A cikin tsarin ƙirar PCB, wasu injiniyoyi ba sa so su shimfiɗa tagulla a kan gabaɗayan saman Layer na ƙasa don adana lokaci. Shin wannan daidai ne? Shin dole ne PCB ya zama farantin tagulla?

Da farko, muna bukatar mu bayyana: kasa plating jan karfe yana da amfani kuma wajibi ne ga PCB, amma tagulla plating a kan dukan jirgin dole ne hadu da wasu sharudda.

Amfanin kasan tagulla plating
1. Daga ra'ayi na EMC, dukan saman Layer na ƙasa an rufe shi da tagulla, wanda ke ba da ƙarin kariya ta kariya da sautin murya don siginar ciki da siginar ciki. A lokaci guda kuma, tana da ƙayyadaddun kariyar kariya don kayan aiki da sigina na ƙasa.

2. Daga ra'ayi na zafi dissipation, saboda halin yanzu karuwa a PCB hukumar yawa, da BGA babban guntu kuma bukatar la'akari zafi dissipation al'amurran da suka shafi fiye da. Dukkanin allon da'ira an kafa shi da tagulla don inganta ƙarfin watsar da zafi na PCB.

3. Daga ra'ayi na tsari, dukkanin allon an kafa shi da tagulla don sanya allon PCB daidai da rarraba. PCB lankwasawa da warping ya kamata a kauce masa yayin sarrafa PCB da latsawa. A lokaci guda, damuwa da PCB reflow soldering ba zai haifar da rashin daidaituwar tagulla ba. PCB yaki.

Tunatarwa: Don allunan Layer biyu, ana buƙatar murfin jan karfe

A gefe guda, saboda allon mai layi biyu ba shi da cikakken jirgin sama, shimfidar ƙasa na iya samar da hanyar dawowa, kuma ana iya amfani da shi azaman ma'anar coplanar don cimma manufar sarrafa impedance. Yawancin lokaci za mu iya sanya jirgin kasa a kan Layer na kasa, sannan mu sanya manyan abubuwan da aka gyara da layin wutar lantarki da layin sigina a saman Layer. Don manyan da'irori na impedance, da'irori na analog (analog-zuwa-dijital juyawa da'irori, yanayin jujjuya wutar lantarki), platin jan karfe abu ne mai kyau.

Sharuɗɗa don platin jan karfe a ƙasa
Ko da yake ƙasan Layer na jan karfe ya dace da PCB, har yanzu yana buƙatar saduwa da wasu yanayi:

1. Kwanta kamar yadda zai yiwu a lokaci guda, kada ku rufe gaba daya, kauce wa fata na jan karfe daga tsagewa, da kuma ƙara ta cikin ramuka a kan layin ƙasa na yankin jan karfe.

Dalili: Dole ne a karye Layer Layer na jan karfe a saman saman da kuma lalata shi ta hanyar abubuwan da aka gyara da layukan sigina akan saman saman. Idan foil ɗin tagulla ba shi da kyau (musamman ma sirara da dogon foil ɗin tagulla ya karye), zai zama eriya kuma ya haifar da matsalolin EMI.

2. Yi la'akari da ma'auni na thermal na ƙananan fakiti, musamman ƙananan fakiti, kamar 0402 0603, don kauce wa tasiri mai mahimmanci.

Dalili: Idan dukkan allon da'ira ta kasance da tagulla, to za a haɗa tagulla na abubuwan fil ɗin gaba ɗaya da tagulla, wanda zai sa zafi ya ɓace da sauri, wanda zai haifar da matsala wajen rushewa da sake yin aiki.

3. The grounding na dukan PCB kewaye hukumar zai fi dacewa ci gaba da grounding. Ana buƙatar sarrafa nisa daga ƙasa zuwa sigina don guje wa tashewar layin watsawa.

Dalili: Tagulla takardar yana kusa da ƙasa zai canza impedance na microstrip watsa layin, da kuma katsewar tagulla takardar kuma zai yi wani mummunan tasiri a kan impedance katsewa na watsa line.

4. Wasu lokuta na musamman sun dogara da yanayin aikace-aikacen. Tsarin PCB bai kamata ya zama cikakkiyar ƙira ba, amma yakamata a auna shi kuma a haɗa shi da dabaru daban-daban.

Dalili: Bugu da ƙari ga sigina masu mahimmanci waɗanda ke buƙatar ƙasa, idan akwai layukan sigina masu sauri da yawa da kuma abubuwan haɗin gwiwa, za a samar da adadi mai yawa na ƙanana da dogayen tagulla, kuma tashoshi na waya suna da ƙarfi. Wajibi ne don kauce wa yawancin ramukan tagulla a kan farfajiya kamar yadda zai yiwu don haɗawa da ƙasa Layer. Layer na saman na iya zama tilas banda jan karfe.