- Short circuit
The phenomenon of forming a joint between two independent adjacent solder joints after soldering, which is caused by the distance between the solder joints being too close, improper arrangement and design of the parts, incorrect soldering direction, too fast soldering speed, insufficient flux application and poor soldering properties of the parts, poor solder paste application, and excessive solder paste.
- Empty welding
The reason for this situation is that the solder groove is not coated with tin, and the parts and substrate are not welded together. The reasons for this situation include unclean solder grooves, raised feet, poor soldering properties of the parts, excessive positioning of the parts, improper glue dispensing operations, and overflow of glue on the solder groove, all of which can cause empty soldering. The PAD of air welded parts is mostly in a shiny and smooth shape
- Fake welding
There is tin between the part foot and the welding groove, but it is not completely caught by the tin. Most likely due to the presence of rosin in the solder joints or other factors.
- Cold welding
Also known as undissolved tin, it is caused by insufficient soldering temperature or short soldering time. This disadvantage can be improved by secondary soldering. The solder paste surface of the cold solder joint is dark and mostly in powder form.
- Parts detachment
After the soldering operation, the parts are not in their proper position due to improper selection or dispensing of adhesive materials, incomplete curing of adhesive materials, high soldering waves, and slow soldering speed.
- Missing parts
The parts that should have been installed were not installed.
- Damage
There are obvious defects in the appearance of the parts, material defects, process collisions, or cracking of the parts during the soldering process. Insufficient preheating of parts and substrates, as well as rapid cooling after soldering, all have a tendency to promote the cracking of parts.
- Erosion and erosion
This phenomenon often occurs on passive parts due to poor coating treatment at the endpoints of the parts. Therefore, when passing through the tin wave, the coating dissolves into the tin bath, causing damage to the structure of the endpoints and poor solder adhesion. Higher temperatures and longer soldering times will make the corrosion of defective parts more severe. In addition, the temperature of general flow soldering is lower than that of wave soldering, but the time is longer. Therefore, if the part is not good, it often causes erosion. In addition to changing the part, controlling the flow soldering temperature and time appropriately, silver containing solder paste can also be selected to suppress the dissolution of the part endpoint. This is much more convenient for operation than changing the solder composition of wave soldering.
- Tin tip
The surface of the solder joint does not present a smooth continuous surface, but has sharp protrusions, which may be caused by excessive soldering speed, insufficient flux application, etc.
- Less tin
The soldering part or part foot has insufficient tin content.
- Tin ball (bead)
Tin quantity spherical, on PCB, parts, or part feet. Poor quality or prolonged storage of solder paste, unclean PCB, improper preheating, improper solder paste coating operation, and prolonged operation time of solder paste coating, preheating, and flow soldering steps can all easily cause solder balls (beads).
- Circuit breaker
The line should be connected but not conducting.
- Tombstone Effect
This phenomenon is also one of the types of open circuits, which is prone to occur on CHIP parts. The reason for this is that during the soldering process, different tensile forces are generated between different solder joints of the parts, causing one end of the part to lift up. The difference in tensile forces between the two ends is related to the amount of solder paste, soldering properties, and the difference in soldering time.
- Wick effect
This often occurs on PLCC parts, and the reason for its formation is that the temperature of the part feet rises relatively high and quickly during flow welding, or the solder adhesion of the solder groove is poor, which causes the solder paste to melt and rise along the part feet, resulting in insufficient solder joints. In addition, insufficient or no preheating, as well as easy flow of solder paste, can all contribute to this phenomenon.
- CHIP Parts Whitening
In the SMT process, the marking surface of the part value is reversed and soldered onto the PCB, making it impossible to see the part value. However, if the part value is correct, it will not affect its functionality.
- Polarity reversal/direction reversal
The component is not placed in the specified direction
Displacement
Excessive or insufficient dispensing
Standing sideways