Nekuda kwehukuru hudiki uye saizi, hapana anenge aripo akadhindwa edunhu bhodhi zviyero zvemusika unopfekwa weIoT. Aya mazinga asati abuda, taifanira kuvimba neruzivo uye ruzivo rwekugadzira rwakadzidzwa mubhodhi-chikamu chekusimudzira uye kufunga nezve mashandisiro azvo kune akasiyana matambudziko ari kubuda. Pane nzvimbo nhatu dzinoda kutarisisa kwedu. Iwo ndeaya: redunhu bhodhi pamusoro zvinhu, RF/microwave dhizaini uye RF kutapurirana mitsetse.

PCB zvinhu

"PCB" kazhinji ine laminates, inogona kugadzirwa nefiber-reinforced epoxy (FR4), polyimide kana Rogers zvinhu kana zvimwewo laminate. Iyo inodzivirira zvinhu pakati pezvikamu zvakasiyana inonzi prepreg.

midziyo inopfeka inoda kuvimbika kwakanyanya, saka kana PCB vagadziri vakatarisana nesarudzo yekushandisa FR4 (iyo inodhura-inoshanda PCB kugadzira zvinhu) kana zvimwe zvemberi uye zvinodhura zvinhu, izvi zvinova dambudziko.

Kana zvinopfekwa zvePCB zvikumbiro zvinoda yakakwirira-kumhanya, yakakwirira-frequency zvinhu, FR4 inogona kunge isiri iyo yakanakisa sarudzo. Iyo dielectric constant (Dk) yeFR4 ndeye 4.5, iyo dielectric garage yeyakanyanya advanced Rogers 4003 series zvinhu ndeye 3.55, uye dielectric constant yehama dzakatevedzana Rogers 4350 ndeye 3.66.

"Dielectric constant yelaminate inoreva reshiyo yecapacitance kana simba pakati pemakondakita ari padyo nelaminate kune capacitance kana simba pakati pemakondukita maviri ari muvacuum. Pamafaro epamusoro, zviri nani kuve nekurasikirwa kudiki. Nokudaro, Roger 4350 ine dielectric constant ye3.66 inonyanya kukodzera kushandiswa kwepamusoro kwepamusoro pane FR4 ine dielectric constant ye4.5.

Mumamiriro ezvinhu akajairwa, nhamba yePCB layers yemidziyo inopfekeka inotangira pa4 kusvika pa8 layer. Nheyo yekugadzira dhizaini ndeyokuti kana iri 8-layer PCB, inofanira kukwanisa kupa zvakakwana pasi uye masimba emagetsi uye sandwich iyo wiring layer. Nenzira iyi, ripple mhedzisiro mucrosstalk inogona kuchengetwa kusvika padiki uye electromagnetic interference (EMI) inogona kudzikiswa zvakanyanya.

Muchikamu chebhodhi dhizaini yekugadzira dhizaini, hurongwa hwemagadzirirwo kazhinji hwekuisa yakakura pasi dhiza padhuze neiyo simba rekugovera layer. Izvi zvinogona kuumba yakaderera ripple maitiro, uye ruzha rwehurongwa hunogonawo kudzikiswa kusvika kunenge zero. Izvi zvakanyanya kukosha kune redhiyo frequency subsystem.

Kuenzaniswa neRogers zvinhu, FR4 ine yakakwira dissipation factor (Df), kunyanya pakakwirira frequency. Pakuita kwepamusoro FR4 laminates, kukosha kweDf kunosvika 0.002, iri kurongeka kwehukuru huri nani pane zvakajairika FR4. Nekudaro, Rogers 'stack ingori 0.001 kana zvishoma. Kana FR4 zvinhu zvichishandiswa kune yakakwira frequency application, pachave nemusiyano wakakura mukurasikirwa kwekuisa. Kurasikirwa kwekupinza kunotsanangurwa sekurasikirwa kwesimba kwechiratidzo kubva padanho A kusvika kunongedzo B paunenge uchishandisa FR4, Rogers kana zvimwe zvinhu.

kugadzira matambudziko

Inopfeka PCB inoda kuomesera impedance control. Ichi chinhu chakakosha pamidziyo inopfekwa. Impedance yekuenzanisa inogona kuburitsa yakachena chiratidzo kutapurirana. Pakutanga, iyo yakajairwa kushivirira kwechiratidzo chekutakura mitsetse yaive ± 10%. Ichi chiratidzo chiri pachena kuti hachina kunaka kune yanhasi yakakwirira-frequency uye yakakwirira-kumhanya maseketi. Chinodiwa parizvino ± 7%, uye mune dzimwe nguva kunyange ± 5% kana pasi. Iyi parameter uye zvimwe zvinosiyana zvinokanganisa zvakanyanya kugadzirwa kweaya anopfekeka maPCB ane kunyanya kuomesera impedance control, nekudaro kudzikisira huwandu hwemabhizinesi anogona kuvagadzira.

