There has been much industry activity lately on this topic. Basically, in 
1986 Ray Prasad and others from Intel presented data showing that plastic 
ICs undergoing surface mount soldering were delaminating or cracking and 
causing field failures.

The Surface Mount Council commissioned a white paper, which was finished 
in 1988. A special IPC task group, chaired by Prasad, then developed a 
specification--IPC-SM-786-- which defined levels (for classifying the 
susceptibility of certain types of components to delamination) and gave 
preconditioning and handling guidelines, including drypacks and nitrogen
storage.

In 1995, IPC released the "A" revision of IPC-SM-786. This industry 
standard is used by many manufacturers and suppliers. Other standards 
also available are JESD A112/A113 from JEDEC and EIA 4071A and ED407 from 
Electronics Industry Association Japan. The JEDEC and IPC standards are 
fairly similiar with regard to the specific requirements, although the IPC 
standard offers much more baackground information and tutorial.

Six levels of classification are designated in the standard. We have found 
the industry really only uses three or four of these, although a new 
level probably needs to be developed between the current levels 2 (1 year 
out of bag at less than 30C/60%RH) and 3 (1 week at 30C/60%RH). For a 
full description of the baking parameters and handling, see the standard.

In March 1996, 30-odd industry participants (including John Tsutsui of 
Rockwell) attended an ITRI-SEMATECH sponsored workshop in Dallas at 
which we developed a number of industry needs. One of these is a single 
specification for classification and handling of moisture sensitive ICs. 
With that mandate, IPC and JEDEC formed a joint task group to carry out this 
goal. The first meeting of this task group is next week at the IPC 
office in Northbrook, IL. ANSI has designated J-STD-020 as the number for 
this future standard. 

It is important to note that Amkor and other component suppliers have 
shown that although delamination is a red flag, there is no one-to-one 
correlation between delam and failure.

IPC-SM-786A is available from IPC's order department: email 
[log in to unmask], or call 847-509-9700, ext. 348. Price is $15 for IPC 
members/30 for nonmembers.

Mike Buetow
IPC Technical Staff
2215 Sanders Road
Northbrook, IL 60062
P: 847-509-9700, ext. 335
F: 847-509-9798
[log in to unmask]



On Wed, 5 Jun 1996, David T. Novick wrote:

>      On 5 June 1996 a request from manufacturing engineering was placed for 
>      forwarding to TechNet.  This request is as follows:
>      
>      Several programs going into production will be using plastic parts.  
>      There parts tend to absorb moisture and will crack during the reflow 
>      process.  Since our entire experience has been with military 
>      packaging, we are not certain what to expect from plastic components.  
>      We are requesting information on the packaging and storage of these 
>      parts.  We also would like to know the baking parameters typically 
>      required to mitigate any risk during the soldering processes utilized 
>      throughout industry.  It is our understanding that if these parts are 
>      exposed to humidity for a period of time we need to vacuum bake them.  
>      However we do not know for what period of time and at what 
>      temperatures.  Since this is an area which is fairly new to us, we 
>      need all the feedback we can get.
>      
>      Thanks for your help.
>      
>      Rosaura Corral-Perez
> 
>