Ukuxaka okwandayo kwe- PCB design considerations, such as clock, cross talk, impedance, detection, and manufacturing processes, often forces designers to repeat a lot of layout, verification, and maintenance work. Isihleli sokukhawulelwa kwepharamitha sihlanganisa lezi zinhlaka zibe amafomula ukusiza abaklami ukubhekana kangcono nale mingcele ephikisanayo kwesinye isikhathi ngesikhathi sokuklama nokukhiqiza.

Eminyakeni yamuva, ukuhlelwa kwe-PCB nezidingo zomzila seziyinkimbinkimbi, futhi inani lama-transistors kumasekhethi ahlanganisiwe lenyukile njengoba kwabikezelwa nguMthetho kaMorey, okwenza amadivayisi asheshe futhi ushayela ngamunye ube mfushane ngesikhathi sokuvuka, kanye nokwandisa inani lamaphini – imvamisa kungama-500 kuya ku-2,000 XNUMX. Konke lokhu kudala izinkinga zobuningi, iwashi, ne-crosstalk lapho kwaklanywa i-PCB.

Eminyakeni embalwa eyedlule, ama-PCBS amaningi ayenamadlanzana nje “abucayi” (Amanethi), ngokuvamile achazwa njengezithiyo ekubambeni impedance, ubude nasekuvunyweni. Abaklami be-PCB babezihambisa ngesandla le mizila bese besebenzisa isoftware ukwenza umzila omkhulu wesekethe yonke. Ama-PCBS anamuhla avame ukuba nezindawo ezingama-5,000 noma ngaphezulu, ngaphezulu kwe-50% yazo ezibucayi. Due to the time to market pressure, manual wiring is not possible at this point. Moreover, not only has the number of critical nodes increased, but the constraints on each node have also increased.

These constraints are mainly due to the correlation parameters and design requirements of more and more complex, for example, the two linear interval may depend on an and node voltage and circuit board materials are related functions, digital IC rise time decreases of high speed and low clock speed can influence the design, due to pulse faster and to establish and maintain a shorter time, In addition, as an important part of the total delay of high-speed circuit design, interconnect delay is also very important for low-speed design.

Ezinye zalezi zinkinga bekungaba lula ukuzixazulula uma amabhodi ebemakhulu, kepha ukuthambekela kukuphambene. Ngenxa yezidingo zokubambezeleka kokuxhumeka kwephakeji kanye nephakethe lokuminyana okukhulu, ibhodi lesifunda seliya lincipha futhi lincane, ngakho-ke idizayini yesekethe ephezulu kakhulu iyavela, futhi kufanele kulandelwe nemithetho yokwakhiwa kwemishini emincane. Reduced rise times combined with these miniaturized design rules make crosstalk noise an increasingly prominent problem, and ball grid arrays and other high-density packages themselves exacerbate crosstalk, switching noise, and ground bounce.

Izingqinamba ezilungisiwe ezikhona

Indlela yendabuko yalezi zinkinga ukuhumusha izidingo zikagesi nezenqubo zibe yimingcele yezingqinamba ezihleliwe ngesipiliyoni, amanani okuzenzakalelayo, amatafula ezinombolo, noma izindlela zokubala. Isibonelo, unjiniyela odala isekethe angaqala ngokunquma impedance elinganisiwe abese “elinganisela” ububanzi bomugqa olinganiselwe ukufeza i-impedance oyifunayo ngokususelwa kuzidingo zenqubo yokugcina, noma asebenzise itafula lokubala noma uhlelo lwezibalo ukuhlola ukuphazamiseka bese esebenza khipha izingqinamba zobude.

This approach typically requires a set of empirical data to be designed as a basic guideline for PCB designers so that they can leverage this data when designing with automatic layout and routing tools. Inkinga ngale ndlela ukuthi imininingwane yezobuciko iyisimiso esijwayelekile, futhi isikhathi esiningi ilungile, kepha kwesinye isikhathi ayisebenzi noma iholele emiphumeleni engalungile.

Masisebenzise isibonelo sokunquma impedance ngenhla ukubona iphutha elenziwa yile ndlela. Izici ezihlobene ne-impedance zifaka izakhiwo zedielectri zezinto zebhodi, ukuphakama kocingo lwethusi, ibanga eliphakathi kwezendlalelo nongqimba lomhlabathi / lwamandla, nobubanzi bolayini. Njengoba imingcele emithathu yokuqala ngokuvamile inqunywa inqubo yokukhiqiza, abaklami bavame ukusebenzisa ububanzi bomugqa ukulawula impedance. Since the distance from each line layer to the ground or power layer is different, it is clearly a mistake to use the same empirical data for each layer. This is compounded by the fact that the manufacturing process or circuit board characteristics used during development can change at any time.

