Pattern formation using electroless plating and articles
A conductive pattern can be formed using a polymeric layer that contains a reactive composition that comprises a reactive polymer that is metal ion-complexing, water-soluble, and crosslinkable. This reactive polymer comprises pendant groups comprising crosslinkable —C(═O)—CR═CR 1 —Y— groups wherein R and R 1 are defined in the disclosure, as well as metal ion-complexing and water solubilizing groups. The reactive composition can be patternwise exposed to suitable radiation to induce crosslinking within the reactive polymer. The reactive composition and reactive polymer in the non-exposed regions can be removed due to their aqueous solubility, but the exposed regions of the polymeric layer are contacted with electroless seed metal ions, which are then reduced. The resulting electroless seed metal nuclei are electrolessly plated with a suitable metal to form the desired conductive pattern. Various articles can be prepared during this process, and the product article can be incorporated into various electronic devices.
1. A method for forming a pattern in a polymeric layer, the method comprising:
providing a polymeric layer comprising a reactive composition that comprises: (1) a reactive polymer that is metal ion-complexing, water-soluble, and crosslinkable, which reactive polymer comprises a backbone, and arranged in any order along the backbone, —A—recurring units that comprise pendant groups comprising crosslinkable —C(═O)—CR═CR 1 —Y— groups wherein R and R 1 are independently hydrogen or an alkyl group having 1 to 7 carbon atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having 1 to 7 carbon atoms, a phenyl group, or a phenoxy group, and Y is a substituted or unsubstituted aryl or aromatic heterocyclic ring, in an amount of at least 2 mol %, and —B— recurring units comprising pendant metal ion-complexing and water-solubilizing groups in an amount of at least 50 mol %, both based on the total recurring units in the reactive polymer; and (2) optionally, a photosensitizer,
patternwise exposing the polymeric layer to radiation having a λ max of at least 150 nm that is sufficient to induce crosslinking within the reactive polymer, to provide a polymeric layer comprising non-exposed regions and exposed regions comprising an at least partially crosslinked polymer derived from the reactive polymer,
optionally heating the polymeric layer simultaneously with or after patternwise exposing the polymeric layer but before removing the reactive composition comprising the reactive polymer in the non-exposed regions, at a temperature sufficient to further crosslink the at least partially crosslinked polymer in the exposed regions of the polymeric layer,
removing the reactive composition comprising the reactive polymer in the non-exposed regions,
contacting the exposed regions of the polymeric layer with electroless seed metal ions to form a pattern of electroless seed metal ions in the exposed regions of the polymeric layer,
reducing the pattern of electroless seed metal ions to provide a pattern of corresponding electroless seed metal nuclei in the exposed regions of the polymeric layer, and
electrolessly plating the corresponding electroless seed metal nuclei in the exposed regions of the polymeric layer with a metal that is the same as or different from the corresponding electroless seed metal nuclei.
2. The method of claim 1 ,
wherein the —A— recurring units are present in an amount of at least 2 mol % and up to and including 50 mol %, and the —B— recurring units are present in an amount of at least 50 mol % and up to and including 98 mol %, both based on the total recurring units in the reactive polymer.
3. The method of claim 1 , wherein the —B— recurring units comprise pendant carboxylic acid, carboxylate, sulfonic acid, or sulfonate groups.
4. The method of claim 1 , wherein the reactive polymer comprises at least 10 mol % and up to and including 40 mol % of —A— recurring units comprising crosslinkable —C(═O)—CR—CR 1 -phenyl groups wherein R and R 1 are independent hydrogen, methyl, ethyl, or phenyl groups, based on the total recurring units in the reactive polymer, and at least 60 mol % and up to and including 90 mol % of —B— recurring units.
5. The method of claim 1 , wherein the reactive polymer further comprises one or more additional —C— recurring units that are different from all —A— and —B— recurring units, the one or more additional —C— recurring units being present in an amount of up to and including 20 mol % based on the total reactive polymer recurring units.
6. The method of claim 1 , wherein the reactive polymer comprises at least 50 weight % and up to 100 weight % of the total dry weight of the polymeric layer.
7. The method of claim 1 , wherein the reactive composition further comprises a photosensitizer in the polymeric layer in an amount of at least 0.1 weight % based on the total solids in the polymeric layer, which photosensitizer provides sensitization at a λ max of at least 150 nm and up to and including 700 nm.
