With the increasing speed of PCB fanovana signal, ny mpamorona PCB ankehitriny dia mila mahatakatra sy mifehy ny tsy fahafahan’ny PCB soritra. Mifanaraka amin’ny fe-potoana fandefasana famantarana fohy kokoa sy ny tahan’ny famantaranandro avo kokoa amin’ny boriboritany nomerika maoderina, ny fifandraisana PCB dia tsy fifandraisana tsotra intsony, fa ny tsipika fandefasana.

Ahoana ny fomba hifehezana ny impedance PCB

Amin’ny fampiharana, ilaina ny mifehy ny làlan-kizorana rehefa mihoatra ny 1n ny hafainganam-pandeha an-tsokosoko na mihoatra ny 300Mhz ny faharetan’ny analog. Ny iray amin’ireo masontsivana manan-danja amin’ny alàlan’ny PCB dia ny impedance mampiavaka azy (ny tahan’ny herinaratra amin’ny ankehitriny rehefa mandeha ny onja manaraka ny tsipika fampitana signal). The characteristic impedance of wire on printed circuit board is an important index of circuit board design, especially in PCB design of high frequency circuit, it must be considered whether the characteristic impedance of wire is consistent with the characteristic impedance required by device or signal. This involves two concepts: impedance control and impedance matching. This paper focuses on impedance control and lamination design.

Fanaraha-maso Impedance

EImpedance Controling, ny conducteur ao amin’ny board circuit dia hanana ny karazana fampitana signal, mba hanatsarana ny tahan’ny fandefasana ary tokony hampitombo ny fahaizany, raha toa ka ny tsipika noho ny fametahana, ny hatevin’ny fametahana, ny sakan’ny tariby ary ireo anton-javatra hafa, dia hiteraka fiovan’ny sandan’ny impedance, ny fanodikodinan’ny signal. Noho izany, ny sandan’ny impedance an’ny conducteur amin’ny tabilao haingam-pandeha haingam-pandeha dia tokony hofehezina ao anatin’ny faritra iray, fantatra amin’ny anarana hoe “impedance control”.

The impedance of a PCB trace will be determined by its inductive and capacitive inductance, resistance, and conductivity coefficient. Ny antony lehibe manimba ny fisoratan’ny tariby PCB dia ny: ny sakan’ny tariby varahina, ny hatevin’ny tariby varahina, ny tsy fitovizan’ny diélectrika ny medium, ny hatevin’ny medium, ny hatevin’ny pad, ny lalan’ny tariby ambanin’ny tany, ny tariby manodidina ny tariby , sns. Ny impedance PCB dia manomboka amin’ny 25 ka hatramin’ny 120 ohm.

Amin’ny fampiharana, ny tsipika fandefasana PCB mazàna dia misy soritry, sosona iray na maromaro, ary fitaovana insulation. Ny dian-tongotra sy ny sosona dia mamorona ny tsy fitoviana fanaraha-maso. PCBS dia matetika ho maro sosona, ary ny impedance fanaraha-maso dia azo amboarina amin’ny fomba isan-karazany. However, whatever method is used, the impedance value will be determined by its physical structure and the electrical properties of the insulating material:

Ny sakany sy ny hatevin’ny soritry ny famantarana

The height of the core or prefill material on either side of the trace

Fanamboarana ny soritra sy ny lovia

Insulation constants of core and prefilled materials

Ny tsipika fandefasana PCB dia misy endrika roa lehibe: mikraoba sy Stripline.

Microstrip:

Ny tsipika microstrip dia mpitaingin-tsoavaly miaraka amin’ny fiaramanidina fanovozan-kevitra amin’ny lafiny iray ihany, miaraka amin’ny tampony sy ny sisiny miharihary amin’ny rivotra (na mifono), ambonin’ilay faritra misy ny insulateur eran’ny board circuit Er, miaraka amin’ny herinaratra na ny grounding ho referansa. Araka ny aseho etsy ambany:

Fanamarihana: Amin’ny famokarana PCB tena izy, matetika ny mpanamboatra birao dia mitafy ny ambonin’ny PCB amin’ny sosona menaka maitso, noho izany amin’ny fikajiana impedance, ny maodely aseho etsy ambany dia mazàna ampiasaina amin’ny fikajiana tsipika microstrip ambonimbony:

Tsipika:

Ny tsipika kofehy dia kofehy tariby apetraka eo anelanelan’ny fiaramanidina roa, toy ny aseho amin’ny sary etsy ambany. Ny diera elektrika ao amin’ny diélectric izay soloin’ny H1 sy H2 dia mety ho hafa.

The above two examples are only a typical demonstration of microstrip lines and ribbon lines. There are many kinds of specific microstrip lines and ribbon lines, such as coated microstrip lines, which are related to the specific laminated structure of PCB.

