A Review of Epoxy Materials And Reinforcements, Part 2

摘要

Halogen-free resins. Flame-retardant FR-4 epoxy laminates using tetrabromobisphenol-A (TBBPA) have been the industry standard for many years. However, negative perceptions of brominated flame-retardants have recently led to the development of various halogen-free materials. Table 4 compares thermomechanical and electrical properties of four halogen-free materials with standard FR-4 and high-Tg FR-4. The standard and halogen-free base materials exhibited decreased copper peel strengths and increased Tg. None of the halogen-free laminates investigated exhibited influence of thermal stress on copper peel strength. The solder shock testing as a measure of the thermal resistance of the base material showed that all tested laminates met the minimum requirement (1 x 288℃, 10 sec.). With an extension of the testing time to 60 sec., one of the investigated materials exhibited measling. The repeated solder shock confirmed the poor thermal stability of this and of another halogen-free laminate. In regard to the higher soldering temperatures for lead-free applications, and therefore the high thermal stability requirement of the base material, the selection of a halogen-free laminate suitable for specific applications is crucial.