A torch bump is provided, which is a solder bump comprising a base over which a solder bump is created. A first layer of dry film is over a supporting surface over which first a layer of UBM has been deposited. A base for the solder bump is created in a first opening through the first layer of dry film, the base aligns with an underlying contact pad. A second dry film is over the surface of the first dry film, a second opening is created through the second dry film that aligns with the created base of the solder bump. The opening through the second dry film is filled with solder by solder printing, the first and second layers of dry film are removed, the deposited layer of UBM is etched. Reflow is applied to the deposited solder, creating the torch solder bump.
1. A structure for a torch bump, comprising:
a substrate having been provided with a contact pad over the surface thereof;
layer of passivation over the surface of the substrate and exposing the surface of said contact pad;
a UBM over the surface of the layer of passivation including the exposed surface of the contact pad; and
a base of said torch bump overlying said contact pad and having a flat top area, said base having said torch bump bonded to the flat top area at a flat bottom area of said torch bump, said flat top area larger than the flat bottom area.
2. The structure of claim 1 , said base of said torch bump further comprising a first layer, a second layer on the first layer, and a third layer on the second layer.
3. The structure of claim 1 , said base of said torch bump further comprising:
a first layer of copper having been deposited over the exposed surface of said layer of UBM;
a second layer of nickel having been deposited over said first layer of copper; and
a third layer of gold having been deposited over the surface of said second layer of nickel.
4. The structure of claim 3 , said first layer of copper having been deposited to a thickness of about 90 μm.
5. The structure of claim 3 , said second layer of nickel being deposited to a thickness of about 5 μm.
6. The structure of claim 3 , said third layer of gold having been deposited to a thickness of about 5 μm.
7. The structure of claim 2 , wherein the top of the first layer is flat.
8. The structure of claim 1 , said base of said torch bump further comprising:
a first layer of solder having been deposited over the exposed surface of said layer of UBM; and
a second layer of eutectic solder paste having been deposited over said first layer of solder.
9. The structure of claim 8 , whereby additionally a layer of nickel having been deposited over the surface of said first layer of solder after which a layer of gold having been deposited over the surface of said layer of nickel after which said second layer of eutectic solder paste having been deposited over the surface of said layer of gold.
10. The structure of claim 1 , said layer of UBM comprising nickel.
11. The structure of claim 10 , said nickel having been deposited to a thickness between about 1 and 10 μm.
12. The structure of claim 1 , additionally said layer of UBM having been etched using said created base of said torch bump and said created layer of solder as a mask.
13. The structure of claim 2 , wherein the first layer, the second layer, and the third layer have flat top areas.
14. The structure of claim 1 , wherein the diameter of the base of said torch bump is larger than the diameter of the torch bump which is larger than the diameter of the flat bottom area.
15. The structure of claim 2 , wherein the third layer is flat.
16. The structure of claim 2 , wherein the third layer is gold.