A gaskiya ma, tsarin kula da impedance shine 10% sabawa. Dan kadan mai tsauri wanda zai iya cimma 8%. Akwai dalilai da yawa:

1. Da karkatar da takardar kayan kanta

2. Etching karkacewa a ciki PCB aiki

3. Maɓallai kamar ƙimar kwararar lalacewa ta hanyar lamination yayin sarrafa PCB

4. A babban gudun, rashin ƙarfi na farfajiyar murfin jan karfe, tasirin gilashin fiber na PP, tasirin canjin mitar DF ​​na matsakaici, da dai sauransu.

Don fahimtar impedance, dole ne ku fahimci sarrafawa. A cikin ƴan kasidu masu zuwa, bari mu dubi wasu ilimin sarrafa abubuwa. Na farko zai dubi lamination:

1. Ka’idar PCB dannawa

Babban manufar lamination shi ne hada PP tare da daban-daban core alluna da kuma m tagulla foils ta “zafi da matsa lamba”, da kuma amfani da waje tagulla foil a matsayin tushe na waje kewaye. Kuma daban-daban PP abun da ke ciki tare da daban-daban ciki farantin da surface jan karfe za a iya sanye take da daban-daban bayani dalla-dalla da kauri na kewaye allon. Tsarin latsawa shine mafi mahimmancin tsari a cikin kera allunan PCB multilayer, kuma dole ne ya dace da ainihin ingancin alamun PCB bayan dannawa.

1. Kauri: Yana ba da haɗin wutar lantarki mai alaƙa, kulawar impedance, da cika manne tsakanin yadudduka na ciki.

2. Haɗuwa: Samar da haɗin gwiwa tare da baƙar fata na ciki (launin ruwan kasa) da tagulla na waje.

3. girma kwanciyar hankali: The girma canji na kowane ciki Layer ne m don tabbatar da jeri daga cikin ramukan da zobba na kowane Layer.

4. Yakin allo: Kula da shimfidar allo.

2. PCB latsa tsari

Sharuɗɗan da dole ne a cika don aikin latsawa

A. Sharuɗɗan kayan aiki:

An yi katako mai mahimmanci na ciki na ƙirar jagora

Farin tagulla

Prepreg

B. Sharuɗɗan tsari:

high zafin jiki

high matsa lamba

3. Gabatarwa zuwa PP na kayan laminated

halayyar:

Properties na prepreg

A. RC% (abun ciki na Resin): yana nufin adadin nauyin nauyin resin a cikin fim sai dai gilashin gilashi. Adadin RC% kai tsaye yana rinjayar ikon resin don cika gibba tsakanin wayoyi, kuma a lokaci guda yana ƙayyade kauri na dielectric Layer bayan danna allon.

B. RF% (Resin flow): yana nufin adadin resin da ke gudana daga cikin allo zuwa jimlar nauyin prepreg na asali bayan danna allon. RF% ma’auni ne da ke nuna ruwa na guduro, kuma yana ƙayyade kauri daga cikin dielectric Layer bayan danna farantin.

C. VC% (abun ciki mai canzawa): yana nufin adadin ainihin nauyin abubuwan da ba a iya gani ba da aka rasa bayan an bushe prepreg. Adadin VC% kai tsaye yana rinjayar ingancin bayan latsawa.

aiki:

1. A matsayin haɗin haɗin gwiwa na ciki da na waje.

2. Samar da kauri mai insulating mai dacewa. Fim ɗin ya ƙunshi gilashin fiber zane da guduro. Bambance-bambancen kauri na fim ɗin gilashin fiber guda ɗaya bayan dannawa an daidaita shi ta hanyar abun ciki daban-daban na guduro maimakon yanayin latsawa.

3. Sarrafa impedance. Daga cikin manyan abubuwan da ke da tasiri guda hudu, ƙimar Dk da kauri na dielectric Layer an ƙaddara su ta hanyar halayen fim. Ana iya ƙididdige ƙimar Dk na fim ɗin da aka kafa ta hanyar dabara mai zuwa.

Dk=6.01-3.34RR: Gudun abun ciki%

Don haka, ana iya ƙididdige ƙimar Dk da aka yi amfani da ita lokacin da ake ƙididdige ƙaƙƙarfan ƙididdigewa bisa ƙimar gilashin fiber gilashi da resin a cikin haɗin fim ɗin laminated.

Ana ƙididdige ainihin kauri na PP bayan cikawa kamar haka:

Kauri bayan danna PP

1. Kauri = kauri mai kauri na asarar cikar PP guda ɗaya

2. Cike hasara = (1-A saman ciki Layer tagulla foil ragowar jan karfe) x Layer na ciki Layer tagulla kauri + (1-B surface na ciki Layer jan karfe foil ragowar jan karfe) x na ciki Layer tagulla kauri / 3, ciki Layer Residual kudin jan karfe = yankin wayoyi na ciki / duk yankin allo

Ragowar ƙimar tagulla na yadudduka biyu na ciki a cikin wannan adadi na sama sune kamar haka:

Da fatan za a kula da dabarar da ke sama. Idan muna ƙididdige asarar ciko na babban Layer na biyu, muna buƙatar ƙididdige gefe ɗaya kawai, ba ragowar adadin jan ƙarfe na Layer na waje ba. mai bi:

Cike hasara = (1-na ciki ragowar foil jan karfe) x kauri na tagulla na ciki

Tsarin tsarin matsawa

(1) Bakin ciki mai kauri mafi girma an fi son (mafi kyawun kwanciyar hankali)

(2) An fi son PP mai ƙarancin farashi (don nau’in zanen gilashi iri ɗaya PP, abun ciki na guduro da gaske baya shafar farashin)

(3) An fi son tsarin simmetric don guje wa PCB warpage bayan gama samfurin. Adadin da ke biyowa tsarin da ba shi da ma’auni ne kuma ba a ba da shawarar ba.

(4) Kauri daga cikin dielectric Layer》 kauri na ciki tagulla tsare ×2

(5) An haramta amfani da PP tare da ƙananan abun ciki na resin a cikin takarda ɗaya tsakanin 1-2 yadudduka da n-1/n, kamar 7628 × 1 (n shine adadin yadudduka)

(6) Don 3 ko fiye da prepregs da aka shirya tare ko kauri na dielectric Layer ya fi 25 mils, sai dai na waje da na ciki na PP, tsakiyar PP an maye gurbinsu da allon haske.

(7) Lokacin da Layer na biyu da n-1 sune 2oz na kasa jan karfe kuma kauri na 1-2 da n-1 / n Layer na insulating Layer bai wuce 14mil ba, an haramta amfani da PP guda ɗaya, kuma mafi girma. Layer yana buƙatar amfani da babban abun ciki na guduro PP. Kamar su 2116, 1080; idan ragowar jan karfe bai wuce 80% ba, gwada ƙoƙarin guje wa amfani da 1080PP guda ɗaya

(8) Na ciki Layer na jan karfe 1oz board, lokacin da 1-2 Layer da n-1 / n Layer amfani 1 PP, da PP bukatar yin amfani da babban guduro abun ciki, sai dai 7628×1

(9) An haramta amfani da PP guda ɗaya don allunan da ke da jan ƙarfe na ciki ≥ 3oz. Gabaɗaya, 7628 ba a amfani da shi. Dole ne a yi amfani da PP da yawa tare da babban abun ciki na guduro, kamar 106, 1080, 2116…

(10) Don allunan multilayer tare da wuraren da ba su da tagulla fiye da 3 ″ × 3″ ko 1″ × 5″, PP gabaɗaya ba a amfani da ita azaman takarda ɗaya tsakanin allunan ainihin.