Influences of copper roughness on the electrical and mechanical performances of embedded capacitance materials

Abstract

In this letter, the influences of copper roughness on the electrical and mechanical properties of embedded capacitance materials (ECMs) are investigated. The very low-profile ECM (VLP-ECM) is found having a capacitance of 1.24 nF/cm² with the lowest tolerance of 5.5% (1 × 1 mm). In contrast, the rolled anneal ECM has a higher tolerance, and invalid embedded capacitors are even found in the electrodeposited ECM. The VLP-ECM is also found having the highest peel strength of 10.2 N/cm among the three ECM. The appropriate copper roughness (R_z ≤ 3.5 μm) is beneficial for getting a uniform coating for the restriction of the flowing of BaTiO₃/epoxy composite. And the hook functioned copper bulges can increase the contacting area against stripping. Therefore, the ECM fabricated with VLP copper foil has the best electrical and mechanical performances, which is favored in the application of printed circuit boards manufacturing.

Keywords:

• Copper foil
• surfaces
• embedded capacitor
• electrical properties
• peel strength