1 recommendations for long -term transistor storage ? north america tel: 800.366.2266 / fax: 978.366.2266 ? europe tel: 44.1908.574.200 / fax: 44.1908.574.300 ? asia/pacific tel: 81.44.844.8296 / fax: 81.44.844.8298 visit www.macomtech.com for additi onal data sheets and prod uct information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or information contained herein without notice. advanced: data sheets contain information regarding a product m/a-com technology solutions is considering for development. performance is based on target specifications, simulated results, and/or prototype measurements. commitment to develop is not guaranteed. preliminary: data sheets contain information regarding a product m/a-com technology solutions has under development. performance is based on engineering tests. specifications are typical. mechanical outline has been fixed. engineering samples and/or test data may be available. commitment to produce in volume is not guaranteed. application note AN4002 rev. 1 introduction the purpose of this document is to provide users wi th recommendations for storing transistors when the user shelf life will exceed 12 months (from receipt of parts). long-term storage when long-term storage is necessary, the fo llowing techniques should be considered: dry atmosphere cabinets. storage cabinets which maintain low humidity by purging with dry air or nitrogen at 25 5c and <5% relative humidity (rh). ? the cabinets should be capable of recovering to their st ated humidity rating within one hour from routine ex- cursions such as door opening/closing. moisture barrier bags (mbb). these bags are designed to restrict the transmission of water vapor and used to pack moisture sensitive devices. ? the moisture barrier bag should meet mil-prf-81705, type i requirem ents for flexibility, esd protection, mechanical strength, and puncture resistance. the bags must be heat sealable. the water vapor transmis- sion rate (wvtr) should be 0.002 gm/100 in2 in 24 hrs at 40c after flex testing per condition ??e??astm f 392. the wvtr is measured using astm f 1249. desiccant. desiccant is an absorbent material used to maintain a low relative humidity. ? the desiccant material should meet mil-d-3464, type ii. desiccant should be dustless, noncorrosive, and absorbent to amounts specified in the standard. the desiccant should be packaged in moisture permeable bags or pouches. the amount of desiccant used, per moisture barrier bag, should be based on the bag sur- face area and wvtr in order to limit the interior relative humidity in the mbb to less than 10% at 25c. humidity indicator card (hic). this is a card on which a moisture-sensitive chem ical is applied such that it will make a significant, perceptible change in color (hue), ty pically from blue (dry) to pink (wet) when the indicated relative humidity is exceeded. ? the hic is packed inside the moisture-barrier bag, to ai d in determining the level of moisture to which the moisture-sensitive devices have been subjected. at minimu m, the hic should have three (3) color spots with sensitivity values of 5%, 10% and 60% rh. summary these recommendations are intended to be general in nature, as user storeroom / factory floor environments, and applications vary greatly. when it is known or anticipated that received parts wi ll have a shelf life exceeding 12 months, use of the tech- niques, or combination of techniques described provide uniform methods to protect transistors during long-term storage. as always, proper esd precautions should be observed during handling and assembly.
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