Page 33 - ChipScale_Jul-Aug_2020-Digital

substrate. SST utilizes a free-floating
weight design individually isolated for
each component joint and also uses a
proprietary formula based on the proper
weight for AuSn or other preform alloy
materials for die attach.
X-ray examination results LEADERS IN
The typical X-ray inspection results
are shown in Figure 8. Because of the MICRO DISPENSING
density and thickness of the package
heat sink, to achieve a clear image of TECHNOLOGY
the X-ray, the bottom side of the heat
sink was milled away to make it thinner,
approximately, 100-150µm thick. The SMALL REPEATABLE VOLUMES
average total voiding for all devices was ARE A CHALLENGE, BUT NOT
under one percent, at 0.576% for 10 dies. IMPOSSIBLE IF YOU HAVE BEEN
CREATING THEM AS LONG AS WE HAVE.
Summary
A successful and robust die attach
proce ss is t he key t o long-t e r m
reliability and high performance of a TO DO IT WELL,
microelectronic device. Proper selection WE PROVIDE THREE THINGS:
of materials, their plating, solder alloy
preform and process parameters of the
vacuum reflow process will all have a
direct impact on the overall soldering Dispensing Expertise in a variety of microelectronic
quality (void level). The soldering profile packaging applications.
was developed for die attach of GaN die
with AuSn preform to a AuNi plated Feasibility Testing & Process Verification based
metal ceramic package. The visual on years of product engineering, material flow testing
inspection of the soldered interface and and software control.
the X-ray inspection confirmed proper
reflow temperature and very low void Product Development for patented valves,
levels (under 1%). With properly designed dispensing cartridges, needles, and accessories.
graphite tooling and soldering process
profile, the consistent low-void results can
be achieved in mass production.

References
1. SST Gold Tin Technical Bulletin. Our Micro Dispensing product line is proven and trusted by
2. SST Model 1200 Product Bulletin. manufacturers in semiconductor, electronics assembly, medical
3. SST Plating Requirements Technical device and electro-mechanical assembly the world over.
Bulletin.
4. M. A. Previti, et al., “Four ways to www.dltechnology.com.
reduce voids in BGA/CSP package to
substrate connections,” Global SMT 216 River Street, Haverhill, MA 01832 • P: 978.374.6451 • F: 978.372.4889 • info@dltechnology.com
& Packaging, Aug. 2011 pp: 16-25.

Biographies
Alex Voronel is Director of Global Sales at SST Vacuum Reflow Systems, a Palomar Solution, Carlsbad, CA. He joined SST
International in 2012 as Sales Manager for the Asian region. He now has over 30 years of experience in the microelectronics and
semiconductor industry through his work at Orthodyne Electronic, and Kulicke & Soffa as European Sales Manager. He holds a
BS in Business Administration from the U. of Phoenix. Email avoronel@sstinternational.com
Pierino Zappella is a Process Development Engineer with SST Vacuum Reflow Systems, a Palomar Solution, Carlsbad, CA.
He has written 16 articles and holds seven patents. He has a wide range of experience with semiconductor packaging including
flip-chip infrared sensors, wafer fab sensors, pressure sensors, medical sensors and adhesives. Over his career he has worked for
Ford Aerospace, Aerojet Electro-Systems, Rockwell International/Boeing, Ablestik/Henkel and SST Vacuum Reflow Systems.
He holds a BSEE from the U. of Southern California.

31
Chip Scale Review July • August • 2020 [ChipScaleReview.com] 31