Diode for use in testing semiconductor packages
Embodiments described herein provide techniques for testing a semiconductor package by using a diode to couple a test pad to a contact pad. In one scenario, a package comprises a die stack comprising one or more dies and a molding compound encapsulating the die stack. In this package, a substrate is over the molding compound. Also, a test pad and a contact pad are on a surface of the substrate. The contact pad is coupled to the die stack. A diode couples the test pad to the contact pad. In one example, the test pad is coupled to a P side of the diode's P-N junction and the contact pad is coupled to an N side of the diode's P-N junction. In operation, current can flow from the test pad through the contact pad (and the die stack), but current cannot flow from the contact pad through the test pad.
1. A semiconductor package, comprising:
a die stack comprising one or more dies;
a molding compound encapsulating the die stack;
a substrate over the molding compound;
a test pad on a surface of the substrate;
a contact pad on the surface of the substrate and electrically coupled to the die stack; and
a diode coupling the test pad to the contact pad, the diode comprising a P-N junction.
2. The semiconductor package of claim 1 , wherein the test pad is coupled to a P-side of the P-N junction of the diode and the contact pad is coupled to an N-side of the P-N junction of the diode.
3. The semiconductor package of claim 1 , wherein the test pad is coupled to an N-side of the P-N junction of the diode and the contact pad is coupled to a P-side of the P-N junction of the diode.
4. The semiconductor package of claim 1 , wherein the diode is embedded in the substrate.
5. The semiconductor package of claim 1 , wherein the diode is encapsulated by the molding compound.
6. The semiconductor package of claim 5 , wherein the diode is in contact with the die stack.
7. The semiconductor package of claim 5 , wherein the diode is adjacent to the die stack.
8. The semiconductor package of claim 1 , wherein the diode is a signal diode or a rectifier diode.
9. The semiconductor package of claim 1 , wherein the contact pad is a high speed input/output interface.
10. A packaged system, comprising:
a semiconductor package, comprising:
a die stack comprising a plurality of dies;
a molding compound encapsulating the die stack;
a redistribution layer over the molding compound;
a plurality of test pads on a surface of the redistribution layer;
a plurality of contact pads on the surface of the redistribution layer and electrically coupled to the die stack by a wire bond embedded in the molding compound; and
a plurality of diodes, each diode comprising a P-N junction, wherein a first terminal of each diode is electrically coupled to one of the contact pads by a conductive trace, and wherein a second terminal of each diode is electrically coupled to one of the test pads by a conductive trace; and
a printed circuit board, wherein the semiconductor package is electrically coupled to the printed circuit board by interconnects contacting the contact pads.
11. The packaged system of claim 10 , wherein the test pads are coupled to a P-side terminal of the P-N junction of the diode and the contact pads are coupled to an N-side terminal of the P-N junction of the diode.
12. The packaged system of claim 10 , wherein the test pads are coupled to an N-side of the P-N junction of the diode and the contact pads are coupled to a P-side of the P-N junction of the diode.
13. The packaged system of claim 10 , wherein the diodes are embedded in the redistribution layer.
14. The packaged system of claim 10 , wherein at least one of the diodes is a signal diode or a rectifier diode.
15. The packaged system of claim 10 , wherein at least one of the contact pads is a high speed input/output interface.
16. The packaged system of claim 10 , wherein the diodes are encapsulated by the molding compound.
17. The packaged system of claim 16 , wherein the diodes are in contact with the die stack.
18. The packaged system of claim 16 , wherein the diodes are adjacent to the die stack.