4 WLCSP Handling During Packaging, Shipping, and Surface Mount Technology (SMT)

The following information details handling procedures that must be used with a WLCSP product packed in a Moisture Barrier Bag (MBB) and intended for surface mount applications. Following these handling guidelines will ensure that components maintain their as-shipped dry state, alleviating package cracking and other moisture-related stress-induced concerns that may be associated with the surface mount process. Manual handling of parts with tweezers must be avoided due to the risk of chip out (cracks in the silicon).

  1. Incoming Inspection:

    Upon receipt, shipments should be inspected for bag integrity. There should not be holes, gouges, tears, or punctures of any kind that expose either the contents or the inner layer of the bag.

  2. Storage Conditions/Shelf Life:

    When MSL-1 devices are stored according to the JEDEC specification J-STD-033, it has unlimited. shelf life.

  3. Opening an MBB:

    To open an MBB, cut across the top of the bag, care should be taken not to damage enclosed materials. Once the bag has been opened, follow the guidelines for ambient exposure time in the following section to ensure that devices are maintained below the critical moisture level.

  4. Manufacturing Conditions/Floor Life:

    Microchip classifies surface mount components into levels of moisture sensitivity, the labels on the MBB list the moisture sensitivity level and the allowable floor life. Microchip recommends that once the MBB is opened, components from the bag be surface mounted and reflowed within the time indicated on the MBB label. This time is based on a manufacturing environment, that is not more extreme than 30ºC/60% RH and a maximum component body temperature during solder reflow of 260ºC. If the component cannot be mounted within this time frame, they should be put into a storage environment immediately, as specified in J-STD-033, or sealed into an MBB as soon as possible.

  5. Resealing an MBB:

    If users need to reseal the MBB for any reason, Microchip recommends the following guidelines to ensure that the bag seal does not allow moisture into the bag. The seal area must not exhibit any separation when subjected to the load and temperature conditions specified in the JEDEC J-STD-033 specification. The integrity of the seal is vital to the storage life of the devices.