The equations used to calculate the characteristic impedances require complex mathematical calculations, usually using field solving methods, including boundary element analysis, so using the specialized impedance calculation software SI9000, all we need to do is control the parameters of the characteristic impedances:

Diélectric tsy miova Er, ny sakany tariby W1, W2 (trapezoid), ny hatevin’ny tariby T ary ny hatevin’ny sosona H.

W1, W2:

The calculated value must be within the red box. Ary dia toy izany koa.

Ny SI9000 dia ampiasaina hanisana raha toa ka feno ny fepetra takiana amin’ny fanaraha-maso impedance:

Diniho aloha ny fifehezana impedance tokana an’ny tsipika data DDR:

TOP layer: hatevin’ny varahina 0.5oz, 5MIL ny sakany, 3.8mil ny halaviran’ny fiaramanidina fanovozan-kevitra, diélectric maharitra 4.2. Safidio ny maodely, soloo ireo masontsivana, ary safidio ny fikajiana Lossless, araka ny hita eo amin’ny sary:

Ny CoaTIng dia midika hoe coaTIng, ary raha tsy misy coaTIng, fenoy 0 ny hateviny ary 1 amin’ny diélectric (diélectric Constant) (rivotra).

Ny substrate dia miorina amin’ny sosona substrate, izany hoe, layer diélectrique, amin’ny ankapobeny mampiasa fr-4, ny hatevin’ny kajy amin’ny rindrambaiko fikajiana impedance, ny diélectric maharitra 4.2 (matetika ambany 1GHz).

Click on Weight (oz) to set the thickness of the copper layer, which determines the thickness of the cable.

9. Hevitra prepreg / fototra momba ny sosona insulate:

PP (Prepreg) dia karazan-fitaovana diélectrique, misy fibre vera sy epoxy resin. Core dia TYPE of medium PP, fa ny sisiny roa kosa rakotra foil varahina, fa ny PP kosa tsy. Rehefa manao takelaka multilayer dia matetika ampiasaina ny core sy PP ary ny PP dia ampifamatorana eo anelanelan’ny ivo sy ny fotony.

10. Ireo raharaha mila fiheverana amin’ny famolavolana lamination PCB

(1) olan’ny ady

Ny famolavolana sosona PCB dia tokony ho simetrika, izany hoe ny hatevin’ny sosona antonony sy ny varahina isaky ny sosona tsirairay dia tokony ho simetrika. Raiso ny sosona enina ohatra, ny hatevin’ny medium-top GND sy ny hery ambany dia tokony hifanaraka amin’ny hatevin’ny varahina, ARY ny an’ny medium GND-L2 sy L3-POWER dia tokony hifanaraka amin’ny hatevin’ny varahina. Tsy hikorontana izany rehefa misakafo.

(2) Ny sosona famantarana dia tokony ampifangaroina miaraka amin’ny fiaramanidina mifanila mifanila aminy (izany hoe, ny hatevin’ny antonony eo anelanelan’ny mari-pamantarana sy ny sosona fametahana varahina mifanila dia tokony ho kely); Ny fitafiana varahina mahery sy ny fitafiana varahina vita amin’ny tany dia tokony hampifangaroina mafy.

(3) Raha misy hafainganam-pandeha haingam-pandeha dia azo ampiana sosona fanampiny hanasaraka ny sosona famantarana, saingy ampirisihina tsy hanokana elanelam-pahefana marobe, izay mety hiteraka fanelingelenana amin’ny feo tsy ilaina.

(4) Ny fizarana sosona famolavolana laminated dia aseho amin’ity tabilao manaraka ity:

(5) Fitsipika ankapobeny momba ny fametrahana ny sosona:

Eo ambanin’ilay faritra misy ny singa (ny sosona faharoa) dia ny fiaramanidina an-tany, izay manome ny sosona miaro ny fitaovana sy ny fiaramanidina fanondroana ho an’ny tariby sosona ambony;

Ny sosona famantarana rehetra dia mifanila amin’ny fiaramanidina ambanin’ny tany araka izay tratra.

Aza atao mifanakaiky mivantana eo anelanelan’ny takelaka famantarana roa araka izay tratra;

Ny famatsiana herinaratra lehibe dia tokony ho mifanila araka izay tratra;

Ny simetran’ny firafitry ny laminate dia raisina.

For the layer layout of the motherboard, it is difficult for the existing motherboard to control the parallel long-distance wiring, and the working frequency of the board level is above 50MHZ

(Ho an’ireo toe-javatra ambanin’ny 50MHZ, azafady mba jereo izy io ary alatsaho tsara araka ny tokony ho izy), ny toro lalana momba ny fametrahana:

Ny haben’ny sehatra sy ny fantsom-bozaka dia ny fiaramanidina (ampinga);

Tsy misy sosona mifampitohy mifanila aminy;

Ny sosona famantarana rehetra dia mifanila amin’ny fiaramanidina ambanin’ny tany araka izay tratra.

Ny famantarana lehibe dia mifanila amin’ny fiforonany ary tsy miampita ny faritra fizarana.