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.
|Published (Last):||1 August 2005|
|PDF File Size:||14.88 Mb|
|ePub File Size:||14.88 Mb|
|Price:||Free* [*Free Regsitration Required]|
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 gwia. 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.
Martin Wickham reviewed previous findings and gave an update on current work. But, because of RoHS legislation, increasing numbers of components were only available with pure tin finishes. Plated brass, 0050 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 geix these substrates during the 32 years of the study.
Using a tin plating process deliberately chosen for it high propensity to whiskering, NPL had developed a parallel plate test vehicle that had been enabled electrical detection of failure. 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.
Charles Cawthorne then introduced Dr Mark Ashworth of Loughborough University, who discussed the effect of plating methodologies, the first of two presentations describing research carried out at Loughborough into mechanisms and strategies for tin whisker mitigation. Whisker growth was reduced by increasing deposit thickness and by deposition at higher current densities.
geia std 2 pdf – P(1) –
Other resources include work performed in to benchmark the Pb-free technical knowledge base as well as develop a roadmap and plan to close those technical data gaps [13, 14]. Please first log in with a verified email before subscribing to alerts. A distinguished group 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.
Therefore, the use of adequate reflow soldering processes is critical for producing solder joints that are acceptable for their end-product use environment. While the Pb-free movement may appear ominous and challenging, there are tools and resources available to the designer. Environment Impact on Assembly, Printing and Reflow.
A Circuitnet Media Publication. The name was chosen around by a group of engineers from aerospace, defense, and harsh environment ADHE organizations. This Standard establishes processes for documenting the mitigating steps taken to reduce the harmful effects of tin finishes in electronic systems. Strategies were now based on protective barriers, re-finishing of component terminations, and automatic coverage of pure tin finished surfaces by tin-lead solder during the assembly process.
Need more than one copy? Finishes to ub avoided were silver, plated geua, any tin plating over brass without a copper 005 nickel barrier, and bright tin.
In a recent SMT survey, we asked the following question: 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.
This standard is also available to be included in Standards Subscriptions. We have no amendments or corrections for this standard.
A whisker one micron in diameter could support a current of 10 mA. 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. Consequently, manufacturers of high-reliability electronics with RoHS exemption were left with no alternative but gsia manage tin-lead obsolescence by avoidance or mitigation.
Tin Whisker Mitigation Methodologies: Report from SMART Group, Part 1
A proprietary bright tin plating process was used. The assemblies were constantly monitored at a test voltage of 15 volts with a series resistor to limit current to 15 milliamps. 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.
This standard is not included in any packages. 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.
While considerable progress has been made in closing Pb-free knowledge gaps, the challenge of characterizing performance and reliability still needs to be addressed. 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.
And he quoted instances of systems failure in communications satellites originating from tin whiskers. If the document is revised or amended, you will be notified by email.
Other viable mitigation practices were hot-dip tinning for structural steel parts, or hot-oil fused tin plating. This standard is applicable to Aerospace and High Performance electronic applications which procure equipment that may contain Pb-free tin finishes.
He showed several examples of actual failures, and other instances where whiskers had grown but not yet been detected electrically. This paper presents a summary of efforts from document inception to document release. Although equipment designed to go into h was exempt from the RoHS Directive, the reliability of space projects clearly depended on the integrity of PCBs, components and assembly processes.
You can download gb open this file to your own computer but DRM prevents opening this file on another computer, including a networked server.
Living With PB-Free in High Performance Engineering Design
gdia Each batch of eight boards was delivered to consortium bh for coating and returned to NPL for testing. You may delete a document from your Alert Profile at any time.
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. In summary, as the standards had evolved, they had become increasingly definitive with regard to component-to-component spacing design rules.
The body configuration of SMT electrolytic capacitors results in the solder joints being only partially visible for optical inspection purposes.
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.