Methods to Reduce Case Height for Capacitors
A method for forming a high aspect ratio sintered powder anode with low warpage, an anode made thereby and a cathode comprising the anode are provided. The method comprises placing a multiplicity of anode precursors on a forming substrate in a common plane wherein no more than 10% of the anode precursors are out of the common plane. A second substrate is then placed over the forming substrate with the anode precursors between the forming substrate and the second substrate thereby forming a sandwiched assembly. The sandwiched assembly is heated to a sintering temperature of the anode precursors thereby forming the sintered powder anodes. The and sintered powder anodes are removed from between the forming substrate and the second substrate.
1 . A method for forming a high aspect ratio sintered powder anodes with low warpage comprising:
placing a multiplicity of anode precursors on a forming substrate in a common plane wherein no more than 10% of said anode precursors are out of said common plane;
placing a second substrate over said forming substrate with said anode precursors between said forming substrate and said second substrate thereby forming a sandwiched assembly;
heating said sandwiched assembly to a sintering temperature of said anode precursors thereby forming said sintered powder anodes; and
removing said sintered powder anodes from between said forming substrate and said second substrate.
2 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein said sandwiched assembly is selected from an engaged sandwich and a separated sandwich.
3 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein said sintered powder anodes have an aspect ratio of at least 10.
4 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 3 wherein said sintered powder anodes have an aspect ratio of at least 20.
5 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein said sintered powder anodes have a warpage of no more than 20% relative to the sintered powder anodes thickness.
6 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 5 wherein said sintered powder anodes have a warpage of no more than 10% relative to the sintered powder anodes thickness. The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 further comprising placing an anode wire in at least one anode precursor of said anode precursors prior to said heating.
8 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 7 wherein said anode wire comprises voids.
9 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 further comprising electrically attaching an anode wire to said sintered powder anodes after at least some said heating.
10 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein at least one of said forming substrate or said second substrate comprises voids.
11 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein said forming substrate or said second substrate comprises at least one anode cavity.
12 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 11 wherein said forming substrate or said second substrate comprises at least one anode wire cavity.
13 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein said anode precursors comprise a material selected from the group consisting of Al, W, Ta, Nb, Ti, Zr, Hf and conductive oxides thereof.
14 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 13 wherein said anode precursors comprise a material selected from the group consisting of Al, Nb, Ta and NbO.
15 . The method for forming a high aspect ratio sintered powder anode with low warpage of claim 1 wherein said sintering is at a temperature of 1,000° C. to less than 1,500° C.
16 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein at least one of said second substrate or said forming substrate comprises a material selected from the group consisting of MgO, Al 2 O 3 , Ta, TaN, Ta 2 O 5 and TaO.
17 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 further comprising dicing at least one sintered powder anode.
18 . The method for forming a high aspect ratio sintered powder anodes with low warpage of claim 1 wherein said sintering temperature is 1,000° C. to less than 1,500° C.
19 . A method for forming a capacitor comprising:
forming a high aspect ratio sintered powder anode with low warpage by:
placing a multiplicity of anode precursors on a forming substrate;
placing a second substrate over said forming substrate with said anode precursors between said forming substrate and said weighted substrate thereby forming a sandwiched assembly;
heating said sandwiched assembly to a sintering temperature of said anode precursors thereby forming at least one said sintered powder anode; and
removing said sintered powder anode from between said forming substrate and said second substrate;
forming a dielectric on said sintered powder anode; and
forming a cathode on said dielectric.
20 . The method for forming a capacitor of claim 19 wherein said sintered powder anode has an aspect ratio of at least 10.
21 . The method for forming a capacitor of claim 20 wherein said sintered powder anode has an aspect ratio of at least 20.
22 . The method for forming a capacitor of claim 19 wherein said sintered powder anode has an warpage of no more than 20% relative to the sintered powder anode thickness.
23 . The method for forming a capacitor of claim 22 wherein said sintered powder anode has an warpage of no more than 10% relative to the sintered powder anode thickness.
24 . The method for forming a capacitor of claim 19 further comprising placing an anode wire in said anode precursor prior to said heating.
25 . The method for forming a capacitor of claim 24 wherein said anode wire comprises voids.
26 . The method for forming a capacitor of claim 19 further comprising electrically attaching an anode wire to said sintered powder anode after at least some said heating.
27 . The method for forming a capacitor of claim 19 wherein at least one of said forming substrate or said second substrate comprises voids.
28 . The method for forming a capacitor of claim 19 wherein said forming substrate or said second substrate comprises at least one anode cavity.
29 . The method for forming a capacitor of claim 19 wherein said forming substrate or said second substrate comprises at least one anode wire cavity.
30 . The method for forming a capacitor of claim 19 wherein said anode precursors comprise a material selected from the group consisting of Al, W, Ta, Nb, Ti, Zr, Hf and conductive oxides thereof.
31 . The method for forming a capacitor of claim 30 wherein said anode precursors comprise a material selected from the group consisting of Al, Nb, Ta and NbO.
32 . The method for forming a capacitor of claim 19 wherein said sintering is at a temperature of 1,000° C. to less than 1,500 ° C.
33 . The method for forming a capacitor of claim 19 wherein at least one of said second substrate or said forming substrate comprises a material selected from the group consisting of MgO, Al 2 O 3 , Ta, TaN, Ta 2 O 5 and TaO.
34 . The method for forming a capacitor of claim 19 wherein said cathode comprises a material selected from manganese dioxide and a conductive polymer.
35 . The method for forming a capacitor of claim 34 wherein said conductive polymer comprises a thiophene.
36 . The method for forming a capacitor of claim 35 wherein said thiophene is polymerized 3,4-polyethylene dioxythiophene.
37 . The method for forming a capacitor of claim 19 wherein said sintering temperature is 1,000° C. to less than 1,500° C.
38 . The method for forming a capacitor of claim 19 further comprising dicing at least one said sintered powder anode.
39 . A capacitor comprising:
a sintered powder anode having an aspect ratio of at least 10 and a warpage of no more than 20%;
an anode wire in electrical contact with said sintered powder anode;
a dielectric on said sintered powder anode; and
a cathode on said dielectric.
40 . The capacitor of claim 39 wherein said aspect ratio is at least 20.
41 . The capacitor of claim 39 wherein said sintered powder anode has an warpage of no more than 20% relative to the anode thickness.
42 . The capacitor of claim 39 wherein said anode wire comprises voids.
43 . The capacitor of claim 39 wherein said sintered powder anode comprises a material selected from the group consisting of Al, W, Ta, Nb, Ti, Zr, Hf and conductive oxides thereof.
44 . The capacitor of claim 43 wherein said sintered powder anode comprises a material selected from the group consisting of Al, Nb, Ta and NbO.