Etch-resistant inkjet inks for manufacturing conductive patterns

Abstract

A UV curable inkjet ink includes a polymerizable composition, wherein at least 80 wt % of the polymerizable composition consists of: a) 15.0 to 70.0 wt % of an acryl amide; b) 20.0 to 75.0 wt % of a polyfunctional acrylate; and c) 1.0 to 15.0 wt % of a monofunctional (meth)acrylate containing a carboxylic acid group, a phosphoric acid group, or a phosphonic acid group; with all weight percentages (wt %) based on the total weight of the polymerizable composition.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a 371 National Stage Application of PCT / EP2015 / 071147, filed Sep. 16, 2015. This application claims the benefit of European Application No. 14186726.7, filed Sep. 29, 2014, which is incorporated by reference herein in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an etch-resistant inkjet ink and a method of manufacturing conductive patterns.[0004]2. Description of the Related Art[0005]Printed circuit boards are usually made by coating a photo resist layer on a copper sheet bonded to a non-conductive substrate, applying a temporary UV mask of a negative image of a desired conductive pattern, UV exposing the photo resist layer, removing the non-exposed photo resist layer by a developer, removing unwanted copper by etching, removing the exposed photo resist layer by an alkaline stripping bath, thereby leaving only the desired conductive copper pattern present...

AI Technical Summary

Benefits of technology

The patent text describes the creation of a special ink that can be cured quickly and resistant to etching, stripping, and flaking. This ink meets all of the requirements for a high-quality UV curable inkjet ink.

Problems solved by technology

The use of developer to remove the photo resist layer, often 50 μm thick or more, results in extra cost and chemical waste.

These volatile organic solvents lead to latency problems of inkjet print heads making reliable inkjet printing in an industrial environment process problematic.

Reducing the amount of organic solvent leads to a too high ink viscosity, because some aromatic acrylate compounds traditionally used for preparing photo resist coatings have very high viscosity.

Another problem is the flake formation in the alkaline stripping bath.

If the flake size is too large it tends to adhere to stripping equipment disturbing the smooth running of the manufacturing process.

After a while these small flakes accumulate and also start to disturb the smooth running of the manufacturing process.

This multitude of influencing factors makes it very difficult to control the flake size to a desired size.

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