Από αυτά που διάβασα στο http://sheaengineering.com/Documents...for%20dist.pdf (σελ 7)
συγκράτησα τα επόμενα όσον αφορά τα no-clean και τα water whashable fluxes. Παραθέτω:
"Electrochemical activity of the flux’s residue determines the third tier of categorization: water washable or no-clean. A flux categorized as “water washable” is corrosive and must be fully cleaned off after soldering. Most water washable fluxes contain halides and strong organic acids Originally published in the proceedings of APEX, Los Angeles, California, January, 2007
that are active at room temperature and do not get fully depleted during wave solder processing. If they were to remain on the assembly after soldering, they would continue to act on the metals in the circuits, ultimately causing failure. Because the fluxes are fully cleaned after soldering, options for the formulator are not as limited as they are in no-clean products, and water washable fluxes are usually the most highly active, effective ones available. The obvious drawbacks of water washable fluxes are that they do need to be washed, which adds cost to the assembly process, and that if they are not properly washed, reliability concerns will abound.
While no-clean fluxes reduce cost by minimizing process steps, their activity levels are limited by the need for post-soldering reliability. They must be formulated to become deactivated in the wave soldering process so that their residues will be electrically acceptable. Because they are designed to fully activate and deactivate in typical soldering cycles, a cycle that is too short may not render the residues benign, and one that is too long may spend all the activators before the assembly reaches the wave. If the activators are spent during preheat, the unavailability of active materials leads to poor solder joint quality. The need to properly activate and deactivate no-clean fluxes narrows their process window when compared to water washable products. It also narrows formulation options."
Άρα, για ένα no-clean flux, που σημαίνει ΔΕΝ χρειάζεται καθάρισμα μετά το reflow, πρέπει υποχρεωτικά να γίνει ο σωστός κύκλος ενεργοποίησης-απενεργοποίησης (σωστό profile-πιστά ακολουθούμενο) ώστε τα υπολλείματα να άπενεργοποιηθούν τελείως και να μην δημιουργήσουν πρόβληματα.
Τώρα για το αν ένα flux είναι ή δεν είναι water washable κοιτάμε την κατηγορία του (μας ενδιαφέρει η δεύτερη στήλη και το Low, Moderate, High)
FLUX.JPG
(για αρχάριος καλά τα πάω?)
Απάντηση με παράθεση
Αρχικό μήνυμα από harristh
))))
) 