I-MLCC Cracking ku-PCBA: Ukungena Okujulile Ezimbangela, Ukuvimbela, kanye Nemithetho Yedizayini ye-PCB

1. Isingeniso: Kungani i-MLCC Cracking Iyingozi Ebalulekile Yokuthembeka

Ukuqhekeka kwe -MLCC kungenye yezinkinga ezivame kakhulu zokuthembeka ekukhiqizweni kwe-PCB. Lezi ziphazamiso zivame ukuphunyuka ekuhlolweni kokuqala futhi zivela kuphela ngesikhathi sokujikeleza kokushisa, ukuhlolwa kokuwa, noma ukusetshenziswa kwensimu, okuholela emaphutheni angapheli, umsindo we-voltage, ugesi ovuzayo, kanye nokubuyiselwa okubizayo.

Lesi sihloko siveza uhlaka olusebenzayo lokuhlonza nokuvimbela ukuqhekeka kwe-MLCC. Ngokuqonda izimbangela zayo kanye nokusebenzisa izilawuli zedizayini nezinqubo ezifakazelwe, onjiniyela kuyo yonke imiklamo, ukukhiqiza, kanye nekhwalithi bangathuthukisa kakhulu ukuthembeka komkhiqizo futhi banciphise izindleko ezingagwemeka.

2. Ukuhlaziywa Kokwehluleka: Iyini I-MLCC Ukuqhekeka?

2.1 Ama-Flex Cracks (Okuvamile)

Ifomu lokuqhekeka kwe-Flex lapho ukugoba kwe-PCB kusebenzisa ingcindezi yokuqina ku-MLCC. Lokhu kuphuka kwezinhlangothi ngokuvamile kuqala ku-solder fillet futhi kudlulele emzimbeni we-ceramic. Izimbangela ezijwayelekile zihlanganisa ukususwa kwepaneli, ukuphatha ngesandla, ukuwohloka kwe-screw-mounting, noma amabutho ahlanganisa i-enclosure.

2.2 Ama-Thermal Cracks (Ukugeleza kabusha noma Ukungafani kwe-CTE)

Ukuqhekeka kokushisa kubangelwa ukushintsha kwezinga lokushisa okusheshayo noma ukungalingani kwe-CTE ngesikhathi sokugeleza kabusha. Kuvela njengokuqhekeka okuqondile noma okuqondile. Amaphrofayili okugeleza kabusha okungalungile noma ukushisa kwendawo ngesikhathi sokusebenza kabusha nakho kungabangela le modi yokwehluleka.

2.3 Imifantu Ebangelwa Ukudlidliza (Ukukhathala)

Ukudlidliza okuphindaphindiwe komshini kungabangela imifantu yokukhathala okuqhubekayo kuma-MLCC. Le modi ivamile ezindaweni zezimoto, zezimboni, nezinye ezinyakazisa kakhulu.

2.4 Izimpawu zikagesi zama-MLCC aqhekekile

Ukuqhekeka okuncane kubangela ukukhukhuleka kwe-capacitance noma ukwanda kwe-ESR . Ukuqhekeka okumaphakathi kuphakamisa ukuvuza kwamanje futhi kunciphisa ukumelana nokushisa (i-IR). Ukuqhekeka okukhulu kungadala ama-short circuits ngezikhathi ezithile noma unomphela, okuholela ekwehlulekeni kohlelo noma ekusebenzeni okungazinzile.

3. AmaVector Ezinhlanu Zokucindezeleka: Izimbangela Zokuhluleka kwe-MLCC

Konke ukwehluleka kokuqhekeka kwe-MLCC kusuka ekudluleleni ukubekezelela umzimba we-ceramic kuya ekucindezelekeni komshini noma okushisayo. Ukuqonda lawa ma-vector okucindezeleka kunika amandla amasu okuvimbela okuhlosiwe kuwo wonke uchungechunge lokukhiqiza.

