Internal Package and Die Contamination

   

Internal package contamination is the presence of a foreign material, whether attached or unattached, anywhere inside the package of the device.  Since certain contaminants can affect the performance and reliability of the device, internal contaminants need to be identified promptly and, if necessary, traced to their root cause. Corrective actions may then be implemented to prevent recurrence. 

       

The criteria for rejecting internal contamination depends on its location, extent, and composition. Internal contaminants are rejected generally because of the quality and reliability risks involved, mainly with regard to bond pad/die corrosion and electrical performance degradation in the form of electrical shorts, excessive current leakage between active metallizations, and surface charging.

   

Internal contaminants can come from anywhere. Common internal contaminants include but are not limited to the following : organic residues on leadframes, die attach material on the die; epoxy resin bleed-out on the package and bonding posts; silicon sawdust; unetched glass on bond pads; organic contaminants containing halides such as spittle; solder balls inside the cavity; and molten/burned lint and fibers from production materials.

 

   

   

Figure 1.  Internal contaminants on the die (left), die paddle (center); and die backside (right)

    

Examples of FA techniques used for identifying internal contaminants include: EDX Analysis, FTIR Analysis, Auger Analysis, and Ion Chromatography.

   

In certain cases, reliability assessment of samples with internal contamination is required.  The corrosive effects of internal contaminants may be accelerated by PCT and HAST.

 

See also:   External ContaminationPackage Failure MechanismsFailure Analysis

            

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