Aquanox A4638 – Advanced Packaging Cleaning Chemistry
Aquanox A4638 – Advanced Packaging Cleaning Chemistry

Aquanox® A4638 is an engineered electronic assembly and advanced packaging cleaning agent designed to remove flux residue from flip chip and low clearance components. Aquanox A4638 is designed to remove water soluble polar flux residues and exhibits a low surface tension.

Aquanox A4638 is a product specifically designed to remove organic acid (water-soluble) based flux residues. Organic acid flux residues are highly polar and ionic in nature. The highly active flux residue must be cleaned due to its hydroscopic (water loving) nature and ability to dissolve metal ions, which can lead to dendritic growth. Organic acid fluxes are traditionally designed to be removed with hot DI water. With smaller form factors (miniaturization) and high reflow processing conditions (lead-free soldering), water soluble flux residues may oxidize and char. When this occurs, highly active flux residues may no longer be soluble in hot DI water.


Aquanox A4638 is designed with oxygenated solvents, activators, and functional activities. This slightly alkaline cleaning agent forms intermolecular attractions with polar water soluble flux residues. Oxidized organic acid flux residues generate an insoluble salt that A4638 dissolves. When comparing A4638 to other aqueous cleaning agents, this product performed exceptionally well. This is due to specifically selecting ingredients that match up to the residues left from organic acid fluxes.

Aquanox A4638 is formulated as a concentrate. The product is designed to work in spray-in-air aqueous cleaning machines. The concentration needed is typically less than 10%. The product is low in odor and contains no hazardous materials. The product has a wide material compatibility window and is specifically designed for use on printed circuit board hardware.

Head-Tech offers a turn-key solution for the cleaning process, including materials, process, and equipment. Contact us for the product bulletin and Safety Data Sheet.

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