JPS61222273A - Semiconductor pressure transducer - Google Patents

Abstract

PURPOSE:To make it possible to provide highly sensitive, highly accurate characteristics in both positive-pressure and negative-pressure within a minute differential pressure range, by providing a pressure sensitive element, which is excellent in positive-pressure characteristics and a pressure sensitive element, which is excellent in negative-pressure characteristics. CONSTITUTION:A semiconductor pressure transducer 20 is provided with a semiconductor pressure sensitive element 11, in which a pressure sensitive element 12 having excellent positive-pressure characteristics and a pressure sensitive element 13 having excellent negative-pressure characteristics are provided. When an input is positive-pressure, the output of he positive-pressure measuring diffused resistor 12 is selectively outputted from an electric circuit. When the input is negative-pressure, the output of the negative-pressure measuring diffused resistor 13 is selectively outputted from the electric circuit. The sensitivities are electrically corrected, and the sensitivities of the positive pressure and the negative-pressure pressure are aligned. Thus the linearity of the positive- pressure and the negative-pressure are equally controlled. Both the positive- pressure and the negative-pressure have excellent linearily.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to semiconductor pressure transducers.

[Technical background of the invention]

Conventionally, semiconductor pressure transducers capable of measuring a minute differential pressure of about 10 to 100 n2o have been used to measure the pressure, flow rate, etc. of industrial glands. The conventional semiconductor pressure transducer is as shown in FIG.
Similarly to the one for high pressure of 500W-, diaphragm 1 is
Diaphragm 1 is used in the structure shown in Figure 2.
It is a well-formed pressure-sensitive element. The pressure sensitive element 2 is mounted on a base 3. The base 3 is housed within the envelope 4. A lead bin 5 is provided on the peripheral wall of the envelope 40.
is penetrated. A bonding wire 6 is installed between the end of the lead bin 5 and the pressure sensitive element 2.

[Problems with background technology]

In such a conventional semiconductor pressure transducer, when the diameter of the diaphragm is set to a constant value at a slight differential pressure, the diaphragm part of the pressure-sensitive element 2 must be designed to be extremely thin. When set, a so-called balloon effect occurs in which the output characteristics become non-intuitive. Therefore, with conventional semiconductor pressure transducers, positive pressure and
It was difficult to obtain the desired sensitivity and linearity (accuracy) for both negative pressure and negative pressure.

Note that the balloon effect is defined as 1 mechanical strain when the diaphragm undergoes a large deflection in the range of WVh≧0.4, where Wo is the deflection at the center of the sensor and h is the thickness of the diaphragm. This is a phenomenon in which the output of a pressure transducer has nonlinearity of, for example, about 1% or more due to nonlinearity with stress. Assuming that the sensitivity is constant, a thinner diaphragm tends to cause a balloon effect (see FIG. 8).

[Purpose of the invention]

An object of the present invention is to provide a semiconductor pressure transducer having highly sensitive and highly accurate characteristics in a slight differential pressure range.

[Summary of the invention]

The present invention provides a pressure sensitive element with excellent positive pressure characteristics and a pressure sensitive element with excellent negative pressure characteristics, outputs from both elements simultaneously, and always has good characteristics in both positive pressure and negative pressure areas. This semiconductor pressure transducer has high sensitivity and high precision characteristics in the slight differential pressure range by obtaining output from the elements.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of the present invention. FIG. 2
This is a semiconductor pressure-sensitive element formed individually. The semiconductor pressure sensitive element 11 is mounted on a base 14. On the base 14,
A pressure inlet passage 15 is formed which leads to the diaphragm part 12.13. The semiconductor pressure sensitive element 11 and the base 14 are housed in an envelope 16. Lead pins 11 serving as output terminals are inserted through the wall of the envelope 16 . A bonding wire 18 is connected between the lead pin 17 and the semiconductor pressure sensitive element 11.
has been erected. The pressure input path 15 within the base 14 communicates with a pressure input path 19 formed in the envelope 16 .

Here, the inner surface of the thin wall portion forming the diaphragm portion 12.13 has a flat surface JJa at the portion facing the pressure input path 15, and a portion K having a convex portion 13a. Therefore, there is linearity as a noclameter representing the nonlinearity of the input-output of the pressure transducer. Linearity refers to the maximum output (
It is the deviation of the output from the human power with respect to the maximum input (100%), and is expressed by Lln of the 12th order equation.

