Strain gauge including a barrier layer over a resistance body
A strain gauge includes a flexible substrate; a resistor made from a film containing Cr, CrN, and Cr2N, on one surface of the substrate; and a resin barrier layer covering the resistor, and, in this strain gauge, in the barrier layer, a ratio of a moisture permeability (g/m2/24h) to a thickness (mm) is 5:1 or greater, and the thickness of the barrier layer is 100 μm or more and 3 mm or less.
1. A strain gauge comprising:
a flexible substrate;
a resistor made from a film containing Cr, CrN, and Cr 2 N, on one surface of the substrate;
a barrier layer covering the resistor, the barrier layer being made of resin; and
an insulating stress relaxing layer between the resistor and the barrier layer,
wherein, in the barrier layer, a ratio of moisture permeability (g/m 2 /24h) to thickness (mm) is 5:1 or greater, and the thickness of the barrier layer is 100 μm or more and 3 mm or less,
wherein the insulating stress relaxing layer is an organic film having a lower Young's modulus than the barrier layer.
2. The strain gauge according to claim 1 , wherein the barrier layer is made from a fluoropolymer, an epoxy resin, or an acrylic resin.
3. The strain gauge according to claim 1 , wherein the barrier layer covers an upper surface and side surfaces of the resistor in a continuous manner.
4. The strain gauge according to claim 1 , wherein a gauge factor is 10 or more.
5. The strain gauge according to claim 1 , wherein the CrN and the Cr 2 N contained in the resistor are 20% by weight or less.
6. The strain gauge according to claim 5 , wherein a proportion of the Cr 2 N in the CrN and the Cr 2 N is 80% or more by weight and less than 90% by weight.
7. The strain gauge according to claim 1 , wherein the organic film includes resin or rubber.
8. The strain gauge according to claim 1 , wherein an entire material of the insulating stress relaxing layer is insulating.
9. A strain gauge comprising:
a flexible substrate;
a resistor made from a film containing Cr, CrN, and Cr 2 N, on one surface of the substrate;
a barrier layer covering the resistor, the barrier layer being made of resin; and
an insulating stress relaxing layer between the resistor and the barrier layer,
wherein, in the barrier layer, a ratio of moisture permeability (g/m 2 /24h) to thickness (mm) is 5:1 or greater, and the thickness of the barrier layer is 100 μm or more and 3 mm or less,
wherein an entire perimeter of the insulating stress relaxing layer is enclosed by the barrier layer.
10. A strain gauge comprising:
a flexible substrate;
a resistor made from a film containing Cr, CrN, and Cr 2 N, on one surface of the substrate;
a barrier layer covering the resistor, the barrier layer being made of resin; and
an electrode electrically connected to the resistor, the electrode having a first sidewall facing a second sidewall of the barrier layer,
wherein, in the barrier layer, a ratio of moisture permeability (g/m 2 /24h) to thickness (mm) is 5:1 or greater, and the thickness of the barrier layer is 100 μm or more and 3 mm or less,
wherein a portion of the flexible substrate is exposed to a gap between the first sidewall of the electrode and the second sidewall of the barrier layer.