With the increasing speed of PCB kusinthana kwa siginecha, opanga ma PCB amakono akuyenera kumvetsetsa ndikuwongolera kusokonekera kwa zotsatira za PCB. Yofanana ndi nthawi yayifupi yotumizira ma siginecha komanso mawotchi apamwamba amakono azamagetsi amakono, ma PCB sakulumikizananso, koma mizere yotumiza.

Momwe mungayang’anire kuyimitsidwa kwa PCB

Mwakuchita, ndikofunikira kuwongolera kutsata kwa impedance pomwe liwiro lakumapeto kwa digito limadutsa 1ns kapena mafupipafupi a analog kuposa 300Mhz. Chimodzi mwamagawo ofunikira a PCB ndi kutulutsa kwake kwamphamvu (kuchuluka kwa mphamvu yamagetsi mpaka pano pamene funde likuyenda pamzere wopatsira ma siginolo). 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.

Kuletsa kuyimitsa

EImpedance Controling, wochititsa mu board board azikhala ndi mitundu yonse yamayendedwe, kuti athe kusintha kufalikira ndipo akuyenera kukulitsa pafupipafupi, ngati mzere wokha chifukwa chokhazikika, kukula kwa makulidwe, utali wa waya ndi zinthu zina zosiyanasiyana, zimayambitsa kusintha kwa mtengo wama impedance, kusokoneza kwa siginolo. Chifukwa chake, kufunika kwa impedance kwa wochititsa pa bolodi yothamanga kwambiri kuyenera kuyang’aniridwa pamtundu wina, wotchedwa “impedance control”.

The impedance of a PCB trace will be determined by its inductive and capacitive inductance, resistance, and conductivity coefficient. Zinthu zazikulu zomwe zimakhudza kupindika kwa zingwe za PCB ndi izi: kukula kwa waya wamkuwa, makulidwe amkuwa amkuwa, mawonekedwe a dielectric apakatikati, makulidwe apakatikati, makulidwe a pad, njira ya waya wapansi, zingwe zoyandikana ndi zingwe , etc. Kuyimitsa kwa PCB kumayambira 25 mpaka 120 ohm.

Pochita, chingwe chotumizira cha PCB nthawi zambiri chimakhala ndi tsatanetsatane, gawo limodzi kapena angapo owerengera, ndi zida zotsekera. Zotsatira ndi zigawo zimapanga impedance yolamulira. PCBS nthawi zambiri imakhala yopyapyala, ndipo ma impedance owongolera amatha kumangidwa m’njira zosiyanasiyana. However, whatever method is used, the impedance value will be determined by its physical structure and the electrical properties of the insulating material:

M’lifupi ndi makulidwe a kufufuza

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

Kukhazikitsa kwa kufufuza ndi mbale

Insulation constants of core and prefilled materials

Mizere yotumizira ya PCB imabwera m’njira ziwiri zazikulu: Microstrip ndi Stripline.

Microstrip:

Chingwe cha microstrip ndi chojambulira chokhala ndi ndege yolozera mbali imodzi yokha, kumtunda ndi mbali zake zikuwululidwa ndi mpweya (kapena wokutidwa), pamwamba pa kutchinjiriza kosalekeza komiti yoyang’anira ya Er, ndimagetsi kapena poyikira. Monga tawonetsera pansipa:

Chidziwitso: Pakapangidwe ka PCB weniweni, wopanga bolodi nthawi zambiri amavala pamwamba pa PCB ndi mafuta obiriwira, chifukwa chake pakuwerengera kwa impedance, mtundu womwe ukuwonetsedwa pansipa umagwiritsidwa ntchito pakuwerengera mzere wama microstrip:

Mzere:

Mzere wa riboni ndi nthiti ya waya yomwe imayikidwa pakati pa ndege ziwiri, monga zikuwonetsedwa pachithunzipa. Makina opangira ma dielectric oyimiridwa ndi H1 ndi H2 atha kukhala osiyana.

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:

Dielectric mosalekeza Er, wiring m’lifupi W1, W2 (trapezoid), Kulumikizana makulidwe T ndi kutchinjiriza wosanjikiza makulidwe H.

W1, W2:

The calculated value must be within the red box. Ndi zina zotero.

