Solderable top metalization and passivation for source mounted package
View Patent ↗A silver-containing solderable contact on a semiconductor die has its outer edge spaced from the confronting edge of an epoxy passivation layer so that, after soldering, silver ions are not present and are not therefor free to migrate under the epoxy layer to form dendrites.
1. A solderable contact for electrical connection to a semiconductor die;
said solderable contact comprising a silver-containing layer disposed atop a semiconductor die; and
a passivation layer formed on said die surface;
said passivation layer having a first layer and an underlying second layer;
said first passivation layer and said solderable contact having confronting edges which are spaced by a gap;
a width of said gap configured such that no silver is encapsulated under said first passivation layer and all of said silver is exposed to alloying during soldering, wherein said solderable contact is directly attached to an electrode of said semiconductor die.
2. The solderable contact of claim 1 , wherein said underlying second passivation layer is a nitride layer; said nitride layer extending across and under said gap and being overlapped by said edge of said solderable contact.
3. The device of claim 1 , wherein said first passivation layer is an epoxy layer.
4. The device of claim 2 , wherein said first passivation layer is an epoxy layer.
5. The device of claim 1 , wherein said solderable contact is a composite layer of titanium, nickel and silver.
6. The device of claim 2 , wherein said solderable contact is a composite layer of titanium, nickel and silver.
7. The device of claim 3 , wherein said solderable contact is a composite layer of titanium, nickel and silver.
8. The device of claim 4 , wherein said solderable contact is a composite layer of titanium, nickel and silver.
9. The device of claim 1 , wherein said gap has a width of from about 5 microns to about 20 microns.
10. The device of claim 2 , wherein said gap has a width of from about 5 microns to about 20 microns.
11. The device of claim 3 , wherein said gap has a width of from about 5 microns to about 20 microns.
12. The device of claim 5 , wherein said gap has a width of from about 5 microns to about 20 microns.
13. A solderable contact for electrical connection to a semiconductor die;
said solderable contact comprising a silver-containing layer disposed atop a semiconductor die; and
a passivation layer formed on said die surface;
said passivation layer having a first layer and an underlying second layer;
said first passivation layer and said solderable contact having confronting edges which are spaced by a gap having a width between 5 microns to 20 microns such that no silver is encapsulated under said first passivation layer and all of said silver is exposed to alloying during soldering, wherein said solderable contact is directly attached to an electrode of said semiconductor die.
14. The solderable contact of claim 13 , wherein said underlying second passivation layer is a nitride layer;
said nitride layer extending across and under said gap and being overlapped by said edge of said solderable contact.
15. The solderable contact of claim 13 , wherein said first passivation layer is an epoxy layer.
16. The solderable contact of claim 14 , wherein said first passivation layer is an epoxy layer.
17. The solderable contact of claim 13 , wherein said solderable contact is a composite layer of titanium, nickel and silver.
18. The solderable contact of claim 14 , wherein said solderable contact is a composite layer of titanium, nickel and silver.
19. The solderable contact of claim 15 , wherein said solderable contact is a composite layer of titanium, nickel and silver.
20. The solderable contact of claim 16 , wherein said solderable contact is a composite layer of titanium, nickel and silver.