Semiconductor device packaging having pre-encapsulation through via formation using lead frames with attached signal conduits
View Patent ↗A semiconductor device package having pre-formed and placed through vias and a process for making such a package is provided. One or more signal conduits are coupled to a lead frame that is subsequently embedded in an encapsulated semiconductor device package. The free end of signal conduits is exposed while the other end remains coupled to a lead frame. The signal conduits are then used as through package vias, providing signal-bearing pathways between interconnects or contacts on the bottom and top of the package and the leads.
1. A method for packaging an electronic device assembly, the method comprising:
providing a lead frame assembly comprising a lead frame and one or more signal conduits attached to the lead frame, wherein
each of the one or more signal conduits is coupled at a first end to a corresponding lead of the lead frame, and
the first end of each signal conduit is coupled to a free end of the corresponding lead;
placing the lead frame assembly in a first area for the electronic device assembly;
placing a first electronic device in a second area for the electronic device assembly,
wherein the second area is within a perimeter defined by the lead frame assembly;
forming an encapsulant over and around sides of the first electronic device and over and around sides of the lead frame assembly; and
exposing a second end of a signal conduit of the one or more signal conduits, wherein the signal conduit forms a conductive via through the encapsulated electronic device assembly.
2. The method of claim 1 further comprising:
assembling the lead frame assembly, wherein said assembling comprises
providing the lead frame,
forming a photoresist layer on the lead frame,
forming openings in the photoresist layer where signal conduits are desired,
depositing a conductive material in the openings in the photoresist layer, and
stripping the photoresist layer from the lead frame.
3. The method of claim 1 further comprising:
assembling the lead frame assembly, wherein said assembling comprises
providing the lead frame,
forming one or more inner leads, and
bending at least a portion of a lead of the one or more inner leads, wherein the at least the portion of the lead forms approximately a right angle to the plane of the lead frame subsequent to said bending.
4. The method of claim 3 wherein said forming the one or more inner leads comprises one of etching the lead frame or stamping the lead frame.
5. The method of claim 1 further comprising:
assembling the lead frame assembly, wherein said assembling comprises
providing a lead frame blank,
performing a first etch to form the one or more signal conduits in desired locations, and
performing a second etch to form leads from the lead frame blank.
6. The method of claim 1 further comprising:
assembling the lead frame assembly, wherein said assembling comprises
providing the lead frame,
forming one or more inner leads,
forming one of a hole or depression on one of the one or more inner leads, wherein the hole or depression is configured to receive a signal conduit of the one or more signal conduits, and
pressing the signal conduit into the hole or depression, wherein the signal conduit is mechanically locked into the hole or depression.
7. The method of claim 1 wherein said exposing further comprises removing a portion of the encapsulant from the electronic device assembly.
8. The method of claim 7 wherein said removing further comprises one of:
grinding the encapsulant from the electronic device assembly to a depth matching the end of the signal conduit; and
laser ablating the encapsulant from the electronic device assembly to a depth matching the end of the signal conduit.
9. The method of claim 7 wherein said exposing further comprises performing said forming the encapsulant exposes the ends of the conduit without removing a portion of the encapsulant.
10. The method of claim 1 wherein the second end of the signal conduit comprises a structure comprising one or more of a solder ball, a gold stud bump, and a copper stud bump.
11. The method of claim 1 further comprising:
separating the electronic device assembly from one or more other electronic device assemblies, wherein
the method for packaging forms a panel of electronic device assemblies,
said separating comprises cutting at least a portion of the lead frame from the electronic device assembly, and
said cutting electrically isolates one or more signal conduits and associated leads from one or more other signal conduits and associated leads.
12. The method of claim 1 further comprising:
providing a double-sided adhesive tape disposed on a carrier, wherein said placing the lead frame assembly comprises placing the lead frame assembly on the tape with a side down that is not in contact with the signal conduits;
exposing the side of the lead frame assembly that is not in contact with the signal conduits, after said forming the encapsulant;
forming, after said exposing the side of the lead frame assembly, a first interconnect structure on a first side of the electronic device assembly, wherein the first interconnect structure couples a first contact on the first electronic device to a portion of the lead frame attached to a signal conduit; and
forming, after said exposing the second end of the signal conduit, a second interconnect structure on a second side of the electronic device assembly, wherein the second interconnect structure is coupled to the signal conduit.
13. The method of claim 1 further comprising:
coupling a first contact of the first electronic device to a portion of the lead frame attached to a signal conduit, wherein said coupling is performed using one of a wire bond or a flip chip.
14. A method for packaging an electronic device assembly, the method comprising:
forming a lead frame;
coupling one or more signal conduits to corresponding leads of the lead frame, wherein said forming and coupling provides a lead frame assembly, and
a first end of each signal conduit of the one or more signal conduits is coupled to a free end of a corresponding lead of the lead frame;
placing the lead frame assembly in a first area for the electronic device assembly;
forming an encapsulant over and around sides of the lead frame assembly, wherein
a signal conduit of the one or more signal conduits forms a conductive via through the encapsulated electronic device assembly.
15. The method of claim 14 wherein said coupling the one or more signal conduits to corresponding leads of the lead frame comprises:
forming a photoresist layer on the lead frame;
patterning the photoresist layer to provide a hole from the top of the photoresist layer to a contact position of the lead frame;
forming a conductive layer in the photoresist hole and contacting the contact position; and
removing the photoresist layer from the lead frame.
16. The method of claim 15 wherein said forming the lead frame comprises: etching frame material to form the leads of the lead frame.
17. The method of claim 14 wherein said coupling the one or more signal conduits to corresponding leads of the lead frame comprises:
providing a lead frame blank; and
selectively etching the lead frame blank to form a frame of the lead frame, the leads of the lead frame, and the one or more signal conduits.