Lokacin da aka ciyar da siginar mitar rediyo mai girma/microwave cikin PCB da’ira, asarar da kewayen kanta da kayan da’ira ke haifarwa ba makawa za su haifar da wani adadin zafi. Mafi girman hasara, mafi girman ƙarfin da ke wucewa ta cikin kayan PCB, kuma mafi girman zafi da aka haifar. Lokacin da zafin aiki na kewayawa ya wuce ƙimar ƙima, kewayawa na iya haifar da wasu matsaloli. Misali, sigar aiki na yau da kullun MOT, wanda sananne ne a cikin PCBs, shine matsakaicin zafin aiki. Lokacin da zafin jiki na aiki ya wuce MOT, aiki da amincin da’irar PCB za a yi barazanar. Ta hanyar haɗin ƙirar ƙirar lantarki da ma’aunin gwaji, fahimtar halaye na thermal na RF microwave PCBs na iya taimakawa wajen guje wa lalata ayyukan da’ira da lalata amincin da ke haifar da yanayin zafi.

Fahimtar yadda asarar sakawa ke faruwa a cikin kayan kewayawa yana taimakawa mafi kyawun kwatanta mahimman abubuwan da ke da alaƙa da aikin zafi na da’irori na PCB masu tsayi. Wannan labarin zai ɗauki da’irar layin watsawar microstrip a matsayin misali don tattaunawa game da cinikin da ke da alaƙa da aikin zafi na kewaye. A cikin da’irar microstrip tare da tsarin PCB mai gefe biyu, asara sun haɗa da asarar dielectric, asarar madugu, asarar radiation, da asarar yatsa. Bambanci tsakanin nau’ikan asara daban-daban yana da girma. Tare da ƴan kaɗan, asarar ɗigogi na manyan da’irori na PCB gabaɗaya yayi ƙasa sosai. A cikin wannan labarin, tun da ƙimar hasara mai raguwa ya ragu sosai, za a yi watsi da shi na ɗan lokaci.

Asarar radiyo

Radiation hasara dogara da yawa kewaye sigogi kamar aiki mita, kewaye substrate kauri, PCB dielectric akai (dangi dielectric akai ko εr) da kuma zane shirin. Dangane da tsare-tsaren ƙira, asarar radiation sau da yawa yakan samo asali ne daga mummunan canji na impedance a cikin kewaye ko bambance-bambancen watsawar igiyoyin lantarki a cikin kewaye. Wurin jujjuyawa impedance yawanci ya haɗa da yankin ciyarwar sigina, madaidaicin mataki, stub da cibiyar sadarwa mai dacewa. Ƙirar da’ira mai ma’ana na iya gane canjin impedance mai santsi, don haka rage asarar da’irar. Tabbas, ya kamata a gane cewa akwai yiwuwar rashin daidaituwa na impedance wanda zai haifar da asarar radiation a kowane nau’i na kewaye. Daga ra’ayi na mitar aiki, yawanci mafi girma mita, mafi girma asarar radiation na kewaye.

Ma’auni na kayan kewayawa masu alaƙa da asarar radiation sune galibi dielectric akai-akai da kauri na kayan PCB. Mafi girman ma’aunin kewayawa, mafi girman yiwuwar haifar da asarar radiation; ƙananan εr na kayan PCB, mafi girma asarar radiation na kewaye. Cikakken auna sifofin kayan abu, ana iya amfani da amfani da na’urori na bakin ciki a matsayin hanyar da za a kashe asarar radiation ta hanyar ƙananan kayan kewayawa. Tasirin kauri mai kauri da εr akan asarar hasken kewayawa shine saboda aiki ne mai dogaro da mitar. Lokacin da kauri na da’ira ba ta wuce mil 20 ba kuma mitar aiki ta ƙasa da 20GHz, asarar da’irar ta yi ƙasa sosai. Tunda yawancin ƙirar da’irar da mitocin aunawa a cikin wannan labarin sun kasance ƙasa da 20GHz, tattaunawa a cikin wannan labarin za ta yi watsi da tasirin hasarar radiation akan dumama da’ira.

