Why are component manufacturers switching to lead-free components?

The European Union has passed a law that took effect on July 1, 2006, which bans lead and other hazardous substances from electronic products manufactured or sold in Europe. This is also a serious issue in Japan (not all of Asia), however they do not have any pending laws. The U.S. does not have any pending legislation in this area but the desire to service customers in these regions will drive all suppliers worldwide to a lead-free offering. The reasons for this initiative are strictly environmental.

How are our component suppliers handling this change?

There are several different courses of action that suppliers have chosen to take. These actions are listed on a supplier-by-supplier basis in our Supplier Part Number Identification summary created by Avnet. In general, our suppliers are either converting all devices to lead-free, choosing to carry both types of each part, or electing not to manufacture lead-free devices at this time.

How will this affect our OEM customers?

A change from a traditional device to a lead-free device may require a customer change in soldering process temperature. However, it is possible that the process does not need to be changed. Each case needs to be tested and qualified by the customer's engineering team. Lead-free components may also have different moisture sensitivity levels (MSL), which may cause process changes. The information regarding these possible changes is provided by the supplier in its product change notification or in the data sheet. Some suppliers will be changing to lead-free parts without changing their nomenclature and these suppliers can be identified in the Supplier Part Number Identification summary.

Will the change to lead-free components affect the cost of these parts?

The cost of lead-free parts needs to be determined on an individual supplier basis; some of this information is located in the Suppler Part Number Identification summary. In general, lead-free parts will cost the same as the traditional parts. However, there are exceptions to this trend based on supplier and on individual devices.

Are there any quality drawbacks to lead-free components?

Extensive research being conducted on the formation of tin whiskers in lead-free solder joints which can cause electrical shorts. This is a smaller issue in commercial applications; however, it becomes more significant in defense or aerospace applications. There is a possibility that the Tin (Sn) substance, when pure Tin (matte Sn) is used, begins to branch out. This branch could break off, especially in a high-stress fast-paced environment, and create electrical problems.

Is there a universal part number change that will be made to lead-free devices?

No, each supplier will choose its own method of denoting a lead-free device. There are a few suppliers who are not changing their nomenclature, and they can be identified in the Supplier Part Number Identification summary.

What are the contract manufacturers (CMs) doing about lead-free components?

The major contract manufacturers are prepared to solder using traditional components, lead-free components, or a board containing a mix of both types of components. The remaining CMs will need to be contacted individually to identify their lead-free capabilities.

Are the lead-free devices the same form, fit, and function?

Most lead-free packages are form, fit and function into a traditional SnPb solder process. There are exceptions.For example a lead-free ball grid array (BGA) package requires a temperature increase to a minimum of 225^c, from the 205-220^c range used in traditional SnPb solder, in order to achieve proper solderability. Furthermore, this process is not reverse compatible. A traditional SnPb device is not form, fit and function with a lead-free solder process. The reliability of the solder joints is poor and the traditional SnPb component must be qualified to handle 260^c, which most are not.

How are the devices physically changing?

The traditional material used for soldering and for lead (pin) finishing on devices is SnPb. The most widely accepted alloy used for lead-free soldering is SnAgCu. Most suppliers will be using pure Tin (matte Sn) as their lead finishing of lead frame packages and SnAgCu for the solder sphere of array packages (BGA). There are several other options that various suppliers may be using for lead (pin) finishing, such as: Tin Bismuth (SnBi), Nickel Palladium Gold (NiPdAu), Tin Silver Copper (SnAgCu), Tin Copper (SnCu), Tin Zinc (SnZn), and others.

Are there special concerns for defense and aerospace applications?

Yes, the possibility of tin whiskers, from the use of pure tin (matte Sn) as a lead (pin) finish, is a major concern for defense and aerospace manufacturers. Most defense or aerospace customers will not use components with a pure tin lead plating finish. Other solutions need to be provided for this market segment. Lead-free array packages (BGA) are made of SnAgCu and will be accepted by defense or aerospace customers.