Authored By:
Jooho Shin, Sooim Jung, Minsu (Tim) Lee
R&D Center, Doosan Cooperation
Electro-Materials BG
Yongin, S. KOREA
Summary
The mobile communication devices such as cell phones require high speed transmission of large volume data as well as reduction in size and weight. When signal is transmitted in high speed and frequency on PCB, signal integrity becomes a problem. This problem is getting worse as the transmission becomes faster and larger. Therefore, materials with low Dk/Df are need for high frequency board. Another requirement for current communication board is environmental friendliness, which is lead and halogen free. As for laminates, there are some low Dk/Df ones and many halogen free ones.
However, material with both is hard to find, quite expensive and difficult to process. Therefore, communication industry is looking for new materials. To meet this demand, a novel halogen free material with low Dk/Df, DS-7402D, has been developed. A hydrophobic epoxy resin was used as base resin to improve the dielectric properties. In addition, a phosphorus containing resin was applied as a hardener and halogen free flame retardant.
The resulting material has better dielectric properties, Dk of 3.9 and Df of 0.01,than those of conventional FR-4. It also shows an excellent thermal stability, Td higher than 380C, which makes it suitable for lead-free process. The other properties of this material, such as copper adhesion, modulus and water absorption will be presented.
Conclusions
New material technology gives performance advantages over the currently available non-halogenated FR-4 resin system. New material has lower Dk and Df as compared to most non-halogen offerings. In addition, this new resin system provides more thermal resistance than conventional high Tg materials. Thus, this halogen free low Dk material is a viable candidate for high speed PCB and lead-free solder applications
Initially Published in the IPC Proceedings
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