCB is a PrintedCircuitBlock, which is a printed circuit board for electronic components to be inserted. A copperplated base plate is printed and etched out of the etching circuit.

Board PCB akhoza kugawidwa mu umodzi wosanjikiza bolodi, wachiphamaso wosanjikiza bolodi ndi bolodi Mipikisano wosanjikiza. Zida zamagetsi zimaphatikizidwa mu PCB. Pa PCB yosanjikiza imodzi, zinthuzo zimayikidwa mbali imodzi ndipo mawaya amayang’ana mbali inayo. Chifukwa chake tifunika kupanga mabowo m’bolodi kuti zikhomo zizitha kudutsa bolodi kupita tsidya lina, kotero zikhomo zazigawo zimalumikizidwa mbali inayo. Because of this, the positive and negative sides of such PCB are respectively called ComponentSide and SolderSide.

A double-layer board can be seen as two single-layer boards glued together, with electronic components and wiring on both sides of the board. Nthawi zina zimakhala zofunikira kulumikiza waya umodzi kuchokera mbali imodzi kupita mbali ina ya bolodi kudzera pa dzenje lowongolera (kudzera). Mabowo otsogolera ndi mabowo ang’onoang’ono mu PCB yodzazidwa kapena yokutidwa ndi chitsulo chomwe chitha kulumikizidwa ndi mawaya mbali zonse. Tsopano ma boardboard amakompyuta ambiri akugwiritsa ntchito zigawo za 4 kapena 6 za bolodi la PCB, pomwe makhadi azithunzi amagwiritsa ntchito zigawo 6 za bolodi la PCB. Makhadi ambiri azithunzi zazitali kwambiri monga nVIDIAGeForce4Ti mndandanda amagwiritsa ntchito zigawo 8 za bolodi la PCB, lomwe limatchedwa bolodi la PCB losanjikiza. The problem of connecting lines between layers is also encountered on multi-layer PCBS, which can also be achieved through guide holes.

Chifukwa ndi PCB yosanjikiza, nthawi zina mabowo owongolera sayenera kulowa mu PCB yonse. Mabowo owongolera oterowo amatchedwa Buriedvias ndi Blindvias chifukwa amangolowa zigawo zochepa. Mabowo akhungu amalumikiza magawo angapo a PCBS amkati mpaka ma PCBS osalowerera bolodi lonse. Mabowo omwe anakwiridwa amalumikizidwa ndi PCB yamkati, kotero kuwala sikuwoneka pamwamba. Mu PCB yama multilayer, gawo lonse limalumikizidwa mwachindunji ndi waya wapansi ndi magetsi. Chifukwa chake timayika zigawozo ngati Signal, Power kapena Ground. Ngati magawo a PCB amafunikira magetsi osiyanasiyana, nthawi zambiri amakhala ndi zigawo zopitilira awiri zamagetsi ndi waya. The more layers you use, the higher the cost. Of course, the use of more layers of PCB board to provide signal stability is very helpful.

The process of making a professional PCB board is quite complicated. Take a 4-layer PCB board for example. The PCB wa bolodi chachikulu makamaka zigawo 4. Mukamapanga, zigawo ziwiri zapakati zimakulungidwa, kudula, kukhazikika, oxidized ndi electroplated motsatana. Zigawo zinayi ndizophatikizika pamwamba, mphamvu yamagetsi, stratum ndi solder lamination motsatana. Zigawo zinayi zimakanikizidwa ndikupanga PCB ya bolodi lalikulu. Then the holes were punched and made. Mukatha kuyeretsa, zigawo ziwiri zakunja za mzere zidasindikizidwa, mkuwa, kutentha, kuyesa, kuwotcherera kosanjikiza, kusindikiza pazenera. Pomaliza, ma PCB onse (kuphatikiza ma boardboard ambiri) amasindikizidwa mu PCB ya bolodi lililonse, kenako ma CD amadzaza mukamaliza mayeso. If the copper skin is not well coated in THE process of PCB production, there will be poor adhesion phenomenon, easy to imply short circuit or capacitance effect (easy to cause interference). The holes on PCB must also be taken care of. If the hole is punched not in the middle, but on one side, it will result in uneven matching or easy contact with the power supply layer or formation in the middle, resulting in potential short-circuiting or bad grounding factors.

Copper wiring process

The first step in fabrication is to establish an online wiring between parts. We use negative transfer to express the working negative on a metal conductor. Chinyengo ndikufalitsa zojambulazo zazitsulo zamkuwa pamwamba pake ndikuchotsa zochulukirapo. Kufunsira kusamutsa ndi njira ina yosagwiritsidwa ntchito, yomwe ndi kugwiritsa ntchito waya wamkuwa pokhapokha ngati pakufunika, koma sitikunena pano.

Positive photoresists are made from photosensitizers that dissolve under illumination. There are many ways to treat photoresist on copper, but the most common way is to heat it and roll it over a surface containing photoresist. It can also be sprayed in liquid form, but the dry film provides higher resolution and allows for thinner wires. Hood ndi template chabe yopanga zigawo za PCB. Chophimba chophimba chithunzi pa PCC chimalepheretsa madera ena a chithunziresist kuti asawonekere mpaka wojambula zithunzi atha kuwunika ndi UV. These areas, which are covered with photoresist, will become wiring. Mbali zina zopanda mkuwa zomwe zimayenera kukhazikitsidwa pambuyo pa chitukuko cha photoresist. The etching process may involve dipping the board into the etching solvent or spraying the solvent onto the board. Amagwiritsidwa ntchito ngati zosungunulira zogwiritsa ntchito mankhwala enaake amchere. After etching, remove the remaining photoresist.

