Dealing With Tough Whiskers
Tin-based solders without lead (Pb) are commonly proposed as lead-free alternatives to tin-lead (PbSn). However, pure tin electrodeposits may grow "whiskers" - tiny metal filaments emanating from the surface finish - with the potential to short circuit or break off and interfere with other devices in certain applications. Currently, there are no widely accepted test conditions for determining the predilection of a specific plating finish or plating process to grow whiskers.
The NEMI project tested eight-lead small outline integrated circuit (SOICs) packages with varying thicknesses and different tin-based finishes. These samples were subjected to different environment combinations. Based on the results, the NEMI group has recommended three test conditions: temperature cycling (-55C to + 85C, approximately 3 cycles/hour), temperature humidity tests at 60C/93% relative humidity (RH) and ambient storage (air-conditioned facility). All three tests are required and each test must be performed independently.
In addition to the test specification submitted to JEDEC, NEMI is collaborating with JEITA (Japan Electronics & Information Technology Industries Association) and E3 (a European semiconductor consortium) to develop a test protocol to submit to the IEC (International Electrotechnical Commission). The three groups are working to establish unified whisker test methods worldwide, including pass/fail criteria and fields of application.
The mechanism for whisker growth is not known and further testing may provide some correlation to application life (risk) in applications where these current tin-plated products are used. Work is ongoing in a second NEMI project - the Tin Whisker Modeling Project - to develop a better understanding of whisker formation, which may lead to a better test methodology or validate that these are the best tests that can be carried out.
AngelTech Live III: Join us on 12 April 2021!
AngelTech Live III will be broadcast on 12 April 2021, 10am BST, rebroadcast on 14 April (10am CTT) and 16 April (10am PST) and will feature online versions of the market-leading physical events: CS International and PIC International PLUS a brand new Silicon Semiconductor International Track!
Thanks to the great diversity of the semiconductor industry, we are always chasing new markets and developing a range of exciting technologies.
2021 is no different. Over the last few months interest in deep-UV LEDs has rocketed, due to its capability to disinfect and sanitise areas and combat Covid-19. We shall consider a roadmap for this device, along with technologies for boosting its output.
We shall also look at microLEDs, a display with many wonderful attributes, identifying processes for handling the mass transfer of tiny emitters that hold the key to commercialisation of this technology.
We shall also discuss electrification of transportation, underpinned by wide bandgap power electronics and supported by blue lasers that are ideal for processing copper.
Additional areas we will cover include the development of GaN ICs, to improve the reach of power electronics; the great strides that have been made with gallium oxide; and a look at new materials, such as cubic GaN and AlScN.
Having attracted 1500 delegates over the last 2 online summits, the 3rd event promises to be even bigger and better – with 3 interactive sessions over 1 day and will once again prove to be a key event across the semiconductor and photonic integrated circuits calendar.
So make sure you sign up today and discover the latest cutting edge developments across the compound semiconductor and integrated photonics value chain.
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