Samples are subjected to three main environmental exposures for a specified period. I also recognize the tin whisker study group leader, dr. The industry needed a test for assessing the susceptibilty of tinbased finishes to tin whisker formation and growth. To assess tin whisker growth and the use of nickel as an underlayer material, the engine control unit. Numerous rohscompliant solders are available today, some of. One comes from the international electronics manufacturing initiative inemi. Thickness of a metal whisker compared to a human hair.
Michael osterman, for his insightful comment and help. Jsb tech pte ltd product flexible flat cable whisker. Evertiq new tin whisker testing and reporting standard. Electrical tin whisker testing national technical systems.
Current methods for tin whisker mitigation strategy which uses gold au plated on a layer of nickel with the based copper cu conductor wire terminals of flexible flat cable ffc is effective, but becoming uneconomical as gold price has increased over four folds over the past 10 years. Many obstacles have had to be overcome on the path to compliance, not the least of which was an entire new line of processing equipment and processes reflow, assembly, rework, materials development, etc. Tin whisker acceptance test requirements inemi tin whisker. The international electronics manufacturing initiative inemi a collection of electronics manufacturers that produce highreliability products has developed a list or recommendations for testing and mitigation. Tin whisker controlled flexible flat cable digipas. A tin whisker is a spontaneous columnar or cylindrical filament, which can branch, of monocrystalline tin emanating from the surface of a plating.
Current methods for tin whisker mitigation strategy which uses gold au plated on a layer of nickel with the based copper cu conductor wire terminals of flexible flat cable ffc is effective, but becoming uneconomical as gold price has increased over four folds over past decade. Set of recommendations to help reduce risk of tin whiskers. Reliability products updated may 2005, inemi tin whisker user group. Rohs compliance in safety and reliability critical. Executive summary the inemi tin whisker user group consists of eleven large manufacturers of highreliability electronic assemblies. During the exposure time, laboratory personnel periodically inspect the samples for any tin whisker growth. Tin whiskers testing using conformal coatings as a mitigation.
Images are the examples of tin whiskers observed in calce experiments. A large area of concern with the use of tinplated or pure tin component finishes is the occurrence of tin whiskers. Tin whisker risk mitigation for highreliability systems integrators and designers integrators and designers of highreliability systems exert little or no control over componentlevel plating processes that affect the propensity for tin whiskering. Pdf standards for tin whisker test methods on leadfree. These commercial size 0805 ceramic chip capacitors have pure tin plated terminations over a nickel barrier layer. The inemi tin whisker user group consists of eleven large manufacturers of highreliability electronic assemblies. Nts is fully equipped to perform tin whisker testing per jedec, inemi. Introduction in spite of more than five decades of research done on tin sn whisker growth see reference 3. Matte tin over copper whisker growth data built into software.
Tin whiskers are real and complex maxim integrated. The organizations tin whisker user group, made up of 11 manufacturers of electronic assemblies. After many studies and analysis the tin whisker group of inemi recommended three tests to evaluate the whisker growth propensity of plating finishes. Accelerated tin whisker test team tin whisker modeling team tin whisker user group. Electrical tin whisker testing national technical systems nts. At this time, there is no method known to guarantee the elimination of tin whiskers over the life of a product. Soldertec uk government dti project development of a standard test method for tin whisker measurement, march 2002 july 2004. Because there is no acceleration factor, the user group felt that saturation was necessary. Such assessments are a required element of tin control plans compliance with geiastd00052, level 2. The phenomenon was first identified within terrestrial electronics, but these whiskers are known to grow rapidly out of pure tin in the weightlessness, vacuum and temperature extremes of space. These whiskers, which can grow on the tin leads and terminals used to attach chips and components to circuit boards, have been implicated in past failures on orbit.
However, inemi user group members have accepted that meeting these requirements will reduce the density and length of tinwhiskers. The inemi tin whisker user group consists of eight large manufacturers of highreliability electronic assemblies. In the paper results of investigation of whisker formation on the pwb immersion tin coatings as well as on the electroplated sn on leads and terminations of. About tin whiskers are electrically conductive, crystalline structures of tin that sometimes grow from surfaces where tin especially electroplated tin is used as a final finish. In situ tensile testing of tin sn whiskers in a focused.
Tin whisker risk assessments used to be performed by a small group of smes, are now being performed by thousands of engineers across the entire industry. Edn inemi releases tests to id tin whisker problems. However, due to the rohs directives ban on the use of lead in solder, most. Tin whisker mitigation tin whisker mitigation coatings. Project webinars these webinars are for inemi members only unless otherwise noted ultra low loss laminatepcb for high reliability and performance endofproject webinar march 78, 2017 connector reliability test recommendations endofproject webinar april 67, 2016 automotive electronic material challenges endofproject webinar. This experiment documents and monitors tin whisker growth on one lot of pure tinplated multilayer ceramic capacitors mlccs mounted. Theories of tin whisker growth as a dislocation mechanism most popular theories have been largely disproved those who have disproved these theories have pointed to recrystallization the only nondisproved theories of tin whisker growth are recrystallization and grain growth based. Tin whiskers is on a mission to make artfully engineered beers, and is the perfect place for beernerds and nonnerds alike. In collaboration with various research institutions, v8 whiskerless ffc was developedd and tested by sgs better than inemi class 1 standard employing tinalloy manufacturing process technology, which is whisker free, costeffective and environmentally friendly compared to. Accepted by most who are knowledgeable in this area. Electronics production december 18, 2006 set of recommendations to help reduce risk of tin whiskers the international electronics manufacturing initiatives tin whisker user group announces a major update of its publication, recommendations on leadfree finishes for components used in highreliability products. These companies, which annually purchase many millions of dollars of components, formed the user group to develop recommendations for leadfree surface finishes for highreliability electronic applications.
