1. Components may fall off during double-sided SMD soldering on PCBA
PCBA double-sided soldering is increasingly common in the SMT surface mount process. Typically, users first print, mount components, and solder on one side before processing the other side. During this process, component detachment is not a frequent issue. However, some customers opt to skip the initial side soldering to save on process and costs, choosing instead to simultaneously solder both sides. This approach can lead to components falling off during soldering due to inadequate vertical solder adhesion to the component after the solder paste melts. The primary reasons include:
1. Components on the PCB are excessively heavy.
2. Poor solderability of the PCB component’s solder pads.
3. Inadequate wettability and solderability of the PCB solder paste.
We typically address the above issues in sequential order, starting with improvements to the second and third reasons. If these improvements fail to resolve the problem, we recommend securing the components with red glue prior to reflow and wave soldering. This measure effectively resolves the issue in most cases.
Second, tin beads often appear on the PCB surface after soldering. This issue is quite common during the SMT welding process, particularly when users begin using products from new suppliers or encounter instability in their production processes. Customers usually bring this problem to our attention for resolution. Through extensive experimentation, we have identified several potential causes for tin bead formation:
1. Inadequate preheating of the PCB during reflow soldering.
2. Poorly optimized temperature profile in the reflow soldering process, leading to significant temperature differentials between the board’s surface and the soldering area.
3. Failure to allow solder paste to return to room temperature after removal from cold storage.
4. Prolonged exposure of solder paste to ambient air after opening.
5. Splashing of tin powder onto the PCB surface during component placement.
6. Contamination from oil or moisture during PCB printing or transportation.
7. Improper formulation of flux within the solder paste, including non-volatile solvents, liquid additives, or activators.
These points, alongside the second cause, elucidate why issues like excessive tin beads may arise with newly introduced solder paste. The primary concern often lies in the mismatch between the current temperature profile and the solder paste used. When changing PCB suppliers, it is crucial for customers to consult with the solder paste supplier regarding the suitable temperature profile that aligns with the solder paste’s requirements. Issues related to the third, fourth, and sixth causes typically stem from user error, while problems associated with the fifth cause can be attributed to improper storage or expired shelf life of the solder paste, resulting in reduced stickiness or viscosity and subsequent tin powder splashing during SMT placement. The seventh cause pertains to the solder paste production technology employed by the PCB supplier itself.
PCBA double-sided soldering is increasingly common in the SMT surface mount process. Typically, users first print, mount components, and solder on one side before processing the other side. During this process, component detachment is not a frequent issue. However, some customers opt to skip the initial side soldering to save on process and costs, choosing instead to simultaneously solder both sides. This approach can lead to components falling off during soldering due to inadequate vertical solder adhesion to the component after the solder paste melts. The primary reasons include:
1. Components on the PCB are excessively heavy.
2. Poor solderability of the PCB component’s solder pads.
3. Inadequate wettability and solderability of the PCB solder paste.
We typically address the above issues in sequential order, starting with improvements to the second and third reasons. If these improvements fail to resolve the problem, we recommend securing the components with red glue prior to reflow and wave soldering. This measure effectively resolves the issue in most cases.
Second, tin beads often appear on the PCB surface after soldering. This issue is quite common during the SMT welding process, particularly when users begin using products from new suppliers or encounter instability in their production processes. Customers usually bring this problem to our attention for resolution. Through extensive experimentation, we have identified several potential causes for tin bead formation:
1. Inadequate preheating of the PCB during reflow soldering.
2. Poorly optimized temperature profile in the reflow soldering process, leading to significant temperature differentials between the board’s surface and the soldering area.
3. Failure to allow solder paste to return to room temperature after removal from cold storage.
4. Prolonged exposure of solder paste to ambient air after opening.
5. Splashing of tin powder onto the PCB surface during component placement.
6. Contamination from oil or moisture during PCB printing or transportation.
7. Improper formulation of flux within the solder paste, including non-volatile solvents, liquid additives, or activators.
These points, alongside the second cause, elucidate why issues like excessive tin beads may arise with newly introduced solder paste. The primary concern often lies in the mismatch between the current temperature profile and the solder paste used. When changing PCB suppliers, it is crucial for customers to consult with the solder paste supplier regarding the suitable temperature profile that aligns with the solder paste’s requirements. Issues related to the third, fourth, and sixth causes typically stem from user error, while problems associated with the fifth cause can be attributed to improper storage or expired shelf life of the solder paste, resulting in reduced stickiness or viscosity and subsequent tin powder splashing during SMT placement. The seventh cause pertains to the solder paste production technology employed by the PCB supplier itself.
