JP2014232024A - Physical quantity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of cracks in a sealant layer.SOLUTION: It has been found that in a region of a sealant layer 3 in which region a thermal expansion amount is relatively large in a terminal protruding direction (hereinafter, "high thermal expansion region"), a sealant layer thickness t1 when a heat stress is applied (i.e., at a high temperature) is far larger than a sealant layer thickness t0 at a normal temperature. As a result, a stress of a region Z in contact with a terminal 4 and a sensor chip 2 is higher, resulting in occurrence of cracks. Considering these, a protrusion 12 is provided in a region of a case 1 which region overlaps the high thermal expansion region so as to make the sealant layer thinner in the high thermal expansion region and reduce the thermal expansion amount of the thermal expansion region in the terminal protruding direction. This can reduce the stress of the region Z in contact with the terminal 4 and the sensor chip 2 in the high thermal expansion region and prevent occurrence of cracks in the sealant layer 3.

Description

  The present invention relates to a physical quantity sensor that detects a physical quantity and outputs a sensor signal corresponding to the detected physical quantity.

  Conventionally, a physical quantity sensor has been proposed in which a sensor chip that outputs a sensor signal corresponding to a physical quantity and a terminal held in the case are electrically connected, and the gap between the case and the terminal is sealed with a sealant layer (For example, refer to Patent Document 1).

JP 2006-23110 A

  However, there is a problem that cracks are generated at portions of the sealant layer that are in contact with the terminal and the sensor chip, and as a result, the gap between the case and the terminal cannot be reliably sealed.

  An object of this invention is to prevent generation | occurrence | production of the crack of a sealing agent layer in view of the said point.

  Here, the cause of occurrence of cracks in the sealant layer was examined. The examination result will be described with reference to FIG.

  Here, the direction in which the terminal 90 protrudes from the case 91 (the vertical direction in FIG. 5) is the terminal protruding direction, and the dimension of the sealing agent layer 92 in the terminal protruding direction is the sealing agent layer thickness.

  The amount of thermal expansion in the terminal protruding direction in the sealant layer 92 varies depending on the region, and in the region where the amount of thermal expansion in the terminal protruding direction is relatively large, the sealant layer thickness t1 when a thermal stress is applied (that is, at a high temperature). Is significantly larger than the sealant layer thickness t0 at normal temperature. For this reason, it was found that in the sealant layer 92 in the region where the thermal expansion amount in the terminal protruding direction is relatively large, the stress at the part Z in contact with the terminal 90 and the sensor chip 93 is increased and cracks are generated.

  The present invention has been made on the basis of the above examination results, and in order to achieve the above object, in the invention according to claim 1, a recess (11) having a bottom wall surface (111) and a peripheral wall surface (112) is formed. The case (1), the sensor part (2) that is mounted on the bottom wall surface and outputs a sensor signal corresponding to the physical quantity, and is held by the case, and one end part projects from the bottom wall surface into the recess. A terminal (4) that is electrically connected to the terminal, and a sealant layer (3) that is filled with a sealant from the bottom wall surface to the middle part of the peripheral wall surface and seals the gap between the case and the terminal. The direction protruding from the bottom wall surface into the recess is the terminal protruding direction, the dimension of the terminal protruding direction in the sealant layer is the thickness of the sealant layer, and the amount of thermal expansion in the terminal protruding direction in the sealant layer is When the region that becomes relatively large is a large thermal expansion region, the case includes a protrusion (12) that protrudes from the bottom wall surface into the recess to adjust the thickness of the sealant layer, and the protrusion is in the terminal protruding direction. When it sees along, it is arrange | positioned in the area | region which overlaps with a thermal expansion large area | region.

  According to this, the thickness of the sealant layer in the large thermal expansion region is reduced by providing the protrusion, and the amount of thermal expansion in the terminal protruding direction of the sealant layer in the large thermal expansion region can be reduced. Generation of cracks in the agent layer can be prevented.

  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 sectional drawing which shows the physical quantity sensor which concerns on one Embodiment of this invention. It is a bottom view which shows the state before sealing agent layer formation in the sensor of FIG. It is a bottom view which shows the state after sealing agent layer formation in the sensor of FIG. (A) is AA sectional drawing of FIG. 3 which shows the state of the sealing agent layer at the time of normal temperature, (b) is AA sectional drawing of FIG. 3 which shows the state of the sealing agent layer at the time of high temperature. (A) is sectional drawing of the principal part which shows the state of the sealing agent layer in the conventional sensor at the time of normal temperature, (b) is sectional drawing of the principal part which shows the state of the sealing agent layer in the conventional sensor at the time of high temperature.

  An embodiment of the present invention will be described. The physical quantity sensor of the present embodiment is mounted on an automobile, for example, and can be applied to a pressure sensor that detects the pressure of refrigerant in an air conditioner or the pressure of lubricating oil in an automobile engine or drive system.

