JP2008089412A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and lightweight pressure sensor. <P>SOLUTION: In the pressure sensor 1 provided with a pressure detection element 4 in the middle of or on the depth side of a through hole 5 formed in a protrusion part 3, main body parts (a base part 2 and the protrusion part 3) are constituted as a molded interconnect device which is molded of ceramic in a prescribed shape and in which conductor patterns 6 are formed in its surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure sensor.

  Conventionally, a pressure sensor in which a sensor chip is attached so as to close one end of a through hole as a pressure introduction hole formed in a package body is known (for example, Patent Document 1).

In the pressure sensor disclosed in Patent Document 1, a sensor chip is mounted on a package body made of a resin material via a glass pedestal. This glass pedestal has a function of reinforcing the package body to ensure the required detection accuracy of the sensor chip by ensuring the required detection accuracy.
Japanese Patent Laid-Open No. 10-300604

  However, the conventional pressure sensor has a problem that the size is increased and the weight is increased by the amount of the glass pedestal.

  Accordingly, an object of the present invention is to obtain a smaller and lighter pressure sensor.

  In the invention of claim 1, in the pressure sensor having a pressure detecting element arranged in the middle or the back side of the through hole formed in the main body, the main body is formed into a predetermined shape and the surface It is characterized in that it is configured as a three-dimensional circuit board on which a conductor pattern is formed.

  The invention according to claim 2 is characterized in that the pressure detecting element is flip-chip mounted on the main body.

  According to a third aspect of the present invention, a concave portion having a bottom surface and a step surface is formed in the main body portion, the through hole is formed to open to the bottom surface, and the pressure detection element is mounted on the bottom surface. In addition, an element different from the pressure detecting element is mounted on the step surface.

  In the invention of claim 4, a concave portion is formed in the main body portion, the through hole is formed to open to the bottom surface of the concave portion, a pressure detecting element is mounted on the bottom surface, and the conductor pattern is formed. The inner surface of the concave portion and the side wall surface of the main body portion are connected across the opening edge of the concave portion.

  The invention according to claim 5 is characterized in that the concave portion is vacuum-sealed.

  According to the invention of claim 1, since the main body is formed of ceramic, the required rigidity and strength can be secured by the main body itself without providing a glass pedestal, and the required detection accuracy of the pressure detecting element is ensured. can do.

  According to the second aspect of the present invention, since the pressure detection element is flip-chip mounted on the main body, it is possible to save the manufacturing labor and shorten the manufacturing tact time compared to the case where the pressure detection element is mounted by wire bonding. In addition, the manufacturing cost can be reduced.

  According to the invention of claim 3, by using the bottom surface and the step surface of the stepped recess, the pressure detection element and the another element can be mounted in multiple stages, and a pressure sensor including the another element is provided. It can be obtained as a more compact configuration.

  According to the fourth aspect of the present invention, the potential of each electrode of the element can be easily taken out from the side wall surface of the main body by the conductor pattern straddling the opening edge of the recess.

  According to the fifth aspect of the present invention, since the concave portion on the side opposite to the detection side (back side) of the pressure detection element is vacuum-sealed, the absolute pressure can be measured.

  (First Embodiment) FIG. 1 is a perspective view of a pressure sensor according to the present embodiment, FIG. 2 is a plan view of the pressure sensor viewed from the back side (opposite side to the detection side by the pressure detection element), and FIG. 2 is a sectional view taken along the line III-III in FIG. 2, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2, and FIG. 5 is a plan view of the pressure sensor as viewed from the back side. FIG. 6 is a side view showing a state where the pressure sensor is mounted.

  The pressure sensor 1 according to the present embodiment has a configuration in which a substantially cylindrical protrusion 3 is provided on one plane (seal surface) 2e of a base 2 having a substantially rectangular parallelepiped appearance. In the present embodiment, the base body 2 and the protrusion 3 correspond to the main body.

  The main body (base 2 and protrusion 3) is configured as a 3D circuit component (3D circuit board; MID: Molded Interconnect Device). In the present embodiment, the main body portion can be obtained by forming a ceramic material into a predetermined shape by, for example, injection molding and forming the conductor pattern 6 on the surface, and various known MID methods (for example, UV exposure method (for example, UV exposure method ( Subtractive method, semi-additive method, additive method, etc.), laser imaging method, one-time molding method such as IVOND method, and two-time molding method such as SKW method.

