Effects of moisture and elevated temperature on reliability of interfacial adhesion in plastic packages

Abstract

The interfacial-adhesion performance between the lead frame and molding compound was studied after temperature cycles and hygrothermal aging, simulating a typical package-assembly process. The hygrothermal aging involved a treatment at 85°C and 85% relative humidity (RH) for 168 h and three cycles of infrared (IR) solder-reflow condition. The interfacial-bond strengths were measured using shear and lead-pull tests. The lead-frame surface finishes studied include a bare Cu, microetched Cu, spot Ag coating, Ni, Pd/Ni, and Au/Ni coatings. Special emphasis was placed on the study of the changes in surface characteristics and the corresponding interfacial adhesion after various manufacturing processes. It was found that moderate thermal cycles enhanced the interfacial adhesion for all coated lead frames, except the Ni coating. Hygrothermal aging was detrimental to the interfacial-bond strength, especially for hydrophilic or polar surfaces, such as bare Cu, Ag, Pd/Ni, and Au/Ni coated lead frames. The introduction of tiny dimples etched on the lead frame was effective in mitigating the reduction in interfacial-bond strength arising from hygrothermal aging. This result confirms the important role of the mechanical-interlocking mechanism provided by dimples in retaining the interfacial adhesion in a humid environment.

Epoxy-organoclay nanocomposites: morphology, moisture absorption behavior and thermo-mechanical properties

“…For instance, moisture diffusion through epoxy is the major cause of corrosion of metallic components in electronic packages. The adhesion of epoxy to a substrate is also adversely affected by moisture absorption [12], the degradation being particularly pronounced at temperatures higher than the glass transition temperature of epoxy [13]. Moisture may also be absorbed by uncured epoxy, thus affecting the cure kinetics of epoxy and the thermomechanical properties of the cured material.…”

Barrier performance of silane–clay nanocomposite coatings on concrete structure

“…The average contact angles were recorded immediately after the droplets touched the substrate and at least 5 measurements were conducted for each test. The theoretical considerations of wetting are based on the Young-Dupre equation [14] that defines the work of adhesion, W a , between the liquid and solid as a function of contact angle θ:…”

Improvement of the Adhesive Strength of the Leadframe and Epoxy Resin by Forming Organic Molecules–Metal Composite Interface

“…It should be noted that there is a concern of interface delamination phenomenon at the interface between LF (internal wiring material) and the epoxy resin (sealing material), because they are adhered by hydrogen bonding which shows weaker bonding strength compared to metallic bonding and covalent bonding, and moreover, the interface adhesive strength significantly drops under the high temperature/high humidity condition upon reflow. Such phenomenon is the main factor of package cracks, which is highly problematic for the reliability of semiconductor package .…”