JP3815282B2 - Pressure sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure sensor that measures pressure by correcting the temperature of an output value of a sensor chip (pressure detection element) that changes due to a temperature change.
[0002]
[Prior art]
Conventionally, this type of pressure sensor is used to measure various fluid pressures such as the hydraulic pressure of a hydraulic circuit used in, for example, construction machines and industrial machines. A prior art pressure sensor is shown in the schematic cross-sectional view of FIG.
[0003]
The pressure sensor 101 has an exterior in which a lower bolt-shaped metal case 130 and a resin connector portion 140 on the upper side of the case are fitted.
[0004]
The case 130 includes a case lower part 131 having a screw part 131a on the outer peripheral surface for screwing into a mounting hole of a hydraulic pressure measuring part of the hydraulic circuit, and a bottomed cylindrical shape connected to the upper side of the case lower part 131 and one outer periphery. For example, a case upper portion 132 having a polygonal shape like a hexagon nut is provided.
[0005]
The case lower part 131 includes a concave part 133 that opens downward at the lower end part, and a through hole 134 that penetrates from the concave part 133 into the upper case upper part 132.
[0006]
A diaphragm 102 is provided at the lower end of the case lower portion 131 so as to face the opening of the recess 133. Further, a cap 103 is attached to the lower end of the case lower part 131 so as to protrude further downward than the diaphragm 102 and protect the diaphragm 102.
[0007]
The cap 103 is provided with a plurality of holes through which the fluid passes so that the fluid directly acts on the diaphragm 102 and the lower surface of the diaphragm 102 serves as a pressure-sensitive portion.
[0008]
The outer peripheral ends of the diaphragm 102 and the cap 103 are fixed to the lower end of the concave 133 by beam welding or TIG welding using an electron beam or the like.
[0009]
Further, in the recess 133 whose opening side is closed by the diaphragm 102, a guide 104 having an introduction hole 104a at the center, and a sensor chip (pressure) provided with a strain gauge directly above the introduction hole 104a of the guide 104 Sensing element) 105 and a ceramic spacer 106 to which the sensor chip 105 is fixed.
[0010]
Note that the inside of the recess 133 whose opening side is closed by the diaphragm 102 is a sealed space, and this space is filled with silicon oil.
[0011]
Within the recess 133, the spacer 106 is fixed to the upper bottom surface of the recess 133. The spacer 106 is provided with a hole at the center of the lower surface, and the sensor chip 105 is disposed in the hole. A conduction pattern is formed around the hole on the lower surface of the spacer 106. The conductive pattern and the sensor chip 105 are connected by a bonding wire.
[0012]
In the recess 133, the guide 104 is fixed to the lower side of the spacer 106 with a gap between the guide 106 and a ring provided on the outer periphery. As described above, since the gap is formed between the spacer 106 and the guide 104, the bonding wire connecting the conductive pattern on the lower surface of the spacer 106 and the sensor chip 105 is also prevented from coming into contact with the guide 104.
[0013]
In the sensor chip 105, the pressure-sensitive portion on the lower surface of the diaphragm 102 receives the pressure of the fluid to be measured, the diaphragm 102 is deformed by this pressure, and silicon oil filled between the diaphragm 102 and the spacer 106 enters the introduction hole 104a. Then, the pressure is transmitted to the sensor chip 105 and the strain gauge of the sensor chip 105 is deformed, so that the output voltage corresponding to the input voltage that changes due to the change in the resistance value of the strain gauge due to the deformation is taken out as the output value. The signal of the output value of the sensor chip 105 is transmitted to the conduction pattern on the lower surface of the spacer 106 through a bonding wire.
[0014]
A conductive pin 107 is inserted into the through hole 134 of the case lower part 131. The periphery of the pin 107 of the through-hole 134 is sealed with glass 108 to ensure insulation and prevent the pin 107 from conducting to the case lower part 131 and the silicon oil filled in the recess 133 penetrates. Leakage into the hole 134 is prevented.
[0015]
Further, the lower end of the pin 107 protrudes from the lower surface of the spacer 106, and the conduction pattern between the lower end of the pin 107 and the lower surface of the spacer 106 is conducted. On the other hand, the upper end of the pin 107 protrudes into the case upper part 132. Therefore, the signal of the output value of the sensor chip 105 is further transmitted to the pin 107 from the conduction pattern on the lower surface of the spacer 106.
[0016]
The case upper part 132 accommodates the printed circuit board 114 and the HIC (hybrid IC) 110 inside. The bottom surface inside the case upper portion 132 is covered with a resin insulator 109 which is an insulator. The insulator 109 positions and fixes the pin 107 protruding from the through hole 134 of the case lower part 131. The HIC 110 is supported and fixed by a pin 107 positioned and fixed by the insulator 109 and a convex portion protruding from the insulator 109.
