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.
1. A method for assembling a package containing an electronic device sensitive to light or other radiation comprising:
mounting the electronic device on a carrier substrate having at least one conductive trace thereon, the at least one conductive trace having a first end and a second end;
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;
encapsulating the first end of the at least one conductive trace, the at least one electrical interconnection and the bond pad of the electronic device with a nonconductive material dispensed in liquid form;
covering a surface of the electronic device with a transparent lid;
curing the liquid nonconductive material to at least a semisolid state; and
retaining the transparent lid by an adhesive interface with the nonconductive material.
2. The method according to claim 1 , wherein the electronic device comprises an image sensor.
3. The method according to claim 1 , wherein the electronic device comprises a solid-state device selected from a group consisting of a charge coupled device, a complementary metal-oxide semiconductor and an erasable programmable read-only memory.
4. The method according to claim 3 , wherein the electronic device further comprises a chip stack.
5. The method according to claim 1 , wherein the carrier substrate is made of a material selected from a group consisting of plastic, FR-4 and BT.
6. The method according to claim 5 , further comprising fabricating the electronic device to comprise a plurality of semiconductor devices.
7. 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.
8. The method according to claim 7 , further comprising: attaching at least one discrete conductive element to the second end of the at least one conductive trace of the carrier substrate.
9. The method according to claim 8 , wherein a plurality of the packages, each containing an electronic device, is formed onto a single carrier substrate and further comprising: dividing the single carrier substrate into separate pieces, each of the pieces comprising one of the packages.
10. A method for assembling a package containing an electronic device sensitive to light or other radiation comprising:
mounting an electronic device on a carrier substrate, the carrier substrate comprising at least one conductive trace having a first end and a second end;
forming at least one electrical interconnection between the first end of the at least one conductive trace and a bond pad on the electronic device;
dispensing a liquid nonconductive material around a perimeter of the electronic device to encapsulate the at least one electrical interconnection, the bond pad and the first end of the at least one conductive trace;
placing a transparent lid over the electronic device and in contact with the liquid nonconductive material; and
curing the liquid nonconductive material to at least a semisolid state to retain the transparent lid in position over the electronic device.
11. The method of claim 10 , wherein placing the transparent lid over the electronic device comprises placing the transparent lid directly against a surface of the electronic device.
12. The method of claim 10 , wherein placing the transparent lid over the electronic device comprises inserting a gasket between the electronic device and the transparent lid.
13. The method of claim 10 , further comprising forming a layer of molding compound over the liquid nonconductive material and in contact with a perimeter of the transparent lid.
14. The method of claim 10 , further comprising attaching at least one discrete conductive element to the second end of the at least one conductive trace of the carrier substrate.
15. The method of claim 10 , wherein mounting the electronic device on a carrier substrate comprises mounting a plurality of electronic devices onto a single carrier substrate.
16. The method of claim 15 , further comprising dividing the single carrier substrate into individual packages.
17. The method of claim 10 , wherein mounting an electronic device on a carrier substrate comprises mounting an electronic device comprising a chip stack on the carrier substrate.
18. The method of claim 10 , wherein mounting an electronic device on a carrier substrate comprises mounting an image sensor on the carrier substrate.
19. The method of claim 10 , wherein mounting an electronic device on a carrier substrate comprises mounting a solid state device on the carrier substrate, the solid state device selected from the group consisting of a charge coupled device, a complementary metal-oxide semiconductor and an erasable programmable read-only memory.