SAM: Main Issues in Plastic Encapsulated Systems

Plastic Encapsulated COTS

Plastic Encapsulated offers:

• Lower procurement cost.
• Shorter procurement time.
• More performance and functionality available.
• Reduced size and weight.

An inherent risk of PEMs is related to:

• Lack of hermeticity.
• The mismatch with the thermomechanical properties of the inorganic internal part.

Definitions

Delamination: Lack of adhesion at the interface between different materials; typically between the molding compound and an internal inorganic part.

Crack: Fracture in the bulk or on the surface of a given material, either the molding compound or internal inorganic parts (for instance the die surface).

Void: Lack of material within the bulk for instance within the die attach or in the molding compound due to improper injection

Lack of hermeticity

Contamination and moisture ingress and accumulation build-up result in metal corrosion. Occasionally, when the temperature rises, additional cracking occurs due to an effect known as popcorn cracking.

The actions that cause such contamination and accumulation of moisture are:

• Delamination on a surface breaking part
• Delamination on the die/paddle surface
• Cracks/void from the external surface to an internal feature

CTE Mismatch

Shear-induced damage of the die passivation produces metallic smearing (metallic tracks) and are caused by delamination on the die surface.

Bond wire degradation due to shear is connected by Cracks/void intersecting a bond wire.

Poor thermal dissipation is occasioned for Lack of adhesion or voids in the die attach.