Reflow soldering inzira iyo solder paste (musanganiswa unonamira weupfu solder uye flux) unoshandiswa kubatanidza kwenguva pfupi chinhu chimwe chete kana akati wandei emagetsi kune yavo yekusangana pads, mushure mezvo gungano rose rinoiswa mukupisa kunodzora, izvo zvinonyungudutsa solder. , kubatanidza zvachose mubatanidzwa.Kupisa kunogona kuitwa nekupfuudza gungano muovheni reflow kana pasi perambi reinfrared kana kubatanidza majoini ega nepenzura yemhepo inopisa.
Reflow soldering ndiyo yakajairika nzira yekubatanidza pamusoro pemasevhisi ekumusoro kubhodhi redunhu, kunyangwe ichikwanisa kushandiswa kuburikidza-mugomba zvikamu nekuzadza maburi ne solder paste uye kuisa chikamu chinotungamira kuburikidza nenamira.Nekuti wave soldering inogona kuve nyore uye yakachipa, reflow haiwanzo shandiswa pamabhodhi akachena kuburikidza-gomba.Kana ichishandiswa pamabhodhi ane musanganiswa weSMT uye THT zvikamu, kuburikidza-gomba reflow inobvumira iyo wave soldering nhanho kuti ibviswe mukuita kwegungano, zvichigona kudzikisa mutengo wegungano.
Chinangwa chekugadzirisa zvakare ndechekunyungudutsa solder uye kupisa nzvimbo dzakabatana, pasina kupisa uye kukuvadza zvikamu zvemagetsi.Mune yakajairwa reflow soldering process, pane kazhinji nhanho ina, dzinodaidzwa kuti "zones", imwe neimwe iine yakasarudzika yekupisa mbiri: preheat, thermal soak (inowanzo kupfupikiswa kuti ingonyura), kuyerera, uye kutonhora.
Preheat zone
Maximum slope ishamwari yetembiricha/nguva inoyera kuti tembiricha inoshanduka sei pabhodhi redunhu rakadhindwa.Iyo preheat zone ndiyo inowanzorebesa yenzvimbo uye kazhinji inomisikidza ramp-reti.Ramp-up rate inowanzova pakati pe1.0 °C ne3.0 °C pasekondi, kazhinji ichidonha pakati pe2.0 °C ne3.0 °C (4 °F kusvika 5 °F) pasekondi.Kana iyo chiyero ichipfuura iyo yakanyanya kutsetseka, kukuvadzwa kwezvikamu kubva pakupisa kwekupisa kana kuputika kunogona kuitika.
Solder paste inogona zvakare kuita yekuparadzira.Chikamu che preheat ndipo panonyungudika mupaste inotanga kubuda, uye kana chiyero chekukwira (kana tembiricha yezinga) yakanyanya kuderera, evaporation ye flux volatiles haina kukwana.
Thermal soak zone
Chikamu chechipiri, thermal soak, inowanzova 60 kusvika 120 yechipiri kuratidzwa kwekubvisa solder paste volatiles uye activation ye fluxes (ona flux), apo zvinoyerera zvinotanga oxidereduction pane chikamu chinotungamira uye mapedhi.Kunyanya kupisa tembiricha kunogona kutungamira kune solder spattering kana kubhora pamwe neoxidation yenamira, mapedhi ekunamatira uye kuguma kwechikamu.
Saizvozvo, fluxes inogona kusashanda zvizere kana tembiricha yakadzikira.Pakupera kwenzvimbo inonyorovesa kuenzana kwekupisa kwegungano rese kunodiwa nguva isati yasvika nzvimbo yekuyerera.Iyo soak mbiri inokurudzirwa kudzikisa chero delta T pakati pezvikamu zvehukuru hwakasiyana kana kana PCB gungano rakakura kwazvo.Iyo soak mbiri inokurudzirwa zvakare kuderedza voiding munzvimbo array mhando mapakeji.
