JP6128002B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor that detects the pressure of a measurement medium.

  Conventionally, a pressure sensor for detecting the pressure of a measurement medium is known. As this type of sensor, a pressure sensor has been proposed in which a housing is connected to a molded IC in which a sensor chip having a pressure-sensitive element portion is sealed with a mold resin and sealed with a connector case ( For example, Patent Document 1).

  The pressure sensor described in Patent Document 1 will be described more specifically. In this pressure sensor, a portion including the pressure sensitive element portion of the mold IC is configured to protrude from the connector case. A pressure chamber formed by a housing or the like is formed around the pressure sensitive element portion, and the pressure sensitive element portion is exposed without being sealed in the connector case and exposed to the pressure chamber formed by the housing or the like. doing. The housing is formed with a pressure introduction hole for introducing a measurement medium that is a pressure detection target into the pressure chamber. In this pressure sensor, when the measurement medium is introduced into the pressure chamber and a pressure is applied to the pressure-sensitive element portion, a sensor signal corresponding to the pressure is output and the pressure is detected.

  Here, the pressure sensor described in Patent Document 1 is configured such that the interface between the mold IC and the connector case is exposed to the pressure chamber.

Japanese Patent No. 3620184

  As described above, the pressure sensor described in Patent Document 1 is configured such that the interface between the mold IC and the connector case is exposed to the pressure chamber. And in this pressure sensor, the pressure by a measurement medium will be applied with respect to the part which protruded from the connector case among mold ICs. Here, in this pressure sensor, a gap may be formed between the mold IC and the connector case due to variations in the shape or physical properties (such as elastic modulus) of the mold IC and the connector case. When a gap is generated in this way, the pressure medium enters the gap, resulting in a pressure leak that causes the pressure medium to leak out of the apparatus, and pressure detection accuracy is deteriorated.

  In view of the above points, the present invention provides a pressure sensor configured by connecting a housing to a mold IC in which a sensor chip is sealed with a mold resin and sealed with a connector case, between the mold IC and the connector case. It is an object of the present invention to provide a configuration in which a measurement medium does not easily enter the gap.

  In order to achieve the above object, according to the first aspect of the present invention, a sensor chip (21) having a pressure-sensitive element portion for sensing pressure, and a mold resin (sealing the sensor chip while exposing the pressure-sensitive element portion) 22) and a mold IC (2) configured to have one surface (33a), and a connector that seals the mold IC by projecting a part of the mold IC including the pressure-sensitive element portion from the one surface. A pressure chamber (6) connected to the case (3) and the connector case to form a pressure chamber (6) around the pressure-sensitive element portion, and a pressure introduction hole (for introducing a measurement medium to be pressure-detected into the pressure chamber) 41), and a housing (4) having a configuration in which the interface between the mold IC and the connector case is exposed to the pressure chamber, and has the following characteristics.

That is, one surface is the side of the connector case from which the molded IC protrudes and is a contact surface that contacts the housing, and the molded IC has an outer wall surface (22b) protruding from one surface of the connector case. The pressure seal portion (33b) protrudes from one surface along the outer wall surface, and the pressure seal portion is sandwiched between the mold IC and the pressure chamber in a direction perpendicular to the outer wall surface.

  For this reason, due to the pressure by the measurement medium applied to the second surface (33f) which is the surface opposite to the first surface (33c) in contact with the mold IC among the pressure seal portions, the pressure seal portion The pressure is applied to the mold IC (outer wall surface thereof). Thereby, since a strong pressure is applied to the mold IC (outer wall surface thereof), a gap is hardly generated between the pressure seal portion and the mold IC. Therefore, it is difficult for the pressure medium to enter the gap formed between the pressure seal portion and the mold IC, and it is difficult for the pressure detection accuracy to deteriorate due to pressure leakage.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure showing the section composition of the pressure sensor concerning a 1st embodiment of the present invention. It is the figure which expanded the peripheral part of a pressure seal part among the pressure sensors shown in FIG. The length x from one end of the first surface of the pressure seal portion to the other end is taken as the horizontal axis, and the pressure P by the pressure seal portion applied to the mold IC is taken as the vertical axis, from x, P, and the first surface It is a figure which shows each relationship of the thickness t to a 2nd surface. It is a perspective view which shows the structure (The part except a pressure seal part among the coating parts of a connector case, only a part equivalent to a mold IC, a pressure seal part) of the Example which concerns on the pressure sensor which concerns on 1st Embodiment. It is the figure which showed the plane structure of the part shown in FIG. 4 about the Example which concerns on the pressure sensor which concerns on 1st Embodiment of this invention. It is the figure which showed the cross-sectional structure of the part shown in FIG. 4 about the Example which concerns on the pressure sensor which concerns on 1st Embodiment of this invention. FIG. 4 shows variables and levels when an FEM analysis is performed using the portion shown in FIG. 4 for an example of the pressure sensor according to the first embodiment of the present invention. The Example which concerns on the pressure sensor which concerns on 1st Embodiment of this invention shows the analysis result when the level shown in FIG. 7 is set and the FEM analysis is performed using the part shown in FIG. It is the figure which expanded the peripheral part of the pressure seal part in the pressure sensor which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A pressure sensor 1 according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the pressure sensor 1 according to the first embodiment includes a mold IC 2 having a configuration in which a sensor chip 21 is sealed with a mold resin 22, a connector case 3 for sealing the mold IC 2, and a connector case 3. And a connected housing 4. The pressure sensor 1 is used, for example, for detecting the pressure of air sucked into the engine (intake pressure), the pressure of fuel supplied to the engine, and the like.

