Pane nzira dzakawanda dzekugadzirisa matambudziko eEMI. Mazuvano EMI kudzvinyirira nzira dzinosanganisira: kushandisa EMI kudzvinyirira coatings, kusarudza akakodzera EMI kudzvinyirira zvikamu, uye EMI simulation dhizaini. Kutanga kubva kune yakanyanya kukosha PCB dhizaini, chinyorwa ichi chinokurukura nezve basa uye dhizaini matekiniki ePCB akaturikidzana akaturikidzana mukudzora EMI mwaranzi.

Kuisa zvine mutsindo macapacitor ehukuru hwakakodzera pedyo nemapini emagetsi eIC anogona kuita kuti IC inobuda magetsi isvetuke nekukurumidza. Zvisinei, dambudziko harigumiri pano. Nekuda kweiyo shoma frequency mhinduro ye capacitors, izvi zvinoita kuti ma capacitor atadze kuburitsa iyo harmonic simba rinodiwa kutyaira iyo IC inobuda zvakachena mu yakazara frequency bhendi. Uye zvakare, iyo yenguva pfupi voltage inoumbwa pamagetsi bhazi bar inoumba kudonha kwevoltage pamhiri peinductor yenzira yekubvisa. Aya mavheti enguva pfupi ndiwo akajairika maitiro EMI kupindira masosi. Tinofanira kugadzirisa sei matambudziko aya?

Nezve IC pabhodhi redu redunhu, iyo dhizaini yemagetsi yakatenderedza IC inogona kutariswa seyakanakisa high-frequency capacitor, inogona kuunganidza chikamu chesimba rakaburitswa ne discrete capacitor inopa yakakwirira-frequency simba rekuchenesa. output. Mukuwedzera, iyo inductance yesimba rakanaka remagetsi rinofanira kunge riri diki, saka chiratidzo chenguva pfupi chakagadzirwa neiyo inductance zvakare idiki, nekudaro ichidzikisa yakajairika mode EMI.

Zvechokwadi, kuwirirana pakati pesimba remagetsi uye IC simba pini kunofanira kuva pfupi sezvinobvira, nokuti iyo inokwira yedhijitari yedhijitari iri kukurumidza uye nekukurumidza, uye zviri nani kuibatanidza zvakananga kune padhi iyo IC simba. pin iripo. Izvi zvinoda kukurukurwa zvakasiyana.

Kuti udzore zvakajairika-modhi EMI, iyo ndege yemagetsi inofanirwa kubatsira kubvisa uye kuve neyakakwana yakaderera inductance. Iyi ndege yemagetsi inofanirwa kunge yakanyatsogadzirwa ndege dzemagetsi. Mumwe munhu angabvunza kuti, zvakanaka sei? Mhinduro kumubvunzo inoenderana nekuiswa kwesimba rekupa, zvinhu zviri pakati pematanho, uye frequency yekushanda (kureva, basa rekusimuka kweIC). Kazhinji, kupatsanurwa kwesimba remagetsi i6mil, uye iyo inopindirana ndeye FR4 zvinhu, yakaenzana capacitance yesimba regiyo pa sikweya inch inenge 75pF. Zviripachena, iyo diki diki kupatsanurwa, iyo yakakura capacitance.

Iko hakuna michina mizhinji ine nguva yekusimuka ye100 kusvika 300 ps, ​​asi zvinoenderana neikozvino IC budiriro yekumhanyisa, zvishandiso zvine nguva yekusimuka muchikamu che100 kusvika 300 ps zvichatora chikamu chepamusoro. Kumaseketi ane nguva yekusimuka ye100 kusvika 300ps, 3mil layer spacing haichakodzera kune akawanda maapplication. Panguva iyoyo, zvaive zvakafanira kushandisa tekinoroji yekuisa neraki spacing isingasviki 1 miriyoni, uye kutsiva FR4 dielectric zvinhu nemidziyo ine yakakwira dielectric constants. Ikozvino, ceramics nemapurasitiki e ceramic anogona kusangana nezvinodiwa zvekugadzira zve100 kusvika 300 ps kusimuka nguva maseketi.

Kunyangwe zvinhu zvitsva uye nzira itsva dzingashandiswa mune ramangwana, kune yanhasi yakajairika 1 kusvika 3ns kusimuka nguva maseketi, 3 kusvika 6mil layer spacing uye FR4 dielectric zvinhu, kazhinji inokwana kubata yakakwirira-yekupedzisira harmonic uye kuita kuti chiratidzo chenguva pfupi chidzike zvakakwana. , kureva kuti, Common mode EMI inogona kuderedzwa zvakanyanya. Iyo PCB yakaturikidzana yakaturikidzana dhizaini mienzaniso yakapihwa muchinyorwa chino ichatora yakaturikidzana nzvimbo ye3 kusvika 6 mils.