1.Wiring m’lifupi ndi zamakono

General width should not be less than 0.2mm (8mil)

On high density and high precision PCBS, pitch and line width are generally 0.3mm (12mil).

Makulidwe a zojambulazo zamkuwa zili pafupifupi 50um, m’lifupi mwa waya ndi 1 ~ 1.5mm (60mil) = 2A

Zomwe anthu wamba amaganiza nthawi zambiri zimakhala ma 80mil, makamaka pamafunso okhala ndi ma microprocessors.

2.Kodi kuthamanga kwa bolodi yothamanga kwambiri kumakhala kotani?

Kukwera / kugwa kwa nthawi yolengeza “3 ~ 6 nthawi yofalitsa nthawi, imadziwika ngati siginecha yothamanga.

Kwa ma digito ama digito, chinsinsi ndicho kuyang’ana kutsetsereka kwa chizindikirocho, nthawi yomwe imafunika kuti ikwere ndi kugwa,

According to a very classic book “High Speed Digtal Design” theory, the signal from 10% to 90% of the time is less than 6 times the wire delay, is high-speed signal! – – – – – – omwe! Even 8KHz square wave signals, as long as the edges are steep enough, are still high-speed signals, and transmission line theory needs to be used in wiring

3.PCB stacking ndi layering

The four – layer plate has the following stacking sequence. Ubwino ndi zovuta za lamination zosiyanasiyana zafotokozedwa pansipa:

Mlandu woyamba uyenera kukhala wabwino kwambiri pagawo zinayi. Because the outer layer is the stratum, it has a shielding effect on EMI. Meanwhile, the power supply layer is reliable and close to the stratum, which makes the internal resistance of the power supply smaller and achieves the best suburbs. Komabe, vuto loyamba silingagwiritsidwe ntchito ngati kuchuluka kwa bolodi kuli kochuluka. Chifukwa ndiye, umphumphu wa wosanjikiza woyambawo sunatsimikizidwe, ndipo chizindikiro chachiwiri chosanjikiza ndi choyipa. Kuphatikiza apo, kapangidwe kameneka sikangagwiritsidwe ntchito pakugwiritsa ntchito mphamvu zazikulu za gulu lonse.

The second case is the one we usually use the most. Kuchokera pamapangidwe a bolodi, siyoyenera kapangidwe ka digito kothamanga kwambiri. N’zovuta kukhalabe ndi mphamvu yotsika yamagetsi munjira imeneyi. Take a plate 2 mm as an example: Z0=50ohm. To line width of 8mil. Copper foil thickness is 35цm. Chifukwa chake wosanjikiza wazizindikiro ndi pakati pakupanga ndi 0.14mm. The formation and power layer are 1.58mm. This greatly increases the internal resistance of the power supply. In this kind of structure, because the radiation is to the space, shielding plate is needed to reduce EMI.

In the third case, the signal line on layer S1 has the best quality. Zamgululi Kuteteza kwa EMI. But the power supply impedance is large. This board can be used when the power consumption of the whole board is high and the board is an interference source or adjacent to the interference source.

4. Impedance matching

Matalikidwe amtundu wamagetsi owonetsedwa amatsimikiziridwa ndi koyezera koyenera kwa gwero ρ S ndi chiyerekezo chofanizira cha katundu ρL

ρL = (RL-z0)/(RL + Z0) and ρS = (rS-z0)/(RS + Z0)

Muyeso yomwe ili pamwambapa, ngati RL = Z0, choyezera chokwanira chokwanira ρL = 0. Ngati RS = Z0 choyezera chomaliza chofanizira sourceS = 0.

Chifukwa impedance yapaulendo wamba wa Z0 nthawi zambiri imakwaniritsa zofunikira za 50 ω 50 ω, ndipo katundu wa impedance nthawi zambiri amakhala pama ohms masauzande mpaka makumi masauzande a ohms. Chifukwa chake, ndizovuta kuzindikira kutengera kwa impedance mbali yonyamula. Komabe, chifukwa chizindikiritso cha ma source (output) impedance nthawi zambiri chimakhala chaching’ono, pafupifupi makumi a ohms. Chifukwa chake ndizosavuta kukhazikitsa njira zofananira ndi gwero. Ngati cholumikizira chikalumikizidwa kumapeto kwa katunduyo, wotsutsawo angatenge gawo la chizindikirocho kuti chiwonongeko cha kufalitsa (kumvetsetsa kwanga). Pamene TTL / CMOS yoyendetsa 24mA drive ikasankhidwa, kutulutsa kwake kumakhala pafupifupi 13 ω. Ngati mzere wothamangitsira Z0 = 50 ω, ndiye kuti 33-chitsime chomaliza chotsutsana chikuyenera kuwonjezeredwa. 13 ω +33 ω = 46 ω (pafupifupi 50 ω, kuchepa kwanyumba kofooka kumathandizira kukhazikitsa nthawi)

Miyezo ina yotumizira ndi mafunde oyendetsa akasankhidwa, impedance yofananira imatha kukhala yosiyana. Mumalingaliro othamanga kwambiri komanso kapangidwe ka dera, pazizindikiro zina zazikulu, monga wotchi, maulamuliro, tikupangira kuti gwero lofananira ndi gwero liyenera kuwonjezedwa.

Mwanjira iyi, siginecha yolumikizidwa iwonetsedwa kumbuyo kuchokera mbali yonyamula, chifukwa gwero la impedance limayenderana, siginolo yowonetsedwayo siziwonetsedwanso.