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Technical Articles From Lockheed Martin Corporation

Read technical articles about electronics manufacturing added by Lockheed Martin Corporation


3 technical articles added by Lockheed Martin Corporation

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Lockheed Martin is a global security and aerospace company that employs about 112,000 people worldwide and is principally engaged in the research, design, development and manufacturing of advanced technology systems.

Bethesda, Maryland, USA

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(3) technical library articles

HALT Testing of Backward Soldered BGAs on a Military Product

Nov 19, 2015 | B. Gumpert, B. Fox, L. Woody

The move to lead free (Pb-free) electronics by the commercial industry has resulted in an increasing number of ball grid array components (BGAs) which are only available with Pb-free solder balls. The reliability of these devices is not well established when assembled using a standard tin-lead (SnPb) solder paste and reflow profile, known as a backward compatible process. Previous studies in processing mixed alloy solder joints have demonstrated the importance of using a reflow temperature high enough to achieve complete mixing of the SnPb solder paste with the Pb-free solder ball. Research has indicated that complete mixing can occur below the melting point of the Pb-free alloy and is dependent on a number of factors including solder ball composition, solder ball to solder paste ratio, and peak reflow times and temperatures. Increasing the lead content in the system enables full mixing of the solder joint with a reduced peak reflow temperature, however, previous research is conflicting regarding the effect that lead percentage has on solder joint reliability in this mixed alloy solder joint....

Tin Whisker Risk Management by Conformal Coating

Oct 22, 2015 | Linda Woody, William Fox; Lockheed Martin Missiles and Fire Control

The objective of this study is to evaluate conformal coatings for mitigation of tin whisker growth. The conformal coatings chosen for the experiment are acrylic, polyurethane and parylene. Also included in this paper are tin whisker inspection results of tin-plated braiding and wire that was exposed to an environment of 50°C with 50% relative humidity for over five years....

Solder Paste Stencil Design for Optimal QFN Yield and Reliability

Jun 11, 2015 | B. Gumpert

The use of bottom terminated components (BTC) has become widespread, specifically the use of Quad Flat No-lead (QFN) packages. The small outline and low height of this package type, improved electrical and thermal performance relative to older packaging technology, and low cost make the QFN/BTC attractive for many applications.

Over the past 15 years, the implementation of the QFN/BTC package has garnered a great amount of attention due to the assembly and inspection process challenges associated with the package. The difference in solder application parameters between the center pad and the perimeter pads complicates stencil design, and must be given special attention to balance the dissimilar requirements...

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