  This main body can be molded by ceramic injection molding (powder injection molding method using ceramic powder as a raw material; CIM). Specifically, the ceramic powder is filled with a binder (filling flow into a mold). In the injection molding machine equipped with a mold, mixing low-molecular-weight components such as wax, high-molecular-weight components such as thermoplastic synthetic resin, etc. in an appropriate ratio) This is a technique of forming a so-called green body, and then degreasing to remove the binder and heat-treating the powder at a temperature below the melting point to obtain a product having a predetermined shape by sintering in which bonding occurs between the powder particles. In this case, the binder may be any material that can be molded and can be decomposed and volatilized by overheating degreasing. As an example, a composition of polystyrene 60% (mass%), paraffin wax 20%, and stearic acid 20% is used. The thing which has can be used. Moreover, it is suitable that the usage-amount of a binder shall be about 15-25% (mass%) of a binder with respect to 100% of ceramic powder, for example. In addition, it becomes possible to improve toughness by mixing silica or zirconia into the ceramic powder.

  Further, the main body can be formed by ceramic compression molding (press molding). In this case, for example, a binder having a composition of 100% acrylic polymer (mass%) or 100% PVA (polyvinyl alcohol) can be used as the binder. The amount of the binder used is 100% of the ceramic powder. The binder is preferably about 4 to 6% (mass%).

  Further, as shown in FIG. 3, a through hole 5 is formed in the central portion of the projecting portion 3 so as to penetrate the projecting portion 3 in the axial direction, and a mounting male screw 3a is formed on the outer peripheral portion thereof. Yes.

  On the other hand, as shown in FIGS. 3 and 4, a concave portion 2a having a substantially rectangular shape in a plan view is formed on a portion of the base portion 2 on the side opposite to the side where the protruding portion 3 is provided. Further, a through hole 5 formed in the protrusion 3 is opened at a substantially central portion of the bottom surface 2b of the recess 2a.

  And as shown in FIGS. 3-5, the pressure detection element 4 is mounted in the state which closes the opening end (one end of the extending | stretching direction of the through-hole 5) in the bottom face 2b of the through-hole 5. As shown in FIG. This pressure detecting element 4 is formed by forming a pressure receiving surface on one surface of a single crystal silicon substrate, and includes a diaphragm, a strain gauge, an electrode, etc. (all not shown), and converts pressure into electric resistance by a piezoresistive effect. To do. The through hole 5 corresponds to a pressure introducing hole.

  In the present embodiment, the pressure detection element 4 is flip-chip mounted on the conductor pattern 6 formed on the bottom surface 2b as shown in FIG. In the figure, 8 is a conductive adhesive, 9 is an underfill (resin insulating adhesive), and 10 is a bump of each electrode of the pressure detecting element 4.

  At this time, as shown by A in FIG. 5, the underfill 9 is arranged in a substantially rectangular ring shape along the outer edge of the pressure detection element 4, and the underfill 9 and the pressure detection element 4 form a through hole. The entry (leakage) of the detection target fluid (liquid or gas) from 5 into the recess 2a is suppressed. That is, the underfill 9 also functions as a seal member. Further, by using a material with high heat dissipation (for example, a silicon-based resin material) as the underfill 9, it is possible to increase the heat resistance of the pressure sensor 1 and to suppress detection errors due to the temperature of the pressure detection element 4.

  The conductor pattern 6 can be appropriately formed using various processes such as physical vapor deposition, removal of unnecessary portions by irradiation of electromagnetic waves such as laser, and pressure film formation by electrolytic plating.

  Here, as shown in FIGS. 2 to 5, the conductor pattern 6 connects the inner surface of the concave portion 2 a and the side wall surface 2 d of the main body (base portion 2) across the opening edge 2 c of the concave portion 2 a. Is formed. Therefore, the detection result of the pressure detection element 4 can be easily obtained by establishing conduction with the conductor pattern 6 exposed on the side wall surface 2d.

  The recess 2 a is closed on the opposite side of the protrusion 3 by a flat lid 7. As described above, after mounting the pressure detection element 4 while securing the seal by the underfill 9, the cover 2 is closed in the vacuum chamber, whereby the recess 2a can be vacuum-sealed. In this case, the absolute pressure can be detected by the pressure detection element 4. In addition, when not vacuum-sealing, the relative pressure (gauge pressure) with respect to atmospheric pressure is detected.

  The pressure sensor 1 having the above configuration can be equipped in a state as shown in FIG. 6, for example. That is, in this example, a female screw hole 20a corresponding to the male screw portion 3a of the protrusion 3 is formed in the partition wall 20 (for example, a tube wall) of the fluid existence region 21 to be detected, and the protrusion is formed in the female screw hole 20a. By screwing the portion 3, an annular seal member 12 (washer, gasket, O-ring, etc.) is sandwiched between the surface 20 b of the partition wall 20 and the flat surface 2 e on the side where the protrusion 3 of the base portion 2 is formed, The seal member 12 ensures a fluid seal.