Isikhathi esiningi lezi zinkinga zizovezwa esigabeni sokukhiqizwa kwesibonelo, okujwayelekile ukuthola inkinga ngokulungiswa kwebhodi lesifunda noma ukuhlela kabusha ukuxazulula ukwakheka kwebhodi. Izindleko zokwenza lokho ziphezulu, futhi ukulungiswa kulungisa izinkinga ezengeziwe ezidinga ukulungisa amaphutha ngokuqhubekayo, futhi ukulahleka kwemali engenayo ngenxa yesikhathi esibambezelekile sokumaketha kudlula kakhulu izindleko zokususa amaphutha.Almost every electronics manufacturer faces this problem, which ultimately boils down to the inability of traditional PCB design software to keep up with the realities of current electrical performance requirements. It is not as simple as empirical data on mechanical design.

Yini engasetshenziswa ukwenqabela i-PCB design?

Isixazululo: Parameterize izingqinamba

Okwamanje abathengisi be-software yokuklama bazama ukuxazulula le nkinga ngokungeza amapharamitha ezinkingeni. Isici esithuthuke kakhulu sale ndlela yikhono lokucacisa ukucaciswa kwemishini okukhombisa ngokuphelele izici ezahlukahlukene zangaphakathi zikagesi. Lapho nje lokhu sekuhlanganisiwe ekwakhiweni kwe-PCB, isoftware yokwakha ingasebenzisa lolu lwazi ukulawula ukwakheka okuzenzakalelayo nethuluzi lomzila.

When the subsequent production process changes, there is no need to redesign. The designers simply update the process characteristic parameters, and the relevant constraints can be changed automatically. Umklami angabe eseqhuba i-DRC (Design Rule Check) ukuthola ukuthi inqubo entsha yephula noma imiphi eminye imithetho yokwakhiwa nokuthola ukuthi yiziphi izici zomklamo okufanele ziguqulwe ukulungisa wonke amaphutha.

Izithiyo zingafakwa ngendlela yezisho zezibalo, kufaka phakathi iziphazamiso, ama-opharetha ahlukahlukene, ama-vectors, nezinye izingqinamba zokwakhiwa, okunikeza abaklami uhlelo oluqhutshwa umthetho olunemigomo. Constraints can even be entered as look-up tables, stored in a design file on a PCB or schematic. Izintambo ze-PCB, indawo yendawo yocingo lwethusi, namathuluzi wokuhlela alandela izingqinamba ezidalwe yilezi zimo, kanti i-DRC iqinisekisa ukuthi konke ukuklanywa kuthobela lezi zingqinamba, kufaka phakathi ububanzi bomugqa, izikhala, nezidingo zesikhala ezifana nemikhawulo yendawo nokuphakama.

Ukuphathwa okulandelanayo

Enye yezinzuzo eziphambili zezingqinamba ezenziwe ngamapharamitha ukuthi zingabekwa ebangeni. Isibonelo, umthetho wobubanzi bomugqa womhlaba ungasetshenziswa njengenkinga yomklamo kukho konke ukuklanywa. Vele, ezinye izifunda noma ama-node awakwazi ukukopisha lo mgomo, ngakho-ke umkhawulo osezingeni eliphakeme ungadlula futhi umkhawulo wezinga eliphansi ekwakhiweni okuphezulu ungamukelwa. I-Parametric Constraint Solver, Umhleli we-Constraint ovela ku-ACCEL Technologies, unikezwa amazinga aphelele ayi-7:

1. Izingqinamba zokwakhiwa kwazo zonke izinto ezingenazo ezinye izingqinamba.

2. Izithiyo zobukhosi, ezisetshenziswa ezintweni ezisezingeni elithile.

3. Imikhawulo yohlobo lweNode isebenza kuwo wonke ama-node ohlobo oluthile.

4. Node constraint: applies to a node.

5. Umkhawulo ophakathi kwezigaba: ukhombisa ukubambezeleka okuphakathi kwezinombolo zamakilasi amabili.

6. Spatial constraint, applied to all devices in a space.

7. Izithiyo zedivayisi, ezisetshenziswa kudivayisi eyodwa.

Isoftware ilandela izingqinamba ezahlukahlukene zokwakhiwa kusuka kumadivayisi ngamanye kuya kuyo yonke imithetho yokuklama, futhi ikhombisa ukuhleleka kokusebenza kwale mithetho ekwakhiweni ngendlela yemidwebo.

Example 1: Line width = F (impedance, layer spacing, dielectric constant, copper foil height). Nasi isibonelo sendlela izingqinamba ezinepharamitha ezingasetshenziswa ngayo njengemithetho yedizayini yokulawula impedance. Njengoba kushiwo ngenhla, impedance kungukusebenza kwe-dielectric njalo, ibanga kusendlalelo somugqa oseduzane, ububanzi nokuphakama kocingo lwethusi. Njengoba i-impedance edingwa ngumklamo inqunywe, lezi zinhlaka ezine zingathathwa ngokungafanele njengokuguquguqukayo okufanelekile ukubhala kabusha ifomula ye-impedance. Ezimweni eziningi, abaklami bangalawula kuphela ububanzi bomugqa.

