Boric acid in PCBs: compliance with EU REACH regulations

Abstract

Purpose

Boric acid has been used for many years as a catalyst inhibitor and crosslinking agent to increase the glass transition temperature of epoxy resins for printed circuit boards (PCB), as well as in the glass fibre reinforcement. Recent regulation related to boric acid and its salts by the ECHA, a regulatory agency in the EU, may limit the use of these materials. The purpose of this paper is to describe the implications of this new regulation and to propose an analytical procedure that is relevant to PCB's.

Design/methodology/approach

Potential analytical procedures, including dissolution in acid and aqueous extraction followed by boric acid titration, are discussed and evaluated.

Findings

The use of acid for the digestion of prepreg, laminates and PCBs has the potential to greatly overstate the concentration of boric acid in PCBs.

Originality/value

An aqueous extraction method (German DIN 38414‐4) gives results that represent a worst‐case leaching process. It is proposed that it becomes the official analytical method for printed circuit boards in order to comply with the ECHA regulation.

Citation

Mullins, M.J., Luttrull, D.K. and Schumacher, H. (2011), "Boric acid in PCBs: compliance with EU REACH regulations", Circuit World, Vol. 37 No. 4, pp. 16-19. https://doi.org/10.1108/03056121111180857