Abstract:
A pressure detecting apparatus has a pressure detecting device that converts a strain caused by a stress exerted thereto to an electrical signal, and outputs the converted electrical signal. The apparatus has a housing base including a housing recess that houses the pressure detecting device therein, and a connecting material interposed between the pressure detecting device and the housing recess. The connecting material connects the pressure detecting device and the housing recess with a tensile elongation percentage of about 400% or higher. The pressure detecting apparatus facilitates preventing thermal stress from adversely affecting the detection performance thereof, and produces excellent thermal response.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT  
       [0001]     The present invention relates to a pressure detecting apparatus that converts the pressure detected thereby to an electrical signal and outputs the converted electrical signal. Specifically, the present invention relates also to a pressure detecting apparatus that exhibits excellent thermal response.  
         [0002]     Usually, the semiconductor pressure sensor chip that employs the so-called piezoresistance effects has been used for a pressure detecting apparatus for measuring the intake air pressure on the air intake side of an engine in the electronic controlled fuel injection apparatus for automobiles. Since the operational principles of the pressure detecting apparatus that employs the semiconductor pressure sensor chip as described above are well known, the detailed descriptions thereof are omitted. The pressure detecting apparatus includes a bridge circuit consisting of semiconductor strain gauges formed on a diaphragm made of a material that exhibits piezoresistance effects such as single crystalline silicon. A pressure is detected by taking out the gauge resistance changes, caused in the semiconductor strain gauges by the diaphragm distortion, from the bridge circuit in the form of an electrical signal.  
         [0003]     Now the pressure detecting apparatus briefly described above will be explained below with reference to  FIGS. 5 and 6 .  FIG. 5  is a cross-sectional view of a conventional pressure detecting apparatus.  FIG. 6  is an expanded cross-sectional view showing a part of the conventional pressure detecting apparatus shown in  FIG. 5 . Referring now to these drawings, a pressure detecting apparatus  500  includes a pressure detecting device  501 , that is a semiconductor pressure sensor chip, mounted on a housing base  502  of a resin molding, that is a package casing of pressure detecting apparatus  500 . A housing recess  503  for housing pressure detecting device  501  therein is formed in housing base  502 .  
         [0004]     Pressure detecting device  501  is mounted on housing base  502  in such a configuration, in which pressure detecting device  501  is bonded by die-bonding with an adhesive  504  to housing recess  503  formed in housing base  502 . Pressure detecting device  501  is electrically connected, via bonding wires  506 , to lead terminals (lead frames)  505  integrated into housing base  502  by insertion molding such that lead terminals  505  are extending through housing base  502 .  
         [0005]     For reducing the stress exerted from housing base  502  in the structure described above, pressure detecting device  501  is bonded to a pedestal  507  made of glass by the anodic bonding technique known to those skilled in the art such that a vacuum reference space is formed between pressure detecting device  501  and glass pedestal  507 . A gel protecting material  508  covers the surface  501   a  of pressure detecting device  501  and adheres pressure detecting device  501  to housing base  502  in such a manner that gel protecting material  508  contains bonding wires  506  therein. Protecting material  508  protects pressure detecting device  501  from the contaminants contained in the not-shown medium, the pressure thereof is to be measured with pressure detecting apparatus  500 , and transmits the medium pressure to pressure detecting device  501 . Protecting material  508  is also disposed between the side face of detecting device  501  and the side face of housing recess  503 .  
         [0006]     A housing cover  510  formed of a molded resin material includes a tube-shaped pressure transmitting section  509  having a cylindrical inner surface  509   a  (cf.  FIG. 5 ). Housing cover  510  is mounted on and fixed, with an adhesive, to the opening side end portion of housing recess  503  in housing base  502  such that a pressure detecting space  511  consisting of a space connected to pressure transmitting section  509  is formed (cf.  FIG. 5 ). The medium pressure to be measured is transmitted to pressure detecting space  511  through pressure transmitting section  509  in housing cover  510 . Pressure detecting apparatus  500  detects the pressure difference between the transmitted medium pressure to be measured and the vacuum reference room pressure as a pressure change, converts the detected pressure change to an electrical signal in pressure detecting device  501 , and outputs the converted electrical signal. Thus, the absolute medium pressure is measured.  
