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 loss depends on many circuit parameters such as operating frequency, circuit substrate thickness, PCB dielectric constant (relative dielectric constant or εr) and design plan. As far as design schemes are concerned, radiation loss often stems from poor impedance transformation in the circuit or electromagnetic waves in the circuit. The difference in transmission. Circuit impedance transformation area usually includes signal feed-in area, step impedance point, stub and matching network. Reasonable circuit design can realize smooth impedance transformation, thereby reducing the radiation loss of the circuit. Of course, it should be realized that there is the possibility of impedance mismatch leading to radiation loss at any interface of the circuit. From the point of view of operating frequency, usually the higher the frequency, the greater the radiation loss of the circuit.

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.

Bayan yin watsi da asarar hasken da ke ƙasa da 20GHz, asarar shigar da layin watsa layin microstrip ya ƙunshi sassa biyu: asarar dielectric da asarar madugu. Matsakaicin su biyun ya dogara ne akan kauri na madauri. Don ƙananan sassa, asarar madugu shine babban sashi. Don dalilai da yawa, yana da wahala gabaɗaya a iya hasashen asarar madugu daidai. Alal misali, ƙaƙƙarfan saman madugu yana da babban tasiri akan halayen watsawa na igiyoyin lantarki. Ƙaƙƙarfan bangon jan ƙarfe ba kawai zai canza yaɗuwar igiyoyin lantarki ba na da’irar microstrip ba, har ma yana ƙara asarar madugu na kewaye. Saboda tasirin fata, tasirin tagulla mai kauri akan asarar madugu shima ya dogara da mitar. Hoto na 1 yana kwatanta asarar sakawa na 50 ohm microstrip layin watsa layin watsawa dangane da kaurin PCB daban-daban, waɗanda mils 6.6 da mil 10 ne, bi da bi.

The simulation results are obtained using Rogers Corporation’s MWI-2010 microwave impedance calculation software. The MWI-2010 software quotes the analytical equations in the classic papers in the field of microstrip line modeling. The test data in Figure 1 is obtained by the differential length measurement method of a vector network analyzer. It can be seen from Fig. 1 that the simulation results of the total loss curve are basically consistent with the measured results. It can be seen from the figure that the conductor loss of the thinner circuit (the curve on the left corresponds to a thickness of 6.6 mil) is the main component of the total insertion loss. As the circuit thickness increases (the thickness corresponding to the curve on the right is 10mil), the dielectric loss and the conductor loss tend to approach, and the two together constitute the total insertion loss.

The circuit material parameters used in the simulation model and the actual circuit are: dielectric constant 3.66, loss factor 0.0037, and copper conductor surface roughness 2.8 um RMS. When the surface roughness of the copper foil under the same circuit material is reduced, the conductor loss of the 6.6 mil and 10 mil circuits in Figure 1 will be significantly reduced; however, the effect is not obvious for the 20 mil circuit. Figure 2 shows the test results of two circuit materials with different roughness, namely Rogers RO4350B™ standard circuit material with high roughness and Rogers RO4350B LoPro™ circuit material with low roughness.

For thinner substrates, the use of smooth copper foil can significantly reduce the insertion loss. For the 6.6mil substrate, the insertion loss is reduced by 0.3 dB due to the use of smooth copper foil at 20GHz; the 10mil substrate is reduced by 0.22 dB at 20GHz; and the 20mil substrate, the insertion loss is only reduced by 0.11 dB.

This means that when the circuit is fed with a certain amount of RF microwave power, the thinner the circuit will generate more heat. When comprehensively weighing the issue of circuit heating, on the one hand, a thinner circuit generates more heat than a thick circuit at high power levels, but on the other hand, a thinner circuit can obtain more effective heat flow through the heat sink. Keep the temperature relatively low.

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.