Micro bump arrays are used for logic LSIs. Probes for micro bump arrays require good contact, long lifetimes, and low pad damage. Crown-shaped contact probes satisfy these requirements but the fabrication is very difficult. We designed a selective electrodeposition of metal alloys process for the fabrication of the probes and the simulation results showed satisfactory characteristics.
Probe figures are realized using a high-resolution 3D printing technique with 2-photon excitation followed by coating with metal layers. We recognized that high-resolution 3D printing is useful for rapid prototyping of a new probe and is a powerful tool for developing the next generation of polymer probes.
We evaluated the effects of temperature on the acceleration of performance in an electrochemical migration (ECM) reliability test of an FR-4 type printed wiring board (PWB). We evaluated the accelerated test conditions from 30°C to 140°C. Our test showed that the ECM failure mode at 30°C was different from the ECM failure mode at 85°C to 140°C.
The actual failure time of the test result at 30°C was shorter than the failure time extrapolated to the failure time from 85°C to 140°C. This is because the temperature does not accelerate at temperatures between 30°C and 140°C, so it did not conform to the Arrhenius equation.
In this study, we demonstrated the fabrication of conductive patterns on organic film using a photo-sintering process with copper nano-ink. The resistivity of the photo-sintered copper film was 4 μΩ･cm, which was twice as much as bulk copper. The peel strength of electrodeposited copper on the photo-sintered copper film reached 10 N･cm-1, which was good adhesion to polyimide. The copper metal mesh on hard coat polyethylene terephthalate fabricated using gravure offset printing and photo-sintering of the printed copper nano-ink showed more than 25 pF of electrical capacitance and behaved as a touch sensor on a touch panel module.