Isothermal PCB Slotting Geometry Optimization for Sub-PPM Precision Voltage References
Optimized PCB slotting isolates precision voltage references from board strain and thermal gradients, cutting drift below one part per million.
To-99 Header
Metal Can Isolation
Eight-pin hermetic metal-can transistor outlines certified to MIL-STD-1835 standards provide electromagnetic shielding and environmental isolation for ultra-low-drift analog integrated circuits. Precision system integrators select the to-99 header to house ovenized voltage references and low-bias current operational amplifiers. The grounded Kovar metal can blocks ambient electrostatic field interference from disturbing high-impedance internal circuit nodes.
Glass-to-metal seals isolate individual leads passing through the heavy steel header base plate. Pin layout geometries conform to standard circular patterns for socket or direct board mounting.
Pin Configuration
Circular eight-lead pin arrangements allow flexible terminal assignments for power, signal, and guard rings. Grounding pin eight to the metal case of the to-99 header creates an integral Faraday shield surrounding sensitive silicon dies. Terminal guard rings connected to driven guard voltages prevent board leakage currents from reaching input pins.
Socket insertion forces must remain controlled to avoid cracking glass seals.
Hermetic Sealing
Glass-to-metal seals prevent atmospheric moisture penetration and chemical contamination over decades of field service. Hermetic integrity in the to-99 header prevents moisture-induced leakage currents across input terminals. Helium leak testing verifies seal integrity down to standard aerospace leak rate thresholds.
Thermal Mass
Heavy metal headers increase total package thermal mass, dampening rapid ambient temperature spikes. Thermal time constants lengthen when mounting the package in still air environments.