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1. Kev tshem tawm oxide

Tshem tawm cov tooj liab oxide (CuO, Cu₂O) ntawm PCB pads thiab cov khoom siv lead ua kom cov tooj liab tshiab, reactive tooj liab raug rau cov molten solder. Yog tsis muaj cov kauj ruam no, lub solder tsis tuaj yeem ntub qhov chaw thiab dewetting los yog tsis yog -wetting defects.

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2. Re-Kev tiv thaiv oxidation

Tom qab ntxuav qhov chaw, cov flux yuav tsum tiv thaiv re-oxidation thaum lub sij hawm cua sov (preheat cheeb tsam, 150-200 degree) ua ntej lub solder melts. Lub activator yuav tsum nyob twj ywm ntawm qhov kub thiab txias thaum lub tsheb flux evaporates.

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3. Solder wetting nce qib

Txo qhov nro ntawm lub molten solder thaum lub sij hawm reflow ncov (230-260℃rau SAC alloys) kom nws kis tusyees nyob rau hauv lub ncoo thiab wicks li tivthaiv, ua kom ntseeg tau cov fillet geometry thiab sib koom ua ke lub zog.

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4. Muaj kev nyab xeeb, ruaj khov residue (tsis muaj- huv)

After reflow, the residue must be electrically non-conductive (SIR >10⁸ Ω), tsis yog -corrosive rau tooj liab thiab solder, av noo- ruaj khov, thiab lub cev ruaj khov nyob rau hauv thermal cycling ntawm cov khoom sib dhos ua haujlwm lub neej.

🔬 Kauj Ruam 1: Thermal decomposition ntawm tooj liab oxide (230-260 degree)

Nyob rau hauv reflow ncov kub, tooj liab oxide undergoes ib feem ntawm thermal txo, ua rau cov oxide ntau raug rau kev sib koom tes nres:

4 CuO → 2 Cu₂O + O₂ (ib nrab ntawm 230–260 degree)

🔬 Kauj Ruam 2: Kev sib koom tes ntawm Alkanolamine nrog Cu²⁺ thiab Cu⁺

Cov amine nitrogen thiab hydroxyl oxygen ntawm alkanolamine ua haujlwm nrog tooj liab ions ntawm oxide nto, tsim cov tooj liab soluble -alkanolamine complexes. Qhov no tshem tawm cov tooj liab ions los ntawm cov oxide lattice, ua kom yaj cov oxide zaj duab xis. Cov tshuaj tiv thaiv tshwm sim sai sai ntawm 200-260℃txawm rau tertiary amines uas tsis reactive ntawm ambient kub - lub thermal zog overcomes lub activation barrier uas tiv thaiv cov tshuaj tiv thaiv ntawm chav tsev kub.

🔬 Kauj Ruam 3: Kev ua kom tsis zoo thiab ua rau cov tooj liab tshiab

Cov tooj liab soluble-alkanolamine complex migrates deb ntawm hlau nto. Thaum lub ncov reflow kub, nws decomposes - tso cov alkanolamine (uas ib nrab volatilizes, tshwj xeeb tshaj yog DMEA nrog bp 135℃) thiab lub freshly nthuav tooj liab nto yog tam sim ntawd wetted los ntawm molten solder los ntawm metallurgical bonding cov tshuaj tiv thaiv.

DMEA - volatility kom zoo dua (bp 135 degree)

• Pib volatilize thaum lub sij hawm preheat cheeb tsam (150-200 degree) - activator yog feem ntau concentrated nyob rau saum npoo thaum kub ramp, ces tawm ncej-reflow
• Cov ntawv tshaj tawm -reflow residue muaj cov ntsiab lus ionic qis dua thiab kev ua haujlwm zoo SIR
• Tsawg amine tsw hauv cov khoom sib dhos
• Qhov zoo tshaj plaws rau:SMT reflow solder muab tshuaj txhuam; qis-residue tsis muaj- ntxuav flux; aerospace thiab kev kho mob electronics qhov twg tsawg kawg nkaus residue tseem ceeb heev

DEAE - kev ruaj ntseg zoo (bp 162 degree)

• Tseem nyob rau hauv cov kua flux theem thoob plaws ntau ntawm thaj chaw preheat - tshem tawm oxide nyob rau hauv lub qhov rais kub
• Kev ua tau zoo dua ntawm cov oxidized hnyav lossis cov laus laus uas yuav tsum tau ncua sijhawm nyob hauv flux
• Ntau ruaj khov nyob rau hauv flux concentrate cia - tsawg evaporation los ntawm qhib flux da dej
• Qhov zoo tshaj plaws rau:Selective soldering flux; yoj soldering flux; nyuaj-rau- solder nto; general-lub hom phiaj tsis muaj- ua kua dej huv

⚖️ Siv qhov tsawg kawg nkaus ua tau zoo alkanolamine concentration

0.5-3.0% DMEA lossis DEAE los ntawm qhov hnyav. Txhua feem pua ​​​​nce ntxiv oxide tshem tawm kev ua si tab sis kuj ua rau cov residue ionic muaj peev xwm. Pib qis thiab nce tsuas yog tias kev ua haujlwm ntub dej tsis txaus ntawm lub hom phiaj substrate.