8. The method of claim 1 , further comprising:
heating the polymeric layer after patternwise exposing the polymeric layer but before removing the reactive composition comprising the reactive polymer in the non-exposed regions, at a temperature sufficient to further crosslink the at least partially crosslinked polymer in the exposed regions of the polymeric layer.
9. The method of claim 1 , comprising contacting the exposed regions in the polymeric layer with electroless seed metal ions selected from the groups consisting of silver ions, platinum ions, palladium ions, gold ions, rhodium ions, nickel ions, iridium ions, tin ions, and copper ions.
10. The method of claim 1 , comprising electrolessly plating with a metal that is selected from the group consisting of copper(II), silver(I), gold(IV), palladium(II), platinum(II), nickel(II), chromium(II), and combinations thereof.
11. The method of claim 1 , comprising patternwise exposing the polymeric layer to radiation having a λ max of at least 150 nm and up to and including 450 nm.
12. The method of claim 1 , comprising reducing the electroless seed metal ions in the exposed regions of the polymeric layer with a reducing agent that is a borane, aldehyde, hydroquinone, or sugar reducing agent.
13. A precursor article used in the method of claim 1 , the precursor article comprising a substrate and having disposed thereon a polymeric layer comprising a reactive composition that comprises:
(1) a reactive polymer that is metal ion-complexing, water-soluble, and crosslinkable, which reactive polymer comprises a backbone, and arranged in any order along the backbone, —A— recurring units that comprise pendant groups comprising crosslinkable —C(═O)—CR═CR 1 —Y— groups wherein R and R 1 are independently hydrogen or an alkyl group having 1 to 6 carbon atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, or a phenoxy group, and Y is a substituted or unsubstituted aryl or aromatic heterocyclic ring, in an amount of at least 2 mol %; and —B— recurring units comprising pendant metal ion-complexing and water-solubilizing groups in an amount of at least 50 mol %, both based on the total recurring units in the reactive polymer, and (2) optionally, a photosensitizer.
14. The precursor article of claim 13 ,
wherein the —A— recurring units are present in an amount of at least 2 mol % and up to and including 50 mol %, and the —B— recurring units are present in an amount of at least 50 mol % and up to and including 98 mol %, both based on the total recurring units in the reactive polymer.
15. The precursor article of claim 13 , wherein the —B— recurring units comprise pendant carboxylic acid, carboxylate, sulfonic acid, or sulfonate groups.
16. The precursor article of claim 13 , wherein the reactive polymer comprises at least 10 mol % and up to and including 40 mol % of —A— recurring units comprising crosslinkable —C(═O)—CR═CR 1 -phenyl groups wherein R and R 1 are independent hydrogen, methyl, ethyl, or phenyl groups, based on the total recurring units in the reactive polymer, and at least 60 mol % and up to and including 90 mol % of —B— recurring units.
17. The precursor article of claim 13 , wherein the reactive polymer further comprises one or more additional —C— recurring units that are different from all —A— and —B— recurring units, the one or more additional —C— recurring units being present in an amount of up to and including 20 mol % based on the total reactive polymer recurring units.
18. The precursor article of claim 13 , wherein the reactive composition further comprises a photosensitizer in the polymeric layer in an amount of at least 0.1 weight % based on the total solids in the polymeric layer, which photosensitizer provides sensitization at a λ max of at least 150 nm and up to and including 700 nm.
19. A product article prepared by the method of claim 1 , the product article comprising a substrate and having disposed thereon a polymeric layer comprising exposed regions and non-exposed regions,
the exposed regions comprising a pattern of electrolessly plated metal complexed within or deposited on the surface of an at least partially crosslinked polymer that has been derived from a reactive polymer that is metal ion-complexing, water-soluble, and crosslinkable, which reactive polymer comprises a backbone, and arranged in any order along the backbone, —A— recurring units that comprise pendant groups comprising crosslinkable —C(═O)—CR═CR 1 —Y— groups wherein R and R 1 are independently hydrogen or an alkyl group having 1 to 7 carbon atoms, a 5- to 6-membered cycloalkyl group, an alkoxy group having 1 to 7 carbon atoms, a phenyl group, or a phenoxy group, and Y is a substituted or unsubstituted aryl or aromatic heterocyclic ring, in an amount of at least 2 mol %, and —B— recurring units comprising pendant metal ion-complexing and water-solubilizing groups in an amount of at least 50 mol %, both based on the total recurring units in the reactive polymer, and
the non-exposed regions comprising none of the electrolessly plated metal or the reactive polymer that is metal ion-complexing, water-soluble, and crosslinkable.