Device Storage, Shelf Life, and Soldering
All DALSA Semiconductor integrated circuits are manufactured using world class methods and materials and are designed to tolerate industry standard handling and board level processing without damage. However the solder mounting of devices onto boards can cause "pop corning" of certain types of surface mount packages if they have been improperly stored or handled. This package delamination occurs as excessive moisture within the package expands as a result of the rapid thermal changes experienced during solder mount operations. Adherence to proper storage and handling methods as described below will eliminate this risk.
Dry packing
It is important that the moisture content of SMDs is controlled in order to eliminate the possibility of this "popcorn" effect occurring during board solder processing. DALSA Semiconductor addresses this issue by baking all moisture sensitive SMD's to remove any moisture and then sealing under vacuum into industry standard dry packs containing a desiccant. These dry packs also provide electrostatic protection during shipping and storage.
The following table is a quide to which package types DALSA Semiconductor applies dry packing. However some products assembled in additional package types/lead counts because of die/design requirements, will also be dry packed.
| Dry Packing Criteria per Package Type | |
| SOIC | >28 leads |
| SSOP | >28 leads |
| QSOP | Not applied |
| TSOP | All lead counts |
| PSOP | All lead counts |
| PLCC | >84 leads |
| PQFP/MQFP | All lead counts |
| TQFP | All lead counts |
| LQFP | All lead counts |
| BGA/LBGA | All lead counts |
| MLP | >28 leads |
Floor life
Floor life is the time allowed between opening any dry pack and subsequent soldering operations and is defined for packages according to the standard JEDEC J-STD-020. Recommended floor life for DALSA Semiconductor dry packed products is indicated on the dry pack. Note that the safe floor life will be affected by the ambient environmental conditions.
| Recommended floor life conditions | ||
| JEDEC level | Dry packed | Floor life at 30°C/60%RH |
| 1 | no | Unlimited |
| 3 | yes | 168 Hours |
| 4 | yes | 72 Hours |
| 5 | yes | 48 Hours |
A rebake is recommended if storage conditions exceed either 30°C/60% or the quoted floor life.
Rebake for either 24 Hours at 125°C or 9 Hours at 140°C
The floor life clock is reset to zero following the rebake. However if the ambient conditions still do not meet those defined the product should be used immediately following the bake
N.B. Product may be stored indefinitely once the dry pack is opened provided that the ambient humidity does not exceed 20% RH. Humidity controlled dry-air or dry-nitrogen cabinets are recommended for this purpose.
Long Term Storage - Shelf Life
DALSA Semiconductor product may be stored for extended periods before use provided that storage conditions are well controlled. Evaluation of devices has shown solderability is acceptable after a period of three years from the time the tin/solder plate or solder dip was applied to the devices. Note that the date code on the device is the date of assembly / lead finish processing. Non dry pack devices should be shielded from electrostatic charge and stored in conditions not exceeding 30°C/60%RH.
Moisture sensitive product (SMD's) that are supplied by DALSA Semiconductor in dry packs will need to be rebaked as stated above and repackaged every twelve months unless stored in conditions not exceeding 20% RH.
Soldering Profile
The time and temperature profiles used in soldering operations vary tremendously and are dependent upon the soldering process, equipment and materials used. With the exception of Vapour phase which typically subjects devices to 215°C without pre-heat, most profiles involve a pre-heat stage of approximately 150°C for 30 seconds followed by the main solder reflow operation at 240°C with the peak temperature maintained for no more than 10 seconds. DALSA Semiconductor's devices will not be damaged by the use of such soldering profiles.
Moisture Sensitive SMD - Reliability Assessment
The moisture sensitivity of all SMD families is assessed as part of DALSA Semiconductor package qualifications. Devices are also preconditioned prior to certain stress tests carried out as part of our routine reliability monitoring programs. These provide us with confidence in the reliability of shipped product. Preconditioning conditions are chosen to simulate the worst case storage and soldering conditions experienced in use with exact conditions dependent upon the moisture sensitivity classification (as per JEDEC J-STD-020 & JESD22-A113). Preconditioning is applied as per JESD22-A113 prior to most stress tests, which include temperature cycling, biased damp heat and autoclave.
For dry packed SMD's the preconditioning sequence includes a soak at 30°C/60%RH with the duration equal to the floor life corresponding to the moisture sensitivity classification plus 4 hours.
For SMD's which are not dry packed, the precondition sequence includes a soak at 85°C/85% RH for 168 hours.
©2008 DALSA • Privacy Policy
Problems with this site?
E-mail the
webmaster.