Encapsulated wafer-level chip scale (WLSCP) pedestal packaging
Consistent with an example embodiment, there is semiconductor device assembled to resist mechanical damage. The semiconductor device comprises an active circuit defined on a top surface, contact areas providing electrical connection to the active circuit. There is a pedestal structure upon which the active circuit is mounted on an opposite bottom surface; the pedestal structure has an area smaller than the area of the active device. An encapsulation, consisting of a molding compound, surrounds the sides and the underside of the active device and it surrounds the contact areas. The encapsulation provides a resilient surface protecting the active device from mechanical damage. A feature of the embodiment is that the contact areas may have solder bumps defined thereon.
1. A method for assembling a WLCSP semiconductor device having contact areas defined thereon, the method comprising:
defining a pedestal mounting strip per semiconductor device die thickness and surface area, the pedestal mounting strip have a topside and an underside;
fabricating the pedestal mounting strip out of a molding compound, the pedestal mounting strip having a grid of pedestals on the topside, each one of the grid pedestals having a surface area smaller than the surface area of the underside of the semiconductor device;
die attaching the semiconductor device onto the surface of each one of the grid pedestals, the semiconductor device forming an overhang on each one of the grid pedestals;
protecting the contact areas with a release foil before encapsulating each one the WLCSP devices;
encapsulating each one of the semiconductor devices on the pedestal mounting strip, assuring the encapsulant surrounds the semiconductor devices and flows under the overhang of each semiconductor device;
removing the release foil after encapsulating each one of the WLCSP devices; and
marking each one of the semiconductor devices in the corresponding position on the underside of the pedestal mounting strip.
2. The method as recited in claim 1 , wherein the contact areas include, solder bumps, pad landings of solderable metal, copper/tin alloy.
3. A method for assembling a wafer level chip scale processed (WLCSP) device having solder bumps defined thereon, the method comprising:
defining a pedestal mounting strip per WLCSP device die thickness and surface area, the pedestal mounting strip have a topside and an underside;
fabricating the pedestal mounting strip out of a molding compound, the pedestal mounting strip having a grid of pedestals on the topside, each one of the grid pedestals having a surface area smaller than the surface area of the underside of the WLCSP device;
die attaching the WLCSP device onto the surface of each one of the grid pedestals, the WLCSP device forming an overhang on each one of the grid pedestals;
encapsulating each one of the WLCSP devices on the pedestal mounting strip, and assuring that the encapsulant surrounds the WLCSP devices and flows under the overhang of each WLCSP device;
protecting the solder bumps with a release foil before encapsulating each one the WLCSP devices;
removing the release foil after encapsulating each one of the WLCSP devices; and
marking each one of the WLCSP devices in the corresponding position on the underside of the pedestal mounting strip.
4. The method as recited in claim 3 , wherein during the fabricating of the pedestal mounting strip, a metal shield is attached to the underside.
5. The method as recited in claim 3 further comprising,
singulating the encapsulated and marked WLCSP devices.
6. The method as recited in claim 3 , wherein the pedestal mounting strip comprises an organic compound selected from the following: epoxy molding compound, polyimides.
7. The method as recited in claim 3 wherein each one of the grid pedestals is of a shape of a regular polygon of at least 3 sides.
8. The method as recited in claim 7 , wherein the shape of each one of the grid pedestals is rectangular, square, or circular.
9. A semiconductor device assembled to resist mechanical damage, the semiconductor device comprising:
an active circuit defined on a top surface and contact areas providing electrical connection to the active circuit, wherein the contact areas have solder bumps thereon;
a release foil formed on the solder bumps before encapsulating the semiconductor device;
the release foil removed from the solder bumps after encapsulating the semiconductor device;
a pedestal structure upon which the active circuit is mounted on an bottom surface, wherein the pedestal structure has an area smaller than the area of the active device; and
encapsulation consisting of a molding compound surrounding the sides and the underside of the active device and surrounding the solder bumps, wherein the encapsulation provides a resilient surface protecting the active device from mechanical damage.
10. The semiconductor device as recited in claim 9 , wherein the pedestal structure is selected from one of the following:
directly formed onto a metal strip and the pedestal structure is integral to it;
the pedestal structure is separate piece which has been placed and attached to a metal substrate; and
the pedestal structure is formed out of molding compound.
11. The semiconductor device as recited in claim 9 , wherein the contact areas are solder bumps.