1. Bubbles.
During SMT processing and soldering, the leads of the components are inserted into the holes of the printed circuit board. After soldering, a solder arch with a small hole at its root may form, potentially concealing significant voids underneath. This defect is known as bubbles. The voids occur because the copper foil of the printed circuit board has a high heat capacity. Although soldering is complete, the board’s backside hasn’t cooled yet, causing the temperature to rise due to thermal inertia. This results in the solder joint’s exterior condensing while internal gas escapes, forming voids. Additionally, contaminants on the pads, poor oxidation of component leads, oversized vias, thin leads, insufficient solder, and excess rosin can also contribute to this issue.
2. Lack of solder.
When soldering with an electric soldering iron, insufficient solder can lead to poor wetting and prevent the solder from forming a smooth, flat pad shape. This defect is known as lack of solder. Possible causes include premature removal of the solder wire, a small contact area between the soldering iron and the solder, excessive temperature, or prolonged soldering time. This defect impairs circuit conduction due to environmental degradation and weakens mechanical strength between solder joints. Adding solder wire can remedy this issue from the outset.
3. Overheating.
The drawbacks of overheating in soldering include white solder joints lacking metallic luster and a rough appearance. The primary causes of overheating are excessive power of the soldering iron, an excessively high temperature at the soldering iron tip, and prolonged heating time. Overheating can cause pads to easily lift off, which reduces the mechanical strength of the solder joints.
4. Cold welding.
During SMT processing and soldering, if the solder does not fully solidify and the wires or leads of the components shift, the solder joints may appear dull and uneven, with a loose structure and microcracks. This defect is known as cold welding. Cold welding typically results from removing the PCB too early, movement of the soldered component, or inadequate soldering iron power. The primary issues with cold welding are reduced joint strength and poor conductivity. To prevent cold welding, ensure that the wires or leads of the components remain stable during soldering. If necessary, re-soldering can be done with additional flux.
5. Copper foil lifting, peeling, and pad detachment.
When the copper foil is lifted or peeled from the printed circuit board, or if the pad detaches completely, it is referred to as copper foil lifting and peeling. This issue often arises from improper soldering techniques, overheating, or using the soldering iron tip to pry the solder. The consequences of copper foil lifting include potential short circuits. To address this issue, practice proper drilling techniques, repeat as necessary, and master the soldering process.
6. Pinhole formation.
After soldering, if visual inspection or use of a low-power magnifying glass reveals a hole in the solder joint, it is referred to as a pinhole. The primary cause of pinholes is a large gap between the PCB pad hole and the component lead. Pinholes can weaken the joint strength and increase susceptibility to corrosion. To mitigate pinholes, ensure that the pad hole size on the PCB is appropriately sized and not excessively large.
7. Rosin soldering.
Rosin soldering occurs when a flux film and dissolved oxides or contaminants form a solder joint resembling tofu slag. This defect arises when the soldering iron tip is removed too soon, preventing the flux from properly floating to the surface. The effects of rosin soldering include reduced joint strength and poor circuit conductivity, often resulting in intermittent connections. To prevent rosin soldering, avoid using excessive flux and maintain proper soldering techniques at all times.
During SMT processing and soldering, the leads of the components are inserted into the holes of the printed circuit board. After soldering, a solder arch with a small hole at its root may form, potentially concealing significant voids underneath. This defect is known as bubbles. The voids occur because the copper foil of the printed circuit board has a high heat capacity. Although soldering is complete, the board’s backside hasn’t cooled yet, causing the temperature to rise due to thermal inertia. This results in the solder joint’s exterior condensing while internal gas escapes, forming voids. Additionally, contaminants on the pads, poor oxidation of component leads, oversized vias, thin leads, insufficient solder, and excess rosin can also contribute to this issue.
2. Lack of solder.
When soldering with an electric soldering iron, insufficient solder can lead to poor wetting and prevent the solder from forming a smooth, flat pad shape. This defect is known as lack of solder. Possible causes include premature removal of the solder wire, a small contact area between the soldering iron and the solder, excessive temperature, or prolonged soldering time. This defect impairs circuit conduction due to environmental degradation and weakens mechanical strength between solder joints. Adding solder wire can remedy this issue from the outset.
3. Overheating.
The drawbacks of overheating in soldering include white solder joints lacking metallic luster and a rough appearance. The primary causes of overheating are excessive power of the soldering iron, an excessively high temperature at the soldering iron tip, and prolonged heating time. Overheating can cause pads to easily lift off, which reduces the mechanical strength of the solder joints.
4. Cold welding.
During SMT processing and soldering, if the solder does not fully solidify and the wires or leads of the components shift, the solder joints may appear dull and uneven, with a loose structure and microcracks. This defect is known as cold welding. Cold welding typically results from removing the PCB too early, movement of the soldered component, or inadequate soldering iron power. The primary issues with cold welding are reduced joint strength and poor conductivity. To prevent cold welding, ensure that the wires or leads of the components remain stable during soldering. If necessary, re-soldering can be done with additional flux.
5. Copper foil lifting, peeling, and pad detachment.
When the copper foil is lifted or peeled from the printed circuit board, or if the pad detaches completely, it is referred to as copper foil lifting and peeling. This issue often arises from improper soldering techniques, overheating, or using the soldering iron tip to pry the solder. The consequences of copper foil lifting include potential short circuits. To address this issue, practice proper drilling techniques, repeat as necessary, and master the soldering process.
6. Pinhole formation.
After soldering, if visual inspection or use of a low-power magnifying glass reveals a hole in the solder joint, it is referred to as a pinhole. The primary cause of pinholes is a large gap between the PCB pad hole and the component lead. Pinholes can weaken the joint strength and increase susceptibility to corrosion. To mitigate pinholes, ensure that the pad hole size on the PCB is appropriately sized and not excessively large.
7. Rosin soldering.
Rosin soldering occurs when a flux film and dissolved oxides or contaminants form a solder joint resembling tofu slag. This defect arises when the soldering iron tip is removed too soon, preventing the flux from properly floating to the surface. The effects of rosin soldering include reduced joint strength and poor circuit conductivity, often resulting in intermittent connections. To prevent rosin soldering, avoid using excessive flux and maintain proper soldering techniques at all times.
