Pamene ma frequency apamwamba / mawayilesi a mawayilesi a microwave amadyetsedwa mu PCB dera, kutayika komwe kumachitika chifukwa cha dera lokha komanso zinthu zozungulira zidzatulutsa kutentha kwina. Kutayika kwakukulu, kumapangitsanso mphamvu yodutsa muzinthu za PCB, komanso kutentha kwakukulu komwe kumapangidwa. Pamene kutentha kwa ntchito ya dera kumaposa mtengo wovotera, dera lingayambitse mavuto. Mwachitsanzo, mmene ntchito chizindikiro MOT, amene amadziwika PCBs, ndi pazipita ntchito kutentha. Pamene kutentha ntchito kuposa MOT, ntchito ndi kudalirika kwa dera PCB adzakhala pangozi. Kupyolera mu kuphatikizika kwa ma electromagnetic modelling ndi kuyeza koyesera, kumvetsetsa mawonekedwe amafuta a RF microwave PCBs kungathandize kupewa kuwonongeka kwa magwiridwe antchito komanso kudalirika komwe kumachitika chifukwa cha kutentha kwambiri.

Kumvetsetsa momwe kutayika kwa kuyika kumachitika m’magawo ozungulira kumathandiza kufotokozera bwino zinthu zofunika zokhudzana ndi kutentha kwa ma frequency apamwamba a PCB. Nkhaniyi idzatenga gawo la microstrip transmission line circuit monga chitsanzo kuti tikambirane za malonda okhudzana ndi kutentha kwa dera. M’dera la microstrip lomwe lili ndi mbali ziwiri za PCB, zotayika zimaphatikizapo kutayika kwa dielectric, kutayika kwa conductor, kutayika kwa ma radiation, ndi kutaya kutayikira. Kusiyana pakati pa zigawo zosiyana zotayika ndi zazikulu. Kupatulapo pang’ono, kutayikira kwa ma frequency apamwamba a PCB nthawi zambiri kumakhala kotsika kwambiri. M’nkhaniyi, popeza mtengo wotayika wotayika ndi wotsika kwambiri, udzanyalanyazidwa panthawiyi.

Kutaya kwa radiation

Kutayika kwa ma radiation kumadalira magawo ambiri ozungulira monga ma frequency ogwiritsira ntchito, makulidwe a gawo lapansi, PCB dielectric constant (wabale dielectric constant kapena εr) ndi dongosolo la mapangidwe. Pankhani yamapangidwe amachitidwe, kutayika kwa ma radiation nthawi zambiri kumabwera chifukwa cha kusasinthika kwapang’onopang’ono kozungulira kapena kusiyana kwa ma electromagnetic wave transmission mudera. Dera losinthira circuit impedance nthawi zambiri limaphatikizapo malo odyetserako ma sign, step impedance point, stub ndi network yofananira. Kukonzekera koyenera kozungulira kumatha kuzindikira kusintha kosalala kwa impedance, motero kumachepetsa kutayika kwa ma radiation a dera. Zachidziwikire, ziyenera kuzindikirika kuti pali kuthekera kwa kusagwirizana kwa impedance komwe kumabweretsa kutayika kwa ma radiation pamawonekedwe aliwonse adera. Kuchokera pamawonekedwe a ma frequency ogwiritsira ntchito, nthawi zambiri amakhala okwera kwambiri, amataya kwambiri ma radiation ozungulira.

Magawo azinthu zamagawo okhudzana ndi kutayika kwa ma radiation nthawi zambiri amakhala dielectric osasintha komanso makulidwe azinthu za PCB. Kukhuthala kwa gawo lapansi, kumapangitsanso mwayi wopangitsa kuti ma radiation awonongeke; kutsika kwa εr kwa zinthu za PCB, kumapangitsa kuti ma radiation awonongeke kwambiri. Kuyeza mozama zakuthupi, kugwiritsa ntchito magawo ocheperako atha kugwiritsidwa ntchito ngati njira yothanirana ndi kutayika kwa ma radiation komwe kumayambitsidwa ndi zida zotsika za εr. Mphamvu ya makulidwe a gawo lapansi ndi εr pakutayika kwa ma radiation ndi chifukwa ndi ntchito yodalira pafupipafupi. Pamene makulidwe a gawo lapansi lozungulira sadutsa 20mil ndipo ma frequency ogwiritsira ntchito ndi otsika kuposa 20GHz, kutayika kwa ma radiation kumachepa kwambiri. Popeza kuti ma frequency ambiri oyendera mayendedwe ndi kuyeza m’nkhaniyi ndi otsika kuposa 20GHz, zokambirana zomwe zili m’nkhaniyi sizinyalanyaza chikoka cha kutayika kwa ma radiation pa kutentha kwa dera.

