nkhani

Mwina pambuyo pa lamulo la Ohm, lamulo lachiwiri lodziwika bwino pa zamagetsi ndi lamulo la Moore: Chiwerengero cha transistors chomwe chingapangidwe pa dera lophatikizidwa chimawirikiza kawiri pazaka ziwiri zilizonse.Popeza kukula kwa chip kumakhalabe kofanana, izi zikutanthauza kuti ma transistors amodzi amakhala ochepa pakapita nthawi.Tayamba kuyembekezera m'badwo watsopano wa tchipisi tokhala ndi mawonekedwe ang'onoang'ono kuti uwoneke pa liwiro labwinobwino, koma ndichifukwa chiyani kupanga zinthu kukhala zazing'ono?Kodi zazing'ono nthawi zonse zimatanthauza bwino?
M'zaka zapitazi, uinjiniya wamagetsi wapita patsogolo kwambiri.M'zaka za m'ma 1920, mawayilesi apamwamba kwambiri a AM anali ndi machubu opumulira angapo, ma inductors akuluakulu angapo, ma capacitor ndi resistors, mawaya angapo ogwiritsidwa ntchito ngati tinyanga, ndi mabatire ambiri kuti agwiritse ntchito chipangizo chonsecho.Today, mukhoza Mverani oposa khumi ndi awiri nyimbo kusonkhana misonkhano pa chipangizo m'thumba lanu, ndipo mukhoza kuchita zambiri.Koma miniaturization sikuti ndi yongosunthika: ndikofunikira kwambiri kuti tikwaniritse zomwe tikuyembekezera pazida zathu lero.
Phindu limodzi lodziwikiratu la zigawo zing'onozing'ono ndikuti amakulolani kuti muphatikizepo ntchito zambiri mu voliyumu imodzi.Izi ndizofunikira makamaka pamabwalo a digito: zigawo zambiri zikutanthauza kuti mutha kuchita zambiri munthawi yofanana.Mwachitsanzo, mwachidziwitso, kuchuluka kwa chidziwitso chosinthidwa ndi purosesa ya 64-bit ndi kasanu ndi katatu kuposa ka 8-bit CPU yomwe ikuyenda pa nthawi yomweyo.Koma zimafunikanso kuwirikiza kasanu ndi katatu: zolembera, owonjezera, mabasi, ndi zina zonse ndizokulirapo kasanu ndi katatu.Chifukwa chake mungafunike chip chomwe chili chokulirapo kuwirikiza kasanu, kapena mukufuna transistor yomwe ndi yaying'ono kuwirikiza kasanu.
N'chimodzimodzinso ndi tchipisi tokumbukira: Popanga ma transistors ang'onoang'ono, mumakhala ndi malo osungira ambiri mu voliyumu yomweyo.Ma pixel omwe amawonetsedwa masiku ano amapangidwa ndi ma transistors owonda kwambiri, kotero ndizomveka kuwatsitsa ndikukwaniritsa malingaliro apamwamba.Komabe, transistor yaying'ono, imakhala yabwinoko, ndipo pali chifukwa chinanso chofunikira: magwiridwe antchito awo amakula kwambiri.Koma chifukwa chiyani kwenikweni?
Nthawi zonse mukapanga transistor, imakupatsirani zina zowonjezera kwaulere.Terminal iliyonse imakhala ndi resistor mu mndandanda.Chilichonse chomwe chimanyamula panopa chimakhalanso ndi self-inductance.Pomaliza, pali capacitance pakati pa makondakitala awiri akuyang'anizana.Zotsatira zonsezi zimawononga mphamvu ndikuchepetsa liwiro la transistor.Ma parasitic capacitance ndi ovuta kwambiri: ma transistors amafunika kulipiritsidwa ndikutulutsidwa nthawi iliyonse akayatsidwa kapena kuzimitsidwa, zomwe zimafunikira nthawi komanso zamakono kuchokera pamagetsi.
The capacitance pakati kondakitala awiri ndi ntchito ya kukula kwa thupi: ang'onoang'ono amatanthauza capacitance ang'onoang'ono.Ndipo chifukwa ma capacitor ang'onoang'ono amatanthawuza kuthamanga kwambiri komanso mphamvu zotsika, ma transistors ang'onoang'ono amatha kuthamanga pamawotchi apamwamba ndikuchotsa kutentha pang'ono potero.
