Integrated circuit with sewn interconnects
A packaged integrated circuit (IC) device includes a flexible substrate having contact pads, an IC die mounted on the substrate and electrically connected to the contact pads, and conductive threads sewn into the substrate. The conductive threads have proximal ends electrically connected to corresponding ones of the contact pads with conductive bumps. The conductive threads eliminate the need for a complicated multi-layer substrate structure for interconnect fan-out so the substrate may be formed of a variety of materials such as cloth or paper.
1. A packaged integrated circuit (IC) device, comprising:
a substrate having a first plurality of contact pads;
an IC die mounted on the substrate and electrically connected to the first plurality of contact pads;
a first conductive thread sewn into the substrate, wherein:
the first conductive thread has a proximal end and a distal end;
the proximal end is electrically connected to a corresponding one of the contact pads by a corresponding conductive bump; and
the proximal end pierces the corresponding contact pad of the first plurality of contact pads.
2. The device of claim 1 , wherein:
the substrate further comprises:
a plurality of under-die contact pads;
a plurality of conductive balls; and
a plurality of conductive traces;
the IC die has a plurality of IC-die contact pads; and
each of the under-die contact pads is:
electrically connected to at least one of the contact pads by way of at least one of the conductive traces; and
electrically connected to a corresponding one of the IC-die contact pads by way of a corresponding one of the conductive balls.
3. The device of claim 1 , wherein the first conductive thread is a carbon nanotube (CNT) thread.
4. The device of claim 1 , further comprising a second thread, wherein:
the first conductive thread and the second thread are sewn together to form a lock stitch;
the first conductive thread is one of a needle thread and a bobbin thread; and
the second thread is the other of the needle thread and the bobbin thread.
5. The device of claim 4 , wherein the second thread is a non-conductive thread.
6. The device of claim 1 , further comprising a distal conductive bump electrically connected to the distal end of the first conductive thread and securing the distal end of the first conductive thread to the substrate, wherein the distal conductive bump is adapted for electrical connection to a component external to the IC device.
7. The device of claim 1 , wherein:
each contact pad of the first plurality of contact pads has a corresponding conductive thread sewn into the substrate; and
each corresponding conductive thread has (i) a distal end and (ii) a proximal end that is electrically connected to the corresponding contact pad by a corresponding conductive bump.
8. The device of claim 1 , further comprising a plurality of distal contact pads and corresponding electrically connected distal traces, wherein:
the distal end of the first conductive thread is electrically connected to a corresponding one of the distal contact pads.
9. The device of claim 8 , wherein the distal end of the first conductive thread pierces through the corresponding distal contact pad.
10. The device of claim 1 , further comprising an encapsulant that covers the IC die and at least part of the substrate.
11. The device of claim 10 , wherein:
the first conductive thread is also sewn into the encapsulant;
the encapsulant includes recesses corresponding to the first plurality of contact pads;
the proximal end of the first conductive thread is located within a corresponding one of the recesses; and
the corresponding one of recesses comprises solder that electrically connects the proximal end of the first conductive thread to the corresponding contact pad.
12. The device of claim 10 , wherein:
the first conductive thread is also sewn into the encapsulant;
the encapsulant includes metallic pillars corresponding to the first plurality of contact pads; and
the proximal end of the first conductive thread is electrically connected to the corresponding contact pad by way of the corresponding metallic pillar.
13. The device of claim 11 , wherein the first conductive thread is sewn into the substrate but not the encapsulant.
14. The device of claim 1 , further comprising:
one or more additional IC dies;
corresponding pluralities of additional IC die contact pads;
corresponding conductive threads having proximal and distal ends; and
corresponding conductive bumps connecting the proximal ends of the corresponding conductive threads to corresponding ones of the additional IC contact pads.
15. The device of claim 1 , wherein the IC die is part of an IC die carrier mounted on the substrate, wherein the IC die carrier comprises:
the IC die;
a carrier substrate upon which the IC die is mounted; and
an encapsulant that covers the IC die and at least a portion of the carrier substrate.
16. A packaged integrated circuit (IC) device, comprising:
a substrate having a plurality of under-die contact pads, a plurality of contact pads, and a plurality of conductive traces electrically connecting the under-die contact pads with respective ones of the contact pads;
an IC die mounted on the substrate and electrically connected to the under-die contact pads;
a first conductive thread sewn into the substrate, wherein the first conductive thread has a proximal end electrically connected to a corresponding one of the contact pads with a corresponding conductive bump;
a second, non-conductive, thread sewn together with the first conductive thread using a lock stitch, wherein the first conductive thread is one of a needle thread and a bobbin thread, and the second thread is the other of the needle thread and the bobbin thread; and
an encapsulant that covers the IC die and the corresponding conductive bump that connects the first conductive thread to the one of the contact pads.
17. A method for packaging an integrated circuit (IC) device, the method comprising:
providing a substrate having a plurality of contact pads;
mounting an IC die on the substrate;
electrically connecting the IC die to the plurality of contact pads;
sewing a first conductive thread into the substrate, wherein the first conductive thread has a proximal end and a distal end;
electrically connecting the proximal end of the first conductive thread to a corresponding one of the contact pads with a corresponding conductive bump; and
wherein the proximal end of the first conductive thread pierces the corresponding one of the contact pads.
18. The packaged IC device of claim 17 .