Utilizing German multi-beam CO2 and UV laser systems, we achieve microvia hole diameters down to 50 µm to 75 µm (2 to 3 mil). Our standard microvia aspect ratio is maintained at 0.8:1 to 1:1, which ensures optimum chemical fluid exchange during desmear and enables 100% void-free electroplated copper filling. For mechanical buried core vias, we support drill sizes down to 0.15 mm (6 mil).

VIPPO (Via-in-Pad Plated Over), also known as POFV (Plated Over Filled Via), is a process where microvias or through-vias located directly inside component solder pads are vacuum-plugged with non-conductive epoxy resin, thermally cured, planarized flush via ceramic grinding, and electroplated with copper. This creates a flat, solid metallic surface (< 15 µm coplanarity variation), eliminating solder drainage into via barrels during reflow and allowing microvias to sit directly beneath 0.30 mm to 0.40 mm pitch BGA pads.

We achieve fine line width and spacing down to 40 µm / 40 µm (1.6 mil / 1.6 mil) on volume production using German Laser Direct Imaging (LDI) and automated vacuum etching compensation systems. For high-speed digital and RF lines, we simulate stackups using Polar SI9000 field solvers and maintain single-ended (50Ω) and differential (90Ω, 100Ω) controlled impedance tolerances strictly within ±5%, verified 100% via panel-level Time-Domain Reflectometry (TDR) coupon testing.

Stacked microvias can be vulnerable to interface separation under high thermal expansion ($z$-axis CTE). To ensure long-term interconnect reliability: (1) We apply plasma dry etching combined with chemical permanganate desmear to clean microvia bottoms down to the target pad; (2) We run automated vertical continuous plating (VCP) with specialized copper filling additives to yield dimple depths < 5 µm; and (3) Every production batch undergoes solder float testing (288°C for 10 seconds, 3 cycles) and metallurgical microsectioning under IPC-6012 Class 3 criteria.

All HDI boards are manufactured and verified to IPC-A-600 Class 2 and Class 3 standards. The inspection gate includes:
100% Electrical Netlist Testing: High-density double-sided flying probe testing checking continuity and isolation down to low-resistance thresholds.
Automated Optical Inspection (AOI): Multi-spectral AOI inspecting inner and outer fine lines, spacing, and microvia annular rings against customer Gerber/ODB++ datasets.
High-Resolution 3D X-Ray Inspection: Verifying layer-to-layer microvia alignment, registration, and stacked via barrel fill integrity.