  As shown in FIGS. 1 to 3, the case 1 is made by molding a resin such as PPS (polyphenylene sulfide) and has a substantially cylindrical shape. A recess 11 having a bottom wall surface 111 and a peripheral wall surface 112 is formed on one end side (the lower side in FIG. 1) of the case 1. Further, on one end side of the case 1, a protruding portion 12 (detailed later) that protrudes from the bottom wall surface 111 into the recess 11 and adjusts the thickness of the sealant layer 3 described later is formed.

  A sensor chip 2 as a sensor unit is disposed in the recess 11. The sensor chip 2 is a semiconductor diaphragm type that has a diaphragm as a pressure receiving surface, converts the pressure received by the diaphragm into an electrical signal, and outputs the electrical signal as a sensor signal.

  The sensor chip 2 is integrated with a pedestal 21 made of glass or the like by anodic bonding or the like. The sensor chip 2 integrated with the pedestal 21 is mounted on the case 1 by bonding the pedestal 21 to the bottom wall surface 111 of the recess 11 with an adhesive.

  The case 1 is provided with a plurality of metal plate-like terminals 4 for electrically connecting the sensor chip 2 to an external circuit or the like. The terminal 4 is made of a material obtained by performing a plating process such as Ni plating on brass. The terminal 4 is held by the case 1 by insert molding the case 1 using the terminal 4 as an insert.

  An end on one end side (the lower end side in FIG. 1) of each terminal 4 protrudes into the recess 11 from the bottom wall surface 111 of the recess 11 around the mounting area of the sensor chip 2.

  And the front end surface of the protrusion part of each terminal 4 and the sensor chip 2 are connected and electrically connected through bonding wires 5 made of Au (gold), Al (aluminum), etc. formed by wire bonding. Yes.

  Further, around the protruding portion of each terminal 4, the sealing agent layer 3 is provided by filling the sealing agent from the bottom wall surface 111 to the middle portion of the peripheral wall surface 112. The sealing agent layer 3 seals the gap between the case 1 and the terminal 4. The sealing agent is moisture-curing silicone.

  The other end side (upper side in FIG. 1) of the case 1 is connected to the other end side of the terminal 4 opposite to the projecting portion via an external wiring member (not shown) such as a wire harness. It is the connection part 13 for electrically connecting to (ECU etc. of a vehicle). Thus, signal transmission between the sensor chip 2 and the outside is performed via the bonding wire 5 and the terminal 4.

  The housing 6 assembled to one end side of the case 1 is made of a metal material such as stainless steel (SUS). The housing 6 has an opening 61 on one end side (upper end side in FIG. 1), and a pressure introduction hole 62 into which the pressure medium is introduced from the outside on the other end side (lower end side in FIG. 1). Have. This pressure medium is, for example, the above-described air conditioner refrigerant or automobile lubricating oil.

  Further, on the outer surface on the other end side of the housing 6, there is formed a screw portion 63 for fixing the pressure sensor to an appropriate location of the automobile, for example, a location such as a refrigerant pipe of an air conditioner or a lubricating oil pipe of the automobile.

  A metal diaphragm 7 is provided on one end side of the housing 6. The metal diaphragm 7 is fixed to the housing 6 by welding or the like through a metal ring weld 8.

  The housing 6 is assembled to the case 1 so as to cover the recess 11 in a state where one end side (the lower end side in FIG. 1) of the case 1 is inserted into the opening 61. The housing 6 is fixed to the case 1 by caulking the end portion on one end side thereof.

  An annular groove 14 is formed on one end side of the case 1, and an O-ring 9 for sealing the space between the case 1 and the ring weld 8 is disposed in the groove 14.

  The recess 11 is filled with oil so as to cover the sensor chip 2, the terminal 4, and the bonding wire 5. This oil is made of fluorine oil or the like and functions mainly as a pressure transmission medium.

  A basic pressure detection operation of the physical quantity sensor will be described. The physical quantity sensor is attached to an appropriate position of the vehicle via, for example, a screw part 63 of the housing 6. Then, an external pressure medium (such as the above-described air conditioner refrigerant or automobile lubricating oil) is introduced into the physical quantity sensor through the pressure introduction hole 62 of the housing 6.

  Then, the introduced pressure is applied to the diaphragm which is the pressure receiving surface of the sensor chip 2. Then, an electrical signal corresponding to the applied pressure is output from the sensor chip 2 as a sensor signal. This sensor signal is transmitted from the sensor chip 2 to the external circuit via the bonding wire 5 and the terminal 4. The above is the basic pressure detection operation in the physical quantity sensor.

  Next, the protrusion 12 will be described in detail with reference to FIGS. Here, the direction in which the terminal 4 projects from the bottom wall surface 111 into the recess 11 is defined as the terminal projecting direction, the dimension of the terminal projecting direction in the sealing agent layer 3 is the sealing agent layer thickness, and the direction in the terminal projecting direction in the sealing agent layer 3 is A region where the thermal expansion amount is relatively large is defined as a large thermal expansion amount region. In FIG. 3, the sealing agent layer 3 is indicated by oblique lines in order to clarify the range of the sealing agent layer 3.