[0017]
The HIC 110 is provided above the insulator 109. The HIC 110 is provided with an ASIC (custom IC) 111 that performs amplification and correction of the signal of the output value of the sensor chip 105 by digital trimming on the lower surface side of the HIC 110.
[0018]
The ASIC 111 amplifies and corrects the signal of the output value of the sensor chip 105 by digital trimming. Since the output value of the sensor chip 105 changes depending on the temperature condition, the pressure sensor 101 performs temperature correction on the signal of the output value of the sensor chip 105 by the ASIC 111 so that a signal independent of the temperature condition can be output. Yes. For this reason, the ASIC 111 has a built-in thermosensitive mechanism for detecting the temperature, and the temperature correction is performed by correcting the output value of the sensor chip 105 using the temperature detected by the thermosensitive mechanism.
[0019]
Further, the upper end of the pin 107 protruding into the case upper portion 132 reaches the HIC 110, and the circuit of the HIC 110 and the upper end of the pin 107 are soldered. Further, the HIC 110 has a plurality of comb leads 112 extending in the vicinity of the center, and the comb leads 112 are connected to the circuit of the HIC 110. That is, the signal of the output value of the sensor chip 105 transmitted to the pin 107 is amplified and corrected by the ASIC 111 provided in the HIC 110, and then the amplified and corrected signal is transmitted to the comb lead 112. .
[0020]
The case upper portion 132 is filled with a potting agent 113 such as silicon gel from the insulator 109 to the upper side of the HIC 110 to protect each member. This potting agent 113 enhances the thermal coupling between the ASIC 111 provided in the HIC 110 and the case lower part 131 by intervening, and the temperature difference between the thermal mechanism built in the ASIC 111 and the sensor chip 105 in the case lower part 131 is increased. I try to reduce it. Furthermore, the thermal coupling is also improved by disposing the ASIC 111 on the lower surface side of the HIC 110 and bringing the ASIC 111 closer to the lower case 131.
[0021]
Above the HIC 110, a ceramic printed board 114 having a conductive pattern printed on its surface is provided. The printed circuit board 114 is provided with a transistor 115 for controlling the amount of power supplied to the sensor chip 105, a pin header 116 for connecting a flexible circuit or a lead wire 117, and the like. The transistor 115 is arranged on the outer peripheral side and the upper surface side of the printed circuit board 114 farthest from the vicinity of the center where the upper end of the comb lead 112 is soldered on the printed circuit board 114.
[0022]
On the printed circuit board 114, the transistor 115, the pin header 116, and the like are connected to a conductive pattern. The printed circuit board 114 is supported and fixed to the upper end portion of the comb lead 112 in the vicinity of the center, and the conductive pattern on the printed circuit board 114 and the upper end of the comb lead 112 are soldered.
[0023]
Since the printed circuit board 114 is made of ceramic having high thermal conductivity, when a heat generating element such as the transistor 115 and the conduction pattern provided on the printed circuit board 114 generates heat when energized, the heat is conducted to the entire printed circuit board 114, and the printed circuit board 114 is printed. The heat is dissipated by diffusing from the substrate 114 into the air inside the case upper portion 132.
[0024]
The signal amplified and corrected by the ASIC 111 is transmitted to the comb lead 112 and then transmitted from the pin header 116 to the flexible circuit or the lead wire 117 via the printed circuit board 114.
[0025]
On the upper side of the printed circuit board 114, a lid-shaped metal plate 118 is provided. The plate 118 has its outer peripheral end locked to the inner periphery of the upper end of the case upper portion 132. The plate 118 is provided with a feedthrough capacitor 119 near the center, and the feedthrough capacitor 119 is connected to the connector pin 143 of the connector 142 by soldering. A flexible circuit or lead wire 117 is also soldered to the connector pin 143 and connected. A reinforcing substrate 120 for improving durability is interposed in a connection portion between the flexible circuit or the lead wire 117 and the connector pin 143.
[0026]
On the upper side of the plate 118, a lid-like connector part 140 is attached to the case upper part 132. The lower end of the connector part 140 supports the plate 118, and the annular convex part on the outer periphery of the lower end of the connector part 140 is caulked and fixed to the upper end of the case upper part 132. An O-ring 121 that seals the inside of the case upper portion 132 is attached to a portion surrounded by the lower end of the connector portion 140, the annular convex portion, the outer edge of the plate 118, and the inner periphery of the case upper portion 132.
[0027]
Further, the connector part 140 is provided with a substantially rectangular parallelepiped connector 142 at the top, and a connector pin 143 provided inside the connector 142 reaches the inside of the case upper part 132 and is soldered to the feedthrough capacitor 119.
