Photonic Flash Soldering on Flex Foils for Flexible Electronic Systems
conference paper
Ultrathin bare die chips were soldered using a novel soldering technology. Using homogeneous flash light generated by high-power xenon flash lamp the dummy components and the bare die NFC chips were successfully soldered to copper tracks on polyimide (PI) and polyethylene terephthalate (PET) flex foils by using industry standard Sn-Ag-Cu lead free alloys. Due to the selectivity of light absorption, a limited temperature increase was observed in the PET substrates while the chip and copper tracks were rapidly heated to a temperatures above the solder melting temperature. This allowed to successfully soldered components onto the delicate polyethylene foil substrates using lead-free alloys with liquidus temperatures above 200 °C. It was shown that by preheating components above the decomposition temperature of solder paste flux with a set of short low intensity pulses the processing window could be significantly extended compared to the process with direct illumination of chips with high intensity flash pulse. Furthermore, it was demonstrated that with localized tuning of pulse intensity components having different heat capacity could be simultaneously soldered using a single flash pulse.
TNO Identifier
865863
ISSN
05695503
ISBN
978-150901203-9
Publisher
IEEE
Article nr.
7545417
Source title
66th IEEE Electronic Components and Technology Conference, ECTC 2016; The Cosmopolitan of Las VegasLas Vegas; United States; 31 May 2016 through 3 June 2016
Pages
95-100
Files
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