Coyle said that even when a company adopts the recommendation standards, tin whiskers may still be a problem. One common approach to mitigating risk is to solder the pure tin. Our mission is to forecast and accelerate improvements in the electronics manufacturing industry for a sustainable future. The scientific community has yet to agree on the reason for tin whisker growth. The discussion covers the problems caused by the removal of lead from electronics, not the least of which is the tinwhisker problem, our subject. Coyle is also cochair of inemis tin whisker user group. Proceedings of ipc printed circuits exposition, apex, and the designers summit. Tin whiskers have been observed to grow to lengths of several millimeters mm and in rare instances to lengths up. An algorithm to assess the applicationspecific risk of. The tin whisker test group of the international electronics manufacturing initiative inemi proposed a set of test that were standardized by jedec solid state technology association once known as the joint electron device.
These test conditions represent a minimum set of conditions that shall be used to assess the propensity for tin whisker growth on any given tin finish under study. In some safety and reliabilitycritical applications, electronic products are subjected to harsh operating conditions for a lifetime ranging over ten years. Contact plasma ruggedized solutions for tin whisker mitigation services. Limitations of hot solder dip for tin whisker mitigation. Our experts can provide a number of solutions to protect your assemblies and components from tin whisker growth and the difficulties this can create. Risks with lead free part i tin sn metal displays the characteristic of growing tin whiskers from pure tin coatings most actively on relatively thin, electrodeposited or immersion tin coatings, usually months or years from the initial deposition of. Smetana, inemi tin whisker workshop, may 2005 updated 2007. This document took us more than three years to do, said joe smetana, who chairs inemis tin whiskers user group. The inemi tin whisker user group, which is a group of electronics manufacturers that produce highreliability products, is focused on concerns related to the growth of. Rohs will lead to tin whiskers tin whiskers can be reduced, but its doubtful they will ever be eliminated once lead is completely removed from solder.
The three pieces include mitigation practices, process controls and verification testing. Tin whisker acceptance test requirements inemi tin. Recommendations on leadfree finishes for components used in high. The industrys preference, with respect to factors such as solderability, ease of manufacture, and compatibility with existing assembly methods, would be to use pure tin plating as. Rohs, wee, pbfree, leadfree, all buzzwords in this era of ultra green sensitivities.
See who you know at inemi, leverage your professional network, and get hired. Videos of melting tin whiskers in a scanning electron microscope m. For many years, the space industry has been seeking reliable methods to predict and mitigate the risk of conductive whiskers forming in electronic components. The inemi tin whisker user group was formed to minimize the risk of failures from tin whiskers. The common and widely accepted understanding is that whisker growth is induced by compressive forces in the tin layers. Tin whisker analysis of an automotive engine control unit. Jedec and ipc release tin whisker acceptance testing. Therefore, more precise experimental techniques are required to evaluate the mechanical properties of whiskers. But the group says the body of information is still not perfect for longlife products, and whiskers will still form under certain conditions. Tin whisker risk mitigation for highreliability systems. Tin whiskers are small and hard to detect and inspect. Battling the growth of tin whiskers quality magazine.
Tin whisker testing is one way to determine the products susceptibility to growing whiskers or if any mitigation strategy is successful. Jedec released standard tin whisker test methods and acceptance criteria. Initial acceptance testing recommendations from the inemi tin whisker user group called for testing to saturation, the point at which whiskers stop growing. For instance, the emerson dvc6215 remote mount sensor has operating requirements from. Fiber optics testing global market access hardware software testing hydraulics. The risk of whisker growth is high where a coppersurface is covered with pure tin. This condition arises when tin begins to grow tiny filaments known as whiskers. Plasma ruggedized solutions has been providing superior tin whisker mitigation services since the earliest days of our company. Assessing the risk posed by tin whiskers calce site map. Theory of whisker growth the fundamental research about whisker growth is still incomplete. In may 2005, the inemi tin whisker user group released a standard that approves the use of microscopes. Rohs rules will hit supply of noncompliant components. Standards for tin whisker test methods on leadfree components.
Tin whiskers are electrically conductive, single crystal eruptions that can grow from surfaces where tin is deposited on a substrate surface fig. The driving force for tin whiskers is compressive stress in the tin films. The long shard rising from the surface is a tin whisker a spontaneous outgrowth representing a clear and present danger to space missions. Typically no bigger than 1 to 5 microns in diameter and as much as several millimeters in length, they are small, but powerful. Tin whisker acceptance test requirements inemi tin whisker user group, july 28, 2004 1. Challenges of how to assure longterm reliability, while continuing to. The european unions restriction of certain hazardous substances rohs initiative to reduce the use of lead pb is driving the electronics industry to consider alternatives to tinlead alloys in component plating. The trusted news source for powerconscious design engineers. Also, as more knowledge is gained, this document will be revised to.