Surface Mount Technology (Surface Mount Technology) is an electronic mount technology that uses professional automatic assembly equipment, such as solder paste printing machine, placement machine, reflow welding, etc. weld surface assembly elements (types include resistors, capacitors, inductors, etc.) to the surface of the circuit board. The computer, mobile phone, printer, MP4, digital image, high-tech control system with strong function are all produced by SMT equipment, which is the core technology of modern electronic manufacturing.

Most electronic products require working and storage under dry conditions. According to statistics, more than 1/4 the world‘s industrial rejected products every year are related to moisture damage. For the electronic industry, the harm of humidity has become one of the main factors of product quality control.

In semiconductor industry,moisture can penetrate through IC plastic package and invade IC interior from the gap such as pin, resulting in IC moisture absorption phenomenon. in SMT heating processs,the moisture entering the inside of the IC is heated and expanded to form water vapor, and the resulting pressure causes the ic resin package to crack, and the metal inside the device is oxidized, which leads to the product failure.

Furthermore, when the components is in the welding process on PCB boards, it will also lead to virtual welding due to the release of water vapor pressure. according to the J-STD-033 standard, SMT components after exposure to high humidity air environment must be placed in an electronic drying cabinet below 10% RH humidity for 10 times the time of exposure to restore the “workshop life” of the components to avoid scrapping and ensure safety.

Dampness caused serious problems to the quality control and reliability of products in electronic industry which must be dried according to IPC-M190 standards.
The chip will be indicated its specific wet sensitive level when it leaves the factory. Another important criterion in the IPC standard is to specify the humidity required to store a chip at its corresponding level.

For chip moisture-proof storage, there are two standards:10% RH below and 5% RH below dry cabinet,which is the common used series in mainstream chips. “Unsealed MSD, may recover the workshop life consumed by this MSD at a time of 5 or 10 times of the specified humidity storage (e.g .10 RH or less) when the exposure time does not exceed 72 hours .” Exposure time is the time when the MSD is placed in a high humidity environment after unsealing.

Humidity has become one of the main factors of product quality control in SMT industry. SMT products storage environment humidity is below 40%, some also require lower humidity. The storage of humidity sensitive materials has been a headache for all EMS manufacturers. After absorbing moisture of electronic components and circuit boards, it is easy to produce virtual welding, which leads to the increase of rejected products. Although it can be improved after baking and dehumidification, the performance of the components is decreased after baking, which directly affects the quality of the products.

NetDry PCB Storage Cabinets can settle all above humidity related problems,welcome to inquiries!