Understanding lead frame surface treatment and its impact on package reliability

Lead frame micro-electronic packages are still the most widely used in the semiconductor industry. The surface properties of metal lead frames are involved in several important interfacial interactions within micro-electronic packages and hence have crucial impact on package integrity and reliability. In this work, detailed investigations were carried out to elucidate the chemical compositions of surface treatment solutions as well as the chemical and physical properties of lead frame surfaces. Results from ¹H nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), optical microscopy, and static secondary ion mass spectroscopy (SSIMS) are described. Adhesion testing data obtained from lead frames with different surface treatments, and with die attach adhesives of various chemistries, are reported. In addition, JEDEC reliability tests, using a new die attach adhesive, were performed on molded packages with different packaging material combinations and the results are reported.