         [0007]     For meeting the various demands for pressure detecting apparatus  500  such as down-sizing of entire pressure detecting apparatus  500 , realization of very precise detection characteristics and realization of very high reliability, the opening size of housing recess  503  is optimized so that a clearance optimum for reducing the stress exerted from housing base  502  may be obtained between pressure detecting device  501  and housing base  502  (cf. Japanese Patent Publication No. 2003-247903).  
         [0008]     In pressure detecting apparatus  500  having the structure as described above, the deformation of housing base  502  caused by an external stress exerted from housing cover  510  or by a thermal stress due to a severe measurement environment associating drastic temperature changes adversely affects the detection performances of pressure detecting device  501 , impairing the thermal response of pressure detecting apparatus  500 .  
         [0009]     The thermal response is one of the evaluation items for performances tests indicating the detection performances change caused by the environmental temperature change, e.g. from a high temperature to a low temperature. In the pressure detecting apparatus, the thermal response thereof is not good, variations are caused between the initial detection performances and the detection performances after a temperature change is caused.  
         [0010]     If the loading amount of adhesive  504  for mounting pressure detecting device  501  on housing base  502  is too large, adhesive  504 , which has bulged out of the gap between the bottom surface  503   a  of housing recess  503  and the bottom surface  507   a  of pedestal  507  creeps up the clearance between pressure detecting device  501  and housing base  502 , that is, the gap between the side face  507   b  of pedestal  507  and the side face  503   b  of housing recess  503  as shown in  FIG. 6 . Therefore, the stress caused, for example, by the deformation of housing base  502  in the direction indicated by the outline arrows in  FIG. 6  directly affects the detection performances of pressure detecting device  501 , impairing the thermal response of pressure detecting apparatus  500 .  
         [0011]     In view of the foregoing, it would be desirable to provide a pressure detecting apparatus that facilitates reducing the adverse effects of thermal stress on the detection performances to the extreme thereof and exhibits excellent thermal response.  
         [0012]     Further objects and advantages of the invention will be apparent from the following description of the invention and the associated drawings.  
       SUMMARY OF THE INVENTION  
       [0013]     According to one embodiment of the invention, there is provided a pressure detecting apparatus including a pressure detecting means, the pressure detecting means converting the strain caused by the stress exerted thereto to an electrical signal, the pressure detecting means outputting the converted electrical signal; a base means including a housing means, the housing means housing the pressure detecting means therein; and a connecting means interposed between the pressure detecting means and the housing means, the connecting means connecting the pressure detecting means and the housing means at a tensile elongation percentage of 400% or higher.  
         [0014]     According to one aspect of the invention, the pressure detecting means is made of a semiconductor.  
         [0015]     According to another aspect of the invention, the base means is formed of a resin molding.  
         [0016]     According to another aspect of the invention, the connecting means is made of a silicone resin adhesive.  
         [0017]     According to another aspect of the invention, the connecting means is formed such that the distance between the bonding plane of the pressure detecting means and the bonding plane of the housing means is from 30 μm to 100 μm.  
         [0018]     Since the pressure detecting means and the base means are connected and fixed to each other with the connecting means exhibiting an elongation percentage of about 400% or higher, the pressure detecting apparatus according to the invention that facilitates absorbing the exerted stress based on the excellent elongation characteristics exhibits excellent thermal response.  
         [0019]     The pressure detecting apparatus according to the invention that exhibits excellent thermal response facilitates realizing a structure immune to temperature changes caused in the measurement environment and obtaining measurement results with very high reproducibility. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is a top plan view of a pressure detecting apparatus according to a first embodiment of the invention.  
         [0021]      FIG. 2  is a cross-sectional view along the line segment  2 - 2 ′ in  FIG. 1 .  
         [0022]      FIG. 3A  is an expanded cross-sectional view of a part of  FIG. 2 .  
         [0023]      FIG. 3B  is a cross-sectional view showing a modification of the structure shown in  FIG. 3A .  
         [0024]      FIG. 4  shows a curve relating the output variation (%F.S.×10) caused by the thermal response shift with the tensile elongation percentage (%) of the connecting material.  
         [0025]      FIG. 5  is a cross-sectional view of a conventional pressure detecting apparatus.  