[0028]
Then, the signal amplified and corrected by the ASIC 111 is transmitted from the flexible circuit or lead wire 117 to the connector pin 143 through the feedthrough capacitor 119 and taken out from the pressure sensor 101.
[0029]
[Problems to be solved by the invention]
In the case of the conventional pressure sensor 101 as described above, the sensor chip 105 changes its output value depending on temperature conditions even at the same pressure. For this reason, in the pressure sensor 101 of the prior art, the ASIC 111 performs temperature correction on the output value signal of the sensor chip 105 and outputs a signal that does not depend on the temperature condition.
[0030]
The ASIC 111 can easily perform amplification and temperature correction by digital trimming. The ASIC 111 has a built-in thermal mechanism, detects the temperature with the thermal mechanism, and performs temperature correction based on the temperature detected by the thermal mechanism. For this reason, if the temperature of the heat sensitive mechanism of the ASIC 111 is significantly different from the temperature of the sensor chip 105, the temperature correction is performed for a temperature different from the temperature to which the temperature correction is to be performed, resulting in a large error.
[0031]
In order to prevent this error from increasing, conventionally, as shown in FIG. 4, an ASIC 111 having a built-in thermal mechanism is installed in the HIC 110, and a heating element such as a transistor 115 and a conduction pattern is provided on the printed circuit board 114. The heat sensitive mechanism and the heating element are separately installed on two different substrates to prevent the propagation of heat to the AISC 111 as much as possible.
[0032]
However, the heat generation of the transistor 115 which is a power supply circuit portion is mainly as large as about 100 mW or more, and heat is propagated to the HIC 110 through the comb lead 112 even if the transistor 115 is installed on the printed circuit board 114. Heat also propagates in the air.
[0033]
As a result, the detected temperature of the thermal mechanism built into the ASIC 111 is also higher than the actual temperature of the sensor chip 105, and the temperature difference becomes large. Therefore, the signal subjected to temperature correction using the detected temperature of the thermal mechanism is There is a problem that a large error occurs with respect to the actual pressure, and the output accuracy is lowered.
[0034]
Further, when the heat generating element generates heat by energization, the heat of the heat generating element conducts heat with the passage of time, so that the temperature of the heat sensitive mechanism rises higher than the actual temperature of the sensor chip 105 with the passage of time. For this reason, the error of the signal subjected to temperature correction increases with respect to the actual pressure over time. Therefore, there is a problem that the output accuracy deteriorates and becomes unstable as time elapses after the power is turned on.
[0035]
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a pressure sensor that performs temperature correction with less error to improve output accuracy.
[0036]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides:
A pressure sensing element;
A thermosensitive mechanism for temperature detection to be used for temperature correction of the output value of the pressure detection element;
A heating element that generates heat when energized during operation;
With
A pressure sensor in which the thermal mechanism and the heating element are separately installed on two different substrates;
Each of the two substrates is separately disposed in two different chambers, and the two substrates are connected by a flexible connecting member.
[0037]
Therefore, the heat of the heating element generated by energization is generated in a separate chamber from the chamber in which the substrate on which the thermal mechanism is installed is disposed, and the flexible connection member radiates heat, so the thermal mechanism is passed through the flexible connection member. Is not propagated to the substrate on which the heat sensor is placed, so that the heat of the heating element can be prevented from being conducted to the thermal mechanism, and the temperature detected by the thermal mechanism is not higher than the temperature of the actual pressure sensor and the temperature difference does not increase. Therefore, the error of the signal subjected to temperature correction using the detected temperature of the thermal mechanism is reduced with respect to the actual pressure, and the output accuracy can be improved.
[0038]
Further, even if time elapses, the heat of the heat generating element does not conduct heat to the heat sensitive mechanism, so that the temperature of the heat sensitive mechanism does not rise with time. For this reason, the error of the signal subjected to temperature correction does not increase with respect to the actual pressure over time. Therefore, stable output accuracy can be maintained even if time elapses after the power is turned on.
[0039]
The flexible connecting member is preferably thin and long.
[0040]
Thereby, since the heat transmitted through the flexible connecting member is radiated on the way, it is possible to prevent the heat from being transmitted to the substrate on which the heat-sensitive mechanism is installed.
[0041]
The two chambers are preferably separated by a plate.
[0042]
Thereby, two chambers can be formed using an existing plate without increasing the number of parts.
[0043]
The substrate on which the heating element is installed is provided with a probe pad for digital trimming,
It is preferable to perform digital trimming by connecting a probe pin to the probe pad after completion of assembly of all processes.
