【 JJY 】 Causes and Preventive Methods of the Phenomenon of monument erection in SMT Solder paste processing

inSMTOccasionally, during solder paste processing, there may be"Erect a monument"(That is, the Manhattan phenomenon)The phenomenon occurs, and this situation often happens inCHIPComponent(Such as surface mount capacitors and surface mount resistors)During the reflow soldering process, the root cause is that when the solder paste on the pads at both ends of the component melts during reflow, the wetting force on both sides of the component is unbalanced, which leads to the occurrence of the stele phenomenon. Now, Shenzhen JJY Solder Paste Manufacturer will explain it to you:

SMTThe specific reasons for the occurrence of the stele erection phenomenon in solder paste processing:

1Component issues: There is a significant difference in the shape and size of the welded ends;The weldability of the welded ends varies greatly;The component is too light in weight.

2Substrate material and thickness: The thermal conductivity of the substrate material is poor;The thickness uniformity of the substrate is poor.

3The shape and solderability of the pads: The heat capacity of the pads varies greatly;The solderability of the pads varies greatly.

4Preheating temperature: During the preheating stage of the reflux furnace, if the temperature in the holding zone is set low and the time is short, the probability of the two ends of the components melting simultaneously increases.

5Uneven heating: The temperature distribution inside the reflux furnace is uneven;The temperature distribution on the board surface is uneven.

6Solder paste: The uniformity or activity of the flux in the solder paste is poor;The thickness of the solder paste on the two pads varies greatly;The solder paste is too thick, resulting in poor printing accuracy and severe misalignment.

7When component mounting is offset, the solder paste end that has more contact with the component receives a greater amount of hot melt, melting first and thus pulling up the other end to form an upright position.

Methods for preventing the occurrence of monument erection:

1The solder pads and component surfaces are free from oxidation.

2Select the appropriate substrate material to ensure quality.

3Correctly design and layout the pads. The pad designs should be consistent and there should be no vias on the pads.

4Correctly set the process parameters during the preheating period and adjust the appropriate temperature curve of the furnace temperature according to each different product.

5Appropriately increase the temperature of the holding zone during the preheating stage and extend the time to the upper limit to ensure that the tin at both ends can be fully melted simultaneously.

6Select solder paste with higher activity and improve the printing parameters of the solder paste, especially the window size of the template.

7Adjust the placement accuracy of the components properly to avoid significant placement deviations. During the placement process, try to ensure that the placement accuracy is as high as possible90%That's all.

SMTSolder pasteThe defect of the monument erection process during processing is a major defect in the electronic assembly process, which has a significant impact on the processing quality, straight-through rate and rework cost of the product. Therefore, it is necessary to understand the causes and preventive methods of the monument erection phenomenon, and make timely improvements and solutions to avoid such welding defects.

As a sixteen-year-old veteran solder paste manufacturer, JJY has been committed to the research and development, production and sales of solder paste. The quality of its solder paste is stable, without solder disconnection, false soldering or monument erection. Residual Wuxi beads, bright and full solder joints, firm welding, and excellent electrical conductivity. If you have any needs, please feel free to contact us.