IPC/JEDEC J-STD-033D - 3.3.2.2.1 Desiccant Quantity Calculation

Hello Everyone In Board World, Looking for some discussion on calculating how long moisture sentive boards can be stored on shelves with forum in 3.3.2.2.1 Desiccant Quantity Calculation

When the desiccant capacity at 10% RH and 25 °C is known, the following equation should be used:

U = (0.304 * M * WVTR * A) / D Where: U = Amount of desiccant in UNITS 0.304 = Average number of days per month/100 in2 (30.4/100)

M = Shelf life desired in months (see 3.3.6 for shelf life) WVTR = Water vapor transmission rate in grams/m2 [grams/100 in 24 hrs

A = Total exposed surface area of the MBB in square decimeters (square inches)

D = The amount of water in grams, that a UNIT of desiccant will absorb at 10% RH and 25 °C

Wanted to find a few engineers who have executed this formula with desiccant beads allowed under JSTD - 0333

Thank you very much,

Steel Camel

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