SI9000 imagwiritsidwa ntchito kuwerengera ngati zofunikira pakuwongolera ma impedance zakwaniritsidwa:

Choyamba werengani malire amtundu umodzi wamtundu wa DDR:

TOP wosanjikiza: 0.5oz makulidwe amkuwa, 5MIL waya m’lifupi, 3.8mil mtunda kuchokera pakuyang’ana ndege, ma dielectric okhazikika 4.2. Sankhani mtunduwo, m’malo mwa magawo, ndikusankha Kuwerengera Kosawerengeka, monga zikuwonetsedwa pachithunzichi:

CoaTIng amatanthauza coaTIng, ndipo ngati palibe coaTIng, lembani 0 makulidwe ndi 1 mu dielectric (dielectric constant) (mpweya).

Gawo lapansi likuyimira gawo lapansi, ndiye kuti, ma dielectric wosanjikiza, omwe amagwiritsidwa ntchito kwambiri ndi fr-4, makulidwe owerengedwa ndi pulogalamu yowerengera ya impedance, ma dielectric okhazikika 4.2 (pafupipafupi ochepera 1GHz).

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

9. Prepreg / Kore lingaliro la kutchinjiriza wosanjikiza:

PP (Prepreg) ndi mtundu wazinthu zopangira ma dielectric, zopangidwa ndi fiber fiber ndi epoxy resin. Core kwenikweni ndi TYPE ya PP sing’anga, koma mbali zake zonse ndizophimbidwa ndi zojambulazo zamkuwa, pomwe PP siyiri. Popanga matabwa multilayer, pakati ndi PP nthawi zambiri zimagwiritsidwa ntchito limodzi, ndipo PP imagwiritsidwa ntchito kulumikizana pakati pachimake ndi pachimake.

10. Zinthu zofunika chidwi mu kapangidwe ka PCB lamination

(1) Vuto la warpage

Kamangidwe wosanjikiza PCB ayenera symmetrical, ndiye kuti, makulidwe a wosanjikiza sing’anga ndi wosanjikiza mkuwa wa wosanjikiza aliyense ayenera kukhala ofananira. Tengani zigawo zisanu ndi chimodzi mwachitsanzo, makulidwe a top-GND ndi mphamvu yapansi-mphamvu iyenera kukhala yogwirizana ndi makulidwe amkuwa, NDI ya GND-L2 ndi L3-POWER sing’anga iyenera kukhala yogwirizana ndi makulidwe amkuwa. Izi sizingagwedezeke popaka laminate.

(2) Chizindikiro chachizindikiro chiyenera kulumikizidwa molumikizana ndi ndege yoyandikana nayo (ndiye kuti, makulidwe apakati pakati pazizindikiro zazingwe ndi yoyandikana ndi yoyala yamkuwa iyenera kukhala yaying’ono kwambiri); Mavalidwe amkuwa amkuwa ndi zokutira zamkuwa ziyenera kulumikizidwa molimba.

(3) Pankhani yothamanga kwambiri, zigawo zowonjezera zimatha kuwonjezeredwa kuti zilekanitse chizindikiro, koma tikulimbikitsidwa kuti tisatenge mphamvu zamagetsi zingapo, zomwe zingayambitse phokoso losafunikira.

(4) Kugawidwa kwa mapangidwe amtundu wa laminated kumawonetsedwa patebulo lotsatirali:

(5) Mfundo zazikuluzikulu zosanjikiza:

Pansi pa chigawo chapamwamba (gawo lachiwiri) pali ndege yapansi, yomwe imapereka chida chotetezera ndi ndege yolozera pazolumikizira pamwamba;

Magawo onse azizindikiro ali pafupi ndi ndege yapansi momwe angathere.

Pewani kulumikizana molunjika pakati pa zigawo ziwiri za sigine momwe mungathere;

Mphamvu yamagetsi iyenera kukhala yoyandikira kwambiri;

Zofanana za kapangidwe ka laminate zimaganiziridwa.

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

(Pazomwe zili pansipa 50MHZ, chonde lembani pamenepo kuti mupumule moyenerera), mfundo yamalingaliro akuti:

Pamwamba pa gawo ndi mawonekedwe owotcherera ndi ndege yathunthu (chishango);

Palibe choyandikana ndi waya wofanana;

Magawo onse azizindikiro ali pafupi ndi ndege yapansi momwe angathere.

Chizindikiro chachinsinsi chili pafupi ndi mapangidwe ndipo sichidutsa gawo logawanika.