A cikin ƙirar TC EMC na PCB, damuwa ta farko shine saitin Layer; Yadudduka na jirgi sun haɗa da samar da wutar lantarki, ƙasa da siginar sigina. A cikin ƙirar samfuran EMC, ban da zaɓin abubuwan haɗin gwiwa da ƙirar kewaya, ƙirar PCB mai kyau shima abu ne mai mahimmanci.

The key to the EMC design of PCB is to minimize the backflow area and make the backflow path flow in the direction we designed. Tsarin Layer shine tushen PCB, yadda ake yin kyakkyawan aiki na ƙirar ƙirar PCB don yin tasirin EMC na PCB mafi kyau?

I. Design ideas na PCB Layer

The core of PCB laminated EMC planning and design is to reasonably plan signal backflow path to minimize the backflow area of signal from the board mirror layer, so as to eliminate or minimize magnetic flux.

Single allon mirroring Layer

Layer madubi shine cikakken Layer na jirgin saman da aka rufe da tagulla (Layer samar da wutar lantarki, layin ƙasa) kusa da layin siginar a cikin PCB. Babban ayyukan sune kamar haka:

(1) Rage amo mai juyawa: layin madubi na iya ba da ƙarancin ƙarancin ƙarancin hanya don dawo da layin siginar, musamman lokacin da akwai babban kwarara mai gudana a cikin tsarin rarraba wutar lantarki, rawar madubin madubi ya fi bayyane.

(2) Rage EMI: wanzuwar madubin madubi yana rage yanki na rufaffiyar madauki da siginar da reflux ya samar kuma ya rage EMI;

(3) reduce crosstalk: help to control the crosstalk problem between signal lines in high-speed digital circuit, change the height of the signal line from the mirror layer, you can control the crosstalk between signal lines, the smaller the height, the smaller the crosstalk;

(4) Ikon rashin ƙarfi don hana tunanin siginar.

Selection of mirror layer

(1) Dukansu wutar lantarki da jirgin ƙasa za a iya amfani da su azaman jirgin tunani, kuma suna da wani tasiri na kariya akan wayoyin cikin gida;

(2) Relatively speaking, the power plane has a high characteristic impedance, and there is a large potential difference with the reference level, and the high-frequency interference on the power plane is relatively large;

(3) From the perspective of shielding, the ground plane is generally grounded and used as the reference point of the reference level, and its shielding effect is far better than that of the power plane;

(4) Lokacin zaɓar jirgin tunani, yakamata a fifita jirgin ƙasa, kuma a zaɓi jirgin wutar lantarki na biyu

Two, magnetic flux cancellation principle

Dangane da lissafin Maxwell, duk wani aiki na lantarki da na maganadisu tsakanin sassan jikin da aka caje ko raƙuman ruwa ana watsa su ta tsakiyar yankin da ke tsakanin su, ko injin ne ko mai ƙarfi. In a PCB, the flux is always propagated in the transmission line. If the rf backflow path is parallel to the corresponding signal path, the flux on the backflow path is in the opposite direction to that on the signal path, then they are superimposed on each other, and the effect of flux cancellation is obtained.

Yanayin sokewar magudanar ruwa

Jigon sokewar juyi shine sarrafa hanyar dawo da sigina, kamar yadda aka nuna a zane mai zuwa:

The right hand rule explains the magnetic flux cancellation effect

How to use the right hand rule to explain the magnetic flux cancellation effect when the signal layer is adjacent to the stratum is explained as follows:

(1) Lokacin da igiyar ruwa ke gudana ta cikin waya, za a samar da filin magnetic a kusa da waya, kuma ikon hannun dama yana ƙaddara shugabancin filin magnetic.

(2) lokacin da biyu ke kusa da juna kuma a layi ɗaya da waya, kamar yadda aka nuna a cikin adadi na ƙasa, ɗaya daga cikin madubin wutar lantarki don fitarwa, ɗayan madubin wutar lantarki zai gudana, idan wutar lantarki ta gudana ta cikin waya na yanzu ne kuma siginar dawowar sa na yanzu, to, kishiyar shugabanci biyu na halin yanzu daidai ne, don haka filin su na magnetic daidai ne, amma alkibla tana gaba,Don haka suna soke juna.

Misalai ƙirar katako guda biyar, shida

Don yadudduka shida, an fi son shirin 3

Analysis:

(1) Yayin da siginar siginar ke kusa da jirgin sama mai jujjuyawa, kuma S1, S2 da S3 suna kusa da jirgin ƙasa, an sami mafi kyawun sakamako na sokewar maganadisu. Sabili da haka, S2 shine madaidaicin hanyar juyawa, sannan S3 da S1.

(2) Jirgin wutar yana kusa da jirgin GND, tazara tsakanin jiragen yayi ƙanƙanta sosai, kuma yana da mafi kyawun tasirin sokewar maganadisu da ƙarancin ƙarfin jirgin.

(3) Babban ƙarfin wutan lantarki da zanen bene mai dacewa yana kan layi 4 da 5. Lokacin da aka saita kauri Layer, yakamata a ƙara tazara tsakanin S2-P kuma a rage tazara tsakanin P-G2 (tazara tsakanin Layer Yakamata a rage G1-S2 daidai gwargwado), don rage ƙuntatawar jirgin wutar lantarki da tasirin samar da wutar lantarki akan S2.

Don yadudduka shida, zaɓi 4

Analysis:

Tsarin 4 ya fi dacewa da Tsarin 3 don na gida, ƙaramin adadin buƙatun sigina, wanda zai iya samar da ingantaccen sashin wayoyi S2.

Mummunan tasirin EMC, shirin 2

Tattaunawa: A cikin wannan tsarin, S1 da S2 suna kusa, S3 da S4 suna kusa, kuma S3 da S4 basa kusa da jirgin ƙasa, don haka tasirin sokewar magnetic mara kyau.

ƙarshe

Specific principles of PCB layer design:

(1) There is a complete ground plane (shield) below the component surface and welding surface;

(2) Yi ƙoƙari don gujewa kai tsaye kusa da yadudduka sigina biyu;

(3) Duk siginar siginar suna kusa da jirgin ƙasa gwargwadon iko;

(4) Layer wayoyi na babban mita, saurin gudu, agogo da sauran siginar maɓalli yakamata su sami jirgin ƙasa na kusa.