In some dicing applications, cut depth (= blade height) needs to be controlled with high precision.
This blade height control function can be implemented by adding a height sensor to the dicing saw.
Two representative examples of this function in wafer dicing and packaging are as follows.

• DBG process - Measurement and cut depth control for Si wafer with flat surface
• Wettable Flank-QFN - Measurement for workpiece with large warpage, such as IC package, and cut depth tracking control

Height Control in DBG Process

In the DBG process, grooves are created using half-cut dicing, and the wafer is thinned and singulated through backgrinding.
To obtain high-quality die separation, it is important to control the depth of the cuts made with half-cutting so that die can be separated during Z2-axis grinding (fine grinding).

DBG (Dicing Before Grinding) Process

Height Control for Wettable Flank QFN

In conventional QFN packages (Quad Flat Non-leaded packages), as solder joints are formed at the bottom of the package, it is difficult to perform AOI (Automated Optical Inspection) when the wafer is bonded. However, in Wettable Flank QFNs, solder fillets are formed on the sidewalls, enabling easier appearance inspection. Thus, Wettable Flank QFNs have been widely adopted for applications that require high reliability, such as automotive applications.
In WF-QFNs, pockets to absorb solder are formed on the terminals through half-cut processing. Through control of the depth of the pockets, the height of the solder fillets is made uniform, which allows for easier appearance inspection.
To respond to requirements, such as mass production and handling workpiece warpage, various options can be selected for half-cut processing, such as the method to be used to secure the workpiece (tape/jig), height measurement, and blade height tracking control method.

QFN Package Processing

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