Faʻafefea ona pulea PCB impedance?

Without impedance control, considerable signal reflection and distortion will be caused, resulting in design failure. Faʻailoga masani, e pei o le PCI pasi, PCI-E pasi, USB, Ethernet, DDR manatuaina, faʻailoga LVDS, ma isi mea uma, e manaʻomia le faʻatonutonuina o faʻafitauli. Impedance control ultimately needs to be realized through PCB design, which also puts forward higher requirements for PCB board technology. After communication with PCB factory and combined with the use of EDA software, the impedance of wiring is controlled according to the requirements of signal integrity.

Eseese metotia metotia mafai ona fuafuaina e maua ai le tutusa impedance aoga.

Microstrip lines

• E i ai le fasimea o uaea ma le eleele vaʻalele ma dielectric i le ogatotonu. Afai o le dielectric tumau, o le lautele o le laina, ma lona mamao mai le eleele vaʻalele e mafai ona faʻatonutonuina, ona lona uiga faʻafitauli e mafai ona faʻatonutonuina, ma o le saʻo o le a i totonu o le ± 5%.

What is impedance control how to perform impedance control on PCB

Laina tosi

O le lipine laina o se fasi ‘apamemea i le ogatotonu o le dielectric i le va o vaʻavaʻaia vaʻalele e lua. If the thickness and width of the line, the dielectric constant of the medium, and the distance between the ground planes of the two layers are controllable, the characteristic impedance of the line is controllable, and the accuracy is within 10%.

What is impedance control how to perform impedance control on PCB

The structure of multi-layer board:

Ina ia mafai ona faʻatonutonu PCB impedance lelei, e tatau ona malamalama i le faʻavae o PCB:

E masani lava o le mea matou te taʻua o le multilayer board e faia i luga o le ipu autu ma le semi-solidified sheet laminated faʻatasi ma le tasi. Koru laupapa o se faigata, faʻapitoa faʻapitoa mafiafia, lua areto ipu ‘apamemea, o le autu mea o le lolomi laupapa. And the semi-cured piece constitutes the so-called infiltration layer, plays the role of bonding the core plate, although there is a certain initial thickness, but in the process of pressing its thickness will occur some changes.

E masani lava o lapisi pito i fafo e lua o le multilayer o loʻo susu susu, ma e tuʻu eseʻesega apa apa apamemea o loʻo faʻaaogaina i fafo atu o nei vaega e lua e pei o le pito i fafo apamemea foil. O le uluaʻi mafiafia faʻamatalaga o fafo atu apamemea foil ma totonu apamemea foil e masani lava 0.5oz, 1OZ, 2OZ (1OZ e tusa ma le 35um poʻo le 1.4mil), ae a maeʻa se faʻasologa o luga togafitiga, o le mulimuli mafiafia o pito i fafo foil apamemea o le a faʻateleina faateleina e uiga i 1OZ O le pito i totonu apamemea foil o le apamemea ufiufi i itu uma o le autu ipu. O le mafiafia mulimuli e tau eseʻese mai le amataga mafiafia, ae e masani ona faʻaititia e le tele um ona o le faʻapipiʻi.

The outermost layer of the multilayer board is the welding resistance layer, which is what we often say “green oil”, of course, it can also be yellow or other colors. The thickness of the solder resistance layer is generally not easy to determine accurately. The area without copper foil on the surface is slightly thicker than the area with copper foil, but because of the lack of copper foil thickness, so the copper foil is still more prominent, when we touch the printed board surface with our fingers can feel.