[0044]
As a result, output fluctuation may have occurred when all process assembly is completed after performing digital trimming, but digital trimming is performed after completion of all process assembly, so output adjustment does not occur and high-precision adjustment can be performed. The output accuracy can be improved. Further, digital trimming can be easily performed again.
[0045]
It is preferable that a probing hole for connecting a probe pin to the probe pad is formed inside a connector provided with input / output terminals.
[0046]
Thereby, since the sealing performance inside the connector is good, the final sealing of the probing hole can be easily performed, and the operation can be simplified.
[0047]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0048]
(First embodiment)
The first embodiment will be described below with reference to FIG. FIG. 1 is a sectional view showing a pressure sensor according to the first embodiment.
[0049]
The pressure sensor 1 is used for measuring various fluid pressures such as the hydraulic pressure of a hydraulic circuit used for construction machines, industrial machines, etc., as in the prior art.
[0050]
The pressure sensor 1 has an exterior in which a lower bolt-shaped metal case 30 and a resin connector portion 40 on the upper side of the case are fitted.
[0051]
The case 30 includes a case lower portion 31 having a screw portion 31a on the outer peripheral surface for screwing into a mounting hole of a hydraulic pressure measuring portion of the hydraulic circuit, and a bottomed cylindrical shape connected to the upper side of the case lower portion 31 and one outer periphery A case upper portion 32 having a polygonal shape such as a hexagonal nut is provided.
[0052]
The case lower portion 31 includes a recess 33 that opens downward at the lower end portion, and a through hole 34 that penetrates from the recess 33 to the inside of the upper case upper portion 32.
[0053]
The diaphragm 2 is provided at the lower end of the case lower portion 31 so as to face the opening of the recess 33. Further, a cap 3 that protects the diaphragm 2 is attached to the lower end of the case lower part 31 so as to protrude further downward than the diaphragm 2.
[0054]
The cap 3 is provided with a plurality of holes through which the fluid passes so that the fluid directly acts on the diaphragm 2 and the lower surface of the diaphragm 2 serves as a pressure-sensitive portion.
[0055]
The outer peripheral end portions of the diaphragm 2 and the cap 3 are fixed to the lower end of the concave portion 33 by beam welding or TIG welding using an electron beam or the like all around.
[0056]
Further, in the concave portion 33 whose opening side is closed by the diaphragm 2, a guide 4 having an introduction hole 4a in the center, and a sensor chip (pressure) provided with a strain gauge directly above the introduction hole 4a of the guide 4 Detection element) 5 and a ceramic spacer 6 to which the sensor chip 5 is fixed.
[0057]
In addition, the inside of the recessed part 33 with which the opening side was block | closed with this diaphragm 2 becomes a sealed space, and this space is filled with silicon oil.
[0058]
Within the recess 33, the spacer 6 is fixed to the upper bottom surface of the recess 33. The spacer 6 is provided with a hole at the center of the lower surface, and the sensor chip 5 is disposed in the hole. A conduction pattern is formed around the hole on the lower surface of the spacer 6. The conductive pattern and the sensor chip 5 are connected by a bonding wire.
[0059]
In the recess 33, the guide 4 is fixed to the lower side of the spacer 6 with a gap between the guide 6 and a ring provided on the outer periphery. As described above, since the gap is formed between the spacer 6 and the guide 4, the bonding wire connecting the conductive pattern on the lower surface of the spacer 6 and the sensor chip 5 is also prevented from coming into contact with the guide 4.
[0060]
In the sensor chip 5, the pressure-sensitive portion on the lower surface of the diaphragm 2 receives the pressure of the fluid to be measured, the diaphragm 2 is deformed by this pressure, and silicon oil filled between the diaphragm 2 and the spacer 6 enters the introduction hole 4 a. Then, pressure is transmitted to the sensor chip 5 and the strain gauge of the sensor chip 5 is deformed, so that an output voltage corresponding to an input voltage that changes due to a change in the resistance value of the strain gauge due to the deformation is taken out as an output value. The signal of the output value of the sensor chip 5 is transmitted to the conduction pattern on the lower surface of the spacer 6 through the bonding wire.
[0061]
In the sensor chip 5 according to the present embodiment, the strain gauge resistance is changed by the deformation of the strain gauge, and the output voltage is changed with respect to the input voltage. Since it varies depending on conditions, the output value may vary depending on temperature conditions even at the same pressure.
[0062]
A conductive pin 7 is inserted through the through hole 34 of the case lower part 31. The periphery of the pin 7 of the through hole 34 is sealed with glass 8 to ensure insulation and prevent the pin 7 from conducting to the case lower part 31 and the silicon oil filled in the recess 33 penetrates. Leakage into the hole 34 is prevented.
