JPS59155733A - Force converter - Google Patents

Abstract

PURPOSE:To obtain a miniatruized force converter enhanced in sensitivity and free from the drift or hysteresis of an output signal, by using a semiconduction diaphragm. CONSTITUTION:A diaphragm 20 is provided to the center part of a cap 19 and a projection 21 is further formed to the center part of the diaphragm 20. This projection 21 is arranged so as to receive external force. The space surrounded by the projection 21, the cap 19 and the diaphragm 20 is filled with a fluid 22. The fluid 20 may be gas such as air or nitrogen or a liquid such as silicone rubber but pref. comprises a material low in coefficient of thermal expansion from the standpoint of temp. characteristics. When force is applied to the projection 21, the fluid 20 is compressed to be converted to the fluid pressure to the diaphragm 20. Because the diaphragm 20 is bent by said fluid pressure, the resistance value of the diaphragm 20 is changed and detected as a voltage output signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to force transducers, and more particularly to a psychokinetic transducer using a semiconductor diaphragm type sensor.

With recent advances in semiconductor technology, devices using semiconductor diaphragms are being put into practical use in pressure detectors for fluids such as air, water, oil, etc., pressure-to-electrical signal converters, and the like. Silicon, which is inexpensive and has a large strain-resistance change coefficient (so-called gauge factor), is often used for semiconductors.

FIG. 1 is a sectional view of an example of a conventional silicon diaphragm pressure transducer.

A diaphragm 2 of M thickness is provided in the center of the silicon die 1 by a well-known method such as ultrasonic machining, electric discharge machining, anisotropic etching, etc., and a plurality of diffusion layers 3 are formed to include a part of this diaphragm. establish. The diffusion layer 3 has a conductivity type opposite to that of the die 1, and the diffusion layer 3 and the die 1 form a PH1 combination. die 1
An insulating film 4 such as 5i (h) is deposited on the main surface of the substrate, a window is opened in the diffusion layer 3, and a metal wiring 5 is provided.

The package consists of a base part 7 and a cap 9, each of which is attached with a vibrator 8, 1o for introducing fluid. An external lead-out terminal 11 is drawn out from the base portion 7 while being electrically insulated from the pace.

After fixing the die 1 to the base part 7 via an adhesive 6 and connecting the external lead terminal 11 and the metal wiring 5 with a metal wire 12, a cap 9 is hermetically sealed around the base part 7.

In the pressure transducer configured in this manner, when fluids are introduced into the pipes 8 and 10, if there is a pressure difference between these fluids, the diaphragm 2 is pushed by the higher pressure fluid and deforms. This deformation causes the resistance value of the diaphragm 2 to change. A change in resistance value can be detected as a voltage change by flowing a constant current between the two diffusion layers 3.

This diaphragm pressure transducer is suitable for measuring fluid pressure, i.e. force per unit area (usually expressed in units of klil/c-), but when compared to units of force (k17/ctA). kg) is not suitable for measuring weight.

On the other hand, robots are increasingly being used in various industries, and in order to control the grasping force of these robots when grasping an object, a transducer that detects the tactile sensation when grasping an object is required. It has become an essential element for robots. This tactile sensing transducer requires a force sensor rather than a pressure sensor.

The aforementioned semiconductor diaphragm type pressure transducer has the disadvantage that it cannot be used because it is a pressure detector and not a force detector. Therefore, a load measuring device called a so-called load cell has been used for a long time. However, conventional load cells have drawbacks such as difficulty in miniaturization, difficulty in obtaining high sensitivity, drift in output signals, and appearance of hysteresis characteristics.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to achieve small size, high sensitivity, and low cost by using a semiconductor diaphragm.
Moreover, it is an object of the present invention to provide a force transducer without drift or hysteresis in the output signal.

The force transducer of the present invention includes a semiconductor die having a diaphragm whose central part is thinner than its peripheral part, and a plurality of semiconductor chips provided on one main surface of the semiconductor die so as to partially include the diaphragm region. a base portion of a package having a terminal for external extraction, to which the semiconductor die is fixed and electrically connecting the diffusion layer and the terminal for external extraction, and a base portion of the package hermetically sealed around the base portion. The device includes a cap and a diaphragm provided in a portion of the cap.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a sectional view of one embodiment of the present invention.

The semiconductor die 1 and the base portion 7 of the package are the same as described in FIG. The cap is different from the traditional one. A diaphragm 20 is provided in the center of the cap 19. Furthermore, a protrusion 2 is provided at the center of the diaphragm 20.
Form 1. This projection 21 is arranged so that a force can be applied to this projection from the outside. Base part 7. cap 19
．． A space surrounded by the diaphragm 20 is filled with a fluid 22. The fluid may be a gas such as air or nitrogen, or a liquid such as silicone rubber, but from the viewpoint of hot water properties, it is preferable to use a material with a low coefficient of thermal expansion.

It is preferable that the diaphragm 20 is made of a material with high rigidity, and it is preferable that the protrusion 21 can only move in the vertical direction in the figure. In order to meet this requirement, it is preferable to provide a plurality of concentric corrugations in the thin stainless steel plate.

In the force transducer configured in this way, when a force is applied to the protrusion 21, the fluid 22 is compressed and converted into fluid pressure to the diaphragm 2. This fluid pressure causes the diaphragm 2 to deflect, so that the resistance value of the diaphragm 2 changes. This resistance value is detected as a voltage output signal in the same manner as explained in FIG.

In the above embodiment, the fluid introduction pipe 8 is open, but the pipe 8 may have a closed structure or a structure in which the base portion 7 does not have a through hole and the pipe 8 does not exist. In such a non-open structure, the space below the diaphragm 2 is evacuated or filled with air, nitrogen gas, silicone rubber, or the like. Further, in the above embodiment, the semiconductor die 1
Although the diaphragm 2 is made of silicon, it goes without saying that it may be made of a semiconductor other than silicon, such as a -v group compound such as QaAs, Ge6-almanium, or the like.

As explained in detail above, according to the present invention, a force transducer that does not have output signal drift or hysteresis unlike conventional load cells, and can achieve small size, high sensitivity, and low cost can be obtained. is big.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an example of a conventional silicon diaphragm pressure transducer, and FIG. 2 is a sectional view of an embodiment of the present invention. 1...Silicon die% 2...Diaphragm, 3...Diffusion layer, 4...Insulating film, Death...Kanato wiring, 6...Adhesive, 7
...Base part of the package, 8 ... Pipe, 9 ... Cap, 10 ... Pipe, 11 ... External drawer terminal, 12...
...Thin metal wire, 19...Cap, 20...
...Diaphragm, 217- Atsushi Figure 1 No. ? figure

Claims (1)

[Claims] A semiconductor die having a diaphragm whose center portion is thinner than a peripheral portion, a plurality of diffusion layers provided on one main surface of the semiconductor die so as to partially include the diaphragm region, and an external lead terminal. A base portion of a package to which the semiconductor die is fixed and the diffusion layer and an external lead-out terminal are electrically connected, a cap of the package hermetically sealed around the base portion, and a part of the cap. A patented force transducer comprising: a diaphragm;