Lead Free Assembly and ROHS Compliant PCB Materials
All Nelco Electronic and PCB Materials are RoHS Compliant:
- RoHS Compliance Letter for Nelco Materials
- REACH Letter for Nelco Materials
- Conflict Minerals Statement
- EAR ECCN Letter
- The Nelco Electronics Material Selection Guide provides a comparative material overview including CAF and lead-free designations for electronic materials.
- Internal testing has shown all Nelco materials to be RoHS compliant. Following are some additional independent laboratory test results for key materials:
- Mercurywave™ 9350 Microwave Performance, Modified Epoxy
- N4000-6 / N4000-6 FC High-Tg Multifunctional FR4 Epoxy
- N4000-7 Low-CTE Multifunctional Epoxy
- N4000-29 Lead-Free, High-Tg Multifunctional Epoxy
- N4000-12 High-Speed, Low-Loss, Lead-Free Compatible Epoxy
- N4000-13 High-Speed, Low-Loss Epoxy
- N4800-20 High-Speed, Multifunctional Epoxy
- N9000 PTFE / RF Microwave Materials
Qualities to consider when choosing a lead-free circuit board material:
Glass transition temperature (Tg), coefficient of thermal expansion (CTE) and decomposition temperature (Td) are key data points to consider when choosing a substrate material for a lead free assembly compatible design.
- The Tg of a resin system is the temperature at which the material transitions from a rigid state into a softened state. Tg is the material property typically used by the industry to compare the thermal robustness of a laminate. Though a contributor to lead-free compatibility, Tg alone is not sufficient to indicate if a material is suitable for lead free applications.
- CTE is a measure of the material expansion below and above the Tg and generally expressed as parts per million (ppm). A lower CTE generally indicates increased plated through hole (PTH) reliability. A low CTE is a strong indicator of lead free compatibility and high temperature solder reliability.
- Td is derived by measuring the weight loss of the sample versus temperature. Td is important when assessing thermal survivability, particularly during high temperature lead-free processes. A material’s decomposition temperature is the temperature at which the material weight changes by 5%.
Lead-Free Technical Papers:
- Evaluating Laminates for High Temperature Assembly By Silvio Bertling as printed in The Board Authority, September 2005.
- PWB Dielectric Substrates for Lead-Free Electronics Manufacturing By Douglas Leys and Steven P. Schaefer as presented at IPC Expo 2003.