Developmental Background
During package grinding for FOWLP (Fan-Out Wafer Level Package), a type of WLCSP, various materials with different grinding performances are processed, such as Si die, copper metal, mold resins, and insulating films (polyimide). Up until now, it was difficult to perform stable grinding on these materials simultaneously while preventing burring in the ductile materials, such as copper and resin.

Features
The GFCP series adopts porous vitrified-bonded wheels, which are excellent for ductile materials. Furthermore, by strictly controlling the hardness of the wheels, the technology can be used to process multiple types of package configurations and materials in order to meet the customer’s needs.

Developmental Background
In the thinning of WLCSP with bumps 100 µm and taller, it is common to perform grinding and polishing while absorbing the bumps by mounting a thick surface protective tape and controlling wafer unevenness. After wafer grinding, in order to enhance the strength, it is necessary to remove distortions on the ground surface generated by polishing. However, if the distortion is eliminated completely, the gettering effect* is lost and wafer failure is likely to occur due to heavy metal contamination.
Although DISCO has already developed the DPEG series of dry polishing wheels which can polish while maintaining the gettering effect, in some cases, polishing failures may occur in wafers with a thick surface-protective tape because the heat generated during processing cannot escape.

※Gettering effect: Forming crystal defects and distortions (= gettering site) on the backside of a Si wafer, capturing the impurities which cause metal contamination and affixing them to the getting site. Gettering DP wheels form a gettering site with minor scratches on the backside of the wafer and capture the heavy metal contamination.

Features of This Product
The DPEG-BP dry polishing wheel can control heat generation even when polishing bump wafers mounted on a thick surface-protective tape, achieving stable processing. Furthermore, just like the existing DPEG series of dry polishing wheels, the DPEG-BP polishing wheel achieves both a high die strength and a gettering effect.