Moisture Barrier Bags for Vacuum-Packed Wafer Carriers
A moisture barrier bag (MBB) is the outer envelope around a closed wafer carrier. The carrier goes into the bag with desiccant, the air is drawn out and the open end is heat-sealed, which limits moisture reaching the pack during shipping and storage. ePAK sizes each bag to a specific canister, jar, shipper or box.
The standard ePAK moisture barrier bag is a metalized PET+PET+CPE laminate (eM-41) with a static-dissipative surface of 10⁶–10¹¹ Ω/sq. The bag for the 300mm eLX canister with 44mm internal height uses a PET+aluminum foil+CPE laminate (eM-116), and the bag for 3-inch process boats a polyester+aluminum+nylon+PE laminate (eM-227), both with the same surface range. Most sizes use 0.08mm film. Several sizes use 0.14mm film, and the bag for 3-inch process boats uses 0.17mm.
Each bag has a 10mm seal along both long sides and an open end that is heat-sealed after the carrier and desiccant are inside. A yellow warning label with the ESD susceptibility symbol is printed at the center of the front panel: “Attention: bag contains moisture and electrostatic sensitive devices. Do not open or handle except at an approved static safe workstation and under approved humidity control handling procedures.” Bags are specified free of contamination and dust, with sealed edges free of deformation, breaks and incomplete seams.
Bag sizes follow the carrier, not the wafer. A closed 150 or 200mm eLX canister with the 225 x 225mm outline takes a 330 x 380mm bag. 150mm wafer jars and the 150mm Universal canister with 26mm internal height take a 230 x 280mm bag. 300mm flex frame canisters take a 692 x 720mm bag. The compatibility list below gives the bag for each ePAK product family.
Silica gel desiccant in Tyvek® pouches of 5, 15 and 35g goes inside the bag with the carrier to absorb residual moisture in the pack.