Pe a faia se mafiafia faapitoa o le lolomi laupapa faia, i le tasi lima, talafeagai filifiliga o mea faʻatulagaina e manaʻomia, i le isi lima, o le mulimuli mafiafia o le semi-faʻamaloloina laupepa o le a laʻititi nai lo le amataga mafiafia. Lenei o le masani 6-vaega laminated fausaga:

What is impedance control how to perform impedance control on PCB

PCB parameters:

Different PCB plants have slight differences in PCB parameters. Through communication with circuit board plant technical support, we obtained some parameter data of the plant:

Luga pepa alumini kopa:

There are three thicknesses of copper foil that can be used: 12um, 18um and 35um. O le mafiafia mulimuli ina ua maeʻa e tusa o le 44um, 50um ma le 67um.

Ipu autu: S1141A, tulaga masani FR-4, lua areto ‘apamemea papatusi e masani ona faʻaaogaina. O filifiliga faʻapitoa e mafai ona fuafuaina e ala i le faʻafesoʻotaʻia o le kamupani gaosi.

Semi-cured tablet:

Specifications (original thickness) are 7628 (0.185mm), 2116 (0.105mm), 1080 (0.075mm), 3313 (0.095mm). The actual thickness after pressing is usually about 10-15um less than the original value. O le maualuga o le 3 semi-faʻamaloloina papa e mafai ona faʻaaogaina mo le tutusa infiltration vaega, ma le mafiafia o le 3 semi-faʻamaloloina papa e le mafai ona tutusa, a itiiti mai o le tasi afa faʻamaloloina papa e mafai ona faʻaaogaina, ae o ni gaosi tatau tatau ona faʻaaogaina le itiiti ifo i le lua . Afai o le mafiafia o le semi-faʻamalie fasi e le lava, o le apamemea pepa i luga o itu uma o le autu ipu mafai ona faʻailoaina ese, ma lea o le semi-faʻamaloloina fasi mafai ona fusia i itu uma e lua, ina ia mafai ai ona avea o se mafiafia sosolo infiltration ausia

Tetee maopoopo vaega:

O le mafiafia o le solder tetee vaega i luga o le apamemea pepa alumini o C2≈8-10um. O le mafiafia o le solder teteʻe vaega luga e aunoa ma apamemea foil o C1, lea e fesuisuiaʻi ma le mafiafia o apamemea luga. A o le mafiafia o le ‘apamemea luga o le pito i luga o le 45um, C1≈13-15um, ma pe a o le mafiafia o le’ apamemea i luga o le 70um, C1≈17-18um.

Vaega sopoia:

Matou te manatu o le kolosi vaega o le uaea o se tafatolu, ae o le mea moni o se trapezoid. Avea le TOP layer o se faʻataʻitaʻiga, pe a o le mafiafia o apamemea foil o 1OZ, o le pito i luga pito i lalo o trapezoid o 1MIL puʻupuʻu nai lo le pito i lalo lalo. Mo se faʻataʻitaʻiga, afai o le laina lautele o 5MIL, lona uiga o le pito i luga ma lalo itu e tusa ma le 4MIL ma le pito i lalo ma lalo itu e uiga i le 5MIL. O le eseesega i le va o pito i luga ma lalo e fesoʻotaʻi ma le mafiafia apamemea. O le siata o loʻo mulimuli mai e faʻaalia ai le sootaga i le va o le pito i luga ma le pito i lalo o le trapezoid i lalo o tuutuuga eseese.

What is impedance control how to perform impedance control on PCB

Permittivity: O le faʻatagaina o laupepa semi-faʻamaloloina e fesoʻotaʻi ma le mafiafia. O le siata o loʻo mulimuli mai o loʻo faʻaalia ai le mafiafia ma le faʻatagaina o tapulaʻa o ituaiga eseese o lauʻeseʻese faʻamalologa:

What is impedance control how to perform impedance control on PCB

O le dielectric tumau o le ipu e fesoʻotaʻi ma le resin mea na faʻaaogaina. O le dielectric tumau o le FR4 ipu o le 4.2 – 4.7, ma faʻaititia ma le faʻateleina o taimi.

