In the actual production process of printed circuit boards (PCBs), we often encounter the phenomenon of solder beads coming out of via holes. If it fails to cope, it may affect the performance and reliability of electronic equipment. In this article, we will discuss the phenomenon of solder beads and what effects it may cause, and the reason for this phenomenon and its solution as well.
What is the solder beads phenomenon?
Via holes is a key component when manufacturing printed circuit boards. They are used to establish electrical connections between multilayer PCB. Sometimes these holes need to be filled with solder to ensure a reliable connection.
Solder beads are a kind of solder balls created during the components are soldered on the print circuit boards. When the solder paste is overused, the solder beading occurs.
What causes the phenomenon of solder beads in via holes?
There may be several reasons for this phenomenon.
1 Improper use of flux
The main function of flux is to remove the oxide layer, improve the wettability of tin and reduce the surface tension of the soldering interface. Excessive or uneven flux can lead to solder beads.
2 Inappropriate thermal profile settings
Excessively high temperatures in the preheating area may prematurely deactivate the flux active species, while excessively high temperatures in the peak area may cause excessive melting of the tin passing through the hole, resulting in solder beads.
3 PCB design issues
In PCB design, if the PCB vias hole size is too large or the solder paste is not completely filled, it may cause tin to flow out of the hole during heating. In addition, too small pad size and improper pad spacing may also cause solder beading.
What are the effects caused by the phenomenon of solder beads coming out of via holes?
The phenomenon of solder beads through via holes may cause the following problems:
1. Electrical performance issues
When solder beads form and contact adjacent circuit components, it might cause short circuits or other unstable electrical performance.
2. Compromised PCB signal integrity
Solder beading may bring undesired parasitic capacitance, inductance, or resistance in the signal path, resulting in degraded signal transmission. This can lead to problems such as signal distortion, crosstalk, etc., which greatly affect the performance of electronic equipment.
3.Difficulty in process control
The phenomenon of solder beads through holes may lead to an unstable process, thereby increasing scrap rate and production cost. In order to ensure product quality, more time and resources need to be invested in adjusting and controlling process parameters.
4.Heat dissipation issues
Excessive solder beads may affect the heat dissipation performance of the PCB. Since the thermal conductivity of solder is generally lower than that of the PCB substrate, the presence of solder beads can cause localized hot spots that can affect component life and performance.
How to cope with the solder beads coming out of via hole on the PCB?
In view of the phenomenon of solder beads coming out of via holes, the following optimizations can be considered:
1. Adjust thermal profile parameters
Reasonably set the preheat temperature, peak temperature and cooling zone temperature to ensure that tin melting and fluidity are in the appropriate range. In addition, the temperature change of the thermal profile should be as gentle as possible to reduce the thermal stress during the tin melting process.
2. Improve PCB design
Through optimizing design parameters such as hole size, pad size and spacing to reduce the occurrence of solder beads. The size of the through hole should be reasonably designed according to the actual application requirements while considering the allowable range of the process. Pad size and spacing also need to be optimized according to the characteristics of electronic components to ensure soldering quality and avoid solder beads.
3. Optimize the use of flux
It is critical to select the appropriate flux, as different types of flux are suitable for different process conditions and soldering requirements. Ensure that the flux is applied evenly and in a moderate amount to avoid solder beads. In addition, regularly checking the quality of the flux to ensure its stable performance is also an important measure to reduce the occurrence of solder beads.
4.Strictly control the production process
During the production process, related regulations and operating specifications should be strictly implemented, and the monitoring of welding parameters, equipment and solder should be strengthened. Carry out regular maintenance of the equipment to ensure the stable operation of the equipment. In addition, strengthen the training of operators to improve their sensitivity and problem-solving ability to handle problems that may arise during wave soldering.
During PCB manufacturing, there are many factors that result in solder beads. It is far from enough to focus on a certain aspect or adjust a certain parameter. So, we need to carefully control every detail in the preparation stage before production and during the production process, and pay attention to how to control various factors that affect solder beads, so as to achieve the best soldering effect and meet the high-quality requirements of electronic manufacturing technology.
Solder beads are a phenomenon caused by excessive solder paste deposit, which can result in short circuits. It often occurs at the side of chip components such as resistors and capacitors.
- Improper use of flux
- Inappropriate thermal profile settings
- Poor PCB design
- Electrical performance issues
- Compromised PCB signal integrity
- Difficulty in process control
- Heat dissipation issues