[0063]
Further, the lower end of the pin 7 protrudes from the lower surface of the spacer 6, and the conduction pattern between the lower end of the pin 7 and the lower surface of the spacer 6 is conducted. On the other hand, the upper end of the pin 7 protrudes into the case upper part 32. Therefore, the signal of the output value of the sensor chip 5 is further transmitted to the pin 7 from the conduction pattern on the lower surface of the spacer 6.
[0064]
The case upper part 32 accommodates the HIC (hybrid IC) 10 inside. The bottom surface inside the case upper portion 32 is covered with a resin insulator 9 which is an insulator. The insulator 9 positions and fixes the pin 7 protruding from the through hole 34 of the case lower part 31. The HIC 10 is supported and fixed by the pin 7 positioned and fixed by the insulator 9 and the convex portion protruding from the insulator 9.
[0065]
The HIC 10 is provided on the upper side of the insulator 9. The HIC 10 is provided with an ASIC (custom IC) 11 on the lower surface side of the HIC 10 that amplifies and corrects the signal of the output value of the sensor chip 5 by digital trimming.
[0066]
The ASIC 11 performs amplification and correction of the signal of the output value of the sensor chip 5 by digital trimming. In particular, in the pressure sensor 1 according to the present embodiment, since the output value of the sensor chip 5 changes depending on the temperature condition, the ASIC 11 performs temperature correction on the signal of the output value of the sensor chip 5, and the pressure sensor 1 depends on the temperature condition. So that no signal can be output. For this reason, the ASIC 11 has a built-in heat sensing mechanism for temperature detection, and the temperature correction is performed by correcting the output value of the sensor chip 5 using the temperature detected by the heat sensing mechanism.
[0067]
Further, the upper end of the pin 7 protruding into the case upper portion 32 reaches the HIC 10, and the circuit of the HIC 10 and the upper end of the pin 7 are soldered.
[0068]
The HIC 10 is provided with a pin header 12 on the upper surface for performing digital trimming of the ASIC 11.
[0069]
Further, a flexible circuit or lead wire 13 extending upward is soldered to the HIC 10.
[0070]
That is, the signal of the output value of the sensor chip 5 transmitted to the pin 7 is amplified and corrected by the ASIC 11 provided in the HIC 10 and then the amplified and corrected signal is sent to the flexible circuit or the lead wire 13. Communicated.
[0071]
The case upper portion 32 is filled with a potting agent 14 such as silicon gel from the insulator 9 to the upper side of the HIC 10 to protect each member. The potting agent 14 increases the thermal coupling between the ASIC 11 provided in the HIC 10 and the case lower portion 31 by intervening, and the temperature difference between the heat sensitive mechanism built in the ASIC 11 and the sensor chip 5 in the case lower portion 31 is increased. I try to reduce it. Furthermore, the thermal coupling is also improved by disposing the ASIC 11 on the lower surface side of the HIC 10 and bringing the ASIC 11 closer to the case lower portion 31.
[0072]
A lid-shaped metal plate 15 is provided on the upper side of the HIC 10. The plate 15 has its outer peripheral end locked to the inner periphery of the upper end of the case upper portion 32. The plate 15 is provided with a feedthrough capacitor 16 in the vicinity of the center, and the feedthrough capacitor 16 is connected to the connector pin 43 of the connector 42 by soldering. Further, the flexible circuit or the lead wire 13 penetrates the through hole of the plate 15 and is connected to a printed circuit board 17 having a transistor 18 provided above the plate 15 and a heating element such as a conduction pattern.
[0073]
On the upper side of the plate 15, a lid-like connector part 40 is attached to the case upper part 32. The lower end of the connector part 40 supports the plate 15, and the annular convex part on the outer periphery of the lower end of the connector part 40 is fixed to the upper end of the case upper part 32 by caulking. An O-ring 19 that seals the inside of the case upper portion 32 is attached to a portion surrounded by the lower end of the connector portion 40, the annular convex portion, the outer edge of the plate 15, and the inner periphery of the case upper portion 32.
[0074]
An internal space formed by mounting the case upper portion 32 and the connector portion 40 is formed in two upper and lower lower chambers 20 and 21 separated by the plate 15. For this reason, it can be said that the HIC 10 is installed in the lower chamber 20.
[0075]
In the upper chamber 21, a ceramic printed board 17 having a conductive pattern printed on the surface is fixed to the lower surface of the connector portion 40.
[0076]
The printed circuit board 17 has a conductive pattern on the printed circuit board 17 and a flexible circuit or lead wire 13 soldered thereto. The printed circuit board 17 is provided with a transistor 18 or the like that controls the amount of power supplied to the sensor chip 5. The transistor 18 is arranged on the outer peripheral side of the printed circuit board 17 farthest from the position where the flexible circuit or the lead wire 13 is soldered on the printed circuit board 17. The transistor 18 and the like are connected to a conduction pattern on the printed circuit board 17.
