Popcorning = Cracking of the plastic component body during reflow. This 
is caused by moisture absorbed by the plastic, which then turns to steam 
during reflow. This situation can jeopardize long-term reliability of the 
part.

Delamination = Separation of the internal package interface; silicon to 
mold compound; mold compound to lead frame; silicon to die attach 
adhesive and paddle, etc. Delam is less prevalent than cracking (see 
above), but may result in wire bond degradation, which also can jeopardize 
the long-term reliability of the part.

I'm not positive about floating, but one definition is:

Floating = A connector mounting device that allows for connector body 
movement in order to ease its alignment with a mating part or assembly.

You may want to obtain a copy of IPC-SM-786A, "Procedures for 
Characterizing and Handling of Moisture/Reflow Sensitive ICs," which was 
published earlier this year. It provides tutorial background on component 
handling and reflow problems, in addition to the specifications for 
classifying and handling plastic surface mount ICs. Price: $15 IPC 
members, $30 nonmembers.

For a good general guide to terms and definitions, try IPC-T-50E, "Terms 
and Definitions for the Interconnecting and Packaging of Electronic 
Circuits." Price: $30 members, $60 nonmembers.

Both documents are available from IPC, 708-677-2850, ext. 348.

Mike Buetow
IPC Technical Staff
7380 N. Lincoln Avenue
Lincolnwood, IL 60646
P: 708-677-2850, ext 335
F: 708-677-9570
[log in to unmask]


On Tue, 15 Aug 1995 [log in to unmask] wrote:

> I could use some assistance in defining 'popcorn effect,' delamination,' and
> 'floating' as it applies to components (BGA, fine pitch packages).
> 
> Any other known common component level phenomena (seen during
> assembly/soldering) and words used to identify them would be much appreciated
> as well.
> 
> Thank you,
> Patrick Hassell
> Electronic Packaging Services
> (404) 524-0888
> [log in to unmask]
> 
>