Iyo dielectric inogara kushivirira yelaminate yakagadzirwa neRogers UHF zvinhu zvinowanzo chengetwa pa ± 2%, uye zvimwe zvigadzirwa zvinogona kutosvika ± 1%. Kusiyana neizvi, iyo dielectric inogara kushivirira yeFR4 laminate yakakwira se10%. Naizvozvo, enzanisa Izvi zvinhu zviviri zvinogona kuwanikwa kuti Rogers 'kuisa kurasikirwa kwakanyanya kuderera. Kuenzaniswa neyechinyakare FR4 zvinhu, kurasikirwa kwekutapurirana uye kurasikirwa kwekuisa kweRogers stack kwakadzikira hafu.

Muzviitiko zvakawanda, mari ndiyo inonyanya kukosha. Nekudaro, Rogers inogona kupa yakaderera-kurasikirwa yakakwira-frequency laminate performance pane inogamuchirwa mutengo poindi. Zvekushandisa zvekutengesa, Rogers inogona kugadzirwa kuita hybrid PCB ine epoxy-based FR4, mamwe mataira ayo anoshandisa Rogers zvinhu, uye mamwe maseru anoshandisa FR4.

Pakusarudza Rogers stack, frequency ndiyo yekutanga kufunga. Kana iyo frequency ichipfuura 500MHz, PCB vagadziri vanowanzo sarudza Rogers zvinhu, kunyanya zveRF / microwave maseketi, nekuti zvinhu izvi zvinogona kupa mashandiro epamusoro kana zviteshi zvekumusoro zvichinyatsodzorwa ne impedance.

Kuenzaniswa neFR4 zvinhu, Rogers zvinhu zvinogona zvakare kupa yakaderera dielectric kurasikirwa, uye yayo dielectric kugara yakagadzikana mune yakakura frequency renji. Uye zvakare, Rogers zvinhu zvinogona kupa yakanakira yakaderera yekuisa kurasikirwa kuita kunodiwa nepamusoro frequency kushanda.

Iyo coefficient yekuwedzera kwemafuta (CTE) yeRogers 4000 akatevedzana zvinhu ane yakanakisa dimensional kugadzikana. Izvi zvinoreva kuti kana zvichienzaniswa neFR4, iyo PCB painotonhora, inopisa uye inopisa kwazvo kuyerera kwekutengesa kutenderera, iyo yekuwedzera yekupisa uye kudonhedza kwebhodhi redunhu inogona kuchengetedzwa padanho rakagadzikana pasi pepamusoro frequency uye yakakwirira tembiricha kutenderera.

Panyaya yekusanganiswa stacking, zviri nyore kushandisa zvakajairika kugadzira tekinoroji kusanganisa Rogers uye yakakwirira-inoshanda FR4 pamwe chete, saka zviri nyore kuwana yakakwirira yekugadzira goho. Iyo Rogers stack haidi yakakosha kuburikidza nekugadzirira maitiro.

Yakajairika FR4 haigone kuwana yakavimbika kuita kwemagetsi kuita, asi yakakwirira-inoshanda FR4 zvinhu zvine yakanaka kuvimbika hunhu, senge yakakwira Tg, ichiri yakaderera mutengo, uye inogona kushandiswa mumhando dzakasiyana dzekushandisa, kubva nyore dhizaini dhizaini kuenda kuComplex microwave application. .

RF/Microwave dhizaini kufunga

Inotakurika tekinoroji uye Bluetooth yakagadzira nzira yeRF/microwave application mumidziyo inopfekwa. Mazuva ano frequency range iri kuramba ichiwedzera simba. Makore mashoma apfuura, yakakwira frequency (VHF) yakatsanangurwa se2GHz ~ 3GHz. Asi ikozvino isu tinogona kuona Ultra-yakakwirira frequency (UHF) maapplication kubva ku10GHz kusvika 25GHz.

