For China pcb manufacturer, storage of surface-mounted components

For China pcb manufacturer, surface mount components are typically in ceramic, metal, and plastic packages. The previous two packages have better air tightness, no sealing problems, and the components can be stored for a long time. However, due to the poor airtightness of the plastic packaging of SMD products, special attention should be paid to the assembled components on the plastic surface.

Most of the IC components used in electronic products are packaged in molded plastic, because mass production is easy to reduce costs. However, due to the certain hygroscopicity of plastic products, plastic components (SOJ, PLCC, QFP) are moisture sensitive components. Since the usual reflow or wave soldering is instantaneously heating the entire SMD, the high heat generated during the soldering process is applied to the plastic SMD casing that has been absorbed humidity, and the thermal stress generated causes cracks in the joint between the molded casing and the pin. Cracks can cause the shell to leak and become wet and slowly fail, and can also loosen the pins and cause early failure.

1,Plastic packaging surface assembly components storage

During storage and usage of plastic package surface assembly components should pay attention to: the warehouse room temperature is lower than 40 ° C, the relative humidity is less than 60%, which is the environmental requirement of the plastic package surface assembly component storage site; the plastic package SMD is packaged In a damp bag with a desiccant when export the factory, and indicate that it is effective for one year, if not use, do not open it.

2, The use of plastic packaging surface assembly device

For China pcb manufacturer, when opening the package, first observe the humidity indicator card included in the package. When all black circles are blue, it means that all SMDs are dry and can be used with confidence; when 10% and 20% of the circles turn pink, it is safe; when 30% of the circles turn pink That means the SMD is in danger of moisture absorption and indicates that the desiccant has deteriorated; when all the circles turn pink, it means that all the SMDs are heavily hygroscopic, and all the SMDs in the bag must be carried out Dehumidification drying treatment before mounting.

The temperature indication card reading method is described as below.For China pcb manufacturer, there are many varieties of temperature indicator cards, but they can basically be classified into six-ring and three-ring. The six-ring temperature indicator card is shown in the figure. The six-circle temperature indicator card can display 10%, 20%, 30%, 40%, 50%, and 60%, and the three-ring temperature indicator card is only 30%, 40%, and 50%. The relative humidity is the percentage of the lilac circle between the pink circle and the blue circle. For example, 30% of the circles turn pink, 40% of the circles are still blue, and the "30%" next to the lilac circle between blue and pink is the relative humidity value.