Storage of Omni Printed Circuit Boards

    pcb storage

    It is important to understand the core laminate materials used in the manufacturing of PCB boards will absorb available moisture from the environment until an equilibrium is reached. Any moisture which has been absorbed will vapourize during the solder process which may lead to voiding and delamination. The amount of absorption is influenced by the length of time the bare circuit boards have been stored and the storage conditions.

    Recommended PCB Board Storage Conditions

    Between 68°F - 82°F (20°C - 25°C) Relative humidity < 50% 

    Maximum Recommended PCB Board Storage Time

    Between the manufacturing date of the bare PCB board (Omni Circuit Boards applies the date code in the format YYWW to each PCB) and the assembly of the PCBA.

    • Immersion White Tin – 9-12 months
    • Hot Air Solder Leveling (HASL) – 9-12 months
    • ENIG – 1 Year

    Handling

    Once the package is opened, maintain the following conditions:

    • Relative humidity <50%, temperature 20-25 ºC. 
    • Assembly must take place within 1 week and preferably immediately. 
    • Do not expose the PCB boards to a corrosive gas or liquid environment. 
    • Do not expose the PCB boards to direct sun light. 
    • Fingerprints must be avoided (wear gloves).

    Remedies

    If you have purchased your panelized Immersion White Tin PCB boards from Omni Circuit Boards and have had them in stock for more than 9 months you can return them to us for Re-Tinning for a nomninal charge. In addition if you have opened a package of PCBs and require them to be re-sealed return them to us for repackaging, (including fresh desiccant) at no charge.

    Baking Out PCB board’s

    If printed circuit boards have been removed from their sealed packages more than 1 week prior to assembly baking out is recommended to remove any moisture which may have been absorbed. Baking out of HASL, ENIG and Immersion White Tin requires the same process.

    • Heat the PCB board to a temperature between 105 ºC and 115 ºC (above the boiling point of water) for 4-6 hours.

    Although baking out will reduce the solderability of the PCB board this is still preferable to issues which may be encountered with moisture or water outgassing during the assembly process. Higher temperatures than those recommended may also adversely reduce the solderability of the circuit board.

    Packaging Specifications

    • Vacuum sealed
    • ESD shielded moisture barrier bags
    • Thickness 6.0 mil
    • Resistivity of less than 1x1012 ohms/sq
    • Meets the full static decay requirements of MIL-PRF-81705E, Type II and EISA-541.

     

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