Methods for packaging image sensitive electronic devices
View Patent ↗The invention provides methods for packaging for electronic devices that are light or other radiation-sensitive, such as image sensors including CCD or CMOS chips. In one embodiment of the invention, an image sensor package is assembled by surrounding a chip with a barrier of transfer mold compound and covering the chip with a transparent lid. In another embodiment of the invention, the perimeter area of a chip, including interconnections such as wire bonds and bond pads, is encapsulated with a liquid dispensed epoxy, and a transparent lid is attached. In yet another embodiment of the invention, chip encapsulation is accomplished with a unitary shell of entirely transparent material. In yet another embodiment of the invention, a substrate-mounted chip and a transparent lid are loaded into a transfer mold that holds them in optimal alignment. The transfer mold is then filled with molding compound to encapsulate the chip and interconnections, and to retain the transparent lid.
1. A method for assembling at least one package containing an electronic device sensitive to light or other radiation comprising:
mounting the electronic device on a carrier substrate comprising a contiguous planar structure having at least one conductive trace thereon, the at least one conductive trace having a first end comprising a terminal pad on a first surface of the carrier substrate and a second end comprising an attachment pad on a second, opposing surface of the carrier substrate;
providing at least one electrical interconnection between a bond pad on the electronic device and the first end of the at least one conductive trace;
forming a molded barrier on the carrier substrate prior to mounting the electronic device, the molded barrier surrounding a central exposed area that contains the electronic device and the at least one electrical interconnection; and
filling the central exposed area of the molded barrier with a clear compound to form a transparent shell that encapsulates the electronic device, the bond pad, and the at least one electrical interconnection.
2. The method according to claim 1 , further comprising supporting a transparent lid on a ledge formed on an inner perimeter of the molded barrier.
3. The method according to claim 1 , further comprising forming a surface of the transparent shell into the shape of a lens.
4. The method according to claim 1 , further comprising fixing a transparent lid over the central exposed area by applying an activated adhesive between an outer perimeter of the transparent lid and an inner perimeter of the molded barrier and setting the activated adhesive.
5. The method according to claim 1 , wherein mounting the electronic device comprises providing an image sensor.
6. The method according to claim 1 , further comprising selecting the electronic device to comprise a solid-state device comprising at least one of a charge coupled device, a complementary metal-oxide semiconductor and an erasable programmable read-only memory.
7. The method according to claim 6 , further comprising fabricating the electronic device to comprise a plurality of semiconductor devices.
8. The method according to claim 1 , further comprising forming the carrier substrate of a material comprising at least one of plastic, FR-4 and BT.
9. The method according to claim 8 , further comprising:
attaching at least one discrete conductive element to the second end of the at least one conductive trace of the carrier substrate.
10. The method according to claim 9 , further comprising:
mounting a plurality of electronic devices onto the carrier substrate; and
dividing the carrier substrate into separate pieces, each of the pieces comprising a package including one electronic device of the plurality of electronic devices.