PCB cov ntaub ntawv kev lag luam tau siv sijhawm ntau los tsim cov ntaub ntawv uas muab cov teeb liab poob qis tshaj plaws. Rau kev kub ceev thiab kev tsim ntau zaus, kev poob yuav txwv tsis pub tshaj tawm qhov deb thiab cuam tshuam cov teeb liab, thiab nws yuav tsim ib qho impedance sib txawv uas tuaj yeem pom hauv TDR ntsuas. Raws li peb tsim cov ntawv luam tawm Circuit Board thiab tsim cov circuits uas ua haujlwm ntawm cov zaus ntau dua, nws yuav yog qhov txaus siab rau xaiv qhov zoo tshaj plaws tooj liab hauv txhua qhov tsim koj tsim.

Thaum nws muaj tseeb tias tooj liab roughness tsim ntxiv impedance sib txawv thiab kev poob, koj cov ntawv ci tooj liab yuav tsum zoo li cas? Puas muaj qee txoj hauv kev yooj yim uas koj tuaj yeem siv los kov yeej kev poob yam tsis tau xaiv cov tooj liab ultra-nplua rau txhua tus qauv? Peb mam li saib cov ntsiab lus hauv tsab xov xwm no, nrog rau qhov koj tuaj yeem nrhiav yog tias koj pib yuav khoom rau PCB stackup cov ntaub ntawv.

Hom ntawmPCB Copper Ntawv Nyiaj

Nquag thaum peb tham txog tooj liab ntawm PCB cov ntaub ntawv, peb tsis tham txog yam tshwj xeeb ntawm tooj liab, peb tsuas yog tham txog nws qhov roughness. Cov txheej txheem tooj liab sib txawv tsim cov yeeb yaj kiab uas muaj qhov sib txawv ntawm qhov sib txawv, uas tuaj yeem ua kom pom tseeb hauv daim duab scanning electron microscope (SEM). Yog hais tias koj yuav ua hauj lwm ntawm high zaus (feem ntau 5 GHz WiFi los yog saum toj no) los yog nyob rau hauv high speeds, ces xyuam xim rau cov tooj liab hom teev nyob rau hauv koj cov ntaub ntawv cov ntaub ntawv.

Tsis tas li, nco ntsoov nkag siab lub ntsiab lus ntawm Dk qhov tseem ceeb hauv daim ntawv teev cov ntaub ntawv. Saib qhov kev sib tham podcast no nrog John Coonrod los ntawm Rogers kom paub ntau ntxiv txog Dk specifications. Nrog rau qhov ntawd hauv siab, cia peb saib qee qhov sib txawv ntawm PCB tooj liab ntawv ci.

Electrodeposited

Hauv cov txheej txheem no, lub nruas yog spun los ntawm cov tshuaj electrolytic, thiab cov tshuaj tiv thaiv electrodeposition yog siv los "loj" cov ntawv ci tooj liab mus rau lub nruas. Raws li lub nruas rotates, qhov tshwm sim tooj liab zaj duab xis yog maj mam qhwv mus rau ib tug menyuam, muab ib daim ntawv txuas ntxiv ntawm tooj liab uas tuaj yeem tom qab dov mus rau lub laminate. Lub nruas sab ntawm lub tooj liab yuav tseem ceeb phim qhov roughness ntawm lub nruas, thaum lub sab sab yuav yog ntau rougher.

Electrodeposited PCB tooj liab ntawv ci

Electrodeposited tooj liab ntau lawm.
Txhawm rau siv rau hauv cov txheej txheem PCB txheej txheem, qhov ntxhib ntawm cov tooj liab yuav ua ntej raug khi rau iav-resin dielectric. Cov tooj liab uas tseem tshuav (nruas sab) yuav tsum tau txhob txwm roughened tshuaj (xws li, nrog ntshav etching) ua ntej nws yuav siv tau nyob rau hauv tus txheej txheem tooj liab clad lamination txheej txheem. Qhov no yuav xyuas kom meej tias nws tuaj yeem txuas mus rau txheej tom ntej hauv PCB stackup.

Deg-Thiab Electrodeposited Copper

Kuv tsis paub lub ntsiab lus zoo tshaj plaws uas suav nrog txhua yam sib txawv ntawm qhov chaw khotooj liab foils, yog li cov lus saum toj no. Cov ntaub ntawv tooj liab no zoo tshaj plaws hu ua cov ntawv kho rov qab, txawm tias muaj ob qho kev hloov pauv muaj nyob (saib hauv qab).