Pamene mukuchepetsa kukula kwa ma transistors, capacitance sizomwe zimasintha: pali zambiri zachilendo zamakina amtundu wazinthu zomwe sizikuwonekera pazida zazikulu.Komabe, nthawi zambiri, kupanga ma transistors kukhala ochepa kumawapangitsa kukhala othamanga.Koma zinthu zamagetsi ndizoposa ma transistors.Mukachepetsa zigawo zina, zimagwira ntchito bwanji?
Nthawi zambiri, zinthu zomwe zimangokhala ngati resistors, capacitors, ndi inductors sizikhala bwino zikacheperachepera: m'njira zambiri, zitha kuipiraipira.Choncho, miniaturization wa zigawozi makamaka athe compress iwo mu voliyumu yaing'ono, potero kupulumutsa PCB danga.
Kukula kwa resistor kumatha kuchepetsedwa popanda kuwononga kwambiri.Kukaniza kwa chidutswa chazinthu kumaperekedwa ndi, komwe l ndi kutalika kwake, A ndi gawo lodutsa, ndipo ρ ndi mphamvu ya zinthuzo.Mutha kungochepetsa kutalika ndi gawo, ndikumaliza ndi chopinga chaching'ono, komabe kukhala ndi kukana komweko.Choyipa chokha ndichakuti pakuchotsa mphamvu yomweyo, zopinga zing'onozing'ono zakuthupi zimatulutsa kutentha kwambiri kuposa zopinga zazikulu.Choncho, resistors ang'onoang'ono angagwiritsidwe ntchito m'mabwalo otsika mphamvu.Gome ili likuwonetsa momwe kuchuluka kwamphamvu kwamphamvu kwa SMD resistors kumatsikira pomwe kukula kwawo kumachepa.
Masiku ano, chotsutsa chaching'ono kwambiri chomwe mungagule ndi kukula kwa metric 03015 (0.3 mm x 0.15 mm).Mphamvu zawo zovoteledwa ndi 20 mW zokha ndipo zimagwiritsidwa ntchito pamabwalo omwe amachotsa mphamvu zochepa kwambiri komanso kukula kwake.Phukusi laling'ono la metric 0201 (0.2 mm x 0.1 mm) latulutsidwa, koma silinapangidwebe.Koma ngakhale atawonekera m'kabukhu la opanga, musayembekezere kuti ali paliponse: maloboti ambiri omwe amasankha ndikuyika sakhala olondola mokwanira kuti azitha kuwagwira, chifukwa chake akhoza kukhalabe zinthu za niche.
Ma capacitor amathanso kuchepetsedwa, koma izi zichepetsa mphamvu zawo.Njira yowerengera mphamvu ya shunt capacitor ndi, pomwe A ndi malo a bolodi, d ndi mtunda pakati pawo, ndipo ε ndi dielectric constant (katundu wa zinthu zapakatikati).Ngati capacitor (makamaka chipangizo chophwanyika) ndi miniaturized, dera liyenera kuchepetsedwa, motero kuchepetsa mphamvu.Ngati mukufunabe kulongedza nafara wambiri mu voliyumu yaying'ono, njira yokhayo ndikuyika zigawo zingapo pamodzi.Chifukwa cha kupita patsogolo kwa zinthu ndi kupanga, zomwe zapanganso mafilimu opyapyala (aang'ono d) ndi ma dielectric apadera (okulirapo ε) zotheka, kukula kwa ma capacitor kwachepa kwambiri m'zaka makumi angapo zapitazi.
Capacitor yaying'ono kwambiri yomwe ilipo lero ili mu phukusi laling'ono kwambiri la metric 0201: 0.25 mm x 0.125 mm yokha.Kuthekera kwawo kumangokhala kothandizabe 100 nF, ndipo mphamvu yayikulu yogwiritsira ntchito ndi 6.3 V. Komanso, mapaketiwa ndi ang'onoang'ono kwambiri ndipo amafunikira zida zapamwamba kuti azitha kuwongolera, kuchepetsa kukhazikitsidwa kwawo kofala.
