SMT007 Magazine


Issue link:

Contents of this Issue


Page 104 of 147

SEPTEMBER 2020 I SMT007 MAGAZINE 105 done after 6X pre-conditioning at 245°C before thermal cycling for 250 cycles at 190°C for micro- vias. The resulting failure mode was confirmed as the interfacial separation between the electro- less copper and the target pad copper foil. DOE #1 DOE #1 focused on specific process variables associated with: • Post laser ablation micro-etch pre-treatment (single pass-double pass) • Hold times between laser ablation and loading into the electroless line (level 1: zero hold time; level 2: two-hour hold time) • Electroless copper thickness (0.8–1.0 microns) • The influence of coupon position within the test panel • 36 coupons were related for reliability testing. Using a series of case-history examples, illustrated by a combination of optical micros- copy and X-ray with scanning electron micros- copy and energy-dispersive for failure analysis, showed all failure was electroless lifting. Table 2: Test results for panels and the number of cycles completed before 10% resistance change; all failure was electroless lifting. Table 3: Coupons with unstable results and those failing below 5 IST cycles. All failure was electroless lifting.

Articles in this issue

Archives of this issue

view archives of SMT007 Magazine - SMT007-Sept2020