FPC Reflow Soldering
A forced heat convection infrared reflow oven should be used to more evenly change the temperature on the FPC and reduce weld defects. If a single-sided tape is used, since only the four sides of the FPC can be fixed, the middle portion is deformed in a hot air state, the gasket is easily inclined, and molten tin (high-temperature liquid tin) flows to cause void welding, continuous welding, and tin beads to make the process The defect rate is high.
1) Temperature curve test method
Due to the different endothermic properties of the carrier, the types of components on the FPC are also different. The temperature rises during the reflow process and the heat is different. Therefore, please carefully set the temperature curve of the reflow oven. great influence. A safer method is to place two FPC-equipped carrier plates in front of and behind the test board according to the actual board spacing during the production process. At the same time, the components were mounted on the FPC of the test carrier and the temperature was tested with a high temperature wire. The probe is soldered to the test point while the probe leads are secured to the carrier with high temperature tape. Please note that high temperature tape does not cover the test points. Test points should be selected near the solder joints on both sides of the carrier and near the QFP pin. The test results are more reflective of the actual situation.
2) Setting of temperature curve
In the furnace temperature debugging, because the temperature uniformity of the FPC is not good, it is better to use the heating/heating/reflow temperature curve so that the parameters of each temperature zone are easy to control, and the FPC and components are less affected by thermal shock. some. Based on experience, it is best to adjust the furnace temperature to the lower limit of the solder paste technical requirements. The wind speed of the reflow oven usually uses the lowest wind speed that the furnace can use. The reflow oven chain has good stability and no jitter.