Kwa inductors, nkhaniyi ndi yovuta kwambiri.Kulowetsedwa kwa koyilo yowongoka kumaperekedwa ndi, pomwe N ndi kuchuluka kwa kutembenuka, A ndiye gawo lagawo la koyilo, l ndi kutalika kwake, ndipo μ ndizomwe zimakhazikika (permeability).Ngati miyeso yonse yachepetsedwa ndi theka, inductance idzachepetsedwanso ndi theka.Komabe, kukana kwa waya kumakhalabe kofanana: izi ndichifukwa choti kutalika ndi gawo la waya zimachepetsedwa mpaka kotala la mtengo wake woyambirira.Izi zikutanthauza kuti mumatha kukana komweko mu theka la inductance, kotero mumachepetsa khalidwe (Q) la coil.
Kachilombo kakang'ono kwambiri komwe kamapezeka pamalonda kamakhala ndi kukula kwa inchi 01005 (0.4 mm x 0.2 mm).Izi ndizokwera mpaka 56 nH ndipo zimakhala ndi kukana kwa ma ohm ochepa.Ma inductors mu phukusi laling'ono kwambiri la metric 0201 adatulutsidwa mu 2014, koma zikuwoneka kuti sanadziwitsidwepo pamsika.
Zofooka zakuthupi za ma inductors zathetsedwa pogwiritsa ntchito chodabwitsa chotchedwa dynamic inductance, chomwe chimatha kuwonedwa mumakoyilo opangidwa ndi graphene.Koma ngakhale zili choncho, ngati ingapangidwe m'njira yogulitsira malonda, ikhoza kuwonjezeka ndi 50%.Pomaliza, koyiloyo siyingachedwe bwino.Komabe, ngati dera lanu likugwira ntchito pafupipafupi, izi sizikhala vuto.Ngati chizindikiro chanu chili mumtundu wa GHz, ma coil ochepa a nH amakhala okwanira.
Izi zikutifikitsa ku chinthu china chomwe chakhala chocheperako zaka zana zapitazi koma simungazindikire nthawi yomweyo: kutalika kwa mafunde omwe timagwiritsa ntchito polumikizana.Mawayilesi oyambilira adagwiritsa ntchito ma frequency apakati-wave AM pafupifupi 1 MHz okhala ndi kutalika kwa pafupifupi 300 metres.Gulu la ma frequency a FM lomwe limakhala pa 100 MHz kapena 3 metres idakhala yotchuka mzaka za m'ma 1960, ndipo masiku ano timagwiritsa ntchito kwambiri mauthenga a 4G mozungulira 1 kapena 2 GHz (pafupifupi 20 cm).Ma frequency apamwamba amatanthauza mphamvu yotumizira zambiri.Ndi chifukwa cha miniaturization kuti tili ndi mawayilesi otsika mtengo, odalirika komanso opulumutsa mphamvu omwe amagwira ntchito pama frequency awa.
Kuchepa kwa mafunde kumatha kufooketsa tinyanga chifukwa kukula kwake kumagwirizana mwachindunji ndi kuchuluka komwe amafunikira kuti atumize kapena kulandira.Mafoni am'manja amasiku ano safuna tinyanga tating'ono tating'ono, chifukwa cha kulumikizana kwawo modzipereka pa ma frequency a GHz, pomwe mlongoti umangofunika kukhala pafupifupi centimita imodzi.Ichi ndichifukwa chake mafoni am'manja ambiri omwe amakhalabe ndi zolandila za FM amafunikira kuti muyike zomvera m'makutu musanagwiritse ntchito: wayilesi imayenera kugwiritsa ntchito waya wa m'makutu ngati mlongoti kuti ipeze mphamvu zokwanira zolumikizirana ndi mafunde atali mita imodzi.
Ponena za mabwalo olumikizidwa ndi tinyanga tating'onoting'ono, tikakhala tating'ono, timakhala zosavuta kupanga.Izi sizili chifukwa chakuti ma transistors ayamba mofulumira, komanso chifukwa zotsatira za mzere wotumizira sizilinso vuto.Mwachidule, pamene kutalika kwa waya kumadutsa gawo limodzi mwa magawo khumi a kutalika kwa mawonekedwe, muyenera kuganizira kusintha kwa gawo limodzi ndi kutalika kwake popanga dera.Pa 2.4 GHz, izi zikutanthauza kuti centimita imodzi yokha ya waya yakhudza dera lanu;ngati mugulitsa zigawo zikuluzikulu pamodzi, ndi mutu, koma ngati mutayala dera la mamilimita angapo, si vuto.
