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  • 16 kinds of PCB weld defects

    Every day has learned a little of PCB and I believe I can become more and more professional in my work. Today, I want to introduce 16 kinds of PCB weld defects from appearance characteristics, hazards, causes.

     

    1.Pseudo Soldering

    Appearance characteristics: there is an obvious black boundary between solder and component lead or copper foil, and the solder is concave to the boundary

    Hazards: cannot work properly

    Causes: 1) the lead wires of components are not well cleaned, not well tinned or oxidized.

    2) PCB is not clean, and the quality of flux sprayed is not good

     

    2. Solder accumulation

     

    Appearance characteristics: Solder joints are loose, white and dull.

    Hazards: mechanical strength is insufficient, may virtual welding

    Causes: 1) poor solder quality.2) insufficient welding temperature.3) when the solder is not solidified, the lead of the component becomes loose.

     

    3.Too much solder

     

    Appearance characteristics: The solder face is convex

    Hazards: Waste solder and may contain defects

    Causes: solder withdrawal is so late

     

    4. Too littler solder

     

    Appearance characteristics: The welding area is less than 80% of the welding pad, and the solder does not form a smooth transition surface

    Hazards: mechanical strength is insufficient,

    Causes: 1) poor solder fluidity or premature solder withdrawal. 2) insufficient flux.3) welding time is too short.

     

    5. Rosin welding

     

    Appearance characteristics: There is rosin residue in the weld

    Hazards: the harm intensity is insufficient, the conduction is bad, possibly when on and off

    Causes:1) excessive welding machine or failure.2) insufficient welding time and heating.3) surface oxide film is not removed.

     

    6. hyperthermia

     

    Appearance characteristics: The solder joint is white, without metallic luster, the surface is rough.

    Hazards: It is easy to peel off the welding pad and reduce the strength

    Causes: he soldering iron is too powerful and the heating time is too long

     

    7. cold welding

     

    Appearance characteristics: the surface into tofu slag particles, sometimes may have cracks


    Hazards:
    Low trength and poor electrical conductivity

    Causes: the solder dithers before solidification.

     

    8. Infiltrating the bad

     

    Appearance characteristics: the interface between solder and welding too large, not smooth
    Hazards: Low intensity, impassable or intermittent

    Causes: 1) welding parts are not cleaned 2) insufficient flux or poor quality.3) welding parts are not fully heated.

     

    9. dissymmetry

     

    Appearance characteristics: the solder plate is not full
    Hazards: Insufficient harm intensity

    Causes:1) poor solder fluidity.2) insufficient flux or poor quality.3) insufficient heating.

     

    10. Losse

     

    Appearance characteristics: the lead wires or components can be moved
    Hazards: bad or don’t conduction

    Causes: 1) lead movement causes void before solder solidification.2) lead is not properly handled (poor or not infiltrated)

     

    11. Solder projection

     

    Appearance characteristics: appear cusp

    Hazards: Bad appearance, easy to cause bridging

    Causes: 1) too little flux and too long heating time.2) improper evacuation Angle of the soldering iron

     

    12. Bridge connection

     

    Appearance characteristics: Adjacent wire connection

    Hazards: Electrical short circuit

    Causes: 1) excessive solder. 2) improper evacuation Angle of the soldering iron

     

    13.Pin Holes

     

    Appearance characteristics: Holes are visible in visual or low power amplifiers

    Hazards: Insufficient strength and easy corrosion of solder joints

    Causes: the gap between the lead wire and the hole of the welding pad is too large.

     

    14.Bubble

     

    Appearance characteristics: the root of the lead wire has spitfire solder uplift and internal cavity

    Hazards: Temporary conduction, but it is easy to cause bad conduction for a long time

    Causes: 1) large gap between lead and welding pad hole.2) poor lead infiltration.3) double panel plugging through hole takes a long time to weld, and the air inside the hole expands.

     

    15. Copper foil up

     

    Appearance characteristics: copper foil from the printed board stripping

    Hazards:  The pcb has been damaged

    Causes: the welding time is too long and the temperature is too high.

     

    16. Peeling

     

    Appearance characteristics: the solder from the copper foil peeling (not copper foil and PCB stripping)

    Hazards:  circuit breaker

    Causes: poor metal coating on the welding pad.