Cleaning flux residue removal

Spray batch and spray in-line cleaning systems for OA, no-clean, and RMA pastes and lead-free flux residues Removes all types of flux residues including lead-free in batch washing Flux residue removal in ultrasonic immersion cleaning systems requiring no sump side additives... 

The final step in the soldering process is the removal of flux residues from the completed circuit board. No-clean fluxes, as the name implies, produce residues that need not be removed from the assembly after soldering. The corrosive activators are locked up in a hard, polymerized residue. However, no-clean flux residues can potentially interfere with in-drcuit testing (probes) and inspection, degrade cosmetic appearance, inhibit rework activities, and lessen the adhesion of conformal coatings. In the event that any one of these factors becomes critical, it is best to switch to a cleanable flux than to develop a cleaning process for a no-clean flux. 

During wave soldering, most of the flux from that process is consumed or washed off the bottom side of the board when in contact with the molten solder wave. However, if no-clean flux residue seeps between the pallet and the board, it will not be removed by the wave process. Any remaining residue, if covering in-drcuit test pads, may be an impediment to proper in-circuit test probe contact. Care should be taken to minimize flux deposition for wave soldering. In terms of board design, test pads should be moved as far from intended wave-solder pallet openings as possible. 

No-clean solder flux formulations can be used for rework and repair even if the PCA was manufactnred with an aqueous clean chemistry, although the reverse is not recommended. Sometimes when a no-clean board is subjected to an aqueous cleaning, the no-clean flux residue takes on a white, gnmmy characteristic that is conducive to dendritic corrosion, which can result in soft or hard electrical shorting. Saponified aqueous cleaning can be nsed, but must be tested for effectiveness in removing the polymerized flux residue from the no-clean process and for compatibihty with the selected no-clean flux to avoid generation of corrosive byproducts. This is particularly important under connectors, area-array devices, and other components with low headroom between the underside of the body and the PWB surface. 

Trichlorotrifluoroethane (CFC 113) was widely used in the electronics industry for the removal of soldering flux residues from printed circuit boards, for degreasing components in the precision engineering industry, and for the dry cleaning of garments. 

Open top and vacuum vapor N/A degreasers for circuit assembly cleaning, and flux and ionic residue removal Batch or in-Une vapor N/A... 

Precision cleaning of electronic parts in removing no-clean and rosin flux residues in vapor degreasing and cold cleaning... 

Hand wipe and immersion N/A cleaning for removal of no-clean water soluble and rosin solder paste, white residue associated with isopropanol cleaning, and flux residues... 

Immersion, ultrasonic, and inverted spray for removing paste and adhesives, rosin flux, no-clean flux and assembly residues... 

The contamination that must be removed after the soldering process is predominantly from flux residues. The removal of flux residues from the soldered assemblies (6) is generally the most critical application. Thus it is the important fliat the assemblies are cleaned. A subsequent coating process demands a very clean and residue-free surface to assure long term stability of the coating against environmental stresses such as humidity. ... 

The substrates that have to be eleaned should be free of all kinds of residues that might have some negative influence on the functionality of the substrates. The eontamination consist predominantly of flux residues, solder paste or SMT adhesive. Another important aspect with respect to the cleaning result is the compatibility between substrates and the cleaning chemistry. It is painless to remove the contamination while destroying the substrates. 

A semi-aqueous cleaning process consists of a wash cycle using a mixture of different organic solvents followed by a rinse with deionized water. Organic contaminations, predominantly rosin flux residues, are removed through the lipophilic solvents, whereas the ionics are minimized by the polar rinse media. The different kinds of solvent formulations that are... 

The eomplete proeess in based on a closed-loop principle. Consequently, the cleaning process merely liberates those substances that are to be removed from the pe-boards (i.e., soldering flux residues). Closed-loop operation is not only advisable for eeologieal reasons, but is also a very sound economic proposition as it significantly minimizes process costs. 

High-pressure spray in air in-line cleaning processes that remove flux residues from PCBs, are often employed by manufactures to clean large quantities of boards. This still represents the most economical way to clean large quantities of PCBs. Especially for contract manufactures that are required to clean different types of PCBs, often with several different flux residues. 

Zestron VD/ Zestron Modified alcohol Flux residue and SMT adhesive removal 40°-45°C (spray-in-air stencil cleaning) N/A 170-175 27.9 N/A 62 0.76 (20 C)... 

Aquanox AA4512/ Kyzen Concentrated agent for aqueous cleaning Batch or in-line spray removal of many flux residues and uncured adhesive (5%-20% concentration range, operating range 49°C-71 °C 99-101 N/A N/A N/A N/A... 

Electrically conductive adhesives, primarily silver-filled epoxies, are finding uses as replacements for solder in surface-mounting components on printed-circuit boards and in flip-chip attachments. There are several driving forces for this application, a major one being the trend to eliminate lead and tin-lead solders because they may be health hazards. Also associated with the use of solder, is the need to eliminate ozone-depleting solvents presently used to clean and remove flux residues. Electrically conductive polymer... 

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