🔗 Xaiv cov organic acid co- activators uas decompose ntawm reflow kub

Succinic acid, adipic acid, thiab glutaric acid yuav tsum decarboxylate los yog decompose thaum lub sij hawm reflow peak - tawm tsis muaj residual acid rau amine ntsev tsim nyob rau hauv lub post-reflow residue. Match acid decomposition kub (feem ntau 200-265 degree) rau koj reflow ncov kub.

🌊 Siv lub tshuab tsis yog -hygroscopic resin system

Ntuj rosin (WW, WG qib) los yog hloov rosin (hydrogenated, polymerized) nrog tsawg noo noo nqus. Tsis txhob siv cov resins uas muaj cov kua qaub ntau dhau - cov no ua rau cov ionic residue tsis hais cov amine activator xaiv.

🛡️ Ntxiv benzotriazole (BTA) ua tooj liab nto inhibitor

BTA ntawm 0.05-0.2% tsim ib qho kev tiv thaiv monolayer rau ntawm tooj liab nto tom qab reflow, muab ntev - tiv thaiv corrosion nyob rau hauv cov av ntub. Tau tshaj DMEA thiab DEAE ntawm cov flux formulation concentrations.

🔥 SMT reflow (kub muab tshuaj txhuam flux)

Flux sib xyaw nrog cov hmoov txhuam thiab luam tawm rau hauv PCB pads. Yuav tsum nyob twj ywm luam tau rau 8+ teev, tsis txhob tawg ua ntej reflow, tsis ua rau lub pob solder, qhib nyob rau hauv lub 60-90 thib ob reflow qhov rais, thiab tawm tsawg kawg uas tsis yog -tacky residue.

DMEA lub luag haujlwm:0.5-1.5% nyob rau hauv solder paste flux. Ib nrab volatility ntawm preheat pab txo cov pob balling. Fast diffusion los ntawm flux matrix xyuas kom muaj kev sib cuag nrog oxide nto ua ntej solder melting.

💧 Selective soldering (kua flux)

Siv hauv zos mus rau hauv - qhov sib xyaw ua ke ua ntej tam sim ntawd ua ntej lub qhov taub los yog mini -wave. Yuav tsum ntub dej sai sai (5–25 cP), nkag mus rau hauv - lub qhov chim, nyob twj ywm thaum lub sij hawm 2-8 thib ob lub sij hawm sib cuag, thiab tsis txhob kis kab mob SMT cov khoom nyob ib sab.

DEAE lub luag haujlwm:1.0-2.5% hauv IPA lossis cawv cawv. Siab dua bp (162 degree) tiv thaiv evaporation ntxov ntxov ntawm daim ntawv thov flux thiab solder hu (5-15 vib nas this). Kev ua haujlwm ruaj khov ua kom lub thoob ntim tau txawm tias nyob ntawm qee qhov oxidized txhuas qhov chaw.

⚠️ DMEA tuav hauv cov ntawv thov flux

• Flash point 43℃(Flam. Liq. 3) - khaws cia deb ntawm qhov hluav taws kub; anti- khoom siv static dispensing yuav tsum tau
• DMEA evaporates los ntawm cov thawv qhib - kom nruj nruj; tshawb xyuas cov concentration ib ntus hauv lub da dej flux
• IPA-raws li flux concentrates yog flammable - Chav kawm 3 kev cia khoom siv rau kev npaj ua ntej-rau-siv flux
• Cov tub yees cia txias (5-10 degree) txuas lub neej txee ntawm cov tshuaj nplaum uas muaj DMEA activator

⚠️ DEAE tuav hauv cov ntawv thov flux

• Flash point 60℃- tseem Flam. Liq. 3 tab sis dav dav kev nyab xeeb tshaj li DMEA
• Tsawg vapor siab - ntau ruaj khov nyob rau hauv qhib flux da dej; tsawg concentration drift dhau kev hloov pauv ntau lawm
• Tau tshaj IPA thiab glycol ether carrier solvents
• Txee lub neej ntawm DEAE-raws li flux concentrate: 12-18 lub hlis nyob rau hauv kaw amber iav los yog HDPE ntim ntawm chav tsev kub

Q: Dab tsi yog qhov feem ntau alkanolamine concentration nyob rau hauv kev lag luam tsis muaj -huv tshuaj txhuam cov tshuaj txhuam hniav?

