Composition of a solder, and method of manufacturing a solder connection
View Patent ↗The solder composition comprises particles of a thermodynamically metastable alloy. One of the elements of the alloy will form an intermetallic compound with a metal surface. The solder composition is particularly suitable for use in bumping of semiconductor devices.
1. A composition of a solder in which particles of a thermodynamically metastable alloy are dispersed, which alloy comprises an element that, upon application of the composition to a solderable metal oxide containing surface, form an intermetallic compound with the metal of said surface,
wherein said intermetallic compound comprises both an alloying element of the solderable metal oxide containing surface and an element originating from the thermodynamically metastable particles, and
wherein said particles of the thermodynamically metastable alloy are primarily constituted from a two-phase mixture of compounds comprising a first and a second component including a first shell of the thermodynamically metastable alloy in a first phase that is not thermodynamically metastable, and a second shell of the thermodynamically metastable alloy in a second phase that is thermodynamically metastable,
wherein upon application of the solder composition to the solderable metal oxide containing surface, constituents of the metastable particles react with the solderable metal oxide containing surface to form said intermetallic compound and wet the surface to remove an oxide surface layer of the solderable metal oxide containing surface and replace the oxide surface layer with an electrically conductive adhesion layer of the intermetallic compound.
2. Composition as claimed in claim 1 , wherein the element of the alloy that reacts with the surface is chosen from the group of Sn, Zn, In, Al and Bi.
3. Composition as claimed in claim 2 , wherein the reacting element is Sn and the solder composition comprises Sn.
4. Composition as claimed in claim 1 , in which the dispersed particles are present in a weight concentration of 0.1 to 90%.
5. Composition as claimed in claim 1 , in which the dispersed particles have an average diameter between 0.5 and 80 μm.
6. A substrate with a bonding area on which a layer of a solder composition as claimed in claim 1 .
7. A substrate as claimed in claim 6 , wherein the layer of solder composition is droplet-shaped.
8. A substrate as claimed in claim 6 , wherein the substrate is part of an integrated circuit.
9. Composition as claimed in claim 1 , in which the dispersed particles are present in a weight concentration of 0.5 to 60%.
10. Composition as claimed in claim 1 , in which the dispersed particles have an average diameter between 1 and 20 μm.