JPH073370B2 - Thin film sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention forms a strain gauge portion in a strain-generating body that is deformed by applying a load, and utilizes a resistance change due to these strain gauge portions to apply a mechanical load. The present invention relates to a thin film sensor adapted to convert an electric signal into an electric signal, and particularly to a thin film sensor having a strain gauge formed by a thin film technique.

Conventional technology Generally, in this type of thin-film sensor, in order to form a strain gauge by thin-film technology, an insulating layer is formed on the surface of the strain generating body, and a strain is applied by a metal layer having a small temperature coefficient of resistance on the insulating layer. A gauge portion is formed, a temperature compensation portion is formed on the gauge portion by a metal layer having a large resistance temperature coefficient, and a metal layer having a low electric resistance value is formed on these to form a lead wire portion. Then, a resin layer is formed on the entire surface to prevent moisture.

Problems to be Solved by the Invention A resin layer is formed on the surface to prevent moisture, but the strain gauge part and the temperature compensating part are located in the part sandwiched between the insulating layer and the resin layer when viewed from the side surface of the interlayer. To do. However, regarding the moisture proof property between the layers, the insulating layer and the resin layer are made of resin, and the adhesiveness between the resins is quite poor. Therefore, even if humidity does not enter from the surface side of the resin layer, the resin cannot be prevented from entering from the adhesive surface to the insulating layer, and sufficient moisture resistance cannot be obtained.

Means for Solving the Problems Providing a strain-generating body in which a deformable portion that deforms when a load is applied is formed, and an insulating layer is formed on the surface of the strain-generating body.
On this insulating layer, the strain gauge portion located in the deformed portion, the temperature compensation portion, and the lead wire portion connecting them are formed by thin film technology, and the strain gauge portion, the temperature compensation portion, and the lead connecting them are formed. A closed loop ring-shaped metal layer surrounding the wire portion is formed, and a moisture-proof layer is formed on the upper surface of the strain gauge, the temperature compensation portion, the lead wire portion, the ring-shaped metal layer, and the insulating layer. .

Function Although the adhesiveness between the resins is not good, the adhesiveness between the resin and metal is good, so a ring-shaped closed loop that surrounds the strain gauge section, temperature compensation section and the lead wire section that connects them The metal layer is interposed between the insulating layer and the resin layer to enhance the adhesiveness of this portion, which means that the boundary between the insulating layer and the resin layer is substantially adhered well. It is possible to obtain sufficient moisture resistance.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 4. First, the metallic flexure element 1 is provided. This flexure element 1 has a prismatic shape, and two holes 2 communicating with each other form a thin-walled deformed portion 3 at two upper and lower portions in total. One end is the fixed part 4 and the other end is the load application part 5.

An insulating layer 6 made of resin is formed on the entire surface of the strain-generating body 1. A metal thin film 7 having a small temperature coefficient of resistance, a metal thin film 8 having a large temperature coefficient of resistance, and a metal thin film 9 having a small resistance value are sequentially formed on the insulating layer 6 by a thin film technique such as vapor deposition and sputtering. Then, each of the metal thin films 7, 8 and 9 is etched to form the strain gauge portion 10 only by the metal thin film 7 having a small temperature coefficient of resistance. The layers form a span compensating section 11 and a balance compensating section 12, which are temperature compensating sections. In addition, the lead wire portion 13 is formed in a portion having a three-layer structure while leaving the metal thin film 9 having a small resistance value thereon. Then, a closed loop ring-shaped metal layer 14 surrounding the outer circumferences of the strain gauge portion 10, the span compensation portion 11, the balance compensation portion 12, and the lead wire portion 13 is formed. The ring-shaped metal layer 14 also has the same three-layer structure as the lead wire portion 13.

Then, the moisture-proof resin layer 15 is laminated on the entire surface thus formed.

In such a configuration, since the resin layer 15 itself is made of a material having excellent moisture resistance, humidity does not enter from the surface side thereof. However, since the adhesiveness between the side surface side and the insulating layer 6 is poor, there is a possibility that humidity may enter. However, since both the insulating layer 6 and the resin layer 15 made of resin adhere to each other at the portion of the ring-shaped metal layer 14, the adhesiveness at the boundary is high, and the ring-shaped metal layer 14 is formed in a closed loop shape. Therefore, humidity does not reach the strain gauge section 10, the span compensating section 11, the balance compensating section 12, and the lead wire section 13 located inside thereof. Therefore, sufficient moisture resistance is obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, part of the lead wire portion 13 is also used as the ring-shaped metal layer 14. That is, the ring-shaped metal layer
If the strain gauge section 10, the span compensating section 11, and the balance compensating section 12 do not exist in the outer peripheral portion of 14, the moisture resistance of the lead wire section 13 does not affect the performance, and therefore the same operation as in the above-described embodiment is performed. Is what you can get.

EFFECTS OF THE INVENTION As described above, the present invention provides a strain-generating body in which a deformable portion that deforms when a load is applied is provided, and an insulating layer is formed on the surface of the strain-generating body. The strain gauge portion located in the deformed portion, the temperature compensation portion, and the lead wire portion connecting them are formed by thin film technology, and the outside of the strain gauge portion, the temperature compensation portion, and the lead wire portion connecting them. A ring-shaped metal layer having a closed loop shape is formed to surround the strain gauge, the temperature compensating portion, the lead wire portion, the ring-shaped metal layer, and a moisture-proof layer on the upper surface of the insulating layer. Although the adhesiveness is not good, because the adhesiveness between resin and metal is good, the closed loop-shaped metal layer surrounding the strain gauge section, the temperature compensation section and the lead wire section connecting them is insulated. The layer and the resin layer are interposed to connect this part. Adhesion is improved, and thereby, the boundary portion between the insulating layer and the resin layer is substantially well adhered, and sufficient moisture resistance can be obtained.

[Brief description of drawings]

1 is a plan view showing a first embodiment of the present invention, FIG. 2 is a side view, FIG. 3 is a sectional view taken along the line AA in FIG. 1, and FIG.
FIG. 5 is a perspective view of a flexure element, and FIG. 5 is a plan view showing a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Strain element, 3 ... Deformation part, 6 ... Insulating layer, 10 ... Strain gauge part, 11 ... Span compensation part (temperature compensation part), 12 ... Balance compensation part (temperature compensation part), 13 ... Lead wire part, 14 ... Ring-shaped metal layer

Claims (2)

[Claims] 1. A strain-generating body having a deformable portion that is deformed when a load is applied is provided, an insulating layer is formed on the surface of the strain-generating body, and the deformable portion is positioned on the insulating layer. Forming a strain gauge part and a temperature compensating part and a lead wire part connecting them by a thin film technique, and enclosing the strain gauge part, the temperature compensating part and the lead wire part connecting them to each other in a closed loop shape. A thin film sensor, wherein a ring-shaped metal layer is formed, and a moisture-proof layer is formed on the upper surface of the strain gauge, the temperature compensation section, the lead wire section, the ring-shaped metal layer, and the insulating layer. 2. The thin film sensor according to claim 1, wherein a part of the lead wire portion is also used as a ring-shaped metal layer.