Introduction
Wave soldering is a traditional soldering method for multi-layer and large size electronic components. Wave soldering machine uses molten tin to wet the contact surface, and then utilizes the action of a mechanical wave to dip the solder into the solder joint to complete the soldering. The advantages are simplicity of operation, relatively inexpensive equipment, and suitability for small-scale production and maintenance work.
So, what is wave soldering solder bridging? Why do you need to pay attention to? In this article, we will analyze the reasons for solder bridging, provide solutions and preventive measures.
I. What is solder bridging phenomenon?
Wave soldering welding that is adjacent to the two solder joints connected together, specifically the solder in the adjacent different wires or components to form a non-normal connection between the phenomenon, with the component pin spacing becomes smaller and PCB line density increases, the chances of this defect gradually increase. In the wave soldering, wave soldering often produced in the SMD components facing the incorrect direction, incorrect pad design, the distance between the components is not far enough will also produce continuous welding.
II. What are the reasons for wave soldering solder bridging?
1. PCB soldering surface does not take into account the emission of brazing material flow, line distribution is too dense, the pins are too close or irregular.
2. PCB pad is too large or component pins too long (generally 008 ~ 3mm), welding caused by too much tin.
3. PCB immersed in the brazing material is too deep, welding caused by the board surface too much tin.
4. PCB surface or component pins with residue.
5. PCB surface inserted component pins irregular or skewed insertion, welding before the pins have been close to each other or have been in contact.
6. Poor solderability or preheating temperature or flux activity is not enough.
7. The soldering temperature is too low or the conveyor speed is too fast, the heat absorption of the solder joint is insufficient. In SnCu brazing material, due to poor fluidity, more sensitive to temperature, this phenomenon is very obvious.
8. Brazing material is contaminated, such as Fe (iron) contamination formed by contaminants or brazing material oxides can cause continuous soldering phenomenon.
Note: a certain match with the pad and pin solder joints under certain conditions can carry a certain amount of solder paste, if not handled properly, the excess may cause wave soldering phenomenon.
III. How to solve the wave soldering problem?
1. Flux material optimization
Composition is not appropriate, resulting in insufficient flux activity or spray flux spray volume is too small.
It is recommended to replace the high activity flux or increase the amount of spray.
2. Process optimization
Pre-heating, tin furnace temperature setting is not appropriate, the speed of transportation is too fast, resulting in continuous soldering phenomenon.
It is recommended to optimize the preheating temperature and solder temperature curve.
Adjust the height and transport speed of wave soldering.
3. PCB design improvement
PCB pads are not enough solder drag bit.
It is recommended to increase the isolation area between the pads and optimize the layout of components.
IV. What are the wave soldering solder bridging preventive measures?
1. Develop SOP
The establishment of a complete set of standardized procedures for wave soldering machine operations is the first step in the prevention of welding defects. Including:
- Clearly defined solder temperature, transfer speed, preheating temperature and other key parameters of the setting range.
- Standardize the amount of flux spray and spray method.
- Standardize component insertion direction and PCB placement angle.
- Define the list of items to be checked before equipment startup (e.g. solder bath cleanliness, wave height, etc.)
2. Establish regular inspection and feedback mechanism
Continuous quality monitoring is the key to preventing problems. The following measures are recommended:
- Sample test solder joint quality after each batch of production and record the defective rate.
- Use tools such as pyrometer and dross analyzer to monitor solder status.
- Compare historical data and make timely adjustments when trend abnormalities are detected.
3. Strengthen staff training and awareness-raising
- Regularly organize training courses on wave soldering principles, common fault identification and handling.
- Encourage employees to put forward suggestions for improvement, forming a quality management atmosphere for all staff.
- Repeated problems are reviewed and explained to prevent recurrence.
4. Use AOI machine to assist in monitoring.
AOI machine is introduced to improve inspection efficiency and accuracy. Its advantages in preventing continuous soldering include:
- Quickly identifying typical defects such as bridging, short circuits, and false soldering.
- Provides traceable quality data for trend analysis.
- Supports interfacing with MES systems to realize automated quality control.
- Reduces manual inspection errors and improves overall yield rate.
Summarize
As an indispensable part of electronic manufacturing, wave soldering has a direct impact on the stability and reliability of products. As a common welding defect, continuous welding may lead to circuit short-circuiting, functional failure, and may significantly increase rework costs, affecting the overall production efficiency.
We hope that each reader can according to their own production line characteristics, flexible adjustment of process parameters and management processes, continuous optimization of the welding process. Combine theoretical knowledge with practical operation to truly realize high-quality, high-efficiency wave soldering production.
Company profile
Zhejiang NeoDen Technology Co., LTD., founded in 2010, is a professional manufacturer specialized in SMT pick and place machine, reflow oven, stencil printing machine, SMT production line and other SMT Products. We have our own R & D team and own factory, taking advantage of our own rich experienced R&D, well trained production, won great reputation from the world wide customers.
We believe that great people and partners make NeoDen a great company and that our commitment to Innovation, Diversity and Sustainability ensures that SMT automation is accessible to every hobbyist on everywhere.
Post time: May-27-2025