Dry Goods Sharing | Globalwell Explains 17 Common Soldering Defects & Judgment Standards in SMT Reflow Soldering

2026-04-28 09:57:37
Source：PCB Assembly
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Dry Goods Sharing | Globalwell Explains 17 Common Soldering Defects & Judgment Standards in SMT Reflow Soldering

After SMT reflow soldering, various soldering defects may occur. These welding problems will directly or indirectly affect the overall quality, electrical stability and service life of PCBA products.

Standardized defect names and judgment criteria help operators and quality inspectors quickly identify and classify abnormalities. It also provides a clear industry basis for process adjustment, production improvement and standardized operation.

Once any soldering defect is detected during production, rework and remedial measures must be implemented strictly to prevent defective products from outflowing and ensure production quality.

Below, Globalwell sorts out and explains 17 frequent soldering defects in SMT mass production:

Solder Bridging
Unwanted solder connection between component terminals, adjacent solder joints, circuits and vias, which easily causes short circuit failure.
Tombstoning (Manhattan Effect)
One end of two-terminal chip components lifts off the pad after reflow soldering, causing the component to stand diagonally or vertically, mainly caused by uneven heating and inconsistent wetting.
Billboarding
Chip components turn sideways and contact the PCB pad with the side face, resulting in abnormal mounting and poor soldering.
Offset / Misalignment
Components shift horizontally with terminals and pins deviating from pads, easily leading to insufficient solder, cold solder and mechanical fracture risks.
Flipped Component
Chip components are mounted upside down, affecting appearance and subsequent assembly.
Solder Beads
Tiny spherical solder scattered around components and solder joints after reflow, with strong concealment and potential hidden short-circuit risks.
Cold Solder Joint
Insufficient reflow temperature and heating lead to incomplete solder melting and wetting. No stable metal alloy layer is formed. Cold solder joints are loose and prone to poor contact in long-term use.
Wicking
Solder climbs upward along component pins and accumulates on the component body, resulting in insufficient solder or empty solder on PCB pads and weak connection strength.
Polarity Reversal
Polarized components such as diodes, electrolytic capacitors and ICs are mounted in the wrong direction, directly causing functional failure.
Voids / Bubbles
Flux gas cannot be completely discharged before solder solidification, forming closed holes inside solder joints and reducing structural strength and heat dissipation performance.
Pinholes
Tiny pin-shaped holes on the solder surface, usually caused by damp PCB, rapid temperature rise and abnormal flux volatilization.
Cracking
Solder joints crack due to thermal cycling, mechanical external force and internal stress, which may cause open circuit failure in long-term temperature changes.
Solder Tips
Sharp thorn-shaped solder protrusions on the edge of solder joints, resulting in rough appearance and assembly hazards.
Excessive Solder
Overabundant solder accumulation covers component pins and pad outlines, easy to cause flux residue and hidden quality risks.
Open Solder
Component terminals and pins are completely separated from pads without effective welding connection, belonging to serious open-circuit defects.
White Marks / Weave Exposure
Separation between glass fiber and resin inside PCB substrate, showing white dots or cross patterns, mostly caused by high temperature stress and damp base material.
Dull Solder Joints
Caused by excessive temperature, over-volatilized flux and repeated rework. The solder surface is dark, loose and porous with high brittleness and poor long-term reliability.

Conclusion

There are various types of reflow soldering defects, involving PCB design, component incoming quality, solder paste management, mounting accuracy and reflow profile setting.

Mastering the standard definition and appearance features of welding defects is the foundation of SMT quality control, as well as the key to optimizing processes, reducing defect rates and improving production first-pass yield.

With years of experience in SMTmounting and PCBA processing, Through standardized solder paste management, optimized reflow temperature curve, AOI full inspection and manual re-inspection, we effectively reduce common defects such as bridging, tombstoning, empty solder and cold solder.

With standardized operation and stable quality, Globalwell provides customers with cost-effective and reliable one-stop SMT processing services.

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