Resin Content Percentage

Fabrication Interaction

High resin levels are required to fill the gaps in designs with thick copper planes or buried vias. If the resin content percentage is too low, the board may suffer from delamination or internal voids. Conversely, too much resin can lead to excessive thickness variation and poor dimensional stability.

Fabricators must balance these factors based on the specific requirements of the stackup.

Signal Performance

The electrical properties of a substrate are a weighted average of the resin and the glass reinforcement. A higher resin content percentage generally results in a lower dielectric constant because resin typically has a lower permittivity than glass. This property is used to fine-tune the impedance of signal traces without changing the copper geometry.

Reliability is also improved because a resin-rich environment provides better protection against conductive anodic filament growth. Testing for moisture absorption is performed to ensure the polymer system remains stable over time.