We also bake moisture sensitive parts in our facility but we are currently 
looking at an L-BAR sealer to reseal the vapor barrier bags immediately 
after opening to cut down on baking cycles and handling issues. Has anyone 
explored this procedure? We know before resealing the vapor barrier bags we 
will have to include desacent pouches and humidity indicators in each 
bag.Has there been any test to determine if this is effective or do we also 
need a vacuum system to remove all air from the barrier bags before 
resealing to control humidity?

Thanks in advance!
 ----------
From: TechNet-request
To: technet
Subject: Re: Moisture
Date: Monday, January 29, 1996 8:40AM


>Moisture / Surface Mount Plastic Packages / Cracking / Popcorning
>
>Do you bake your SMT IC's prior to IR reflow?

WE CURRENTLY BAKE BGA'S ONLY.HOWEVER, WE ARE CURRENTLY EVALUATING THE
NECESSITY OF BAKING QFP'S.
>
>If not, can I assume that your IC's are stored in sealed vapor barrier
>bag, prior to IR reflow?

YES.
>
>Are your parts received from the supplier, or vendors in vapor barrier
>bags with an indicator card?

YES, MSD (MOISTURE SENSITIVE DEVICES AS LABELED FROM VENDOR) ARE.
>
>I find it difficult to get IC's from the suppliers in vapor barrier bags,
>some parts are in barrier bags, but the majority are not, that means
>we must bake our IC's prior to IR reflow.

ALL IC'S, OR JUST MSD'S?? YOU ARE ASSUMING YOU WILL HAVE A PROBLEM WITH
IC'S??
>
>How do you stand on the the issue, bake or no bake, IC's prior to IR
>reflow?

WE HAVE HAD ALMOST NO PROBLEM WHICH WOULD REQUIRE US TO BAKE IC'S! HOWEVER,
WE HAVE PERFORMED ANALYSIS AND FOUND NO CORRELATION BETWEEN HIGH HUMIDITY
MONTHS (AT LEAST IN THIS AREA) AND INCREASED PLASTIC PARTS FAILURE. ARE THE
DEFECTS YOU ARE FINDING (I AM ASSUMING YOU HAVE SOME) ACTUALLY
HUMIDITY/PLASTIC PART CRACKING PROBLEMS??
>
>
>
 --------------------------------------
Jeffery L. Hempton                     Phone: 219-429-7335
Mail Stop:25-31  Fax:   4688  Email: [log in to unmask]
MESC, 1313 Production Road, Fort Wayne, IN 46808

"And the men who hold high places, must be the ones who start,
  To mould a new reality, closer to the heart.
Philosophers and Ploughmen, each must know his part,
  To sow a new mentality, closer to the heart."--Rush-A Farewell to Kings.