Kuneneratu za kutha kwa Lamulo la Moore, kapena kusonyeza kuti maulosi amenewa ndi olakwika mobwerezabwereza, wakhala mutu wobwerezabwereza mu utolankhani wa sayansi ndi zamakono.Chowonadi ndi chakuti Intel, Samsung, ndi TSMC, omwe akupikisana nawo atatu omwe akadali patsogolo pamasewerawa, akupitilizabe kuphatikizira zinthu zambiri pa square micrometer, ndikukonzekera kuyambitsa mibadwo ingapo ya tchipisi tabwino mtsogolomo.Ngakhale kupita patsogolo komwe apanga pagawo lililonse sikungakhale kwakukulu ngati zaka makumi awiri zapitazo, kusinthika kwa ma transistors kumapitilirabe.
Komabe, pazigawo zosiyanasiyana, tikuwoneka kuti tafika malire achilengedwe: kuzipanga kukhala zazing'ono sikuwongolera magwiridwe antchito awo, ndipo zing'onozing'ono zomwe zilipo pano ndi zazing'ono kuposa momwe ambiri amafunira.Zikuwoneka kuti palibe Lamulo la Moore pazida zodziwikiratu, koma ngati pali Lamulo la Moore, tikadakonda kuwona kuchuluka kwa munthu m'modzi atha kukankhira vuto la SMD.
Ndakhala ndikufuna kujambula chithunzi cha PTH resistor yomwe ndimagwiritsa ntchito m'ma 1970, ndikuyika chotsutsa cha SMD pamenepo, monga momwe ndikusinthira / kunja tsopano.Cholinga changa ndikupangitsa abale ndi alongo anga (palibe chimodzi mwazinthu zamagetsi) kusintha kwakukulu, kuphatikizapo ndikutha kuona mbali za ntchito yanga, (pamene maso anga akuipiraipira, manja anga akuwonjezereka Kunjenjemera).
Ndimakonda kunena, zili limodzi kapena ayi.Ndimadana kwambiri ndi "kusintha, khala bwino."Nthawi zina masanjidwe anu amagwira ntchito bwino, koma simungathenso kupeza magawo.gehena ndi chiyani chimenecho?.Lingaliro labwino ndi lingaliro labwino, ndipo ndi bwino kulisunga momwe liriri, m'malo mowongolera popanda chifukwa.Gantt
"Zowona ndizakuti makampani atatu a Intel, Samsung ndi TSMC akupikisanabe patsogolo pamasewerawa, akungotulutsa zambiri pa lalikulu micrometer,"
Zida zamagetsi ndi zazikulu komanso zodula.Mu 1971, banja wamba linali ndi mawailesi ochepa chabe, sitiriyo ndi TV.Pofika m’chaka cha 1976, makompyuta, ma calculator, mawotchi a digito ndi mawotchi anali atatuluka, zomwe zinali zazing’ono komanso zotsika mtengo kwa ogula.
Zina za miniaturization zimachokera ku mapangidwe.Ma amplifiers ogwira ntchito amalola kugwiritsa ntchito ma gyrators, omwe amatha kusintha ma inductors akuluakulu nthawi zina.Zosefera zogwira ntchito zimachotsanso ma inductors.
Zigawo zazikuluzikulu zimalimbikitsa zinthu zina: kuchepetsa dera, ndiko kuti, kuyesa kugwiritsa ntchito zigawo zochepa kwambiri kuti ntchito yozungulira igwire ntchito.Lero, sitisamala kwambiri.Mukufuna china chake chosinthira chizindikiro?Tengani amplifier ntchito.Kodi mukufuna makina aboma?Tengani mpu.ndi zina. Zigawo lero ndi zazing'ono kwenikweni, koma kwenikweni pali zigawo zambiri mkati.Chifukwa chake kukula kwa dera lanu kumawonjezeka komanso kugwiritsa ntchito mphamvu kumawonjezeka.Transistor yomwe imagwiritsidwa ntchito kutembenuza siginecha imagwiritsa ntchito mphamvu zochepa kuti ikwaniritse ntchito yomweyi poyerekeza ndi amplifier.Koma kachiwiri, miniaturization idzasamalira kugwiritsa ntchito mphamvu.Kungoti zatsopano zapita mbali ina.
