Selecting Dielectric Substrates for High Speed Multilayer Stackup Design
Selecting dielectric substrates requires balancing dissipation factor, glass weave uniformity, foil roughness, and panel yields to meet high-speed impedance targets.
Slash Sheet 126
Specification Document
Technical requirements for high performance laminates are categorized into numbered pages within the IPC-4101 standard. The slash sheet 126 defines the properties for epoxy glass materials that are designed to withstand high temperatures and lead-free soldering processes. These materials must maintain their structural integrity even when exposed to the intense heat needed for modern assembly.
Thermal Stability
Materials covered by this specification have a glass transition temperature of 170 degrees Celsius or higher. A slash sheet 126 material is chosen for industrial and automotive applications where the board will face repeated thermal stress or operate in hot environments. The specification also sets limits on how much the material can expand in the z axis when heated.
This control prevents the copper plating in the through-holes from cracking during the manufacturing process.
Material Selection
Procurement processes use these identifiers to ensure that the laminate from different suppliers will perform the same way on the production line. The slash sheet 126 designation guarantees that the resin system and the glass reinforcement meet the minimum safety and performance levels. Using a standardized sheet number simplifies the communication between the designer and the fabricator during the quoting process.
A certificate of compliance must accompany every batch of material to verify these properties.