         [0026]      FIG. 6  is an expanded cross-sectional view showing a part of the conventional pressure detecting apparatus shown in  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]     Now the invention will be described in detail hereinafter with reference to the accompanied drawings which illustrate the preferred embodiments of the invention. In the descriptions of the embodiments and the drawings illustrating the embodiments, the same reference numbers are used to designate the same of like constituent elements and their duplicated explanations are omitted for the sake of simplicity.  
         [0028]      FIG. 1  is a top plan view of a pressure detecting apparatus according to a first embodiment of the invention.  FIG. 2  is a cross-sectional view along the line segment  2 - 2 ′ in  FIG. 1 .  FIG. 3A  is an expanded cross-sectional view of a part of  FIG. 2 .  FIG. 3B  is a cross-sectional view showing a modification of the structure shown in  FIG. 3A . In the following, the invention will be described with reference to  FIGS. 1 through 3 B as far as any specific explanation is not made and the reference numbers designating the constituent elements not illustrated in the drawings will not be described in the drawings.  
         [0029]     Referring now to  FIGS. 1 through 3 A, the pressure detecting apparatus  100  according to the first embodiment includes a pressure detecting device  110 , a housing base  120  housing pressure detecting device  110  therein, and a housing cover  130  mounted on housing base  120 . Pressure detecting device  110 , housing base  120  and housing cover  130  are arranged in a coaxial manner with the centers thereof aligned on a central axis C.  
         [0030]     Pressure detecting device  110  includes a semiconductor substrate  111  made of silicon and a pedestal  112  made of glass and bonded to semiconductor substrate  111 . Semiconductor substrate  111  is bonded to pedestal  112  by the anodic bonding technique known to those skilled in the art to reduce the stress exerted from housing base  120 . Semiconductor substrate  111  has a recess  111   c  in the bottom surface  111   b  on the side of the bonding surface  112   a  of pedestal  112 . Pressure detecting device  110  uses recess  111   c  of semiconductor substrate  111  closed by bonding surface  112   a  of pedestal  112  for a reference pressure chamber  113 . Pedestal  112  is a hexahedron made of heat-resisting glass and having rectangular cross sections.  
         [0031]     A diaphragm  114  is formed in the portion of pressure detecting device  110  corresponding to reference pressure chamber  113  of semiconductor substrate  111 . Not-shown strain gauges are formed on diaphragm  114  and a not-shown bridge circuit is formed by connecting the strain gauges in the form of a bridge. A not shown amplifier circuit connected to the bridge circuit is formed in semiconductor substrate  111 .  
         [0032]     A strain is caused in pressure detecting device  110  when a pressure is exerted to diaphragm  114  of semiconductor substrate  111 . An electrical signal is outputted from the bridge circuit in the form of a voltage caused by the stress. The electrical signal is amplified by the not shown amplifier circuit and the amplified electrical signal is outputted from the amplifier circuit. Pressure detecting device  110  that has the structure as described above and works as described above is an absolute-pressure-type one that employs strain gauges. Alternatively, pressure detecting device  110  may be an electrostatic-capacitance-type one.  
         [0033]     Housing base  120  is a resin molding material made of polyphenylene sulfide (hereinafter referred to as “PPS”) and such a thermoplastic resin. Housing base  120  includes a housing recess  121  for housing pressure detecting device  110  therein. Housing base  120  includes also a space on the opening side of housing recess  121 . The space on the opening side of housing recess  121  constitutes a part of the pressure detecting chamber described later. Alternatively, housing base  120  may be made of a heat-resisting thermoplastic resin other than PPS with no associated problem.  
         [0034]     Pressure detecting device  110  is housed in housing recess  121  of housing base  120  in such a manner that pressure detecting device  110  is connected and fixed to housing recess  121  via a connecting material  129 . In detail, pressure detecting device  110  is connected and fixed to housing base  120  with connecting material  129  interposed between the bottom surface  121   a  of housing recess  121  and the bottom surface  112   b  of pedestal  112 , on which pressure detecting device  110  is mounted. Thus, pressure detecting device  110  is fixedly supported by housing base  120 .  
         [0035]     Connecting material  129  is a resin material made of a silicone resin adhesive and such a silicone resin. In detail, connecting material  129  is made of a silicone resin adhesive (X32-2170AB supplied from Shin-Etsu Chemical Co., Ltd.). Connecting material  129  exhibits a tensile elongation percentage of 400% or higher. Connecting material  129  is formed such that the thickness thereof (the distance between bottom surface  121   a  of housing recess  121  and bottom surface  112   b  of pedestal  112 ) is from 30 μm to 100 μm.  