Because of this, the constraints on line width are functions of impedance, dielectric constant, distance to the nearest line layer, and height of the copper foil. Uma ifomula ichazwa njengesithiyo sezinga eliphezulu kanye nemingcele yenqubo yokukhiqiza njengesithiyo sezinga lokuklama, isoftware izolungisa ngokuzenzakalela ububanzi bomugqa ukunxephezela lapho ungqimba lomugqa olwenzelwe luguquka. Ngokufanayo, uma ibhodi lesifunda elenzelwe likhiqizwa ngenqubo ehlukile futhi kushintshwa ukuphakama kwe-foil yethusi, imithetho efanele ezingeni lokuklama ingabalwa ngokuzenzakalela ngokushintsha amapharamitha wobude befoyili.

Example 2: Device interval = Max (default interval, F (device height, detection Angle).Inzuzo esobala yokusebenzisa zombili izingqinamba zepharamitha kanye nokuhlolwa komthetho wokuklama ukuthi indlela enamapharamitha iyaphatheka futhi ibhekwe lapho izinguquko zokwakha zenzeka. This example shows how device spacing can be determined by process characteristics and test requirements. The formula above shows that device spacing is a function of device height and detection Angle.

I-Angle yokutholwa imvamisa ingaguquguquki kulo lonke ibhodi, ngakho-ke ingachazwa ezingeni lokuklama. Lapho ubheka emshinini ohlukile, yonke idizayini ingabuyekezwa ngokufaka amanani amasha ezingeni lokuklama. Ngemuva kokuthi kufakwe amapharamitha wokusebenza komshini omusha, umklami angazi ukuthi ngabe ukwakheka kuyenzeka ngokumane usebenzise i-DRC ukubheka ukuthi ngabe izikhala zedivayisi ziyangqubuzana nenani lezikhala ezintsha, okulula kakhulu kunokuhlaziya, ukulungisa bese wenza izibalo ezinzima ngokuya kuzidingo ezintsha zesikhala.

Yini engasetshenziswa ukwenqabela i-PCB design?

Isibonelo 3: Ukuhlelwa kwento,Ngokungeziwe ekuhleleni izinto zokuqamba kanye nezingqinamba, imithetho yedizayini ingasetshenziselwa ukwakheka kwengxenye, okungukuthi, ingathola ukuthi ungabeka kuphi amadivayisi ngaphandle kokubangela amaphutha ngokuya ngemingcele. Okuqokonyiswe kusibalo 1 ukuhlangabezana nezingqinamba zomzimba (njengesikhawu nonqenqema lwesikhala sepuleti nedivayisi) indawo yendawo yamadivayisi, okuvelele okungu-2 ukuhlangabezana nezindawo zokubekwa kwezingcingo ezivinjiwe, njengobude bomugqa ophelele, umdwebo 3 ukhombisa kuphela indawo yomkhawulo wesikhala, ekugcineni, isibalo 4 kungukuhlangana kwezingxenye ezintathu zokuqala zesithombe, lokhu kungukuhlelwa kwendawo okusebenzayo, Devices placed in this region can satisfy all constraints.

What can be used to constrain PCB design？

Eqinisweni, ukukhiqiza izingqinamba ngendlela ye-modular kungathuthukisa kakhulu ukugcinwa kwayo nokusebenza kabusha. New expressions can be generated by referring to the constraint parameters of different layers in the previous stage, for example, the line width of the top layer depends on the distance of the top layer and the height of the copper wire, and the variables Temp and Diel_Const in the design level. Note that design rules are displayed in descending order, and changing a higher-level constraint immediately affects all expressions that refer to that constraint.

What can be used to constrain PCB design？

Ukusetshenziswa kabusha komklamo nemibhalo

Parametric constraints, not only can significantly improve the initial design process, and reuse of engineering change and design more useful, the constraint can be used as part of the design, system and documents, if not only in engineer or designer’s mind, so when they turn to other projects may be slowly forget. Imibhalo yesithiyo ibhala imithetho yokusebenza kukagesi okufanele ilandelwe ngenkathi kwenziwa inqubo yokwakha futhi inika abanye ithuba lokuqonda izinhloso zomklami ukuze le mithetho isetshenziswe kalula ezinqubweni ezintsha zokukhiqiza noma ishintshwe ngokuya ngezidingo zokusebenza kukagesi. Future multiplexers can also know the exact design rules and make changes by entering new process requirements without having to guess how line widths were obtained.

This article conclusion

Umhleli wesithiyo sepharamitha usiza ukwakheka kwe-PCB nokuhamba ngomgwaqo ngaphansi kwezingqinamba eziningi, futhi ngokokuqala ngqa kunika amandla isoftware yomgwaqo kanye nemithetho yedizayini ukuthi ihlolwe ngokuphelele ngezidingo eziyinkimbinkimbi zikagesi nezenqubo, kunokuthembela kokuhlangenwe nakho noma imithetho elula yokwakhiwa akusizi ngalutho. The result is a design that can achieve a one-time success, reducing or even eliminating prototype debugging.