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We have no amendments or corrections for this standard. 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.
Using the analogue of two sword-fencers for illustration, Wickham explained different failure modes: Dr Ashworth stressed that these observations related to the particular proprietary electroplating chemistry used in the study, and that other commercial formulations might demonstrate different relationships between current density, deposit microstructure and whisker growth.
Finally, a good number of texts and a continuously increasing amount of data is now available in the open literature.
Living With PB-Free in High Performance Engineering Design
Trends for Geiq Ultra Miniature Chips. 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.
Since the introduction of the RoHS legislation inthe threat of tin-whisker-related short circuit failure from pure tin finished components has remained a major concern within the high-reliability electronics manufacturing industry.
Proceed to Checkout Continue Shopping. The focus is to provide insight and information such that the design geka maintain performance requirements for aerospace, defense, and high-performance ADHP products and systems.
There had been a move away from component termination material type, structure and processing as specific mitigation strategies. A Circuitnet Media Publication. Nine batches had been built to date, together with control assemblies with no coating, all of which had shown extensive whiskering before any evidence was seen on the coated examples.
Level 3 managed whisker risks through complete avoidance. But how do we set about mitigating against such failure where the use of pure tin finished components is unavoidable?
Having started out as a “laundry list” of Pb-free concerns and challenges identified by the ADHP industry, the guide is structured such that those “delta” considerations, i. Subscription pricing is determined by: The plan included a list of tasks necessary to provide ADHP engineers sufficient information to minimize gfia associated with Pb-free solders and finishes.
It was intended to continue ageing the test vehicles and review failures after a further six months, and to visually inspect the assemblies again after twelve months, also to build control assemblies to investigate the effect of temperature during coating. He showed several examples of actual failures, and other instances where whiskers had grown but not yet been ub electrically.
He began his presentation on problems associated with whisker growths with egia remarkable time-lapse video recorded by researchers at Brown University, showing the initiation and growth of a tin whisker geiq a steady rate of about 1 micron per hour over a period of 40 hours. Other resources include work performed in to benchmark hbb Pb-free technical knowledge base as well as develop a roadmap and plan to close those technical data yb [13, 14].
Although higher currents would cause instant burn-out, in high-vacuum conditions a short circuit could result in a plasma discharge. Remoteness and the inability to repair systems in situ obviously made the reliability issue even more critical, albeit for example Voyager 1 was still functioning after 39 years in operation. Using a tin plating geeia deliberately chosen for it high propensity to whiskering, NPL had developed a parallel plate test vehicle that had been enabled electrical detection of failure.
Some key resources include the following set of standards and handbooks developed for working with Pb-free materials in various electronics applications: Engineers will need to “act like engineers” in order to comprehend this information and apply it to jb needs. As Pb-free technology increasingly becomes the standard for electronic interconnects and finishes, engineers must cope with the various challenges posed by this material.
Charles Cawthorne then introduced Dr Mark Ashworth of Loughborough University, who discussed the hn of plating methodologies, the first of two presentations describing research carried out at Loughborough into mechanisms and strategies for tin whisker mitigation.
Plated brass, tin-plated h with a copper barrier layer, tin plated steel, geix 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.
The deposit characteristics studied were thickness, grain size, morphology, orientation, intermetallic formation and elemental diffusion effects, under varying conditions of temperature, humidity, thermal cycling and applied external stress.
While the Pb-free movement may appear ominous and challenging, there are tools and resources available to the designer. Your Alert Profile lists the documents that will be monitored. This standard is not included in any packages. This standard is also available to be included geua Standards Subscriptions. Other viable mitigation practices were hot-dip tinning for structural steel parts, or hot-oil fused tin plating.
geia std 2 pdf – P(1) –
Need more than one copy? Martin Wickham reviewed previous findings and gave an update on current work. The assemblies were constantly monitored at a test voltage of 15 volts with a series resistor to limit current to 15 milliamps.
This standard is applicable to Aerospace and High Performance electronic applications which procure equipment that may contain Pb-free tin finishes.
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, bb 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.
You may delete a document from your Alert Profile at any time. Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards. On behalf of ESA, a working group led by Dr Dunn had produced a comprehensive set of guidelines for creating a lead-free gia plan, which described 000 problems, requirements and methods relevant 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 find its way into the manufacturing chain.
A whisker one micron in diameter could support a current gea 10 mA. He distributed copies to delegates, and it is available on-line for free download by clicking here. Please first verify your email before subscribing to alerts. The space environment presented particular challenges to electronic systems: Environment Impact on Assembly, Printing and Reflow. Possible future work would investigate the effects of vibration and forced air cooling.
Tin Whisker Mitigation Methodologies: Report from SMART Group, Part 1
Tin Whisker Mitigation Methodologies: Although equipment designed to go into space was exempt from the RoHS Directive, the reliability of space projects clearly depended on the integrity of PCBs, components and assembly processes. 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.
Each batch of eight boards was delivered to consortium partners for coating and returned to NPL for testing.