Suppression of Multilayer Plane Cavity Resonances Using Peripheral via Arrays
Peripheral via arrays eliminate multilayer PCB cavity resonances by constructing an electromagnetic fence that suppresses high-frequency edge radiation.
Copper Barrel Thickness
Measurement Standard
Vertical metal deposition inside a drilled hole wall defines this specification for printed circuit board fabrication. Copper barrel thickness describes the quantity of conductive material plated upon the interior circumference of a through hole to ensure electrical continuity between board layers. Standard manufacturing tolerances dictate a minimum value, typically measured in micrometers, to prevent cracking during thermal cycling or soldering operations.
Plating Integrity
Achieving a uniform copper barrel thickness requires precise control of the electroplating process within the electrolyte bath. Operators balance current density and agitation cycles to maintain consistent growth rates across the hole geometry. Insufficient accumulation at the center of the board leads to weak interconnections that fail under the mechanical stress of thermal expansion.
Variations between the surface copper and the interior deposit occur when additive chemistry or electrode positioning prevents even distribution. Excess plating at the hole entrance constricts the opening, hindering the assembly of components with tight lead tolerances.
Acceptance Criteria
Microsection analysis provides the definitive method to verify that copper barrel thickness meets established requirements for a specific board class. Technicians examine a cross section of a sacrificed sample under high magnification to confirm the metal integrity throughout the entire length of the via. Acceptable hardware exhibits no voids or fractures within the plated wall structure.
High reliability applications demand a thicker deposition than standard consumer electronics to withstand repeated exposure to extreme temperature shifts. Reliable hole structures support the longevity of the final product.