Sintering powder
A sintering powder comprising: a particulate having a mean longest diameter of less than 10 microns, wherein at least some of the particles forming the particulate comprise a metal at least partially coated with a capping agent. A sintering paste and sintering film comprising the sintering powder. A method for making a sintered joint by sintering the sintering powder, paste, or film in the vicinity of two or more workpieces.
1 . A sintering film comprising a sintering powder and a binder, wherein the sintering powder comprises:
a particulate comprising heterogeneous particles having a mean longest diameter of less than 10 microns, wherein at least some of the particles forming the particulate comprise a metal at least partially coated with a capping agent,
wherein the particulate comprises a first type of particles having a longest diameter of from 1 to 100 nm and a second type of particles having a longest diameter of from greater than 100 nm to 50 microns,
wherein the particulate comprises from 81 to 99 wt % of the first type of particles and from 1 to 19 wt % of the second type of particles; and
wherein the sintering film further comprises an organosilver compound in a concentration of 1-25 wt %.
2 . The sintering film of claim 1 wherein the capping agent comprises an amine and/or a carboxylate functional group.
3 . The sintering film of claim 2 wherein the capping agent comprises a straight chain or branched chain aliphatic amine.
4 . The sintering film of claim 2 wherein the metal comprises one or more metals selected from silver, copper, nickel, molybdenum, tungsten, and alloys and mixtures thereof.
5 . The sintering film of claim 2 comprising from 0.1 to 3 wt % capping agent.
6 . The sintering film of claim 1 , wherein the first type of particles have a diameter of from 5 to 75 nm and/or the second type of particles have a diameter of from greater than 100 nm to 20 microns.
7 . The sintering film of claim 5 , wherein the particulate has a mean longest diameter of from 1 to 100 nm.
8 . The sintering film of claim 5 , wherein the particulate has a mean longest diameter of from 100 nm to 10 microns.
9 . The sintering film of claim 1 , wherein the sintering powder is manufactured by a method comprising the steps:
providing a metal salt solution;
contacting the metal salt solution with a capping agent; and
precipitating metal particles at least partially coated with the capping agent.
10 . The sintering film of claim 9 , wherein the precipitating step is carried out using a reducing agent.
11 . The sintering film of claim 9 , wherein the reducing agent comprises hydrazine and/or sodium borohydride.
12 . The sintering film of claim 1 , wherein the organosilver compound comprises one or more of silver oxalate, silver lactate, silver succinate, silver neodecanoate, silver citrate and silver stearate.
13 . The sintering film of claim 1 , comprising 2-10 wt % of the organosilver compound.
14 . The sintering film of claim 1 , wherein the organosilver compound comprises silver oxalate.
15 . The sintering film of claim 1 , wherein the organosilver compound comprises silver lactate.
16 . The sintering film of claim 13 , wherein the organosilver compound comprises silver oxalate.
17 . A method of manufacturing a sintered joint comprising the steps:
providing the sintering film of claim 1 in the vicinity of two or more work pieces to be joined; and
heating the sintering film to at least partially sinter the metal.
18 . The method of claim 17 wherein the heating is carried out at a temperature of at least 140° C.
19 . The method of claim 17 wherein the heating is carried out at a temperature of from 150° C. to 300° C.
20 . The method of claim 17 wherein the heating is carried out at a temperature of from 160°° C. to 300° C.
21 . The method of claim 17 wherein the heating is carried out at atmospheric pressure.
22 . The method of claim 17 wherein the heating is carried out under an applied pressure of from 1 to 5 MPa.
23 . The method of claim 17 wherein the heating is carried out under an applied pressure of from 1 to 5 MPa for 0.1 to 60 seconds at a temperature of about 175 to 250° C.