Reflow zone
Chikamu chechitatu, iyo reflow zone, inonziwo "nguva iri pamusoro pekuyerera" kana "nguva pamusoro pe liquidus" (TAL), uye ndiyo chikamu chemaitiro apo tembiricha yepamusoro inosvika.Chinhu chakakosha kutariswa ndeye tembiricha yepamusoro, inova yakanyanya kubvumidzwa tembiricha yemaitiro ese.A common peak tembiricha iri 20-40 °C pamusoro liquidus.Muganho uyu anotarirwa nechikamu pagungano pamwe yakaderera kushivirira nokuda tembiricha yepamusoro (Chikamu chinonyanya kukanganiswa kupisa kupisa).Nhungamiro yakajairwa ndeyekubvisa 5 ° C kubva kune yakanyanya tembiricha iyo chikamu chiri munjodzi inogona kuchengetedza kusvika pakunyanya kupisa kwekuita.Zvakakosha kutarisa tembiricha yemaitiro kuti isapfuure muganhu uyu.
Pamusoro pezvo, tembiricha yepamusoro (inodarika 260 ° C) inogona kukonzera kukuvadzwa kwemukati kufa kwezvikamu zveSMT pamwe nekusimudzira intermetallic kukura.Sezvineiwo, tembiricha isingapise zvakakwana inogona kudzivirira paste kubva pakuyerera zvakare zvakakwana.
Nguva iri pamusoro pe liquidus (TAL), kana nguva iri pamusoro pekuyerera, inoyera kuti solder imvura yakareba sei.Iyo flux inoderedza kushushikana kwepasi pakatarisana nesimbi kuti iite metallurgical bonding, ichibvumira munhu solder poda spheres kuti abatanidze.Kana iyo nguva yeprofayiri yakadarika zvakatemwa nemugadziri, mhedzisiro inogona kunge iri nguva isati yakwana flux activation kana kushandiswa, zvinobudirira "kuomesa" paste isati yagadzirwa solder joint.Kusakwana nguva / tembiricha hukama hunokonzera kudzikira kwechiito chekuchenesa, zvichikonzera kunyorova kwakashata, kusakwana kubviswa kwe solvent uye flux, uye pamwe nekukanganisa majoini ekutengesa.
Nyanzvi dzinowanzokurudzira iyo ipfupi TAL inogoneka, zvisinei, akawanda anonamira anotsanangura shoma TAL yemasekonzi makumi matatu, kunyangwe painenge pasina chikonzero chakajeka chenguva iyoyo chaiyo.Imwe mukana ndeyekuti kune nzvimbo paPCB dzisina kuyerwa panguva yekunyorwa, uye nekudaro, kuseta nguva shoma inobvumidzwa kusvika kumasekonzi makumi matatu kunoderedza mikana yenzvimbo isina kuyerwa isingayerere zvakare.Iyo yakakwira shoma yekudzoreredza nguva inopawo muganho wekuchengeteka kubva pakuchinja kwekushisa kweovheni.Nguva yekunyorova inogara iri pasi pemasekonzi makumi matanhatu pamusoro pe liquidus.Nguva yekuwedzera pamusoro pe liquidus inogona kukonzera yakawandisa intermetallic kukura, izvo zvinogona kutungamira kune kubatana brittleness.Bhodhi uye zvikamu zvinogonawo kukuvadzwa panguva yakawedzerwa pamusoro pe liquidus, uye zvikamu zvizhinji zvine nguva yakanyatsotsanangurwa yenguva yakareba sei inogona kuratidzwa kune tembiricha pamusoro pehuwandu hwakapihwa.
Nguva shoma shoma pamusoro pe liquidus inogona kuteya zvinonyungudutsa uye kuyerera uye kugadzira mukana wekutonhora kana kugomara majoini pamwe ne solder voids.