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

Sakamakon da aka auna da kwaikwayi

Lanƙwasa a cikin Hoto 1 ya ƙunshi sakamakon da aka auna da sakamakon kwaikwayo. Ana samun sakamakon simintin ta amfani da software na lissafin impedance na microwave MWI-2010 na Rogers Corporation. Software na MWI-2010 yana faɗin ma’auni na nazari a cikin takardun gargajiya a fagen ƙirar layin microstrip. Bayanan gwajin da ke cikin Hoto 1 ana samun su ta hanyar bambancin tsayin tsayin mai nazarin hanyar sadarwa na vector. Ana iya gani daga siffa 1 cewa sakamakon kwaikwayo na jimlar asarar hasara sun kasance daidai da sakamakon da aka auna. Ana iya gani daga adadi cewa asarar mai gudanarwa na da’irar bakin ciki (madaidaicin gefen hagu yayi daidai da kauri na 6.6 mil) shine babban ɓangaren asarar shigarwa. Yayin da kauri na kewaye ya karu (kaurin da ke daidai da lankwasa a hannun dama shine 10mil), asarar dielectric da asarar madugu suna zuwa gabatowa, kuma su biyun tare sun zama asarar shigar gabaɗaya.

Samfurin simintin gyare-gyare a cikin Hoto 1 da sigogin kayan da’irar da aka yi amfani da su a cikin ainihin kewaye sune: dielectric akai-akai 3.66, hasara factor 0.0037, da kuma jan karfe saman roughness 2.8 um RMS. Lokacin da aka rage girman fuskar tagulla a ƙarƙashin kayan da’irar guda ɗaya, asarar mai gudanarwa na 6.6 mil da 10 mil da’irori a cikin Hoto 1 za a ragu sosai; duk da haka, tasirin ba a bayyane yake ba don kewayen mil 20. Hoto na 2 yana nuna sakamakon gwaji na kayan kewayawa guda biyu tare da rashin ƙarfi daban-daban, watau Rogers RO4350B™ daidaitaccen kayan kewayawa tare da babban roughness da Rogers RO4350B LoPro™ kayan kewayawa tare da ƙarancin ƙarancin ƙarfi.

Kamar yadda aka nuna a Hoto na 1 da Hoto na 2, mafi ƙarancin da’irar da’irar, mafi girma asarar shigar da kewaye. Wannan yana nufin cewa lokacin da ake ciyar da da’irar tare da wani adadin wutar lantarki na RF, mafi ƙarancin kewayawa zai haifar da ƙarin zafi. Lokacin da ake auna batun dumama da’ira, a gefe guda, da’ira mai sirara takan haifar da zafi fiye da da’ira mai kauri a manyan matakan wutar lantarki, amma a daya bangaren kuma, da’ira na iya samun ingantacciyar zazzafar zafi ta cikin ma’aunin zafi. Ci gaba da yanayin zafi kadan.

Domin warware matsalar dumama na kewaye, manufa bakin ciki da’ira ya kamata da wadannan halaye: low asarar factor na kewaye abu, m jan karfe bakin ciki surface, low εr da high thermal watsin. Idan aka kwatanta da kayan kewayawa na babban εr, mai sarrafa nisa na irin wannan impedance da aka samu a ƙarƙashin yanayin ƙananan εr na iya zama mafi girma, wanda ke da amfani don rage asarar mai gudanarwa na kewaye. Daga mahangar ɓarkewar zafi na kewaye, kodayake mafi yawan abubuwan da’ira na PCB masu ƙarfi suna da ƙarancin ƙarancin zafi dangane da masu gudanarwa, yanayin yanayin zafi na kayan kewayawa har yanzu yana da matukar mahimmanci.

Tattaunawa da yawa game da ma’aunin zafin jiki na abubuwan da’irar da’ira an yi bayani dalla-dalla a cikin labarin da suka gabata, kuma wannan labarin zai faɗi wasu sakamako da bayanai daga abubuwan da suka gabata. Misali, ma’auni mai zuwa da Hoto na 3 suna da taimako don fahimtar abubuwan da suka danganci aikin zafi na kayan da’ira na PCB. A cikin equation, k shine thermal conductivity (W/m/K), A shine yanki, TH shine zafin jiki na tushen zafi, TC shine yanayin sanyi, kuma L shine nisa tsakanin tushen zafi da tushen sanyi.