SU1027549A1 - Integral pressure converter - Google Patents

Description

The invention relates to a measurement technique, in particular, to a primary pressure transducer.

Integral pressure transducers made from gloonocrystalline silicon are known. The elastic element is a silicon membrane, in the body of which strain gauges are formed of resistance strain gages. On one side of the membrane, there is a reference pressure cavity formed by a shaped cap. External electrical leads are attached to the metallized contact pad, located on the periphery of the converter crystal along one side of it 1.

The disadvantage of the transducers is the impossibility of reducing the geometric dimensions of the transducer crystal, namely, the area occupied by the contact pads.

The closest in technical essence to the present invention is an integrated pressure transducer comprising a rectangular semiconductor wafer made of monocrystalline n-type silicon with surface orientation in the crystallographic plane (100). In a crystal, an membrane is formed by anisotropic etching, on which a pavement circuit of integral p-type strain gages is made. The converter also contains a silicon cap, hermetically connected to the crystal, which forms a cavity on one side of the membrane (on the side of the manufactured strain gauges). External electrical leads attached to the metallized contact pads located on the periphery of the crystal, along its short side 2 J.

A disadvantage of the known converter is the impossibility of reducing the overall size of the converter crystal, namely, its width. This is due to the fact that when the contact pads are located along one side of the crystal, the minimum size of this side is limited by the size of the contact pads and the gaps between them. In turn, the distance between KOH-I tact pads in this design provides air mutual isolation of contact pads with electrical terminals attached to them and therefore must be large enough to eliminate C1 "hiccups of the latter during the micro-soldering process.

The purpose of the invention is to reduce the transverse dimensions of the transducer.

This goal is achieved by the fact that on the surface of the lid adjacent to the plate, on the side of the outer side surface, there are blind grooves corresponding to the number of contact pads with leads, with the cavities of the grooves filled with bonding material.

In the proposed construction, the minimum distance between the edges of adjacent contact pads is determined by the minimum thickness of the walls of the lid separating the cavities, and can be as little as several microns. This reduces the width of the converter crystal. The separating walls of the cover also provide mechanical separation of the cavities, which prevents the spreading of the contact material,

Q of electrical connection pins with contact pads. This allows refusal. from specialized micro-soldering equipment. Filling cavities

5 with binder leads increases the mechanical strength of bonding the leads to the crystal and the lid due to an increase in the surface area of the bonded elements.

0

FIG. Figure 1 shows an integrated pressure transmitter, longitudinal section; FIG. 2 transducer with a cover of monocrystalline silicon with a surface orientation in the crystallographic plane (100), a cross-section / in FIG. 3 - converter with silicon lid oriented in the plane (110, transverse

0 cut.

The integral pressure transducer contains a rectangular semiconductor plate 1 with a membrane 2 and a lid 3 fastened to the plate with the help of the connecting layer 4. The lid is designed so that it forms a cavity 5 of the reference pressure above the membrane 2

P over metallized: contact pads b — cavities 7 isolated from one another. The external electrical leads 8 placed in cavity 7 are electrically connected to contact pads 6 by means of contact material 9 (for example, solder, conductive adhesive and TnJ Cavity 7 are filled with a binder 10, providing additional mechanical fastening of the leads 8. with a cover and a plate.

The converter cover (Fig. 2) has grooves with a V-shaped profile. Such a lid, for example, can

5 to be obtained by anisotropic etching of a silicon wafer oriented in the plane (100. The longitudinal direction of the grooves coincides with the crystallographic direction of the -ji 100 family on the krzhik plane. In the converter (Fig. 3), the single-crystal silicon crest has grooves with vertical walls. The plane of the lid coincides with the crystallographic plane (110} i and the longitudinal direction of the grooves with the crystallographic direction of the family. 112.,

The converter works as follows.

The measured pressure acts on the membrane 2, the resistance of the strain gauges changes, and the necessary signal is taken at the output of the measuring circuit.

Thus, the proposed design makes it possible to reduce the transverse overall size of the transducer, which makes it possible to create subminiature measuring transducers for various fields of science and technology.

FIG. 3

Claims (1)

(57 I INTEGRAL PRESSURE TRANSDUCER, comprising a membrane made in a rectangular semiconductor wafer with strain gauges placed on it, contact pads, the terminals of which are located on the wafer along its short side, and the membrane on the side of the strain gauges is closed by a dielectric cover, characterized in that, in order to reduce the transverse dimensions of the transducer, on the surface of the cover adjacent to the plate, from the side of the outer side surface, blind grooves are made, respectively, in number pads with leads, grooves filled with rial. moreover, the cavity of the binder