ITW Chemtronics - Chemask ® WF Solder Masking Agent: An Advancement in Water Removable Spot Masks

Our thanks to Chemtronics for allowing us to reprint the following article.
By: Milton Davis, ITW Chemtronics


The manufacture of printed circuit boards involves many automated process steps. These processes are designed to accurately and quickly place components onto a circuit board in the minimum time required achieving the highest production quantity possible. Many chemicals are used in these steps such as soldering flux, adhesives, solder paste and temporary spot mask. While it is necessary to use these materials during various stages of the production process, residues from these chemicals can remain on the completed board and be detrimental to its performance.

Aqueous cleaning processes can be used to remove these residues. The most efficient aqueous cleaning method is the in-line, closed-loop aqueous system. This type of system involves recirculating process water through deionizing resins to remove ionic and other contaminants from the process stream, allowing the water to be reused. Though most systems are designed to remove contaminants introduced by the solder paste and flux, other materials such as protective Kapton® tape, plugs and peelable spot masks must still be removed by hand. Hand removal significantly slows down the manufacturing process.

Water-soluble spot masks were introduced to increase process efficiency and throughput. However, some masks contain materials that significantly reduce the process life of the deionizing resins. This results in more frequent replacement of resin beds, and increases manufacturing costs considerably. In response to this situation, ITW Chemtronics® has developed Chemask® WF Solder Masking Agent. Chemask WF is a temporary water filterable mask that can be removed using aqueous cleaning systems without a detrimental effect on the deionizing resin beds...

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