Experimental location of damage in microelectronic solder joints after a board level reliability evaluation

- A High Frequency Structure Simulator (HFSS) investigation is used to evaluate the effective relative permittivity.
- The fault location on a daisy-chained structure with pattern ground can be analyzed by time-domain reflectometry (TDR).
- The fault location in critical solder balls as predicted by TDR correlate well with observation by cross-section.

Reliability evaluation of integrated circuit (IC) packages to assess drop impact is critical, especially in the case of handheld electronic products. The objective of this study is to experimentally identify the location of damage in solder joints in electronic packaging after a board level reliability (BLR) evaluation. The BLR drop test is a useful way to characterize the drop durability of different soldered assemblies onto a printed circuit board (PCB). It is also of great importance when there is a need to evaluate the solder joint between the chip package and PCB through a daisy-chained structure during the evaluation period. However, there is no detailed information available on a pattern ground with a hatched copper PCB layout for high speed responses that are closely related to actual working conditions. In this paper, a fault location on a daisy-chained structure with a pattern ground is shown through a non-destructive analysis using a time-domain reflectometry (TDR) approach. The results obtained in this project indicate that the TDR approach can be used to detect the location of a crack in the string based on changes in the waveform response. The fault location in critical solder balls as predicted by TDR correlate well with experimental observation by cross-section.

153