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Stress isn’t good for anyone, and it certainly isn’t good for SMT/PCBAs, especially when it’s caused by a large Coefficient of Thermal Expansion (CTE) mismatch, says Martin Hart, CEO of TopLine Corporation. That’s why TopLine technical staff will be on hand to discuss solutions for mitigating stress in large heterogeneous modules at the upcoming SMTAI 2019 Conference and Expo in Rosemont, Illinois September 24-25, 2019, in booth #832.
“CTE mismatch results from packaging different materials, with their own CTE properties inside of one package,” Hart says. “This creates tremendous stress when these packages thermally cycle. Materials want to go in different directions at different rates. If the stress can’t be absorbed, the package might fail, and that’s not good for mission-critical parts in Military and Aerospace systems.”
Solutions include using cylindrically-shaped solder columns to absorb CTE mismatch rather than solder balls (as in (Ball Grid Arrays, or BGAs), which have limited ability to withstand environments where there may be wide temperature swings.
“Solder balls have a tendency to crack; whereas solder columns are compliant and can withstand stretching and pulling between modules and the PC board,” Hart says. So TopLine will exhibit CCGA - Column Grid Arrays which are made with non-collapsible high-temperature solder columns for soldering onto PCBs. CCGA packages provide more compliancy than BGA solder balls to absorb stress caused by CTE mismatch.
TopLine manufactures a wide range of Daisy Chain test components, Column Grid Arrays, Particle Impact Vibration Dampers and engineering evaluation kits for process development, experimentation, machine evaluation, solder training, and SMT assembly practice. TopLine products provide hands-on learning for engineers.