Semiconductor device packaging having substrate with pre-encapsulation through via formation
View Patent ↗A method for forming through vias in a semiconductor device package prior to package encapsulation is provided. One or more signal conduits are formed through photolithography and metal deposition on a printed circuit substrate having interconnect pads. After removing photoresistive material, the semiconductor device package is built by encapsulating the signal conduits along with any semiconductor die, wire bonding, and other parts of the package. Free ends of each signal conduit are exposed and the signal conduits are used as through vias to provide signal-bearing pathways between connections from a top-mounted package to a printed circuit substrate interconnect and electrical contacts of the semiconductor die or package contacts. Using this method, signal conduits can be provided in a variety of geometric placings on the printed circuit substrate for inclusion in a semiconductor device package. A semiconductor device package incorporating the pre-fabricated through vias is also provided.
1. A method for packaging an electronic device assembly, the method comprising:
providing a printed circuit substrate having an interconnect;
forming one or more signal conduits on the printed circuit substrate, wherein
a first end of each signal conduit contacts a conductive pad on a major surface of the printed circuit substrate, and
the conductive pad is coupled to the interconnect;
forming an encapsulant over and around sides of the one or more signal conduits, wherein said forming the encapsulant is performed subsequent to said forming the one or more signal conduits; and
exposing a second end of each signal conduit of the one or more signal conduits, wherein each signal conduit forms a conductive via through the electronic device assembly.
2. The method of claim 1 wherein said forming the one or more signal conduits comprises:
forming a photoresist layer over the printed circuit substrate;
forming one or more openings in the photoresist layer corresponding to where the one or more signal conduits are desired;
depositing a conductive material in the openings in the photoresist layer; and
stripping the photoresist layer from the printed circuit substrate.
3. The method of claim 2 further comprising:
performing an under bump metallization on one or more of the one or more signal conduits, wherein said under bump metallization is performed prior to said forming the encapsulant.
4. The method of claim 1 wherein said exposing the second end of each signal conduit comprises controlling said forming the encapsulant to a thickness less than or equal to a length of the signal conduits.
5. The method of claim 1 wherein said exposing the second end of each signal conduit comprises laser ablating the encapsulant from an area around the second end of each signal conduit.
6. The method of claim 1 further comprising:
placing a first electronic device on the printed circuit substrate in an area for the electronic device assembly, wherein
said forming the encapsulant further comprises forming the encapsulant over and around sides of the first electronic device.
7. The method of claim 6 further comprising:
electrically coupling the first electronic device to the interconnect prior to said forming the encapsulant.
8. The method of claim 7 wherein said electrically coupling comprises forming a wire bond from a contact pad of the first electronic device to a wire bond pad formed on the major surface of the printed circuit substrate.
9. The method of claim 7 wherein said electrically coupling comprises contacting a conductive pad of the first electronic device to a pad formed on the major surface of the printed circuit substrate.
10. The method of claim 1 further comprising:
placing a second electronic device assembly on the exposed second end of one or more signal conduits such that the second electronic device assembly is electrically coupled to the one or more signal conduits.
11. A method for packaging an electronic device assembly, the method comprising:
forming a photoresist layer on a printed circuit substrate;
forming one or more openings in the photoresist layer, wherein the one or more openings extend from the surface of the photoresist layer to contacts on the printed circuit substrate;
depositing a conductive material in the openings in the photoresist layer to form corresponding one or more signal conduits;
stripping the photoresist layer from the printed circuit substrate and the signal conduits; and
forming an encapsulant over and around sides of the one or more signal conduits and over the printed circuit substrate; and
exposing an end of the one or more signal conduits, wherein said exposing the end comprises removing a portion of the encapsulant from the electronic device assembly.
12. The method of claim 11 further comprising:
placing an electronic device on the printed circuit substrate in an area for the electronic device assembly, after said stripping the photoresist layer from the printed circuit substrate; and
forming the encapsulant over and around sides of the electronic device.
13. The method of claim 11 wherein said removing the portion of the encapsulant comprises one of:
laser ablating the encapsulant from the electronic device assembly to a depth at least matching the end of the signal conduits,
grinding the encapsulant from the electronic device assembly to a depth at least matching the end of the signal conduits, or
etching the encapsulant from the electronic device assembly to a depth at least matching the end of the signal conduits.