Charles, that standard is in revision at the present time.  There is a subset working group of some JEDEC and some IPC members preparing the draft; it hasn't been released for general committee review and comment yet but probably will be in late summer or early fall.

In the meantime, I've included both the IPC committee leader (Steve Martell, Sonoscan) and the JEDEC committee leader (Jack McCullen, Intel) on this reply and they may be able to provide understanding for your questions below as they apply to the currently published standard.

Cordially,
Jack

==========================================
APEX - the industry's premier trade show in Electronics
Manufacturing, January 16-18, 2001, San Diego, California.
More information on website www.apex2001.org
--------
Jack Crawford, IPC Director of Assembly Standards and Technology
2215 Sanders Road, Northbrook IL  60062-6135
[log in to unmask] 
847-790-5393
fax 847-509-9798

>>> <[log in to unmask]> 07/06/00 11:59AM >>>
I have been given the priveledge of revising our procedure to comply with J-STD
033. I have come across a couple of problems and hope you can help. First
problem is moisture barrier bag is supposed to have a water vapor transmission
rate of  .002 g/100in sq. But the materials I have found (3M 3300, SCC
DRI-Shield 2000 ) list wvtr of .02g/ 100in sq. and claim to meet the
requirements, is there a typo in the standard?
Next is section 6.3.2.2. To determine how much dessicant to put in a dry pack
bag you must know how much water vapor a unit of dessicant will absorb at 10%
humidity but doesn't tell you how to determine this. Also the formula given, if
you assume that the dessicant will absorb 2.85g of waetr vapor at 10% and that
the WVTR is really .02g/ 100 in sq would require 8 units in a 10"X16" bag,
pretty much the standard size that our IC's come in. Doesn't leave a lot of room
for parts. Our suppliers are only including 1 unit when they package. So are my
suppliers not doing it right or is my math wrong? Thank you in advance.

Charles Caswell
Process Lead, PCB
Frontier Electronics Systems
Stillwater OK.

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################