Package Reliability Performance Study of QFN Device on Different Die Attach Machines

The paper is focused on the reliability performance of quad-flat no-leads (QFN) package evaluated on different die attach machine platforms. Reliability tests were done to check the difference in the quality and reliability performance of the device that undergone die attach process on two different machines. Thermal cycling resulted in significant difference on the two machines, with the device processed in Machine 1 showing reliability failures while on Machine 2 it passed the 1000 thermal cycle. For future works, Machine 2 could be used for devices with critical package reliability requirement.

Ultra-low Residue Flux Applications in RF Front-End Packages

With the leap into the 5G era, the demand for improvements in the performance of mobile phones is on the rise. This is also true for the quantity of radio frequency (RF) front-end integrated circuits (ICs), especially for RF switches and low noise amplifiers (LNA). It is well-known that improvements in performance depend on the combination of new design, package technology, and choice of materials. Ultra-low residue (ULR) flux is an innovative, truly no-clean, flip-chip bonding material. By using ULR flux, the typical water-wash cleaning process can be removed and, in some instances, package reliability can be improved as well. This simplified assembly process will help to reduce total packaging costs. This paper will discuss the application of ULR fluxes on land grid arrays (LGAs) and quad-flat no-leads/dual-flat no-leads (QFN/DFN) packages for RF front-end ICs, as well as the reflow process. The solder joint strength and reliability study will be shared as well.

Die Attach Process Optimization with Enhanced Epoxy Control on Leadframe Package

The paper presents a practical procedure in selecting the best candidate for die attach epoxy control or anti-epoxy bleed-out (anti-EBO) concentration during the introduction of new leadframe configuration. Three different criteria were implemented to measure the relative impact of the anti-EBO into the different interfaces inside a quad-flat no-leads multi-row (QFN-mr) leadframe unit. Die shear test is performed to measure the shear strength and the compatibility of the anti-EBO to the adhesive material. EBO measurement is performed herewith to study the propagation of epoxy bleed-out on the surface of the leadframe with reference to the different level of anti-EBO concentration. Package reliability is employed study the response of different interfaces directly in-contact with anti-EBO through thermal-cycling scenario. Ultimately, understanding the effect of anti-EBO into different set of tests provided a systematic way of selecting appropriate leadframe parameters for QFN-mr leadframe product.

Semiconductor QFN Package with Advanced Interlocking Design

The mechanical interlocking structure for quad-flat no-lead (QFN) assembly for densified leadframe degrades as the package becomes thinner. Detractors such as package reliability and design requirement hinder further qualification of leadframes with increased number of input/output (I/O) pins. In this paper, a new and advanced design of leadframe is discussed and presented with improvement in mechanical interlocking structure of high stress areas such as lead and pad junction. The leadframe is re-designed having lead lines on the lead and pad that will be etched away after molding process replacing full copper base frame. Through application of the design, the effective mechanical interlocking is improved from 60% to 100% for mold-lead and mold-pad interface.

Package Reliability and Integrity Improvements for a Thermally Enhance Non-Conductive Die Attach Adhesive for ASIC Devices on Exposed Pad Packages

Polymers being used in a plastic-encapsulated integrated circuit (IC) package exposed to a humid environment absorbed moisture and expand resulting to a so called delamination failure. Weak or imperfect adhesions between the interfaces of the mold compound and adhesive unto the leadframe surface are often the main sources of these failures. In response to automotive requirements and to ensure excellent package reliability and integrity, delamination in all interfaces should then be eliminated. Thus the primary objective of this work is to fulfill the no delamination criteria in all interfaces after moisture soak for an exposed pad package. To satisfy these requirements, activities includes leadframe design improvements, surface enhancement and bill-of-material changes. With the design improvements implemented, still the material compatibility plays an important role in achieving improved package reliability.