XinshunPCB Frequently Asked Questions

To ensure zero out-of-box failures, we offer a comprehensive testing suite tailored to project complexity:
In-Circuit Testing (ICT): Bed-of-nails electrical fixtures verifying component values, tolerances, and circuit continuity.
Flying Probe Testing (FPT): Fixtureless electrical testing suitable for high-density prototypes and small batches.
Functional Circuit Testing (FCT): Custom test jigs powering up the board to execute automated firmware loading, I/O signal simulation, RF calibration, and communication bus checks.
Environmental Stress Screening (ESS): Thermal cycling, burn-in chamber testing, and multi-axis vibration testing.

IPC-A-610 Class 3 limits BGA voiding to ≤ 15%. XinshunPCB typically suppresses voiding to < 8% to 10%. We accomplish this through: (1) Designing laser-cut electro-polished stencils with optimized aperture patterns (window pane cross-hatching for ground slugs); (2) Formulating high-activity, low-voiding Type 4/Type 5 solder pastes; and (3) Running multi-zone reflow ovens under a controlled Nitrogen (N2) atmosphere (< 100 ppm O2 residual) with tailored thermal soak zones to facilitate complete flux degassing prior to liquidus transition.

We enforce a three-tier inline automated quality inspection process to intercept defects before they can propagate:
In-Line 3D SPI (Solder Paste Inspection): Measures 100% of solder paste deposit volume, height, area, and coplanarity immediately after stencil printing, intercepting paste bridging or insufficient volume.
In-Line 3D AOI (Automated Optical Inspection): Inspects post-reflow component presence, polarity, alignment skew, tombstoning, and solder joint wetting using multi-frequency structured light.
High-Resolution 3D Micro-Focus X-Ray: Penetrates non-visible joints beneath BGA, CSP, and QFN packages to inspect internal wetting, bridging, and solder ball void percentages.

Our high-speed automated placement lines (Panasonic NPM / Yamaha YSM series) achieve high-accuracy placement with repeatability within ±0.03 mm (Cpk ≥ 1.33). We reliably assemble micro passives down to 01005 (0402 metric) and fine-pitch packages down to 0.30 mm pitch micro-BGAs, WLCSPs, and 0.35 mm pitch QFNs. Lead coplanarity and component alignment are verified in real time using multi-angle laser optical sensors prior to board touch-down.

We offer flexible procurement and assembly models to match your supply chain strategy:
Full Turnkey: XinshunPCB manages the entire lifecycle—fabricating bare boards, procuring 100% genuine components from authorized distributors (e.g., Digi-Key, Mouser, Arrow, and original factory direct lines), fabricating solder paste stencils, SMT/THT assembly, and final functional verification.
Partial Turnkey (Combo): You supply specialized, proprietary, or custom ICs/firmware chips, while we procure all standard passives, connectors, and bare boards.
Consigned (Kitted): You deliver all raw components and circuit boards, and XinshunPCB provides high-precision assembly, inspection, and testing services.

For LED lighting applications, we offer high-reflectivity liquid photoimageable (LPI) white solder masks with > 85%–92% optical reflectivity that resist yellowing under high thermal baking and long-term UV radiation exposure. For industrial power and motor control boards, standard dark green, matte black, or blue solder masks are available. Our standard surface finishes include Electroless Nickel Immersion Gold (ENIG) for fine-pitch pads and flat thermal interfaces, Lead-Free HASL for cost-effective through-hole soldering, and ENEPIG for wire-bondable Chip-on-Board (COB) applications.

Thick metallic substrates present unique mechanical machining challenges. We employ high-torque CNC milling centers running diamond-coated carbide router bits with active air-oil mist cooling to deliver burr-free edges and tight dimensional outline tolerances within ±0.1 mm. For panelization, we use automated high-precision V-scoring equipment calibrated to maintain accurate residual web thickness. Furthermore, all panels undergo controlled hot-press flattening procedures to ensure overall panel warpage strictly complies with < 0.5%, guaranteeing flush mechanical contact with external heatsinks.

Fabricating double-sided metal-core boards with through-hole connectivity requires preventing electrical shorts to the conductive metal core. We first CNC-drill oversized clearance holes through the aluminum or copper base plate. These cavities are vacuum-filled with a specialized high-voltage dielectric epoxy resin and thermally cured. We then precision-drill secondary holes through the center of the cured epoxy plugs, chemical-desmear, and electroplate copper down the hole barrel. This creates fully functional plated through-holes (PTH) insulated from the metallic core.

We offer a full spectrum of dielectric isolation layers ranging from 1.0 W/m·K, 2.0 W/m·K, 3.0 W/m·K up to 8.0 W/m·K ceramic-filled polymers. To ensure complete dielectric safety in high-voltage circuits, every production panel is subject to 100% automated Hipot dielectric withstand testing. We support test parameters from 3000V AC up to 6000V AC (or > 4000V DC) with leakage current limits strictly configured to < 0.5 mA, fully conforming to UL 796 and IPC-4101 standards.