I'm thinking of building and selling a product which uses a DC-DC isolator. I've been prototyping with Recom RI3 3W Isolated DC-DC Converter Through Hole, Vin 5 V dc, Vout 9V dc, I/O isolation 1kV. The latest datasheet suggests an EMC filter using a 10uF 100V MLCC capacitor to meet EN55032. These capacitors are expensive, and so might affect the viability of my product.
For my own purposes, the prototype works fine both without a filter, and with an aluminium capacitor in place of the MLCC one. Are there other types of capacitor I could use which might enable me to achieve FCC and CE compliance while keeping down the cost of components?