Lead-free components are a supply chain issue

National Semiconductor supplies Nokia with analog components used in handheld wireless devices and network equipment. Compliance with the European Union’s forthcoming RoHS directive is a topical focus in cooperation between National and Nokia.

Martin Schnepf, EFS and packaging expert from the Quality Assurance Department of National’s European headquarters, says National had already previously eliminated five of the six substances whose use is restricted by the directive, leaving only lead to work upon. The work started back in 2000 and by the end of 2004 lead-free versions were available for over 90 percent of products. Some high-power packages still use lead as a high melting temperature die attaches material. This use is exempted by the RoHS directive.

National has chosen the strategy of continuing to offer its customers leaded and lead-free versions of its products to enable the customers to transition smoothly from the standard production process to the lead-free environment. "We don’t want to put the customer under pressure and say, you have to accept lead-free components as of tomorrow as only those will then be available," Schnepf says.

The lead-free solders have an undesirable environmental side effect: they require a higher reflow temperature than lead-containing solders. Some products will have difficulty withstanding the thermal strain at the strictest moisture sensitivity level.

"More moisture sensitive products need dry-pack shipment with its greater environmental impact. Therefore, the aim is to achieve the same moisture sensitivity level as before", Schnepf says.

For National, RoHS compliance is essentially a supplier management issue. The company maintains lists of banned and reportable substances and requires its suppliers to disclose the material content of their products with concentrations of the banned and reportable substances declared. The suppliers need to provide evidence of compliance with the material restrictions.

"We work almost on a daily basis with these lists. In the same way as Nokia, we have moved antimony-based flame retardants to the list of substances to be phased out. National’s products do not contain the RoHS-banned bromine-based flame retardants PBB and PBDE." National shares Nokia’s objective of phasing out all halogenated flame retardants.

According to National’s plans, all National components will be halogen-free by the end of 2005. National started to compile a material content database in 2001. The material content of all the company’s products is accessible over the Internet. Previously, material content information has been supplied to Nokia in spreadsheet form. In the future, this information will be supplied via RosettaNet. Schnepf says RosettaNet brings a significant improvement in replacing the customers’ different forms of declaration.

"Out of one hundred customers you might get ninety different forms. I’m really looking forward to the day when I no longer need to fill the same information separately in the different data sheets."