How does humidity affect electronic products? Importance of components baking to remove oxidation

Date：2022-09-09 15:54:51Views：1519

When the humidity of the storage environment of electronic components is too high, moisture will enter the IC device through the bonding surface of the packaging materials and components, causing oxidation, corrosion and short circuit of the internal circuit, and the high temperature in the assembly and welding process will cause the humid gas entering the IC to expand and generate pressure, causing the plastic to separate from the inside of the chip or lead frame (delamination), wire binding damage, chip damage, internal cracks and cracks extending to the surface of the component, Even components swell and burst, which will lead to assembly repair or even scrapping. More importantly, those invisible and potential defects will be incorporated into the product, causing problems in the reliability of the product. Most other IC electronic components also have the hazard of moisture. It is very important to dry electronic components to remove oxidation. This article has collected and sorted out some materials, hoping to have greater reference value for all readers.

Hazards of humid air to electronic products:

1. Liquid crystal devices: Although the glass substrates, polarizers and filters of liquid crystal devices such as liquid crystal display barriers need to be cleaned and dried in production, they will still be affected by moisture after cooling, reducing the product pass rate. Therefore, it should be stored in a dry environment below 40% RH after drying.

2. Other electronic devices: capacitors, ceramic devices, contact parts, switch parts, solder, PCB, wafer, quartz oscillator, SMT glue, electrode material adhesive, electronic paste, high brightness devices, etc. will be harmed by moisture.

3. The finished electronic whole machine will also be harmed by moisture in the warehouse process. For example, if it is stored in a high environment for too long, it will lead to failure. For computer IC, BGA, PCB, etc., devices waiting for soldering in the tin furnace, devices that have been baked and warmed up, and products that have not yet been packaged, they will all be affected by moisture.

4. Integrated circuit: the harm of humidity to the semiconductor industry is mainly manifested in the fact that humidity can penetrate the IC plastic package and penetrate into the IC from the gaps such as pins, resulting in moisture absorption of IC. Water vapor is formed in the heating process of the SMT process, and the generated pressure causes the IC resin seal to crack, and oxidizes the metal inside the IC device, resulting in product failure. In addition, when the device is soldered on the PCB board, the water vapor pressure will be released, which will also lead to false soldering.

Why should electronic components be baked to remove moisture?Reasons why electronic components must be baked to remove moisture before welding and assembly:

① If the electronic components are not dried after being damp in daily or extended storage, the metal materials inside the components are prone to corrosion due to humidity (the resistance and capacitance values change obviously in about two years, and the circuit break occurs seriously); The sealing protection process measures are not taken in time for the device sealing failure caused by the temperature impact during the mechanical mounting and welding of the equipment. The moisture, sulfur and other substances in the air environment enter the metal inside the device through the sealing crack (damage) and then lead to wet corrosion and silver sulfide corrosion. This phenomenon often gradually shows the data drift or function failure of PCBA components after two or four years. This failure lag phenomenon is very harmful to the whole machine, Losses are often batch wise.

② With the development of electronic devices towards high integration and miniaturization, the lines are increasingly dense. In the manufacturing process of the electronic industry, wetted devices will cause short circuit due to solder spatter during heating and welding. It is required to dehumidify and dry the devices before welding (manual, re welding and wave soldering). In particular, BGA, QFP and other hidden solder joints or closely spaced devices will be scrapped because they cannot be repaired

③ The electronic components shall be dried safely according to the standards and process requirements before and after the post welding cleaning and three prevention coating.

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