September, 2019
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Page 81 Reducing Voiding Under Thermally Challenged Devices Continued from page 79
Drivers of Low-Voiding Standards The range of component sizes and types, as
well as the PCB component density, is expanding considerably. According to market analyst Prismark, the convergence of ball pitch decreases, package size increases, and SiP/wafer-level pack- age integration is underscoring the impact of localized heat — especially when real estate is being compromised. With increased component functionality and
density, greater heat generation is natural. The suspicion is that voiding will entrap the heat, pre- vent inadequate dissipation and create hot spots, which could potentially cause component fragility rather than the traditional failure mechanism of solder joint fatigue. Specifically, in the automotive
sector, large, 0.3 x 0.3 to 0.4 x 0.4 in. (7 x 7 to 10 x 10 mm), QFNs are being used in infotainment systems. Smart devices and memory chips now con- tain pitches as small as 0.008 in. (0.2 mm), with 0.012 in. (0.3 mm) becom- ing more prevalent. Both SiPs and wafer-level packaging integration are driving PCB real estate density, mak- ing more of the board a live conduit. All of these converging factors
and their subsequent effect on heat generation are raising voiding con- cerns among electronics assemblers.
Next-Gen Solder Materials The ultimate objective is to for-
mulate a flux that spans the range of component requirements offers capa- bility for maximum reliability, deliv- ers logistics and process stability, and lowers the cost of ownership. In short, manufacturers want a low- voiding, high-reliability, high-capa- bility, and sustainable solder materi- al that is competitive in their respec- tive markets. Leveraging the proven perform-
ance of an award-winning, tempera- ture-stable flux platform, a new sol- der material has been developed to meet the challenging requirements of emerging voiding guidelines imposed by top-tier EMS companies. Henkel’s LOCTITE® GC 18
achieves low voiding incidents across a diverse component range, including 008004 (0201 metric) chip resistors 0.02 in. (0.4 mm) pitch BGAs, SOICs, QFPs, and QFNs greater than 0.4 x 0.4 in. (10 x 10 mm). Validated with various surface finishes, board sizes, components, atmospheres, reflow profiles, and ovens, the material’s voiding performance is exceptional. Notably, the low voiding results observed with the temperature-stable material were achieved with reflow in air. The material still provided excep- tional wetting and coalescence per- formance in long, hot profiles for 008004 (0201 metric) and 0.02 in. (0.4 mm) pitch components — a capability that allows assembly specialists to further reduce operational expendi- tures and lower nitrogen use. Other air reflow performance
attributes include high humidity resistance, minimal hot slump at 374°F (190°C) and excellent solder joint appearance when compared with other lead-free solder joints. Consistent with the LOCTITE
GC platform performance character- istics, LOCTITE GC 18 is stable for one year when stored at 79.7°F (26.5°C) and for one month at tem- peratures up to 104°F (40°C). The enduring material consistency pro- vides benefits across the value chain,
from transport to onsite warehousing and produc- tion, allowing resource optimization, excellent in- process performance and the ability to source a single material for a wide spectrum of product builds.
up to four hours of abandon time, LOCTITE GC 18 is formulated for excellent transfer efficiency and is compatible with challenging surface finishes, such as OSP- and/or Ni- or Zn-coated copper and HASL. While the voiding debate rages on, the
With high Cpk during continuous printing and
good news is that there is a solution that delivers high reliability across the compo- nent spectrum, regardless of the ultimate findings. Contact: Henkel Corp., 14000 Jamboree
Voiding may trap heat inside components,
preventing inadequate dissipation and leading to component fragility.
Road, Irvine, CA 92606 % 714-368-8025 E-mail:
juan.serrano@
henkel.com Web:
www.henkel.com r
See at The Battery Show, Booth 1201
See at SMTAI, Booth 632
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