Dielectric leiloa mea: dielectric mea i lalo o le gaioiga o fesuiaʻiga eletise fanua, ona o le vevela ma le malosi taumafaina ua taʻua o le dielectric leiloa, masani na faʻaalia e dielectric leiloa vaega Tan δ. O le tau masani mo S1141A o le 0.015.

Laʻititi laina lautele ma laina vavalalata ia mautinoa machining: 4mil / 4mil.

Impedance fuafuaina mea faigaluega faʻatomuaga:

A tatou malamalama i le faʻavae o le multilayer laupapa ma faʻataʻitaʻi ia manaʻomia tapulaʻa, e mafai ona tatou fuafuaina le impedance ala EDA polokalama. E mafai ona e faʻaaogaina Allegro e faia ai lenei mea, ae oute fautua ia Polar SI9000, ose mea faigaluega lelei lea mo le fuafuaina o faʻafitauli masani ma ua faʻaaogaina nei e le tele o fale gaosi PCB.

Pe a fuafuaina le faʻafitauli iloga o le faʻailo i totonu uma o le laina eseʻesega ma le tasi laina laina, o le a e mauaina na o sina laʻititi eseesega i le va o Polar SI9000 ma Allegro ona o ni auiliiliga, pei o le foliga o le koluse vaega o le uaea. Ae peitaʻi, afai o le a fuafua le faʻafitauli iloga o le Faʻailo luga, ou te fautua atu ia e filifilia le Coated faʻataʻitaʻi ae le o le laualuga faʻataʻitaʻiga, aua o ia ituaiga amanaia le i ai o solder tetee layer, o lea o le a sili atu ona saʻo iʻuga. Ole mea o loʻo sosoʻo mai o se vaega faʻamalamalamaina o le luga eseʻese laina laina faʻafuainumera fuafuaina ma Polar SI9000 iloiloina le solder tetee vaega:

What is impedance control how to perform impedance control on PCB

Talu ai o le mafiafia o le solder resist layer e le faigofie ona faʻatonutonuina, e mafai foi ona faʻaaogaina se auala latalata, e pei ona fautuaina e le kamupani gaosi oloa: toʻesea se faʻapitoa taua mai le Surface faʻataʻitaʻiga fuafuaina. E fautuaina o le eseʻesega impedance toʻesea 8 ohm ma le tasi-iʻuga impedance toʻesea 2 ohm.

Eseesega manaʻoga PCB mo uaea

(1) Fuafua le uila auala, tapulaʻa ma faʻafitauli fuafuaina. E i ai lua ituaiga o eseese auala mo laina laina: laina i fafo atu microstrip laina eseʻesega auala ma totonu laina fasi laina eseʻesega auala. Impedance mafai ona fuafuaina e fesoʻotaʻi impedance fuafua polokalama (pei o POLAR-SI9000) poʻo impedance fuafuaina metotia ala i le talafeagai parameter setiina.

(2) tutusa laina isometric. Fuafua le laina lautele ma le va, ma matua tausisi i le fuafuaina laina lautele ma le va pe a faʻasolosolo. O le vavalalata i le va o laina e lua e tatau ona tumau pea le suia, o lona uiga, ina ia tutusa. There are two ways of parallelism: one is that the two lines walk in the same side-by-side layer, and the other is that the two lines walk in the over-under layer. E masani ona taumafai e aloese mai le faʻaaogaina o le eseʻesega faʻailoilo i le va o faaputuga, mafua mai ona o le moni gaosiga o PCB i le gaioiga, ona o le cascading laminated faʻatulagaina saʻo sili atu maualalo nai lo saunia i le va o le tonu etching, ma i le faʻagasologa o laminated dielectric leiloa, le mafai faʻamautinoa laina laina vavalalata e tutusa ma le mafiafia o le interlayer dielectric, o le a mafua ai le eseʻesega i le va o vaega o le eseʻesega o faʻafitauli suia. E fautuaina e faʻaoga le eseʻesega i totonu ole laiga tutusa i le tele e mafai ai.