[0077]
Since the printed circuit board 17 is made of ceramic having a high thermal conductivity, when a heating element such as the transistor 18 and the conduction pattern provided on the printed circuit board 17 generates heat when energized, the heat is transferred to the entire printed circuit board 17 and is printed. The heat is diffused by diffusing from the substrate 17 into the air inside the upper chamber 21. However, since the radiated heat separates the upper chamber 21 and the lower chamber 20 by the plate 15, heat conduction to the lower chamber 20 by air propagation is greatly reduced.
[0078]
Further, even if the heat of the transistor 18 having a high calorific value is thermally conducted to the flexible circuit or the lead wire 13 through the printed circuit board 17, the flexible circuit or the lead wire 13 dissipates the heat on the way, so that the heat is conducted to the HIC 10. It is prevented.
[0079]
Here, if the flexible circuit or the lead wire 13 is thin and long, the heat dissipation efficiency is further increased, and heat conduction to the HIC 10 can be more preferably prevented.
[0080]
The signal amplified and corrected by the ASIC 11 is transmitted to the flexible circuit or the lead wire 13 and then transmitted to the printed circuit board 17.
[0081]
Further, the connector portion 40 having the printed circuit board 17 fixed to the lower surface is provided with a substantially rectangular parallelepiped connector 42 at the top, and the connector pin 43 provided in the connector 42 reaches the inside of the case upper portion 32 to reach the printed circuit board 17. And the feedthrough capacitor 16.
[0082]
Then, the signal amplified and corrected by the ASIC 11 is transmitted from the printed circuit board 17 to the connector pin 43 and taken out from the pressure sensor 1.
[0083]
In the pressure sensor 1 of the present embodiment having the above-described configuration, the ASIC 11 incorporating the thermal mechanism is installed in the HIC 10, and the heating elements such as the transistor 18 and the conduction pattern are installed in the printed circuit board 17. The heating elements are separately installed on different substrates, and each of these two substrates is separately arranged in two different lower chambers 20 and upper chambers 21, and the two substrates are connected by a flexible circuit or lead wire 13. As a result, the heat of the heating element generated by energization is generated in the upper chamber 21 separate from the lower chamber 20 in which the substrate on which the thermal mechanism is installed is disposed, and the flexible circuit or the lead wire 13 dissipates heat. Therefore, it does not propagate through the flexible circuit or the lead wire 13 to the substrate on which the heat sensitive mechanism is arranged, so that the heat of the heating element is transferred to the heat sensitive mechanism. Since the temperature detected by the thermal mechanism does not become higher than the actual temperature of the sensor chip 5 and the temperature difference does not increase, the signal subjected to temperature correction using the detected temperature of the thermal mechanism is the actual pressure. As a result, the error can be reduced and the output accuracy can be improved.
[0084]
Further, even if time elapses, the heat of the heat generating element does not conduct heat to the heat sensitive mechanism, so that the temperature of the heat sensitive mechanism does not rise with time. For this reason, the error of the signal subjected to temperature correction does not increase with respect to the actual pressure over time. Therefore, stable output accuracy can be maintained even if time elapses after the power is turned on.
[0085]
Since the flexible circuit or the lead wire 13 is thin and long, the heat transmitted through the flexible circuit or the lead wire 13 is dissipated in the middle, so that it is possible to prevent the heat from being propagated to the substrate on which the thermal mechanism is installed.
[0086]
Since the two lower chambers 20 and the upper chamber 21 are separated by the plate 15, two chambers can be formed without increasing the number of components using the plate 15 that has been conventionally used as components, Costs can be prevented from increasing.
[0087]
Since the printed circuit board 17 is made of ceramic, it is easy to conduct heat on the printed circuit board 17, and the heat of the heating element generated by energization is conducted to the entire printed circuit board 17 and diffused from the printed circuit board 17 into the air. However, other members having good thermal conductivity may be used.
[0088]
(Second Embodiment)
In the first embodiment, a trimming counterpart connector is inserted into the pin header 12 on the HIC 10 and digital trimming is performed to adjust the output of the ASIC 11. Therefore, digital trimming is performed after soldering of the HIC 10 or the like, soldering of the flexible circuit or the lead wire 13 to the HIC 10, and various soldering of the connector portion 40 (after attachment). After that, the pressure sensor 1 is completed through processes such as filling of the potting agent 14, potting cure, and caulking of the connector part 40 to the case upper part 32.
[0089]
Therefore, in the first embodiment, at the time of digital trimming, the output value can be made almost as intended by adjusting the output, but after subsequent steps (potting agent 14 filling, potting cure, caulking, etc.) The output fluctuates, and when the assembly of the pressure sensor 1 is completed, the value may be different from that at the time of digital trimming.