3.1 Ukuguquguquka kwe-PCB Ngesikhathi Sokukhiqiza

Ukuguquguquka kwe-PCB ngesikhathi sokuhlukaniswa kumelela imbangela eyinhloko yokuqhekeka kwe-MLCC ezindaweni zokukhiqiza. Ukuhlukaniswa kwephaneli ye-V-cut kanye nemisebenzi yokuphuka ngesandla yethula ukugoba kwebhodi okweqile okudlulisela ingcindezi ngqo emizimbeni eqinile ye-ceramic. Ukuhlola okunzima ezimisweni ngaphandle kokusekelwa okwanele kwebhodi kuhlanganisa le ngozi, ikakhulukazi uma izindawo zokuhlola zikude namaphethelo ephaneli.

3.2 I-SMT Khetha bese Ubeka Ingcindezi Edlulele

Imishini yokubeka engalinganiswe kahle noma imibhobho yokuhlanza egugile isebenzisa amandla amaningi enziwa endaweni ngesikhathi sokubekwa kwengxenye, okubaluleke kakhulu kumasayizi amaphakheji amancane 0402 kanye no-0201. Ukuqhekeka kwe-MLCC kwenzeka lapho ingcindezi yenozili idlula amandla acindezelayo e-ceramic, okudala ukuphuka okuncane okusakazeka phakathi nemicimbi elandelayo yengcindezi eshisayo noma yokusebenza.

3.3 I-Reflow Soldering Thermal Stress

Umzimba we-ceramic kanye ne-PCB substrate inama-coefficients ahlukene wokunweba okushisayo, okwenza amandla angaphakathi okugunda ngesikhathi sesigaba sokupholisa esisheshayo sokuphinda kufakwe i-solder. Ama-MLCC amakhulu (angu-1206 nangaphezulu) abhekana nokucindezeleka okukhulu ikakhulukazi ngenxa yesisindo sawo esikhulu sokushisa nendawo ehlanganisiwe ye-solder, okwenza ukuqhekeka kwe-ceramic capacitor kube nokwenzeka kakhulu lapho amazinga okupholisa edlula u-3°C ngomzuzwana.

3.4 Ukuphinda kusetshenzwe ngesandla kanye ne-Solder eyeqile

Ukushisa kwendawo, okungalawuleki okusetshenziswa ngesikhathi sokusebenza kabusha kwenza buthaka isakhiwo se-ceramic ngokushaqeka okushisayo nokukhathala okunqwabelene. Ivolumu ye-solder eyeqile idala ukuxhumana okuqinile okudlulisa kunokuba kubambe ukucindezeleka, kuqeda umsebenzi wokunciphisa ukucindezeleka okwakhiwa kahle amafayili e-solder ahlinzeka ngokumelene nokuqhekeka kwe-MLCC.

3.5 Ingcindezi Yomsebenzisi Wokugcina

Ukwehla kwedivayisi, ukuvaleka kuqina kakhulu ngetorque yesikulufu eseqile, nokuguquguquka komkhiqizo phakathi nokusetshenziswa kwenkundla okuvamile kumelela i-vector yokugcina yokucindezeleka. Izinto zikagesi zabathengi namadivayisi aphathwayo abhekene nengozi enkulu kakhulu, njengoba imijikelezo yokushaqeka ephindaphindwayo isheshisa ukusakazeka kokuqhekeka ezingxenyeni ezivele zinengcindezi kusukela kunqubo yokukhiqiza.

4. I-Assembly Floor Defense: Inqubo kanye Nezixazululo ze-QA Zokuqeda Ukuqhekeka kwe-MLCC

Ukulawulwa kwenqubo yokukhiqiza kunikeza umugqa wokuqala wokuzivikela ngokumelene nokuqhekeka kwe-ceramic capacitor. Ukusebenzisa ukuthuthukiswa kwenqubo eqondisiwe kuyo yonke imisebenzi yokuhlukanisa, ukubekwa, kanye nokugeleza kabusha kunciphisa ngokumangazayo izilinganiso zokuhluleka.