  The mold IC 2 is obtained by integrating the sensor chip 21 with the mold resin 22. As shown in FIG. 1, the mold IC 2 includes a sensor chip 21 having a pressure-sensitive element portion that senses pressure, a lead frame 23, and a mold resin 22 that seals the sensor chip 21 while exposing the pressure-sensitive element portion. It is set as the structure which has. As shown in FIG. 1, the mold IC 2 is sealed by the connector case 3 such that a part including the pressure sensitive element portion of the mold IC 2 protrudes from one surface 33 a of the connector case 3 described later. Hereinafter, a surface of the mold IC 2 that protrudes from the one surface 33a is referred to as an outer wall surface 22b.

  The sensor chip 21 is disposed in the opening 22a formed in the mold resin 22, is fixed to the mold resin 22 with an adhesive or the like, and detects the pressure of the pressure medium introduced into the opening 22a. It has become. The pressure sensitive element portion provided in the sensor chip 21 is configured by a diaphragm or the like.

  The mold resin 22 is formed of a thermosetting resin such as an epoxy resin, and covers most of the lead frame 23 and is sealed. Although not shown, the mold resin 22 incorporates a signal processing circuit IC as an electronic component.

  The lead frame 23 is electrically connected to the sensor chip 21 via a bonding wire or the like, and one end side portion is exposed from the mold resin 22.

  The connector case 3 is formed integrally with the mold IC 2 and is made of a thermoplastic resin such as PPS (polyphenylene sulfide) or PBT (polybutylene terephthalate). The connector case 3 is configured by integrally forming a connector portion 31 to which an external connector is connected and a covering portion 33 that covers the terminal 32 and the molded IC 2.

  As shown in FIG. 1, the connector case 3 has one surface 33a in the covering portion 33, and a part including the pressure sensitive element portion of the mold IC2 protrudes from the one surface 33a to seal the mold IC2. .

  The connector portion 31 is a portion that outputs a sensor signal to the outside, and has a hollow cylindrical shape inside, and the one end side portion 32a of the terminal 32 is disposed inside the connector portion 31. The other end portion 32b of the terminal 32 is electrically connected to the lead frame 23 of the mold IC2.

  The covering portion 33 covers the terminal 32 connected to the lead frame 23 and the portion of the mold IC 2 on the connector portion 31 side, and exposes the portion of the mold IC 2 on the sensor chip 21 side.

  The connector case 3 is configured to have a pressure seal portion 33b that protrudes from the one surface 33a along the outer wall surface 22b of the mold IC2. Here, the pressure seal portion 33 b is integrally formed of the same material as that of the covering portion 33. As shown in FIG. 1, the pressure seal portion 33b according to the present embodiment has a quadrangular cross section. Further, the pressure seal portion 33b according to the present embodiment is formed over the entire circumference so as to surround the mold IC2.

  The pressure seal portion 33b is perpendicular to the outer wall surface 22b of the mold IC 2 (see the alternate long and short dash line B in FIG. 1. When the outer wall surface 22b is a curved surface, the “vertical direction” is rephrased as the “normal direction”. ) Is sandwiched between the mold IC 2 and the pressure chamber 6. As shown in FIG. 2, in the pressure sensor 1 according to the present embodiment, the measurement is applied to the second surface 33f, which is the surface opposite to the first surface 33c in contact with the mold IC2 in the pressure seal portion 33b. Due to the pressure by the medium, the pressure is applied to the outer wall surface 22b of the mold IC2. That is, in the pressure sensor 1 according to the present embodiment, a strong pressure is applied to the outer wall surface 22b of the mold IC 2 because the pressure seal portion 33b is sandwiched as described above.

Here, as shown in FIG. 2, the magnitude of the pressure by the measurement medium applied to the second surface 33f is P ₀ , and the magnitude of the pressure by the pressure seal portion 33b applied to the mold IC 2 by the pressure. Let P be the size. In addition, the end of the pressure seal portion 33b on the side close to the one surface 33a is one end 33d, the end on the far side is the other end 33e, and the length from the one end 33d to the other end 33e of the first surface 33c is x. The thickness from the first surface 33c to the second surface 33f is t.