[0090]
In addition, when digital trimming is performed by inserting a mating connector on the pin header 12 on the HIC 10, the trimming is performed one by one because the pin header 12 is in a recessed position or the position is not determined. May have to be performed while the operator confirms, and workability may be poor.
[0091]
Furthermore, since the mating connector inserted into the pin header 12 also has a lifetime, regular maintenance is required.
[0092]
Even if the output is shifted and it is desired to perform trimming again, it is necessary to disassemble the connector portion 40 after crimping, and it is practically difficult to perform trimming again.
[0093]
In addition, the pin header 12 for trimming has a high unit price and takes up space (at least 8 poles are required), so that the mounting pattern of the HIC 10 and the number of mountable parts are limited, which becomes a bottleneck for miniaturization. ing.
[0094]
Therefore, in the present embodiment, the pin header 12 is removed from the configuration of the first embodiment, the probe pad 22 is provided on the upper surface of the printed circuit board 17, and the probe pin 24 is connected to the probe pad 22 through the probing hole 23. Thus, digital trimming is performed after assembly of all processes.
[0095]
Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals, and the description thereof is omitted.
[0096]
FIG. 2 shows a second embodiment. As shown in FIG. 2, probe pads 22 are provided on the lower surface of the connector portion 40 and the upper surface of the printed circuit board 17 fixed thereto. The probe pad 22 can be digitally trimmed by being connected to the probe pin 24.
[0097]
Here, the ASIC 11 currently used needs to electrically connect a total of seven terminals including three input / output terminals (Vin, Vout (for voltage type), COM) and four communication terminals at the time of digital trimming. There is. Therefore, in the first embodiment, the 8-pole pin header 12 is used. However, in this embodiment, since the three input / output terminals can use the connector pin 43, the probe pad 22 has four probe pads 22 for communication. I have prepared it.
[0098]
Further, in the connector portion 40, a probing hole 23 is formed on the outside of the connector 42 so as to penetrate inside and outside so that the probe pin 24 can be brought into contact with the probe pad 22. The probing hole 23 is closed with a hard potting agent after the digital trimming is completed, and at the same time, the airtightness inside the pressure sensor 1 is secured.
[0099]
In the present embodiment, since digital trimming is performed using the probe pad 22 of the printed circuit board 17, the HIC 10 is not provided with the adjustment pin header 12.
[0100]
For this reason, in this embodiment, soldering of the HIC 10, soldering of the flexible circuit or lead wire 13 to the HIC 10, filling of the potting agent 14, potting cure, various soldering of the connector part 40, and the case upper part 32 of the connector part 40 After the assembly of the pressure sensor 1 through the caulking process, the probe pin 24 is connected to the probe pad 22 through the probing hole 23, and digital trimming is performed.
[0101]
Therefore, output variation may occur when all process assembly is completed after digital trimming as in the first embodiment. However, output variation may occur because digital trimming is performed after all process assembly is completed. Therefore, highly accurate adjustment can be performed, and the accuracy can be improved. In addition, when the temperature characteristics are measured and NG or the like is performed, digital trimming can be easily performed again.
[0102]
Further, since the digital trimming is performed by connecting the probe pin 24 to the exposed probe pad 22, the operator can easily connect the probe pin 24, and the workability is good.
[0103]
Furthermore, the probe pin 24 to be connected has a long life, and regular maintenance is not required, and free maintenance can be achieved.
[0104]
Furthermore, since the HIC 10 has a high unit price and does not have the pin header 12 that takes up space (at least 8 poles are required), the cost can be reduced and the size can be reduced without limiting the mounting pattern and the number of mountable components of the HIC 10. .
[0105]
On the other hand, in terms of work process, probing is easy to automate, and there is a merit that it is easy to deal with a longitudinal flow line, and the process can be simplified.
[0106]
(Third embodiment)
In the second embodiment, in addition to the connection of the three input / output terminals, the four probe pads 22 for communication must be connected, and the counterpart connector for trimming may be complicated and large in some cases. There are things to do.
[0107]
Therefore, in the present embodiment, the configuration of the second embodiment is changed, and the probe pin 24 is connected to the probe pad 22 through the probing hole 23 formed in the connector 42.
[0108]
Since other configurations and operations are the same as those of the second embodiment, the same components are denoted by the same reference numerals, and description thereof is omitted.
[0109]
FIG. 3 shows a third embodiment. As shown in FIG. 3, a probing hole 23 is formed in the connector 42 of the connector portion 40 next to the connector pins 43 which are three input / output terminals. A probe pad 22 is provided on the upper surface of the printed circuit board 17 below the probing hole 23.
