Precision Double-Sided PCB Assembly
for Compact, High-Density Electronics

We mount components on both sides of each double-sided PCB using automated SMT systems that operate at up to 60,000 placements per hour.

Placement accuracy is maintained below ±30 µm with fiducial-based alignment that supports dual-sided mounting of 0201 passives, BGAs, QFNs, and fine-pitch ICs.

During the second pass, boards are flipped using vacuum clamping fixtures to maintain orientation and protect previously mounted devices. All placements are verified inline through SPI and post-reflow AOI.

Adhesive retention is applied selectively to components on the underside to prevent gravity-induced displacement during second-pass reflow.

We use temperature-cured red glue placed at ±0.05 mm accuracy between component leads, ensuring stability without contaminating solder pads.

For high-mass or unevenly shaped parts, this adhesive strategy enables full second-side reflow soldering without defect risk.

We apply red adhesive such as Henkel Loctite 3609, centrally positioned to avoid pad contamination, and cure it at 180 °C before the second reflow cycle begins.

We operate two separate SMT production lines to isolate lead-free and standard tin-lead assemblies.

This infrastructure allows us to process RoHS-compliant builds using SAC305 alloy in a nitrogen reflow oven while maintaining IPC-A-610 Class 2 or 3 quality benchmarks.

If required, lead-free soldering is paired with low-residue flux and pre-bake cycles to mitigate moisture sensitivity.

Clear designation of the board type ensures no material cross-contamination across double-sided PCB assembly runs.

Each side of the double-sided PCB assembly receives its own reflow cycle, optimized for the thermal demands of the component layout and copper weight.

Instead of using generic profiles, we adjust temperature ramp rates, peak hold times, and cool-down slopes to limit mechanical stress across the board.

These adjustments prevent warpage, especially on boards with large thermal gradients or asymmetrical placement. For stacked or hybrid layers, we simulate thermal response and validate each reflow soldering profile before production begins.

Nitrogen inerting is used during reflow to suppress oxidation, improving solder wetting and joint reliability across both passes. Typical profiles reach peak temperatures of 235 to 245 °C for SAC305, with soak zones maintained at 150 to 180 °C to activate flux and ensure even thermal exposure.

Inspection is integrated directly into the assembly flow, beginning with AOI after the first reflow and repeating after the second.

Our dual-camera AOI systems detect placement shifts, tombstoning, and solder bridging across both board sides. For hidden joints under BGAs or LGA packages, we use 3D X-ray imaging to identify voids, cold joints, or insufficient solder fill.

This dual-layer inspection protocol provides defect traceability for every double-sided printed circuit board we ship.

Boards that combine SMT and through-hole parts are processed with selective soldering or hand assembly, depending on layout and clearance.

Heavier connectors or legacy components are inserted post-reflow, then soldered using wave soldering or controlled heating tools. Component leads are checked for pad alignment and lead co-planarity before soldering begins.

In boards with dense via arrays, our pre-assembly checks validate annular ring clearance and copper plating continuity through the drill stack.

We offer microvias down to 3 mil diameter, blind/buried vias, and via-in-pad construction for double-sided SMT and HDI builds.

All via holes are mechanically drilled and plated using pulse electroplating to maintain wall uniformity ≥25 µm.

For stacked vias, we validate alignment through cross-section analysis and control aspect ratios up to 40:1. These structures allow high routing density without increasing board layer count.

We support full-cycle double-sided PCB board production from as few as five prototypes to orders exceeding 10,000 units.

Panel sizes range from 50 mm × 50 mm up to 610 mm × 508 mm, with finished thicknesses from 0.5 mm to 4.5 mm and copper weights up to 28 oz.

Build tracking is maintained through our MES platform, and every circuit board is verified through optical inspection and electrical test prior to packaging.

Flexible lead times allow 2 to 3 day expedited runs or standard 7 to 10-day delivery based on material availability and volume.

Our SMT lines interface with real-time MES dashboards and inline AOI/X-ray systems for closed-loop feedback and zero-defect tracking.

Data capture supports batch-level traceability, pass/fail analytics, and predictive process tuning.