Parallel Plate Capacitance Testing for Packaging Core Dielectrics
Parallel plate capacitance testing extracts packaging core permittivity from 100 Hz to 1 GHz by applying guarded electrodes to etched, preconditioned coupons.
Core Laminate Qualification
Evaluation Standard
Formal testing procedures established by industry standards define the baseline performance for copper-clad dielectric materials used in multi-layer board fabrication. Through the process of core laminate qualification, manufacturers verify that the raw materials meet specified electrical and mechanical limits before production begins. This evaluation confirms that the fiberglass reinforced epoxy base can withstand subsequent chemical and thermal processing.
Thermal Stress
Subjecting the sample to multiple solder simulation cycles reveals the ability of the material to resist delamination and blistering under intense thermal loads. During core laminate qualification, the material undergoes thermal stress testing at temperatures exceeding two hundred and eighty degrees Celsius. This stress simulates the conditions encountered during lead-free reflow assembly where rapid expansion can rupture weak resin-glass interfaces.
Laboratory technicians measure the time to delamination using thermomechanical analysis to ensure the long-term reliability of the substrate. If the material exhibits cracking or separation of the copper foil from the dielectric layer, the batch is rejected.
Dimensional Stability
Measuring the changes in board size after etching and baking ensures that the copper layers will align correctly during subsequent lamination steps. During core laminate qualification, the physical movements of the sheet are recorded to calculate the registration tolerances across multiple layers. High-density designs with small annular rings cannot tolerate material that shrinks or expands excessively during processing.
Standardized measurement protocols specify the exact positions where the distance between registration targets is tracked. Any material exceeding the maximum allowed movement is excluded from use in high-precision multi-layer boards.