         [0036]     Referring now to  FIG. 3B , protrusions  150  maybe formed on bottom surface  121   a  of housing recess  121  to adjust the thickness of connecting material  129  with no associated problem. Protrusions  150  are formed in such an arrangement that the tips of protrusions  150  are in contact with the four corners of bottom surface  112   b  of pedestal  112 , to which pressure detecting device  110  is fixed. Alternatively, protrusions  150  may be shaped with respective protruding stripes. Protrusions  150  are from 30 μm to 100 μm in height corresponding to the thickness of connecting material  129 . It is not always necessary for the tips of protrusions  150  to be in contact with bottom surface  112   b  of pedestal  112 . In other words, connecting material  129  may be interposed between pedestal  112  and the tip&#39;s of protrusions  150 . Connecting material  129  formed as described above facilitates absorbing the thermal stress so that the thermal stress may not be transmitted from housing base  120  to pressure detecting device  110  via connecting material  129  and effectively preventing thermal response delay from arising in pressure detecting apparatus  100 .  
         [0037]     Lead terminals  122  are integrated into housing base  120  by insertion molding such that lead terminals  122  are extending from the vicinity of the opening of housing recess  121  in the direction perpendicular to the central axis C. Lead terminals  122  are led outside housing base  120 . Each lead terminal  122  is a plate formed by punching a base alloy of nickel (Ni) and iron (Fe). Each lead terminal  122  includes a land section  123  arranged around the opening of housing recess  121  and a lead section  124  extended from land section  123  to the outside of housing base  120 . As shown in  FIG. 1 , eight lead sections  124  are exemplary disposed in pressure detecting apparatus  100 .  
         [0038]     Land section  123  on each lead terminal  122  is connected electrically, via bonding wires  125  made of aluminum (Al) or gold (Au), to the surface  111   a  of semiconductor substrate  111  connected and fixed to housing base  120 . Lead section  124  of each lead terminal  122  is connected to an external wiring material (not shown) outside housing base  120 . Although not illustrated, an internal circuit, connected to pressure detecting device  110  or land sections  123  of lead terminals  122  via bonding wires  125 , may be disposed in housing base  120  with no problem. The internal circuit adjusts the electrical signals outputted from pressure detecting device  110  and outputs the adjusted signals outside pressure detecting apparatus  100 .  
         [0039]     In the space formed on the opening side of housing recess  121  in housing base  120 , a protecting material  126  is formed in such a manner that protecting material  126  covers and seals the surface  111   a  of semiconductor substrate  111  together with bonding wires  125  and land sections  123  of lead terminals  122 . Protecting material  126  is made of a gel resin. Protecting material  126  is disposed to protect pressure detecting device  110 , bonding wires  125  and such constituent elements from contaminants and to transmit the pressure to be measured to pressure detecting device  110  without fail. It is preferable to dispose protecting material  126  also between the side face of housing recess  121  and the side face of pressure detecting device  110 .  
         [0040]     In the circumference portion of the opening side surface of housing base  120 , an insert-fitting groove  127  is formed. Housing cover  130  is mounted on housing base  120  with an insert-fitting protrusion  137  protruding from housing cover  130  made to fit into insert-fitting groove  127 . Housing cover  130  and housing base  120  are adhered and fixed to each other with a not shown adhesive filling insert-fitting groove  127 . Pressure detecting device  110  housed in housing base  120  is sealed and fixed to pressure detecting apparatus  100  by housing cover  130 .  
         [0041]     Housing cover  130  is a resin molding made of PPS in the same manner as housing base  120 . Housing cover  130  includes a flange section  131  and a cylindrical pressure transmitting section  132  standing vertically from the major surface  131   a  of flange section  131 . Housing cover  130  has a cross-sectional structure shaped with a letter T. A pressure transmitting hole  133  is bored through pressure transmitting section  132  concentrically with the central axis C. When housing cover  130  is bonded and fixed to housing base  120 , pressure transmitting hole  133  is connected to the space in housing base  120 . Housing cover  130  may be made of any heat-resisting resin other than PPS with no associated problem. A pressure detecting chamber  128  is the space in housing base  120  sectioned by flange section  131  of housing cover  130 .  
