Scott,

The key concern relative to excessive moisture is related to the maximum
floor life of moisture-sensitive components. This is a critical quality and
reliability concern applicable for all plastic encapsulated devices (PLCC,
QFP, SOIC, TSOP and PBGAs, among others). These parts are classified by the
manufacturer according to their sensitivity level (1 to 6) which equates to
their maximum floor life at conditions below 30C/60%RH once they are removed
from their protective dry bags, until final reflow. I recommend that you
download the joint IPC/JEDEC standard J-STD-033 for more details (free
download at www.jedec.org). If your manufacturing environment is
significantly different from 30C/60% RH you should de-rate (increase or
decrease) the maximum floor life based on table 5 of the above document. The
phenomena of moisture sensitivity is related to a combination of moisture
and temperature and generally not a concern if the body temperature of the
parts do not exceed 200C, which is why it is only a concern during solder
reflow.

Francois Monette
Cogiscan Inc.
50 De Gaspe, Suite A5
Bromont, Quebec, Canada, J2L 2N8
Tel : (450)534-2644
Fax: (450)534-0092
www.cogiscan.com

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------