Kutonhodza nzvimbo
Iyo yekupedzisira zone inzvimbo yekutonhodza kuti zvishoma nezvishoma itonhodze bhodhi rakagadziriswa uye kuomesa majoini e solder.Kutonhora kwakakodzera kunodzivisa kuwanda kwe intermetallic kuumbwa kana kupisa kwekushisa kune zvikamu.Tembiricha dzakajairika munzvimbo yekutonhodza dzinobva pa30–100 °C (86–212 °F).Mwero wekutonhora wekutonhora unosarudzwa kugadzira chimiro chezviyo chakanyanya kunzwika.
[1] Kusiyana nehupamhi hwekukwira-kumusoro mwero, iyo ramp-pasi mwero inowanzo furatirwa.Zvingave kuti chiyero cherampu hachinyanyi kukosha pamusoro pehumwe tembiricha, zvisinei, mutsetse unobvumidzwa wepamusoro wechero chikamu unofanirwa kushanda kunyangwe chikamu chiri kupisa kana kutonhora pasi.Kutonhodza kwe4°C/s kunowanzotaurwa.Iyo parameter yekufunga nezvayo paunenge uchiongorora maitiro emhedzisiro.
Izwi rekuti "reflow" rinoshandiswa kureva tembiricha iri pamusoro apo iyo solid mass ye solder alloy inonyatso kunyunguduka (kusiyana nekungopfava).Kana yakatonhodzwa pazasi tembiricha iyi, solder haiyerere.Yakadziya pamusoro payo zvakare, solder inoyerera zvakare-saka "kuyererazve".
Nzira dzemazuva ano dzegungano redunhu dzinoshandisa reflow soldering hairevi hazvo kuti solder ifambe kanopfuura kamwe chete.Vanovimbisa kuti solder ine granulated iri mu solder paste inodarika tembiricha yekuyerera kweiyo solder inobatanidzwa.
Thermal profiling
Iyo graphical inomiririra yeProcess Window Index yeiyo inopisa profiles.
Muindasitiri yekugadzira zvemagetsi, chiyero chenhamba, chinozivikanwa seProcess Window Index (PWI) chinoshandiswa kuyera kusimba kwekupisa kwekupisa.PWI inobatsira kuyera kuti nzira "inokwana" sei mumuganhu wekushandiswa kwemushandisi unozivikanwa seSpecification Limit.Each thermal profile inorongedzerwa kuti "inokwana" sei muhwindo rekuita (iyo yakatarwa kana kushivirira muganhu).
Pakati pehwindo rekushanda rinotsanangurwa se zero, uye yakanyanyisa kumucheto kwehwindo rekushanda se 99%. A PWI yakakura kudarika kana yakaenzana ne100% inoratidza kuti purogiramu haigadziri chigadzirwa mukati mechirevo.A PWI ye99% inoratidza kuti iyo mbiri inobata chigadzirwa mukati mezvirevo, asi inomhanya kumucheto kwehwindo rekuita.A PWI ye60% inoratidza chimiro chinoshandisa 60% yemaitiro ekutsanangurwa.Nekushandisa PWI hunhu, vagadziri vanogona kuona kuti yakawanda sei iyo hwindo rekuita rinoshandiswa neprofile yekupisa.Yakaderera PWI kukosha inoratidza chimiro chakasimba.
Kuti zvinyatsoshanda, akapatsanurwa PWI hunhu hunoverengerwa peak, mutsetse, reflow, uye soak maitiro eiyo inopisa mbiri.Kuti udzivise mukana wekuvhundutswa kwekupisa kunokanganisa kubuda, kutsetseka kwakanyanyisa muchimiro chekupisa kunofanirwa kutariswa uye kuenzaniswa.Vagadziri vanoshandisa-yakagadzirwa-software kunyatsoona uye kuderedza kukwira kwemateru.Pamusoro pezvo, software yacho inodzokorodza otomatiki hunhu hwePWI hwepamusoro, mutserendende, reflow, uye soak maitiro.Nekumisikidza hunhu hwePWI, mainjiniya anogona kuona kuti reflow soldering basa hariwedzere kana kutonhora nekukurumidza.
Nguva yekutumira: Mar-01-2022