         [0042]     The pressure of the air, for example, which is a measurement environment, is transmitted to pressure detecting chamber  128  through pressure transmitting hole  133  bored through pressure transmitting section  132  of housing cover  130 . Diaphragm  114  is deformed by the difference between the air pressure transmitted to pressure detecting chamber  128  and the internal pressure of reference pressure chamber  113  in pressure detecting device  110 . An electrical signal is outputted from pressure detecting device  110  based on the strain caused by the deformation of diaphragm  114 . The electrical signal outputted from pressure detecting device  110  is outputted outside pressure detecting apparatus  100  via bonding wires  125 , the internal circuit, and lead terminals  122 . The pressure is measured by a not shown measuring apparatus disposed outside pressure detecting apparatus  100  based on the outputted electrical signal.  
         [0043]     Pressure detecting device  110  and housing base  120  are connected and fixed to each other by connecting material  129  exhibiting a tensile elongation percentage of about 400% or higher. Therefore, pressure detecting apparatus  100  facilitates obtaining a structure that transmits hardly any thermal stress caused from housing base  120  to pressure detecting device  110 , thereby effectively preventing thermal response delay from arising, and thus producing pressure measurement results with high reproducibility.  
         [0044]     Pressure detecting apparatus  100  as described above is manufactured in the following way. Dies are formed to fit housing base  120  and housing cover  130 . For forming housing base  120 , lead terminals  122  are fixed at the respective positions in the die for exclusive use, and housing base  120  is formed by loading a resin such as PPS into the die, and by cooling to solidify the resin. Housing cover  130  is formed by loading a resin such as PPS into the die for exclusive use and by cooling to solidify the resin. When PPS is used as the resin for housing base  120  and housing cover  130 , gases are liable to be caused in molding PPS and flashes are liable to be caused on the moldings. Therefore, if degassing is conducted and flashes are removed, housing base  120  and housing cover  130  will be manufactured very precisely.  
         [0045]     After forming housing base  120  and housing cover  130 , pressure detecting device  110  is connected and fixed to housing recess  121  of housing base  120  via connecting material  129 , the internal circuit is mounted, and lead terminals  122  are connected to pressure detecting device  110  and to the internal circuit via bonding wires  125 . The space on the opening side of housing recess  121  and the space between pressure detecting device  110  and housing recess  121  are covered with protecting material  126  made of a gel resin. And, housing cover  130  is mounted on and fixed to housing base  120 . Thus, pressure detecting apparatus  100  is manufactured.  
         [0046]     Pressure detecting apparatus  100 , which connects and fixes pressure detecting device  110  to housing base  120  with connecting material  129  exhibiting a tensile elongation percentage of about 400% or higher, realizes a structure that transmits hardly any thermal stress caused from housing base  120  to pressure detecting device  110 . The reasons for defining the tensile elongation percentage of connecting material  129  as described above will be explained below.  
         [0047]      FIG. 4  shows a curve relating the output variation (%F.S.×10) caused by the thermal response shift with the tensile elongation percentage (%) of connecting material  129 . The present inventors have conducted the following tests for defining the tensile elongation percentage of connecting material  129 . A strength characteristics measuring apparatus (EZ Test supplied from Shimadzu Corp.) is used for measuring the tensile elongation percentage. Tensile elongation percentage measuring tests are conducted on a silicone resin adhesive (X32-2170AB supplied from Shin-EtsuChemical Co., Ltd.) (hereinafter referred to as a “sample 1”) and a silicone resin adhesive (TSE 322  supplied from GE Toshiba Silicones Co., Ltd.) for comparison (hereinafter referred to as a “sample 2”).  
         [0048]     The samples 1 and 2 are 8 mm in width, 1.5 mm in height (thickness) and 50 mm in length. The distance between the jigs for fixing the sample to the measuring apparatus is set at 10 mm. The tensile tests are conducted at the pulling rate of 60 mm/min. The output variation caused by the thermal response shift and described in  FIG. 4  is the shift value of an output from the pressure detecting apparatus (detected output variation) caused when the pressure detecting apparatus, left in an environment of 130° C. for 1 hr, is returned to the room temperature environment (from 20° C. to 25° C.). The unit of the output variation caused by the thermal response shift is the percentage of an output voltage from pressure detecting apparatus  100  to the full scale (hereinafter referred to as the “F.S.”) of the output. Since the output voltage values obtained are so small that the output voltage values are multiplied by 10 and the corrected output voltage values are expressed.  
