Temperature monitoring system

• US 20050254551A1
• Filed: 05/11/2004
• Published: 11/17/2005
• Est. Priority Date: 05/11/2004
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: McClure, Linden H., Gore, Makarand P., Ward, Shane R., Jedrzejewski, Mark J.
• Granted Patent: US 7,513,682 B2
• Time in Patent Office: Days
• US Class Current: 374/162
• CPC Class Codes: G01K 11/12 using changes in colour, translucency or reflectance
• CPC Class Codes: H05K 1/0201 Thermal arrangements, e.g. for cooling, heating or preventing overheating
• CPC Class Codes: H05K 1/0269 for visual or optical inspection
• CPC Class Codes: H05K 2203/161 Using chemical substances, e.g. colored or fluorescent, for facilitating optical or visual inspection
• CPC Class Codes: H05K 2203/163 Monitoring a manufacturing process
• CPC Class Codes: Y10S 252/962 Temperature or thermal history

Abstract

Disclosed herein is a temperature monitoring system including a circuit board and a thermochromic coating covering at least a portion of the circuit board, wherein the thermochromic coating is capable of indicating a temperature gradient on the circuit board. The thermochromic coating may comprise a color forming leuco dye, an activator, and optionally a deprotecting agent.

Claims

1. A system comprising:

a circuit board; and

a thermochromic coating covering at least a portion of the circuit board,

wherein the thermochromic coating indicates areas of increased

temperature on the circuit board; and

wherein the thermochromic coating comprises

a color forming leuco dye; and

an activator having at least one acid group.

2. The system of claim 1 wherein the activator comprises at least one functional group selected from the group consisting of hydroxyl, thio, and amine groups, and wherein the at least one functional group acts as a Lewis acid.

3. The system of claim 1 wherein the activator is selected from the group consisting of phenols, carboxylic acids, cyclic sulfonamides, protonic acids, and mixtures thereof.

4. The system of claim 1 wherein at least one of the acid group is protected by a protection leaving group to form a protected activator and further comprising a deprotecting agent configured to remove the protection leaving group from the activator upon application of energy.

5. The system of claim 4 wherein the protected activator is selected from the group consisting of esters, sulfonates, ethers, phosphinates, carbonates, carbamates, and mixtures thereof.

6. The system of claim 4 wherein the protection leaving group is an acyl selected from the group consisting of formate, acetate, levulinate, pivaolate, and mixtures thereof.

7. The system of claim 4 wherein the deprotecting agent is selected from the group consisting of valoneol, prolinol, 2-hydroxy-1-amino-propanol, 2-amino-3-phenyl-1-propanol, (R)-(−

)-2-phenyl glycinol, 2-amino-phenylethanol, 1-naphthylethyl amine, 1-aminonaphthalene, morpholin, and mixtures thereof.

8. The system of claim 1 wherein the color forming leuco dye is selected from the group consisting of fluorans, phthalides, aminotriarylmethanes, and mixtures thereof.

9. The system of claim 1 wherein the thermochromic coating is encapsulated.

10. The system of claim 1 wherein the thermochromic coating indicates a first area of increased temperature with a first color and indicates a second area of increase temperature with a second color.

11. The system of claim 1 where the thermochromic coating is a matrix and the activator and the leuco dye are substantially uniformly distributed in the matrix in separate phases.

12. A method comprising:

applying a coating to a substrate, the coating comprising

a color forming leuco dye; and

an activator having at least one acid group;

operating electrical devices mounted on the substrate; and

identifying areas of increased thermal activity based on color changes of the coating.

13. The method of claim 12 wherein activator comprises at least one functional group selected from the group consisting of hydroxyl, thio, and amine groups, and wherein the at least one functional group acts as a Lewis acid.

14. The method of claim 12 wherein the activator is a member selected from the group consisting of phenols, carboxylic acids, cyclic sulfonamides, protonic acids, and mixtures thereof.

15. The method of claim 12 wherein the activator is protected by a protection leaving group to form a protected activator and wherein the coating further comprises a deprotecting agent configured to remove the protection leaving group from the activator upon application of energy.

16. The method claim 15 wherein the protected activator is a member selected from the group consisting of esters, sulfonates, ethers, phosphinates, carbonates, carbamates, and mixtures thereof.

17. The method of claim 15 further comprising applying the coating wherein the protection leaving group is an acyl selected from the group consisting of formate, acetate, levulinate, pivaolate, and mixtures thereof.

18. The method of claim 15 further comprising applying the coating wherein the deprotecting agent is a member selected from the group consisting of valoneol, prolinol, 2-hydroxy-1-amino-propanol, 2-amino-3-phenyl-1-propanol, (R)-(−

)-2-phenyl glycinol, 2-amino-phenylethanol, 1-naphthylethyl amine, 1-aminonaphthalene, morpholin, and mixtures thereof.

19. The method of claim 12 wherein the color forming leuco dye is selected from the group consisting of fluorans, phthalides, aminotriarylmethanes, and mixtures thereof.

20. The method of claim 12 wherein identifying areas of increased thermal activity further comprises identifying color change of the coating resulting from the coating undergoing a phase change in response to heat from the circuit board.

21. The method of claim 12 wherein the leuco dye and the activator are substantially uniformly distributed in a matrix in separate phases.

22. The method of claim 12 wherein one of the leuco dye and the activator is dissolved in the matrix.

23. A system comprising:

a means for holding and interconnecting a plurality of electronic devices;

a means for indicating areas of increased temperature with color change on the means for holding.

24. The system of claim 23 wherein the means for indicating comprises an encapsulated dye or activator.

25. The system of claim 23 wherein the means for indicating indicates a first area of increased temperature having a first temperature with a first color, and indicates a second area of increase temperature having a second temperature higher than the first temperature with a second color.

26. The system of claim 23 where the means for indicating comprises a leuco dye and an activator substantially uniformly distributed in a matrix in separate phases.

27. The system of claim 23 wherein the means for indicating comprises a means for changing color, a means for activating a color change and a means for holding the means for changing and the means for activating in separate phases.

28. A circuit board comprising:

a substrate;

a plurality of electrical components mounted on the substrate; and

a thermochromic coating on the substrate, wherein the thermochromic coating comprises a color forming leuco dye and an activator having at least one acid group.

29. The circuit board of claim 28 wherein at least one of the acid groups is protected by a protection leaving group to form a protected activator and further comprising a deprotecting agent configured to remove the protection leaving group from the activator upon application of energy.

30. The circuit board of claim 28 where the thermochromic coating is a matrix and the activator and the leuco dye are substantially uniformly distributed in the matrix in separate phases.