New Phosphorus-based Curing Agents for PWB
As a result of the continuous industrial trend towards high density packaging there is a growing demand for highly thermally-stable laminate materials.
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Authored By:
A. Piotrowski, M. Zhang, S. Levchik
ICL-IP, Tarrytown, NY, USA
Y. Zilberman, Eran Gluz
IMI (Tami) Institute for R&D Ltd., Haifa, Israel
Summary
As a result of the continuous industrial trend towards high density packaging there is a growing demand for highly thermally-stable laminate materials. Although the epoxy resin defines the thermal stability, often the flame retardant used becomes the limiting factor in achieving a higher stability. Recognizing this industrial need, the company has developed a new flame-retardant curing agent, Material A.
This is a phosphorus-based polymer which cures epoxy via a very specific mechanism. Common Novolac epoxy resins cured with Material A and a phenol-formaldehyde resin show a Tg >180 Celsius and Td >400 Celsius. In addition to a high thermal stability, Material A also shows a dielectric loss factor lower than commercial phosphorus-based flame retardants.
Conclusions
Material A is a reactive FR specifically designed for high performance laminates. It is a polymeric, phosphorus-based, multifunctional curing agent. The high degree of crosslinking when using Material A results in a high or very high Tg, depending on the formulation. In addition, this material is very thermally stable, even before cure. This, combined with a unique curing mechanism, results in highly thermally-stable laminates even when using simple epoxy Novolacs, with the onset of decomposition above 400 Celsius.
Material A is suitable for high temperature applications. It enables the achievement of a V-0 rating in an unfilled epoxy system with a low, 2.5% P level. These properties, combined with low water-uptake; compatibility, with low Dk and Df resins and low CTE both before and after Tg, enable the use of Material A in a variety of applications.
Initially Published in the IPC Proceedings
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