Drying and Dry-Packing
Drying of components
Precaution must be taken for integrated circuit plastic packages because of their moisture sensitivity. Depending on the way of processing, the potential vapour pressure build-up inside the component during soldering may lead to micro-cracks or device bursting (popcorn-effect). As a matter of fact, the smaller the devices, the bigger the problem! However, in order to avoid moisture induced damages it is absolutely necessary to make sure that the integrated circuits are "dry" when being further processed. For this reason, the goods will generally be delivered in a "Dry-Pack".
Dry-Packing
The "Dry-Pack" bags are made of a solid aluminium foil middle layer and an inner antistatic polyethylene layer providing moisture vapour protection. Therefore, no moisture will affect the dried devices. Still, a new device drying will become indispensable if the pouches are defective or the permitted opening time period has been exceeded. This special service is offered by HTV. The devices are dried under high temperature and low humidity, packaged afterwards in a Dry Pack containing a humidity-indicator-strip as well as a desiccant absorbing any moisture, and are finally vacuum sealed.
MSD-Level-Tracking
The manufacturers define a so-called MSD-Level (Moisture-Sensitive-Device) for their products, as a measure for the permitted opening time of a Dry-Pack which can vary from a few hours until an unlimited period of time. A high MSD-Level (e.g. 5 or 6) is always considered as a logistical challenge for processing. By hermetically sealing the components between each individual production step, HTV keeps the opening time as short as possible. The phases during which the packages had been opened are recorded, deducted from the allowed opening time, and the bags are
marked accordingly.
Long time nitrogen flush packaging
A special Dry-Pack method is applied for long time device storing (e.g. for spare parts). After additive padding, the dried devices are packaged in extremely tough and durable bags. The bag is flushed with nitrogen and vacuum sealed thereafter to prevent any component corrosion through oxidation-enhancing oxygen molecules.
