5 — Silixon-PCB

Printed Circuit Board

What It Is

Silixon-PCB is Hardin Labs' next-generation printed circuit board substrate designed to replace conventional FR-4 epoxy-glass laminate with a Silixon ceramic-polymer composite dielectric that offers dramatically superior thermal performance, radiation hardness, mechanical stability, and dielectric uniformity. While FR-4 begins to delaminate and warp above 130 °C, Silixon-PCB maintains full structural and electrical integrity up to 600 °C continuous service temperature and survives short-term excursions above 1,000 °C — enabling circuit boards to operate inside environments previously inaccessible to conventional electronics.

Construction

The substrate is a multi-layer laminate in which each dielectric layer is a thin Silixon-PDC film formed by doctor-blade casting, followed by partial pyrolysis to a semi-crystalline state that retains mechanical flexibility for lamination. Copper and silver traces are deposited by either standard photolithographic etching or direct-write aerosol jet printing. Via interconnects are filled with a galinstan paste that sinters at 200 °C into a dense, void-free metallic plug with contact resistance below 1 mΩ. The board is fully pyrolyzed as a laminate assembly at a final temperature calibrated to the trace metal's melting point minus a safety margin, producing a monolithic ceramic-metal composite with no delamination interface.

Electrical Performance

The Silixon ceramic dielectric has a relative permittivity (εᵣ) of approximately 4.5–6.0 at 10 GHz, with a loss tangent below 0.003 — significantly better than FR-4 at high frequencies and competitive with specialized PTFE-ceramic microwave substrates. Signal integrity at mmWave frequencies above 30 GHz is preserved across the entire board area without the phase velocity dispersion that afflicts woven glass-fiber substrates. These properties make Silixon-PCB the natural substrate for the GNDS high-frequency read/write drivers, the HLED photonic control electronics, and the DART aircraft's radar and communications modules.

Reliability and Environmental Resistance

Silixon-PCB is hermetic — it does not absorb moisture or outgas organics in vacuum environments. Its coefficient of thermal expansion (CTE) is tunable from 3 to 8 ppm/°C through dopant chemistry, allowing it to be closely matched to silicon die, gallium nitride power devices, or sapphire optical components, virtually eliminating solder-joint fatigue in thermally cycling environments.