Rov qab kho foils siv cov kev kho deg uas siv rau sab du (nruas sab) ntawm daim ntawv electrodeposited tooj liab. Ib txheej kev kho mob tsuas yog txheej nyias nyias uas txhob txwm roughens cov tooj liab, yog li nws yuav muaj adhesion ntau dua rau cov khoom siv dielectric. Cov kev kho mob no kuj ua raws li oxidation barrier uas tiv thaiv corrosion. Thaum cov tooj liab no siv los tsim cov laminate panels, sab kho tau raug khi rau dielectric, thiab sab laug ntawm qhov ntxhib tseem raug. Sab sab yuav tsis xav tau ntxiv roughening ua ntej etching; nws yuav twb muaj zog txaus los khi rau txheej tom ntej hauv PCB stackup.

Peb qhov kev hloov pauv ntawm cov ntawv nyiaj rov qab kho tooj liab suav nrog:

High temperature elongation (HTE) copper foil: Qhov no yog ib qho electrodeposited tooj liab ntawv ci uas ua raws li IPC-4562 Qib 3 specifications. Lub ntsej muag raug kuj raug kho nrog oxidation barrier los tiv thaiv corrosion thaum lub sij hawm cia.
Muab ob npaug rau cov ntawv ci: Hauv daim ntawv tooj liab no, kev kho mob yog siv rau ob sab ntawm zaj duab xis. Cov khoom no qee zaum hu ua nruas-sab kho cov ntawv ci.
Resistive tooj liab: Qhov no tsis yog ib txwm cais raws li cov tooj liab kho saum npoo. Cov ntawv ci tooj liab no siv cov xim hlau txheej dhau ntawm matte sab ntawm tooj liab, uas yog tom qab ntawd roughened mus rau qib xav tau.
Daim ntawv thov kev kho deg nyob rau hauv cov ntaub ntawv tooj liab no yog ncaj nraim: cov ntawv ci yog dov los ntawm cov khoom siv electrolyte ntxiv uas siv cov tooj liab plating, ua raws li cov txheej txheem txheej txheej, thiab thaum kawg txheej txheej zaj duab xis los tiv thaiv tarnish.

PCB tooj liab ntawv ci

Kev kho deg txheej txheem rau tooj liab foils. [Source: Pytel, Steven G., et al. "Kev tshuaj xyuas ntawm kev kho tooj liab thiab qhov cuam tshuam ntawm cov teeb liab propagation." Nyob rau hauv 2008 58th Electronic Cheebtsam thiab Technology Conference, pp. 1144-1149. IB, 2008.]
Nrog rau cov txheej txheem no, koj muaj cov khoom siv uas tuaj yeem siv tau yooj yim hauv cov txheej txheem txheej txheem txheej txheem txheej txheem nrog kev ua haujlwm tsawg kawg nkaus.

Rolled-Annealed tooj liab

Rolled-annealed tooj liab foils yuav dhau ib yob ntawm tooj liab ntawv nyiaj los ntawm ib tug khub ntawm rollers, uas yuav txias-yob daim ntawv tooj liab mus rau qhov xav tau tuab. Qhov roughness ntawm cov ntawv ci uas tau tshwm sim yuav txawv nyob ntawm qhov tsis sib xws (ceev, siab, thiab lwm yam).

Cov ntawv ua tau tuaj yeem ua tau zoo heev, thiab cov striations pom nyob rau saum npoo ntawm daim ntawv dov-annealed tooj liab. Cov duab hauv qab no qhia txog kev sib piv ntawm cov ntawv ci electrodeposited tooj liab thiab cov ntawv ci dov-annealed.

PCB tooj liab ntawv sib piv

Kev sib piv ntawm electrodeposited vs. dov-annealed foils.
Low-Profile tooj liab
Qhov no tsis tas yuav yog hom ntawv tooj liab uas koj yuav fabricate nrog rau lwm txoj kev. Low-profile tooj liab yog electrodeposited tooj liab uas kho thiab hloov kho nrog cov txheej txheem micro-roughening los muab qhov nruab nrab roughness tsawg heev nrog txaus roughening rau adhesion rau lub substrate. Cov txheej txheem rau kev tsim cov ntawv ci tooj liab no feem ntau yog tus tswv. Cov foils no feem ntau categorized li ultra-low profile (ULP), tsawg profile (VLP), thiab yooj yim-profile (LP, kwv yees li 1 micron nruab nrab roughness).

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