         [0049]     Since it is necessary for pressure detecting apparatus  100  and such on-vehicle equipment to be very precise, it is preferable for the output variation caused by the thermal response shift to be 0.125 (%F.S.) or less or 1.25 (%F.S.×10) or less in the 10 times expression. The tests are conducted based on the threshold for judging the output variations caused by the thermal response shift set at 1.25 (%F.S.×10). The elongation of connecting material  129  is the difference obtained by setting two gage marks (fixed points fixed by the fixing jigs), by measuring the distance L0 between the gage marks (the distance between the fixing jigs), by measuring the distance L1 between the gage marks after the tests, and by calculating L1-L0. The elongation percentage in % is calculated from the following formula (1). 
 
100×(L1-L0)/L0  (1) 
 
         [0050]     The tensile elongation percentage measuring tests conducted under the conditions as described above have revealed clear differences expressed by a correlation curve  401  shown in  FIG. 4  that connects the measurement results on the samples 1 and 2. Correlation curve  401  represents the correlation between the output variations and the elongation percentage in the measurement results on the samples 1 and 2. Correlation curve  401  indicates that as the elongation percentage becomes larger, the output variation becomes smaller, resulting in an improved thermal response. The lower right end point  402  on correlation curve  401  represents the results on the sample 1 and the upper left endpoint  403  on correlation curve  401  represents the results on the sample 2.  
         [0051]     In the sample 1, when the tensile elongation percentage is around 500%, the output variation caused by the thermal response shift is about 0.77 (%F.S.×10) as correlation curve  401  clearly indicates. In the sample 2, when the tensile elongation percentage is around 200%, the output variation caused by the thermal response shift is about 3.6 (%F.S.×10) as correlation curve  401  clearly indicates. For conducting the tests, the hardness (JIS A) is set at 20 for the sample 1 and at 17 for the sample 2. It has been clarified that if connecting material  129  is made of a material having a hardness of around 20, there will exist almost no correlation between the output variation caused by the thermal response shift and the hardness. Therefore, if connecting material  129  is made of a material having a hardness of around  20 , the correlation between the elongation characteristics of connecting material  129  and the output variation caused by the thermal response shift will be large. In other words, if connecting material  129  is made of a material having a hardness of around 20, there will be almost no correlation between the elongation percentage and the hardness.  
         [0052]     Therefore, if the elongation percentage of connecting material  129  is set to be in the range indicated by the black arrows in  FIG. 4  (the range, in which the output variation is 1.25 (%F.S.×10) or smaller and the elongation percentage is about 400% or higher), connecting material  129  will absorb the stress exerted from housing base  120  to pressure detecting device  110  by the excellent elongation characteristics thereof and pressure detecting apparatus  100  will be provided with excellent thermal response.  
         [0053]     As described above in connection with the embodiments of the invention, connecting material  129  exhibiting excellent elongation characteristics absorbs the stress exerted from housing base  120  so that the stress may not be transmitted to pressure detecting device  110 . Therefore, pressure detecting apparatus  100  exhibits very precise initial detection performances and guarantees very reliable pressure detection performances.  
         [0054]     Although the materials and the shapes of housing base  120  and housing cover  130  and the structures of the constituent elements in pressure detecting apparatus  100  have been described numerically, the descriptions are exemplary and changes and modifications are obvious to those skilled in the art without departing from the true spirit of the invention.  
         [0055]     As described above, since pressure detecting device  110  and housing base  120  are connected and fixed to each other with connecting material  129  exhibiting an elongation percentage of about 400% or higher, pressure detecting apparatus  100  according to the invention facilitates absorbing the exerted stress based on the excellent elongation characteristics thereof and exhibits excellent thermal response. Pressure detecting apparatus  100  that exhibits excellent thermal response facilitates realizing a structure immune to the temperature change caused in the measurement environment and obtaining measurement results with very high reproducibility.  
         [0056]     As described above, the pressure detecting apparatus according to the invention is employable for various kinds of use, in which pressure detection or pressure measurement is conducted.  
         [0057]     The disclosure of Japanese Patent Application No. 2005-130533 filed on Apr. 27, 2005, is incorporated herein.