At this time, the pressure seal portion 33b according to the present embodiment, it is desirable to be configured to P increases, ideally P is desired to be configured to match the P _0. That is, the pressure sensor 1 according to the present embodiment is configured such that a pressure (P) close to the pressure (P ₀ ) applied to the second surface 33f by the measurement medium is applied to the mold IC 2 (the outer wall surface 22b). It is desirable. The larger P is, the stronger the pressure seal portion 33b is pressed against the mold IC2, and it becomes difficult for a gap to be formed between the pressure seal portion 33b and the mold IC2. As a result, it is difficult for the pressure medium to enter the gap formed between the pressure seal portion 33b and the mold IC 2, and it is difficult for the pressure detection accuracy to deteriorate due to pressure leakage.

Here, as shown in FIG. 3, P ₀ varies depending on the values of t and x. Therefore, in order to increase P, considering this, the pressure seal portion 33b may be configured to have a sufficiently large x corresponding to t. In order to increase P, the smaller the elastic modulus of the pressure seal portion 33b, the better. For example, the elastic modulus of the pressure seal portion 33b is lower at the operating environment temperature (for example, −30 to 120 ° C.). It is preferable that the structure be smaller than the elastic modulus of the mold IC2 (mold resin 22).

  The housing 4 is a metal case connected to the connector case 3. As shown in FIG. 1, the housing 4 introduces a pressure introduction hole 41 for introducing a measurement medium to be pressure-detected into a pressure chamber 6 to be described later, and the pressure medium to the pressure-sensitive element portion of the sensor chip 21. A pressure introduction passage 42 and a housing portion 43 for housing a part of the connector case 3 are provided. The pressure introduction passage 42 is configured as a hollow portion of the housing 4. The accommodating portion 43 is configured as an opening at a portion opposite to the pressure introducing passage 42. In the pressure sensor 1 according to the present embodiment, a pressure chamber 6 surrounded by the housing 4 and the mold IC 2 is formed inside the housing 4, and the pressure chamber 6 is surrounded by the pressure sensitive element portion of the sensor chip 21. Is formed. In the pressure sensor 1 according to the present embodiment, the interface between the mold IC 2 and the connector case 3 is exposed to the pressure chamber 6 (see symbol A in FIG. 1).

  The housing 4 is formed by caulking a part of the housing 4 (portion located in the covering portion 33 in the connector case 3) in a state where the portion on the mold IC 2 side of the connector case 3 is accommodated in the accommodating portion 43. 3 is connected. In the pressure sensor 1 according to the present embodiment, an O-ring 5 is interposed between the housing 4 and the connector case 3, and the housing 4 and the connector case 3 are sealed by the O-ring 5.

  Here, FIGS. 4 to 8 show an example of analysis by FEM (Finite Element Method) as an example. In this example, assuming the covering portion 33 of the connector case 3, the objects shown in FIGS. 4 to 6 were set and analyzed. As shown in FIG. 4, this object includes a cylindrical portion having one surface 33a (corresponding to a portion excluding the pressure seal portion 33b in the covering portion 33) and a quadrangular prism portion protruding from the one surface 33a (corresponding to the mold IC2). And a seal portion (corresponding to the pressure seal portion 33b) formed over the entire circumference so as to surround the quadrangular prism portion. In the following, for convenience, these portions are simply referred to as “portions of the covering portion 33 excluding the pressure seal portion 33b”, “mold IC2”, and “pressure seal portion 33b”. In addition, as a parameter (internal dimension) indicating the shape of the pressure seal portion 33b, a which is the length in the horizontal direction and b which is the length in the vertical direction is set in FIG.

  Of the parts constituting the object, the elastic part of the covering part 33 excluding the pressure seal part 33b and the pressure seal part 33b have an elastic modulus of 8.9 GPa (Poisson's ratio is 0.35), and the elasticity of the mold IC2 The rate was 10.8 GPa (Poisson's ratio was 0.24).

  Then, as shown in FIG. 7, a / b, t, and x are set as variables, and 10 patterns as variations of these three variables (the level “Ref” in FIG. 7 is provided with a pressure seal portion 33b. Set).

In this way, P ₀ (pressure by the pressure seal portion 33b applied to the mold IC2) when P (the magnitude of pressure by the measurement medium) is set to 10 MPa by setting three variables and 10 pattern levels. The result shown in FIG. 8 was obtained. As a result, as is shown, the pressure seal portion 33b, by securing larger x corresponding to the t, may be configured to P is equal to P _0. There are some cases where P is larger than P ₀ , but this is presumed to be based on variations in measurement pressure, variations in the shape of the pressure seal portion 33b, and the like.

