Process for Forming Self-Assembled Monolayer on Metal Surface and Printed Circuit Board Comprising Self-Assembled Monolayer
The present invention provides a printed circuit board comprising a metal surface, such as a final finish, that has been coated with a self-assembled monolayer. The self-assembled monolayer forms a coating on the metal surface that is resistant to corrosion, thus preserving the solderability of the metal surface. The present invention also provides a solution of an alkanethiol and a non-organic solvent that can be used for forming a self-assembled monolayer on a metal substrate. The present invention also provides a process for depositing a self-assembled monolayer on a metal substrate by applying a solution of an alkanethiol and a non-organic solvent to a metal substrate, such as a surface of a printed circuit board.
1 . A printed circuit board comprising a metal surface coated with a self-assembled monolayer.
2 . The printed circuit board of claim 1 , wherein the self-assembled monolayer comprises an alkanethiol.
3 . The printed circuit board of claim 2 , wherein the alkanethiol is selected from the group consisting of hexanethiol, heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol, tridecanethiol, tetradecanethiol, pentadecanethiol, hexadecanethiol, heptadecanethiol, and octadecanethiol.
4 . The printed circuit board of claim 3 , wherein the alkanethiol is dodecanethiol.
5 . The printed circuit board of claim 1 , wherein the metal surface comprises nickel, gold, silver, palladium, copper, or combinations thereof.
6 . The printed circuit board of claim 1 , wherein the metal surface comprises a final finish.
7 . The printed circuit board of claim 6 , wherein the final finish is selected from the group consisting of Electroless Nickel, Electroless Palladium, Electroless Nickel/Immersion Gold (ENIG), Electroless Nickel/Electroless Palladium (ENEP), Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG), and Immersion Silver.
8 . A solution for forming a self-assembled monolayer on a metal substrate, comprising:
(a) an alkanethiol;
(b) a non-organic solvent; and
(c) a surfactant.
9 . The solution of claim 8 , wherein the alkanethiol is selected from the group consisting of hexanethiol, heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol, tridecanethiol, tetradecanethiol, pentadecanethiol, hexadecanethiol, heptadecanethiol, and octadecanethiol.
10 . The solution of claim 8 , wherein the non-organic solvent is water.
11 . The solution of claim 10 , wherein the alkanethiol is dodecanethiol and the surfactant is sodium dodecyl sulfate.
12 . The solution of claim 8 , further comprising a defoamer.
13 . A process for depositing a self-assembled monolayer on a metal substrate, comprising:
(a) providing the solution of claim 8 ; and
(b) applying the solution to a metal substrate.
14 . The process of claim 13 , wherein the solution is applied to the metal substrate by dipping, flooding, spraying, painting, or combinations thereof.
15 . The process of claim 14 , wherein the solution is applied to the metal substrate by dipping.
16 . The process of claim 15 , wherein the dipping is performed at a temperature between about 25 and about 35° C. and for a length of time between about one minute and about five minutes.
17 . The process of claim 13 , wherein the alkanethiol is selected from the group consisting of hexanethiol, heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol, tridecanethiol, tetradecanethiol, pentadecanethiol, hexadecanethiol, heptadecanethiol, and octadecanethiol.
18 . The process of claim 13 , wherein the non-organic solvent is water.
19 . The process of claim 18 , wherein the alkanethiol is dodecanethiol and the surfactant is sodium dodecyl sulfate.
20 . The process of claim 13 , wherein the metal substrate is a printed circuit board or a component of a printed circuit board.
21 . The self-assembled monolayer formed by the process of claim 13 .
22 . A method of preserving the solderability of a metal surface of a printed circuit board comprising forming a self-assembled monolayer on the metal surface.
23 . The method of claim 22 , wherein the self-assembled monolayer comprises an alkanethiol.
24 . The method of claim 22 , wherein the metal surface comprises a final finish.
25 . The method of claim 24 , wherein the final finish is selected from the group consisting of Electroless Nickel, Electroless Palladium, Electroless Nickel/Immersion Gold (ENIG), Electroless Nickel/Electroless Palladium (ENEP), Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG), and Immersion Silver.