16 PCB welding defects! What are their hazards?

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16 PCB welding defects! What are their hazards? [Copy link]

The following is a detailed explanation of common welding defects, appearance characteristics, hazards, and cause analysis.

1. Cold soldering

1. Appearance characteristics

There is an obvious black boundary between the solder and the component leads or the copper foil, and the solder is sunken towards the boundary.

2. Hazards

Not working properly.

3. Cause Analysis

1) The leads of components are not cleaned properly, not tinned properly or are oxidized.

2) The printed circuit board is not cleaned well and the quality of the sprayed flux is poor.

2. Solder Buildup

1. Appearance characteristics

The solder joints are loosely structured, white and dull.

2. Hazards

Insufficient mechanical strength, possible solder joint failure.

3. Cause Analysis

1) The solder quality is poor.

2) The welding temperature is not enough.

3) The leads of components are loose when the solder has not solidified.

3. Too much solder

1. Appearance characteristics

The solder surface is convex.

2. Hazards

Solder is wasted and may hide defects.

3. Cause Analysis

Solder withdrawal too late.

4. Too little solder

1. Appearance characteristics

The soldering area is less than 80% of the pad and the solder does not form a smooth transition surface.

2. Hazards

Insufficient mechanical strength.

3. Cause Analysis

1) Poor solder fluidity or premature solder withdrawal.

2) Insufficient flux.

3) The welding time is too short.

5. Rosin welding

1. Appearance characteristics

There is rosin slag in the weld.

2. Hazards

Insufficient strength, poor conduction, and intermittent connection.

3. Cause Analysis

1) There are too many welding machines or they are out of service.

2) Insufficient welding time and insufficient heating.

3) The surface oxide film has not been removed.

6. Overheating

1. Appearance characteristics

The soldering point is whitish, has no metallic luster, and has a rough surface.

2. Hazards

The pads are prone to peeling and the strength is reduced.

3. Cause Analysis

The soldering iron power is too high and the heating time is too long.

7. Cold welding

1. Appearance characteristics

The surface is in the form of tofu dregs-like particles, which may sometimes have cracks.

2. Hazards

Low strength and poor conductivity.

3. Cause Analysis

The solder shakes before solidifying.

8. Poor infiltration

1. Appearance characteristics

The interface between the solder and the weldment is too large and not smooth.

2. Hazards

The strength is low, not working or intermittent.

3. Cause Analysis

1) The weldment is not cleaned properly.

2) Insufficient flux or poor quality.

3) The weldment is not heated sufficiently.

9. Asymmetry

1. Appearance characteristics

The solder does not fully flow onto the pad.

2. Hazards

Insufficient strength.

3. Cause Analysis

1) The solder fluidity is poor.

2) Insufficient flux or poor quality.

3) Insufficient heating.

10. Looseness

1. Appearance characteristics

The wires or component leads are movable.

2. Hazards

Poor continuity or no continuity.

3. Cause Analysis

1) The lead moves before the solder solidifies, causing gaps.

2) The lead is not processed well (poor wetting or no wetting).

11. Pull tip

1. Appearance characteristics

A tip appears.

2. Hazards

The appearance is not good and it is easy to cause bridging.

3. Cause Analysis

1) Too little flux and too long heating time.

2) The soldering iron is withdrawn at an improper angle.

12. Bridging

1. Appearance characteristics

Adjacent wires are connected.

2. Hazards

Electrical short circuit.

3. Cause Analysis

1) Too much solder.

2) The soldering iron is withdrawn at an improper angle.

Analysis of common defects, hazards and causes of circuit board welding

13. Pinhole

1. Appearance characteristics

Holes can be seen by visual inspection or low-power magnification.

2. Hazards

The strength is insufficient and the solder joints are prone to corrosion.

3. Cause Analysis

The gap between the lead and the pad hole is too large.

14. Bubbles

1. Appearance characteristics

There is a flame-like solder bump at the base of the lead, with a cavity hidden inside.

2. Hazards

It is temporarily conductive, but it is easy to cause poor conduction for a long time.

3. Cause Analysis

1) The gap between the lead and the pad hole is large.

2) Poor lead wetting.

3) The welding time of the double-sided board through-hole is long, and the air in the hole expands.

15. Copper foil warping

1. Appearance characteristics

The copper foil peels off from the printed circuit board.

2. Hazards

The printed circuit board is damaged.

3. Cause Analysis

The welding time is too long and the temperature is too high.

16. Peeling

1. Appearance characteristics

The solder joint is peeling off from the copper foil (not the copper foil and the printed circuit board).

2. Hazards

Circuit breaker.

3. Cause Analysis

Poor metallization on pad.

This content is originally created by EEWORLD forum user Zhong Xinhua . If you want to reprint or use it for commercial purposes, you must obtain the author's consent and indicate the source

qwqwqw2088

The soldering area is less than 80% of the pad and the solder does not form a smooth transition surface.

Too little solder is harmful to the mechanical strength.

Also correct