Naizvozvo, kune iyo inopfekwa PCB, chikamu cheRF chinoda kutariswa zvakanyanya kunyaya dzewaya, uye masaini anofanirwa kupatsanurwa zvakasiyana, uye zviteshi zvinoburitsa masaini akakwira-frequency anofanirwa kuchengetedzwa kure nepasi. Zvimwe zvinotariswa zvinosanganisira: kupa bypass sefa, yakakwana decoupling capacitors, grounding, uye kugadzira tambo yekutumira uye mutsara wekudzoka kuti uenzane.

Bypass sefa inogona kudzvanya ripple mhedzisiro yeruzha rwemukati uye crosstalk. Decoupling capacitors inoda kuiswa padyo nemapini emudziyo anotakura masaini emagetsi.

High-speed transmission tambo uye masignal circuits anoda pasi pekuisa pakati pesimba remagetsi masaini kutsvedzerera jitter inogadzirwa nemasaini eruzha. Pakumhanya kwechiratidzo chepamusoro, diki impedance mismatches inokonzeresa kutapurirana uye kugamuchirwa kwemasaini, zvichikonzera kukanganisa. Naizvozvo, kutarisisa kwakanyanya kunofanirwa kubhadharwa kune iyo impedance yekufananidza dambudziko rine chekuita neredhiyo frequency siginecha, nekuti redhiyo frequency siginecha ine kumhanya kwakanyanya uye kushivirira kwakakosha.

RF yekufambisa mitsara inoda inodzorwa impedance kuitira kufambisa masaini eRF kubva kune chaiyo IC substrate kuenda kuPCB. Aya mitsara yekutapurirana inogona kuitwa pane yekunze layer, yepamusoro layer, uye yepasi layer, kana inogona kugadzirwa pakati.

Nzira dzinoshandiswa panguva yePCB RF dhizaini dhizaini ndeye microstrip mutsara, inoyangarara mitsetse mutsara, coplanar waveguide kana pasi. Mutsara we microstrip unosanganisira kureba kwakatarwa kwesimbi kana mitsara uye ndege yose yepasi kana chikamu chepasi pasi zvakananga pasi payo. Iyo hunhu impedance mune yakajairika microstrip mutsara chimiro kubva ku50Ω kusvika 75Ω.

Inoyangarara stripline ndiyo imwe nzira yewaya uye kudzvinyirira ruzha. Mutsara uyu unoumbwa ne-fixed-width wiring pachikamu chemukati uye ndege huru yepasi kumusoro uye pasi pepakati conductor. Iyo ndege yepasi yakanyungudutswa pakati peiyo ndege yemagetsi, saka inogona kupa yakanyatso kudzika pasi. Iyi ndiyo nzira yakasarudzika yekupfekeka PCB RF chiratidzo wiring.

Coplanar waveguide inogona kupa kuzviparadzanisa nevamwe padhuze neRF wedunhu uye dunhu rinoda kufambiswa padyo. Iyi svikiro ine yepakati conductor uye ndege dzepasi kumativi ese kana pasi. Nzira yakanakisa yekufambisa masaisai eredhiyo ndeyekumisa mitsetse yemitsara kana coplanar waveguides. Idzi nzira mbiri dzinogona kupa kuzviparadzanisa pakati pechiratidzo uye RF traces.

Inokurudzirwa kushandisa iyo inonzi "kuburikidza nefenzi" pamativi ese eiyo coplanar waveguide. Iyi nzira inogona kupa mutsara wepasi vias pane imwe neimwe simbi pasi ndege yepakati kondakita. Mucherechedzo mukuru unomhanya nepakati une fenzi parutivi rumwe norumwe, nokudaro uchipa nzira yekudimbudzira yezvino kudzoka pasi pasi. Iyi nzira inogona kuderedza chiyero cheruzha chakabatana neakakwira ripple maitiro eiyo RF chiratidzo. Dielectric constant ye4.5 inoramba yakafanana neFR4 material ye prepreg, nepo dielectric constant ye prepreg-kubva microstrip, stripline or offset stripline-inenge 3.8 kusvika 3.9.

Mune mamwe maturusi anoshandisa pasi ndege, mapofu vias anogona kushandiswa kunatsiridza decoupling kuita simba capacitor uye kupa shunt nzira kubva mudziyo kusvika pasi. Iyo shunt nzira yekuenda pasi inogona kupfupisa kureba kweiyo via. Izvi zvinogona kuzadzisa zvinangwa zviviri: haungogadziri shunt kana pasi, asi zvakare kuderedza kureba kwekufambisa kwemidziyo ine nzvimbo diki, inova yakakosha RF dhizaini chinhu.