4.1 Izindlela Ezinhle Zokuhlukanisa

Ukugwema ukusikeka kwe-V okujulile eduze kwezingxenye ezinkulu kanye nokushintshela ekuhlukaniseni okusekelwe kumzila kunciphisa ukuguquguquka kwebhodi ngesikhathi sokuhlukaniswa kwamaphaneli. Amarutha adala ingcindezi ephansi kakhulu kunemisebenzi yokugunda noma yokuphuka, enciphisa ingozi yokuqhekeka ye-MLCC ngokufika ku-80% ezifundweni ezilawulwayo. Ukusekela imiphetho ye-PCB ngokulungiswa okuklanywe kahle ngesikhathi sokuhlukaniswa kuvimbela ukuchezuka kwesikhungo okudlulisela ingcindezi ezingxenyeni.

4.2 Ukulawula Ingcindezi Yokubekwa Kwe-SMT

Ukuqinisekisa ukuthi ukulinganisa kwamandla omlomo womlomo kuhlala ngaphakathi kokucaciswa (imvamisa ama-Newtons angu-1-3) kanye nokusebenzisa ukuqinisekiswa okujwayelekile kuvimbela ingcindezi yokubeka ngokweqile. Amasistimu okulinganisa ubude azenzakalelayo athola imibhobho egugile futhi avimbele ukuqhekeka kwe-MLCC ekulayishweni okucindezelwayo, okubaluleke kakhulu njengoba osayizi bephakheji behla futhi imizimba yobumba iba ntekenteke kakhulu.

4.3 Ukuthuthukiswa Kwephrofayela Yokugeleza Kabusha

Ukuthuthukisa izinga lerempu yokupholisa kuvumela ukukhululwa kancane kancane kwengcindezi njengoba umhlangano ubuyela kuzinga lokushisa elizungezile, kunciphisa ukuqhekeka kwe-ceramic capacitor ebangelwa ukushisa. Izingxenye ezinkulu (ezingu-1210 nangaphezulu) zizuza ezinyathelweni zokushisa ezandisiwe ezinciphisa ukuthambekela okushisayo kuwo wonke umzimba we-ceramic, okugcina ingcindezi ephezulu ngaphansi kwemikhawulo yokuphuka.

4.4 Imihlahlandlela Yokuphatha kanye Nokusetshenzwa Kabusha

Ukunciphisa imvamisa yokusebenza kabusha ngokusebenzisa isivuno esithuthukisiwe sokudlula kuqala kususa imijikelezo enqwabelene yokucindezeleka okushisayo. Lapho ukusetshenzwa kabusha kuba kudingekile, amapuleti okushisa angaphambili anciphisa ama-gradients ashisayo ngaphambi kokufaka ukushisa kwe-soldering iron, ukuvimbela ukushaqeka kwendawo okushisayo okubangela ukuqhekeka kwe-MLCC kwezinye izingxenye ezinempilo.

5. Ikhithi Yamathuluzi Yomklami: Imihlahlandlela Yesakhiwo Sokukhulula Ingcindezi

Izinqumo zesakhiwo se-PCB zinquma ngokuyisisekelo ukuthambekela kokuqhekeka kwe-MLCC. Ukusebenzisa imithetho yokuklama yokunciphisa ukucindezeleka phakathi nesigaba sokuhlela kuvimbela ukwehluleka ngempumelelo kunanoma yikuphi ukulawula inqubo yokwehla komfula.

5.1 Beka i-MLCC Perpendicular to Board Flex Direction

Ukuvumelanisa ubude bomzimba we -capacitor ngokuqondile ne-axis ende yebhodi noma isiqondiso esiguquguqukayo esaziwayo kuqondisa ukucindezeleka ngosayizi omfushane noqinile wengxenye. Lo mthetho olula wokuqondiswa unciphisa ingozi yokuqhekeka kwe-capacitor ye-ceramic ngo-60% uma kuqhathaniswa nokuqondaniswa okuhambisanayo, njengoba isilinganiso sesici somzimba we-ceramic sidala izici zamandla ahlukile.