Munaphonyadi zina mwazabwino zazikulu/zifukwa za kukula kocheperako: ma parasitics ochepetsedwa ndikuwonjezera mphamvu yamagetsi (yomwe ikuwoneka ngati yosagwirizana).
Kuchokera pamalingaliro othandiza, kukula kwa mawonekedwe kukafika pafupifupi 0.25u, mudzafika pamlingo wa GHz, panthawi yomwe phukusi lalikulu la SOP limayamba kutulutsa mphamvu yayikulu kwambiri *.Mawaya aatali omangirira ndi otsogolerawo pamapeto pake adzakuphani.
Pakadali pano, phukusi la QFN/BGA lasintha kwambiri potengera magwiridwe antchito.Kuphatikiza apo, mukamayika phukusi lathyathyathya motere, mumatha kukhala ndi *kutentha kwambiri* bwino komanso ma pads owonekera.
Kuphatikiza apo, Intel, Samsung, ndi TSMC atenga gawo lofunikira, koma ASML ikhoza kukhala yofunika kwambiri pamndandandawu.Zachidziwikire, izi sizingagwire ntchito ku mawu osalankhula…
Sizongochepetsa mtengo wa silicon kudzera m'mibadwo yotsatira.Zinthu zina, monga matumba.Maphukusi ang'onoang'ono amafuna zinthu zochepa komanso wcsp kapena zochepa.Phukusi laling'ono, ma PCB ang'onoang'ono kapena ma modules, ndi zina.
Nthawi zambiri ndimawona zinthu zina zamakalata, pomwe chinthu chokhacho chomwe chimayendetsa ndikuchepetsa mtengo.Kukula kwa MHz / kukumbukira ndikofanana, ntchito ya SOC ndi kakonzedwe ka pini ndizofanana.Titha kugwiritsa ntchito matekinoloje atsopano kuti tichepetse kugwiritsa ntchito mphamvu (nthawi zambiri izi sizikhala zaulere, ndiye kuti payenera kukhala zabwino zina zomwe makasitomala amasamala nazo)
Ubwino umodzi wa zigawo zikuluzikulu ndi zinthu zotsutsana ndi ma radiation.Ma transistors ang'onoang'ono amatha kutengeka kwambiri ndi kuwala kwa cosmic, muzochitika zofunika izi.Mwachitsanzo, mu mlengalenga komanso ngakhale malo owonera masitepe apamwamba.
Sindinawone chifukwa chachikulu chowonjezera liwiro.Kuthamanga kwa chizindikiro ndi pafupifupi mainchesi 8 pa nanosecond.Chifukwa chake pongochepetsa kukula, tchipisi tachangu ndizotheka.
Mungafune kuyang'ana masamu anu powerengera kusiyana kwa kuchedwa kwa kufalitsa chifukwa cha kusintha kwa ma phukusi ndi kuchepetsedwa kuzungulira (1/frequency).Kumeneko ndiko kuchepetsa kuchedwa/nthawi yamagulu.Mudzapeza kuti sizikuwoneka ngati chinthu chozungulira.
Chinthu chimodzi chomwe ndikufuna kuwonjezera ndichakuti ma IC ambiri, makamaka mapangidwe akale ndi tchipisi ta analogi, samachepetsedwa, makamaka mkati.Chifukwa cha kusintha kwa kupanga makina, phukusi lakhala laling'ono, koma ndichifukwa chakuti mapepala a DIP nthawi zambiri amakhala ndi malo ambiri otsala mkati, osati chifukwa transistors etc. akhala ang'onoang'ono.
Kuphatikiza pa vuto lopanga loboti kukhala lolondola mokwanira kuti lizitha kuthana ndi tizigawo ting'onoting'ono pamapulogalamu othamanga kwambiri, vuto lina ndikuwotcherera tinthu tating'onoting'ono.Makamaka pamene mukufunikirabe zigawo zikuluzikulu chifukwa cha mphamvu / mphamvu.Ntchito wapadera solder phala, wapadera sitepe solder phala zidindo (ikani pang'ono solder phala pakufunika, komabe kupereka zokwanira solder phala kwa zigawo zikuluzikulu) anayamba kukhala okwera mtengo kwambiri.Chifukwa chake ndikuganiza kuti pali malo otsetsereka, ndipo kupititsa patsogolo pang'ono pamlingo wa board board ndi njira yokwera mtengo komanso yotheka.Pakadali pano, mutha kuphatikiziranso kwambiri pamlingo wa silicon wafer ndikuchepetsa kuchuluka kwa zida zamagulu kuti zikhale zocheperako.
