The Prevention and Removal of Absorbed Chemicals in Ceramic Filled PTFE Composites
●RT/duroid® 6000 Series, RO3000® Series, and RO3200™ Series High Frequency Laminates are polytetrafluoroethylene (PTFE) composites containing a large volume fraction (>50%) of ceramic filler particles. The high filler loading provides RT/duroid 6002, RO3000 series, and RO3200 series laminates with a low Z-axis coefficient of thermal expansion (CTE) for excellent plated through-hole reliability and an in-plane CTE closely matched to copper for good dimensional stability. The filler loading in RT/duroid 6006 and 6010 achieves a high dielectric constant allowing for reduced circuit size.
●The material’s high filler loading also contributes to approximately 5 volume percent porosity. The microvoids in the composite appear to exist at the filler-PTFE interface but are not detectable in cross-sections, even with scanning electron microscopy. Because of the low surface energy of PTFE and the treated ceramic filler, the microvoids do not result in high water absorption. However, low surface tension liquids such as organic solvents and surfactant laden aqueous solutions can penetrate the pores.
●Since PTFE and the ceramic filler are inert to most process chemicals, liquid uptake simply fills microvoids but does not change the physical properties of these laminates. However, it is critical that volatiles that have penetrated the composite be removed prior to exposing the boards to high temperatures (e.g. bonding operations, Sn/Pb reflow, etc.) Parts should also be thoroughly rinsed immediately following exposure to process chemicals to ensure that non-volatile dissolved materials are not left behind when the parts are baked.
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PTFE 、 Ceramic Filled PTFE Composites 、 High Frequency Laminates 、 poly tetra fluoroethylene (PTFE) composites |
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Technical Documentation |
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Please see the document for details |
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English Chinese Chinese and English Japanese |
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2017/08/01 |
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Publication#92-495 |
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73 KB |
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