  Further, when the pressure seal portion 33b was not provided (level “Ref” in FIG. 8), P was a negative value. That is, in this case, pressure is applied in a direction in which the pressure seal portion 33b is separated from the mold IC2. For this reason, in this case, it is considered that the effect of making it difficult for the pressure medium to enter the gap formed between the pressure seal portion 33b and the mold IC 2 is not obtained.

As shown by the results of levels 7 to 9 in FIG. 8, it is assumed that not only x and t but also a / b contributes to the relationship between P and P _0. It is more desirable to consider not only x and t but also a / b.

  As described above, in the pressure sensor 1 according to the present embodiment, the connector case 3 includes the pressure seal portion 33b that protrudes from the one surface 33a along the outer wall surface 22b of the mold IC2. The pressure seal portion 33b is sandwiched between the mold IC 2 and the pressure chamber 6 in the direction perpendicular to the outer wall surface 22b of the mold IC 2.

  For this reason, in the pressure sensor 1 according to the present embodiment, the pressure by the measurement medium applied to the second surface 33f that is the surface on the opposite side of the first surface 33c that contacts the mold IC2 in the pressure seal portion 33b. As a result, the pressure seal portion 33b applies pressure to the mold IC 2 (the outer wall surface 22b). Thereby, since a strong pressure is applied to the mold IC 2 (the outer wall surface 22b), a gap is hardly generated between the pressure seal portion 33b and the mold IC 2. Therefore, in the pressure sensor 1 according to the present embodiment, it is difficult for the pressure medium to enter the gap generated between the pressure seal portion 33b and the mold IC 2, and the pressure detection accuracy is deteriorated due to pressure leakage. It becomes difficult to occur.

  Moreover, in the pressure sensor 1 according to the present embodiment, the pressure seal portion 33b is configured to be formed over the entire circumference so as to surround the mold IC2. For this reason, in the pressure sensor 1 according to the present embodiment, in particular, it is difficult for the pressure medium to enter the gap formed between the pressure seal portion 33b and the mold IC 2, and the pressure detection accuracy deteriorates due to the pressure leak. It becomes difficult to happen.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, in the first embodiment, the connector case 3 has a shape in which the cross section of the pressure seal portion 33b is a square. However, the shape of the pressure seal portion 33b is not limited to this. That is, for example, as shown in FIG. 9, in the pressure sensor 1 according to the first embodiment, the pressure seal portion 33 b may have a shape provided with a taper portion (see reference sign B in FIG. 9). Further, the seal portion 33b may have a shape provided with an R portion (curved surface).

  In the first embodiment, the connector case 3 is configured such that the pressure seal portion 33b is formed over the entire circumference so as to surround the mold IC2. However, the shape of the pressure seal portion 33b is not limited to this. That is, for example, in the pressure sensor 1 according to the first embodiment, the pressure seal portion 33b may be formed only on a part of the entire circumference surrounding the mold IC2.

2 Mold IC
21 Sensor chip 22 Mold resin 3 Connector case 33 Cover part of connector case 33b Pressure seal part of connector case 4 Housing 6 Pressure chamber

Claims (4)

Mold IC (2) having a configuration including a sensor chip (21) having a pressure-sensitive element portion for sensing pressure and a mold resin (22) for sealing the sensor chip while exposing the pressure-sensitive element portion. When,
A connector case (3) that has one surface (33a), projects a part including the pressure-sensitive element portion of the mold IC from the one surface, and seals the mold IC;
A pressure chamber (6) connected to the connector case to form a pressure chamber (6) around the pressure-sensitive element portion, and a pressure introducing hole (41) for introducing a measurement medium to be pressure-detected into the pressure chamber. A housing (4) configured to have,
A pressure sensor configured such that an interface between the mold IC and the connector case is exposed to the pressure chamber;
The one surface is a contact surface in contact with the housing on the side of the connector case from which the molded IC protrudes,
The mold IC has an outer wall surface (22b) protruding from the one surface,
The connector case has a pressure seal portion (33b) projected from the one surface along the outer wall surface,
The pressure sensor, wherein the pressure seal portion is sandwiched between the mold IC and the pressure chamber in a direction perpendicular to the outer wall surface.   The pressure sensor according to claim 1, wherein the pressure seal portion is formed over the entire circumference so as to surround the mold IC. The thickness from the first surface (33c) in contact with the outer wall surface of the pressure seal portion to the second surface (33f) opposite to the first surface is t, and t is 0.5 mm to 2.5 mm. The pressure sensor according to claim 1 or 2, which is within a range. A portion of the mold IC that protrudes from the connector case is formed into a quadrangular prism shape, and the pressure seal portion is seen from the mold IC when viewed from the direction in which the mold IC protrudes from the connector case. The variable represented by a / b is in the range of 1 to 3, where a is the length of one side of the inscribed outline and b is the length of the other side adjacent to the one side. The pressure sensor according to any one of the above.

Images