A reliable wire bond connection for integrated circuit devices is an important gauge in assuring a high-quality product. In comparison to pure copper wires, which are used for low-cost assembly but have oxidation problems, Palladium Coated Copper (PCC) bond wires were used to increase wire robustness, provide an advantage in applications at high temperatures, and meet criteria for good loop stiffness and hardness. However, decapsulated samples have been rejected by reliability engineering, and rework has been needed because wire discoloration was mistakenly identified as oxidized bond wires creating delays in producing the Failure Analysis (FA) result as well as wasting unnecessary resources in the process. The wrong callout happens 47.8% of the time. Through the investigation of chemical compositions, the topography of materials, and the evaluation of bond strength distribution, with some use of statistical analysis tools, this study explains how the issue was resolved. As a consequence, the wrong callout was effectively eliminated.

This study presents a revolutionary methodology in an otherwise tedious and inconsistent manual decapsulation process of copper-wired small outline integrated circuit (SOIC) plastic package. The author explains how the consistency was achieved by adopting important changes such as (1) application of the 1-volt electrochemical bias, (2) optimization of etching solution agitation at 3.5 RPM, and (3) adoption of a symmetrical stainless-steel cathode. With the power of consistency, the added benefit of the adoption changes is the correct measurement of wire bond integrity tests such as wire pull, wire diameter, and magnitude of etch. The paper also discusses additional improvements to address the issue of long cycle time via laser ablation.