In the world of electronics assembly, moisture can be a very dangerous threat. Components, and particularly those in plastic capsules, can absorb moisture from the atmosphere if they are not packaged correctly. When components undergo standard soldering processes, they go from room temperature to being exposed to a very high level of heat within a short space of time. As a result, these drops of sealed moisture turn into steam and cause an internal explosion. This is known as the “popcorn effect”. It can cause the plastic capsule to break or become deformed.
At best, the fault presents itself immediately and the circuits fail the testing stage before they are supplied to our customers. But in the worst case scenario, the faults remain dormant and the components pass the testing phase only to fail a few days later, when there might already be a large quantity on the market and the problem could be extremely widespread.
That’s why IKOR Group uses preventive controls and good practices to minimise any risk for our customers. Temperature and moisture are controlled within their maximum safe levels, which is 30ºC and 60% respectively in this case.
Sensitive components are vacuum sealed in safe conditions and packaged with dessicants and moisture indicator cards. Once the packaging is open, we have strict controls in place to ensure that components are never left exposed for longer than the acceptable time limit. Components are vacuum packed once again after they have been used. The most sensitive components are stored in special chambers where we can control moisture and keep it at a low level.
In the event that the component has been exposed for longer than the maximum permissible time, they are baked (dried) to remove that moisture in a safe and controlled manner.
We know the maximum exposure time thanks to a rating system called the Moisture Sensitivity Level (MSL), which appears as a sticker on rolls of sensitive components. The higher the number, the less time the packaging can remain open as the component will absorb moisture at a faster rate.
This rating is regulated by IPC standards and can range from 1 to 6. For example, a component rated as MSL 2 can last for a year, but an MSL 3 may only remain unsealed for a week. It is now very common to find components rated at Level 3 or above due to the higher soldering temperatures specified in RoHS regulations, as well as the rise in the use of sensitive components such as BGAs.