Linearity = Lin, ΔRmax is the change in resistance value at a pressure of pmax. As shown in FIG. 2, this linearity (Lln) depends on the amount of convex portions of the diaphragm portions 12 and 13. As is clear from the figure, when the amount of convex portions is small, the linearity of the negative force is poor and the linearity of the positive pressure side is good. When the amount of convex portions is large, the linearity on the positive pressure side is good and the linearity on the negative pressure side is poor. Note that (h) in FIG. 2 represents the amount of convex portions.

The semiconductor pressure transducer 20 configured in this manner can simultaneously take out the outputs of the diffused resistors from both diaphragm parts 12, 1j having different amounts of convex portions, and can select one of the outputs using an electrical circuit. There is. Finally, when the input is positive pressure, the output of the diffused resistor 12 for measuring positive pressure is selectively output from the electric circuit, and when the input is negative pressure, the output of the diffused resistor 13 for measuring negative pressure is selectively output from the electric circuit. be done.

Note that the sensitivity of the pressure-sensitive diffused resistor for positive pressure measurement and the pressure-sensitive diffused resistor for negative pressure measurement is not necessarily the same, so the sensitivity is corrected using an electric circuit to measure positive pressure.

Negative pressure sensitivity is the same.

The semiconductor pressure transducer 20 configured in this manner has linearity equally controlled on the positive pressure side and negative pressure side, as shown by the characteristic line (1) in FIG. Both have good linearity. As is clear from the figure, the linearity is
Both the positive pressure side and the negative pressure side are within about 0.8n. Incidentally, in the case of positive pressure, it is within about 0.3 inch, and in the case of negative pressure, it is within about 0.254 inch. This linearity is due to positive pressure,
When considering negative pressure, it can be seen that the characteristic line (IQ) in the figure is less than half of that in the conventional case.Moreover, the semiconductor pressure transducer LA of the embodiment
There is no need for special processing to form 13.

4 to 6 show other embodiments of the invention.

The semiconductor pressure transducer shown in FIG.
There are two pressure sensitive elements 31 and 32 separated in the
One is a pressure sensitive element 31 for measuring positive pressure, and the other is a pressure sensitive element 32 for measuring negative pressure.

That is, in one envelope 16, a pressure-sensitive diffused resistor for positive pressure measurement and a pressure-sensitive diffused resistor for negative pressure measurement are provided with separate diaphragm portions 31& for each.

32a.

FIGS. 5(6) and 5(B) show U in which one pressure-sensitive semiconductor element 41 is provided with two diaphragm parts 42, 43, FIG. 5(G) is a plan view, and FIG. FIG. The diaphragm section 42 at the center is a pressure sensitive section for measuring positive pressure, and the diaphragm section 43 at the periphery is a pressure sensitive section for measuring negative pressure.

FIG. 6 shows two pressure sensitive elements 51.in one envelope 16.
This is an example of one equipped with ls2. One diaphragm section 51 is a pressure sensitive section for measuring positive pressure.

The other diaphragm 52 is a pressure sensitive part for measuring negative pressure.The shapes of both diaphragm parts 51 and 52 are flat and have a small amount of convex parts6.Both diaphragms 51 and 52 have a flat shape and have a small amount of convex parts6. A type with good linearity with respect to pressure is prepared. By arranging the pressure sensitive elements in different directions, linearity is improved in each region on the positive pressure side and negative pressure side.

〔Effect of the invention〕

As explained above, the semiconductor pressure transducer according to the present invention has characteristics of high sensitivity and high precision in the range of slight differential pressure.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of the present invention,
FIGS. 2 and 3 are characteristic diagrams showing the relationship between output and linearity, FIGS. 4 to 6 are explanatory diagrams showing other embodiments of the present invention, and FIG. 7 is a conventional semiconductor pressure FIG. 8, which is an explanatory diagram showing the schematic configuration of the converter, is a characteristic diagram showing the relationship between output and sensitivity. I J-...Semiconductor pressure sensitive element, 12,1:l...Diaphragm portion, 14...Base, 15.19...Pressure path, 16...Envelope, 11... Lead bin, 18...
・Bonding wire, 20.30, 40.50...Semiconductor pressure transducer applicant's agent Patent attorney Takehiko Suzue 4th cause Figure 5

Claims (2)

[Claims] (1) A semiconductor pressure-sensitive element having a diffused resistance layer on one side and a plurality of thin-walled parts for forming diaphragms provided on the other side in contact with the diffused resistance layer; A base having a pressure input path leading to the diaphragm and mounting the semiconductor pressure-sensitive element, an envelope housing the base, and an output terminal electrically connected to the semiconductor pressure-sensitive element. A semiconductor pressure transducer comprising: (2) The semiconductor pressure transducer according to claim 1, wherein the thin wall portion forming the diaphragm has a flat surface and a convex portion in the center.