Nyob rau hauv ib txwm tsis muaj -cov tshuaj txhuam huv huv (flux cov ntsiab lus kwv yees li 10-15% ntawm tag nrho cov muab tshuaj hnyav), cov alkanolamine activator feem ntau yog 0.5-2.0% ntawm tag nrho cov flux hnyav - sib npaug rau 0.05-0.30% ntawm tag nrho cov muab tshuaj txhuam, lossis kwv yees li 5000-3.000 ppm. Rau cov dej nthwv dej thiab xaiv cov kua nplaum uas tau diluted hauv cov cab cab (feem ntau 2-5% flux solids hauv IPA), cov alkanolamine hauv qhov npaj tau-rau- siv flux yog 0.05-0.15% los ntawm qhov hnyav. Qhov tseeb concentration yog sib npaug tiv thaiv cov organic acid co- qib activator (feem ntau 1-5% ntawm flux) kom paub tseeb tias oxide tshem tawm txaus yam tsis muaj kev cuam tshuam tom qab-reflow SIR kev ua tau zoo.

Q: Kuv puas tuaj yeem siv DMEA lossis DEAE hauv halide-muaj (ORL1 chav kawm) flux formulations?

Yog - ob qho tib si tau ua tiav nrog halide- muaj cov qauv flux. Nyob rau hauv me me activated halide- muaj cov fluxes, alkanolamine muab lub hauv paus ua kom lub cev thaum ib qho me me ntawm halide activator (feem ntau 0.1-0.5%) muab cov aggressive thawj oxide cuam tshuam ntawm nyuaj - rau - solder nto. Kev sib xyaw ua ke tuaj yeem ua tiav dhau IPC-J-STD-004 ORL1 kev faib tawm nrog kev ntub dej zoo dua rau ntawm qhov chaw oxidized dua li halide- cov qauv dawb ib leeg. Txawm li cas los xij, cov ntsiab lus ionic ntau dua ntawm cov seem yuav tsum tau ua tib zoo soj ntsuam SIR - tshwj xeeb tshaj yog nyob rau hauv qhov chaw ntub dej.

Q: Yuav ua li cas alkanolamine flux ua rau OSP (organic solderability preservative) tiav PCBs?

DMEA thiab DEAE-raws li fluxes ua tau zoo nyob rau hauv thawj- dhau OSP - kev sib koom ua ke chemistry tawm tsam CuO hauv qab cov txheej txheem organic. Thib ob -pass (rework) ntawm OSP tuaj yeem nyuaj dua vim tias OSP yuav muaj qee qhov kev puas tsuaj thaum thawj lub voj voog rov qab. Rau ntau- dhau OSP pawg thawj coj saib, qhov siab dua me ntsis alkanolamine concentration (1.5–2.5% DEAE) lossis ntxiv cov halide activator tsis muaj zog ua kom qhov thib ob- dhau kev ntseeg tau. DMEA-raws li flux yog qhov nyiam me ntsis rau OSP tshaj ENIG (electroless nickel immersion kub) vim muaj kev pheej hmoo tsawg dua ntawm nickel complexation ntawm qhov kub siab.

Q: Puas yog DMEA lossis DEAE siv tau nrog cov txheej txheem txheej txheem uas tsis muaj -cov dej huv huv?

Acrylic conformal coatings feem ntau qhia zoo adhesion tshaj DMEA-raws li flux residues vim hais tias cov residue tsis yog -polar thiab tsis yog -tacky. Silicone coatings yuav qhia tau qee qhov teeb meem adhesion nrog rosin-raws li residues. Txoj kev nyab xeeb tshaj plaws rau kev nyab xeeb- daim ntawv thov tseem ceeb (aerospace, kho mob) yog ntxuav lub rooj tsavxwm ua ntej txheej txheej txawm tias tsis muaj - huv huv. Yog tias txheej txheej tsis muaj -cov seem huv si, txheeb xyuas kev sib raug zoo nrog koj qhov tshwj xeeb flux/coating ua ke siv IPC-A-610 adhesion thiab SIR kuaj raws li koj qhov kev tsim nyog raws tu qauv.

Q: Lub txee lub neej ntawm DMEA thiab DEAE yog dab tsi yog cov khoom siv raw rau kev tsim flux?

Ob leeg DMEA thiab DEAE muaj lub neej txee ntawm 24 lub hlis hauv cov thawv ntim kom zoo khaws cia hauv qab 30℃thiab deb ntawm lub teeb, oxidizing cov neeg ua haujlwm, thiab cov kua qaub muaj zog. DMEA yuav tsum tau muab khaws cia rau hauv cov thawv kaw nruj nreem muab nws cov pa siab dua - ib nrab evaporation los ntawm lub nruas kaw ntom ntom yuav ua rau kom muaj zog thiab hloov pauv qhov tseeb ntawm flux formulation. Txheeb xyuas qhov concentration los ntawm GC los yog acid-base titration ua ntej siv yog tias khaws cia ntev dua 12 lub hlis. Ob leeg yuav tsum tau muab cia rau hauv stainless hlau, HDPE, lossis iav ntim - kom tsis txhob muaj tooj liab, tooj dag, thiab zinc alloys.