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Technical Briefs
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Volume I, Issue 1


Technical Briefs Home

The President's Corner

Molding Compound Lawsuit Quietly Settled

Lead-Free and the Military / Aerospace Dilemma

GEIA Hot Solder Dip Specification

Ionic Contamination at the Component Level

Column Grid Array: The Solution to BGA Reliability Problems


Lead-Free and the Military / Aerospace Dilemma

Beginning in July 2006, the European Union Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment (commonly referred to as RoHS) will be enforced throughout Europe. RoHS restricts the use of six substances, including lead, which is commonly used in electronics. Manufacturers outside of Europe will have to abide by RoHS if they intend to sell electrical and electronic equipment into Europe.

The RoHS directive has succeeded in driving semiconductor and electronics companies to qualify and adopt lead-free solders. This is a dilemma for military and aerospace. They are being forced to use components and processes that are unproven and, in certain situations, known to be less reliable.  Even though military and aerospace users are exempt from RoHS, the availability of tin-lead finished components is quickly diminishing and is likely to vanish altogether.

In order to meet the RoHS mandate and minimize inventory costs, semiconductor and component manufacturers are converting to lead-free solder alloys worldwide. Almost all components, except Ball Grid Arrays (BGA), are moving to pure-tin finishes. Ball grid arrays are moving to tin-silver-copper (SAC) alloys.

Pure-tin finishes present a huge problem for the military and aerospace community. These finishes are known to be prone to tin-whisker growth. Tin whiskers have caused failures of several weapon and satellite systems, as well as a nuclear reactor shutdown.

The simplest solution to this tin-whisker dilemma is Hot Solder Dip (HSD). It can be used to convert pure-tin finishes to tin-lead or lead-free. Hot solder dipping is a well-established process that has been used in the semiconductor industry for decades.

Figure 1: Tin Whiskers [1]

The military and aerospace industries face another issue as they try to incorporate the lead-free BGAs into a tin-lead environment. Studies have shown that lead-free BGA components are incompatible with tin-lead solders.

The simplest solution to this dilemma is BGA reballing. It can be used to convert lead-free BGAs to tin-lead.

For more information:
Call: 408-956-0100

Six Sigma is actively involved in alloy conversions for military and aerospace customers. Six Sigma, with its history of providing services for the semiconductor industry for over 15 years, has proven to be the leader in the field of hot solder dip, BGA reballing and column attach services. During this time Six Sigma has processed over 20 million components for high-reliability applications.

[1] Galyon, G., J. Smetana and N. Vo (2004). Cause of Tin Whiskers Remains Elusive [Online]. Available at   (accessed July 31, 2005).

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