Technical Library | 2018-12-05 14:52:23.0
The multilayer ceramic capacitor (MLCC) has become a widely used electronics component both for surface mount and embedded PCB applications. The MLCC technologies have gone through a number of material and process changes such as the shift from precious metal electrode (PME) configurations which were predominantly silver/palladium to base metal electrodes (BME) dominated by nickel. Each of these changes were accompanied by both quality and reliability problems. The MLCC industry is now in the midst of an unprecedented set of challenges similar to the Moore’s Law challenges being faced by the semiconductor industry. While capacitor failures have historically been responsible for a significant percentage of product field failures (most estimates are ~30%) we are seeing disturbing developments in the low voltage (
Technical Library | 2023-08-04 15:27:30.0
A designed experiment evaluated the influence of several variables on appearance and strength of Pb-free solder joints. Components, with leads finished with nickel-palladium-gold (NiPdAu), were used from Texas Instruments (TI) and two other integrated circuit suppliers. Pb-free solder paste used was tin-silver-copper (SnAgCu) alloy. Variables were printed wiring board (PWB) pad size/stencil aperture (the pad finish was consistent; electrolysis Ni/immersion Au), reflow atmosphere, reflow temperature, Pd thickness in the NiPdAu finish, and thermal aging. Height of solder wetting to component lead sides was measured for both ceramic plate and PWB soldering. A third response was solder joint strength; a "lead pull" test determined the maximum force needed to pull the component lead from the PWB. This paper presents a statistical analysis of the designed experiment. Reflow atmosphere and pad size/stencil aperture have the greatest contribution to the height of lead side wetting. Reflow temperature, palladium thickness, and preconditioning had very little impact on side-wetting height. For lead pull, variance in the data was relatively small and the factors tested had little impact.
| 1 |
.gif)