[0110]
Therefore, the digital trimming can be performed by attaching the integrated trimming counterpart connector for connecting the four probe pads 22 for communication simultaneously with the connection of the three input / output terminals to the connector 42. When the side connector is attached, the operation of completing the trimming attachment operation can be simplified.
[0111]
In addition, since the probing hole 23 is located inside the connector 42, if the waterproof connector is used, the inside of the connector 42 has good sealing properties such as no ingress of water or the like from the outside. The hole 23 can be finally sealed (filling with a potting agent) (the sealing performance required for potting can be low or ultimately potting is not required), and the work can be performed. Simplification can be achieved.
[0112]
【The invention's effect】
As described above, the present invention is a pressure sensor in which the thermal mechanism and the heating element are separately installed on two different substrates, and each of the two substrates is disposed in two different chambers. Since the two substrates are connected to each other by the flexible connecting member, the heat of the heating element generated by energization is generated in a separate chamber from the chamber in which the substrate on which the thermal mechanism is installed is arranged, and is flexible. Since the connection member dissipates heat and does not propagate through the flexible connection member to the substrate on which the heat sensitive mechanism is arranged, heat from the heating element can be prevented from being conducted to the heat sensitive mechanism, and the temperature detected by the heat sensitive mechanism is the actual pressure. Since the temperature does not become higher than the temperature of the sensing element and the temperature difference does not increase, the signal corrected for temperature using the sensing temperature of the thermal mechanism reduces errors with respect to the actual pressure and improves output accuracy. Can do.
[0113]
Further, even if time elapses, the heat of the heat generating element does not conduct heat to the heat sensitive mechanism, so that the temperature of the heat sensitive mechanism does not rise with time. For this reason, the error of the signal subjected to temperature correction does not increase with respect to the actual pressure over time. Therefore, stable output accuracy can be maintained even if time elapses after the power is turned on.
[0114]
Since the flexible connecting member is thin and long, heat transmitted through the flexible connecting member is dissipated on the way, so that heat can be prevented from propagating to the substrate on which the heat sensitive mechanism is installed.
[0115]
Since the two chambers are separated by the plate, the two chambers can be formed using the existing plate without increasing the number of parts.
[0116]
When the substrate on which the heating element is installed is equipped with a probe pad for digital trimming, and assembly of all processes is completed after digital trimming is performed by connecting the probe pin to the probe pad after completion of all process assembly. Although output fluctuation sometimes occurred, since digital trimming is performed after assembly of all processes, output fluctuation does not occur and high-precision adjustment can be performed, and output accuracy can be improved. Further, digital trimming can be easily performed again.
[0117]
Probing holes for connecting the probe pins to the probe pads are formed inside the connector with the input / output terminals, so that the sealing performance inside the connector is good. Sealing can be performed easily and the operation can be simplified.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a pressure sensor according to a first embodiment.
FIG. 2 is a cross-sectional view showing a pressure sensor according to a second embodiment.
FIG. 3 is a cross-sectional view showing a pressure sensor according to a third embodiment.
FIG. 4 is a cross-sectional view showing a conventional pressure sensor.
[Explanation of symbols]
1 Pressure sensor
2 Diaphragm
3 cap
4 Guide
4a Introduction hole
5 Sensor chip
6 Spacer
7 pin
8 Glass
9 Insulator
10 HIC (Hybrid IC)
11 ASIC (Custom IC)
12 pin header
13 Flexible circuit or lead wire
14 Potting agents
15 plates
16 Feedthrough capacitor
17 Printed circuit board
18 transistors
19 O-ring
20 lower chamber
21 Upper room
22 Probe pad
23 Probing hole
24 Probe pin
30 cases
31 Lower case
31a Screw part
32 Case top
33 recess
34 Through hole
40 Connector section
42 Connector
43 Connector pin

Claims (5)

A pressure sensing element;
A thermosensitive mechanism for temperature detection to be used for temperature correction of the output value of the pressure detection element;
A heating element that generates heat when energized during operation;
With
A pressure sensor in which the thermal mechanism and the heating element are separately installed on two different substrates;
Each of the two substrates is separately disposed in two different chambers, and the two substrates are connected by a flexible connecting member. The pressure sensor according to claim 1, wherein the flexible connecting member is thin and long. The pressure sensor according to claim 1 or 2, wherein the two chambers are separated by a plate. The substrate on which the heating element is installed is provided with a probe pad for digital trimming,
4. The pressure sensor according to claim 1, wherein digital trimming is performed by connecting a probe pin to the probe pad after completion of all process assembly. 5. 5. The pressure sensor according to claim 4, wherein a probing hole for connecting a probe pin to the probe pad is formed inside a connector provided with an input / output terminal.

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