RoHS, the lead-free directive, restricts the use of hazardous materials in electronics manufacturing. When complying with this regulation, manufacturers must use lead-free solder, which operates at higher temperatures—270°C instead of the traditional 250°C used with lead-based solder.
Temperature Impact on Materials
This 20-degree temperature increase makes PCB material selection critical to avoid delamination or “pop-corning” during the soldering process. The key factor to consider is the glass transition temperature (Tg) of the laminate material.
Glass Transition Temperature (Tg) Requirements
- Traditional lead-based soldering: Tg 130-140°C was typically sufficient
- Lead-free processes: Now typically require Tg 150°C or Tg 170°C materials
Moisture Considerations
Trapped moisture in laminates can cause damage during the higher-temperature lead-free soldering process. To prevent this:
- Store PCBs and components properly to minimize moisture absorption
- Pre-bake components and boards before soldering when necessary
- Consider using moisture-barrier packaging for sensitive materials
Material Selection
Selecting the appropriate material for your specific application is crucial for RoHS compliance. The right choice depends on:
- The complexity of the assembly process
- The number of reflow cycles required
- The operating environment of the final product
- Cost considerations
For guidance on selecting the right materials for your RoHS-compliant PCB design, please contact our team.
Related Articles
- PCB Materials and Laminates Guide – Tg ratings and material specifications
- How Multilayer PCBs Are Made – Understanding the lamination and soldering processes
- PCB Designer’s Tips – Material selection considerations
Questions about RoHS-compliant materials? Request a quote – we’ll recommend the appropriate Tg material for your assembly process.