Expert in Comprehensive PCBA Full-Process Services
BMS sampling resistor mounting offset, leading to inaccurate detection?
Symmetrical pad design, micro suction nozzle with dual-vision alignment, AOI inspection, and rework via hot-air reflow for misaligned components.
Poor connector heat dissipation and high contact resistance?
The heat-sink pad features full-array vias, paired with high-thermal-conductivity solder paste or thermally conductive silicone grease; contact resistance is measured at ≤50 mΩ, and temperature rise is tightly controlled.
Poor corrosion resistance of solder joints—unable to pass the damp-heat test?
Moisture- and heat-resistant solder paste, plasma cleaning, and thorough post-soldering residue removal ensure dense, reliable solder joints.
Are defects more common in areas with high and low voltage proximity and small solder pads?
Ensure the high- and low-voltage clearance is ≥2 mm; adjust the steel stencil or modify the PCB layout to conduct first-article testing and thereby mitigate insulation risks.
Cracking of solder joints after exposure to damp heat or high/low temperature?
Use resilient solder paste; apply extra solder to critical joints, perform underfill when necessary, and re-solder cracked components after optimizing process parameters.
High-voltage test breakdown or insulation failure?
Remove excess solder balls and residues; thicken the solder mask in high-voltage areas; measure insulation resistance to ensure it is ≥100 MΩ; any nonconforming units must be reworked.
Has the damp-heat resistance decreased after repair?
Specialized solder paste combined with a dedicated reflow profile ensures thorough removal of residues, followed by application of a three-proof coating and individual damp-heat testing.
Bubbles and lifting after three-proof coating?
Dry at 80°C for 30 minutes to remove moisture and residues; apply a coating thickness of 0.1–0.2 mm, cure in stages, and reapply over any blistered areas.
After soldering, there are frequent instances of cold or false solder joints, resulting in unstable signals or intermittent signal loss upon power-up. How should this be addressed?
First, select automotive-grade lead-free solder (such as SAC305) and a low-residue high-temperature flux; avoid chlorine-containing formulations to prevent corrosion. Next, adjust the reflow profile—specifically the temperature and dwell time at each stage—based on the thermal tolerance of the components (e.g., ceramic capacitors and power chips) to ensure complete melting and wetting of the solder without damaging the parts. Prior to reflow, use plasma cleaning to remove oxide layers from pads and leads, and then perform X-ray inspection of the solder joints: rework any voids or cold joints, and promptly replace any contaminated components.
Pin bridging and solder balls—especially in high-density chips—can easily cause short circuits. What should be done?
Use high-precision laser cutting to fabricate the steel stencil; when the pin pitch is ≤0.5 mm, reduce the stencil aperture by 10%–15% and round the edges to minimize solder volume. Calibrate the pick-and-place nozzle to control mounting pressure and accuracy, ensuring that component placement deviation does not exceed ±0.1 mm. During reflow soldering, slow down the heating rate in the soak zone to reduce solder turbulence. After soldering, use an anti-static desoldering tape to remove any solder balls; do not use sharp tools to scrape the solder pads, as this could damage the circuit traces.
A professional EMS (Electronic Manufacturing Service) company dedicated to providing customers with end-to-end manufacturing services, including SMT, DIP, post-soldering, assembly, adjustment, complete-unit testing, and finished-product packaging and shipment.
No.19 ,CHUANG YE 1ST RD,NINGBO,FREE TRADE ZONE(WEST),R.P.O.C