  As shown in FIG. 3, the sealant layer 3 includes a gap region between the terminal 4 and the peripheral wall surface 112 (hereinafter referred to as a first gap region), and a gap region between the sensor chip 2 and the peripheral wall surface 112 (hereinafter referred to as “first gap region”). , And a second gap area) and a gap area between the terminal 4 and the sensor chip 2 (hereinafter referred to as a third gap area).

  The first gap area is a gap area between the terminal 4 and the peripheral wall surface 112 (hereinafter referred to as a narrow first gap area) and the terminal 4 and the peripheral wall surface 112. There is a gap area (hereinafter referred to as a large first gap area) having a relatively wide gap dimension.

  In addition, the gap dimension between the sensor chip 2 and the peripheral wall surface 112 in the second gap area is relatively narrower than the gap dimension in the wide first gap area.

  Further, the gap dimension between the terminal 4 and the sensor chip 2 in the third gap area is relatively narrower than the gap dimension in the large first gap area.

  Here, in the gap region where the gap size is narrow and the gap region adjacent to the gap region, the thickness of the sealing agent layer is increased by the surface tension. For this reason, when the protrusion 12 is not provided, a region where a plurality of gap regions with relatively narrow gap dimensions are connected is a large thermal expansion region. In the present embodiment, the region where the first gap region, the second gap region, and the third gap region with a small width connect has the largest amount of thermal expansion in the terminal protruding direction.

  Therefore, in the present embodiment, the first gap region, the second gap region, and the third gap region having a small width are connected to the region overlapping the large thermal expansion region when viewed along the terminal protruding direction. The projecting portions 12 are arranged at two locations in the area to be performed.

  By providing this projection 12, the thickness of the sealant layer 3 in the region where the first gap region, the second gap region, and the third gap region having small widths are connected is reduced, and the sealant layer 3 in that region is reduced. The amount of thermal expansion in the terminal protruding direction is reduced. That is, in the region where the first gap region, the second gap region, and the third gap region having a small width are connected, the amount of increase in the sealant layer thickness t1 at the high temperature with respect to the sealant layer thickness t0 at the normal temperature is small. Become.

  For this reason, in the sealing agent layer 3 in the region where the first narrow gap region, the second gap region, and the third gap region are connected, the stress at the portion Z that contacts the terminal 4 or the sensor chip 2 is reduced. The generation of cracks is prevented.

(Other embodiments)
In the above embodiment, a pressure sensor that detects pressure is shown as a physical quantity sensor. However, the present invention can also be applied to a sensor that detects a physical quantity other than pressure.

  In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably.

  Further, in the above-described embodiment, it is needless to say that elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where the element is clearly considered to be essential in principle. .

  Further, in the above embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is particularly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to a specific number except for cases.

  In the above embodiment, when referring to the shape, positional relationship, etc. of components, the shape, position, etc., unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to relationships.

1 Case 2 Sensor chip (sensor part)
3 Sealant layer 4 Terminal 11 Recess 12 Protrusion 111 Bottom wall 112 Surrounding wall

Claims (6)

A case (1) formed with a recess (11) having a bottom wall surface (111) and a peripheral wall surface (112);
A sensor unit (2) mounted on the bottom wall surface and outputting a sensor signal according to a physical quantity;
A terminal (4) which is held by the case and has one end protruding from the bottom wall surface into the recess and electrically connected to the sensor unit;
A sealing agent layer (3) that is filled with a sealing agent from the bottom wall surface to an intermediate portion of the peripheral wall surface and seals a gap between the case and the terminal;
The direction in which the terminal projects from the bottom wall surface into the recess is the terminal projecting direction, the dimension of the terminal projecting direction in the sealant layer is the thickness of the sealant layer, and the heat in the terminal projecting direction in the sealant layer When the region where the expansion amount is relatively large is the large thermal expansion region,
The case includes a protrusion (12) that protrudes from the bottom wall surface into the recess to adjust the thickness of the sealant layer,
The physical quantity sensor, wherein the protrusion is disposed in a region overlapping the large thermal expansion region when viewed along the terminal protruding direction.   The thermal expansion large region is a gap region between the terminal and the peripheral wall surface, a gap region between the sensor unit and the peripheral wall surface, and a gap region between the terminal and the sensor unit, The physical quantity sensor according to claim 1, wherein a plurality of relatively narrow gap regions are connected to each other.   The physical quantity sensor according to claim 2, wherein the large thermal expansion region is a region where three relatively narrow gap regions are connected. One sensor part is provided,
A plurality of the terminals;
The physical quantity sensor according to claim 1, wherein the plurality of terminals are arranged around the sensor unit.   The physical quantity sensor according to claim 1, wherein the sealant is silicone.   The physical quantity sensor according to claim 1, wherein the case is insert-molded using the terminal as an insert.

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