Sintering materials and attachment methods using same
Methods for die attachment of multichip and single components may involve printing a sintering paste on a substrate or on the back side of a die. Printing may involve stencil printing, screen printing, or a dispensing process. Paste may be printed on the back side of an entire wafer prior to dicing, or on the back side of an individual die. Sintering films may also be fabricated and transferred to a wafer, die or substrate. A post-sintering step may increase throughput.
1. A sheet of sintering film, comprising:
a substrate;
a release coating disposed on the substrate; and
a layer of a dry sintering material having a thickness of about 5 to about 300 microns disposed on the release coating on the substrate;
wherein the sintering material comprises, prior to drying:
(i) a metal powder having a d 50 range of about 0.001 to about 10 micrometers, the metal powder comprising about 30 to about 95 wt % of the sintering material;
(ii) a binder having a softening point between about 50 and about 170° C., the binder comprising about 0.1 to about 5 wt % of the sintering material; and
(iii) a solvent in an amount sufficient to dissolve at least the binder;
wherein the substrate is configured to be removed during a lamination process; and
wherein the layer of sintering material is applied in discrete shapes with respect to a surface of the substrate, and the discrete shapes have geometries corresponding to dimensions of a component to be attached using the layer of sintering material.
2. The sheet of sintering film of claim 1 , wherein the substrate is a polymeric, glass, metal, or ceramic substrate.
3. The sheet of sintering film of claim 1 , wherein the sintering material further comprises one or more functional additives.
4. The sheet of sintering film of claim 3 , wherein the one or more functional additives comprise chlorinated diols and/or metallorganic compounds.
5. The sheet of sintering film of claim 1 , wherein the metal powder comprises gold, palladium, silver, copper, aluminum, silver palladium alloy, or gold palladium alloy.
6. The sheet of sintering film of claim 5 , wherein the metal powder comprises silver particles.
7. The sheet of sintering film of claim 5 , wherein the metal powder comprises nanoparticles.
8. The sheet of sintering film of claim 5 , wherein the metal powder comprises coated metal particles.
9. The sheet of sintering film of claim 1 , configured to provide a bond line characterized by a thermal conductivity of about 250 W/m° K.
10. The sheet of sintering film of claim 1 , configured to provide a bond line characterized by a bond strength of at least about 40 MPa.
11. The sheet of sintering film of claim 1 , configured for a sintering operation at a temperature of about 175° C. to about 400° C.
12. The sheet of sintering film of claim 11 , configured for a sintering operation at a temperature of about 230° C. to about 260° C.
13. The sheet of sintering film of claim 1 , configured for a sintering operation at a pressure of between about 0.5 MPa and 20 MPa.
14. The sheet of sintering film of claim 13 , configured for a sintering operation at a pressure of between about 5 MPa and 10 MPa.
15. The sheet of sintering film of claim 1 , configured to provide a bond line having a thickness in a range of about 2 microns to about 100 microns.
16. The sheet of sintering film of claim 1 , wherein the discrete shapes are constructed and arranged to facilitate tape-and-reel dispensing of the film during an assembly operation.