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February 2000

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Subject:
From:
Ashok Dhawan <[log in to unmask]>
Reply To:
Date:
Tue, 8 Feb 2000 11:36:19 -0800
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I have three questions on moisture sensitive devices:

1. What is general practice on incoming / receiving inspection of
moisture sensitive devices- which boils down to mostly FPDs and BGAs ?
Traditionally, FPD packs were opened only at time of use but IPC STD 033
appears to be allowing all ( does not state clearly ) as resort to room
temp desiccation as long as the exposure time is limited to max 8 hours.

2. New std IPC J-STD-033 states MBB with property WVTR as 0.002 while
J-STD-786A specifies it as 0.020. When contacted MBB suppliers, they
mostly states 0.020 in their spec sheet- can any one clarify ? I am also
contacting IPC to check ?
3. As a user, what is general recommendation to reseal bags with
ordinary bag sealer or vacuum sealer ? Why we need vacuum in any case.
If it is moisture, wht not add extra desiccant to take care of moisture
from entrapped air and unbaked carriers. IPC std does not address this
query ?

Ashok

--

Ashok Dhawan P.Eng
Engineering
C-Mac Electronic Systems Inc.
1455 Mountain Avenue
Winnipeg, Manitoba R2X 2Y9
Canada
Phone: (204) 631-7208
Fax: (204) 631-7294
E-mail: [log in to unmask]
www.cmac.ca



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