A Novel Approach for Temperature-Induced Ball Grid Array Collapse Observation.

Area of Science:

• Materials Science
• Electronics Engineering
• Reliability Engineering

Background:

• Repeated reflow soldering processes can induce solder ball collapse in ball grid array (BGA) packages.
• This collapse is a critical failure mechanism, especially in fine-pitch BGAs, potentially leading to short circuits.
• Existing methods lack in situ measurement capabilities for solder ball behavior during reflow.

Purpose of the Study:

• To develop and validate a novel in situ measurement approach for quantifying BGA solder ball collapse during repeated reflow.
• To investigate the collapse behavior of Sn63Pb37 and SAC305 solder alloys under varying thermal cycling conditions.
• To correlate observed collapse phenomena with potential failure modes like short circuits.

Main Methods:

• A novel in situ measurement technique was developed to monitor BGA solder ball collapse during melting and solidification.
• Ball grid array samples using Sn63Pb37 and SAC305 solders were subjected to thermomechanical analysis (TMA).
• Samples underwent three heating/cooling cycles at 250 °C, 280 °C, and 300 °C, followed by cooling to 100 °C.

Main Results:

• The novel TMA approach successfully captured in situ solder ball collapse behavior for both Sn63Pb37 and SAC305 alloys.
• Distinct differences in collapse characteristics were observed for the two solder types across the tested temperatures.
• The TMA measurements identified instances of short circuits between leads, later confirmed by X-ray analysis.

Conclusions:

• The developed novel approach provides clear insights into solder ball behavior during repeated reflow, aiding in understanding BGA package reliability.
• The findings highlight temperature-dependent collapse variations and the propensity for short circuits in fine-pitch BGAs.
• This in situ measurement technique is valuable for failure analysis and the development of more robust electronic packaging solutions.