Nigbati ifihan agbara igbohunsafẹfẹ giga/Makirowefu ti wa ni ifunni sinu PCB Circuit, isonu ti o ṣẹlẹ nipasẹ Circuit funrararẹ ati ohun elo Circuit yoo ṣe ina kan iye ooru kan. Ti o pọju pipadanu naa, agbara ti o ga julọ ti o kọja nipasẹ awọn ohun elo PCB, ati pe ooru ti o pọ sii. Nigbati iwọn otutu iṣiṣẹ ti Circuit ba kọja iye ti a ṣe, Circuit le fa awọn iṣoro diẹ. Fun apẹẹrẹ, paramita iṣẹ aṣoju MOT, eyiti a mọ daradara ni awọn PCBs, jẹ iwọn otutu ti o pọ julọ. Nigbati iwọn otutu iṣiṣẹ ba kọja MOT, iṣẹ ati igbẹkẹle ti Circuit PCB yoo ni ewu. Nipasẹ apapọ awoṣe itanna eletiriki ati awọn wiwọn idanwo, agbọye awọn abuda igbona ti awọn PCB makirowefu RF le ṣe iranlọwọ yago fun ibajẹ iṣẹ ṣiṣe Circuit ati ibajẹ igbẹkẹle ti o fa nipasẹ awọn iwọn otutu giga.

Imọye bi pipadanu ifibọ ṣe waye ninu awọn ohun elo iyika ṣe iranlọwọ lati ṣe apejuwe dara julọ awọn ifosiwewe pataki ti o ni ibatan si iṣẹ igbona ti awọn iyika PCB igbohunsafẹfẹ-giga. Nkan yii yoo gba Circuit laini gbigbe microstrip bi apẹẹrẹ lati jiroro lori awọn pipaṣẹ iṣowo ti o ni ibatan si iṣẹ igbona ti Circuit naa. Ninu iyika microstrip kan pẹlu eto PCB-apa meji, awọn adanu pẹlu pipadanu dielectric, adanu adaorin, ipadanu itankalẹ, ati pipadanu jijo. Awọn iyato laarin awọn ti o yatọ ipadanu irinše ni o tobi. Pẹlu awọn imukuro diẹ, pipadanu jijo ti awọn iyika PCB igbohunsafẹfẹ giga jẹ kekere pupọ. Ninu nkan yii, niwọn igba ti iye isonu jijo ti lọ silẹ pupọ, yoo ṣe akiyesi rẹ fun akoko naa.

Pipadanu Ìtọjú

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.

Awọn paramita ti awọn ohun elo iyika ti o ni ibatan si pipadanu itankalẹ jẹ igbagbogbo dielectric ati sisanra ohun elo PCB. Awọn nipon awọn Circuit sobusitireti, ti o tobi awọn seese ti nfa Ìtọjú pipadanu; isalẹ awọn εr ti awọn PCB awọn ohun elo ti, ti o tobi ni Ìtọjú isonu ti awọn Circuit. Ṣe iwọn awọn abuda ohun elo ni kikun, lilo awọn sobusitireti iyika tinrin le ṣee lo bi ọna lati ṣe aiṣedeede ipadanu isonu ti o ṣẹlẹ nipasẹ awọn ohun elo Circuit kekere. Ipa ti sisanra sobusitireti iyika ati εr lori ipadanu itankalẹ Circuit jẹ nitori pe o jẹ iṣẹ ti o gbẹkẹle igbohunsafẹfẹ. Nigbati sisanra ti sobusitireti iyika ko kọja 20mil ati igbohunsafẹfẹ iṣẹ jẹ kekere ju 20GHz, isonu isonu ti Circuit naa kere pupọ. Niwọn igba ti pupọ julọ awoṣe iyika ati awọn iwọn wiwọn ninu nkan yii kere ju 20GHz, ijiroro ninu nkan yii yoo foju ipa ti ipadanu itankalẹ lori alapapo Circuit.

Lẹhin aibikita ipadanu itankalẹ ni isalẹ 20GHz, pipadanu ifibọ ti Circuit laini gbigbe microstrip ni akọkọ pẹlu awọn ẹya meji: pipadanu dielectric ati adanu adaorin. Awọn ipin ti awọn meji o kun da lori awọn sisanra ti awọn Circuit sobusitireti. Fun awọn sobusitireti tinrin, ipadanu adaorin jẹ paati akọkọ. Fun ọpọlọpọ awọn idi, o ṣoro ni gbogbogbo lati sọ asọtẹlẹ pipadanu adaorin ni deede. Fun apẹẹrẹ, aibikita dada ti adaorin kan ni ipa nla lori awọn abuda gbigbe ti awọn igbi itanna eletiriki. Awọn dada roughness ti Ejò bankanje yoo ko nikan yi awọn itanna igbi soju ibakan ti awọn microstrip Circuit, sugbon tun mu awọn adaorin isonu ti awọn Circuit. Nitori ipa awọ-ara, ipa ti aibikita bankanje bàbà lori pipadanu adaorin tun jẹ igbẹkẹle-igbohunsafẹfẹ. Nọmba 1 ṣe afiwe pipadanu ifibọ ti awọn iyika laini gbigbe microstrip 50 ohm ti o da lori awọn sisanra PCB oriṣiriṣi, eyiti o jẹ 6.6 mils ati 10 mils, lẹsẹsẹ.

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.

Ni ibere lati yanju awọn alapapo isoro ti awọn Circuit, awọn bojumu tinrin Circuit yẹ ki o ni awọn wọnyi abuda: kekere isonu ifosiwewe ti awọn Circuit ohun elo, dan Ejò tinrin dada, kekere εr ati ki o ga gbona iba ina elekitiriki. Ti a bawe pẹlu ohun elo Circuit ti εr giga, iwọn adaorin ti impedance kanna ti a gba labẹ ipo kekere εr le jẹ tobi, eyiti o jẹ anfani lati dinku isonu adaorin ti Circuit naa. Lati iwoye ti itusilẹ ooru Circuit, botilẹjẹpe awọn sobusitireti iyika PCB igbohunsafẹfẹ giga-giga julọ ni ibaamu igbona igbona ti ko dara pupọ si awọn olutọpa, imudara igbona ti awọn ohun elo iyika tun jẹ paramita pataki pupọ.

Pupọ ti awọn ijiroro nipa iṣesi igbona ti awọn sobusitireti iyika ni a ti ṣe alaye ni awọn nkan iṣaaju, ati pe nkan yii yoo sọ diẹ ninu awọn abajade ati alaye lati awọn nkan iṣaaju. Fun apẹẹrẹ, idogba atẹle ati Nọmba 3 ṣe iranlọwọ lati ni oye awọn nkan ti o nii ṣe pẹlu iṣẹ igbona ti awọn ohun elo Circuit PCB. Ni idogba, k jẹ ifarapa igbona (W/m/K), A ni agbegbe, TH ni iwọn otutu ti orisun ooru, TC jẹ iwọn otutu ti orisun tutu, ati L jẹ aaye laarin orisun ooru ati orisun tutu.