An Introduction to mems (Micro-electromechanical Systems)

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The most commonly used packages for sensors are usually based on derivatives of 

(Figure 29).   

 

Figure 30.  Types of traditional IC packaging [32]. 

Each of these packages has been adapted in one form or another for the packaging of silicon 

sensors.  Since the substrate on many integrated circuits requires an electrical connection to 

bias it, sensor dies are usually mounted to a die attach pad in the package using a conductive 

bond.  The die attach pad is typically joined to a metal lead frame with wire bonds providing 

the electrical connections to the lead frame fingers.  Various bonding media include AuSi 

eutectic bonding, epoxy bonding (conductive or insulating depending on filler material) and 

glass usually loaded with silver.  The package is subsequently formed by plastic moulding (as 

in the case of moulded plastic packages), sealed ceramic or metal caps (ceramic packages), or 

with a brazed metal cap to the base of a metal package. 

Wire bonding is still the most common technique for electrically connecting the die and 

mechanical stress applied to the die, the minimum spacing, the used wire alloys and the 

possibility of wire adjustment. 

In flip-chip (FC) technology the chips are bonded face down to a substrate via bumps; 

simultaneously forms all the electrical and mechanical connections between the chip and the 

substrate.