Improvements of the Epoxy–Copper Adhesion for Microelectronic Applications

Abstract

Upcoming electronic devices are required to be further miniaturized. The microelectronics industry and packaging technology focus efforts on optimizing adhesion between plated copper and printed circuit board (PCB) substrate (here epoxy/glass buildup composite), while keeping smooth surfaces for high-frequency application. We propose herein to review and deepen the basic understanding of the sequential buildup process employed worldwide for the past several decades for multilayered PCB manufacturing. This multiscale and interdisciplinary study aims to establish the relationships between degrees of precuring (α), oxidative etching (permanganate desmear wet treatment), and copper adhesion. The epoxy curing states on industrial coupons were evaluated by diffuse-reflectance infrared Fourier transform spectroscopy. Then, atomic force microscopy (AFM) described the desmear performances through topography evolution with α between the different sequence steps. Finally, polymer−copper adhesions were investigated by using peel strength tests, AFM, and X-ray photoemission spectroscopy. We remark that high adhesion strengths were obtained for very smooth surfaces. This study outlines the contribution of the polymer network viscoelasticity (relaxation dynamic) on the polymer−copper adhesion. We observed that faster polymer relaxation rates tended to increase polymer−copper adhesions.

Enhancing peel strength between liquid crystal polymer and copper with plasma treatment, surface oxidation, and silane coating

“…16 Surface oxidation and etching with permanganate is also an effective process to strengthen the bonding force between copper and polymer for FPC manufacturing. 17,18 Adhesive laminate 19 is the most commonly used process in the industry to improve the bonding force between the substrate and copper, but it will lead to an increase in sample thickness. Fully inkjet-printing, 20 laser etching and welding process, 21 and other physical processes 22,23 to activate LCP are all capable of obtaining good bonding performance.…”

“…In addition, different oxidation degrees of copper were explored for bonding properties with resin materials 16 . Surface oxidation and etching with permanganate is also an effective process to strengthen the bonding force between copper and polymer for FPC manufacturing 17,18 . Adhesive laminate 19 is the most commonly used process in the industry to improve the bonding force between the substrate and copper, but it will lead to an increase in sample thickness.…”

Sandwich-Layered Dielectric Film with Intrinsically Excellent Adhesion, Low Dielectric Constant, and Ultralow Dielectric Loss for a High-Frequency Flexible Printed Circuit

“…Nevertheless, it is still a great challenge to balance the paradox between superior dielectric property and excellent adhesion. , As a thermosetting polyolefin resin, 1,2-polybutadiene (1,2-PB) has shown great potential as a matrix resin in the fields of electronics, insulations, adhesives, coatings, automobile tires, , and toughening modifiers . Attributed to the low electronic polarizability of C–C and C–H bonds in polyolefins, 1,2-PB exhibits low dielectric constant and ultralow dielectric loss over wide frequency and temperature ranges. , Unfortunately, unmodified nonvulcanized polybutadiene (PB) also suffers from inherent drawbacks such as poor interfacial adhesive strength between the resin and copper foil and easy creeping, which make it hard to adhere with other substances (e.g., copper foil) and to laminate them.…”

Engineering Copper Adhesion on Poly-Epoxy Surfaces Allows One-Pot Metallization of Polymer Composite Telecommunication Waveguides

“…For example, the microelectronics sector requires thin, smooth, and adherent metallization films for the More than Moore generation, and for this it successfully adapts traditional wet chemistry recipes [7]. Laser structuring was reported to be efficient for the local metallization of line of sight polymer surfaces [8], nature inspired wet chemistry protocols were shown to be efficient for the application of strongly adherent metallic nanoparticles on flexible electronics [9], whereas electroless deposition was shown to be efficient for the metallization of porous polymers [10] and for the roll-to-roll metallization of a wide variety of organic substrates [11].…”