Electromagnetic shielding

Kubva pakuona kwechiratidzo chechiratidzo, nzira yakanaka yekuisa inofanira kunge iri yekuisa zviratidzo zvose zvechiratidzo pane imwe kana kupfuura, mitsara iyi iri padivi pesimba remagetsi kana pasi pasi. Nokuda kwekupa magetsi, nzira yakanaka yekuisa inofanira kunge iri iyo tambo yemagetsi iri pedyo nechepasi pasi, uye chinhambwe pakati pesimba remagetsi uye pasi pasi idiki sezvinobvira. Izvi ndizvo zvatinodaidza kuti “layer” zano.

PCB stacking

Ndeupi rudzi rwemaitiro ekurongedza anogona kubatsira kudzivirira uye kudzvanya EMI? Iyi inotevera layered stacking scheme inofunga kuti simba rekupa ikozvino rinoyerera pane imwechete layer, uye imwechete voltage kana akawanda voltages anogoverwa muzvikamu zvakasiyana zveiyo imwechete layer. Nyaya yemasimba akawanda emagetsi ichakurukurwa gare gare.

4-layer board

Kune akati wandei matambudziko anogona kuitika neiyo 4-layer board dhizaini. Chekutanga, iyo yechinyakare mana-layer board ine ukobvu hwe 62 mils, kunyangwe kana chiratidzo chechiratidzo chiri padenga rekunze, uye simba uye pasi pasi zviri mukati memukati, chinhambwe chiri pakati pesimba uye pasi pasi. ichiri yakakura.

Kana mari inodiwa iri yekutanga, unogona kufunga nzira mbiri dzinotevera kune yechinyakare 4-layer board. Mhinduro mbiri idzi dzinogona kuvandudza mashandiro eEMI kudzvanya, asi dzinongokodzera maapplication apo chikamu che density pabhodhi chakaderera zvakakwana uye pane nzvimbo yakakwana yakatenderedza zvikamu (isa inodiwa simba rendarira layer).

Sarudzo yekutanga ndiyo yekutanga sarudzo. Iwo ekunze akaturikidzana ePCB ese ari pasi pasi, uye maviri epakati akaturikidzana chiratidzo/simba matinji. Simba rekupa pane chiratidzo chechiratidzo chinofambiswa nemutsara wakafara, izvo zvinogona kuita kuti nzira yekudzivirira kwesimba rekupa ikozvino yadzike, uye iyo impedance yechiratidzo microstrip nzira zvakare yakaderera. Kubva pamaonero eEMI control, iyi ndiyo yakanakisa 4-layer PCB chimiro chiripo. Muchirongwa chechipiri, chikamu chekunze chinoshandisa simba uye pasi, uye maviri epakati anoshandisa zviratidzo. Kuenzaniswa neyechinyakare 4-layer board, iyo gadziriso idiki, uye iyo interlayer impedance haina kunaka seyakajairwa 4-layer board.

Kana iwe uchida kudzora trace impedance, iri pamusoro stacking chirongwa chinofanira kungwarira kwazvo kuronga maronda pasi pesimba uye pasi zvitsuwa zvemhangura. Mukuwedzera, zvitsuwa zvemhangura pamagetsi emagetsi kana pasi pasi zvinofanira kubatanidzwa zvakanyanya sezvinobvira kuitira kuti DC uye yakaderera-frequency yekubatanidza.

6-layer board

Kana iyo density yezvikamu pa4-layer board yakakura, 6-layer board ndiyo yakanaka. Nekudaro, mamwe marongero ezvirongwa mu6-layer board dhizaini haana kunaka zvakakwana kudzivirira iyo electromagnetic munda, uye ane zvishoma zvazvinoita pakudzikiswa kwechiratidzo chenguva pfupi chebhazi remagetsi. Mienzaniso miviri inokurukurwa pasi apa.

Muchiitiko chekutanga, magetsi uye pasi zvinoiswa pa 2nd uye 5th layers maererano. Nekuda kweiyo yakakwira impedance yemhangura yekuputira magetsi, hazvina kunaka kudzora yakajairika modhi EMI radiation. Zvisinei, kubva pakuona kwechiratidzo che impedance control, iyi nzira yakarurama kwazvo.