Mudzawona izi pafoni yanu.Cha m'ma 1995, ndinagula mafoni am'manja oyambirira pogulitsa garaja ndi madola angapo iliyonse.Ma IC ambiri amakhala ndi bowo.CPU yodziwika ndi NE570 compander, IC yayikulu yogwiritsidwanso ntchito.
Kenako ndinamaliza ndi mafoni osinthidwa m'manja.Pali zigawo zochepa kwambiri ndipo pafupifupi palibe chodziwika bwino.Pang'onoting'ono ya ICs, osati kuchulukana kokha komwe kumakhala kokwera, komanso mapangidwe atsopano (onani SDR) amatengedwa, omwe amachotsa zigawo zambiri zomwe poyamba zinali zofunika kwambiri.
> (Ikani phala laling'ono la solder pamene mukufunikira, komabe perekani phala lokwanira la solder pazinthu zazikulu)
Hei, ndimaganiza template ya "3D/Wave" kuti ithetse vutoli: yocheperako pomwe zigawo zing'onozing'ono zili, komanso zokulirapo pomwe gawo lamagetsi lili.
Masiku ano, zigawo za SMT ndizochepa kwambiri, mutha kugwiritsa ntchito zida zenizeni (osati 74xx ndi zinyalala zina) kupanga CPU yanu ndikusindikiza pa PCB.Kuwaza ndi LED, inu mukhoza kuwona ikugwira ntchito mu nthawi yeniyeni.
Kwa zaka zambiri, ndimayamikira kwambiri chitukuko chofulumira cha zigawo zovuta komanso zazing'ono.Amapereka kupita patsogolo kwakukulu, koma nthawi yomweyo amawonjezera zovuta zatsopano panjira yobwerezabwereza ya prototyping.
Kuthamanga ndi kuyerekezera kwa ma analogi kumathamanga kwambiri kuposa zomwe mumachita mu labotale.Pamene ma frequency a digito amakwera, PCB imakhala gawo la msonkhano.Mwachitsanzo, zotsatira za mzere wotumizira, kuchedwa kufalitsa.Prototyping ya ukadaulo uliwonse wotsogola umagwiritsidwa ntchito bwino pakumaliza kapangidwe kake, m'malo mopanga zosintha mu labotale.
Ponena za zinthu zosangalatsa, kuwunika.Ma matabwa ozungulira ndi ma modules ndi njira yothetsera kuchepa kwa zigawo ndi ma modules oyesera.
Izi zitha kupangitsa kuti zinthu zisakhale "zosangalatsa", koma ndikuganiza kuti kupangitsa kuti polojekiti yanu igwire ntchito koyamba kungakhale kopindulitsa chifukwa cha ntchito kapena zokonda.
Ndakhala ndikusintha mapangidwe ena kuchokera ku-bowo kupita ku SMD.Pangani zinthu zotsika mtengo, koma sizosangalatsa kupanga ma prototypes pamanja.Cholakwika chimodzi chaching'ono: "malo ofananira" ayenera kuwerengedwa ngati "mbale yofananira".
Ayi. Pambuyo popambana dongosolo, akatswiri ofukula zinthu zakale adzasokonezekabe ndi zomwe apeza.Ndani akudziwa, mwina m'zaka za zana la 23, Planetary Alliance itenga dongosolo latsopano…
Sindinathe kuvomereza zambiri.Kodi kukula kwa 0603 ndi chiyani?Zachidziwikire, kusunga 0603 ngati kukula kwachifumu ndi "kuyitana" kukula kwa metric 0603 0604 (kapena 0602) sikovuta, ngakhale kungakhale kolakwika mwaukadaulo (ie: kukula kofananira-osati mwanjira imeneyo) mulimonse.Olimba), koma osachepera aliyense adziwa ukadaulo womwe mukunena (metric / imperial)!
"Nthawi zambiri, zinthu zopanda pake monga zopinga, ma capacitor, ndi ma inductors sizikhala bwino mukawachepetsa."