Method of electrochemically fabricating multilayer structures having improved interlayer adhesion

A fabrication process for forming a plurality of multi-layer three-dimensional structure, comprising:

• (a) providing a substrate;
• (b) forming and adhering a first multi-material layer to a substrate, wherein the first multi-material layer comprises a desired pattern of at least one structural metal and at least one sacrificial metal;
• (c) forming and adhering a subsequent multi-material layer to a previously formed layer, wherein the forming and adhering of the subsequent multi-material layer comprises
• a. selectively depositing at least one first metal using an adhered photoresist mask and thereafter removing the mask;
• b. depositing at least one second metal after removal of the mask;
• and
• c. planarizing the at least one first metal and the at least one second metal of the subsequent multi-material layer to set a boundary level for the subsequent multi-material layer, wherein the at least one first metal and the at least one second metal comprise at least one structural material and at least one sacrificial material;
• (d) repeating the forming and adhering operations of (b) and (c) at least once to build up a plurality of three-dimensional structures from a plurality of adhered multi-material layers;
• (e) after the forming of the plurality of adhered layers, releasing the plurality of three-dimensional structures from the at least one sacrificial material;
• (f) after formation of at least a plurality of layers, subjecting the multi-layer structure to a heat treatment, wherein a maximum effective temperature during heat treatment is less than a recrystallization temperature of a selected one of the at least one structural material and is in the range of 150° C.-350° C. and wherein the heat treatment is applied for a sufficient time, at a sufficient temperature, and in an environment that results in the formation of a structure which behaves monolithically up to at least the yield strength of the intra-layer material after heat treatment.

A fabrication process for forming a plurality of multi-layer three-dimensional structures, comprising:

• (a) providing a substrate;
• (b) forming and adhering a first multi-material layer to a substrate, wherein the first multi-material layer comprises a desired pattern of at least one structural metal and at least one sacrificial metal;
• (c) forming and adhering a subsequent multi-material layer to a previously formed layer, wherein the forming and adhering of the subsequent multi-material layer comprises:
• a. selectively depositing at least one first metal using an adhered photoresist mask and thereafter removing the mask;
• b. depositing at least one second metal after removal of the mask;
• and
• c. planarizing the at least one first metal and the at least one second metal of the subsequent multi-material layer to set a boundary level for the subsequent multi-material layer, wherein the at least one first metal and the at least one second metal comprise at least one structural material and at least one sacrificial material;
• (d) repeating the forming and adhering operations of (b) and (c) at least once to build up a plurality of three-dimensional structures from a plurality of adhered multi-material layers;
• (e) after the forming of the plurality of adhered layers, releasing the plurality of three-dimensional structures from the at least one sacrificial material;
• (f) after formation of the plurality of layers, subjecting the multi-layer structure to a heat treatment wherein a maximum effective temperature during heat treatment is less than a recrystallization temperature of a selected one of the at least one structural material and is in the range of 150° C.-350° C. and wherein the heat treatment is applied for a sufficient time, at a sufficient temperature, and in an environment that results in improved inter-layer adhesion after heat treatment such that the plurality of three-dimensional structures are no more likely to experience interlayer adhesion failure than intra-layer cohesion failure through an elastic deformation range of the structures (i.e. up to the beginning of the plastic deformation range of the structures) when under tension.

A fabrication process for forming a plurality of multi-layer three-dimensional structures, comprising:

• (a) providing a substrate;
• (b) forming and adhering a first multi-material layer to a substrate, wherein the first multi-material layer comprises a desired pattern of at least one structural metal and at least one sacrificial metal;
• (c) forming and adhering a subsequent multi-material layer to a previously formed layer, wherein the forming and adhering of the subsequent multi-material layer comprises:
• a. selectively depositing at least one first metal using an adhered photoresist mask and thereafter removing the mask;
• b. depositing at least one second metal after removal of the mask;
• and
• c. planarizing the at least one first metal and the at least one second metal of the subsequent multi-material layer to set a boundary level for the subsequent multi-material layer, wherein the at least one first metal and the at least one second metal comprise at least one structural material and at least one sacrificial material;
• (d) repeating the forming and adhering operations of (b) and (c) at least once to build up a plurality of three-dimensional structures from a plurality of adhered multi-material layers;
• (e) after the forming of the plurality of adhered layers, releasing the plurality of three-dimensional structures from the at least one sacrificial material;
• (f) after formation of the plurality of layers, subjecting the multi-layer structure to a heat treatment,
• wherein a maximum effective temperature during heat treatment is less than a recrystallization temperature of a selected one of the at least one structural material and is in the range of 150° C.-350° C.,
• wherein a post heat treatment intra-layer yield strength of the selected one of the at least one structural material is no less than 50% of a pre-heat treatment intra-layer yield strength of the selected one of the at least one structural material, and
• wherein the heat treatment is applied for a sufficient time, at a sufficient temperature, and in an environment that results in improved inter-layer adhesion after heat treatment such that the plurality of three-dimensional structures experience a reduced percentage of failures in inter-layer adhesion through an elastic deformation range of the structures (i.e. up to the beginning of the plastic deformation range of the structures) than would be present in absence of the heat treatment.