5.2 Sebenzisa Ama-Parallel Arrays Esikhundleni Se-Single Large MLCC

Ukushintsha i-capacitor eyodwa enkulu (efana ne-1×22µF, 1206) ngezincanyana eziningi (ezifana ne-2×10µF, 0603) kusabalalisa ingcindezi eshisayo neyomshini kuzo zonke izingxenye eziningi ngenkathi kuthuthukiswa ukusebenza kwe-DC-bias. Imizimba emincane ye-ceramic inokubekezelela ingcindezi ephezulu ngokwemvelo ngokuqhathaniswa nevolumu yayo, okwenza ukuqhekeka kwe-MLCC kube mancane amathuba okuba ngaphansi kwezimo ezifanayo zokulayisha.

5.3 Gcina i-MLCC Ikude Namaphoyinti Okugxilisa Ingcindezi

Ukugcina imvume okungenani engu-5mm kusukela ekusikeni kwe-V, izimbobo zezikulufu, izikhala ezifakwayo, namaphethelo ebhodi kuvimbela ukudluliselwa kokugxilisa ingqondo emizimbeni yobumba. Amathebhu wokunqamula kanye namashaneli omzila wephaneli adala ikakhulukazi izinkundla zengcindezi zasendaweni eziqinisekisa ukuqhekeka kwe-MLCC uma izingxenye zibekwe eduze.

5.4 Khulisa Isikhala Somhlaba kanye Nokulawula Imisipha Ye-Solder

Ukuklama amaphethini omhlaba amakhudlwana kunika amandla amafayili e-solder aqinile, amise okwe-cove asebenza njengezinqamuli zengcindezi phakathi komzimba oqinile we-ceramic kanye ne-PCB eguqukayo. Ijiyomethri yefillet efanele idonsa ukucindezeleka komshini ngokusebenzisa ukuguqulwa okulawulwayo, ivimbele ukudluliswa kwengcindezi okuqondile okubangela ukuqhekeka kwe-ceramic capacitor.

5.5 Cabanga nge-Soft Termination MLCCs

Ngezinhlelo zokusebenza ezinokwethenjelwa okuphezulu noma ezinengcindezi ephezulu ezihlanganisa ezezimoto kanye ne-aerospace, ukucacisa ama-MLCC anezendlalelo ze-polymer ngaphakathi kokunqanyulwa kunikeza ukumuncwa kwengcindezi okwengeziwe. Izingxenye zokunqanyulwa okuthambile zehlisa ubungozi bokuqhekeka kwe-MLCC ngo-70% ekuhlolweni kokuguquguquka kwebhodi uma kuqhathaniswa nokunqanyulwa okujwayelekile okuqinile, okufakazela izindleko zazo zeprimiyamu ezinhlelweni ezibucayi.

6. Ukuqinisekisa kanye Nokuhlolwa: Ukuhlola Izinqubo Zokuthembela Kwe-Crack-Free

Izinqubo zokuhlola ezibanzi ziqinisekisa ukumelana nokuqhekeka kwe-MLCC ngaphambi kokuba imikhiqizo ifinyelele amakhasimende. Ukusebenzisa ukuhlolwa kwezendlalelo eziningi nokuhlola ingcindezi kuthola ukwehluleka ngesikhathi sokuqinisekisa okulawulwayo kunembuyiselo yenkambu ebizayo.

6.1 Ukuhlola Okungabhubhisi

Ukuhlolwa kwe-X-ray kunikeza ukuqinisekiswa kobuqotho besakhiwo okubalulekile kwamalunga e-solder kanye nokutholwa kwemifantu yangaphakathi, ikakhulukazi okuphoqelekile kumaphrojekthi anokwethenjelwa kakhulu lapho ukwehluleka kokuqhekeka kwe-capacitor ye-ceramic kunemiphumela emibi kakhulu. Ukuhlolwa okubonakalayo kugcwalisa i-X-ray ngokuhlola ukuma kwe-fillet kanye nokuhlonza i-solder eningi edala izindlela zokudlulisela ukucindezeleka okuqinile.

