Strain detector and manufacturing method thereof
A strain detector includes a strain-causing portion, an insulation film formed on the strain-causing portion, a strain gauge formed on the insulation film and configured to detect the strain generated by the strain-causing portion as electric signals, an electrode connected to the strain gauge, a bonding pad extending from the electrode, a bonding wire connected to the bonding pad, and an insulative resin layer covering the strain gauge without covering the bonding pad and the bonding wire.
1. A strain detector comprising:
a strain-causing portion configured to cause a strain in response to an external stress;
an insulation film formed on at least a part of the strain-causing portion;
a strain gauge formed on the insulation film, the strain gauge being configured to detect the strain caused by the strain-causing portion as an electric signal;
an electrode connected to the strain gauge;
a bonding pad extended from the electrode and configured to export the electric signal to an outside;
a bonding wire connected to the bonding pad; and
an insulative resin layer at least covering the strain gauge without covering the bonding pad and the bonding wire,
wherein a thickness of the insulative resin layer is between about 2 μm to 500 μm.
2. The strain detector according to claim 1 , wherein
the insulative resin layer is formed from a silicone resin and has a Shore A hardness ranging from 10 to 100.
3. The strain detector according to claim 1 , wherein
the strain gauge includes four resistors, the insulative resin layer collectively covering the four resistors.
4. The strain detector according to claim 1 , wherein
the strain gauge includes four resistors, the insulative resin layer separately covering each of the four resistors.
5. The strain detector according to claim 1 , further comprising a protection film disposed on the strain gauge and the electrode, the protection film being covered with the insulative resin layer.
6. A method for producing a strain detector comprising:
a strain-causing portion configured to cause a strain in response to an external stress; an insulation film formed on at least a part of the strain-causing portion; a strain gauge formed on the insulation film, the strain gauge being configured to detect the strain caused by the strain-causing portion as an electric signal; an electrode connected to the strain gauge; a bonding pad extended from the electrode and configured to export the electric signal to an outside; and a bonding wire connected to the bonding pad, the method comprising:
prior to connecting the bonding wire to the bonding pad, covering at least the strain gauge using an insulative resin layer without covering the bonding pad, wherein a thickness of the insulative resin layer is between about 2 μm to 500 μm.
7. The method according to claim 6 , wherein the strain detector further comprises a protection film disposed on the strain gauge and the electrode, the protection film being covered with the insulative resin layer.