  According to the above embodiment, since the main body (base 2 and protrusion 3) is formed of ceramic, rigidity and strength are ensured by the main body itself without providing a glass pedestal, and the pressure detection element 4 is required. It is easy to ensure the detection accuracy.

  In addition, according to the present embodiment, since the pressure detection element 4 is flip-chip mounted on the main body, it is possible to save the manufacturing labor and shorten the manufacturing tact time compared to the case where the pressure detection element 4 is mounted by wire bonding. In addition, the manufacturing cost can be reduced.

  Further, according to the present embodiment, the potential of each electrode of the pressure detection element 4 can be easily taken out from the side wall surface 2d of the main body portion by the conductor pattern 6 straddling the opening edge 2c of the recess 2a.

  In the present embodiment, the absolute pressure can be measured by vacuum-sealing the concave portion 2a on the side opposite to the detection side (back side) of the pressure detection element 4.

  (Second Embodiment) FIG. 7 is a longitudinal sectional view (cross-sectional view corresponding to FIG. 3) of a pressure sensor according to this embodiment. In addition, 1 A of pressure sensors concerning this embodiment are provided with the component similar to the pressure sensor 1 concerning the said 1st Embodiment. Therefore, in the following, those similar components are denoted by common reference numerals, and redundant description is omitted.

  In the present embodiment, a stepped recess 2a having a bottom surface 2b and a step surface 2f formed at a substantially central portion in the depth direction is formed on the base 2A, and the pressure detection element 4 is mounted on the bottom surface 2b. In addition, an element other than the pressure detection element 4 (for example, an element including a circuit that processes an output signal from the pressure detection element 4 (for example, filtering, correction, calculation, temperature compensation, etc.)) is mounted on the step surface 2f. Except for this point, it has the same configuration as the pressure sensor 1 according to the first embodiment.

  According to such a configuration, the pressure detection element 4 and the another element 4A can be mounted in multiple stages using the bottom surface 2b and the step surface 2f of the stepped recess 2a, and the other element 4A is provided. The pressure sensor 1A can be obtained as a more compact configuration.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made.

  For example, although the case where the pressure sensor was provided in the back side of the through-hole was illustrated in the said embodiment, you may mount a pressure sensor in the flange provided in the middle of the through-hole.

  Moreover, although the case where the external thread for attachment was formed in the projection part was illustrated in the said embodiment, it may replace with this and the internal thread for attachment may be formed in the internal peripheral surface of a through-hole. Further, the protruding portion may be tapered.

  In addition, the outer surface of the main body is coated with a magnetic material or a conductive material (for example, composite plating of carbon nanotubes and nickel), so that the effects of external electromagnetic waves (occurrence of detection errors, noise mixing, etc.) ) Can be suppressed.

The perspective view of the pressure sensor concerning the embodiment of the present invention. The top view which looked at the pressure sensor concerning 1st Embodiment of this invention from the back surface side (opposite side of the detection side by a pressure detection element). III-III sectional drawing of FIG. IV-IV sectional drawing of FIG. It is the top view which looked at the pressure sensor concerning 1st Embodiment of this invention from the back surface side, Comprising: The figure which shows the sealing area | region of the pressure detection element by sealing agent. The side view (partial sectional view) showing the state where the pressure sensor concerning a 1st embodiment of the present invention was mounted. The longitudinal cross-sectional view of the pressure sensor concerning 2nd Embodiment of this invention.

Explanation of symbols

1,1A Pressure sensor 2,2A Base part (main part)
2a Concave part 2b Bottom face 2c Opening edge part 2d Side wall surface 2f Step surface 3 Protrusion part 4 Pressure detection element 4A Another element 5 Through hole 6 Conductor pattern

Claims (5)

In the pressure sensor having a pressure detection element arranged in the middle or the back side of the through hole formed in the main body,
A pressure sensor characterized in that the main body portion is formed as a three-dimensional circuit board in which a ceramic is molded into a predetermined shape and a conductor pattern is formed on the surface.   The pressure sensor according to claim 1, wherein the pressure detection element is flip-chip mounted on a main body portion. Forming a recess having a bottom surface and a step surface in the main body, and forming the through-hole to open to the bottom surface;
The pressure sensor according to claim 1, wherein the pressure detection element is mounted on the bottom surface, and an element different from the pressure detection element is mounted on the stepped surface. Forming a recess in the main body, and forming the through hole so as to open to the bottom surface of the recess,
A pressure detection element is mounted on the bottom surface,
The pressure sensor according to claim 1, wherein the conductor pattern is formed so as to connect the inner surface of the recess and the side wall surface of the main body across the opening edge of the recess.   The pressure sensor according to claim 3 or 4, wherein the concave portion is vacuum-sealed.

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