Thermocouple ribbon and assembly
A thermocouple ribbon features a pair of flat conductors and first and second layers of a polyimide film covering the conductors. The polyimide film preferably is coated with a fluoropolymer, such as fluorinated ethylene propylene (FEP). During manufacture of the thermocouple ribbon, the first and second layers of polyimide film, with the pair of flat conductors positioned there between, are heated above the melting temperature of the FEP. The completed thermocouple ribbon is then cooled. A thermocouple connector may then be attached to a first end of the thermocouple ribbon, while a welded thermocouple junction may be formed at a second end of the thermocouple ribbon.
1. A thermocouple ribbon comprising:
a) a pair of flat conductors constructed from a pair of dissimilar alloys, wherein the conductors are flat throughout their entire length, thereby minimizing an overall thickness of the thermocouple ribbon;
b) an upper layer of polyimide film laminating the pair of flat conductors; and
c) a lower layer of polyimide film laminating the pair of flat conductors,
the upper layer and the lower layer of polyimide film each comprising a layer of polyimide and a layer of fluoropolymer, wherein the upper layer and the lower layer of polyimide film provide a vacuum seal integrity along the entire length of the thermocouple ribbon, wherein each layer of fluoropolymer is 2 mils thick in both the upper layer and the lower layer of polyimide film,
wherein the vacuum seal integrity is created by heating the upper layer and the lower layer of the polyimide film to increase the temperature of each of the layers of fluoropolymer to a melting point of the fluoropolymer, and upon cooling, the layers of fluoropolymer solidify and bond the thermocouple ribbon together,
wherein the conductors are approximately 4 mils thick and further wherein the overall thickness of the thermocouple ribbon is approximately 12 mils.
2. The thermocouple ribbon of claim 1 wherein the fluoropolymer is fluorinated ethylene propylene.
3. The thermocouple ribbon of claim 2 wherein each layer of polyimide is approximately 2 mils thick.
4. The thermocouple ribbon of claim 1 wherein a width of the thermocouple ribbon is approximately 0.25 inches or less.
5. A thermocouple assembly comprising:
a) a ribbon including:
i. a pair of flat conductors constructed from a pair of dissimilar alloys, wherein the conductors are flat throughout their entire length, thereby minimizing an overall thickness of the thermocouple ribbon;
ii. an upper layer of polyimide film laminating the pair of flat conductors; and
iii) a lower layer of polyimide film laminating the pair of flat conductors,
the upper layer and the lower layer of polyimide film each comprising a layer of polyimide and a layer of fluoropolymer, wherein the upper layer and the lower layer of polyimide film provide a vacuum seal integrity along the entire length of the thermocouple ribbon, wherein each layer of fluoropolymer is 2 mils thick in both the upper layer and the lower layer of polyimide film,
wherein the vacuum seal integrity is created by heating the upper layer and the lower layer of the polyimide film to increase the temperature of each of the layers of fluoropolymer to a melting point of the fluoropolymer, and upon cooling, the layers of fluoropolymer solidify and bond the thermocouple ribbon together;
b) a thermocouple connector attached to a first end of the ribbon,
wherein the conductors are approximately 4 mils thick and further wherein the overall thickness of the thermocouple ribbon is approximately 12 mils.
6. The thermocouple assembly of claim 5 further comprising a welded thermocouple junction at a second end of the ribbon.
7. The thermocouple assembly of claim 5 wherein the fluoropolymer is fluorinated ethylene propylene.
8. The thermocouple assembly of claim 7 wherein each layer of polyimide is approximately 2 mils thick.
9. The thermocouple assembly of claim 5 wherein a width of the thermocouple ribbon is approximately 0.25 inches or less.