6.2 Izindlela Zokuhlola Ugesi

Ukuqapha ukumelana nokufakwa kwe-insulation (IR) kanye nokuvuza kwamanje kuveza ukuqhekeka okuncane kwe-MLCC ngaphambi kokuthi kwenzeke ukwehluleka okuyinhlekelele. Ukuncipha kwe-IR kancane noma ukuvuza okuphakeme kwamanje kubonisa ukusakazeka kokuqhekeka okuqhubekayo, okuvumela ukungenelela ngokushintsha ingxenye ngesikhathi sokukhiqiza kunenkonzo yasensimini.

6.3 Ukuhlolwa Kwebhodi Le-Flex Stress

Ukusebenzisa izindinganiso ze-IPC-9702 board flex test kuqinisekisa ukuklama nokubekwa kwengxenye ngaphansi kwezimo zokucindezeleka ezilawulwayo. Ukuhlolwa kokugoba okunamaphoyinti amathathu kulinganisa imikhawulo yokuqhekeka kwe-ceramic capacitor kumadizayini athile ebhodi, okuvumela ukuthuthukiswa kwedizayini ngaphambi kokuzibophezela ekukhiqizweni kwevolumu.

7. Izincomo Ezifingqiwe kanye Nezisebenzayo

Ngokuhlangenwe nakho kwami, imbangela eyinhloko cishe yonke i-MLCC yokuqhekeka ingcindezi engalawuleki yemishini noma eshisayo. Ukuvimbela lokhu kwehluleka kudinga ukuphatha ukwethembeka kwe-MLCC njengenkinga yeleveli yesistimu—elawulwa ngezinketho zedizayini, izindlela zokuhlanganisa, nokuziphatha kokuhlola.

• I-Orient MLCCs perpendicular to the primary flex direction ye-PCB. Ngikubonile lokhu kushintsha kokubeka okulula kunciphisa kakhulu imifantu e-flex-induced, ikakhulukazi emabhodini anokulungiswa komshini noma ukuphatha ngesandla.
• Sebenzisa amalungu afanayo afanayo ama-MLCC amancane esikhundleni se-capacitor eyodwa enkulu. Ngokusekelwe ekuhlaziyweni kokwehluleka okuningi engisebenze kukho, ama-capacitor amancane asabalalisa ingcindezi kangcono kakhulu futhi abekezelela ukugoba.
• Gwema ukuhlukaniswa kwe-V-cut eduze nezingxenye ezizwelayo. Kusuka kulokho engikubonile esitezi sokukhiqiza, ama-V-cut ahlala ethula uhlobo oluphakeme kakhulu ngesikhathi sokucula. I-depanelization esekelwe kumzila ikhiqiza amacala ambalwa kakhulu okuqhekeka.
• Gcina amaphrofayili okushisa okugeleza kabusha alawulwayo. Ukushisa okusheshayo noma ukupholisa kuyisandulela esivamile sokuqhekeka okushisayo. Iphrofayela ezinzile, enezimpawu ezinhle inciphisa lobu bungozi kakhulu.
• Nciphisa ukuphatha ibhodi nokugoba okungalawuleki ngesikhathi somhlangano. Ngokuhamba kweminyaka, ngithole ukuthi imithwalo encane, ephindaphindiwe yokubamba ivame ukudala ama-microcracks avele abonakale ngesikhathi sokuhlolwa kokwethembeka.

Ukusebenzisa lezi zinyathelo ngokungaguquki kuyo yonke idizayini, ukukhiqiza, nokulawulwa kwekhwalithi kufakazele ukuthi kuyindlela enokwethenjelwa kakhulu yokunciphisa ukuqhekeka kwe-MLCC nokuvimbela izinkinga zokwethenjelwa komfula.