Buy GEIA HB (R) Technical Guidelines For Aerospace And High Performance Electronic Systems Containing Lead-Free Solder And Finishes. Find the most up-to-date version of GEIA-STD at Engineering TechAmerica GEIA-HB Technical Guidelines for Aerospace and High Performance Electronic Systems Containing Lead-Free Solder.
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Finally, a good number of texts and a continuously increasing amount of data is now available in the open literature. This paper presents a summary of efforts from document inception to document release. With Professor Geoff Wilcox taking over as moderator, Charles Cawthorne began his own presentation by remarking that, since first observed inand despite many years of study, the mechanism of tin whiskering was still not fully understood and predictive modelling was not yet possible.
A whisker gea micron in diameter could support a current of 10 mA. Please first log in with a verified email before subscribing to alerts. Nine batches had been built to date, geiq with control assemblies with no coating, all of which had shown extensive whiskering before any evidence was seen on the coated examples.
It was intended to continue ageing the test vehicles and review failures after a further six months, and to visually inspect the assemblies teia after twelve months, also to build control assemblies to investigate the effect of temperature during coating. He went on to discuss the detail requirements of Levels 2B, 2C and 3, with particular reference to the use of conformal coatings to form a physical barrier. While considerable progress has been made in closing Pb-free knowledge gaps, the challenge of characterizing performance and reliability still needs to be addressed.
A series of collaborative projects had been carried out at the National Physical Laboratory to evaluate conformal coating as a tin whisker mitigation strategy for printed circuit assemblies. Consequently, manufacturers of high-reliability electronics with Gria exemption were left with no alternative but to manage tin-lead obsolescence by avoidance hg mitigation. A distinguished geka of experts gathered at Loughborough University in the East Midlands of the UK to share their knowledge with a room-full of engineers from the defence, aerospace and high-reliability electronics sector, at a seminar organised by SMART Group.
Tin Whisker Mitigation Methodologies: Report from SMART Group, Part 1
The defining standard for tin whisker susceptibility of tin and tin alloy surface finishes was JEDEC JESDA, an accelerated test used by component manufacturers, but there was some doubt as to the reliability of results since tin whiskering was such an unpredictable phenomenon. He distributed copies to delegates, and it ggeia available on-line for free download gea clicking here.
But how do we set about mitigating against such failure where the use of pure tin finished components is unavoidable?
Some key resources include the following set of standards and handbooks developed for working with Pb-free materials in various electronics applications: Dr Dunn had collected data on whiskering effects over a period of 32 years, using the C-Ring test to introduce tensile and compressive stress, with different metal substrates, barrier layers and tin plating thicknesses, and the results were shortly to be published.
And he quoted instances of systems failure in communications satellites originating from tin whiskers. As the voice of the U. Therefore, the use of adequate reflow soldering processes is critical for producing solder joints that are acceptable for their end-product use environment. Using the analogue of two sword-fencers for illustration, Wickham explained different failure modes: Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards.
A remarkable observation was that in some instances it could be several years before whiskers began to grow, depending on the substrate and stress level.
Geai 3 managed whisker risks through complete avoidance. The assemblies were constantly monitored at a test voltage of 15 volts with a series resistor to limit current to 15 milliamps.
geia std 2 pdf – P(1) –
The body configuration of SMT electrolytic capacitors results in the solder joints being only partially visible for optical inspection purposes. Environment Impact on Assembly, Gela and Reflow. Level 3, which was relevant to equipment designed to be sent into space, gsia the use of pure tin finishes.
Plated brass, tin-plated brass with a copper barrier layer, tin plated steel, tin-plated steel with a copper barrier layer, all displayed their own characteristics, sometimes predictable, sometimes not, but fused tin plating showed no whisker nucleation on any of these substrates during the 32 years of the study.
With a heavy dependence on COTS to maintain a competitive edge, the industry is heavily influenced by the commercial supply chain and its increasing use of Pb-free materials.
The name was chosen around by a group of engineers from aerospace, defense, and harsh environment ADHE organizations. We have no amendments or corrections for this standard. A Circuitnet Media Publication. The space environment presented particular challenges to electronic systems: But, because of RoHS legislation, increasing numbers of components were only available with pure tin finishes.
On behalf of ESA, a working group led by Dr Dunn had produced a comprehensive set of guidelines for creating gia lead-free control plan, which described the problems, requirements and methods hg to the preparation of a plan for companies to control against the use of lead-free components and to ensure that pure tin did not 22 its way into the manufacturing chain.
Pulse plating could be used as a means of manipulating the grain structure and orientation of the tin deposit, and in some instances showed reduced whisker growth compared with direct current deposits. In a recent SMT survey, we asked the following question: Standards Subsctiption may be the perfect solution. Remoteness and the inability to repair systems geix situ obviously made the reliability issue even more critical, albeit for example Voyager 1 was still functioning after 39 years in operation.
Trends for Printing Ultra Miniature Chips. The focus is to provide insight and information such geiaa the design will maintain performance requirements for aerospace, defense, and high-performance ADHP products gfia systems. Subscription pricing is determined by: The plan included a list of tasks necessary to provide ADHP engineers sufficient information to minimize risks associated with Pb-free solders and finishes.
Need more than one copy? One observation was that failure predominantly occurred at the edges of plates, where full coating thickness was not maintained around the right angle bend, and this geometry was a characteristic feature of component leads. This standard is also available to be included in Standards Subscriptions. Cawthorne reviewed the definitions of the mitigation control levels defined in GEIA-STD, commenting that the required level would normally be a function of the design authority in consultation with the customer, and that military applications would typically expect mitigation to at least Level 2B—risks managed primarily through mitigations, including design rules, and more likely 2C—risks managed more by avoidance and less by mitigation.