After ignoring the radiation loss below 20GHz, the insertion loss of a microstrip transmission line circuit mainly includes two parts: dielectric loss and conductor loss. The proportion of the two mainly depends on the thickness of the circuit substrate. For thinner substrates, conductor loss is the main component. For many reasons, it is generally difficult to accurately predict conductor loss. For example, the surface roughness of a conductor has a huge influence on the transmission characteristics of electromagnetic waves. The surface roughness of copper foil will not only change the electromagnetic wave propagation constant of the microstrip circuit, but also increase the conductor loss of the circuit. Due to the skin effect, the influence of copper foil roughness on conductor loss is also frequency-dependent. Figure 1 compares the insertion loss of 50 ohm microstrip transmission line circuits based on different PCB thicknesses, which are 6.6 mils and 10 mils, respectively

Zotsatira zoyezedwa komanso zoyeserera

Mpendero mu Chithunzi 1 uli ndi zotsatira zoyezedwa ndi zotsatira zofananira. Zotsatira zoyeserera zimapezedwa pogwiritsa ntchito pulogalamu yowerengera ya Rogers Corporation ya MWI-2010 microwave impedance. Pulogalamu ya MWI-2010 imagwira mawu ma analytical equations mu mapepala apamwamba pankhani ya microstrip line modelling. Deta yoyesera mu Chithunzi 1 imapezedwa ndi njira yoyezera kutalika kwa ma vector network analyzer. Zitha kuwonedwa kuchokera ku Mkuyu 1 kuti zotsatira zofananira za poto yowonongeka kwenikweni zimagwirizana ndi zotsatira zoyezedwa. Zitha kuwoneka kuchokera pachithunzichi kuti kutayika kwa kondakitala kwa dera locheperako (mapindikira kumanzere akufanana ndi makulidwe a 6.6 mil) ndiye chigawo chachikulu cha kutayika kwathunthu. Pamene makulidwe a dera akuwonjezeka ( makulidwe ofanana ndi mapindikira kumanja ndi 10mil), kutayika kwa dielectric ndi kutaya kwa conductor kumayandikira, ndipo ziwirizo zimapanga kutaya kwathunthu.

Chitsanzo chofananira mu Chithunzi 1 ndi magawo azinthu zamagawo omwe amagwiritsidwa ntchito mudera lenileni ndi: dielectric constant 3.66, loss factor 0.0037, ndi copper conductor surface roughness 2.8 um RMS. Pamene kuuma kwapamwamba kwa zojambulazo zamkuwa pansi pazitsulo zomwezo zimachepetsedwa, kutayika kwa conductor kwa maulendo a 6.6 mil ndi 10 mil mu Chithunzi 1 kudzachepetsedwa kwambiri; komabe, zotsatira zake sizodziwikiratu kwa dera la 20 mil. Chithunzi 2 chikuwonetsa zotsatira za mayeso a zida ziwiri zozungulira zomwe zili ndi roughness yosiyana, zomwe ndi Rogers RO4350B ™ zinthu zozungulira zokhala ndi roughness kwambiri ndi Rogers RO4350B LoPro™ zozungulira zokhala ndi roughness yochepa.

Monga momwe tawonetsera pa Chithunzi 1 ndi Chithunzi 2, kucheperachepera kwa gawo lachigawo, kumapangitsa kuti kutayika kwa kuyika kwa dera kukhale kokwera. Izi zikutanthauza kuti dera likadyetsedwa ndi mphamvu zina za RF microwave mphamvu, dera locheperako limatulutsa kutentha kwambiri. Poganizira mozama nkhani ya kutentha kwa dera, mbali imodzi, dera locheperako limatulutsa kutentha kwambiri kuposa dera lokhuthala lomwe lili ndi mphamvu zambiri, koma kumbali ina, dera locheperako limatha kupeza kutentha kwabwino kwambiri kudzera mumadzi otentha. Sungani kutentha pang’ono.

Pofuna kuthetsa vuto la kutentha kwa dera, dera lochepetsetsa loyenera liyenera kukhala ndi makhalidwe awa: kutayika kochepa kwa zinthu zozungulira, mkuwa wosalala wonyezimira, otsika εr ndi matenthedwe apamwamba. Poyerekeza ndi zinthu zadera za mkulu εr, kondakitala m’lifupi wa impedance yemweyo wopezedwa pansi chikhalidwe otsika εr akhoza kukhala lalikulu, amene n’kopindulitsa kuchepetsa wochititsa imfa ya dera. Kuchokera pamalingaliro a kutentha kwa dera, ngakhale kuti zigawo zambiri za PCB zapafupipafupi zimakhala ndi matenthedwe otsika kwambiri okhudzana ndi ma conductor, matenthedwe azinthu zamagetsi akadali chinthu chofunikira kwambiri.

Zokambirana zambiri zokhuza kutentha kwa magawo ozungulira zidafotokozedwa m’nkhani zam’mbuyomu, ndipo nkhaniyi ifotokoza zotsatira ndi zidziwitso kuchokera m’nkhani zam’mbuyomu. Mwachitsanzo, equation yotsatirayi ndi Chithunzi 3 ndizothandiza kumvetsetsa zinthu zokhudzana ndi kutentha kwa zipangizo zamagetsi za PCB. Mu equation, k ndi kutentha kwa matenthedwe (W / m / K), A ndi malo, TH ndi kutentha kwa gwero la kutentha, TC ndi kutentha kwa gwero lozizira, ndi L ndi mtunda pakati pa gwero la kutentha ndi gwero lozizira.