Improved Electrical Reliability Within EMI-Shielding Case for the Assembly of Advanced Miniaturized Electronic Packages

Mobile applications have become increasingly demanding for the miniaturization of electronic packages over the years. Simultaneously, high electrical reliability of the resulting high-density circuits with electromagnetic interference (EMI) shielding is required to prevent damage and malfunction. We propose a new surface insulation resistance (SIR) test method that utilizes a test coupon enveloped in a brass shield case. Although all pastes passed standard SIR test, our test method offered SIR failure of some pastes due to electrochemical migration (ECM), and additional formulation study helped to find out mechanism of the ECM failure.