Becoming REACH Compliant: Is your Pure Gold Pure Enough? Part 2 of 2

August 25,2016

In part 1 of this series, we discussed diarsenic pentoxide (As2O5), a substance that was used as a grain refiner in pure gold electroplating for decades, but that has been banned since May 2015 under REACH. The need to become REACH compliant created demand for an arsenic-free, lead-free pure gold electroplating solution; something that one might anticipate taking years of research to achieve, but that is now commercially available in the EU.

Pure gold, also known as soft gold or wire-bondable gold, is primarily used as a contact for wire bonding. This is in contrast to hard gold, which includes nickel or cobalt additives to improve hardness and wear for applications that require those properties. Pure gold contacts are preferred for wire bonding because they provide high electrical conductivity, excellent corrosion resistance, and reliable solderability.

Electrolytic pure gold has historically achieved these desirable properties as a result of grain refiners containing As2O5 and Pb; compounds that help create an optimum microstructure. The problem is that As2O5 is on the REACH Annex XIV authorization list, and RoHS severely restricts the use of Pb in electronics.

Nearly all pure gold electrolytes on the market contain these banned substances, forcing customers to purchase exemption permits to use them in specific applications. This creates an added burden, and there is no guarantee that such exemptions will continue to be granted, putting manufacturers at risk. The market is therefore primed for an As-free, Pb-free solution.>

In part 1 of this series, we discussed diarsenic pentoxide (As2O5), a substance that was used as a grain refiner in pure gold electroplating for decades, but that has been banned since May 2015 under REACH. The need to become REACH compliant created demand for an arsenic-free, lead-free pure gold electroplating solution; something that one might anticipate taking years of research to achieve, but that is now commercially available in the EU.

Pure gold, also known as soft gold or wire-bondable gold, is primarily used as a contact for wire bonding. This is in contrast to hard gold, which includes nickel or cobalt additives to improve hardness and wear for applications that require those properties. Pure gold contacts are preferred for wire bonding because they provide high electrical conductivity, excellent corrosion resistance, and reliable solderability.

Electrolytic pure gold has historically achieved these desirable properties as a result of grain refiners containing As2O5 and Pb; compounds that help create an optimum microstructure. The problem is that As2O5 is on the REACH Annex XIV authorization list, and RoHS severely restricts the use of Pb in electronics.

Nearly all pure gold electrolytes on the market contain these banned substances, forcing customers to purchase exemption permits to use them in specific applications. This creates an added burden, and there is no guarantee that such exemptions will continue to be granted, putting manufacturers at risk. The market is therefore primed for an As-free, Pb-free solution.>

As a leading supplier of pure gold to the semiconductor packaging industry, Dow took a proactive stance and began developing an As-free plating bath well ahead of the REACH sunset date. Still, it took an additional year after the May 2015 sunset date for the product to be ready for commercial use. This underscores the need to begin research on REACH compliant products as early as possible, when potentially banned substances are merely included in the candidate list.

Dow is developing solutions to address these emerging requirements. Specifically, Dow’s AURONAL™ BGA LF electrolytic gold product line is completely free of As and Pb, yet maintains desirable wire bonding properties. The AURONAL™ BGA LF electrolytic gold plating process does still include the use of gold potassium cyanide, as do all other pure gold electrolytes on the market. While this requires appropriate safety procedures during processing, it is possible to treat the effluent to avoid leaching cyanide into the waste stream.

As OEMs look to achieving REACH compliance to continue selling their products in the EU without having to go through the exemption process, they need to thoroughly evaluate their complete supply chains. Electrolytic gold plating is just one example application where a suitable alternative to standard commercial products exists, allowing manufacturers to meet REACH requirements while maintaining the quality and reliability their customers expect.

As a leading supplier of pure gold to the semiconductor packaging industry, Dow took a proactive stance and began developing an As-free plating bath well ahead of the REACH sunset date. Still, it took an additional year after the May 2015 sunset date for the product to be ready for commercial use. This underscores the need to begin research on REACH compliant products as early as possible, when potentially banned substances are merely included in the candidate list.

Dow is developing solutions to address these emerging requirements. Specifically, Dow’s AURONAL™ BGA LF electrolytic gold product line is completely free of As and Pb, yet maintains desirable wire bonding properties. The AURONAL™ BGA LF electrolytic gold plating process does still include the use of gold potassium cyanide, as do all other pure gold electrolytes on the market. While this requires appropriate safety procedures during processing, it is possible to treat the effluent to avoid leaching cyanide into the waste stream.

As OEMs look to achieving REACH compliance to continue selling their products in the EU without having to go through the exemption process, they need to thoroughly evaluate their complete supply chains. Electrolytic gold plating is just one example application where a suitable alternative to standard commercial products exists, allowing manufacturers to meet REACH requirements while maintaining the quality and reliability their customers expect.