# US 9,518,309 B2 · Method of manufacturing porous metal foam

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- Number: US 9,518,309 B2
- Document ID: US9518309B2
- Status: Granted
- Kind: B2
- Application number: 13/731,498
- Filed: 2012-12-31
- Published: 2014-07-03
- Granted: 2016-12-13
- Earliest claimed: 2012-12-31
- Assignees: Kookmin University Industry Academy Cooperation Foundation
- Applicants: Kookmin University Industry Academy Cooperation Foundation
- Inventors: Myoung-Geun Choi; Hyun-Gyung Jo; Hye-Ji Park; Yoon-Sook Noh; Yun-Sung Kim; Chang-Ui Ahn; Seok-Woo Jeon; Dong-Seok Kim; Do-Kyung Kim; Hee-Man Choe
- Web page: https://patentgrep.com/patent/US9518309B2

## CPC

- C22C 1/08: Alloys with open or closed pores
- C08J 9/365: {Coating}
- C23C 18/1639: {Substrates other than metallic, e.g. inorganic or organic or non-conductive}
- C23C 18/1644: {porous substrates}
- C23C 18/1657: {Electroless forming, i.e. substrate removed or destroyed at the end of the process}
- C23C 18/2006: {by other methods than those of C23C18/22 - C23C18/30}
- C23C 18/204: {Radiation, e.g. UV, laser}
- C23C 18/2086: {with use of organic or inorganic compounds other than metals, first}
- C23C 18/285: {Sensitising or activating with tin based compound or composition}
- C23C 18/30: Activating {or accelerating or sensitising with palladium or other noble metal}
- C23C 18/36: using hypophosphites
- C23C 18/405: {Formaldehyde}
- C08J 2201/038: Use of an inorganic compound to impregnate, bind or coat a foam, e.g. waterglass
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

A method of manufacturing a porous metal foam having pores of nano size includes: manufacturing a porous polymer foam containing pores of nano size; and coating metal on the porous polymer foam through electroless plating. The present invention provides porous metal foams which contains nano-sized pores and hence, their specific surface area is maximized owing to the regularly-patterned nanoporous structure formed inside.

## Claims

### Claim 1

A method of manufacturing a porous metal foam having pores of nano size, the method comprising the steps of:
manufacturing a porous polymer foam containing pores of nano size; and
coating metal on the porous polymer foam through electroless plating,
wherein the manufacturing a porous polymer foam includes:
positioning a cured elastomer having a pattern thereon on a polymer material; and
irradiating ultraviolet (UV) light to the polymer material through the cured elastomer to form the polymer foam containing pores of nano size using diffraction and interference of light.

### Claim 2 (depends on 1)

The method as claimed in claim 1, further comprising the step of: removing the porous polymer foam after the coating step.

### Claim 3 (depends on 1)

The method of claim 1, further comprising forming the cured elastomer, including:
casting an elastomer on a wafer having the pattern;
curing the cast elastomer; and
separating the cured elastomer from the wafer.

### Claim 4 (depends on 1)

The method of claim 1, further comprising etching a surface of the manufactured porous polymer with KMnO4 and H2SO4 to improve surface roughness of the porous polymer and activate the surface of the porous polymer.

### Claim 5 (depends on 1)

The method of claim 1, wherein the coating includes:
processing the surface of the porous polymer with a tin chloride (SnCl2.H2O) and hydrochloric acid (HCl) solution, or a palladium chloride (PdCl2) and hydrochloric acid (HCl) solution to attach Sn2+ or Pd2+ to the activated surface; and
immersing the polymer foam in a nickel or copper plating liquid.

### Claim 6 (depends on 5)

The method as claimed in claim 5, wherein the polymer foam is processed in the nickel plating liquid, a pH of which ranges from pH 4 to 5.

### Claim 7 (depends on 5)

The method as claimed in claim 5, wherein the polymer foam is processed in the copper plating liquid, a pH of which ranges from pH 11 to 12.

### Claim 8

A method of manufacturing a porous metal foam having pores of nano size, the method comprising the steps of:
(a) casting an elastomer on a silicon wafer having a pattern;
(b) curing the cast elastomer;
(c) separating the cured elastomer;
(d) attaching a polymer material on a glass substrate;
(e) positioning the elastomer on the polymer material;
(f) irradiating ultraviolet (UV) light to the material of the step (e) to form a polymer foam containing pores of nano size using diffraction and interference of light;
(g) pre-processing the polymer foam of the step (f) to improve surface wettability of the polymer foam; and
(h) coating metal on the pre-processed polymer foam through electroless plating.

### Claim 9 (depends on 8)

The method as claimed in claim 8, further comprising the step of: removing the polymer foam after the step (h).

### Claim 10 (depends on 8)

The method as claimed in claim 8, wherein the step (a) comprises:
(a-1) coating a photoresist material on the silicon wafer by a uniform thickness;
(a-2) attaching a photomask for forming the pattern on the photoresist material;
(a-3) irradiating UV light onto the photomask to soften the photoresist material; and
(a-4) etching the softened photoresist material to form the pattern on the silicon wafer.

### Claim 11 (depends on 8)

The method as claimed in claim 8, wherein the pre-processing of the step (g) is performed through O2 plasma or UV cleaner processing.

### Claim 12 (depends on 8)

The method as claimed in claim 8, wherein the pre-processing of the step (g) is performed with an ammonium hydroxide solution.

### Claim 13 (depends on 8)

The method as claimed in claim 8, wherein the metal coated through electroless plating in the step (h) is nickel or copper.

### Claim 14 (depends on 13)

The method as claimed in claim 13, wherein the coating of step (h) through electroless plating comprises the steps of:
etching a surface with KMnO4 and H2SO4 to improve surface roughness and activate the surface;
processing the surface with a tin chloride (SnCl2.H2O) and hydrochloric acid (HCl) solution, or a palladium chloride (PdCl2) and hydrochloric acid (HCl) solution to attach Sn2+ or Pd2+ to the activated surface; and
immersing the polymer foam in a nickel or copper plating liquid.

### Claim 15 (depends on 14)

The method as claimed in claim 14, wherein the polymer foam is processed in the nickel plating liquid, a pH of which ranges from pH 4 to 5.

### Claim 16 (depends on 14)

The method as claimed in claim 14, wherein the polymer foam is processed in the copper plating liquid, a pH of which ranges from pH 11 to 12.